JP5082464B2 - Endless belt for image forming apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an endless belt for an image forming apparatus useful for an intermediate transfer belt, a transfer transfer belt, a photosensitive belt, etc. used in an electrophotographic copying machine, a laser beam printer, a facsimile machine, etc. The present invention relates to a seamless belt for an image forming apparatus excellent in cleaning performance by a cleaning blade and an image forming apparatus including the endless belt for an image forming apparatus.

  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.

Therefore, conventionally, the following techniques have been proposed to improve the surface characteristics of the endless belt in order to solve toner releasability and cleaning properties.
(1) Fluororesin is used for the endless belt (Japanese Patent Laid-Open No. 2002-365866)
(2) Covering the endless belt surface with a lubricating material (Japanese Patent Laid-Open No. 2-213881)
(3) The endless belt is coated with a fluorine-based paint (Japanese Patent Laid-Open No. 11-212374)
(4) Mix long-chain fatty acids at the endless belt molding (Japanese Patent No. 3473808)
(5) Adding a chain silicone resin to the endless belt (Japanese Patent Laid-Open No. 2005-31640)
(6) Carbon black, which is an endless belt filler, is surface-treated with silicone (Japanese Patent Laid-Open No. 2002-214927)

  As described in JP-A-2002-365866, when a fluororesin is used for the endless belt, the coefficient of linear expansion creeps greatly, so that when used while being stretched on a roller or the like, there is slack or wrinkles on the roller part. It is not preferable because it is attached. Further, it is not preferable to use a fluororesin as a main component because of high cost.

  Also, as disclosed in JP-A-2-238881, when a material having lubricity is coated on the surface of the endless belt, the material having lubricity coated on the surface is also scraped off with the cleaning of the toner by the cleaning blade. In other words, it is necessary to apply this for each use, which complicates the apparatus and increases the cost.

    In addition, as disclosed in JP-A-11-212374, when an endless belt is coated with a fluorine-based paint, the coating layer is peeled off due to use over time, and the cost is increased due to an increase in tact time such as coating, drying, and curing processes. This is not preferable.

  In addition, as disclosed in Japanese Patent No. 3473808, although adding a long chain fatty acid at the time of molding is very good in terms of cost, the long chain fatty acid has a low melting point, and depending on the temperature conditions, it causes bleed and extrusion molding. Sometimes surging occurs and foaming of the base resin occurs during molding of the endless belt, which causes a problem of roughening the endless belt surface.

  In addition, as in JP-A-2005-31040, the addition of a high molecular weight chain silicone resin has the same problem as in the case of a fluororesin. Since it does not react with the resin, bleed occurs and surging occurs during molding.

Further, as disclosed in JP-A-2002-214927, it is very effective to surface-treat carbon black with silicone, but this patent presupposes polypropylene as a base resin. On the other hand, when engineering plastics with heat resistance other than polyolefin are used as the base resin, the molding conditions are higher than when molding polyolefin, so the amount and type of silicone functional groups, molecular weight, Depending on the type of group, it is necessary to control the pH and processing conditions of carbon black.
JP 2002-365866 A JP-A-2-238881 JP-A-11-212374 Japanese Patent No. 3473808 Japanese Patent Laid-Open No. 2005-316040 JP 2002-214927 A

The present invention solves the above-mentioned conventional problems, and is an endless belt excellent in toner releasability and cleaning performance by a cleaning blade, and as a component that reduces surface tension in extrusion molding, which is a preferable method in terms of cost. To provide an endless belt for an image forming apparatus which does not cause surging due to the influence of silicone used, maintains easy moldability (high productivity), and does not cause appearance defects due to surface irregularities caused by foaming or the like. With the goal.
Another object of the present invention is to provide an image forming apparatus including such a seamless belt for an image forming apparatus.

  As a result of intensive studies to solve the above problems, the inventors of the present invention added silicone to carbon black and optionally reacted it before heating and mixing the thermoplastic polymer component and carbon black. It has been found that the dispersion is good, the surface unevenness is small, the toner releasability of the endless belt and the cleaning property by the cleaning blade can be improved while suppressing bleeding and foaming.

  In order to improve toner releasability, it is important to reduce the adhesion between the toner and the transfer belt and to increase the cleaning efficiency by the cleaning blade. In the present invention, the surface tension of the endless belt is reduced as a measure for reducing the toner adhesion force while suppressing the unevenness of the belt surface within a range where the cleaning efficiency is not lowered.

  When an endless belt is manufactured by extrusion, it can be produced at a very low cost because it is a continuous process. However, in order to improve toner releasability, when a material for lowering the surface tension (hereinafter sometimes referred to as “surface tension reducing substance”) is mixed with the molding material, the thermoplastic polymer component as the substrate and the surface Since the energy is greatly different (especially when the thermoplastic polymer component is polyester, polyamide, polyether, etc.), the surface tension reducing substance bleeds to the belt surface without mixing. Therefore, the bleed surface tension reducing substance becomes a lubricant, and the pellet slips when the resin is put into the extruder, and a pulsation phenomenon called surging (the resin is discharged or not) occurs. When surging occurs, the thickness of the endless belt will change and productivity will drop, or air will be involved and the resin will be extruded, which may cause poor appearance such as foaming (traces of gas on the film surface). It becomes.

  On the other hand, there are fine powder fluororesin, silicone rubber, ultrahigh molecular weight polyethylene, etc. as surface tension reducing substances which are difficult to bleed. In the case of base resins such as polyester and polyamide, these are not melted at the temperature at the time of heating and mixing, and are dispersed like fillers. Since it is a substance, its surface energy is greatly different from that of the thermoplastic resin as a base material, and it is unevenly distributed as an aggregate on the belt surface without being mixed. For this reason, since the surface irregularities become large, a cleaning failure occurs when used as a transfer belt or the like.

  If these surface tension reducing substances are used at a temperature at which they are melted, the heating and mixing temperature will be too high, so the molecular weight of the main component polyester or polyamide will decrease, impairing the carbon black dispersibility, When it is used as a belt, it is not preferable because durability and the like are lowered.

