JP4315045B2 - Belt for image forming apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an intermediate transfer belt used for an electrophotographic copying machine, a laser beam printer, a facsimile machine, and the like, comprising an endless endless belt excellent in physical properties such as molding dimensional stability and bending resistance. The present invention relates to an image forming apparatus belt such as a transfer belt, a photoreceptor belt, and a fixing belt, and an image forming apparatus including the image forming apparatus belt.

  As an image forming apparatus such as an OA device, an electrophotographic system using a photoreceptor and toner is put on the market. These devices include conductive belts, intermediate transfer belts, transfer transfer belts, transfer separation belts, charging tubes, developing sleeves, fixing belts, toner transfer belts, etc., regardless of the presence or absence of seams, conductive, semiconductive, insulating Endless belts controlled to various electrical resistances are used.

  For example, the intermediate transfer device 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 electric resistance in the thickness direction (hereinafter referred to as “volume electric resistance”) for each machine model, and is adjusted to be conductive, semiconductive, or insulative.

  The transport transfer device is configured to hold the paper once on the transport transfer body, transfer the toner from the photosensitive member onto the paper held on the transport transfer body, and further remove the paper from the transport transfer body by discharging. Has been. 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. 2 is a side view of a conventional 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, it is 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 to differentiate it from the inkjet system with a high-speed printing technology, and an image forming apparatus that performs high-speed printing with a tandem conveyance transfer and intermediate transfer system in which four photoconductors are arranged. It 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 for differentiation from inkjet printers.

  As a result, development of polymerized toners has progressed, and toners with a small particle size of 4 to 6 μm and small variations in particle size have been commercialized, and there is a demand for improvements in surface properties, chemical properties, and electrical properties of transfer belts. Is also increasing.

  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 to paper with electrostatic force (secondary transfer), 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 the surface physical characteristics and surface chemical characteristics need to be improved. There is.

From the above, the following conditions (1) to (8) are required for image forming apparatus belts such as transfer belts in recent years.
(1) Predetermined surface electrical resistivity and volume electrical resistivity in the semiconductor region, and resistance variation is small
(2) Toner releasability
(3) Thin and uniform thickness
(4) Strong mechanical strength (hard to stretch and hard to break)
(5) Less variation in resistance, dimensions, and mechanical strength due to the environment (temperature and humidity)
(6) Low cost
(7) Seamless and perfect circle (with little difference in circumference in the belt width direction) belt
(8) Capable of high-quality printing on various paper types

  Up to now, endless belts have been molded by blending a thermosetting or thermoplastic resin with a conductive filler such as carbon black or conductive metal filler, or with an ion conductive material. It is mainly used, for example, carbon black such as acetylene black, furnace black, channel black and insulating properties in resin compositions such as polyamide, polyimide, polyvinylidene fluoride, ethylene tetrafluoroethylene copolymer, polycarbonate, polyester, etc. By adding an ionic conductive substance to the polymer of which the electrical resistivity is adjusted, and molding this to a thickness of several tens to several hundreds of micrometers, a predetermined electrical resistivity (surface electrical resistivity) is obtained. , Volumetric electrical resistivity), a resin belt, an intermediate transfer belt, paper transport and toner It is known to use a transfer belt that also serves as a transfer (Japanese Patent Laid-Open Nos. 63-111267, 5-170946, 6-228335, 3-89357, etc.) ).

  Further, as a material other than the resin material, an endless belt made of a flexible material such as rubber or thermoplastic elastomer has been proposed (Japanese Patent Laid-Open Nos. 9-54506, 8-99374, and 10-6411). No., JP-A 2000-62993, JP-A 2001-13802).

  In addition, the following methods are considered as a manufacturing method of an endless belt.

(a) Rotational molding method (or sometimes expressed as centrifugal molding method)
Put the resin in which the solution is dissolved on the inner peripheral surface of the cylindrical mold, apply temperature while rotating the mold, volatilize the solvent by half or more, and then remove the seamless tube from the mold. And a step of attaching a seamless tube to the outside of the cylindrical mold and applying a temperature to cause a thermosetting reaction (JP-A-60-170862). This method is mainly used for manufacturing a polyimide transfer belt.

(b) Extrusion molding method This is a method in which a resin compounded with a conductive filler is melt-extruded in a ring shape. This method is mainly used in a method for producing an ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride, polycarbonate-based, polyester-based, or polyimide-based transfer belt.

(c) Dipping method In this method, a resin solution is applied to the outer surface of a cylindrical or columnar mold by dipping or the like to form a fixed thickness, and after heating to form a film, the tubular film formed from the mold is pulled out. This method is mainly used for producing a transfer film made of polyvinylidene fluoride.

(d) Rubber Extrusion Method A method has been reported in which polyurethane rubber is extruded and vulcanized into a cylindrical shape, and then the surface is polished and the surface of the outer layer is coated with a fluororesin or the like (Electrophotographic Society Journal 33 (1) 43 ( 1994)).

  Among resin-based endless belts, those based on thermoplastic resin are easy to continuously mold, and resin-made endless belts made by extrusion have been widely used because they can aim to reduce costs. (Kaihei 3-89357). However, an endless belt in which a conductive agent is simply added to a resin material is inferior in bending resistance. For example, when used in electrophotography as an intermediate transfer belt, there is a problem that cracks are likely to occur during use.

  In order to solve this problem, an alloyed endless belt made of an alloy formed by blending polycarbonate and a polyalkylene terephthalate such as polybutylene terephthalate (PBT) has been proposed and commercialized, and has achieved a certain result (Japanese Patent Laid-Open No. 4-313757 and JP-A-6-149083). However, there remains a problem that cracks are likely to occur, and it is necessary to attach a reinforcing tape or the like for the purpose of reinforcing the belt end, resulting in an increase in cost.

  Also, alloy belts combining various engineering plastics such as polyarylate / polyester, polyalkylene terephthalate / polyamide, polycarbonate / polyamide, polysulfone, polyethersulfone and polyester, polyphenylene sulfide have been proposed as resin alloy belts. Yes.

  However, these resin-based alloy materials have a problem that not only the bending resistance is originally poor but also the bending resistance is further deteriorated when a conductive substance such as carbon is added. In addition, when used for extrusion molding aimed at cost reduction, it is necessary to heat and extrude at a high temperature because it is a heat-resistant engineering plastic, which deteriorates the conductive material itself or promotes the decomposition reaction with the resin. In many cases, the decomposition gas remains in the belt material, and the appearance of the belt is deteriorated, and the bending resistance due to decomposition is extremely deteriorated.

  Since these resin-based belts all have a high tensile elastic modulus and are hard, a sufficient transfer area (also referred to as a transfer nip) cannot be obtained in the transfer of toner from the photoreceptor to the transfer belt (primary transfer). A transfer failure is likely to occur, and a phenomenon occurs in which toner remains on the photosensitive member side and accumulates and adheres. As a result, there is a problem in that the toner from the photosensitive member is not sufficiently transferred to the transfer belt, and the toner transfer efficiency at the primary transfer portion is likely to be extremely reduced.

  Further, when a hard belt having a high tensile elastic modulus is used, a strong pressure is applied to the toner layer sandwiched between the relatively hard transfer roller and the hard belt in the secondary transfer process, and the toner in the center of the toner Concentration of pressure on the layer is likely to occur, the toner layer in the center of the character is agglomerated and destroyed, and the toner is not transferred sufficiently (so-called character missing). Therefore, there is a problem that the transfer of toner is not sufficiently performed due to the hardness of the belt.

  A number of endless belts made of a flexible material such as rubber have been proposed as described above in order to improve toner transfer characteristics in the transfer of such a resin belt (Japanese Patent Laid-Open No. 9-54506).

  However, since the rubber belt is too flexible, it tends to stretch with respect to the tensile force in the circumferential direction of the belt, and there is a problem that image displacement occurs. Therefore, it is necessary to embed a material that is difficult to stretch such as a woven fabric inside the belt. There is a problem that thickness uniformity cannot be obtained because the thickness of the belt is inevitably increased.

  In addition, the rubber contains additives such as vulcanizing agents and plasticizers that tend to bleed, causing a problem of contaminating the photoreceptor. Furthermore, since it is a batch type production, it is difficult to reduce the cost and it is difficult to uniformly control the electrical resistivity in the semiconductive region by the conductive filler. There was also a problem that the resistance value changed by 2 to 3 orders due to the change.

  On the other hand, a belt using a thermoplastic elastomer instead of rubber, or a belt obtained by alloying a thermoplastic elastomer and a thermoplastic resin has been proposed (JP-A-8-99374, JP-A-10-6411, JP 2000-62993 A, JP 2001-13802 A, JP 2003-29537 A).

  Among these, in Japanese Patent Application Laid-Open Nos. 8-99374 and 10-6411, belts in which a thermoplastic resin and a thermoplastic elastomer are alloyed are proposed, but the dispersibility of the thermoplastic resin and the thermoplastic elastomer is proposed. This is because the resistance value has a large voltage dependency because the carbon tends to agglomerate, and the variation in the electrical resistivity tends to increase, and the electrical resistivity voltage dependency and the electrical resistance change due to temperature and humidity are also large, There was a problem that high-precision image quality could not be obtained under all use conditions. In addition, when incorporated in the image forming apparatus, there is a problem that the endless belt leaks due to application of a high voltage.

  In JP-A-2000-62993, the endless belt made of a thermoplastic elastomer having a low melting point has a problem in that it tends to stretch and an image shift occurs, and the endless belt made of a thermoplastic elastomer There is a problem in that the toner releasability is poor in the soft segment portion, and the toner transfer efficiency at the secondary transfer portion from the belt to the paper tends to deteriorate. In addition, since the flexibility is high, when the extrusion molding method is adopted, there is a problem that it is difficult to become a perfect circle, and a post-process such as heat treatment is required, which is expensive. Furthermore, since there are few crystal components, there existed a problem that it was inferior in chemical resistance, and changed in quality by the influence of the silicone oil etc. which generate | occur | produce from a fixing member.

Japanese Patent Application Laid-Open No. 2001-13802 proposes a belt that reduces elongation and combines softness with a laminated belt of a thermoplastic resin and a thermoplastic elastomer by extrusion molding. There was a problem that the belt resistance value varied because the disturbance of the flow characteristics of each molten resin affected the electrical resistivity of each layer. Further, since the surface layer is a thermoplastic elastomer, there is a problem that it has a small crystal component and is inferior in chemical resistance, and is deteriorated by the influence of silicon oil or the like generated from a fixing member or the like.
JP-A-63-311267 Japanese Patent Laid-Open No. 5-170946 JP-A-6-228335 JP-A-3-89357, etc. Japanese Patent Laid-Open No. 9-54506 JP-A-8-99374 Japanese Patent Laid-Open No. 10-6411 Japanese Unexamined Patent Publication No. 2000-62993 Japanese Patent Laid-Open No. 2001-13802 JP-A-60-170862 JP-A-3-89357 JP-A-4-313757 Japanese Patent Laid-Open No. 6-149083 JP 2003-29537 A Journal of Electrophotographic Society 33 (1) 43 (1994)

As described above, the conventional belt has the following problems for each material.
In the case of a belt made of a thermoplastic elastomer or a resin, a “curved crease” is likely to be attached to a portion that is bent by the roller while the belt is stopped. When the belt is bent and wrinkled, the image is naturally distorted.
In addition, the thermoplastic elastomer belt has a problem that toner releasability, dimensional accuracy, and voltage dependency of electrical resistance are large.
-Resin belts have problems of cracking and missing characters due to toner cohesive failure.
The rubber belt has a problem of cost, a large change in electrical resistivity due to temperature and humidity, and a problem of contamination of the photoreceptor due to bleeding such as a crosslinking agent and a plasticizer.

