JP3874360B2 - Intermediate transfer member, electrophotographic apparatus using the intermediate transfer member, and method of manufacturing intermediate transfer member - Google Patents

Description

  The present invention relates to an intermediate transfer member that temporarily holds an image in an image forming process, an electrophotographic apparatus using the intermediate transfer member, and a method of manufacturing the intermediate transfer member.

An electrophotographic apparatus using an intermediate transfer member is very effective for creating a color image by sequentially laminating and transferring a plurality of component color images. For example, color misregistration can be reduced when the toner images of the respective colors are overlaid, compared to the transfer method described in JP-A-63-301960. Furthermore, the image is transferred from the intermediate transfer body to the recording medium without the need for holding means (for example, gripping, adsorbing, giving a curvature, etc.) as shown in FIG. 1 of JP-A-63-301960. Therefore, a variety of recording media can be selected. For example, transfer is possible from thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper), regardless of whether the width is wide or short. Therefore, transfer is possible up to envelopes, postcards, label papers and the like.

  Because of these advantages, color copiers, color printers and the like using an intermediate transfer member have already started to operate in the market.

  As the shape of the intermediate transfer member, a drum-like or belt-like shape is conceivable. However, the belt-like intermediate transfer member is used because the cost of the entire apparatus can be reduced and the degree of freedom in designing the transfer member arrangement is high. It is valid.

  As the belt-shaped intermediate transfer member, for example, as described in JP-A-59-77467, an intermediate transfer member in which a transfer layer such as silicone rubber or fluorine rubber is laminated on a heat-resistant resin film substrate such as polyimide. Has been proposed.

  However, the use of a belt-shaped intermediate transfer member has the following problems.

  That is, when an intermediate transfer member is made of an elastomer having a low tensile elastic modulus, the relative position between the intermediate transfer member and the photosensitive drum in one color image transfer cycle changes due to “elongation”, and the toner There is a problem that color misregistration occurs when images are superimposed.

  Conversely, when an intermediate transfer member is made using only a resin film having a relatively large tensile elastic modulus compared to an elastomer, the intermediate transfer member does not stretch, but creep does not occur when used for a long time (several thousand hours). In some cases, the outer peripheral length is longer than specified.

  Further, in the case of a resin film, since the hardness (compression elastic modulus) is higher than that of an elastomer, as shown in FIG. 4, other than the contour portion of the image 100 is not sufficiently transferred at the time of image transfer, so-called “cold” is called. There was a problem that the phenomenon occurred.

  In order to prevent elongation and creep of the intermediate transfer member, a core material (fiber or cloth) may be embedded in the intermediate transfer member by a method such as impregnation or pressing. Japanese Utility Model Laid-Open No. 3-69166 describes an intermediate transfer belt in which a thread or cloth core is provided on the inner surface of a rubber belt. In this case, microscopic electric resistance unevenness occurs in the intermediate transfer member, and the transfer current varies, and a good image may not be obtained.

  In addition, when a belt-shaped intermediate transfer member is used, the belt thickness unevenness and the distance between the support rollers that stretch the belt are not uniform, so the force that the belt conveys to the support rollers becomes uneven, and the belt position is on one side. A so-called “shift” occurred. As a result, there are problems such as cracks and tears at the belt end, and misalignment when the component color images are superimposed.

  As a method for preventing the belt-shaped intermediate transfer member from shifting, for example, there is a method in which a guide rib is attached to the inner side surface of the intermediate transfer member and a guide groove provided on a support roller is caused to travel. In addition, belt end detection sensors are provided on both sides of the belt-shaped intermediate transfer member, and when a shift occurs, the sensor detects the end of the belt-shaped intermediate transfer member and changes the position of the support roller to return the shift. It is also possible.

  Furthermore, you may form the protrusion which controls the shift | offset | difference of a belt-shaped intermediate transfer body on the outer peripheral surface of a support roller. However, any of the methods for preventing the shift is complicated and expensive.

  An object of the present invention is to provide an intermediate transfer member excellent in durability that does not cause elongation or creep.

  Another object of the present invention is to provide an intermediate transfer member that does not generate a shift without using a shift prevention member.

  Another object of the present invention is to provide an electrophotographic apparatus capable of obtaining a clear image without occurrence of voids or color misregistration.

  Another object of the present invention is to provide a method for producing an intermediate transfer member that can efficiently produce the intermediate transfer member of the present invention.

The present invention has a base layer and a surface layer provided on the base layer, the base layer is formed of polyurethane, and the surface layer is polyphenylsulfone, polysulfone, polyethersulfone, polyester, polyacetal, polyarylate, It is formed of any engineering plastic of polyamide and polycarbonate,
On the surface layer, at least one of ETFE (ethylene-tetrafluoroethylene copolymer) or PTFE (polytetrafluoroethylene) fluorine resin powder, molybdenum disulfide, graphite, graphite fluoride, boron nitride, and silicone resin particles. An intermediate transfer member characterized by containing a lubricant.