Therefore, the present inventors, as a method for improving the toner releasability of the endless belt in the extrusion molding that is advantageous in terms of cost, while suppressing the bleeding to the belt surface, without causing aggregation and generation of fuzz, As a result of investigating the method of mixing the surface tension reducing substance, before heating and mixing the thermoplastic polymer component, which is the main component, and carbon black, the carbon black is pre-added with silicone as the surface tension reducing substance and then heated. A method of mixing was found.
The present invention has been achieved based on the above findings, and the gist thereof is as follows.

[1] An endless belt for use in an image forming apparatus, the main component of which is a thermoplastic polymer component made of a thermoplastic resin and / or a thermoplastic elastomer, and the thermoplastic polymer component and carbon black are mixed by heating and extruded. In the endless belt for an image forming apparatus obtained by molding, the pH of the carbon black is 4 or more, and prior to the heat mixing of the thermoplastic polymer component and carbon black, silicone is attached to the carbon black, An endless belt for an image forming apparatus, wherein the functional group equivalent of the silicone is 500 g / mol or more.

[2] An endless belt for an image forming apparatus according to [1], wherein the thermoplastic polymer component has an ester bond.

[3] The endless belt for an image forming apparatus according to [1] or [2], wherein the average molecular weight of the silicone is 100 or more and less than 100,000.

[4] In any one of [1] to [3], the content of the silicone is 100 parts by weight in total of a thermoplastic polymer component made of a thermoplastic resin and / or a thermoplastic elastomer and carbon black. An endless belt for an image forming apparatus, which is 0.1 to 10 parts by weight.

[5] [1] to A method according to any one of [4], the carbon black, DBP oil absorption 50~300cm ³ / 100g, a specific surface area 35~500m ² / g, volatile content 0-20%, average primary particle size An endless belt for an image forming apparatus, characterized by satisfying 20 to 50 nm.

[6] The endless belt for an image forming apparatus according to any one of [1] to [5], wherein the carbon black is acetylene black.

[7] The endless belt for an image forming apparatus according to any one of [1] to [6], wherein the surface roughness Ra is 0.02 μm <Ra <0.25 μm.

[8] In any one of [1] to [7], the melt viscosity indicated by the melt flow rate (MFR) of the extruded material is 0.1 g / 10 min or more. Endless belt for equipment.

[9] The endless belt for an image forming apparatus according to any one of [1] to [8], wherein the thermoplastic polymer component includes polyalkylene terephthalate.

[10] An image forming apparatus comprising the endless belt for an image forming apparatus according to any one of [1] to [9].

  According to the present invention, chemical and physical properties excellent in toner releasability and cleaning properties can be obtained without lowering the mechanical strength and without deteriorating the surface roughness. Thus, it is possible to provide an endless belt for an image forming apparatus that has excellent mechanical characteristics and surface characteristics such as excellent image quality, and excellent toner releasability and toner cleaning properties.

  The thermoplastic polymer component is preferably a polar polymer having an ester bond in order to disperse fillers such as carbon black, and in particular, polybutylene terephthalate, polyester elastomer, polycarbonate and the like are nonpolar polymers as the polymer having an ester bond. It is preferable to remove the polyolefin, because it is the cheapest. Further, particularly in the present invention, the purpose is to disperse silicone by adhering to carbon black. Therefore, the dispersibility of the carbon black in the thermoplastic polymer is essential, so that the thermoplastic polymer component has an ester bond. It is desirable to have. (Claim 2).

  The average molecular weight of the silicone used is preferably 100 or more and less than 100,000 (Claim 3).

  Moreover, it is preferable that the addition amount of silicone is 0.1-10 weight part with respect to a total of 100 weight part of a thermoplastic polymer component and carbon black (Claim 4).

Further, carbon black, DBP oil absorption amount 50~300cm ³ / 100g, a specific surface area of 35~500m ² / g, a volatile matter content of 0-20%, preferably used having an average primary particle diameter satisfies a 20~50nm In particular, the carbon black is preferably acetylene black (claim 6).

  The surface roughness Ra of the endless belt of the present invention is preferably 0.02 μm <Ra <0.25 μm (Claim 7).

  Moreover, it is preferable that the melt viscosity shown by the melt flow rate (MFR) of the material used for extrusion molding is 0.1 g / 10 min or more (Claim 8).

  The thermoplastic polymer component preferably contains polyalkylene terephthalate (claim 9).

  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 10).

  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.

  In the present invention, silicone having a functional group equivalent of 500 g / mol or more is preliminarily attached to carbon black before being heat-mixed with the thermoplastic polymer component, thereby preventing bleeding during molding of the endless belt or after molding. By dispersing, the silicone is also uniformly dispersed to prevent agglomeration on the belt surface, and the surface roughness is small and the surface property is excellent. In addition, the silicone content is 0.1 to 10 parts by weight with respect to a total of 100 parts by weight of the thermoplastic polymer component and the carbon black, and the molecular weight is 100 to 100,000, so that the carbon can be efficiently obtained. Grafted on black to prevent surface irregularities of foaming gas traces caused by deterioration of thermoplastic polymer components due to unreacted functional groups and improve toner releasability.

[About silicone]
In the present invention, silicone having a functional group equivalent of 500 g / mol or more is used.
Here, the functional group equivalent is a substance amount of the compound per mole of the functional group, expressed in g / mol, and assumed in the peak measured by nuclear magnetic resonance spectroscopy (NMR). From the ratio between the peak (area) of the functional group and the peak (area) of silicone.

  The functional group means a hydroxyl group, amino group, carboxyl group, halogen group, ester group, alkoxy group, imide group, epoxy group, methacryl group, carbodiimide group, carbonyl group, etc. , Refers to those introduced for the purpose of improving the compatibility with the polymer.

  In addition, as a method for synthesizing functionalized silicones, for example, in the case of general amino-modified silicones, equilibration is performed using siloxane oligomers obtained by hydrolysis of aminoalkylmethyldimethoxysilane, cyclic siloxanes and disiloxanes, and basic catalysts. The method of making it react is mentioned. Alternatively, a functional silicone can be synthesized by using a hydrolyzate of aminoalkylmethyldimethoxysilane, a siloxane having silanol groups at both ends, and a basic catalyst.

