JP2017126017A - Resin belt and method for manufacturing the same, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin belt that is excellent in properties including mechanical property, electrical property, fire retardancy, surface glossiness (surface smoothness), durability, image forming property, filming property, resistance controllability, molding stability, and handleability.SOLUTION: There is provided a resin belt containing polyimide and carbon black, the resin belt having: a heat of fusion of 15 mJ/mg or more and 25 mJ/mg or less detected in a temperature range of 250°C or more and 350°C or less; the carbon black in a blending amount of 5-20 parts by mass based on 100 parts by mass of the polyimide; an average thickness of 40-120 μm; a Martens hardness of 120 N/mmor more and 280 N/mmor less; and an elastic modulus in tension of 1500 MPa or more and 2500 MPa or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin belt, a manufacturing method thereof, and an image forming apparatus.

An intermediate transfer belt used in an electrophotographic apparatus or the like is required to have electric resistance uniformity, surface smoothness, mechanical properties (high bending, high elasticity, high elongation), and high dimensional accuracy (film thickness, circumference). Recently, flame retardancy at the component level is also required, and UL94 VTM-1 or higher, and VTM-0 or higher may be required particularly for models of medium and high speed machines or higher. In addition, functionality when used as a belt is also required, and transfer properties, abnormal images, stability of the surface state of the belt by passing paper, and the like are required.
As a material satisfying the above required characteristics, a two-layer belt is used in which a varnish into which fluorine or siloxane is introduced is coated on a material obtained by imparting conductivity to a thermosetting polyimide resin or polyamide-imide resin. .

As a technology for producing a heat-resistant endless belt from a polyimide resin, a polyimide varnish is cast-molded on the outer peripheral surface of a cylindrical body made of metal, and then this cast-molded polyimide varnish is heated and imidized to imitate the polyimide endless Techniques for belts have been proposed. However, this technique has the problem that the material cost is high and the imidization process takes time and the production cost is also high. In addition, since a new mold is required every time the dimensional standard is changed, a large number of molds are required, which causes a problem that the initial cost increases.
In addition, in order to make a two-layer belt, it is necessary to coat the varnish with fluorine or siloxane introduced by spraying or blade coating (thickness 0.5 to 10 μm), which increases the number of processing steps and further increases costs. There are drawbacks.

The intermediate transfer belt is an expensive part of the electrophotographic apparatus, and there is a strong demand for cost reduction. In order to reduce the cost, if a thermoplastic resin is used and it can be molded by extrusion molding or inflation molding, it can be manufactured at a very low cost.
Examples of the flame retardant thermoplastic resin include fluorine resins such as PVDF (polyvinylidene fluoride), polyarylate resin, PPS (polyphenylene sulfide) resin, PES (polyethersulfone) resin, PS (polysulfone) resin, PEI (polyethylene). Etherimide) resin, PEEK (polyetheretherketone) resin, TPI (thermoplastic polyimide), LCP (liquid crystal polymer), etc. have been proposed. Both the later-described transfer belt functionality (transfer rate and sheet feeding stability) cannot be satisfied.

  As a conductive seamless belt using a flame-retardant thermoplastic resin, a semiconductive film in which polyether ether ketone (PEEK) and a conductive filler are blended in Patent Document 1 (Japanese Patent Laid-Open No. 2005-112942) is used. Although it has been proposed, the film of PEEK alone satisfies the mechanical properties, but the resin cost is very high, so it cannot satisfy the currently required cost reduction.

In addition, as a conductive seamless belt using a flame-retardant thermoplastic resin, acetylene black is used in a semiconductive film in which polyether ether ketone and acetylene black are blended in Patent Document 2 (Japanese Patent Laid-Open No. 2012-133220). Has been proposed in which 19% by weight or more and 30% by weight or less is blended with respect to the thermoplastic resin, and the particle number density of acetylene black observed in the film cross section is 20 particles / μm ² or more. Certainly, when a large amount of low-conductivity carbon is blended, the voltage dependency is improved, but the mechanical properties and gloss of the film are lowered.

  In addition, as a conductive seamless belt using a flame-retardant thermoplastic resin, polyphenylene sulfide and a conductive filler are blended in Patent Document 3 (Japanese Patent Laid-Open No. 2006-69046), and the heat of fusion by DSC is 10 mJ /. A semiconductive film of mg or more has been proposed, but polyphenylene sulfide is liable to generate foreign matters due to aggregation of conductive carbon or unmelted polymer during film formation, and filming may occur when used as a belt. There is a problem that occurs.

  Patent Document 4 (Japanese Patent Laid-Open No. 2000-137389) proposes an endless belt-shaped transfer member made of a polyarylate resin, but there is a problem that an amorphous material is inferior in bending resistance.

Patent Document 5 (Japanese Patent Laid-Open No. 2001-125396) proposes a transfer belt made of a non-thermoplastic polyimide resin or a thermoplastic polyimide resin.

  Patent Document 6 (Japanese Patent Application Laid-Open No. 2008-15491) proposes a single-layer intermediate transfer belt made of a crystalline thermoplastic resin, but a crystallization exothermic peak is detected by a differential scanning calorimeter (DSC). The crystallinity is insufficient, so that sufficient hardness cannot be achieved. In addition, when used as a belt, there is a problem that scratches occur on the back surface due to contact with the stretching roller.

  The present invention is excellent in various properties such as mechanical properties, electrical properties, flame retardancy, surface glossiness (surface smoothness), durability, image forming properties, filming properties, resistance controllability, molding stability and handling properties. An object of the present invention is to provide a resin belt.

