JP2007328279A - Image forming apparatus and endless belt therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt for image forming apparatus that has good mechanical characteristics such as bending resistance and surface characteristics, and has superior toner transferability and cleanability compatible with high-resolution; and to provide an image forming apparatus including the endless belt for the image forming apparatus. <P>SOLUTION: The endless belt for the image forming apparatus contains a thermoplastic polymer component consisting of a thermoplastic elastomer and/or thermoplastic resin as the main component. The endless belt contains an antioxidant and fine particle of fluororesin applied with heat treatment. The content of the fluororesin fine particle is 0.1-20 pts.wt. per 100 pts.wt. of the thermoplastic polymer component. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an endless belt (endless belt) for an image forming apparatus, which has excellent mechanical properties such as bending resistance and surface characteristics, and excellent toner transferability and toner cleaning properties, and an image forming apparatus for the image forming apparatus. The present invention relates to an image forming apparatus including an endless belt.

  Conventionally, as an image forming apparatus such as an OA device, an electrophotographic system using a photoconductor and toner, and an image forming apparatus using gel-like ink instead of toner have been devised and put on the market. These devices include conductive belts, intermediate transfer belts, paper transfer belts, transfer separation belts, charging tubes, developing sleeves, fixing belts, toner transfer belts, etc. Endless belts controlled to have various insulating electric resistances are used.

  For example, an intermediate transfer device used in an electrophotographic system is configured to once form a toner image on an intermediate transfer member and then transfer the toner to paper or the like. An endless belt made of a seamless belt is used for charging and discharging the toner on the surface layer of the intermediate transfer member. The seamless belt is set to have different surface electric resistance and 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.

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

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

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

  By the way, in the case of a conductive endless belt used in an image forming apparatus such as an electrophotographic copying machine or a printer, since it is functionally driven with a high tension and a high voltage for a long time by two or more rolls, 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 at differentiating from the inkjet system by a high-speed printing technique, and is an image forming apparatus that prints at a high speed by a tandem type paper conveyance transfer in which four photoconductors are arranged and an intermediate transfer system. Has been commercialized. For this reason, further improvement in durability and prevention of image misalignment have become increasingly important for endless belts for image forming apparatuses.

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

  For this reason, 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 improvements to surface properties, chemical properties, and electrical properties of transfer belts have been made. The demand 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. For example, the surface of an endless belt is required to be smoother in order to improve the cleaning properties for toners having a smaller particle size in recent years. However, if the surface of the endless belt is too smooth, a blade that scrapes off residual toner. The friction of the toner increases, and troubles related to the toner cleaning property are likely to occur.

From the above, the following conditions <1> to <8> are required for the endless belt for an image forming apparatus such as a transfer belt in recent years.
<1> Has predetermined surface electrical resistivity and volume electrical resistivity in the semiconductor region, has little resistance variation, and has excellent toner releasability
<2> Moderately smooth surface and excellent toner cleaning properties
<3> Thin and uniform
<4> Strong mechanical strength (hard to stretch and hard to crack)
<5> Fluctuations in resistance, dimensions, and mechanical strength due to the environment (temperature and humidity) are small.
<6> Low cost
<7> A seamless and perfect circle (small difference in circumference in the belt width direction) belt
<8> High-quality prints on various paper types

  Conventionally, in order to improve the releasability of the toner transferred onto the transfer belt, a fluororesin is added to the base polymer such as a thermoplastic resin or a thermosetting resin to reduce the surface energy of the transfer belt. It has been proposed.

For example, Patent Document 1 proposes blending a fluororesin having a melting point of 250 ° C. or lower with a thermoplastic resin such as a polyamide resin. Patent Document 2 proposes blending a fluororesin with a polyimide resin. Patent Document 3 proposes that a substance that reduces wettability, such as a fluororesin, is blended with a resin such as polycarbonate. Patent Document 4 includes, as a comparative example, a mixture of PPS (polyphenylene sulfide) and PTFE (polytetrafluoroethylene) fine particles.
However, no proposal has been made to blend heat-treated fluororesin fine particles.

  In addition, since the belt for image forming apparatuses, such as a transfer belt, is exposed to high temperature in the manufacturing process (at the time of heat kneading and extrusion molding) and the use environment, it is usually essential to contain an antioxidant. In other words, belts that do not contain antioxidants have the problem that mechanical properties such as bending resistance are easily lost due to oxidative deterioration during heating and kneading and extrusion, and cracks are likely to occur. However, deterioration over time is remarkable, and practically satisfactory performance cannot be obtained in terms of durability.

On the other hand, as an inexpensive belt manufacturing method, a transfer belt manufacturing method using an extrusion molding method in which an annular die is attached to the tip of an extruder has been proposed.
JP 2005-164900 A JP 2004-157221 A Japanese Patent Laid-Open No. 2-198476 Japanese Patent Laid-Open No. 2005-316040

However, when a molding material in which a toner releasability-imparting component having a low surface energy such as a fluororesin is added to a thermoplastic resin or thermoplastic elastomer is extruded, the compatibility of the material is poor and the resulting mixture does not mix. There was a problem of adversely affecting mechanical properties such as flex resistance. In particular, PTFE generally has a large molecular weight and a high melting point, so it does not mix well with the thermoplastic polymer component, and PTFE is stretched and fibrillated by the shearing force during heating and kneading, which causes melting of the molding material. There is a problem in that the viscosity increases and melt extrusion becomes difficult, and the appearance of the resulting belt deteriorates.
In addition, the conventional endless belt containing a fluorine resin has a problem that the effect of improving the toner cleaning property is not sufficient.

  The present invention solves the above-mentioned conventional problems, an endless belt for an image forming apparatus capable of high image quality, having excellent mechanical properties such as bending resistance and surface properties, excellent toner transferability and toner cleaning properties, and An object of the present invention is to provide an image forming apparatus including an endless belt for an image forming apparatus.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors mixed heat-treated fluororesin fine particles at a predetermined ratio with a thermoplastic polymer component containing an antioxidant, It has been found that the above problems can be solved.

  For endless belts, when heat-kneading at the time of blending materials, or when an endless belt is obtained by an extrusion molding method in which the residence time of the molding material is relatively long, a thermoplastic polymer component with excellent heat resistance or addition In addition, it is necessary to pay close attention to the addition of additives such as antioxidants to prevent oxidation deterioration reaction in the kneader and oxidation deterioration reaction during heat extrusion molding.

As a result of investigating the mechanism of occurrence of poor toner cleaning performance of a conventional endless belt, the present inventors have found that this antioxidant bleeds to the surface of the endless belt, which causes cleaning failure.
That is, the antioxidant that bleeds out on the belt surface adheres to the cleaning blade by rubbing against the cleaning blade during toner cleaning, and the antioxidant accumulates on the edge of the blade, resulting in oxidation. In the blade portion where the inhibitor is deposited, the toner scraping effect is reduced, and cleaning failure (toner cleaning blade slipping phenomenon) occurs.
Conventionally used fluororesins could not prevent poor cleaning due to bleeding out of this antioxidant.