  If the functional group equivalent of silicone is too small, that is, if the amount of functional groups is too large, it cannot be used for grafting to carbon black, and unreacted functional groups deteriorate the thermoplastic polymer component during heating and mixing, resulting in lower mechanical properties. This causes poor appearance due to foam marks of deteriorated polymers and poor electrical properties due to a decrease in melt viscosity. Also, if the functional group equivalent is too much, it is not preferred because it is not grafted on carbon black and bleeds.

  Therefore, in the present invention, a silicone having a functional group equivalent of 500 g / mol or more, preferably 800 g / mol or more, more preferably 1000 g / mol or more, preferably 10,000 g / mol or less, more preferably 5000 g / mol or less. Is used.

In addition, the measuring method of the functional group of silicone is as follows.
Using a Varian Inova 500 spectrometer, in order to improve quantitativeness, chromium acetate is added as a relaxation reagent to a final concentration of 50 mM, and Si-NMR is measured. Specifically, 227.3 mg of chromium acetate is weighed and dissolved in 6.5 ml of deuterated chloroform. Further, add 1.5 ml each of the silicone sample and the deuterated chloroform solution into a 10 ml sample bottle, transfer the mixture to an NMR sample tube with an outer diameter of 10 mm, and set the temperature at 25 ° C., pulse width 30 °, and pulse repetition time 5 seconds. Then, the dimethylsiloxy main chain signal is measured as 121.00 pm as the standard of chemical shift.
Separately, NMR was measured by the above method using polydimethylsiloxane, which is most commonly used as a silicone having no functional group, and the resulting dimethylsiloxy main chain was compared with a peak to which a trimethylsilyl group was assigned. Other than the other peaks are assigned as functional group peaks, and the functional group equivalent is determined as the amount of silicone per mol of functional group.

  The average molecular weight of the silicone attached to the carbon black is preferably 100 or more and less than 100,000. When the average molecular weight of silicone is high, the functional group equivalent is relatively increased (the functional group is decreased), so that it is difficult to attach to carbon black, the grafting efficiency is lowered, and bleed out without adhesion is not preferable. Further, if the average molecular weight is a low molecular weight of less than 100, a low molecular weight siloxane gas is likely to be generated, which may cause foaming flaws during heat mixing and heat extrusion. Silicone usually exists in a chain form, but when it becomes low molecular weight, it tends to be cyclic, and when it becomes cyclic, it cannot be attached to carbon black, but it volatilizes and attaches to switch parts of electronic device parts. Since it becomes a switching defect by becoming silica (insulation) with the heat of a switch part, it is not preferred. In particular, an oligomer that volatilizes when used as a product such as a printer is not preferable because it may contaminate the photoreceptor. A more preferable average molecular weight of silicone is 1000 to 10,000.

  In addition, the average molecular weight of silicone is a weight average molecular weight in terms of polystyrene determined from a peak value in a molecular weight distribution curve measured by gel permeation chromatography.

  Moreover, the silicone used for this invention can also introduce | transduce a metal component and another polymer component partially by a graft bond or a block bond in the range which does not impair the effect of this invention remarkably. Specific examples include those having a methacrylic resin as the main chain and graft-bonding polydimethylsiloxane or the like.

Examples of silicone include dimethyl silicone, methyl hydrogen silicone, methyl phenyl silicone, amino modified silicone, alkyl modified silicone, fluorine modified silicone, polyether modified silicone, alcohol modified silicone, epoxy modified silicone, alkoxy modified silicone, carboxy modified silicone, and the like. These are preferably oil-like or gum-like and attached to carbon black.
These may be used alone or in combination of two or more.

  In order to suppress bleed of silicone, when the total of the thermoplastic polymer component composed of a thermoplastic resin and / or thermoplastic elastomer and carbon black is 100 parts by weight, the blending amount of silicone in the molding material is 0.1. It is preferable to set it as 10 to 10 weight part, and it is more preferable to set it as 0.1 to 3 weight part. If the amount of the silicone is too large, the amount of silicone that is not attached to the carbon black increases, and the silicone is poorly compatible with the thermoplastic polymer component, and therefore bleeds to the surface. On the other hand, if the amount of silicone is too small, the reduction in surface tension, which is the object of the present invention, cannot be achieved, and it does not contribute to the improvement of toner releasability and cleaning properties.

Further, if either one of the functional groups of silicone and carbon black is too much, it is not preferable because the thermoplastic polymer component deteriorates and causes foaming when the thermoplastic polymer component and carbon black are heated and mixed.
For this reason, the optimum amount of silicone to be added is determined by the type and amount of carbon black and the degree of surface tension for the desired toner releasability, and the carbon black is heated by a thermoplastic resin and / or a thermoplastic elastomer. In an endless belt containing about 10 to 50 parts by weight with respect to 100 parts by weight of the plastic polymer component, 0.1 to 10 parts of silicone is contained with respect to 100 parts by weight of the thermoplastic polymer component made of a thermoplastic resin and / or a thermoplastic elastomer. It is preferable to add parts by weight.

  In particular, the amount and type of the functional group of the silicone is determined by the type of carbon black to be mixed. For example, when the carbon black is acetylene carbon black, the thermoplastic polymer component and the acetylene carbon black total 100 parts by weight. Among them, the addition amount of silicone is 0.1 to 10 parts by weight with respect to 10 to 20 parts by weight of acetylene black, and the functional group of silicone is preferably an amino group, an epoxy group, a carboxyl group, a hydroxyl group, or the like, and a polyether. Also preferred are those modified with phenol and those having a silanol group or a silazane group. Furthermore, the functional group equivalent is preferably 500 g / mol or more and 100,000 g / mol or less.

[About carbon black]
Carbon black is mixed in consideration of mechanical characteristics, electrical characteristics, dimensional characteristics, and chemical characteristics when used as an endless belt. In the present invention, carbon black used with silicone is added before heating and mixing. In order to mix silicone with the powder, it is preferably a powder product or a granular product, and the powder is preferably uniform.

Carbon black to be used by impregnating a silicone, pH 4 or more of the following reasons, DBP oil absorption 50~300cm ³ / 100g, a specific surface area 35~500m ² / g, volatile content 0-20%, average primary particle size 20~50nm It is preferable that the carbon black satisfies the above.