The above problem is solved by the configuration 1) below.
1) A resin belt containing at least polyimide and carbon black,
The resin belt is one in which a heat of fusion of 15 mJ / mg to 25 mJ / mg is detected in a temperature range of 250 ° C. to 350 ° C. by thermal analysis using a differential scanning calorimeter,
The compounding amount of the carbon black with respect to 100 parts by mass of the polyimide is 5 to 20 parts by mass,
The resin belt has an average thickness of 40 to 120 μm,
Said resin belt Martens hardness is at 120 N / mm ² or more 280N / mm ² or less, and the resin belt modulus measured in tensile properties test method specified in JIS K7127 is less than 2500MPa or more 1500MPa Solved by the characteristic resin belt.

  According to the present invention, various properties such as mechanical properties, electrical properties, flame retardancy, surface glossiness (surface smoothness), durability, image forming properties, filming properties, resistance controllability, molding stability and handling properties, etc. An excellent resin belt is provided.

It is a figure of an example of the DSC curve of the polyimide used by this invention. It is a figure which shows the relationship between generation | occurrence | production of the back surface crack of a belt, Martens hardness, and a tensile elasticity modulus. It is a figure which shows the cyclic | annular die which consists of the die | dye used when extruding the resin belt of this invention, and a mandrel. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 5 is a schematic cross-sectional view illustrating an example of a configuration of an image forming unit in which a photoreceptor is disposed in the image forming apparatus of FIG. 4.

An embodiment of the resin belt of the present invention includes a conductive resin belt, and this embodiment will be described below.
First, a first embodiment of the conductive resin belt of the present invention will be described.
The conductive resin belt of the present invention contains polyimide, preferably thermoplastic polyimide (hereinafter abbreviated as TPI) and carbon black (hereinafter abbreviated as CB), and is 250 ° C. or higher and 350 or higher by thermal analysis using a differential scanning calorimeter. A heat of fusion of 15 mJ / mg or more and 25 mJ / mg or less is detected in a temperature range of 0 ° C. or less. Further, the sum is 5 to 20 parts by weight of the amount of CB respect TPI100 parts by mass average thickness is molded to 40 to 120, Martens hardness is at 120 N / mm ² or more 280N / mm ² or less, and The elastic modulus measured by the tensile property test method defined in JIS K7127 is 1500 MPa or more and 2500 MPa or less.

The TPI used in the present invention is a compound having an imide group in the molecule as shown in the following formula, and is distinguished from a polyetherimide (PEI) having an imide group. The characteristics such as crystallinity / amorphity, melting point Tm, glass transition temperature Tg, etc. are greatly different depending on the selection of the functional group entering R ₁ , R ₂ or X and the number n of repetitions.

In the above formula, R ₁ and R ₂ are each independently a functional group containing an aromatic ring or alicyclic hydrocarbon, and X is a functional group containing an aromatic ring. A preferred TPI in the present invention is an alicyclic compound in which R ₁ has 6 to 22 carbon atoms and contains nitrogen. Preferred R ₂ is a chain aliphatic compound containing nitrogen having 5 to 12 carbon atoms. Preferred X is an aromatic compound containing nitrogen having 6 to 22 carbon atoms. Preferred n is 5 to 70.

  Generally, TPI includes crystalline TPI and amorphous TPI. In the present invention, crystalline TPI is used. In the present invention, a TPI that detects the heat of fusion can be appropriately selected from known TPIs.

As described above, in the conductive resin belt of the present invention, a heat of fusion of 15 mJ / mg to 25 mJ / mg is detected in a temperature range of 250 ° C. to 350 ° C. by thermal analysis using a differential scanning calorimeter.
The TPI used in the present invention is preferably one in which a heat of fusion of 15 mJ / mg to 35 mJ / mg is detected in a temperature range of 250 ° C. to 350 ° C. by thermal analysis using a differential scanning calorimeter.
The lower limit of the heat of fusion of TPI is preferably 18 mJ / mg, more preferably 20 mJ / mg, and the upper limit of the heat of fusion is preferably 30 mJ / mg, more preferably 25 mJ / mg.

The heat of fusion in the present invention can be measured by a known method. For example, X-DSC7000 (manufactured by Shimadzu Corporation) is used, and the measurement conditions are a heating rate of 10 ° C./min and a sample amount of 5 mg. can do. The sample is cut so that the conductive resin belt enters the aluminum pan for measurement, and when the cut sample is less than 5 mg, a plurality of samples are used.
FIG. 1 is a diagram showing an example of a DSC curve of TPI used in the present invention. In FIG. 1, Tg represents the glass transition temperature, Tm represents the melting point, and the peak area of the melting point represents the heat of fusion.
As a result of intensive studies, the inventor's melting heat, which is the area of the melting point peak, is one characteristic value for measuring the crystallinity of the material. It will be. In addition, when the heat of fusion increases, the bending resistance is improved.

  In the conductive resin belt of the present invention, another crystalline thermoplastic resin may be added at a ratio of 20 parts by mass or less with respect to 100 parts by mass of TPI in order to improve hardness and flex resistance. Sulfide) resin and PEEK (polyether ether ketone) resin are preferred.

  As TPI, a high melting point material having a molding temperature of about 400 ° C. and a low melting point material of 300 to 360 ° C. are known. Any material may be used in the present invention, but the latter material is preferred. The reason is that when TPI is a low melting point material, it is possible to produce the conductive resin belt of the present invention using general equipment, while TPI is a high melting point material. This is because special equipment is required, and the equipment cost is enormous. Moreover, if TPI is a low melting point material, since it is a molding process temperature comparable as PPS and PEEK, alloying with these resin is attained.