  As described above, there is no endless belt material that combines high image quality, high durability, high dimensional accuracy, and low cost in the conventionally proposed or commercialized endless belts. In most cases, humidity conditions are limited or printing paper is limited.

  Accordingly, an object of the present invention is to provide an image forming apparatus belt that has high image quality, high durability, high dimensional accuracy, and low cost, and that is free of temperature and humidity conditions of the image forming apparatus and printing paper, and the image forming apparatus belt. An object of the present invention is to provide an image forming apparatus using a belt for forming apparatus.

  That is, the object of the present invention is excellent in scratch resistance, flex resistance, chemical resistance, dimensional stability, electrical resistance and external environmental stability of these characteristics, and at low cost, high image quality and high durability are possible. An image forming apparatus belt and an image forming apparatus using the image forming apparatus belt are provided.

  In the process of repeatedly studying to achieve the above object, the present inventors first used a thermoplastic elastomer as a material that can be cost-reduced in that it can be extruded and can obtain flexibility. The image test was repeatedly performed while investigating the environmental dependence of the electrical resistance and the voltage dependence characteristics of the electrical resistance, paying particular attention to the surface roughness, surface wettability, and dispersion state of the conductive material.

  As a result, when a specific thermoplastic elastomer is used, the endless belt is difficult to be damaged; a conductive material dispersion having a specific tensile elastic modulus, surface roughness characteristics, surface wettability, and voltage dependency of electric resistance. It was found that the endless belt in the state is important for improving the toner transfer efficiency in the primary transfer portion and the toner transfer efficiency in the secondary transfer portion. Further, it has been found that a stable image can be formed under a wide range of temperature and humidity environments by using a specific conductive material. Furthermore, it has been found that an endless belt molded by a specific molding method is provided with high dimensional accuracy and low cost in addition to high image quality and temperature and humidity environment stability.

The present invention has been achieved based on such knowledge. The belt for an image forming apparatus according to claim 1 is an endless belt used in an image forming apparatus, and includes a thermoplastic polymer component including a thermoplastic elastomer. In a belt formed by molding a blend with a conductive material, the thermoplastic elastomer is a polyester polyester block copolymer in which the hard segment is an aromatic polyester and the soft segment is an aliphatic polyester, and the thermoplastic polymer The component contains 10% by weight or more of the thermoplastic elastomer, and the blend is formed by blending 1 to 20 parts by weight of a conductive substance with respect to 100 parts by weight of the thermoplastic polymer component, and measured at a voltage of 100V. The surface electrical resistivity is 1 × 10 ⁶ to 1 × 10 ¹⁴ Ω / □ and the volume resistivity is 1 × 10 ⁶ to 1 × 1. It is a range of 0 ¹³ Ω · cm, and variation in each electric resistivity is a maximum value / minimum value ≦ 100.

  Thus, as a thermoplastic elastomer, a belt using a thermoplastic elastomer made of a polyester polyester block copolymer in which a hard segment is an aromatic polyester and a soft segment is an aliphatic polyester is difficult to bend. Moreover, the belt using this thermoplastic elastomer is excellent in dimensional accuracy.

  The belt of the present invention has a relatively high surface electrical resistivity, a relatively low volume electrical resistivity, and a small variation in electrical resistivity. Therefore, the belt has excellent toner transfer from the photoreceptor to the belt, and from the belt to the paper. The toner has good transferability, and image quality deterioration due to wrinkles is prevented.

  The belt for an image forming apparatus according to claim 2 is the belt according to claim 1, wherein the thermoplastic elastomer has a crystal melting point of 190 ° C or higher and 220 ° C or lower and is measured by JIS K7210 (240 ° C, 2.16 kgf load). The flow rate (MFR) is 10 g / 10 min or more and 18 g / 10 min or less.

  A belt using a thermoplastic elastomer having such characteristics is easy to mold.

According to a third aspect of the present invention, there is provided a belt for an image forming apparatus according to the first or second aspect, wherein the surface electrical resistivity measured at an applied voltage of 100 V for 10 seconds is SR (100 V) and the applied voltage of 500 V is measured for 10 seconds. The resistivity is SR (500 V), the volume resistivity when measured at an applied voltage of 100 V for 10 seconds is VR (100 V), and the volume resistivity when measured at an applied voltage of 250 V for 10 seconds is VR (250 V). ), The following expressions (1), (2), and (3) are satisfied.
Formula (1): SR (100 V) / SR (500 V) <VR (100 V) / VR (250 V)
Formula (2): SR (100 V) / SR (500 V) ≦ 30
Formula (3): 8 ≦ VR (100 V) / VR (250 V) ≦ 100

  The fact that the belt for an image forming apparatus satisfies the above formula (1) means that the voltage dependency of the volume resistivity is larger than the voltage dependency of the surface resistivity. Further, satisfying the above formulas (2) and (3) indicates that the voltage dependency of the surface electrical resistivity is small and the voltage dependency of the volume electrical resistivity is moderately large.

  As described above, the voltage dependency of the volume resistivity is larger than the voltage dependency of the surface resistivity, and the voltage dependency of the volume resistivity is moderately large. At the time of the next transfer, the charge is moderately eliminated in the belt thickness direction, and as a result, the toner releasability effect by the self-discharge of the toner can be enhanced.

  A belt for an image forming apparatus according to a fourth aspect of the present invention is the belt for an image forming apparatus according to any one of the first to third aspects, wherein the tensile elastic modulus of the endless belt is not less than 300 MPa and not more than 2500 MPa, The surface roughness Ra is 0.05 μm or more and 0.3 μm or less.

  As described above, the belt having a tensile elastic modulus of 300 MPa or more and 2500 MPa or less is moderately soft, exhibits an effect of scraping the toner from the photosensitive member in the primary transfer portion, and is applied to uneven paper in the secondary transfer portion. Toner transfer efficiency can be improved. Furthermore, the surface wettability represented by the contact angle with water is within a suitable range of 60 ° or more and less than 90 °, which is neither hydrophilic nor hydrophobic, so that the toner transfer efficiency in the primary transfer portion is improved. Further, the toner releasability in the secondary transfer is supplemented by the electrical characteristics defined in claim 3 and the elastic characteristics defined in claim 4, resulting in the primary toner. Secondary transfer efficiency can be improved.

  Further, it is effective for improving the toner transfer efficiency in the primary transfer and the secondary transfer that the surface roughness of the endless belt is moderately rough at 0.05 to 0.3 μm in Ra.

  That is, the present inventors will examine the tensile elastic modulus, surface wettability, surface roughness, and toner transfer efficiency of an endless belt using an alloy material of a thermoplastic resin and a thermoplastic elastomer. The adhesion between the toner and the transfer belt in the next transfer portion and the toner transferability were examined.

As the adhesive force in the secondary transfer part between the toner and the transfer belt,
B) Intermolecular attractive force acting between the transfer belt and toner particles, so-called van der Waals force b) Mirror force that the charged toner acts electrically c) Generated by the contact between the toner and the transfer belt Contact band power d) In general, the liquid bridging force due to moisture between the toner and the transfer belt is considered, and the toner transfer conditions in the secondary transfer part are the total adhesion force of a) to d). It is said that it is at least essential as a toner transfer condition to apply a reverse electric field to the toner and to apply a Coulomb force so as to overcome it.

Therefore, the following can be considered as conditions for reducing the adhesion between the belt and the toner in the secondary transfer portion.
E) When the belt surface is appropriately roughened, the van der Waals force is reduced and the toner adhesion force on the transfer belt can be reduced, which contributes to the improvement of the secondary transfer efficiency.
F) The low electric resistivity of the transfer belt facilitates the charge removal of the toner charged on the transfer belt, which is advantageous for improving the secondary transfer efficiency.
G) A small difference in the triboelectric charging train between the toner and the transfer belt is effective in reducing the contact band power.
H) The transfer belt surface being hydrophobic has the effect of reducing the liquid crosslinking force and the toner adhesion.

  In other words, in order to improve the secondary transfer efficiency, it is generally considered that the above measures e) to h) are effective. On the other hand, in the primary transfer, these measures are all counterproductive. Become.

Accordingly, the present inventors have proposed that the belt functions necessary for improving the toner transfer efficiency in the primary transfer and the secondary transfer are shared. In other words, in the toner transfer, it may be better to give mechanical force other than electrostatic Coulomb force, that is, adhesion.
・ To reduce the toner adhesion in secondary transfer, the toner adhesion can be reduced by making a belt with electrical resistance that has a self-removal function (that is, the volume electrical resistivity has an appropriate voltage dependency). Reduce
・ Improves toner adhesion in primary transfer by improving the toner adhesion by softening the belt material and making the belt surface as hydrophobic as possible.
These combinations are considered to be able to improve the toner transfer efficiency of primary transfer and secondary transfer at the same time, and focus on thermoplastic elastomer as a means to adjust the elastic modulus without impairing the mechanical strength of the transfer belt. The alloying of the thermoplastic elastomer and the thermoplastic resin is examined, the specific electric resistance voltage dependency satisfying the above formulas (1) to (3), and further, the appropriate elastic modulus and the appropriate surface wettability It has been clarified that satisfying the surface roughness improves the primary transfer efficiency and the secondary transfer efficiency.

  The belt for an image forming apparatus according to claim 5 is the belt according to any one of claims 1 to 4, wherein the thermoplastic polymer component is further blended with a thermoplastic resin, and a weight ratio of the thermoplastic elastomer to the thermoplastic resin is , Thermoplastic elastomer / thermoplastic resin = 10/90 to 90/10.

  According to a sixth aspect of the present invention, in the image forming apparatus belt according to the fifth aspect, the weight ratio of the thermoplastic elastomer to the thermoplastic resin is thermoplastic elastomer / thermoplastic resin = 20/80 to 80/20. To do.

  According to a seventh aspect of the present invention, in the image forming apparatus belt according to the fifth or sixth aspect, the thermoplastic resin contains polyalkylene terephthalate as a main component.

  An image forming apparatus belt according to an eighth aspect is characterized in that, in the seventh aspect, the polyalkylene terephthalate is polybutylene terephthalate (PBT).

  According to a ninth aspect of the present invention, in the image forming apparatus belt according to the seventh or eighth aspect, the polyalkylene terephthalate contains a polymerization catalyst.