-About pH of carbon black When silicone is added, if the pH of carbon black is low, the silicone is hydrolyzed, the molecular weight of the silicone is lowered, the siloxane bond that is the main chain of the silicone is decomposed, and the silanol groups are increased. For this reason, the thermoplastic polymer component and carbon black are not preferable because they decompose and generate low molecular weight siloxane gas when heated to cause foaming. Further, the silicone is hydrolyzed and bleeds without being attached to the surface of the carbon black, causing surging, and if the bleed silicone has a low molecular weight, foaming may be caused. Moreover, even if the pH is adjusted to neutrality during heating mixing or extrusion, the silanol groups produced during the dehydration condensation process, so water is generated and becomes steam in the molding machine, which is also the cause of foaming. Therefore, it is not preferable. Therefore, it is desirable to increase the pH of the carbon black before heating and mixing, and the pH is preferably 4 or more. Moreover, it is preferable that the upper limit of pH of carbon black is 12 or less.
In addition, if the pH of the carbon black is 4 or more and 10 or less, hydrolysis of the silicone is suppressed and polycondensation occurs, so that the silicone is preferably easily attached to the surface of the carbon black.
Also, when the pH of the carbon black is greater than 12, polycondensation is more likely to proceed than the hydrolysis of silicone, but there is a tendency to be hydrolyzed as compared to when the pH is 4 or more and 12 or less. It is necessary to consider.
Therefore, the pH of carbon black to which silicone is attached is preferably 4 to 10, particularly 5 to 10.
The pH of the carbon black is, for example, 10 ml of water per 1 g of carbon black in a beaker, and after boiling for 15 minutes to cool to room temperature, the supernatant is removed by a gradient method or a centrifugal method, and then the muddy state. A glass electrode pH meter electrode is inserted into the object and measured according to JIS 28802.

-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 chain-like chain (carbon structure), and the advantage that carbon aggregates are less likely to be generated. Although it is easy to express conductivity, there was an advantage of low cost, but on the other hand, the carbon chain was broken by various shearing forces applied to the resin containing carbon black in the process of compounding and molding, and the electrical resistivity was reduced. There is a problem that it tends to vary and is 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 black added for expressing conductivity is excessively increased, and there is a problem that the bending resistance of the material is impaired.
In addition, when silicone is attached before heating and mixing, the larger the DBP oil absorption amount of carbon black, the more preferable it is because the silicone can be physically adsorbed. This is not preferable because it causes deterioration of the thermoplastic polymer component during heating and mixing with the resin.
Therefore, DBP oil absorption of the preferred carbon black is 50~300cm ³ / 100g.

-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 will be expressed with a small addition weight, so the mechanical strength is advantageous in terms of resistance to cracking, but depending on the amount of carbon black added Since the conductivity tends to change abruptly, it is necessary to have a blending accuracy within ± 0.05% in order to control to the semiconductive region, and the resistance variation of the endless belt must be made uniform within ± 1 order. difficult. In addition, since carbon black with a large specific surface area generally has a small particle size, carbon black particles tend to be fooled when dispersed in a resin. As a result, carbon agglomerates are mixed in the molded product, resulting in carbon agglomerates. Electricity concentrates on the part of this area, and partial dielectric breakdown is likely to occur. In addition, 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. Resistivity tends to vary. Therefore, it is important to select an optimized carbon particle size.
In addition, in order to attach silicone, if the specific surface area of carbon black is too small, the functional groups to be attached are relatively reduced, and there is a possibility that silicone is not bonded to carbon black and bleeds. Also, if the specific surface area of carbon black is too large, unattached functional groups exist, which degrades the main thermoplastic polymer component and increases the amount of adsorbed moisture, which increases the drying time before molding. It is not preferable.
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.

-About the volatile matter of carbon black The more the volatile matter of carbon black, the better the dispersibility of carbon due to its surface characteristics, but it is 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 dispersibility 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, etc. can be suitably used. It can be used suitably. Further, carbon black subjected to a known post-treatment process such as resin-coated carbon black, heat-treated carbon black, or graphitized carbon black can be used as long as the invention is not inhibited.

  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.

  The blending amount of carbon black varies depending on the type of carbon black used and the degree of conductivity required for the endless belt, but is preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component. If it is less than this range, conductivity will not be manifested, the carbon black dispersion will be rough and the electrical resistivity will tend to vary, and the contact resistance will be greatly influenced by the environment. In some cases, an image abnormality may occur depending on the environment. On the other hand, if the amount is too large, the rigidity of the endless belt is increased, durability is impaired, and moldability is impaired.

In the present invention, the resistance value of the endless belt, that is, the content of carbon black in the molding material (hereinafter sometimes referred to as “carbon black concentration”) satisfies the following formulas (i) and (ii). This is preferable because the influence on temperature and humidity dependency 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

[Thermoplastic polymer component]
In the present invention, the thermoplastic polymer component comprises a thermoplastic elastomer and / or a thermoplastic resin.

<Thermoplastic resin>
Examples of the thermoplastic resin used in the endless belt of the present invention include polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex component such as ethylene Propylene copolymer rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymer or hydrogenated derivatives thereof, polybutadiene, polyisobutylene, polyamide (PA), polyamideimide (PAI), polyacetal (POM), polyarylate ( Par), polycarbonate (PC), polyalkylene terephthalate (PAT), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polytrimethylene terephthalate (PTT), polymethyl methacrylate (PMMA), polyphenylene oxide (PPE), polyethersulfone (PES), polymethylpentene (TPX), polyoxybenzylene (POB), polyimide ( PI), liquid crystalline polyester, polysulfone (PSF), polyphenylene sulfide (PPS), polybisamide triazole, polyamino bismaleimide, polyether imide (PEI), polyether ether ketone (PEEK), acrylic, polyfluorinated vinylidene (PVDF) ), Polyfluorinated vinyl, chlorotrifluoroethylene, ethylenetetrafluoroethylene copolymer (ETFE), hexafluoropropylene, perfluoroalkyl vinyl ether copolymer An acrylic acid alkyl ester copolymer, a polyester ester copolymer, a polyether ester copolymer, a polyether amide copolymer, a polyurethane copolymer, or the like, or a mixture of two or more thereof 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.