  The TPI used in the present invention can satisfy the Martens hardness and tensile elastic modulus defined in the present invention, and is particularly excellent in flex resistance and surface smoothness (gloss). As a result, it solves image defects such as cracks, breaks, scratches, filming (gloss change due to paper passing), white spots, stickiness, and vomits when running on the belt. It is easy to obtain, can realize low-cost production, and can meet high-level voltage dependency requirements.

  The conductive resin belt of the present invention contains carbon black, and the amount thereof is 5 to 20 parts by mass with respect to 100 parts by mass of the TPI.

Examples of the conductivity imparting material generally include a conductive filler, and the conductive filler is divided into a metal system, a metal oxide system, a metal coating system, and a carbon system. Metal systems (Ag, Ni, Cu, Zn, Al, stainless steel, etc.) have the highest conductivity and are not suitable for high resistance. In addition, other than expensive Au and Ag, there is a problem that the resistance value changes easily because it is easily oxidized. In order to obtain a conductive with the metal oxide of _{(SnO 2, In 2 O 3} , ZnO) , it is necessary to blend 10 to 50 parts by weight relative to the total of the resin, decreases the mechanical properties of the polymer There is a case. Moreover, it is a high cost material and is not suitable as a conductive agent of the present invention. Carbon system is inexpensive and can control medium to high resistance range. In addition to the conductive filler, an ionic material is known as a conductivity imparting material. However, the method using an ionic conductivity has a problem of bleeding out on the belt surface.
Carbon black is suitable as a conductivity imparting agent because it is relatively inexpensive and hardly subject to environmental dependence. Carbon black includes furnace black, channel black, acetylene black, ketjen black, and the like depending on the production method, and any type can be used in the present invention. The carbon black used in the present invention preferably has a volatilization (weight loss) content of 2.0% by mass or less when heated at 950 ° C. for 7 minutes. Such carbon black is difficult to foam when a high molding temperature is adopted.

  In this invention, the more preferable compounding quantity of carbon black is 9-18 mass parts with respect to 100 mass parts of said TPI. In general, the resistance value decreases as the blending amount of carbon black is increased. However, the amount added to obtain the target resistance value depends on the type of carbon black (particularly DBP (dibutyl phthalate) absorption (JIS K6221). )).

  Moreover, the average thickness of the conductive resin belt of this invention is 40-120 micrometers. A thicker average thickness is advantageous for flame retardancy, but the bending resistance is lowered. On the other hand, if the average thickness is less than 40 μm, the durability will be improved, but the end strength will be reduced, so that it will be unstable when used as a transfer belt, and kinks will easily occur during handling. There is a problem. From these viewpoints, the average thickness of the conductive resin belt of the present invention is preferably 60 to 80 μm. For the measurement of the average thickness, a contact-type digimatic micrometer MDC25S (manufactured by Mitutoyo) is used, and 10 points are randomly measured in the circumferential direction of the belt, and are obtained by arithmetic average.

Moreover, Martens hardness of the conductive resin belt of the present invention is 120 N / mm ² or more 280N / mm ² or less, and modulus measured in tensile properties test method specified in JIS K7127 is not more than 2500MPa or more 1500MPa .
When the Martens hardness of the conductive resin belt is lower than 120 N / mm ² , the back surface is liable to be damaged due to contact with the stretching roller when used as a transfer belt, and fine paper dust is formed on the transfer belt surface. Filming (gloss change due to paper passing) occurs due to the adhesion. When the Martens hardness of the conductive resin belt is higher than 280 N / mm ² , the belt becomes rigid and the bending resistance is lowered, which is not preferable.
In the present invention, the Martens hardness of the conductive resin belt, and even more preferably 180 N / mm ² or more 220 N / mm ² or less.
The Martens hardness is measured by using a microhardness meter HM2000LT (manufactured by Fischer), controlling the load, and increasing the load 5 mN / 10 s (decrease is the same condition) and creep 10 s.
Further, the elastic modulus of the conductive resin belt affects the generation of scratches. For example, when the belts have the same Martens hardness, the lower the tensile elastic modulus, the more the generation of scratches can be suppressed. On the other hand, if the tensile elastic modulus is too low, the belt circumference changes over time when stretched on a roller, and color misregistration decreases. As a result of intensive studies, the present inventor has found that the Martens hardness and tensile elastic modulus of the conductive resin belt need to be set within a specific range in order to achieve the effects of the present invention. FIG. 2 is a diagram showing, as an example, the relationship between the occurrence of scratches on the back surface of the belt, the Martens hardness, and the tensile elastic modulus. By setting the Martens hardness and the tensile elastic modulus of the conductive resin belt within the hatched range in FIG. 2, the occurrence of scratches on the back surface can be suppressed. In addition, other effects of the present invention are further enhanced by the range. That is, the elastic modulus of the conductive resin belt of the present invention is required to be 1500 MPa or more and 2500 MPa or less, and more preferably 1800 MPa or more and 2200 MPa or less.