  The present invention also provides an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, an image exposing unit that performs image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, An electrophotographic apparatus comprising: a developing unit that develops the electrostatic latent image to form a toner image on the electrophotographic photosensitive member; and an intermediate transfer member to which the toner image is transferred. The electrophotographic apparatus is an intermediate transfer member.

Further, the present invention provides a fluororesin powder of ETFE (ethylene-tetrafluoroethylene copolymer) or PTFE (polytetrafluoroethylene) on the inner surface of the rotor by rotating a cylindrical rotor, molybdenum disulfide, graphite. A lubricant containing at least one of graphite fluoride, boron nitride, and silicone resin particles, and any one of polyphenylsulfone, polysulfone, polyethersulfone, polyester, polyacetal, polyarylate, polyamide, and polycarbonate A process for forming an engineering plastic surface layer, and a process for forming a polyurethane base layer on the inner surface of the surface layer without removing the surface layer from the rotor. is there.

  The intermediate transfer member of the present invention is excellent in durability without causing elongation or creep. Further, the electrophotographic apparatus using the intermediate transfer member of the present invention does not cause voids or color misregistration. Furthermore, according to the method for producing an intermediate transfer member of the present invention, an intermediate transfer member can be produced efficiently.

  As shown in FIG. 1, the intermediate transfer member of the present invention has at least a base layer 21 and a surface layer 22 provided on the base layer 21. The base layer 21 is formed of an elastomer, and the surface layer 22 is formed of an engineering plastic.

  The intermediate transfer member of the present invention has an endless belt shape or a cylindrical shape, and is preferably seamless.

  The elastomer used for the base layer 21 is polyurethane.

  The base layer 21 preferably has a hardness in the range of 40 degrees to 70 degrees from the viewpoint of preventing hollowing out. In the present invention, the hardness is a value measured using a JIS-A type hardness meter.

  The thickness of the base layer 21 is preferably 100 μm-1500 μm, more preferably 500 μm-1000 μm.

The engineering plastic used for the surface layer 22 refers to a polymer compound that hardly deforms even at high temperatures and retains most of the mechanical properties at room temperature. In particular, the engineering plastic used in the present invention has physical properties such as a tensile strength of 50 N / mm ² or more, a flexural modulus of 2000 N / mm ² or more, and a heat distortion temperature of 100 ° C. or more. Furthermore, those having a tensile strength of 5000 / mm ² or less, a flexural modulus of 200000 N / mm ² or less, and a heat distortion temperature of 1500 ° C. or less are preferable. In the present invention, the tensile strength is a value measured according to ASTM D-638. Further, the flexural modulus is a value measured according to ASTM D-790, and the thermal deformation temperature is a value measured according to ASTM D-648.

  The engineering plastic used for the surface layer 22 is polyester, polyarylate with excellent mechanical properties, heat resistance and durability, polyacetal, polyamide, polycarbonate among the so-called five major engineering plastics, polyether with excellent long-term dimensional stability. Sulphone, polysulfone, and polyphenylsulfone. Engineering plastics have a high tensile modulus among resins.

  For this reason, the intermediate transfer member of the present invention does not stretch and is excellent in dimensional stability.

  The surface layer 22 may contain synthetic rubber such as NBR, EPDM or CR, urethane, etc. in addition to the engineering plastic. However, the content of the engineering plastic is preferably 50% by weight or more with respect to the surface layer 22.

Tensile modulus of the surface layer 22 is 2000N / mm ² or more, and more preferably 2000-10000N / mm ^2. If the tensile modulus of the surface layer is too small, the intermediate transfer member is easily deformed. On the other hand, if the elastic modulus is too large, it will be difficult to follow the outer peripheral surface of the support roller, and it will be easy to break. In the present invention, the tensile elastic modulus is a value measured according to JIS-7127 at a tensile speed of 10 mm / min.

  The thickness of the surface layer 22 is preferably thin so as not to kill the flexibility of the base layer 21, and is preferably 1 mm or less, and more preferably 10 μm to 300 μm.

  The intermediate transfer member of the present invention preferably has a hardness of 40-100 degrees, more preferably 60-100 degrees. If the hardness is too small, the intermediate transfer member is likely to be deformed, and toner images are likely to be misaligned. On the other hand, if the hardness is too large, voids are likely to occur. In the present invention, the hardness of the intermediate transfer member is a value measured from the surface layer side using a JIS-A type hardness meter.

  As a method for producing the intermediate transfer member of the present invention, a centrifugal molding method is preferable in that the base layer and the surface layer can be continuously formed with the same production apparatus.