  A belt for an image forming apparatus according to a tenth aspect is the belt according to any one of the first to ninth aspects, wherein the blend is further a melt flow rate (MFR) of 0.01 g according to JIS K7210 (190 ° C., 2.16 kgf load). A thickener comprising a polymer having a value in the range of / 10 minutes to 10 g / 10 minutes is contained in an amount of 0.01 parts by weight to 20 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component.

  An image forming apparatus belt according to an eleventh aspect is characterized in that, in the tenth aspect, the thickener is a polymer containing an epoxy group or a glycidyl methacrylate group.

  If the thermoplastic polymer material contains a thermoplastic elastomer that satisfies the requirements of these claims 5 to 11 and, if necessary, a thermoplastic resin, a belt having good durability and an appropriate elastic modulus can be obtained. While satisfy | filling the electrical property of this invention, favorable extrusion moldability can be obtained.

The image forming apparatus belt according to claim 12, in any one of claims 1 to 11, as a conductive material, DBP oil absorption of 50 cm ^3/100 g or more 300 cm ^3/100 g or less and a specific surface area of ^35m 2 / g or more 500m ² / g or less, a carbon black having a volatile content of 0% to 20% and an average primary particle size of 20 nm to 50 nm is blended so as to satisfy the following formulas (i) and (ii).
Formula (i): LogY ≧ −X + 20
Formula (ii): LogY ≦ −X + 30
However, X and Y are as follows.
X: Carbon black content (% by weight) in the endless belt
Y: Surface electrical resistivity (Ω) at 100 V applied voltage, 10 seconds for endless belt

  By blending carbon black so as to satisfy the above requirements as a conductive substance, good temperature and humidity environment stability and uniformity of electrical resistivity can be obtained.

  A belt for an image forming apparatus according to a thirteenth aspect has a melt viscosity represented by a melt flow rate (MFR) according to JIS K7210 (240 ° C., 2.16 kgf load) according to any one of the first to twelfth aspects of 1 g / 10. It is characterized by being formed by extruding a molding material of at least 10 g / 10 min.

  A belt for an image forming apparatus according to a fourteenth aspect is characterized in that the belt for an image forming apparatus according to any one of the first to thirteenth aspects is formed by pulling a molten tube heated and extruded from an annular die while cooling or solidifying it. .

  According to a fifteenth aspect of the present invention, in the image forming apparatus belt according to the fourteenth aspect, a plurality of temperature adjusting mechanisms are provided in the circumferential direction of the annular die.

  A belt for an image forming apparatus according to a sixteenth aspect is the one according to the fourteenth or fifteenth aspect, wherein the melting tube is cooled by contacting a mold whose temperature is adjusted to a range of 30 to 150 ° C inside or outside the melting tube. And

  According to a seventeenth aspect of the present invention, in the image forming apparatus belt according to any one of the fourteenth to sixteenth aspects, the melting tube is pulled out while maintaining a cylindrical shape.

  In this way, the endless belt obtained by extruding the tube extruded from the annular die by continuous extrusion in an annular state and pulling it as a cylindrical body, and cutting it into a ring, reduces cost and dimensional stability. Can be achieved at the same time. Further, by providing a plurality of temperature adjusting mechanisms in the circumferential direction of the annular die, an endless belt with little variation in electrical resistivity can be manufactured at low cost.

  The belt for an image forming apparatus of the present invention is particularly suitable for a seamless intermediate transfer belt, a conveyance transfer belt, a transfer fixing belt, a fixing belt, a photosensitive belt, or a development sleep.

  The image forming apparatus of the present invention includes such a belt for an image forming apparatus of the present invention.

  Embodiments of an image forming apparatus belt and an image forming apparatus according to the present invention will be described in detail below.

[I] Endless belt material The endless belt of the present invention comprises a thermoplastic polymer component and a conductive substance. This thermoplastic polymer component is a thermoplastic elastomer blended with a thermoplastic resin or the like as required. Hereinafter, each compounding material will be described in terms of items.

(1) Thermoplastic Elastomer The thermoplastic elastomer used in the present invention comprises a polyester polyester block copolymer using an aromatic polyester for the hard segment and an aliphatic polyester for the soft segment.

  The characteristics of this thermoplastic elastomer are that the endless belt is not easily scratched; the crack resistance of the endless belt is greatly increased; and an appropriate flexibility can be imparted to the endless belt.

  More specifically, the polyester polyester block copolymer includes (a) an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, (b) an aromatic dicarboxylic acid or an alkyl ester thereof, and (c). A polyester oligomer obtained by condensing an aliphatic or alicyclic dicarboxylic acid and an aliphatic diol, and (d) a polyester oligomer synthesized from an aliphatic lactone or an aliphatic monool carboxylic acid as a raw material, an esterification reaction, or This is a product obtained by polycondensing an oligomer obtained by a transesterification reaction.

  Examples of the aliphatic and / or alicyclic diol having 2 to 12 carbon atoms in (a) include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,4-cyclohexanediol, and 1,4. -Cyclohexanedimethanol etc. are mentioned, Preferably, it is what has 1, 4- butanediol and ethylene glycol as a main component, and what used these 1 type or 2 types or more together can be used.

  Examples of the aromatic dicarboxylic acid (b) include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and the like, preferably, terephthalic acid, 2,6-naphthalenedicarboxylic acid as a main component, Two or more of these may be used in combination. Examples of the alkyl ester of aromatic dicarboxylic acid include dimethyl esters such as dimethyl terephthalate, dimethyl isophthalate, dimethyl phthalate, and 2,6-dimethyl naphthalate, preferably dimethyl terephthalate and 2,6-dimethyl naphthalate. There may be a combination of two or more of these. In addition to the above, trifunctional diols, other diols and other dicarboxylic acids and esters thereof may be copolymerized in small amounts, and aliphatic dicarboxylic acids such as adipic acid or alicyclic dicarboxylic acids, or What uses alkylester etc. as a copolymerization component is also good.

  Examples of the above (c) include 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, alicyclic dicarboxylic acid such as dicyclohexyl-4,4′-dicarboxylic acid, or succinic acid, oxalic acid, adipic acid And polyester oligomers having a structure in which one or more aliphatic dicarboxylic acids such as sebacic acid are condensed with one or more diols such as ethylene glycol, propylene glycol, tetramethylene glycol, and pentamethylene glycol.

  Examples of the above (d) include polycaprolactone-based polyester oligomers synthesized from ε-caprolactone, ω-oxycaproic acid and the like.

  This thermoplastic elastomer has a crystal melting point of 190 ° C. or higher and 220 ° C. or lower, and a melt flow rate (MFR) according to JIS K7210 (240 ° C., 2.16 kgf load) of 10 g / 10 min or more and 18 g / 10 min or less. Preferably there is.

  If the crystalline melting point is lower than 190 ° C., it becomes too soft and the belt will stretch when tension is applied to the belt. If the crystal melting point is higher than 220 ° C., the belt becomes too hard, the belt is easily cracked, sufficient mechanical durability is difficult to obtain, and the resistance to roller wrinkles is also deteriorated.

  When the MFR is lower than 10 g / 10 min, kneading works well when kneading a conductive material such as carbon black and dispersibility is improved. However, since melt viscosity is increased, it is added to the material during molding processing. Since the shear stress becomes too high, the material generates heat and may deteriorate due to heat, which is not preferable. If it is higher than 18 g / 10 minutes, the melt viscosity is low, so that kneading does not work easily and the dispersibility of the conductive material is deteriorated, which is not preferable.

(2) Thermoplastic resin The thermoplastic polymer component used in the endless belt of the present invention may contain a thermoplastic resin in addition to the thermoplastic elastomer.

  When alloying a thermoplastic resin and a thermoplastic elastomer, if the thermoplastic resin and the thermoplastic elastomer have a common functional group, such as a high affinity between them, the alloy dispersibility of the thermoplastic resin and the thermoplastic elastomer The crack resistance is improved drastically and the tensile elastic modulus can be adjusted, and excellent surface smoothness and conductive material dispersibility such as carbon black can be obtained.

  Therefore, as the thermoplastic resin, PAT (polyalkylene terephthalate) is preferable, and PBT (polybutylene terephthalate) and PET (polyethylene terephthalate) are more preferable. PBT is particularly preferable because it has a high crystallization rate, so that there is little change in crystallinity depending on molding conditions, and it is generally stable at a crystallinity of around 30%.

  Moreover, the thermoplastic resin used for this invention can also introduce | transduce a copolymerization component in the range which does not impair the effect of this invention remarkably. Specific examples include those in which an ester bond is a main chain and an ester bond such as polymethylene glycol is introduced.

  As the molecular weight of the thermoplastic resin, a resin having a general molecular weight such as a weight average molecular weight of 10,000 to 100,000 can be used. However, when there is a demand for high mechanical properties such as tensile elongation at break, a high molecular weight is required. Molecular weight is preferred. Specifically, it is preferably 20,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more.

[Weight ratio of thermoplastic resin to thermoplastic elastomer]
The weight ratio of the thermoplastic resin to the thermoplastic elastomer in the thermoplastic polymer used for the molding material of the endless belt of the present invention is preferably 10/90 to 90/10, particularly preferably 80/20 to 20/80, and 60/40. ˜40 / 60 is particularly preferred. If there is more thermoplastic elastomer than this range and less thermoplastic resin, the belt becomes too soft, and when the belt tension is applied, the belt stretches and the toner image is disturbed. On the other hand, if the amount of thermoplastic elastomer is small and the amount of thermoplastic resin is large, the belt becomes too hard and cracks are likely to occur, and the wrinkles of the roller are liable to occur.

[Difference in viscosity between thermoplastic resin and thermoplastic elastomer]
If the difference in viscosity between the two materials is too large, even if the production conditions are adjusted, good dispersibility of the conductive substance may not be obtained and uniform dispersion may not be achieved. . Specifically, the ratio of the thermoplastic resin and the thermoplastic elastomer measured by MFR under the same conditions is preferably within a range of about 1/20 to 20/1, and should be within a range of 1/10 to 10/1. More preferred.
Further, the MFR of the thermoplastic resin is preferably smaller than the MFR of the thermoplastic elastomer from the viewpoint of dispersibility of the conductive material, and particularly preferably 1/2 or less.

  In addition, it is preferable to select the conditions close | similar to the processing temperature of a thermoplastic resin composition as measurement temperature conditions based on JISK7210 as a measuring method of MFR. For example, when PBT and polyester elastomer are selected, it is preferable to set a processing temperature of 240 ° C. as the measurement temperature and compare the difference in viscosity between the two materials. Moreover, it can measure suitably by selecting 2.16 kg, for example as a load.

(3) Polymerization catalyst When the thermoplastic polymer as a belt molding material is composed of a thermoplastic resin and a thermoplastic elastomer, these are simply mixed, mixed from the polymerization stage, and mixed while reacting the catalyst. Although known alloying techniques such as those obtained can be used, those obtained by heating and mixing using a polymerization catalyst are most preferred from the viewpoint of cost.
The polymerization catalyst may be contained in the thermoplastic resin. For example, a catalyst remaining in the polyalkylene terephthalate as a catalyst for synthesizing polyalkylene terephthalate may be used as a polymerization catalyst for a thermoplastic resin and a thermoplastic elastomer.