The conductive resin belt of this embodiment has mechanical characteristics, electrical characteristics, flame retardancy, surface glossiness (surface smoothness), durability, image formability, filming property, resistance controllability, molding stability, and handleability. Although it is excellent in various properties such as, the effects to be noted are as follows.
(1) In spite of the single-layer conductive resin belt, it has excellent Martens hardness, tensile elastic modulus, and bending resistance, so that it is possible to prevent the occurrence of cracks, breaks, scratches and filming during belt running.
(2) Excellent flame retardancy (VTM-1).
(3) Reproducibility of characteristics is easy and manufacturing reproducibility is easily obtained.
(4) The material cost is low, and low-cost production is possible compared to thermosetting polyimide (PI) or PEEK.
(5) A high level voltage dependency requirement can also be met.

  Next, a second embodiment of the conductive resin belt of the present invention will be described below. In the present embodiment, in the conductive resin belt of the first embodiment, the number of reciprocal bendings (MIT value) measured in the folding strength test method defined in JIS P 8115 is 2000 times or more and 20000 times or less. It is characterized by being.

  When the MIT value is less than 2000 times, cracks and fractures occur in the belt durability evaluation of 240 kp (printing of 24,000 sheets of recording medium) or less, but if the MIT value is 2000 times or more, cracks and breaks occur. It was found that no breakage occurred. On the other hand, when the MIT value is 20000 times or less, it is within an appropriate hardness range, which is advantageous in terms of preventing cracks, fractures, scratches, and filming.

A third embodiment of the conductive resin belt of the present invention will be described below.
This embodiment, in the first and / or second embodiment, consists of two or more, including at least DBP absorption 200 cm ^3/100 g or more of the carbon black and one 100 cm ^3/100 g and one less carbon black The carbon black content is 18 parts by mass or less with respect to 100 parts by mass of TPI. The amount of carbon black in the belt can be quantified based on the method of JIS K6227.

  The voltage dependence of the electrical resistance is caused by the difference in the conductive path depending on the voltage. In the present invention, the CB dispersion uniformity is affected. In order to improve the dispersion uniformity, it is preferable to disperse more particles and reduce the difference in the distance between the conductive paths. Therefore, furnace black and acetylene black having a relatively small DBP absorption amount are generally used. ing. However, the smaller the amount of CB, the more advantageous in mechanical properties and gloss. When the blending amount of carbon black increases, mechanical properties, glossiness, and surface smoothness (the main cause of filming) decrease. In particular, the bending resistance is greatly reduced. Among carbon blacks, ketjen black has a large DBP absorption amount, so it is a suitable material that can achieve the target resistance with a small amount, but it has poor voltage dependency on electrical characteristics and has problems with reproducibility. There is little to do. According to the third embodiment of the present invention, by blending two or more types of carbons having different DBP absorption amounts, it is possible to achieve the required electrical characteristics while suppressing the carbon blending amount to a small amount.

The conductive resin belt of the third embodiment has the following effects in addition to the effects of the conductive resin belts of the first and / or second embodiments.
(1) Ketjen black that produces resistance in a small amount can be used.
(2) By setting the above two or more types of CB to 18 parts by mass or less with respect to 100 parts by mass of the TPI, it is possible to prevent a decrease in glossiness and achieve a target gloss.
(3) By setting the above two or more types of CB to 18 parts by mass or less with respect to 100 parts by mass of the TPI, it is possible to suppress a decrease in mechanical properties such as bending resistance and achieve the target characteristics.

In DBP absorption 200 cm ^3/100 g or more CB, more preferably the DBP absorption of the range ^is less 240 cm 3/100 g or more 300 cm ^3/100 g.
In DBP absorption 100 cm ^3/100 g or less of CB, more preferably the DBP absorption of the range ^is less 85cm 3/100 g or more 96cm ³ / 100g.
The mixing ratio of the DBP absorption 200 cm ^3/100 g or more CB and DBP absorption 100 cm ^3/100 g or less of CB, the former: the latter (weight ratio), 8: 1 to 1: 1.

Next, a fourth embodiment of the conductive resin belt of the present invention will be described.
In the present embodiment, the volume resistivity (Rv100 [Ω · cm]) at 100 V of the conductive resin belt is 10 ⁸ to 10 ¹² [Ω · cm] in the first, second and / or third embodiments. The surface resistivity (Rs500 [Ω]) at 500 V of the conductive resin belt is 10 ⁸ to 10 ¹² [Ω].
By satisfying the volume resistivity and surface resistivity as described above, the image quality can be further enhanced.

Next, the manufacturing method of the conductive resin belt of this invention is demonstrated below.
This production method is a method for producing the conductive resin belt of the first, second, third and / or fourth embodiment, wherein the TPI particles and CB are stirred at a high speed at 1000 to 3000 rpm. And a step of melt-kneading the mixture obtained by stirring at 300 to 370 ° C. to obtain a melt-kneaded product, and a molding step of extruding the melt-kneaded product from a die and molding it to obtain a molded product. It is characterized by. When the rotational speed in the high-speed stirring is out of the above range, more specifically, when the rotational speed is less than 1000 rpm, the CB dispersion failure is more than 3000 rpm. Further, when the melt kneading temperature is outside the above range, more specifically, when the melting point of the TPI to be used is lower than the melting point of the TPI to be used, if the conveyance failure of the mixture is higher than the decomposition temperature of the TPI to be used, As a result, there is a risk of appearance defects such as silver streaks occurring on the belt surface. The means for stirring at high speed, the means for melting and kneading, and the means for extrusion molding can be appropriately selected from known means. By adopting such a production method, particularly before kneading, TPI and CB are stirred and dispersed at a high speed, thereby improving the dispersibility of CB and achieving uniform electrical characteristics.