  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 about 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 an ester bond in the main chain and an aliphatic polyester such as polytetramethylene glycol or polycaprolactone or an alicyclic polyester such as polycyclohexadimethylene.

  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 ester bonds in the main chain, aliphatic polyesters such as polytetramethylene glycol and polycaprolactone, alicyclic polyesters such as polycyclohexadimethylene, and ester bonds such as polymethylene glycol introduced. Can be mentioned.

  There is no particular limitation on the molecular weight of the amorphous resin used in the endless belt of the present invention. 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.

(Weight ratio of thermoplastic resin to thermoplastic elastomer)
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.

(Difference in viscosity between thermoplastic resin and thermoplastic elastomer)
When an alloy material of a thermoplastic resin and a thermoplastic elastomer is used as the thermoplastic polymer component, if the difference in viscosity between the two materials is too large, good dispersion cannot be obtained even if the production conditions are adjusted. The carbon black impregnated with is also dispersed in one phase of the thermoplastic resin and the thermoplastic elastomer, and tends to be non-uniformly dispersed. Therefore, it is preferable that the viscosity difference is small. 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 measured 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 or 2 types or more of thermoplastic elastomers may be used, and these may be mixed and used. .

[Additional ingredients (optional ingredients)]
In the endless belt of the present invention, arbitrary blending components can be blended according to various purposes. However, for heat-resistant engineering plastics and the like, it is necessary to consider the heat resistance of the additional components so that they do not volatilize during heating and kneading, and there is a case where no blending is required.

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

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

[How to attach silicone to carbon black]
In order to attach silicone to carbon black, it is desirable that the surface functional group of carbon black and the functional group of silicone are chemically bonded. Therefore, depending on the type of the functional group, a certain amount of heating was performed. Is easier to combine. Further, as the method of attachment, there are a dry method such as spray coating and mixing with a mixer, and a wet method in which carbon black and silicone are dispersed and mixed in a solution and dried to skip the solution. The dry method is excellent in cost, and the wet method has a merit that it can be uniformly applied.

(About silicone adhesion to carbon black)
In order to uniformly attach the silicone to the carbon black, it is preferable to mix with stirring using a mixer having a stirring function. Further, when stirring and mixing, the heating is preferably performed at 100 ° C. or higher for 2 hours or longer. In addition to reducing the amount of solvent residue, it is possible to promote the adhesion of non-attached silicone to the carbon black surface, so that it is not decomposed during heat mixing or heat molding, which is preferable in terms of suppressing foaming and suppressing surging. More preferable heating temperature and time are, for example, 130 to 280 ° C. and 3 to 24 hours. When the heating temperature is 300 ° C. or more, the silicone is decomposed to become silica, which is not preferable.
In addition, as a mixing method, not only agitation and mixing in mixers as a dry method, but also as a wet method, silicone is diluted with various solvents, carbon black is put into the solution and mixed, and then the solvent is dried in various dryers. There is a method of removing by such as, but not limited to this.

[About heating and mixing]
In the present invention, an endless belt can be formed after heat-mixing a thermoplastic polymer component and carbon black to which silicone is added to form a resin composition, or heat-mixing the thermoplastic polymer component and carbon black to which silicone is added. And you can get an endless belt as it is.

  In this case, the kneading conditions are adjusted so that the desired surface electrical resistivity can be obtained by either heat kneading in the stage of obtaining the thermoplastic resin composition or heat kneading in the stage of molding the resin composition into an endless belt. To do. In any case, since sufficient dispersion is not possible unless it is in a molten state, it is preferable that the heating temperature be higher to some extent. Specifically, the melting point of the crystalline resin should be used as a guide, and the melting point of the crystalline resin should be exceeded. 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 thermoplastic resin composition can be heat-kneaded and then heat-treated at a melting point or lower to form an endless belt.

  Further, before the heating and mixing described above, the thermoplastic resin and the carbon black impregnated with silicone may be premixed with a mixer or the like. The thermoplastic resin can be selected from pellets, flakes, and powders. When premixing, a resin having a bulk density similar to that of carbon black to which silicone is added may be selected.

  In addition, by reducing the pressure (devolatilization) during heating and mixing, oligomers of low molecular weight substances generated by decomposition, moisture, etc. can be removed, and when used as an endless belt, foaming and poor appearance of blisters can be reduced, and Generation of surging due to bleeding can be suppressed.

  In the present invention, a specific dispersion state of the thermoplastic polymer component and the carbon black impregnated with the silicone creates a good dispersion state of the carbon black and the dispersion state of the silicone, and the toner releasability and the electric resistance value uniformity. It is considered that an endless belt excellent in both can be obtained. Therefore, since the temperature during heating and mixing and the time for receiving heat are important, it is desirable to set the heating and mixing conditions while grasping the dispersion form of the obtained endless belt. At that time, the index of the alloy state is the voltage dependency characteristic of the electrical resistivity, the variation of the electrical resistivity, and the ratio of the surface electrical resistivity and the volume electrical resistivity.

  There is no particular limitation on the heating and mixing means, and a known technique can be used. For example, if a resin composition is first prepared by heating and mixing a thermoplastic resin, carbon black to which silicone is added, and other additive components blended as necessary, a single-screw extruder, a twin-screw kneading extruder, Banbury mixers, rolls, brabenders, plastographs, kneaders and the like can be used.

  In particular, there is a technique in which a thermoplastic resin, carbon black to which silicone is added, and other additive components blended as necessary are mixed by, for example, a twin-screw kneading extruder and pelletized to form an endless belt. Preferably used.

[About molding method]
The molding method is not particularly limited, and can be obtained by employing a known method such as a continuous melt extrusion molding method, an injection molding method, a blow molding method, or an inflation molding method. This is a continuous melt extrusion method. In particular, the internal cooling mandrel method or vacuum sizing method of the downward extrusion method capable of controlling the inner diameter of the extruded tube with high accuracy is preferable, and the internal cooling mandrel method is most preferable.

  In addition, an endless belt having better physical properties can be obtained by optimizing the temperature and residence time at the time of molding. Therefore, it is preferable to adjust the conditions according to each compounding composition.

[Physical properties of endless belt]
According to the present invention, an endless belt having the following physical properties can be obtained.