  In order to solve this problem, it is conceivable to reduce the blending amount of the antioxidant that causes cleaning failure. In this case, the thermoplastic polymer component due to heat applied to the material at the time of kneading or extrusion molding Oxidative degradation (thermal degradation) of the belt causes a problem that the mechanical characteristics of the endless belt are degraded. Even when the amount of the antioxidant is small, if the friction between the belt surface and the blade is large, the antioxidant slightly adhered to the belt surface is scraped off by the blade and adheres to the blade. Eventually, defective cleaning occurs. Therefore, it is necessary to solve the cleaning failure while blending the antioxidant.

Therefore, as a result of examining the type, particle shape, particle size, etc. of the fluororesin that makes it easy to reduce the coefficient of friction with the blade and makes it difficult for the antioxidant to adhere to the blade, the fluororesin fine particles subjected to heat treatment It has been found that by blending, it becomes difficult to cause poor cleaning due to the antioxidant.
That is, the gist of the present invention is as follows.

[1] An endless belt used in an image forming apparatus, the endless belt having a thermoplastic polymer component composed mainly of a thermoplastic elastomer and / or a thermoplastic resin as a main component, subjected to an antioxidant and heat treatment An endless belt for an image forming apparatus, wherein the content of the fluororesin fine particles is 0.1 to 20 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component.

[2] The endless belt for an image forming apparatus according to [1], wherein the heat treatment temperature of the fluororesin microparticles is 5 ° C. or more higher than the melting point of the fluororesin.

[3] The endless belt for an image forming apparatus according to [1] or [2], wherein the melting point of the fluororesin is 10 ° C. or more higher than the melting point of the thermoplastic polymer component.

[4] An endless belt for an image forming apparatus according to [1] to [3], wherein the fluororesin fine particles have an average particle size of 0.1 to 10 μm.

[5] The endless belt for an image forming apparatus according to [1] to [4], wherein a 5% weight loss temperature in thermogravimetric measurement of the fluororesin is 550 ° C. or less.

[6] The endless belt for an image forming apparatus according to [1] to [5], wherein the content of the antioxidant is 0.01 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component. .

[7] An endless belt for an image forming apparatus according to [1] to [6], wherein the content of the fluororesin fine particles is 1 to 100 times the weight of the antioxidant.

[8] In [1] to [7], the fluororesin fine particles and the antioxidant are mixed in advance, and the mixture is heated and kneaded with the thermoplastic polymer component to obtain a molding material, and the molding material is molded. An endless belt for an image forming apparatus.

[9] The endless belt for an image forming apparatus according to [8], wherein the molding tube is formed by pulling the molding tube heated and extruded from an annular die while cooling or solidifying the tube.

[10] The endless belt for an image forming apparatus according to [1] to [9], wherein the conductive component is contained in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component.

[11] An endless belt for an image forming apparatus according to [10], wherein the conductive material is carbon black.

[12] In [1] to [11], the thermoplastic polymer component is a ratio of thermoplastic elastomer / thermoplastic resin = 5/95 to 95/5 by weight ratio of thermoplastic elastomer and thermoplastic resin. An endless belt for an image forming apparatus.

[13] An endless belt for an image forming apparatus according to [1] to [12], wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.

[14] The endless belt for an image forming apparatus according to [1] to [13], wherein the thermoplastic resin contains polyalkylene terephthalate as a main component.

[15] An endless belt for an image forming apparatus according to [14], wherein the polyalkylene terephthalate is polybutylene terephthalate.

[16] The endless belt for an image forming apparatus according to [1] to [15], which is a seamless intermediate transfer belt, conveyance transfer belt, transfer fixing belt, fixing belt, photosensitive belt, or development sleep. .

[17] An image forming apparatus comprising the endless belt for an image forming apparatus according to any one of [1] to [16].

By blending the fluoropolymer fine particles heat-treated with the antioxidant at a predetermined ratio with respect to the thermoplastic polymer component,
(1) The friction coefficient between the blade and the endless belt is lowered, the force with which the antioxidant is pressed against the blade is weakened, and the antioxidant is prevented from adhering to the blade edge.
(2) The fluororesin fine particles bleed together with the antioxidant, thereby imparting releasability to the antioxidant itself and preventing the deposition of the antioxidant on the blade.
This reduces the adhesion between the antioxidant and the blade, and as a result, the chemicals have excellent toner transferability and cleanability without deteriorating the mechanical strength and without deteriorating the surface roughness. It is possible to provide an endless belt for an image forming apparatus capable of obtaining physical properties, having excellent mechanical properties such as bending resistance and surface characteristics, and excellent in toner transferability and toner cleaning properties and capable of high image quality. It becomes.

Although the details of the mechanism of the above effect by blending a predetermined amount of the heat-treated fluororesin fine particles are not clear, it is estimated as follows.
A fluororesin, such as PTFE, has a high melting point of 300 ° C. or higher and generally has a molecular weight of about 1,000,000 or higher. Therefore, the material has a very high melt viscosity and cannot be melt extruded.
When such a fluororesin is simply made into fine particles and blended with the thermoplastic polymer component as an additive, as described above, the fluororesin is stretched by the shearing force applied during kneading, and is likely to cause fibrillation, and is a film like an endless belt. When the film was formed into a shape, there was a problem that the surface was difficult to be smooth.

  However, if fluororesin fine particles that have been pulverized after heat treatment are used, the surface of the fluororesin becomes hard. This is because the particle diameter of the fluororesin fine particles tends to be uniform during pulverization, and during kneading and extrusion molding. Due to the effect that the fluororesin fine particles are easily dispersed in the matrix polymer while maintaining the particle shape without being fibrillated when subjected to shearing, the belt appearance is poor due to non-uniformity of the fluororesin fine particles and poor dispersion This is effective in improving the releasability of the antioxidant and can effectively prevent poor cleaning due to the antioxidant adhering to the blade. Moreover, the heat-treated fluororesin fine particles moderately increase the melt viscosity of the molding material, so that the dispersibility of conductive components such as carbon black with respect to the base polymer is improved, and the electric resistance value of the endless belt is easily made uniform. The effect is also achieved, and an endless belt compatible with high image quality is provided.

In the present invention, the heat treatment temperature of the fluororesin fine particles is preferably 5 ° C. or more higher than the melting point of the fluororesin (Claim 2), and the melting point of the fluororesin is higher than the melting point of the thermoplastic polymer component. Is preferably 10 ° C. or higher.
The average particle diameter of the fluororesin fine particles is preferably 0.1 to 10 μm, and the 5% weight loss temperature in thermogravimetry is preferably 550 ° C. or less (claims 4 and 5).

  Moreover, it is preferable that content of antioxidant is 0.01-5 weight part with respect to 100 weight part of this thermoplastic polymer component, and content of fluororesin fine particle is 1-100 of this antioxidant. It is preferable that it is weight times (Claims 6 and 7).