  Of the polymerization catalysts, Ti-based polymerization catalysts are preferred, and alkyl titanates can be suitably used.

  Among the alkyl titanates, tetrabutyl titanate or tetrakis (2-ethylhexyl) orthotitanate is preferable, and these are easily available as TYZOR TOT (manufactured by DuPont) or TYZOR TBT (manufactured by DuPont).

  In addition, the Ti-based polymerization catalyst is preferably combined with an alkali metal, alkaline earth metal-containing compound or zinc-containing compound because it works more effectively, and it is particularly preferable to have a magnesium-containing compound as the polymerization catalyst.

  The compound containing magnesium is not particularly limited, but an organic acid magnesium salt is particularly preferable, and magnesium acetate is particularly preferable.

  If the content of the polymerization catalyst is too small, it may not work effectively, so it is preferable that the content is high to some extent. Specifically, the mass of the metal in the polymerization catalyst is the total thermoplastic polymer component (thermoplastic resin and heat 1 ppm or more is preferable with respect to the total of the plastic elastomer), more preferably 10 ppm or more, and particularly preferably 20 ppm or more. On the other hand, since ester resins are known to cause depolymerization in the presence of a large amount of heavy metals, it is preferable that they are small to some extent, specifically 10,000 ppm or less, more preferably 1000 ppm or less. 500 ppm or less is particularly preferable. In the following, the weight ratio of Ti and Mg of the polymerization catalyst to the total thermoplastic polymer components may be referred to as “Ti concentration” and “Mg concentration”.

(4) Chelator If the activity of the polymerization catalyst is too high, depolymerization of the thermoplastic polymer component may be promoted, resulting in problems such as deterioration of mechanical properties due to molecular weight reduction and foaming due to the generation of low molecular weight substances. When a chelator having the ability to chelate the metal in the catalyst is present, depolymerization can be suppressed, and therefore it is preferable to use a chelator as necessary.

  There is no restriction | limiting in particular as a kind of chelator, A well-known chelator can be used.

  Examples include phosphites, phosphates, phosphates, and hydrazines, such as Irgafos 168 (manufactured by Ciba Geigy Japan), PEP36 (manufactured by Asahi Denka Kogyo Co., Ltd.). Sandstub P-EPQ (manufactured by Clariant Japan Co., Ltd.), phosphite ester, IRGANOX MD1024 (manufactured by Nippon Ciba-Geigy Co., Ltd.), CDA-6 (manufactured by Asahi Denka Kogyo Co., Ltd.), etc. It can be obtained from the market.

  In the present invention, by suppressing the depolymerization and low molecular weight generation by optimizing the molding conditions, it is possible to add no chelator, but when it is necessary to suppress the depolymerization, the addition amount of the chelator is the total heat It is preferable to add 0.001 part by weight or more with respect to 100 parts by weight of the plastic polymer component, and it is preferable to add 0.1 part by weight or more in order to obtain a better effect.

  If the amount of the chelator is too large, the polymerization catalyst loses its activity and an endless belt having good physical properties may not be obtained. Therefore, it is preferable not to add too much, and 10 parts by weight with respect to 100 parts by weight of the total thermoplastic polymer component. The following is preferable, and the amount is further preferably 5 parts by weight or less.

  In general, it is preferable to use a chelator as a small amount of 0.1 parts by weight or less with respect to 100 parts by weight of the total thermoplastic polymer component. As an example of preferred usage, the polymerization catalyst is added in an amount as large as 50 to 500 ppm, and the chelator is also used in an amount of 0.1 to 3 parts by weight, preferably 0.3 to 1 part by weight, higher than common sense. By optimizing the molding conditions (temperature, residence time, etc.) to obtain the endless belt, depolymerization can be suppressed while promoting the formation of chemical bonds and increase in molecular weight between the thermoplastic resin and the thermoplastic elastomer, and unprecedented physical properties. An excellent endless belt can be obtained.

(5) Thickener The thickener is preferably blended in order to provide an endless belt that exhibits the surface electrical resistivity with a small dependence on applied voltage, which is the object of the present invention. In other words, in the endless belt using a thermoplastic resin / thermoplastic elastomer / conductive material compounding material to which no thickener is added, the applied voltage dependency on the surface electrical resistivity is very large. Cannot be obtained. The cause is that the viscosity difference between the high viscosity thermoplastic resin and the low viscosity thermoplastic elastomer is large, so the low viscosity thermoplastic elastomer does not mix well with other components during kneading, and each of the endless belts It is considered that the dispersion of the components is bad. In order to solve this problem, in the present invention, the viscosity of the entire thermoplastic resin / thermoplastic elastomer / conductive material mixture system is increased, and each component is sufficiently contained even if a considerable amount of low-viscosity thermoplastic elastomer is contained. For the purpose of increasing the viscosity to be dispersible, it is preferable to add a thickener.

  The thickener used in the present invention is preferably a polymer having a melt flow rate (MFR) according to JIS K7210 (190 ° C., 2.16 kgf load) in a range of 0.01 to 10 g / 10 min, more preferably 0. A polymer exhibiting an MFR of 0.05 to 5 g / 10 min, particularly preferably 0.1 to 3 g / 10 min. If the MFR is less than 0.01 g / 10 minutes, the viscosity becomes too high to be kneaded, and if it exceeds 10 g / 10 minutes, the viscosity of the thickener is too low and the thickening effect cannot be sufficiently obtained.

  Examples of thickeners used in the present invention include polymers containing epoxy groups such as glycidyl methacrylate groups. Since the epoxy group has high reactivity, a high molecular weight is generated by reaction with a thermoplastic resin or a thermoplastic elastomer at the time of resin kneading, and the thickening effect is very large. Specific examples of the polymer containing an epoxy group include Modiper A4200 in which PMMA is graft-polymerized on an ethylene-glycidyl methacrylate copolymer (EGMA) and Modiper A4400 in which acrylonitrile-styrene copolymer (AS) is graft-polymerized on EGMA (both , Manufactured by Nippon Oils and Fats).

  The addition amount of the thickener is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the total thermoplastic polymer component. Parts, most preferably 0.1 to 5 parts by weight. If the addition amount of this thickener is less than 0.01 parts by weight, a sufficient thickening effect cannot be obtained, and if it exceeds 20 parts by weight, the viscosity becomes too high to be kneaded.

(6) Conductive material The conductive material is not particularly limited as long as it satisfies the performance required for the application, and various materials can be used. Specifically, carbon black is used as the conductive filler. Carbon fillers such as carbon fiber, graphite, metal conductive fillers, metal oxide conductive fillers, etc. are used, and in addition to conductive fillers, ion conductive substances such as quaternary ammonium salts are exemplified. However, among these conductive materials, it is preferable to use carbon black because the humidity dependence of the electrical resistivity tends to be reduced. Carbon black may be used in combination with an ion conductive substance.

In the present invention, DBP oil absorption amount as the carbon black for the following reasons 50~300cm ³ / 100g, a specific surface area 35~500m ² / g, volatile content 0-20%, carbon black is used to satisfy the average primary particle size 20~50nm It is preferable.

1) About the DBP oil absorption amount of carbon black The larger the DBP oil absorption amount of carbon black, the easier it is for carbon to form a bead-like chain (carbon structure), and the advantage that carbon agglomerates are less likely to occur, and the addition amount is small. However, on the other hand, the carbon chain was broken by various shearing forces applied to the resin containing carbon black in the process from compounding to molding, and the electrical resistivity was reduced. However, there is a problem that the fluctuations are not stable.
On the other hand, if the DBP oil absorption amount of carbon black is too small, it is difficult to form a carbon chain, so that the amount of carbon added for expressing conductivity is excessively increased, and there is a problem that the flex resistance of the material is impaired.
Thus preferred DBP oil absorption of carbon black is 50~300cm ³ / 100g.

2) About the particle size and specific surface area of carbon black The larger the specific surface area of carbon black, the more electrically conductive it appears with less added weight, so the mechanical strength is more advantageous in terms of resistance to cracking, but depending on the amount of carbon added. Since the conductivity tends to change abruptly, it is necessary to have a blending accuracy within ± 0.05% in order to control to the semiconductive region, and the resistance variation of the endless belt must be made uniform within ± 1 order. difficult. In addition, since carbon black with a large specific surface area generally has a small particle size, when dispersed in a resin, the carbon black particles are likely to be fooled. As a result, carbon aggregates are mixed in the molded product, and the location of the carbon aggregates Electricity concentrates on the surface, and partial dielectric breakdown is likely to occur. Also, if the specific surface area of carbon black is too small (carbon particles are too large), it is difficult to form carbon aggregates, so the appearance of the molded product is smooth, but the electrical conductivity is easily affected by the contact between the carbon particles. Since the resistivity tends to vary, it is preferable to select an optimized carbon particle size.
Accordingly, the average primary particle size of carbon black is preferably 20 to 50 nm, and the specific surface area is 35 to 500 m ² / g.

3) About the volatile matter of carbon black The more the volatile matter of carbon black, the better the carbon dispersion due to its surface characteristics, but it is more disadvantageous in molding because it generates gas during heating and kneading. Conversely, the smaller the volatile content of carbon black, the less the gas is generated during heating and kneading, so the moldability is better, but the carbon dispersion tends to deteriorate.
Therefore, the preferable volatile content of carbon black is 0 to 20%.

  There are no particular restrictions on the type of carbon black as long as it satisfies the DBP oil absorption, specific surface area, volatile content, and average primary particle size, and two types of carbon black can be used. It may be above.

  For example, as the type of carbon black, acetylene black, furnace black, channel black, and the like can be suitably used, and among these, acetylene black that has few functional groups as impurities and hardly causes poor appearance due to carbon aggregation can be particularly suitably used. . Moreover, there is no problem even if carbon black subjected to a known post-treatment step such as resin-coated carbon black, heat-treated carbon black, graphitized carbon black, or acid-treated carbon black is used.

  Furthermore, carbon black treated with a coupling agent such as silane, aluminate, titanate, and zirconate may be used for the purpose of improving dispersibility and suppressing gas generation.

In the present invention, the content of carbon black in the endless belt (hereinafter sometimes referred to as “carbon black concentration”) satisfies the following formulas (i) and (ii). This is preferable because the influence on the surface is reduced.
Formula (i): LogY ≧ −X + 20
Formula (ii): LogY ≦ −X + 30
However, X and Y are as follows.
X: Carbon black content (% by weight) in the endless belt
Y: Surface electrical resistivity (Ω) at 100 V applied voltage, 10 seconds for endless belt

That is, for example, in the case of a belt having a surface electrical resistivity of 1 × 10 ⁶ (Ω), the carbon black concentration is 14 to 24% by weight, and in the case of a belt having a surface electrical resistivity of 1 × 10 ¹⁰ (Ω). Has a carbon black concentration of 10 to 20% by weight, and in the case of a belt having a surface electrical resistivity of 1 × 10 ¹⁴ (Ω), a carbon black concentration of 6 to 16% by weight This is preferable in that it can be an endless belt with little variation in electrical resistivity against environmental variation at low humidity.