-Surface tension If the surface tension of the endless belt is high, the affinity with the toner is increased and the toner tends to adhere.
If the surface tension of the endless belt is 36 dyne / cm or less, it can be used as an endless belt depending on the toner and other configurations, but is practically preferably 33 dyne / cm or less, and particularly preferably 30 dyne / cm or less. .
However, if the surface tension is too small, the friction between the photoconductor and the belt becomes too small and the primary transfer efficiency of the toner is deteriorated. Therefore, the surface tension is preferably 27 dyne / cm or more.
The surface tension of the endless belt is determined by applying various wetting reagents such as those manufactured by Wako Pure Chemicals to the belt surface using a cotton swab (approx. 6 cm ² for 0.5 seconds). Whether the standard solution closest to wetting for 2 seconds is found and the surface tension is taken as the surface tension of the sample.

<Wetting criteria>
(1) When wet: The liquid film does not break and maintains its state when applied.
(2) When not wet: Liquid film shrinks around it

・ Surface roughness Ra
The surface roughness Ra of the endless belt is preferably 0.02 μm <Ra <0.25 μm. When the surface roughness Ra is less than 0.02 μm, the primary transfer efficiency of the toner is deteriorated. If the surface roughness Ra of the endless belt is large, the cleaning performance by the cleaning blade is deteriorated and the toner slips through, which is not preferable. Therefore, the endless belt of the present invention preferably has 0.02 μm <Ra <0.25 μm, particularly preferably 0.02 μm <Ra <0.15 μm.
The surface roughness Ra of the endless belt can be measured with a non-contact confocal laser microscope such as VK8500 manufactured by Keyence. Specifically, using a lens magnification of 100 times, the surface roughness per arbitrary unit area can be measured. For example, the surface roughness in an area of 40 μm ² can be measured and the average value can be taken. .

-Bend resistance When the endless belt of the present invention is used in an image forming apparatus as an intermediate transfer belt, for example, if the flex resistance is poor, a crack occurs and an image cannot be obtained. It is preferable that As a specific numerical value, if it is 500 times or more, it can be used as an endless belt, but it is practically preferably 5000 times or more, more preferably 10,000 times or more, more preferably 30000 times or more. If it is, it will become difficult to generate | occur | produce a crack especially, and it is especially preferable.
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.

-Tensile elastic modulus If the endless belt has a low tensile elastic modulus, for example, when it is used as an intermediate transfer belt in an image forming apparatus, it may cause a slight elongation due to tension, which may cause problems such as color misregistration. Is higher, specifically 1000 MPa or more, more preferably 1500 MPa or more, more preferably 2000 MPa or more, and particularly 2500 MPa or more, since problems such as color misregistration can be significantly suppressed. preferable.
In general, a soft plastic has a high folding resistance but tends to have a low tensile elastic modulus. Conversely, a hard plastic can obtain a high tensile elastic modulus but tends to become brittle and often has only a low folding resistance. In this invention, it can be said that it is useful in the meaning which can obtain a high frequency | count of folding-proof, maintaining the characteristic of the inherent high tensile elasticity modulus which PBT and PC have.

-Surface resistivity The endless belt of this invention can obtain electroconductivity by mix | blending carbon black.
The resistance region varies depending on the purpose, but is preferably selected from the range of surface resistivity of 1 to 1 × 10 ¹⁶ Ω / □.

Further, the preferred range varies depending on the application. For example, when used as a photoreceptor belt, a low surface resistivity of 1 to 1 × 10 ⁹ Ω / □ is preferable so that the charge on the outer surface can be released to the inner surface as necessary. When used as an intermediate transfer belt, 1 × 10 ⁶ to 1 × 10 ¹³ Ω / □, which can be easily charged and transferred, is preferable, and when used as a transfer transfer belt, it is easily charged and is not easily damaged even at a high voltage. A high region of 10 ¹⁰ to 1 × 10 ¹⁶ Ω / □ is preferable.
Further, it is preferable that the distribution of the surface resistivity in one endless belt is narrow, and in each preferable surface resistivity region, the difference between the maximum value and the minimum value in one is preferably within one digit.
The surface 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 Co., Ltd.

-Thickness of endless belt The thickness of the endless belt is preferably 50 to 1000 µm, more preferably 80 to 500 µm, and particularly preferably 100 to 200 µm.

[Application of endless belt]
The endless belt of the present invention is used in an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, and a facsimile machine as an intermediate transfer belt, a transfer transfer belt, a photosensitive belt, and the like. The endless belt may be used as it is, or may be wound around a drum or a roll.
Furthermore, for the purpose of preventing meandering or reinforcing the end face, heat resistant tape is applied to the inside and / or the vicinity of the outside end of the endless belt of a predetermined size, or a tape such as urethane rubber or silicone rubber is attached to the inside edge of the belt. You may affix on the part vicinity.

The effects of the present invention will be described below with reference to examples and comparative examples.
<material>
The raw materials were as follows, and the mixing ratio was as shown in Table 1.

(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: “Iupilon 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)
・ Carbon black 1: Acetylene black "Denka black granular product" manufactured by Electrochemical Co., Ltd.
pH = 9
DBP oil absorption = 180ml / 100g
Specific surface area = 65 m ² / g
Volatile content = 0%
Average primary particle size = 39 nm
・ Carbon black 2: Channel black "Printex140V" manufactured by Degussa
pH = 4.5
DBP oil absorption = 110ml / 100g
Specific surface area = 90 m ² / g
Volatile content = 5%
Average primary particle size = 29 nm
Carbon black 3: Furnace black “MA100” manufactured by Mitsubishi Chemical Corporation
pH = 3
DBP oil absorption = 100ml / 100g
Specific surface area = 110 m ² / g
Volatile content = 1.5%
Average primary particle size = 24 nm