  The endless belt for an image forming apparatus of the present invention is obtained by previously mixing fluororesin fine particles and an antioxidant, heating and kneading the mixture with the thermoplastic polymer component to obtain a molding material, and molding the molding material. (Claim 8), and in particular, it is preferably formed by taking out the molding material while being cooled or solidified while being cooled or solidified by heating and extruding the molding material from an annular die (Claim 9).

  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 endless belt of the present invention preferably further contains 0.1 to 30 parts by weight of a conductive component, preferably carbon black, relative to 100 parts by weight of the thermoplastic polymer component (claims 10 and 11).

The endless belt for an image forming apparatus of the present invention includes a thermoplastic elastomer and a thermoplastic resin as a thermoplastic polymer component in a weight ratio of thermoplastic elastomer / thermoplastic resin = 5/95 to 95/5. Polyester terephthalate is preferable as the thermoplastic elastomer, and polyalkylene terephthalate, particularly polybutylene terephthalate, is preferable as the thermoplastic resin (claims 12 to 15).
With such an alloy material of thermoplastic elastomer and thermoplastic resin, it is possible to obtain good durability and appropriate elastic modulus, satisfy the preferred electrical characteristics of the present invention, and good extrudability Can be obtained.

  The endless 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.

  With the image forming apparatus of the present invention including such an endless belt for an image forming apparatus of the present invention, a high-quality image can be formed over a long period of time (claim 17).

  Hereinafter, embodiments of an endless belt for an image forming apparatus and an image forming apparatus according to the present invention will be described in detail.

(1) Endless belt material The endless belt of the present invention comprises a thermoplastic polymer component comprising a thermoplastic elastomer and / or a thermoplastic resin, an antioxidant and heat-treated fluororesin fine particles, and more preferably a conductive substance. It is composed of other additive components blended as necessary. The endless belt material according to the present invention only needs to contain a predetermined amount of an antioxidant and heat-treated fluororesin particles with respect to the thermoplastic polymer component, and there are no restrictions on the types of other materials. Absent.

<Thermoplastic polymer component>
(Thermoplastic resin)
Examples of the thermoplastic resin used in the endless belt of the present invention include polypropylene, propylene ethylene block or random copolymer, rubber or latex component such as ethylene / propylene copolymer rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymer. Polymer or hydrogenated derivatives thereof, polybutadiene, polyisobutylene, polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, liquid crystalline polyester, polysulfone, polyphenylene sulfide, polybisamidotriazole, acrylic, polyfluorinated vinylidene, polyfluorinated vinyl , Chlorotrifluoroethylene, acrylic acid alkyl ester copolymer, polyester ester copolymer, polyether ester copolymer, poly Teruamido copolymer, those composed of one or a mixture of two or more of these such as polyurethane copolymers can be used. Polyethylene (high density, medium density, low density, linear low density) has a melting point lower than 130 ° C. and is not suitable for the present invention. Polyimide, polyether imide, polyether ether ketone, ethylene tetrafluoroethylene copolymer, hexafluoropropylene, and perfluoroalkyl vinyl ether copolymer are not suitable for the present invention because their melting points are higher than 260 ° C.

  Among the thermoplastic resins used in the endless belt of the present invention, the crystalline resin preferably has at least one of a hydroxyl group, a carboxylic acid group and an ester bond, and has a crystallinity of 20% or more and less than 90%. If it is, there will be no restriction | limiting in particular and a general purpose resin can be used.

  Specifically, among the thermoplastic crystalline resins, PAT (polyalkylene terephthalate) is preferable, and PBT (polybutylene terephthalate), PET (polyethylene terephthalate) and PEN (polyethylene naphthalate) are more preferable, and PBT is crystallized. Since the speed is high, there is little change in crystallinity due to molding conditions, and it is particularly preferable because it is generally stable at a crystallinity of around 30%.

  Moreover, a copolymerization component can also be introduce | transduced in the crystalline resin used for this invention 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 crystalline resin used in the endless belt of the present invention, a resin having a general molecular weight such as a weight average molecular weight of 10,000 to 100,000 can be used, but mechanical properties such as tensile elongation at break are high. When required, high 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.

  Among the thermoplastic resins used in the endless belt of the present invention, the amorphous resin preferably has at least one of a hydroxyl group, a carboxylic acid group and an ester bond, and has a crystallinity of 0% or more and 10%. If it is less than this, there will be no restriction | limiting in particular and a general purpose resin can be used.

  Specifically, polyesters such as PC (polycarbonate) and PAr (polyarylate), and resins having ester bonds in the side chains such as PMMA (polymethyl methacrylate) can be given as suitable examples. Of these, polyester is preferable, and PC can be used particularly preferably.

  The amorphous resin used for the endless belt of the present invention can introduce a copolymer component within a range that does not significantly impair the effects of the present invention. Specific examples include those in which an ester bond is a main chain and an ester bond such as polymethylene glycol is introduced.

  The molecular weight of the amorphous resin used in the endless belt of the present invention is not particularly limited. For example, a resin having a general molecular weight such as a weight average molecular weight of 10,000 to 100,000 can be used. When there is a demand for high physical properties, those having a high molecular weight are preferred. Specifically, it is preferably 20,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more.

(Thermoplastic elastomer)
As the thermoplastic elastomer used in the present invention, thermoplastic elastomers such as polyester, polyamide, polyether, polyolefin, polyurethane, and vinyl chloride can be used.

  The feature of the thermoplastic elastomer is that the crack resistance of the endless belt can be greatly enhanced and flexibility can be imparted.

(Alloy material of thermoplastic resin and thermoplastic elastomer)
When an alloy material of a thermoplastic resin and a thermoplastic elastomer is used as the thermoplastic polymer component, the thermoplastic elastomer has a common functional group with the thermoplastic resin and has high affinity with the thermoplastic resin. By using an elastomer, the alloy dispersibility of the thermoplastic resin and the thermoplastic elastomer is improved, the crack resistance can be dramatically improved and the tensile elastic modulus can be adjusted. Excellent surface smoothness, carbon black, etc. The conductive material dispersibility is obtained, which is preferable.

  Accordingly, when a polyester such as polybutylene terephthalate or polyethylene terephthalate and / or polycarbonate is used as the thermoplastic resin, it is preferable to use a polyester-based or polyether-based thermoplastic elastomer. In addition, it is preferable to combine a polyamide-based thermoplastic elastomer with an amide-based thermoplastic resin such as nylon.

  The polyester elastomer block is a polyester polyether block copolymer using an aromatic polyester as a hard component, an aliphatic polyether as a soft component, an aromatic polyester as a hard component, and an aliphatic polyester as a soft component. Copolymers can be used.

  More specifically, the following (A) and (B) can be used as the polyester polyether block copolymer and the polyester polyester block copolymer.

(A) Polyester polyether block copolymer The polyester polyether block copolymer comprises (a) an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, and (b) an aromatic dicarboxylic acid or an alkyl ester thereof. And (c) Polyalkylene ether glycol having a weight average molecular weight of 400 to 6,000 as a raw material, and an oligomer obtained by esterification reaction or transesterification reaction is polycondensed. Examples of the aliphatic and / or alicyclic diol having 2 to 12 carbon atoms include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. Preferably, 1,4-butanediol and ethylene glycol are the main components, and one or a combination of two or more of these can be used.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and the like. Preferably, terephthalic acid and 2,6-naphthalenedicarboxylic acid are the main components. A combination of the above may also be used. 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.