X and Y are particularly logY ≧ −X + 21
logY ≦ −X + 29
It is preferable that

  If the carbon black concentration is higher than the above range, the appearance of the product deteriorates due to the generation of decomposition gas etc. of the carbon black itself, and the resin is decomposed by the reaction between the carbon black and the resin, and scratches derived from foaming are generated. Therefore, it is not preferable in appearance. Further, the folding resistance is also deteriorated.

  If the carbon black concentration is lower than the above range, the conductivity cannot be expressed, the carbon black dispersion state becomes rough, the electric resistivity tends to vary, and the contact resistance is greatly influenced by the environment. When mounted as an endless belt in an image forming apparatus, an image abnormality may occur depending on the environment.

(7) Additional compounding material; optional component In the endless belt of the present invention, any compounding component 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 agent, a crosslinking aid, a colorant, a flame retardant, and a dispersant can be added.

  Furthermore, compounding materials such as various thermoplastic resins, various elastomers, thermosetting resins, and fillers can be blended as the second and third components within a range that does not significantly impair the effects of the present invention.

  Thermoplastic resins include polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex components such as ethylene / propylene copolymer rubber, styrene Butadiene rubber, styrene / butadiene / styrene styrene block copolymer or its hydrogenated derivatives, polybutadiene, polyisobutylene, polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, polyimide, liquid crystalline polyester, polysulfone, polyphenylene sulfide, poly Bisamidotriazole, polyetherimide, polyetheretherketone, acrylic, polyfluorinated vinylidene, polyfluorinated vinyl, chlorotrifluoroethylene, ethylene Lafluoroethylene copolymer, hexafluoropropylene, perfluoroalkyl vinyl ether copolymer, acrylic acid alkyl ester copolymer, polyester ester copolymer, polyether ester copolymer, polyether amide copolymer, polyurethane copolymer What consists of 1 type, such as coalescence, or these mixtures can be used.

  As a thermosetting resin, what consists of 1 type, such as an epoxy resin, a melamine resin, a phenol resin, unsaturated polyester resin, or these mixtures, for example can be used. Examples of various fillers include calcium carbonate (heavy and light), talc, mica, silica, alumina, aluminum hydroxide, zeolite, wollastonite, diatomaceous earth, glass fiber, glass beads, bentonite, asbestos, and hollow. Glass ball, graphite, molybdenum disulfide, titanium oxide, carbon fiber, aluminum fiber, styrene steel fiber, brass fiber, aluminum powder, wood powder, rice husk, graphite, metal powder, conductive metal oxide, organometallic compound, organic In addition to fillers such as metal salts, additives such as antioxidants (phenolic, sulfur, phosphate ester, etc.), lubricants, various organic and inorganic pigments, UV inhibitors, antistatic agents, dispersants, neutralization Agents, foaming agents, plasticizers, copper damage inhibitors, flame retardants, crosslinking agents, flowability improvers, and the like.

[II] Manufacturing method of endless belt [heat kneading and molding]
In the present invention, a thermoplastic elastomer and a conductive material, and if necessary, a thermoplastic resin may be heated and kneaded to form a thermoplastic resin composition, and then an endless belt may be formed. The thermoplastic elastomer and the conductive material are further required. Accordingly, the endless belt may be formed by heating and kneading with a thermoplastic resin.

  In this case, the kneading conditions are adjusted so that the desired surface electrical resistivity can be obtained by either heat kneading in the stage of obtaining the thermoplastic resin composition or heat kneading in the stage of molding the resin composition into an endless belt. To do. In any case, since sufficient dispersion is not possible unless it is in a molten state, it is preferable that the heating temperature be higher to some extent. Specifically, using the melting point of the crystalline resin as a guideline, it should be equal to or higher than the melting point of the crystalline resin. Is preferable, and it is more preferable that it is melting | fusing point +10 degreeC or more. Further, if the heating temperature is too high, thermal decomposition may be caused and physical properties may be deteriorated. Specifically, using the melting point of the crystalline resin as a guide, the melting point of the crystalline resin is preferably + 80 ° C. or lower, more preferably the melting point + 60 ° C. or lower.

  In addition, it is preferable to dry the raw material before drying by heating since the raw material may be dried to obtain an endless belt having better physical properties. In some cases, the mixture may be heat-kneaded to obtain a thermoplastic resin composition, and after heat treatment at a melting point or lower to form an ester bond, it may be formed into an endless belt.

  In the present invention, a certain dispersion state of the thermoplastic elastomer and the thermoplastic resin creates a good dispersion of the conductive material of the endless belt and an appropriate roughness of the surface. It is considered that an excellent endless belt can be obtained. Accordingly, since the temperature during heat kneading and the time for receiving heat are important, it is desirable to set the heat kneading conditions while grasping the dispersion form of the obtained endless belt. At that time, the index of the alloy state is the voltage dependency characteristic of the electrical resistivity, the variation of the electrical resistivity, and the ratio of the surface electrical resistivity and the volume electrical resistivity.

  There is no particular limitation on the heating and kneading means, and a known technique can be used. For example, if a thermoplastic resin, a thermoplastic elastomer, a conductive material, and other additive components blended as necessary are first heat-kneaded to form a resin composition, a single-screw extruder, a twin-screw kneading extruder , Banbury mixer, roll, brabender, plastograph, kneader and the like can be used.

  In particular, a thermoplastic resin, a thermoplastic elastomer, a conductive material, and other additive components blended as necessary are mixed by, for example, a twin-screw kneading extruder, pelletized, and then molded into an endless belt Is particularly preferably used.

  The molding method is not particularly limited, and a belt that employs a known method such as a continuous melt extrusion molding method, an injection molding method, a blow molding method, an inflation molding method, a centrifugal molding method, or a rubber extrusion molding method. Particularly desirable is the continuous melt extrusion process. In particular, an extrusion molding method in which a molten tube extruded from an annular die is drawn while being cooled or cooled and solidified is preferable, and a downward extrusion type internal cooling mandrel method or a vacuum sizing method capable of controlling the inner diameter of the tube with high accuracy is particularly preferable. In particular, an endless belt with a seamless internal cooling mandrel system can be easily obtained, so that it is most preferable as a method for forming a belt for an image forming apparatus. In this case, the annular die is preferably provided with a plurality of temperature adjusting mechanisms in the circumferential direction. The melting tube is preferably cooled by bringing a mold whose temperature is adjusted in the range of 30 to 150 ° C. into contact with the inside or the outside, and in this way, the melting tube is taken up while maintaining the cylindrical shape. It is preferable.

  In this case, the molding material preferably has a melt viscosity represented by a melt flow rate (MFR) according to JIS K7210 (240 ° C., 2.16 kgf load) of 1 g / 10 min to 10 g / 10 min. If the melt viscosity of the molding material is less than 1 g / min MFR, the fluidity at the time of extrusion molding is poor, and in addition to the difficulty of extrusion molding, the shear stress applied to the molten resin is increased, making it difficult to adjust the resistance. However, if the melt viscosity of the molding material is excessively high, the melt tension is low, and it is difficult to maintain the tube state from the melted state until it is cooled and solidified. It is preferably 8 g / 10 minutes. Therefore, it is preferable to adjust the viscosity with a thickener as necessary so that such a melt viscosity can be obtained.

In addition, once a film with creases is produced by the inflation molding method, there is no problem even if it is used as an endless belt in a state in which the creases are not visible in post-processing. It can be an endless belt with seams.
However, as the take-up means, a molding method is preferable in which the endless tube is taken up while being flattened without being flattened.

  Since an endless belt with better physical properties can be obtained by optimizing the molding temperature, residence time, and the like, it is preferable to adjust the conditions according to each formulation.

[Heat treatment]
By heat-treating the endless belt thus obtained, an endless belt with improved physical properties can be obtained. In particular, the number of folding times and the tensile elastic modulus are improved.

  Although the heat treatment conditions depend on the raw material resin used, the temperature is usually 60 to 200 ° C., preferably 70 to 120 ° C. for 5 to 60 minutes, preferably about 10 to 30 minutes.

  The heat treatment of the endless belt may be performed by applying heat while driving the belt while being stretched around two or more rollers, or may be performed by attaching an endless belt to a cylindrical mold. Furthermore, the heat treatment may be performed in a cylindrical shape.

[III] Physical properties of endless belts [surface electrical resistivity and volume electrical resistivity]
The belt for an image forming apparatus of the present invention is
SR (100 V) is the surface electrical resistivity measured at an applied voltage of 100 V for 10 seconds.
SR (500V), the surface electrical resistivity measured at an applied voltage of 500V for 10 seconds,
The volume resistivity when measured at an applied voltage of 100 V for 10 seconds is VR (100 V),
The volume resistivity when measured at an applied voltage of 250 V for 10 seconds is VR (250 V),
In this case, the following expressions (1), (2) and (3) are satisfied.
Formula (1): SR (100 V) / SR (500 V) <VR (100 V) / VR (250 V)
Formula (2): SR (100 V) / SR (500 V) ≦ 30
Formula (3): 8 ≦ VR (100 V) / VR (250 V) ≦ 100

  That is, the rate of change represented by the maximum / minimum value (MAX / MIN) of the surface electrical resistivity measured at an applied voltage of 100 to 500 V (hereinafter sometimes referred to as “surface electrical resistance rate of change”) SR ( 100V) / SR (500V) is 30 times or less and the change rate represented by MAX / MIN of the volume resistivity measured at an applied voltage of 100 to 250V (hereinafter sometimes referred to as "volume resistivity change rate"). The relationship between the surface electrical resistance change rate SR (100 V) / SR (500 V) and the volume electrical resistance change rate VR (100 V) / VR (250 V) when VR (100 V) / VR (250 V) is 8 to 100 Is surface electrical resistivity <volume electrical resistivity, that is, SR (100 V) / SR (500 V) <VR (100 V) / VR (250 V).

  The characteristic that the rate of change in surface electrical resistance is small is important in that the toner is uniformly transferred even when the voltage applied by a roller or the like is changed. This is because the charged toner remaining on the belt that has not been subjected to the secondary transfer can be easily cleaned by the self-removing cleaning member, and the toner transfer efficiency on the belt during the secondary transfer can be improved. is there.

  The preferred surface electrical resistance change rate SR (100 V) / SR (500 V) is within 10 times, and the relationship between the volume electrical resistance change rate VR (100 V) / VR (250 V) is twice the surface electrical resistance change rate. It is preferable that the volume electric resistance change rate or less. The lower limit of the surface electrical resistance change rate is not particularly limited, but is usually about 1.5.

  In addition, if the volume electric resistance change rate VR (100 V) / VR (250 V) is too large, there is a problem in that current leaks due to voltage fluctuation. Therefore, the volume electric resistivity change rate VR (100 V) / VR (250 V). ) Is 100 times or less, preferably 50 times or less. Note that the lower limit of the rate of change VR (100V) / VR (250V) of the volume resistivity is 8 or more, particularly 10 or more in terms of exhibiting the effect of imparting a self-static function to the belt.