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

(silicone)
・ Silicone 1: Silicone oil “SH200” manufactured by Toray Dow Corning Co., Ltd.
Functional group equivalent = impossible to measure because there is no functional group
Average molecular weight = 4400
・ Silicone 2: Side chain type amino-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.
"KF-865"
Functional group equivalent = 1200 g / mol
Type of functional group = amino group
Average molecular weight = 5500
・ Silicone 3: Terminal-type amino-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.
"KF-8012"
Functional group equivalent = 1700 g / mol
Type of functional group = amino group
Average molecular weight = 4300
Silicone 4: Alcohol-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.
"KPN-3504"
Functional group equivalent = 2900 g / mol
Type of functional group = hydroxyl group
Average molecular weight = 2900
Silicone 5: Silicone-containing masterbatch manufactured by Toray Dow Corning Co., Ltd.
"BY27-009"
Functional group equivalent = impossible to measure because there is no functional group
Average molecular weight = 500 × 10 ³
(Contains 50% ultra high molecular weight silicone with respect to the base polymer PBT)
・ Silicone 6: Terminal-type amino-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.
"KF-8010"
Functional group equivalent = 430 g / mol
Type of functional group = amino group
Average molecular weight = 860

<Combination>
In each example and comparative example, the blends of polybutylene terephthalate (PBT), thermoplastic elastomer (TPE), carbon black (CB), and antioxidant other than silicone were made two depending on the carbon black concentration. A total of 100 parts by weight of the thermoplastic polymer component and carbon black were blended, and the antioxidant and silicone were externally added. Further, the carbon black concentration was set for each type of carbon black with a target range of an approximate resistance value as a target, and PBT and TPE were blended in a ratio of 7 to 3. The types and amounts of silicone are shown in Tables 1 and 2 for each example and comparative example.

(Weight mixing ratio common to each example)
Carbon black concentration: 13.5% by weight (corresponding to Examples 1 to 12 and Comparative Examples 1 to 4)
PBT: 60.55 parts by weight TPE: 25.95 parts by weight CB: 13.50 parts by weight Antioxidant: 0.30 parts by weight Silicone: parts by weight shown in Tables 1 and 2 • Carbon black concentration of 17.5% by weight Case (corresponding to Example 13 and Comparative Example 5)
PBT: 57.75 parts by weight TPE: 24.35 parts by weight CB: 17.50 parts by weight Antioxidant: 0.30 parts by weight Silicone: parts by weight shown in Tables 1 and 2

(Adhesion of silicone to carbon black)
1 kg of carbon black was charged into a Kubota weight feeder (CE-S-4), and each silicone was charged at 20 g / min while rotating the agitator at 10 rpm. After completion of the charging, the mixture was stirred and mixed for 5 minutes under the same conditions. At this time, heating was not performed. For example, when blended with 1 part by weight of silicone and 13.5 parts by weight of carbon black, 7.4% of carbon black is blended (74.07 g is added to 1 kg of carbon black), and the thermoplastic polymer as a whole A total of 100 parts by weight of carbon black was adjusted to 1 part by weight of silicone.

<Heat kneading>
Each raw material was pelletized using a twin-screw kneading extruder (PMG32 manufactured by IKG Co., Ltd.).
The extruder has L / D = 32, 2 vent type, kneading is arranged on the raw material charging side from each vent, the raw material charging side vent is only opened, and the molten resin discharge side is -760 mmHg ( The pressure was reduced to -100 kPa). The resin discharge rate is 14 kg / h, the cylinder temperature is 250 ° C. from the cylinder closest to the hopper to the cylinder with the vent on the raw material input side, the other is 200 ° C., and the rotation speed is 140 rpm. The discharged molten resin was made into a strand shape and passed through a water tank, and then pelletized to produce pellets of a predetermined size.

<Endless belt molding method>
The material pellets obtained by heating and kneading are dried at 130 ° C. for 12 hours, extruded in a molten tube state below the annular die by a 40 mmφ extruder with a six-spiral annular die having a diameter of 190 mm and a die slip width of 1.0 mm. The molten tube was placed in the endless belt while contacting the outer surface (temperature 90 ° C) of a cooling mandrel with an outer diameter of 184 mm mounted on the same axis as the annular die via a support rod and cooling and solidifying it. The cylindrical core and the 4-point type belt take-up machine installed on the outside are used to hold the endless belt in a cylindrical shape, and it is cut into a length of 300 mm, with a thickness of 140 μm, surface While adjusting the extrusion amount, the take-off speed, and the extrusion temperature so that the resistance value becomes 1 × 10 ⁷ to 1 × 10 ¹² Ω, The temperature of the chair was 260 ° C., and an endless belt having an inner diameter of 183 mm and a thickness of 0.14 mm was used.

<Evaluation method>
The evaluation was carried out by cutting the endless belt to the required size as required.

・ Surface resistance value Ω / □
A sample with a surface resistivity of 10 ⁶ to 1 × 10 ¹³ Ω / □ uses a Hiresta (HA terminal) manufactured by Dia Instruments Co., Ltd., and the belt circumferential direction is 20 mm pitch at 100 V for 10 seconds. And the average value of the obtained surface resistivity was defined as the surface resistance value.

・ Surface tension As for surface tension, apply various wetting reagents such as those manufactured by Wako Pure Chemical on the belt surface using a cotton swab (approx. 6 cm ² for 0.5 seconds). The standard solution closest to wetting for 2 seconds was found, and the surface tension was taken as the surface tension of the sample.
(Wetting criteria)
When wet: The liquid film does not break and maintains the state when applied. When not wet: The liquid film shrinks around it.

・ Surface roughness The outer surface of the endless belt is cut into a sample of about 50 mm × 50 mm, and a VK8500 (non-contact confocal laser microscope) manufactured by Keyence Corporation is used to measure the lens magnification 100 times, the pitch 0.01 μm, and the AUTO measurement. The average value when the surface roughness of an area of 40 μm × 40 μm was measured four times in the mode was taken as the measured value of the surface roughness.

-Formability Evaluated according to the following criteria.
◎: No problem ○: Slightly surging △: Surging ×: Remarkable surging

-Presence / absence of foaming Evaluation was made according to the following criteria.
○: No foaming △: Slight foaming ×: Foaming

<Evaluation results>
The evaluation results are shown in Tables 1 and 2.

<Discussion>
From Tables 1 and 2, the following can be understood.

(Examples 1-3)
The silicone used was KF-865 (functional group equivalent 1200 g / mol, molecular weight 5500) manufactured by Shin-Etsu Chemical Co., Ltd., and the carbon black used was Denka Black granular product manufactured by Electrochemical. When the amount of silicone added was changed to 0.25, 0.5, and 1.0 parts by weight, no foaming or surging was observed in any amount. Further, the surface tension was reduced at any addition amount, and the degree of surface tension reduction was proportional to the increase in the addition amount.