  Since the intermediate transfer member of the present invention does not use an adhesive for bonding the base layer and the surface layer, the thickness of the intermediate transfer member can be made uniform. In particular, one of polyurethane, chloroprene rubber, isoprene rubber, nitrile rubber and styrene-butadiene rubber is used as the base layer, and polyphenylsulfone, polysulfone, polyethersulfone, polyester, polyacetal, polyarylate, polyamide, polycarbonate, polyphenylene as the surface layer. When any one of ether, polyether imide, polyamide imide, polyphenylene sulfide, and polyimide is used, the base layer and the surface layer are preferably firmly bonded. Further, as in the present invention, it is preferable to use polyurethane as the base layer and use any of polyphenylsulfone, polysulfone, polyethersulfone, polyester, polyacetal, polyarylate, polyamide and polycarbonate as the surface layer. . Furthermore, it is preferable to use polyurethane as the base layer and polyphenylsulfone, polyethersulfone, polyester and polyamide as the surface layer.

  The apparatus shown in FIG. 2 is a centrifugal molding machine that performs a centrifugal molding method, and a cylindrical rotor 72 is provided in a heating furnace 74. A shaft 77 is attached to the center of rotation of the cylindrical rotor 72. The shaft 77 is interlocked with the rotating shaft 79 of the drive motor 75 via the drive belt 76. Around the rotor 72, heating fins 73 using steam are arranged to heat the rotor 72.

  In this way, first, the material 78 of the molded product is introduced into the cylindrical rotor 72 in a liquid state. Next, the drive motor 75 is driven to rotate the cylindrical rotor 72 and the material 78 is heated by the heating fins 73. As a result, an endless belt-shaped molded product is formed on the inner surface of the rotor 72.

  When the intermediate transfer member of the present invention is manufactured by the centrifugal molding method, first, the surface layer raw material is charged into the cylindrical rotor 72 to form the surface layer. Thereafter, without removing the surface from the rotor 72, the raw material for the base layer is further introduced into the cylindrical rotor 72 to form the base layer on the inner surface of the surface layer. After the base layer molding, it is cooled to room temperature and the molded product is removed from the centrifugal molding machine to obtain the intermediate transfer member of the present invention.

  The rotational speed of the cylindrical rotor 72 is preferably 200 RPM-2000 RPM. The temperature of the heating fin 73 is preferably 70 ° C. to 200 ° C. although it depends on the material of the molded product.

  Further, since the surface roughness of the intermediate transfer member is determined by the inner surface of the cylindrical rotor 72, if the inner surface of the rotor 72 is accurately finished, it is not necessary to polish the intermediate transfer member after molding.

The intermediate transfer member of the present invention preferably has a volume resistivity in the thickness direction of 10 ⁵ -10 ¹² Ω · cm, more preferably 10 ⁸ -10 ¹⁰ Ω · cm. If the volume resistivity of the intermediate transfer member is too small, an excessive transfer current flows. On the other hand, if the volume resistivity is too large, a sufficient current cannot be obtained, so that the toner cannot be transferred satisfactorily. In the present invention, the volume resistivity is a value measured by applying a voltage of 500 V in accordance with JIS-6911.

  In order to adjust the volume resistivity of the intermediate transfer member, a conductive filler may be contained in the base layer, the surface layer, or both the base layer and the surface layer. Any electrically conductive filler can be used as long as it is normally used. However, carbon fillers such as furnace black, acetylene black, ketjen black, graphite, and carbon fiber, tin oxide, zinc oxide, and oxide are used. A metal oxide filler obtained by doping titanium or the like with impurity ions is particularly preferable.

  The content of the conductive filler is preferably 1 to 35% by weight with respect to each layer.

  In order to increase the transfer efficiency of the toner image on the intermediate transfer member, or to maintain the surface characteristics (particularly roughness) of the intermediate transfer member over a long period of time, a lubricant is contained in the surface layer. The lubricant is a fluororesin powder such as ETFE (ethylene-tetrafluoroethylene copolymer) or PTFE (polytetrafluoroethylene), molybdenum disulfide, graphite, graphite fluoride, boron nitride, or silicone resin particles.

  The content of the lubricant is preferably 25 to 50% by weight based on the surface layer. Alternatively, a lubricating layer containing a lubricant may be provided on the surface layer. Also in the case of providing the lubricating layer, the content of the lubricant is preferably 25 to 50% by weight with respect to the lubricating layer.

  The electrophotographic apparatus of the present invention will be described with reference to FIG.

  Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) that is repeatedly used, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed (process speed).

  In the rotating process, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2 and then subjected to image exposure 3 by an image exposure means (not shown) to obtain a target color. An electrostatic latent image corresponding to a first color component image (for example, a magenta component image) of the image is formed.