Therefore, the image forming apparatus belt of the present invention preferably satisfies the following formulas (1 ′), (2 ′), and (3 ′).
Formula (1 ′): SR (100 V) / SR (500 V) × 2 ≦ VR (100 V) / VR (250 V)
Formula (2 ′): 1 ≦ SR (100 V) / SR (500 V) ≦ 10
Formula (3 ′): 10 ≦ VR (100 V) / VR (250 V) ≦ 50

The resistance region of the image forming apparatus belt of the present invention varies depending on the purpose of use, but the surface electrical resistivity 1 × 10 ⁶ to 1 × 10 ¹⁴ Ω and the volume electrical resistivity 1 × 10 ⁶ to 1 × 10 ¹⁴ Ω.・ Selected from the cm range.

When the belt of the present invention is used as an intermediate transfer belt, the surface electrical resistivity 1 × 10 ⁶ to 1 × 10 ¹³ Ω and the volume electrical resistivity 1 × 10 ⁶ to 1 × 10 ¹³ Ω can be easily charged and transferred. · cm is preferred, and charged easily high voltage hardly damaged ^{1 × 10 10 ~1 × 10 14} Ω or a volume electrical resistivity of ^{1 × 10 10 ~1 × 10 14} Ω · cm in the case of using as a carrier transfer belt High regions are preferred.

  Further, it is preferable that the distribution of the surface electrical resistivity in one endless belt is narrow, and in each preferable surface electrical resistivity region, the difference between the maximum value and the minimum value in one belt is within two digits (maximum The value is preferably 100 times or less of the minimum value).

  The surface electrical resistivity and volume electrical resistivity of the endless belt should be easily measured by, for example, “HIRESTA”, “Loresta” manufactured by Dia Instruments Co., Ltd., or “R8340A” manufactured by ADVANTEST Co., Ltd. Can do.

[Tensile modulus]
The endless belt of the present invention preferably has a tensile elastic modulus of 300 MPa to 2500 MPa. If the tensile elastic modulus of the endless belt is low, for example, when it is used in an image forming apparatus as an intermediate transfer belt, a slight elongation may occur due to the tension, which may cause problems such as color misregistration. If it is too high, a motor load will be applied when driving the belt, so it will be necessary to reduce the thickness setting.If dust gets in between the roller and the belt, or if scratches due to friction with the photosensitive member enter, cracks will occur. Since it is easy to enter and there is a problem in reliability, it is not preferable. Further, in order to improve the transfer efficiency of the toner in the primary transfer, it is necessary to have a tensile elastic modulus that does not allow the belt to stretch and a tensile elastic modulus that does not cause the endless belt to become hard. Therefore, a preferable range of tensile elastic modulus is 300 MPa to 2500 MPa, particularly 500 MPa to 2000 MPa, and particularly preferable is 600 MPa to 1800 MPa.

  The tensile elastic modulus of the endless belt is adjusted from the viewpoint of improving the toner transfer efficiency. As described above, the toner transfer efficiency is improved by the chemical characteristics (contact angle with water) of the belt surface, and the toner transfer by the electrical characteristics. The most appropriate range may be determined in relation to the efficiency improvement effect.

[Contact angle with water]
The contact angle between the outer surface of the endless belt of the present invention and water is preferably 60 ° or more and less than 90 °. When the contact angle of the outer surface with water is less than 60 °, the toner adheres to the belt surface and forms a film, which deteriorates the toner secondary transfer efficiency. At 90 °, the toner transfer efficiency is deteriorated in the primary transfer. Therefore, the contact angle between the outer surface of the endless belt of the present invention and water is preferably 60 ° or more and less than 90 °, and particularly preferably 65 ° or more and 85 ° or less.

[Surface roughness Ra]
The surface roughness Ra of the endless belt of the present invention is preferably 0.05 μm or more and 0.3 μm or less. When the surface roughness Ra is less than 0.05 μm, the toner primary transfer efficiency is deteriorated. On the other hand, if it exceeds 0.3 μm, the secondary transfer efficiency of the toner deteriorates. Therefore, the surface roughness Ra of the endless belt of the present invention is preferably 0.05 μm or more and 0.3 μm or less, particularly 0.07 μm or more and 0.2 μm or less.

[Fold resistance]
When the endless belt of the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, an endless belt having good bending resistance is preferred because cracks occur and images cannot be obtained if the bending resistance is poor.

  The degree of bending resistance can be quantitatively evaluated by following the method for measuring the folding endurance of JIS P-8115, and it is judged that an endless belt with a higher folding endurance is less susceptible to cracking and has superior bending resistance. be able to.

  As a specific numerical value, if it exceeds 5000 times, it can be used with an excellent function as an endless belt for the life of the apparatus, but practically it is preferably 8000 times or more and preferably 10,000 times or more. More preferably.

  According to the present invention, depending on the amount of the thermoplastic elastomer added or alloying with the thermoplastic resin, a folding endurance of 50,000 times or more, further 100,000 or more can be obtained. Sufficient crack resistance can be obtained without performing secondary processing such as a crack prevention reinforcing tape ordinarily used for preventing the cracking.

[Shrinkage factor]
As the shrinkage rate characteristics of the endless belt of the present invention, the shrinkage rate with respect to a temperature of 60 ° C. and a humidity of 90% and a temperature after leaving for 24 hours of 23 ° C. and a humidity of 50% is preferably 0.2% or less. If the shrinkage rate is larger than these condition ranges, it is not preferable because the dimensional change becomes large during transportation and storage of the endless belt and it becomes impossible to use it, and electrical characteristics and mechanical characteristics may also change. More preferred shrinkage characteristics are 0.1% or less, and particularly preferred is 0.05% or less.

[Endless belt thickness]
If the thickness of the endless belt is excessively large, if the curvature with the roller is large, the deformation difference between the outer side and the inner side of the belt is large and the endless belt is easily broken. Further, the toner transferred to the outer side is deformed and scattered, and the image is deformed. On the other hand, if the thickness of the endless belt is excessively small, cracks are likely to occur due to slight scratches between the roller and the belt, or scratches due to contact with the photoreceptor, and the belt is likely to break. Therefore, the thickness of the endless belt of the present invention is preferably 70 to 300 μm, and particularly preferably 100 to 200 μm.

[IV] Alloy dispersion form and conductive substance dispersion form of endless belt In general, when two materials are melted and mixed, they are completely mixed (sometimes referred to as complete compatibilization), and not completely mixed, but an island-island structure There is a case to take.

  In the latter case, in general, when there is a large difference in volume fraction between the two materials, the larger volume fraction is the sea and the smaller volume fraction is more likely to have an island structure, and the difference in volume fraction is small. The difference in melt viscosity affects the sea-island structure, and it is said that the smaller the melt viscosity is, the easier it is to the sea, and the larger is the island.

  In the present invention, the alloy structure is different from the sea-island structure in the vicinity of the inner layer (the inner layer in the thickness direction of the endless belt) and the sea-island structure in the vicinity of the middle layer (the intermediate layer between the surface layer and the inner layer in the thickness direction of the endless belt). Alternatively, the same structure may be used, and materials may be mixed with each other to form island dispersion of 100 nm or less.

  What is important in the present invention is that the dispersed state of the conductive material in the middle layer and the dispersed state of the conductive material in the outer layer (surface layer in the thickness direction of the endless belt) are formed in almost the same form regardless of the sea-island structure. It is important that no matter how much the material is adjusted to the sea-island structure, depending on the molding process conditions, the orientation of the molten resin, the stress applied to the molten resin (shear stress, shear rate), or shear The shape of the sea and islands of the sea-island structure changes arbitrarily depending on the history, orientation in the process of cooling the molten resin, shear stress, shear rate, etc., and conductive filler such as carbon black as a conductive substance In the blended material, the state of dispersion of the conductive substance in the thickness direction of the endless belt changes depending on the shearing force and orientation. It is important to control the.

  That is, the inventors' research has revealed that the endless belt prepared so that the dispersed state of the conductive material in the vicinity of the outer layer of the endless belt and in the vicinity of the middle layer is the same has little voltage dependency of the surface electrical resistivity. . This indicates that it is important to be moderately uniform from the viewpoint of such a conductive material dispersion state, although the orientations in the inner and outer layers are different.

  In addition, depending on the general melt mixing and heating extrusion conditions, the dispersed particle size of the island portion of the sea island is only about 50 μm to 100 nm, but depending on the heating mixing conditions and extrusion conditions, the dispersed particle size is up to several nm or less. There is a possibility of miniaturization. In particular, those having a dispersed particle size of 100 nm or less have the effect of significantly improving the mechanical strength, the material also has a moderately improved melt viscosity, and the effect of uniformly dispersing the conductive material is exhibited. Therefore, it is particularly preferable.

  In addition, in the case of a structure in which two types of materials are alloyed or a structure in which fillers are added, the structure of the polymer material heated and melted may change during the cooling process. For example, in the presence of a filler or the like, the material that should be crystallized may not be crystallized and may remain in an amorphous state in the presence of a filler. Care must be taken because it may cause excessive shrinkage and mechanical strength may decrease extremely.

  In order to prevent such a state, it is preferable to take a structure in which a crystallized material is crystallized as a molded member among the components to be alloyed. That is, it is preferable to perform heat treatment, but from the viewpoint of cost, it is preferable to install a cooling means at the time of molding so as to sufficiently crystallize during continuous production.

In the present invention, the method for confirming the island shape of the sea-island structure is not particularly limited, and an endless belt is cut in a predetermined direction to create an ultrathin section, and about 2 with a dye such as ruthenium tetroxide (RuO ₄ ). A publicly known method such as staining with TEM (transmission electron microscope) or SEM (scanning electron microscope) can be used.

  Note that this observation requires special attention because the shape of the sea-island structure changes depending on the cutting direction of the thickness cross section of the endless belt, and the section cut in the circumferential direction and the section cut in the width direction of the endless belt are outside. Observe the shape of the sea island around 0-5 μm, around the center of thickness ± 5 μm, and inside 0-5 μm.

[V] Application of image forming apparatus belt The application of the image forming apparatus belt of the present invention is not particularly limited. However, in the field of OA equipment having particularly strict physical properties such as dimensional accuracy, bending resistance, and tensile elastic modulus, particularly for functional members Can be preferably used. When this endless belt is formed in a seamless belt shape, there are few problems such as cracking and elongation, which is preferable.

  The belt for an image forming apparatus of the present invention can be suitably used as an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, or a facsimile machine, particularly as an intermediate transfer belt, a transfer transfer belt, or a photoreceptor belt.

  The endless 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 reinforcing the end face, a reinforcing tape such as a heat-resistant tape may be bonded to the outside and / or inside of the endless belt along the side edge as necessary. As the reinforcing tape, a biaxially stretched polyester tape is preferable from the viewpoint of cost and strength, and the tape width is preferably 4 mm or more and 20 mm or less because the apparatus layout is compact. The thickness of the reinforcing tape is preferably 20 μm or more and 200 μm or less from the viewpoint of being able to drive the endless belt with low tension and preventing the occurrence of cracking.