Next, a preferred embodiment of the production method of the present invention will be described.
The present embodiment is characterized in that, in the molding step, a cylindrical member called a mandrel is disposed below the die, and the mandrel is cooled to a temperature equal to or lower than the glass transition temperature of the melt-kneaded product. FIG. 3 is a view showing an annular die composed of a die and a mandrel used when extrusion molding the conductive resin belt of the present invention. A mandrel 103 directly connected to the die is disposed below the die (spiral die) 101. The mandrel 103 is connected to an oil temperature controller (not shown), and temperature control is possible. For example, the mandrel temperature is set to be equal to or lower than the glass transition temperature of TPI, and solidified by the same time (peripheral length) as the mandrel diameter 104 is obtained by solidifying before the mandrel 103 is removed. When the cooling exceeds the glass transition temperature of the melt-kneaded product, the circumference may be smaller than the mandrel diameter, and a desired circumference may not be obtained. The mandrel 103 makes it possible to control the circumference (dimensions) stably, makes it less susceptible to outside air, less susceptible to vibrations, and facilitates setup prior to production. There is a great effect at. Further, for example, if the reduction of the characteristics of the intermediate transfer belt, particularly the anisotropy of the electrical characteristics is taken into consideration, the relationship between the die slip diameter 102 and the mandrel diameter 104 is preferably a one-to-one correspondence. About minus 10% of the diameter can be controlled without additional processing of the molding apparatus. In some cases, the mandrel diameter 104 is set to about minus 50% of the die slip diameter 102 for the purpose of particularly reducing the film thickness deviation of the intermediate transfer belt. Sometimes.
According to this preferred embodiment of the present invention, it is possible to realize a manufacturing method in which dimensional control is facilitated, production reproducibility is high, and film thickness deviation can be easily controlled.

Next, the image forming apparatus of the present invention will be described below.
In one embodiment, the image forming apparatus of the present invention includes at least an electrostatic latent image forming unit for forming an electrostatic latent image on the image carrier and an electrostatic latent image formed on the image carrier. Development means for forming a toner image using toner, primary transfer means for transferring the toner image on the image carrier onto the intermediate transfer belt, and secondary transfer for transferring the toner image on the intermediate transfer belt onto the recording medium And a fixing unit for fixing the toner image on the recording medium, wherein the intermediate transfer belt is the same as that of the first, second, third and / or fourth embodiment. It is a conductive resin belt.

  In another form, the image forming apparatus of the present invention includes at least an electrostatic latent image forming unit for forming an electrostatic latent image on the image carrier and an electrostatic latent image formed on the image carrier. Developing means for forming a toner image using toner, a transfer belt for conveying the recording medium to transfer the toner image on the image carrier to the recording medium, and a toner image on the image carrier being recorded An image forming apparatus comprising transfer means for transferring to a medium and fixing means for fixing a toner image on a recording medium, wherein the transfer belt is the first, second, third and / or fourth. It is the conductive resin belt of the embodiment

   FIG. 4 is a schematic view showing an example of the image forming apparatus of the present invention. The image forming apparatus shown in FIG. 4 includes yellow (hereinafter referred to as “Y”), cyan (hereinafter referred to as “C”), magenta (hereinafter referred to as “M”), black (hereinafter referred to as “M”). A color image is formed from the toner of four colors.

First, a basic configuration of an image forming apparatus (also referred to as a so-called “tandem type image forming apparatus”) that includes a plurality of image carriers and parallels the plurality of image carriers in the moving direction of the surface moving member. Will be described.
The image forming apparatus shown in FIG. 4 includes four photoconductors 1Y, 1C, 1M, and 1K as image carriers. Although a drum-shaped photoconductor is taken as an example here, a belt-shaped photoconductor can also be adopted. Each of the photoconductors 1Y, 1C, 1M, and 1K is rotationally driven in the direction of the arrow in FIG. 4 while contacting the intermediate transfer belt 10 that is a surface moving member. Each of the photoreceptors 1Y, 1C, 1M, and 1K is obtained by forming a photosensitive layer on a relatively thin cylindrical conductive substrate and forming a protective layer on the photosensitive layer. An intermediate layer may be provided therebetween.

  FIG. 5 is a schematic cross-sectional view showing an example of the configuration of the image forming unit in which the photoconductor in FIG. 4 is arranged. In addition, since the configuration around each of the photoreceptors 1Y, 1C, 1M, and 1K in the image forming units 2Y, 2C, 2M, and 2K is the same, only one image forming unit is illustrated, and symbols Y and C for color coding are illustrated. , M, and K are omitted. Around the photosensitive member 1, along the surface movement direction, a charging unit 3 as a charging unit, a developing unit 5, a transfer unit 6 that transfers a toner image on the photosensitive member 1 to a recording medium or an intermediate transfer belt 10, The cleaning means 7 for removing the untransferred toner on the photoreceptor 1 is arranged in this order. Between the charging unit 3 and the developing unit 5, exposure is performed based on the image data on the surface of the charged photoconductor 1 so that light emitted from the exposure unit 4 for writing the electrostatic latent image can pass to the photoconductor 1. Space is secured.