  As the polyalkylene ether glycol, those having a weight average molecular weight of 400 to 6,000 are used, preferably 500 to 4,000. Here, as polyalkylene ether glycol, polyethylene glycol, poly (1,2 and 1,3-propylene ether) glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, block or random copolymer of ethylene oxide and propylene oxide And a block or random copolymer of ethylene oxide and tetrahydrofuran. Particularly preferred is polytetramethylene ether glycol. The content of the polyalkylene ether glycol is desirably 5 to 95% by weight, preferably 10 to 85% by weight, based on the block copolymer to be produced.

(B) Polyester polyester block copolymer The polyester polyester block copolymer is (d) an aliphatic or alicyclic dicarboxylic acid instead of the above (c) polyalkylene ether glycol having a weight average molecular weight of 400 to 6,000. And a polyester oligomer obtained by condensation of an aliphatic diol, (e) a polyester oligomer synthesized from an aliphatic lactone or an aliphatic monool carboxylic acid, and (a) an aliphatic and / or alicyclic group having 2 to 12 carbon atoms. A diol and (b) an aromatic dicarboxylic acid or an alkyl ester thereof are used as raw materials, and an oligomer obtained by an etherification reaction or a transesterification reaction is polycondensed.

  Examples of the above (d) 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 and one or more diols such as ethylene glycol, propylene glycol, tetramethylene glycol, and pentamethylene glycol are condensed. Examples of e) include polycaprolactone-based polyester oligomers synthesized from ε-caprolactone, ω-oxycaproic acid and the like.

  Specific examples of thermoplastic elastomers other than polyesters used in the present invention include those based on polystyrene, such as styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, styrene- There are ethylene-propylene-styrene copolymers, etc., and in the case of polyvinyl chloride, there are cross-linked (three-dimensional) vinyl chloride-linear vinyl chloride polymers, etc., and as olefins, there are polyethylene-EPDM copolymer, polypropylene-EPDM copolymer, polyethylene- There are EPM copolymer polypropylene-EPM copolymer, etc., and PBT (1,4-butadienediol-terephthalic acid condensate) -PTMEGT (polytetramethyleneglycol) (Poly-terephthalic acid condensate) copolymer and the like, and examples of the polyamide system include a copolymer having a basic skeleton of nylon oligomer-dicarboxylic acid-polyether oligomer, and examples of the nylon oligomer include nylon 6 and nylon. 66, nylon 610, nylon 612, nylon 11, nylon 12, and the like. As the polyether oligomer, for example, polyether glycol, polypropylene glycol, polytetramethylene glycol and the like can be used. Examples of the urethane system include a polyurethane-polycarbonate polyol copolymer, a polyurethane-polyether polyol copolymer, a polyurethane-polycaprolactone polyester copolymer, and a polyurethane-adibate polyester copolymer.

  When an alloy material of a thermoplastic resin and a thermoplastic elastomer is used as the thermoplastic polymer component, the weight ratio of the thermoplastic resin and the thermoplastic elastomer is not particularly limited. However, among thermoplastic resins, crystalline resins are generally excellent in chemical resistance and flex resistance, and amorphous resins are excellent in molding dimensional stability. Therefore, the ratio to thermoplastic elastomer is set according to the purpose of use. Among them, the weight ratio of thermoplastic resin / thermoplastic elastomer is preferably 1/99 to 99/1, more preferably 5/95 to 95/5, and still more preferably 10/90 to 90/10. 70/30 to 30/70 are particularly preferable, and 60/40 to 40/60 are particularly preferable.

  In this case, if the difference in viscosity between the thermoplastic resin and the thermoplastic elastomer is too large, even if the production conditions are adjusted, good dispersion may not be obtained, and uniform dispersion may not be achieved. Is preferably smaller. 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.

  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 JISK-7210 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.

(Melting point of thermoplastic polymer component)
In the present invention, it is preferable to use a thermoplastic polymer component having a melting point of 130 ° C. or higher and 260 ° C. or lower according to the following DSC measurement.
DSC (Differential Scanning Calorimetry) Measurement Using SSC-5200 (trade name) manufactured by Seiko Denshi Kogyo Co., Ltd., the sample was heated to 400 ° C. at a heating rate of 20 ° C./min, and the melting peak temperature was determined by DSC measurement. The melting point.

If the melting point of the thermoplastic polymer component is too low, the heat resistance of the endless belt to be obtained is deteriorated, and not only the trace of the roller is easily made but also the creep property is deteriorated. Conversely, if the melting point of the thermoplastic polymer component is too high, the molding temperature at the time of heat-kneading and heat-extrusion is too high, and the appearance of the belt surface may be roughened due to volatilization of the added component.
The melting point of the thermoplastic polymer component is more preferably 180 ° C. or higher and 250 ° C. or lower, more preferably 200 ° C. or higher and 240 ° C. or lower.

  In addition, as a thermoplastic polymer component, 1 type (s) or 2 or more types of thermoplastic resins may be used, 1 type (s) or 2 or more types of thermoplastic elastomers may be used, and these may be mixed and used.

<Antioxidant>
In the present invention, an antioxidant is blended in the molding material in order to prevent oxidative degradation due to thermal decomposition of the molding material in the heat-kneading or thermoforming process and deterioration with time during use. In addition, when blending a polymerization catalyst described later, if the activity of the polymerization catalyst is too high, the depolymerization of the thermoplastic polymer component is promoted, resulting in a decrease in mechanical properties due to a decrease in molecular weight, foaming due to the generation of a low molecular weight substance, etc. However, if a chelator having the ability to chelate the metal in the polymerization catalyst is present as an antioxidant, depolymerization can be suppressed, and therefore, in this respect, the addition of the antioxidant is preferable.

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

  Examples include phosphites, phosphates, phosphates, hydrazines, phenolic and sulfur antioxidants, such as Irgafos 168 (manufactured by Ciba Geigy Japan). , PEP36 (Asahi Denka Kogyo Co., Ltd.), Sandstub P-EPQ (Clariant Japan K.K.) phosphorous ester, IRGANOX MD1024 (Nippon Ciba Geigy Co., Ltd.), CDA-6 (Asahi Denka Kogyo Co., Ltd.) Hydrazines, Sumilizer BP101 (manufactured by Sumitomo Chemical Co., Ltd.), Irganox 1010 (manufactured by Nippon Ciba-Geigy Co., Ltd.), Adeka Stub AO-80 phenol, Sumilizer TPS (manufactured by Sumitomo Chemical) Yoshinox DMTP (manufactured by API), Anthiox S (manufactured by NOF Corporation), etc. It can be easily obtained from the market.