  For the purpose of preventing meandering of the endless belt, a rubber sheet (meandering preventing guide) such as urethane rubber or silicone rubber may be bonded to the side edge of the endless belt with an adhesive. In this case, the preferable sheet width of the rubber sheet to be used is 2 to 10 mm, and 3 to 8 mm is particularly preferable in view of the layout of the apparatus and adhesive strength. Further, from the viewpoint of preventing meandering, the thickness of the meander-preventing rubber is preferably 0.5 to 3 mm, and more preferably 0.7 to 2 mm from the viewpoint of simplicity of the meandering prevention and meandering preventing effect.

  Furthermore, in combination with the above-mentioned reinforcing tape, it is preferable that the reinforcing tape is bonded to the endless belt and then the meandering prevention guide is bonded to the belt because of the effect of preventing the occurrence of belt cracking and the belt meandering.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

[material]
The following materials were used, and the blending ratios were as shown in Tables 1-3. In Tables 1 to 3, PEER represents a polyester-polyester copolymer elastomer, and PBT represents polybutylene terephthalate.
In the compounding ratio in Tables 1 to 3, the total of the thermoplastic elastomer and the thermoplastic resin is 100 parts by weight.
The ratios of the thermoplastic elastomer and the thermoplastic resin are shown in Tables 1 to 3 with the total amount of both being 100% by weight and the ratio of each being weight%.

Thermoplastic elastomer 1 (Examples 1 to 7, Comparative Example 1):
Polyester-polyester elastomer "Perprene S3001" manufactured by Toyobo Co., Ltd.
MFR (240 ° C., 2.16 kgf load): 21 g / 10 min, crystal melting point 216 ° C.
Thermoplastic elastomer 2 (Example 8):
Polyester-polyester elastomer “Perprene S2001” manufactured by Toyobo Co., Ltd.
MFR (240 ° C., 2.16 kgf load): 21 g / 10 min, crystal melting point 206 ° C.
Thermoplastic elastomer 3 (Example 9):
Polyester-polyester elastomer “Perprene S1001” manufactured by Toyobo Co., Ltd.
MFR (240 ° C., 2.16 kgf load): 21 g / 10 minutes, crystal melting point 200 ° C.
Thermoplastic elastomer 4 (Example 10):
Polyester-polyester elastomer "Perprene S6001" manufactured by Toyobo Co., Ltd.
MFR (240 ° C., 2.16 kgf load): 15 g / 10 min, crystal melting point 218 ° C.
Thermoplastic elastomer 5 (Comparative Examples 2 to 4):
Polyester-ether elastomer “Perprene P150B” manufactured by Toyobo Co., Ltd.
MFR (240 ° C., 2.16 kgf load): 19 g / 10 min, crystal melting point 212 ° C.
-PBT (Examples 2 to 4):
“128” manufactured by Kanebo Synthetic Fibers
Weight average molecular weight = 40,000
PS-converted weight average molecular weight = 122,000
MFR (240 ° C., 2.16 kgf load): 7 g / 10 minutes PBT (Examples 5 to 10, Comparative Example 1):
“Novaduran 5040ZS” manufactured by Mitsubishi Engineering Plastics Co., Ltd.
Weight average molecular weight = 40,000
PS-converted weight average molecular weight = 122,000
MFR (240 ° C., 2.16 kgf load): 4 g / 10 minutes PBT (Comparative Examples 2 to 4):
“Novaduran 5010” manufactured by Mitsubishi Engineering Plastics Co., Ltd.
MFR (240 ° C., 2.16 kgf load): 16 g / 10 min Polymerization catalyst: Titanium (IV) butoxide / magnesium acetate Chelator: Phosphorylation antioxidant “PEPQ” manufactured by Clariant Japan
・ Carbon black: Denka Black manufactured by Electrochemical Co., Ltd.
DBP oil absorption = 180ml / 100g
Specific surface area = 65 m ² / g
Volatile content = 0%
Average primary particle size = 39 nm
・ Thickener 1: Glycidyl methacrylate-containing polymer “MODIPA A” manufactured by NOF Corporation
4400 "
MI value (190 ° C., 2.16 kgf load) according to JIS K7210
3g / 10min

[Heat kneading]
Each raw material was pelletized using a twin-screw kneading extruder (“PMT32” manufactured by IKG Corporation). Conditions were as shown in Tables 1-3.

[Endless belt molding method]
This material pellet was dried, and the annular die was formed by an extruder of 40 mmφ with a six-spiral annular die having a diameter of 160 mm and a die slip width of 1.5 mm (having 16 temperature control mechanisms in the circumferential direction of the annular die). While extruding in the molten tube state downward, the extruded molten tube is in contact with the outer surface (temperature 80 ° C.) of a cooling mandrel having an outer diameter of 153 mm mounted on the same axis as the annular die via a support rod, and is cooled and solidified. Next, a length of 340 mm is taken while the seamless belt is being held in a cylindrical shape by a cylindrical core installed in the seamless belt and a four-point belt type take-up machine installed on the outside. And adjust the extrusion amount, take-up speed, and extrusion temperature so that the thickness becomes 140 μm and the surface electrical resistivity becomes 1 × 10 ¹⁰ to 1 × 10 ¹² Ω. The resin seamless belt having an inner diameter of 151 mm was prepared. The molding conditions were as shown in Table 1 or Table 3.

In addition, for the molding material, a sample was taken for 5 to 1/6 minutes after the start of heating with a melt indexer “T-01” (240 ° C., 2.16 kgf load) manufactured by Toyo Seiki Co., Ltd., and the weight was measured. (M) The MFR obtained by the following formula is as shown in Tables 1-3.
Formula: MFR = (600 × m) / t (g / 10 min)
t = sampling time (seconds) (here 60 seconds)
m = weight of sampling (g)

[Evaluation]
The evaluation was carried out by opening the endless belt to a required size as required, and the results are shown in Tables 1 to 3.

-Tensile elastic modulus Based on ISO R1184-1970, the test piece was cut into a width of 15 mm and a length of 150 mm, and measured with a tensile speed of 1 mm / min and a distance between grips of 100 mm.

-Shrinkage rate After cutting the endless belt into pieces with a constant width of 200 mm, further cut one place in the width direction. Next, the obtained sample was left to stand at a temperature of 23 ° C. and a humidity of 50% for 24 hours, and then the circumferential length of the endless belt was measured using a three-dimensional dimension measuring instrument (“GJ800A” manufactured by Tokyo Seimitsu Co., Ltd. equipped with a Nikon microscope). )). This measured value is defined as (P).
Next, after leaving the above sample for 24 hours in a constant temperature and humidity chamber set to a temperature of 60 ° C. and a humidity of 90%, the sample was left to stand for 24 hours at a temperature of 23 ° C. and a humidity of 50%. The length in the circumferential direction was measured using a three-dimensional dimension measuring instrument. Let this measured value be (Q). As the shrinkage rate of the sample after being left in each temperature and humidity condition with respect to a temperature of 23 ° C. and a humidity of 50%, a numerical value obtained from the following equation was used.
Shrinkage rate = {(P) − (Q)} / (P) × 100

-Circumference difference After cutting the endless belt into a constant width of 200 mm, further cut one place in the width direction. Next, the sample obtained was allowed to stand for 24 hours at a temperature of 23 ° C. and a humidity of 50%, and then the circumferential length of both ends of the endless belt was measured with a three-dimensional dimension measuring instrument (Tokyo Seimitsu with a Nikon microscope attached). ("GJ800A" manufactured by the company). A difference in circumferential length between both ends is defined as a circumferential length difference.

・ Bending resistance (number of foldings)
In accordance with JIS P-8115, the test piece was cut into a size of 15 mm in width and 100 mm in length, and was subjected to a bending speed of 175 times / minute, a rotation angle of 135 ° left and right, and a tensile load of 1.0 kgf with an MIT tester. Then, the number of bendings to breakage was measured with the radius of curvature of the tip of the bending jig being R = 0.38 mm.

-Surface electrical resistivity A product name "Hiresta (UR terminal)" manufactured by Dia Instruments Co., Ltd. was used, and the belt circumferential direction was measured at a pitch of 20 mm under conditions of 100 V, 500 V, and 10 seconds each.

-Volume resistivity The product name "Hiresta (UR terminal)" manufactured by Dia Instruments Co., Ltd. was used, and the belt circumferential direction was measured at a pitch of 20 mm under conditions of 100 V, 250 V, and 10 seconds each.

・ Electric resistance environmental fluctuation rate In each of the surface electrical resistivity and volume electrical resistivity, the electrical resistivity after leaving for 20 hours at a temperature of 10 ° C. and a humidity of 20% (LL condition), and left for 20 hours at a temperature of 30 ° C. and a humidity of 80% The ratio (electric resistivity (LL condition) / electric resistivity (HH condition)) with the subsequent electrical resistivity (HH condition) was determined and used as the electrical resistance environment fluctuation rate.

・ Roller scratch resistance As shown in FIG. 3A, a sample 31 having a width of 15 mm and a length of 44 mm is wound around the outer circumference of a roller 30 having a diameter of 14 mm, and both ends are fixed with tape, and the temperature is 60 ° C. and the humidity is 90%. For 2 hours, and further for 24 hours in an environment of temperature 23 ° C. and humidity 50%, after which the sample 31 is removed from the roller 30 and a sample with a flaw as shown in FIG. A distance L (mm) between both short sides of 31 was measured, and a roller wrinkle restoration rate was calculated by the following formula to obtain roller wrinkle resistance.
Roller wrinkle restoration rate = L / 44 x 100

-Contact angle with water A drop of water was dropped on the outer surface of the endless belt, and the contact angle of water after 1 minute was measured using an Elmer goniometer "G-1."

・ Surface roughness Cut the outer surface of the endless belt into a sample of about 50 mm × 50 mm, and using a key depth ultra-fine shape measurement microscope product name “VK8500” manufactured by Keyence Corporation, lens 100 times, pitch 0.01 μm, shutter speed AUTO, The surface roughness of an area of 40 μm × 40 μm was measured at four points under the measurement condition of gain 835, and the average value was taken as the measured value of the surface roughness (Ra). Similarly, the maximum height (Ry) and ten-point average roughness (Rz) were determined.

Image Evaluation As shown in FIG. 1, a polyester tape of 50 μm and a width of 10 mm is attached to both outer ends of the endless belt 20 as an inner reinforcing tape 22 and an outer reinforcing tape 21, and a polyurethane thickness of 1 is attached to both inner ends. An endless belt with a meandering prevention rubber 23 with a width of 0.0 mm and a width of 5 mm is mounted on a color laser printer model name “LP3000C” manufactured by Seiko Epson Corporation, and is placed under an environment of 60 ° C. and 90% humidity. After standing for a period of time, a color print test was performed in an environment of a temperature of 23 ° C. and a humidity of 50%.