The charging unit 3 charges the surface of the photoreceptor 1 to a negative polarity. The charging unit 3 includes a charging roller as a charging member that performs a charging process by a so-called contact / proximity charging method. That is, the charging unit 3 charges the surface of the photosensitive member 1 by bringing the charging roller into contact with or close to the surface of the photosensitive member 1 and applying a negative bias to the charging roller. A DC charging bias is applied to the charging roller such that the surface potential of the photoreceptor 1 is −500V.
Note that a charging bias in which an AC bias is superimposed on a DC bias can also be used. The charging unit 3 may be provided with a cleaning brush for cleaning the surface of the charging roller. In addition, as the charging unit 3, a thin film may be wound around both end portions in the axial direction on the circumferential surface of the charging roller and installed so as to contact the surface of the photoreceptor 1. In this configuration, the surface of the charging roller and the surface of the photoreceptor 1 are extremely close to each other with a distance corresponding to the thickness of the film. Therefore, a discharge is generated between the surface of the charging roller and the surface of the photoreceptor due to the charging bias applied to the charging roller, and the surface of the photoreceptor is charged by the discharge.
An electrostatic latent image corresponding to each color is formed on the surface of the photoreceptor 1 charged in this way by exposure by the exposure means 4. The exposure unit 4 writes an electrostatic latent image corresponding to each color on the photoreceptor 1 based on image information corresponding to each color. The exposure means 4 is a laser system, but another system comprising an LED array and an image forming means can also be adopted.

  The toner replenished into the developing means 5 from the toner bottles 31Y, 31C, 31M, 31K is conveyed by the developer supply roller 5b and carried on the developing roller 5a. The developing roller 5 a is conveyed to a developing area facing the photoreceptor 1. Here, the developing roller 5 a moves in the same direction at a linear velocity faster than the surface of the photosensitive member 1 in a region facing the photosensitive member 1 (hereinafter also referred to as “developing region”). Then, the toner on the developing roller 5 a supplies the toner to the surface of the photosensitive member 1 while rubbing the surface of the photosensitive member 1. At this time, a developing bias of −300 V is applied to the developing roller 5a from a power source (not shown), thereby forming a developing electric field in the developing region. Then, between the electrostatic latent image on the photoreceptor 1 and the developing roller 5a, an electrostatic force directed toward the electrostatic latent image side acts on the toner on the developing roller 5a. As a result, the toner on the developing roller 5 a adheres to the electrostatic latent image on the photoreceptor 1. By this adhesion, the electrostatic latent image on the photoreceptor 1 is developed into a corresponding color toner image.

  The intermediate transfer belt 10 in the transfer unit 6 is stretched around three support rollers 11, 12, and 13 and is configured to endlessly move in the direction of the arrow in FIG. 4. On the intermediate transfer belt 10, toner images on the photoreceptors 1Y, 1C, 1M, and 1K are transferred so as to overlap each other by an electrostatic transfer method. Although there is a configuration using a transfer charger in the electrostatic transfer system, a configuration using a transfer roller 14 that generates less transfer dust is adopted here. Specifically, primary transfer rollers 14Y, 14C, 14M, and 14K as transfer means 6 are arranged on the back surface of the portion of the intermediate transfer belt 10 that contacts the photoreceptors 1Y, 1C, 1M, and 1K, respectively. Here, a primary transfer nip portion is formed by the portions of the intermediate transfer belt 10 pressed by the primary transfer rollers 14Y, 14C, 14M, and 14K and the photoreceptors 1Y, 1C, 1M, and 1K. When transferring the toner images on the photoreceptors 1Y, 1C, 1M, and 1K onto the intermediate transfer belt 10, a positive bias is applied to each primary transfer roller. As a result, a transfer electric field is formed in each primary transfer nip portion, and the toner images on the photoreceptors 1Y, 1C, 1M, and 1K are electrostatically attached to the intermediate transfer belt 10 and transferred.

When the toner image formed on the photoreceptor 1 is transferred to the intermediate transfer belt 10, the photoreceptor 1 and the intermediate transfer belt 10 are preferably in pressure contact. The pressure contact force at this time is preferably in the range of 10 N / m to 60 N / m.
Around the intermediate transfer belt 10, belt cleaning means 15 for removing toner remaining on the surface is provided. The belt cleaning unit 15 is configured to collect unnecessary toner adhering to the surface of the intermediate transfer belt 10 with a fur brush and a cleaning blade. The collected unnecessary toner is transported from the belt cleaning unit 15 to a waste toner tank (not shown) by a transport unit (not shown). Further, a secondary transfer roller 16 is disposed in contact with the portion of the intermediate transfer belt 10 stretched around the support roller 13. A secondary transfer nip portion is formed between the intermediate transfer belt 10 and the secondary transfer roller 16, and transfer paper as a recording medium is fed into this portion at a predetermined timing. This transfer paper is accommodated in a paper feed cassette 20 on the lower side of the exposure means 4 in the drawing, and is conveyed to the secondary transfer nip portion by a paper feed roller 21, a registration roller pair 22, and the like. Then, the toner images superimposed on the intermediate transfer belt 10 are collectively transferred onto the transfer paper at the secondary transfer nip portion. At the time of the secondary transfer, a positive bias is applied to the secondary transfer roller 16, and the toner image on the intermediate transfer belt 10 is transferred onto the transfer paper by a transfer electric field formed thereby.

  A heat fixing device 23 as a fixing unit is disposed downstream of the secondary transfer nip portion in the transfer paper conveyance direction. The heat fixing device 23 includes a heating roller 23a with a built-in heater and a pressure roller 23b for applying pressure. The transfer paper that has passed through the secondary transfer nip is sandwiched between these rollers and receives heat and pressure. As a result, the toner on the transfer paper is melted and the toner image is fixed on the transfer paper. Then, the fixed transfer paper is discharged by a paper discharge roller 24 onto a paper discharge tray on the upper surface of the apparatus.