  In the present invention, the content of the antioxidant is preferably 0.01 parts by weight or more with respect to 100 parts by weight of the total thermoplastic polymer component, and 0.1 parts by weight or more for obtaining a better addition effect. It is preferable that

  If the content of the antioxidant is too small, the effect of adding the antioxidant as described above cannot be obtained sufficiently, but if it is too much, the excessive antioxidant will bleed on the belt surface and prevent the blade from being oxidized. Adherence of the agent causes poor cleaning. In addition, since the polymerization catalyst loses activity and an endless belt with good physical properties may not be obtained, it is preferable not to add excessively, and preferably 5 parts by weight or less with respect to 100 parts by weight of the total thermoplastic polymer component, 3 parts by weight or less is more preferred, and 0.5 parts by weight or less is even more preferred.

  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 0.1 to 5 parts by weight, preferably 0.3 to 3 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component. If the molding conditions (temperature, residence time, etc.) for obtaining an endless belt are further optimized by using a higher amount than the range and common sense, chemical bond formation and molecular weight increase between the thermoplastic resin and the thermoplastic elastomer will be promoted. In addition, while suppressing depolymerization, it is possible to prevent the decomposition of additional components, and an endless belt having excellent physical properties that has never been obtained can be obtained.

<Heat-treated fluororesin fine particles>
The fluororesin fine particles used in the present invention are obtained by heat-treating and then pulverizing fluororesin fine particles synthesized according to a conventional method.

(Fluorine resin types)
The type of fluororesin constituting the fluororesin fine particles is preferably not particularly limited as long as the physical properties described below are satisfied. Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polychlorotrimethyl Fluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer, tetrafluoroethylene-hexafluoro A propylene copolymer (FEP), a tetrafluoroethylene-ethylene copolymer (ETFE), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), or the like can be used.
Two or more types of these fluororesins may be finely divided.
Among these fluororesins, it is preferable to use PTFE because it has a particularly small surface energy and is effective in improving toner transfer properties and toner cleaning properties.

(Heat treatment conditions)
The heat treatment temperature of the fluororesin is preferably 5 ° C. or more higher than the melting point of the fluororesin.
That is, as described above, the fluororesin becomes fine particles having a uniform particle size by subsequent heat treatment, and does not fibrillate when subjected to shear during kneading or extrusion. However, if the heat treatment temperature is too low, such an effect cannot be sufficiently obtained, so that the heat treatment temperature is preferably high to some extent. . However, since the fluororesin may be decomposed when the heat treatment temperature is too high, the heat treatment temperature is 5 to 200 ° C. higher than the melting point of the fluororesin, particularly 10 to 100 ° C. higher than the melting point of the fluororesin. It is preferable that

There is no particular limitation on the heat treatment time, but if it is too short, the above-mentioned effect due to the heat treatment cannot be sufficiently obtained, and if it is too long, an effect commensurate with the treatment time cannot be obtained, industrial production. Since it is disadvantageous in terms of sex, it is preferably about 30 minutes to 24 hours.
The atmosphere of the heat treatment is usually an air atmosphere.
In addition, you may irradiate a fluororesin after the said heat processing in order to adjust melting | fusing point and 5% weight loss temperature (molecular weight) of a fluororesin.

  Further, if the fluororesin fine particles are treated under the above-described conditions, the fluororesin fine particles are fused with each other, and thus need to be pulverized. The pulverization can be performed in various pulverizers such as a jet mill, a ball mill, a roller mill, a rod mill, a hammer mill, and the like. It is preferable to use heat-treated fluororesin fine particles.

  The fluororesin fine particles obtained by such heat treatment and pulverization are in the form of fine particles close to rounded spheres and have high hardness, so that there are few problems of fibrillation in the molding process. Further, the heat treatment makes it difficult for the fine particles to aggregate and prevents the occurrence of convex defects on the belt surface due to the fine particle aggregation, thereby improving the surface smoothness and toner cleaning property of the belt.

(Melting point)
The melting point of the fluororesin constituting the fluororesin fine particles is preferably higher by 10 ° C. or more than the melting point of the thermoplastic polymer component. If the melting point of the fluororesin is low, the fluororesin fine particles may be fibrillated or bleed out in the molding process, so that the intended purpose cannot be achieved. The higher the melting point of the fluororesin, the better. However, a normal fluororesin has a melting point higher by about 10 to 150 ° C. than the melting point of the thermoplastic polymer component.
In addition, melting | fusing point of a fluororesin can be measured by above-mentioned DSC (differential scanning calorie | heat amount).

(5% weight loss temperature in thermogravimetry)
The 5% weight loss temperature in thermogravimetry is an index of the molecular weight of a polymer substance. A material having a high 5% weight loss temperature has a large molecular weight, and a material having a low 5% weight loss temperature has a small molecular weight.

  The fluororesin constituting the fluororesin fine particles used in the present invention preferably has a 5% weight loss temperature in thermogravimetry of 550 ° C. or less, particularly 350 to 500 ° C. The molecular weight of the fluororesin having a 5% weight loss temperature of 500 ° C. or less, particularly 350 to 500 ° C., is usually 1 million or less, particularly about 1 to 100,000.

In this way, by using fine particles of a low molecular weight fluororesin, it is possible to suppress an increase in the viscosity of a molding material in which this is blended and to maintain extrusion moldability. That is, as a conventional fluororesin, those having a molecular weight exceeding 1 million, for example, a high molecular weight having a molecular weight of about 4,000,000 are used. The viscosity of the material becomes too high, and in some cases extrusion is impossible.
In addition, the 5% weight loss temperature in the thermogravimetric measurement of the fluororesin is measured by heating the fluororesin at a temperature rising rate of about 10 ° C./min in an air atmosphere using a normal thermogravimetric measuring device (TG). be able to.

(Particle size / size distribution)
The average particle diameter of the fluororesin fine particles is preferably 0.1 to 10 μm, particularly preferably 0.3 to 8 μm, and particularly preferably 1 to 6 μm. If the average particle size of the fluororesin fine particles is too large, the interface with the base polymer becomes large and the crack resistance tends to deteriorate. Further, the bleeding effect of the fluororesin fine particles is reduced and the effect of improving the toner cleaning property is reduced. Further, convex defects are generated on the belt surface due to the fluororesin fine particles, the surface smoothness is impaired, and toner cleaning is defective. If the average particle size is too small, the fine particles aggregate in van der Waalska, the fluororesin fine particles cause poor dispersion when the molding material is kneaded, and similarly, convex defects occur on the belt surface, causing toner cleaning failure. It becomes.

In addition, for the same reason as the upper limit of the average particle diameter, it is preferable that the maximum particle diameter of the fluororesin fine particles is smaller. The maximum particle diameter is 20 μm or less, particularly 12 μm or less, and a relatively large particle diameter exceeding 5 μm. The proportion of large particles is preferably 30% by weight or less, particularly preferably 10% by weight or less. For the same reason as the lower limit of the average particle diameter, the proportion of ultrafine particles having a particle diameter of 1 μm or less is preferably 30% by weight or less, particularly preferably 10% by weight or less.
The particle size of the fluororesin fine particles can be measured by a laser diffraction scattering method, for example, a microtrack particle size analyzer manufactured by Nikkiso Co., Ltd.
In the present invention, the average particle size of the fluororesin fine particles refers to a 50% average particle size (d ₅₀ ), that is, a particle size of 50% integrated value from the minimum particle size.