(Examples 4 to 6)
Silicone used was KF-8012 (functional group equivalent: 1700 g / mol, molecular weight: 4300) manufactured by Shin-Etsu Chemical Co., Ltd., and Denka Black granular product manufactured by Electrochemical was used as the carbon black. When the amount of silicone added was changed to 0.25, 0.5, and 1.0 parts by weight, no foaming or surging was observed in any amount. Further, the surface tension was reduced at any addition amount, and the degree of surface tension reduction was proportional to the increase in the addition amount.

(Examples 7 to 9)
As the silicone, KPN-3504 (functional group equivalent 2900 g / mol, molecular weight 2900) manufactured by Shin-Etsu Chemical Co., Ltd. was used, and Denka Black granular product manufactured by Electrochemical was used as the carbon black. When the addition amount of silicone was changed to 0.20, 0.5, and 1.0 parts by weight, surging was not observed in any compounding amount. Foaming was slightly confirmed only when the addition amount was 1.0 part by weight, but the surface roughness was not deteriorated. Further, the surface tension was reduced at any addition amount, and the degree of surface tension reduction was proportional to the increase in the addition amount.

(Examples 10 to 12)
As the silicone, SH200 (no functional group, molecular weight 4400) manufactured by Toray Dow Silicone was used, and Denka Black granular product manufactured by Electrochemical was used as the carbon black. When the addition amount of silicone was changed to 0.25, 0.5 and 1.0 parts by weight, no surging was observed at 0.25 parts by weight, but surging was observed at 0.5 and 1.0 parts by weight. It was observed. Foaming was slightly confirmed only when the addition amount was 1.0 part by weight, and the surface roughness was slightly deteriorated. Further, the surface tension was reduced at any addition amount, and the degree of surface tension reduction was proportional to the increase in the addition amount.

(Example 13)
As the silicone, KPN-3504 (functional group equivalent: 2900 g / mol, molecular weight: 2900) manufactured by Shin-Etsu Chemical Co., Ltd. was used, and Printex 140V manufactured by Degussa was used as the carbon black. When the amount of silicone added was 1.0 parts by weight, the surface tension decreased to 30 dyne / cm or less. Although the foaming was observed, surging or the like did not occur.

(Comparative Example 1)
Silicone was not added. Although surging and foaming were not confirmed, the surface tension was 36 dyne / cm.

(Comparative Examples 2-3)
As silicone, BY27-009 manufactured by Toray Dow Silicone (no functional group, molecular weight of 500 × 10 ³ or more) was added as a PBT-based masterbatch (silicone content 50% by weight). The carbon black used was Denka Black granular product made by Electrochemical. When the addition amount of silicone was changed to 1.0 and 2.0 parts by weight, remarkable surging was observed at any addition amount. This is presumably due to the fact that the bleed was remarkable due to the ultrahigh molecular weight of silicone. Foaming was not confirmed. In addition, the surface tension decreased at any addition amount.

(Comparative Example 4)
As the silicone, KF-8010 (functional group equivalent: 430 g / mol, molecular weight: 860) manufactured by Shin-Etsu Chemical Co., Ltd. was used, and Denka Black granular product manufactured by Electrochemical was used as the carbon black. When the amount of silicone added was 0.5 parts by weight, no surging was observed, but foaming was confirmed. This is presumably because the unreacted functional group promoted polymer deterioration because of the large amount of functional groups. The surface tension decreased to 30 dyne / cm or less.

(Comparative Example 5)
As the silicone, KPN-3504 (functional group equivalent 2900 g / mol, molecular weight 2900) manufactured by Shin-Etsu Chemical Co., Ltd. was used, and MA100 manufactured by Mitsubishi Chemical was used as the carbon black. When the amount of silicone added was 1.0 parts by weight, the surface tension was reduced to 30 dyne / cm or less, but foaming and blistering occurred, and surging also occurred.

  From the above results, it is possible to provide a seamless belt for an image forming apparatus with high image quality and high durability by preliminarily blending a silicone oil having a predetermined functional group equivalent with carbon black having a pH of 4 or higher. I understand.

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 (10)

An endless belt used in an image forming apparatus, the main component of which is a thermoplastic polymer component made of a thermoplastic resin and / or a thermoplastic elastomer, and the thermoplastic polymer component and carbon black are mixed by heating and extruded. In the obtained endless belt for an image forming apparatus,
The pH of the carbon black is 4 or more, prior to the heat mixing of the thermoplastic polymer component and the carbon black, silicone is attached to the carbon black, and the functional group equivalent of the silicone is 500 g / mol or more. An endless belt for an image forming apparatus.   2. The endless belt for an image forming apparatus according to claim 1, wherein the thermoplastic polymer component has an ester bond.   3. The endless belt for an image forming apparatus according to claim 1, wherein the average molecular weight of the silicone is 100 or more and less than 100,000.   In any 1 item | term of Claim 1 thru | or 3, content of this silicone is 0.1 with respect to a total of 100 weight part of the thermoplastic polymer component which consists of a thermoplastic resin and / or a thermoplastic elastomer, and carbon black. An endless belt for an image forming apparatus, wherein the endless belt is 10 to 10 parts by weight. In any one of claims 1 to 4, wherein the carbon black, DBP oil absorption 50~300cm ³ / 100g, a specific surface area 35~500m ² / g, volatile content 0-20%, average primary particle size 20~50nm An endless belt for an image forming apparatus, characterized in that:   6. The endless belt for an image forming apparatus according to claim 1, wherein the carbon black is acetylene black.   7. The endless belt for an image forming apparatus according to claim 1, wherein the surface roughness Ra is 0.02 [mu] m <Ra <0.25 [mu] m.   8. The endless image forming apparatus according to claim 1, wherein the material to be extruded has a melt viscosity indicated by a melt flow rate (MFR) of 0.1 g / 10 min or more. belt.   9. The endless belt for an image forming apparatus according to any one of claims 1 to 8, wherein the thermoplastic polymer component includes polyalkylene terephthalate.   An image forming apparatus comprising the endless belt for an image forming apparatus according to claim 1.

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