In the developing unit 5, a developing roller 5a as a developer carrying member is partially exposed from an opening of the casing. Further, here, a one-component developer containing no carrier is used. The developing means 5 receives the toner of the corresponding color from the toner bottles 31Y, 31C, 31M, and 31K shown in FIG. The toner bottles 31Y, 31C, 31M, and 31K are configured to be detachable from the main body of the image forming apparatus so that they can be replaced individually. With such a configuration, only the toner bottles 31Y, 31C, 31M, and 31K may be replaced at the time of toner end. Therefore, other components that have not yet reached the end of their life at the time of toner end can be used as they are, and the user's expense can be reduced.
The developer (toner) in the developer container 5d is conveyed to the nip portion of the developing roller 5a as a developer carrying member for carrying the developer supplied to the photoreceptor 1 on the surface while being agitated by the supply roller 5b. It is. At this time, the supply roller 5b and the developing roller 5a are rotated in the reverse direction (counter rotation) at the nip portion. Further, the amount of toner on the developing roller 5a is regulated by a regulating blade 5c as a developer layer regulating member provided so as to come into contact with the developing roller 5a, and a thin toner layer is formed on the developing roller 5a. The toner is rubbed between the nip portion of the supply roller 5b and the developing roller 5a, the regulating blade 5c, and the developing roller 5a, and is controlled to an appropriate charge amount.

  In the image forming apparatus, a plurality of components such as a latent image carrier, a charging unit, and a developing unit are integrally coupled as a process cartridge, and the process cartridge is an image of a copying machine, a printer, or the like. It can be configured to be detachable from the forming apparatus main body.

  In addition to the intermediate transfer belt of the image forming apparatus described above, the conductive resin belt of the present invention is also capable of forming an image by electrophotography or electrostatic printing such as a copying machine, laser beam printer, or facsimile. It is suitable as a conveying belt, a transfer belt, a fixing belt, and a developing belt used in the apparatus.

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

[Examples 1-7, Comparative Examples 1-4]
First, the resin components shown in Table 1 were pulverized using a pulverizer (manufactured by Seishin Enterprise).
Subsequently, each compounding component shown in Table 1 was added to the obtained pulverized particles, and the mixture was mixed and stirred at 2000 rpm for 3 minutes using a high-speed stirrer (manufactured by Mitsui Mining) to obtain a molding mixture.
In addition, the numerical value about the compounding quantity of each component shows a mass part.
The obtained molding mixture was melt-kneaded at 300 to 370 ° C. using a twin-screw extrusion kneader (L / D = 60) to be pelletized.
This pellet was extruded at 300 to 370 ° C. using an annular die shown in FIG. 3 to obtain a seamless conductive resin belt having an inner diameter of 310 mm and a width of 235 mm.

The following characteristics were evaluated for the conductive resin belts obtained in each Example and Comparative Example.
The evaluation results are shown in Table 1.

[Thermal characteristics]
(1) Heat of fusion X-DSC7000 (manufactured by Shimadzu Corporation) was used for measurement, and the temperature increase rate was 10 ° C / min and the mass was 5 mg.

[Image evaluation]
In the following image evaluation, MPC6003 (manufactured by Ricoh) was used.
(1) Durability evaluation: A conductive resin belt having no cracks, breaks, or backside scratches at 240 kp or more is marked as ◯, those that are generated at 120 kp or more and less than 240 kp are Δ, and those that are generated at less than 120 kp are × It was.
(2) Abnormal image evaluation: An image without an abnormal image (white spot, sticky, blur, etc.) was marked with ◯, a slight occurrence was marked with △, and the others were marked with ×.
(3) Evaluation of cleaning property A case where there was no cleaning failure was indicated by ◯, and a case where it was not indicated by ×.
(4) Filming property evaluation The initial If value was 10 mA and the rate of increase in If value after passing 10 kp was within 150% was evaluated as ◯, and the others were evaluated as X.

[Mechanical properties]
(1) Martens hardness Using an ultra-micro hardness meter HM2000LT (manufactured by Fischer), the load was controlled, and the test was performed under the conditions of an increase in load of 5 mN / 10 s (the same condition for decrease) and a creep of 10 s.
(2) Tensile elastic modulus A test was conducted in accordance with JIS K7127.
(3) Bending resistance (MIT test)
The test was conducted according to JIS P8115.

[Electrical characteristics]
The electrical properties were measured using Hiresta UP MCP-HT450 (Mitsubishi Chemical Analytech).
(1) Surface resistivity The surface resistivity was measured at a voltage of 500V. It is desirable to be in the range of 10 ⁸ to 10 ¹² [Ω / □].
(2) Volume resistivity The volume resistivity was measured at a voltage of 100V. It is desirable to be in the range of 10 ⁸ to 10 ¹² [Ω · cm].
(3) Surface resistivity / voltage dependence The difference between the surface resistance value measured at 100V and the surface resistance value measured at 500V was measured. The difference is desirably 1.0 or less.
(4) Volume resistivity / voltage dependence The difference between the volume resistance value measured at 100V and the volume resistance value measured at 250V was measured. The difference is desirably 2.0 or less.
(5) Surface resistivity / environment dependency The difference between the surface resistance value measured at 10 ° C. and 10 RH% and the surface resistance value measured at 30 ° C. and 90% was measured. The difference is desirably 0.5 or less.
(6) Volume resistivity / environment dependency The difference between the volume resistance value measured at 10 ° C. and 10% and the volume resistance value measured at 30 ° C. and 90 RH% was measured. The difference is desirably 1.0 or less.