(Mixing ratio)
In the present invention, the blending ratio of the heat-treated fluororesin fine particles is 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, more preferably 100 parts by weight of the thermoplastic polymer component. 1 to 7 parts by weight. When the blending ratio of the fluororesin fine particles is too large, the viscosity of the molding material increases and the extrusion moldability deteriorates. Further, by blending a large amount of a fluororesin having a low surface energy and poor mixing with the thermoplastic polymer component, peeling occurs at the interface with the thermoplastic polymer component, and the mechanical strength of the resulting endless belt decreases. On the other hand, if the blending ratio of the fluororesin fine particles is too small, the friction between the cleaning member and the belt increases, so that the toner scraping effect by the cleaning blade is reduced and cleaning failure is likely to occur. Further, the lubricant effect of the antioxidant bleed on the belt surface is reduced, and the antioxidant easily adheres to the blade, so that cleaning failure is likely to occur.

  A more preferable blending ratio of the fluororesin fine particles is 1 to 100 times by weight, particularly 5 to 50 times by weight with respect to the above-mentioned antioxidant in the above range. When the blending ratio of the fluororesin fine particles with respect to the antioxidant is too small, the effect of the lubricating agent of the antioxidant bleed on the belt surface cannot be obtained sufficiently. This is not preferable because it leads to a decrease in mechanical strength.

<Conductive substance>
By adding a conductive substance to the endless belt, the endless belt can be provided with conductivity and the degree of conductivity can be adjusted.

  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, as the conductive filler, carbon black, carbon fiber, graphite, etc. Carbon-based fillers, metal-based conductive fillers, metal-oxide-based conductive fillers, and the like are used. In addition to the conductive fillers, ionic conductive substances such as quaternary ammonium salts are exemplified. Among conductive materials, it is preferable to use carbon black because the humidity dependency of the electrical resistivity tends to be reduced. Carbon black may be used in combination with other conductive materials such as an ion conductive material.

  Although the compounding quantity of an electroconductive component changes also with the kind of electroconductive component to be used, it is preferable to set it as 0.1-30 weight part with respect to 100 weight part of thermoplastic polymer components. If the blending amount of the conductive component is less than this range, a sufficient blending effect cannot be obtained, and if it is too large, the moldability and the like are impaired.

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, in order to control to the semiconductive region, it is necessary to have a blending accuracy within ± 0.05% and to make resistance variation of the endless belt 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 polymer component decomposes due to the reaction between the carbon black and the thermoplastic polymer component, resulting in foaming. This is undesirable 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.

<Polymerization catalyst>
In the present invention, when a thermoplastic resin and a thermoplastic elastomer are used in combination as a thermoplastic polymer component, a mixture of a thermoplastic resin and a thermoplastic elastomer, a mixture of them from a polymerization stage, and a reaction with a catalyst. Although known alloying techniques such as mixing while mixing can be used, heating and mixing using a polymerization catalyst is most preferable from the viewpoint of cost.
The polymerization catalyst is not particularly limited as long as it has the ability to polymerize thermoplastic resins and thermoplastic elastomers.

  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.

  Although there is no restriction | limiting in particular as a compound containing magnesium, Organic acid magnesium salt is preferable and magnesium acetate is especially preferable.

  If the amount of the polymerization catalyst used is too small, it may not work effectively. Therefore, it is preferable that the polymerization catalyst is used to a certain 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”.

<Other optional ingredients>
In the endless belt of the present invention, optional blending components other than the above can be blended according to various purposes.

  Specifically, waxes, heat stabilizers, various plasticizers, light stabilizers, UV absorbers, neutralizers, lubricants, antifogging agents, antiblocking agents, slip agents, crosslinking agents, crosslinking aids, colorants, Various additives such as a flame retardant, a dispersant, a compatibilizer, a thickener, an anti-drip agent, a catalyst deactivator, and a fluidity improver 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.

(2) Endless belt manufacturing method <Heat kneading and molding>
In the present invention, the thermoplastic polymer component, antioxidant and heat-treated fluororesin fine particles, more preferably a conductive material, and optionally other optional components are heated and kneaded to obtain a thermoplastic resin. The endless belt may be formed after forming the composition, or the endless belt may be formed as it is by heating and kneading them. However, in the heat-kneading of the molding material, the antioxidant and the fluororesin fine particles are mixed sufficiently sufficiently in advance, and as a mixture in a state where the antioxidant is adhered to the surface of the fluororesin fine particles like a dusting powder, It is preferable to knead with a thermoplastic polymer component or the like. Thus, by previously mixing the antioxidant and the fluororesin fine particles, it is possible to enhance the lubricant effect of the antioxidant by the fluororesin fine particles.

  Also, the kneading conditions are adjusted so that the desired surface electrical resistivity can be obtained, either by heat kneading at the stage of obtaining the thermoplastic resin composition or by heat kneading at 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, when a thermoplastic elastomer and a thermoplastic resin are used in combination as the thermoplastic polymer component, a specific dispersion state of the thermoplastic elastomer and the thermoplastic resin is a good dispersion of the conductive material and the surface of the endless belt. It is considered that an endless belt excellent in both toner transferability and releasability can be obtained. Therefore, 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. The index of the alloy state at that time is a voltage dependency characteristic of electric resistivity, which will be described later, a variation in electric resistivity, and a ratio between surface electric resistivity and volume electric resistivity.

  There is no particular limitation on the heating and kneading means, and a known technique can be used. For example, if a thermoplastic polymer component, a mixture of an antioxidant and fluororesin fine particles, a conductive component blended as necessary, and other additive components are heated and kneaded to obtain a resin composition, uniaxial extrusion A machine, a twin-screw kneading extruder, a Banbury mixer, a roll, a Brabender, a plastograph, a kneader, or the like can be used. In particular, a method in which these are mixed, for example, by a twin-screw kneading extruder, pelletized, and then formed 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, the inner cooling mandrel system is most preferable as a method for forming an endless belt for an image forming apparatus because a seamless endless belt can be easily obtained. 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 of 0.1 g / 10 min or more in terms of MFR value (240 ° C., 2.16 kgf load). When the melt viscosity of the molding material is less than 0.1 g / min MFR, the fluidity at the time of extrusion molding is poor, and in addition to difficulty in extrusion molding, the shear stress applied to the molten resin is increased, so resistance adjustment is difficult. However, when 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 cooling and solidification, and therefore it is preferably 25 g / 10 min or less. It is preferably 5 to 20 g / 10 minutes. Therefore, it is preferable to adjust the viscosity with a viscous polymer 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 thermoplastic polymer component to be used, it 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.