[Examples 1 to 4]
As shown in Table 1, polyester-polyester elastomer “Perprene S3001” manufactured by Toyobo Co., Ltd. was used as the thermoplastic elastomer, and bell-spun synthetic fiber “128” was used as the thermoplastic resin. ) This thermoplastic elastomer, a thermoplastic resin and a chelator, a thickener and a carbon black formulation were heated and kneaded to obtain material pellets. The heating and kneading conditions at this time are as shown in Table 1. The resin temperature and the residence time in the kneader were adjusted, the reaction in the kneader was suppressed, and the kneading conditions were adjusted so that the electrical resistance became a semiconductive region. . This material pellet was extruded to produce an endless belt.
All of the endless belts were excellent in roller tack resistance.

Each endless belt has a surface electrical resistivity of SR (100 V) average value of 1 × 10 ¹¹ Ω / □ to 7 × 10 ¹¹ Ω / □, and a volume electric resistivity of VR (100 V) average value of 8 × 10. ¹⁰ Ω · cm to 9 × 10 ¹² Ω · cm, and the voltage dependency SR (100 V) / SR (500 V) of the surface electrical resistivity of 100 V to 500 V is 2.7 to 6.7, one order (10 Voltage dependence VR (100V) / VR (250V) of volume electrical resistivity of 100V to 250V is 10 to 23.1 and within 2 orders (100 times), good non-voltage dependence Sex was obtained.

  When these belts are mounted on an image forming apparatus as an intermediate transfer belt as shown in FIG. 1, a good image with few missing characters in both primary transfer and secondary transfer can be obtained.

  Further, even when 200,000 images were output in this state, no crack was generated, and the resistance value varied little under the HH condition / LL condition, and the resistance variation was small. Further, the influence of the roller trace on the image was hardly observed.

[Examples 5 to 7]
Change the thermoplastic resin to PBT containing a polymerization catalyst ("Novaduran 5040ZS" manufactured by Mitsubishi Engineering Plastics Co., Ltd.) and adjust the blending ratio of the thermoplastic resin and the thermoplastic elastomer and the blending amount of the thickener ( In Examples 5 and 6, an endless belt was obtained in the same manner as in Example 4 except that the polymerization catalyst was blended together with no thickener added. Even in Examples 5 to 7, an endless belt having excellent resistance to roller wrinkles was obtained. However, as the ratios of Examples 5 and 6 and the thermoplastic resin increased, the number of folding resistances decreased and the resistance to roller wrinkles decreased. It turned out that there is a tendency for sex to fall.
When this endless belt was mounted on an image forming apparatus, a good image could be obtained.

[Examples 8 to 10]
An endless belt was obtained in the same manner as in Example 7 except that the type of the thermoplastic elastomer was changed. Even in Examples 8 to 10, an endless belt having excellent appearance and excellent roller tackiness was obtained, but it was found that the roller tackiness tends to deteriorate as the melting point of the thermoplastic elastomer increases. It was.
When this endless belt was mounted on an image forming apparatus, a good image could be obtained.

[Comparative Example 1]
An endless belt was obtained in the same manner as in Example 5, except that the thermoplastic elastomer (polyester-polyester elastomer “Perprene S3001” manufactured by Toyobo Co., Ltd.) was reduced to 5%. It was.

  In Comparative Example 1, the surface roughness was good, but the roller wrinkle resistance was poor and a good image could not be obtained for a long time.

[Comparative Examples 2 to 4]
Polyester polyether type using aromatic polyester for hard segment and aliphatic polyether for soft segment as thermoplastic elastomer, and “NOVADURAN 5010” manufactured by Mitsubishi Engineering Plastics Co., Ltd. as thermoplastic resin. An endless belt was obtained in the same manner as in Example 5 except that the blending ratio of the elastomer and the thermoplastic resin was changed and the polymerization catalyst was not added.

In each of the comparative examples, it was found that the roller tackiness was poor, and the type of thermoplastic elastomer affected the roller tackiness.
Moreover, the voltage dependence of each of surface electrical resistivity and volume electrical resistivity was larger than Examples 1-10 and Comparative Example 1.

  In addition, the applied voltage dependence of the surface electrical resistivity in each Example and the comparative example is shown in FIG. 4, and the applied voltage dependence of the volume electrical resistivity is shown in FIG. In addition, FIG. 6 shows the resistance to roller wrinkles (roller wrinkle restoration rate).

  As is clear from Tables 1 to 3 and FIGS. 4 to 6, according to this example, the roller resistance is excellent, the voltage dependency of the electrical resistivity is small, and the fluctuation of the electrical resistivity due to the temperature and humidity environment is small. , Images with excellent bending resistance, chemical resistance and molding dimensional stability, and high image quality on all types of paper, from uneven paper to smooth paper, in any environment of low temperature and low humidity to high temperature and high humidity An endless belt for a forming apparatus is provided.

It is a perspective view which shows the intermediate transfer belt for evaluation in an Example and a comparative example. It is a side view of a conventional intermediate transfer device. It is a perspective view which shows the evaluation method of a roller wrinkle resistance. It is a graph which shows the applied voltage dependence of the surface electrical resistivity in an Example and a comparative example. It is a graph which shows the applied voltage dependence of the volume electrical resistivity in an Example and a comparative example. It is a graph which shows the roller wrinkle resistance (roller wrinkle restoration rate) in an Example and a comparative example.

Explanation of symbols

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 20 Endless belt 21 Outer reinforcement tape 22 Inner reinforcement tape 23 Meander prevention guide rubber 30 Roller 31 Sample

Claims (19)

An endless belt used in an image forming apparatus, wherein the belt is formed by molding a blend of a thermoplastic polymer component including a thermoplastic elastomer and a conductive material.
The thermoplastic elastomer is a polyester polyester block copolymer in which the hard segment is an aromatic polyester and the soft segment is an aliphatic polyester.
The thermoplastic polymer component contains 10% by weight or more of the thermoplastic elastomer,
The blend is formed by blending 1 to 20 parts by weight of a conductive substance with respect to 100 parts by weight of the thermoplastic polymer component.
The surface electrical resistivity measured at a voltage of 100 V is in the range of 1 × 10 ⁶ to 1 × 10 ¹⁴ Ω / □ and the volume resistivity is in the range of 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm,
A belt for an image forming apparatus, wherein variations in electrical resistivity satisfy a maximum value / minimum value ≦ 100.   2. The thermoplastic elastomer according to claim 1, having a crystalline melting point of 190 ° C. or higher and 220 ° C. or lower, and a melt flow rate (MFR) according to JIS K7210 (240 ° C., 2.16 kgf load) of 10 g / 10 min or more and 18 g / 10. A belt for an image forming apparatus, characterized by being less than or equal to minutes. In claim 1 or 2,
SR (100 V) is the surface electrical resistivity measured at an applied voltage of 100 V for 10 seconds.
SR (500V), the surface electrical resistivity measured at an applied voltage of 500V for 10 seconds,
The volume resistivity when measured at an applied voltage of 100 V for 10 seconds is VR (100 V),
The volume resistivity when measured at an applied voltage of 250 V for 10 seconds is VR (250 V),
A belt for an image forming apparatus that satisfies the following expressions (1), (2), and (3):
Formula (1): SR (100 V) / SR (500 V) <VR (100 V) / VR (250 V)
Formula (2): SR (100 V) / SR (500 V) ≦ 30
Formula (3): 8 ≦ VR (100 V) / VR (250 V) ≦ 100   The surface roughness Ra according to any one of claims 1 to 3, wherein the tensile elastic modulus of the endless belt is 300 MPa or more and 2500 MPa or less, the contact angle of the outer surface of the endless belt with water is 60 ° or more and less than 90 °. Is a belt for an image forming apparatus, wherein the belt is 0.05 μm or more and 0.3 μm or less.   The thermoplastic polymer component according to any one of claims 1 to 4, further comprising a thermoplastic resin, wherein a weight ratio of the thermoplastic elastomer to the thermoplastic resin is thermoplastic elastomer / thermoplastic resin = 10 / A belt for an image forming apparatus, wherein the belt is 90 to 90/10.   6. The belt for an image forming apparatus according to claim 5, wherein a weight ratio of the thermoplastic elastomer to the thermoplastic resin is thermoplastic elastomer / thermoplastic resin = 20/80 to 80/20.   7. The belt for an image forming apparatus according to claim 5, wherein the thermoplastic resin contains polyalkylene terephthalate as a main component.   8. The belt for an image forming apparatus according to claim 7, wherein the polyalkylene terephthalate is polybutylene terephthalate.   9. The belt for an image forming apparatus according to claim 7, wherein the polyalkylene terephthalate contains a polymerization catalyst.   10. The composition according to claim 1, wherein the blend further has a melt flow rate (MFR) according to JIS K7210 (190 ° C., 2.16 kgf load) of 0.01 g / 10 min or more and 10 g / 10 min or less. A belt for an image forming apparatus, comprising a thickener comprising a polymer having a value of 0.01 to 20 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component.   11. The belt for an image forming apparatus according to claim 10, wherein the thickener is a polymer containing an epoxy group or a glycidyl methacrylate group. In any one of claims 1 to 11, as a conductive material, DBP oil absorption of 50 cm ^3/100 g or more 300 cm ^3/100 g or less and a specific surface area of ^35m 2 / g or more 500 meters ² / g or less, a volatile content of 0% or more and 20 %, And carbon black having an average primary particle size of 20 nm or more and 50 nm or less is blended so as to satisfy the following formulas (i) and (ii).
Formula (i): LogY ≧ −X + 20
Formula (ii): LogY ≦ −X + 30
However, X and Y are as follows.
X: Carbon black content (% by weight) in the endless belt
Y: Surface electrical resistivity (Ω) at 100 V applied voltage, 10 seconds for endless belt   The molding material according to any one of claims 1 to 12, wherein a molding viscosity represented by a melt flow rate (MFR) according to JIS K7210 (240 ° C, 2.16 kgf load) is 1 g / 10 min or more and 10 g / 10 min or less. A belt for an image forming apparatus, which is formed by extrusion molding.   14. The belt for an image forming apparatus according to any one of claims 1 to 13, wherein the belt is formed by pulling a molten tube heated and extruded from an annular die while cooling or cooling and solidifying the molten tube.   15. The image forming apparatus belt according to claim 14, wherein a plurality of temperature adjusting mechanisms are provided in a circumferential direction of the annular die.   16. The belt for an image forming apparatus according to claim 14, wherein the melting tube is cooled by bringing a mold whose temperature is adjusted in a range of 30 to 150 ° C. into contact with the inside or outside of the melting tube.   17. The belt for an image forming apparatus according to claim 14, wherein the melting tube is pulled out while maintaining a cylindrical shape.   18. The image forming apparatus belt according to claim 1, wherein the image forming apparatus belt is a seamless intermediate transfer belt, a conveyance transfer belt, a transfer fixing belt, a fixing belt, a photosensitive belt, or a development sleep. An image forming apparatus comprising the belt for an image forming apparatus according to claim 1.

Images