[Flame retardance]
In the UL94 standard, VTM-1 or higher was marked with ◯, and the others were marked with x.
[Surface smoothness]
A 20 degree gloss (PG-1 manufactured by Nippon Denshoku Industries Co., Ltd.) after a paper passing test corresponding to 10,000 sheets was measured.
[Resistance controllability]
The volume resistance change rate (Log Ω · cm / ° C.) at a molding temperature of 340 ° C. and 330 ° C. is 0.2 or less, ◯ is 0.2 to 0.3 or less, and the others are X.
[Molding stability]
A sample having a fluctuation range of the molding resin pressure of 10% or less by an extrusion molding machine having a die shape of φ310 mm was rated as “◯”, and the others were marked as “X”.
[Handling]
When MPC6003 (manufactured by Ricoh) was removed from the machine, the belt was not marked with irregularities such as kinks and dents, and the others were marked with x.

  From the results shown in Table 1, the conductive resin belts of each example have mechanical characteristics, electrical characteristics, flame retardancy, surface glossiness (surface smoothness), durability, and image compared to the conductive resin belts of each comparative example. It can be seen that it is excellent in various properties such as formability, filming property, resistance controllability, molding stability, and handleability.

DESCRIPTION OF SYMBOLS 1 Photoconductor 1Y, 1C, 1M, 1K Photoconductor 2Y, 2C, 2M, 2K Image formation part 3 Charging means 4 Exposure means 5 Developing means 5a Developing roller 5b Developer supply roller 5c Regulating blade 5d Developer container 6 Transfer means 7 Cleaning means 10 Intermediate transfer belt 11, 12, 13 Support roller 14 Transfer rollers 14Y, 14C, 14M, 14K Primary transfer roller 15 Belt cleaning means 16 Secondary transfer roller 20 Paper feed cassette 21 Paper feed roller 22 Registration roller pair 23 Heating Fixing device 23a Heating roller 23b Pressure roller 24 Paper discharge rollers 31Y, 31C, 31M, 31K Toner bottle 101 Spiral die 102 Die slip diameter 103 Mandrel 104 Mandrel diameter

JP 2005-112942 A JP 2012-133220 A JP 2006-69046 A JP 2000-137389 A JP 2001-125396 A JP 2008-15491 A

Claims (8)

At least a resin belt containing polyimide and carbon black,
The resin belt is one in which a heat of fusion of 15 mJ / mg to 25 mJ / mg is detected in a temperature range of 250 ° C. to 350 ° C. by thermal analysis using a differential scanning calorimeter,
The compounding amount of the carbon black with respect to 100 parts by mass of the polyimide is 5 to 20 parts by mass,
The resin belt has an average thickness of 40 to 120 μm,
Said resin belt Martens hardness is at 120 N / mm ² or more 280N / mm ² or less, and the resin belt modulus measured in tensile properties test method specified in JIS K7127 is less than 2500MPa or more 1500MPa Characteristic resin belt.   2. The resin belt according to claim 1, wherein the resin belt has a number of reciprocal bendings measured in a folding strength test method defined in JIS P8115 of 2000 times or more and 20000 times or less. The carbon black is at least DBP absorption is from 200 cm ^3/100 g or more of the carbon black and one 100 cm ^3/100 g 2 or more comprising one less carbon black, the amount of the carbon black is the polyimide 100 parts by The resin belt according to claim 1, wherein the amount is 18 parts by mass or less based on the weight of the resin belt. The resin belt has a volume resistivity (Rv100 [Ω · cm]) at 100 V of 10 ⁸ to 10 ¹² [Ω · cm] and a surface resistivity (Rs500 [Ω]) at 500 V of 10 ⁸ to 10. ^{It is 12} [(ohm)], The resin belt as described in any one of Claims 1-3 characterized by the above-mentioned.   It is a method of manufacturing the resin belt as described in any one of Claims 1-4, Comprising: Polyimide particle | grains and carbon black are stirred at 1000-3000 rpm at high speed, The mixture obtained by the said stirring is 300-. A method for producing a resin belt, comprising: a step of melt-kneading at 370 ° C. to obtain a melt-kneaded product; and a step of extruding the melt-kneaded product from a die to obtain a molded product.   6. The method for producing a resin belt according to claim 5, wherein in the molding step, a mandrel is disposed at a lower portion of a die, and the melt-kneaded product is cooled to a glass transition temperature or lower by the mandrel.   At least an electrostatic latent image forming unit for forming an electrostatic latent image on the image carrier, a developing unit that uses toner to form a toner image on the electrostatic latent image formed on the image carrier, and an image A primary transfer means for transferring the toner image on the carrier onto the intermediate transfer belt, a secondary transfer means for transferring the toner image on the intermediate transfer belt onto the recording medium, and fixing the toner image on the recording medium. An image forming apparatus comprising a fixing unit, wherein the intermediate transfer belt is the resin belt according to claim 1. At least an electrostatic latent image forming unit for forming an electrostatic latent image on the image carrier, a developing unit that uses toner to form a toner image on the electrostatic latent image formed on the image carrier, and an image A transfer belt for conveying the recording medium to transfer the toner image on the carrier to the recording medium; a transfer means for transferring the toner image on the image carrier to the recording medium; and a toner on the recording medium An image forming apparatus comprising: a fixing unit that fixes an image, wherein the transfer belt is the resin belt according to claim 1.