(3) Physical properties of endless belt <Surface electrical resistivity and volume electrical resistivity>
The endless 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),
It is preferable that the following expressions (a), (b) and (c) are satisfied.
Formula (a): SR (100 V) / SR (500 V) <VR (100 V) / VR (250 V)
Formula (b): SR (100 V) / SR (500 V) ≦ 100
Formula (c): 5 ≦ VR (100 V) / VR (250 V) ≦ 300

  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 100 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"). There is a 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 5 to 300. Is preferably 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, but the rate of change in volume electrical resistance is greater than the rate of change in surface electrical resistance. 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 resistance change rate VR (100 V) / VR (250 V) is Within 300 times, preferably within 100 times. The lower limit of the volume electric resistance change rate VR (100 V) / VR (250 V) is 5 or more, particularly 10 or more in terms of exhibiting the effect of giving the belt a self-discharge function.

Accordingly, the endless belt for an image forming apparatus of the present invention preferably satisfies the following formulas (a ′), (b ′), and (c ′).
Formula (a ′): SR (100 V) / SR (500 V) × 2 ≦ VR (100 V) / VR (250 V)
Formula (b ′): 5 ≦ SR (100 V) / SR (500 V) ≦ 10
Formula (c ′): 10 ≦ VR (100 V) / VR (250 V) ≦ 100

The resistance region of the endless belt for an image forming apparatus of the present invention varies depending on the purpose of use, but the surface electrical resistivity 1 × 10 ⁶ × 10 ¹⁴ Ω or the volume electrical resistivity 1 × 10 ⁶ to 1 × 10 ¹⁴ Ω · It is selected from the range of cm.

Although the more preferable range of the resistance region varies depending on the application, for example, when used as a photoreceptor belt, the surface electrical resistivity 1 × 10 ¹ to 1 × 10 ⁹ so that the charge on the outer surface can be released to the inner surface as necessary. Low resistivity such as Ω or volume electrical resistivity 1 × 10 ¹ to 1 × 10 ⁹ Ω · cm is preferable, and when used as an intermediate transfer belt, surface electrical resistivity 1 × 10 ⁶ to 1 that can be easily charged and transferred. × 10 ¹³ Ω or volume electric resistivity 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm is preferable, and when used as a transfer transfer belt, it is easily charged and is not easily damaged even at a high voltage. 1 × 10 ¹⁰ to 1 × 10 ¹⁶ A high region such as Ω or volume resistivity 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm is preferable.

  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 can be easily measured by, for example, “HIRESTA”, “Loresta” manufactured by Dia Instruments Co., Ltd., or “R8340A” manufactured by Advantest Corporation. Can do.

<Tensile modulus>
The tensile elastic modulus of the endless belt of the present invention is preferably 300 MPa or more and 2300 MPa or less. 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. It is not preferable because it is easy to enter and there is a problem in reliability. 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, the preferable range of tensile modulus is 300 MPa or more and 2300 MPa or less, particularly 500 MPa or more and 2000 MPa or less, and particularly preferably 600 MPa or more and 1800 MPa or less.

  The tensile elastic modulus of the endless belt is adjusted from the viewpoint of improving the transfer efficiency of the toner. As described above, the effect of improving the transfer efficiency of the toner due to the chemical characteristics (contact angle with water) of the belt surface and the toner due to the electrical characteristics The most appropriate range may be determined in relation to the transfer 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 70 ° or more and 90 ° or less. If the contact angle of the outer surface with water is less than 70 °, the toner adheres to the belt surface and forms a film, which deteriorates the toner secondary transfer efficiency. On the other hand, if it exceeds 90 °, the transfer efficiency of the toner 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 70 ° or more and 90 ° or less, 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 0.03 μm or more and 0.17 μm or less. When the surface roughness Ra is less than 0.03 μm, the toner primary transfer efficiency is deteriorated. On the other hand, if it exceeds 0.17 μm, the secondary transfer efficiency of the toner deteriorates. Accordingly, the surface roughness Ra of the endless belt of the present invention is preferably 0.03 μm or more and 0.17 μm or less, particularly 0.05 μm or more and 0.15 μm or less.

<Folding 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 and alloying, the folding endurance of 50,000 times or more, and even 100,000 or more can be obtained. In order to prevent cracks from the end of the endless belt, It is preferable because sufficient crack resistance can be obtained without performing secondary processing such as a commonly used reinforcing tape for preventing cracks.

<Roller-resistant>
The roller wrinkle resistance of the endless belt of the present invention preferably has a roller wrinkle restoration rate of 25% or more determined in accordance with a roller wrinkle resistance evaluation method described later. If the anti-roller wrinkle is smaller than these condition ranges, the roller trace remaining on the endless belt may cause image unevenness. A more preferable roller-resistant wrinkle is 30% or more in terms of the roller wrinkle restoration rate, and particularly preferable is 35% or more.

(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 cracked. 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.

(5) Application of endless belt for image forming apparatus The application of the endless belt for image forming apparatus of the present invention is not particularly limited. It can use suitably for a member. When this endless belt is formed in a seamless belt shape, there are few problems such as cracking and elongation, which is preferable.

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

  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 the 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.

  Examples 1 to 8, Comparative Examples 1 to 3, and Reference Example 1 are given below to show the effects of the present invention.

<material>
The following materials were used, and the blending ratios were as shown in Tables 2 and 3.

(Thermoplastic resin)
・ PBT: "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 min. PC: “E2000” manufactured by Mitsubishi Engineering Plastics Co., Ltd.
Weight average molecular weight = 28,000
PS-converted weight average molecular weight = 64,000
MFR (280 ° C., 2.16 kgf load): 4.8 g / 10 minutes

(Thermoplastic elastomer)
-PEER: Toyobo Co., Ltd. polyester-polyester elastomer "Perp
Len S3001 "
MFR (240 ° C., 2.16 kgf load) = 21 g / 10 min
Crystal melting point = 216 ° C

(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

(Polymerization catalyst)
Titanium (IV) butoxide / magnesium acetate

(Antioxidant)
Phosphorylation inhibitor “PEPQ” manufactured by Clariant Japan

(Fluorine resin fine particles)

In addition, the measuring method of the physical property of fluororesin fine particles is as follows.
Particle size: 50% particle size was defined as the average particle size (d ₅₀ ) at a measurement time of 30 seconds using a laser diffraction scattering particle size analyzer Microtrac “MT3300” manufactured by Nikkiso Co., Ltd.
Melting point: “SSC-5200” manufactured by Seiko Denshi Kogyo Co., Ltd. was used and measured at a rate of temperature increase of 20 ° C./min.
5% weight loss temperature: By thermogravimetric analysis (TG), the temperature was raised to 30 to 540 ° C. in the air at a heating rate of 10 ° C./min, and the temperature at the time of 5% weight loss was determined.

  In addition, melting | fusing point calculated | required by DSC measurement about the thermoplastic polymer component was as Tables 2 and 3.

<Heat kneading>
Each raw material was pelletized using a twin-screw kneading extruder (“PMT32” manufactured by IKG Corporation). The kneading conditions were based on a cylinder temperature of 260 ° C., but were adjusted in the range of 220 ° C. to 260 ° C. except that the cylinder temperature of the kneading part where the temperature of the molten resin rises midway was set to 130 ° C. to 150 ° C. . The fluororesin fine particles and the antioxidant were dry blended in advance and used as a mixture.

<Endless belt molding method>
This material pellet was dried, and the annular die was formed by a 40 mmφ extruder with six-spiral annular die having a diameter of 190 mm and a die slip width of 1.0 mm (having 16 temperature control mechanisms in the circumferential direction of the annular die). While extruding downward in a molten tube state, the extruded molten tube is cooled and solidified while being in contact with the outer surface (temperature 90 ° C.) of a cooling mandrel having an outer diameter of 184 mm mounted on the same axis as the annular die via a support rod, Next, with a cylindrical core installed in the seamless belt and a 4-point belt type take-up machine installed on the outside, a length of 300 mm is taken while the seamless belt is being held in a cylindrical shape. 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 ¹¹ Ω. A seamless belt having an inner diameter of 183 mm was prepared. Extrusion conditions were such that the cylinder and die temperature were both 260 ° C. as basic conditions.

<Evaluation>
The evaluation was carried out by cutting the endless belt to the required size as required, and the results are shown in Tables 2 and 3.

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

-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 500 V and 10 seconds.

-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.

・ Bending resistance (bending resistance)
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.
As a criterion for pass / fail evaluation of folding resistance, 20,000 times or more was evaluated as ◎, 10,000 times or more and less than 20,000 times as ○, 1000 times or more and less than 10,000 times as Δ, and less than 1000 times as ×.

-Wetting tension Wetting tension of the outer surface of the endless belt was measured based on JIS K6768-1995 using a reagent for wetting test made by Wako Pure Chemical Industries, Ltd. consisting of a mixed solution of formamide and ethylene glycol monoethyl ether.
This value indicates that the lower the value, the smaller the surface energy of the belt.

・ Surface roughness (Ra)
The outer surface of the endless belt is cut into a sample of about 50 mm × 50 mm, and measurement of 100 times lens, pitch 0.01 μm, shutter speed AUTO, and gain 835 is performed using the ultra-deep shape measurement microscope trade name “VK8500” manufactured by Keyence Corporation. Under the conditions, the surface roughness of an area of 40 μm × 40 μm was measured at four points, and the average value was taken as the measured value of the surface roughness.

・ Evaluation of cleaning performance Mount the transfer belt on the transfer belt unit of Ricoh's intermediate transfer tandem machine “CX3000”, attach the cleaning blade, and bring the waste toner into contact with the belt surface. Then, after the belt 10 is rotated, the number of toner remaining in a streak shape without being cleaned by the blade is counted. If this is 3 or less, ◎, if 4 or more and 5 or less, ○, 6 or more and 10 or less. △, and X in the case of 11 or more locations.

<Discussion>
Examples 1-8 use what was heat-processed as PTFE particle | grains, the compounding quantity is changed between 1-10 weight part with respect to 100 weight part of thermoplastic polymer components, and the compounding quantity of antioxidant is also used. Although it was changed between 0.3 and 1 part by weight with respect to 100 parts by weight of the thermoplastic polymer component, any of the endless belts had no problem with crack resistance and cleanability and was at a practical level.
On the other hand, in Comparative Example 1 in which no antioxidant is used, the folding resistance is poor because there is no antioxidant.
Even in the case where the antioxidant is blended, in Comparative Example 2 in which the PTFE fine particles are not blended, the cleaning property deteriorates due to bleeding of the antioxidant on the belt surface.
In Comparative Example 3 using PTFE fine particles that were not heat-treated, the PTFE fine particles are likely to aggregate, resulting in a large belt surface roughness and poor cleaning properties.
Even if the PTFE fine particles heat-treated with the antioxidant are blended, in Reference Example 1, since the particle size of the PTFE fine particles is large, the surface roughness of the belt becomes large and the cleaning property is poor.

  Based on the above results, by providing the thermoplastic polymer component with a predetermined amount of fluororesin fine particles that have been heat-treated with an antioxidant, an endless belt for image forming apparatus that is high in image quality and highly durable is provided. You can see that you can.

It is a side view of a general intermediate transfer device.

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

Claims (17)

An endless belt used in an image forming apparatus, wherein the endless belt mainly contains a thermoplastic polymer component made of a thermoplastic elastomer and / or a thermoplastic resin.
It contains an antioxidant and heat-treated fluororesin fine particles, and the content of the fluororesin fine particles is 0.1 to 20 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component. An endless belt for an image forming apparatus.   2. The endless belt for an image forming apparatus according to claim 1, wherein the heat treatment temperature of the fluororesin fine particles is a temperature higher by 5 ° C. or more than the melting point of the fluororesin.   3. The endless belt for an image forming apparatus according to claim 1, wherein the melting point of the fluororesin is 10 ° C. or more higher than the melting point of the thermoplastic polymer component.   4. The endless belt for an image forming apparatus according to claim 1, wherein the fluororesin fine particles have an average particle diameter of 0.1 to 10 μm.   5. The endless belt for an image forming apparatus according to claim 1, wherein a 5% weight loss temperature in thermogravimetric measurement of the fluororesin is 550 ° C. or less.   6. The endless belt for an image forming apparatus according to claim 1, wherein the content of the antioxidant is 0.01 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component. .   7. The endless belt for an image forming apparatus according to claim 1, wherein the content of the fluororesin fine particles is 1 to 100 times by weight of the antioxidant.   In any 1 item | term of the Claims 1 thru | or 7, the said fluororesin microparticles | fine-particles and antioxidant are mixed previously, This mixture is heat-kneaded with the said thermoplastic polymer component, a molding material is obtained, and this molding material is shape | molded. An endless belt for an image forming apparatus.   9. The endless belt for an image forming apparatus according to claim 8, wherein the endless belt is formed by pulling the molten material obtained by heating and extruding the molding material from an annular die while cooling or solidifying it.   The endless belt for an image forming apparatus according to any one of claims 1 to 9, further comprising 0.1 to 30 parts by weight of a conductive component with respect to 100 parts by weight of the thermoplastic polymer component.   11. The endless belt for an image forming apparatus according to claim 10, wherein the conductive material is carbon black.   In any 1 item | term of the Claims 1 thru | or 11, the said thermoplastic polymer component is a ratio of thermoplastic elastomer / thermoplastic resin = 5 / 95-95 / 5 by a weight ratio of a thermoplastic elastomer and a thermoplastic resin. An endless belt for an image forming apparatus.   The endless belt for an image forming apparatus according to any one of claims 1 to 12, wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.   The endless belt for an image forming apparatus according to any one of claims 1 to 13, wherein the thermoplastic resin contains polyalkylene terephthalate as a main component.   The endless belt for an image forming apparatus according to claim 14, wherein the polyalkylene terephthalate is polybutylene terephthalate.   16. The endless belt for an image forming apparatus according to claim 1, wherein the endless belt is an 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 endless belt for an image forming apparatus according to claim 1.

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