  Next, the electrostatic latent image is developed by the first developing device 41 (magenta developing device) with the first color magenta toner M. At this time, the second to fourth developing devices 42, 43, 44 (cyan, yellow, black) are turned off and do not act on the photosensitive drum 1, and the magenta toner image of the first color is the second toner image. -Not affected by the fourth developing units 42-44.

  The magenta toner image of the first color carried on the photosensitive drum 1 is subjected to a primary transfer bias voltage applied to the intermediate transfer member 20 in the process of passing through the nip portion between the photosensitive drum 1 and the intermediate transfer member 20. Transfer is performed on the outer peripheral surface of the intermediate transfer body 20. The primary transfer bias voltage is applied by a bias power supply 30.

  The intermediate transfer member 20 is supported by support rollers 60, 61, 62, and 63, and is rotationally driven in the clockwise direction indicated by an arrow at the same peripheral speed as that of the photosensitive drum 1.

  The surface of the photosensitive drum 1 after the transfer of the first color magenta toner image is cleaned by the cleaning device 14.

  Similarly, the second color cyan toner image, the third color yellow toner image, and the fourth color black toner image are sequentially transferred onto the intermediate transfer body 20 to form a composite color toner image corresponding to the target color image. Is done.

  Reference numeral 25 denotes a transfer roller, which is disposed so as to be able to come into contact with or move away from the intermediate transfer body 20. The toner image on the intermediate transfer member 20 is transferred to the recording material 24 held between the intermediate transfer member 20 and the transfer roller 25. A secondary transfer bias voltage is applied to the transfer roller 25 by a bias power source 29, and the toner image is transferred to the recording material 24 by the secondary transfer bias voltage.

  The transfer material 24 such as paper is supplied from the paper feed cassette 9 in synchronization with the rotation of the intermediate transfer body 20. The transfer roller 25 is separated from the intermediate transfer body 20 when the toner image is transferred from the photosensitive drum 1 to the intermediate transfer body 20.

  The transfer material 24 onto which the toner image has been transferred is conveyed to the fixing device 51 and fixed by heating. Thereafter, the residual toner on the intermediate transfer member 20 is cleaned by the cleaner 35 that is in contact with the intermediate transfer member.

  The primary transfer bias voltage is preferably +2 kV− + 5 kV with a polarity opposite to that of the toner. The secondary transfer bias voltage is preferably +1 kV− + 3 kV.

  In the above description of the apparatus, a color electrophotographic apparatus is taken as an example, but the intermediate transfer member of the present invention can naturally be used in a monochrome electrophotographic apparatus.

  In the intermediate transfer member of the present invention, the friction coefficient of the inner side surface (the surface on the support roller 60-63 side) is preferably 0.7 or less, more preferably 0.1 to 0.7. The intermediate transfer member having a large coefficient of friction on the inner surface is caused by non-uniform spacing between the support rollers 60-63 that support the intermediate transfer member when the electrophotographic apparatus is not provided with a shift prevention member. Then, a shift occurs. By setting the friction coefficient of the inner surface to 0.7 or less, it is possible to prevent the occurrence of deviation without providing a deviation prevention member. Alternatively, by providing a simple guide, it is possible to prevent deviation from occurring without damaging the intermediate transfer member.

  In order to set the friction coefficient of the inner side surface of the intermediate transfer member to 0.7 or less, for example, a lubricating layer formed by containing a lubricant in an elastomer may be provided on the inner side surface of the intermediate transfer member.

  Examples of the lubricant contained in the lubricating layer include metal soaps such as stearates, fatty acid amides, fluororesin powders such as ETFE and PTFE, molybdenum disulfide, graphite, graphite fluoride, boron nitride, silicon nitride, silicone resin particles Silicone oil and silicone rubber particles are preferred. The average particle size of the lubricant is preferably 0.1 μm-3 μm.

  As the elastomer used for the lubricating layer, any elastomer can be used as long as it is used for the aforementioned base layer. However, in order to eliminate the need for an adhesive, the elastomer used for the lubricating layer and the base layer is the same or at least good. Those having affinity are preferred.

  The content of the lubricant is preferably 15 to 50% by weight with respect to the lubricating layer. The thickness of the lubricating layer is preferably 5 μm-30 μm. The lubricating layer can be provided by a centrifugal molding method following the formation of the base layer.

  A lubricant may be contained in the base layer without providing the lubricant layer. In this case, the content of the lubricant is preferably 15 to 50% by weight with respect to the base layer.

  Further, by using a low friction elastomer such as silicone graft urethane for the base layer material without using a lubricant, the inner surface of the intermediate transfer member can be made low friction.

  The coefficient of friction of the inner surface of the intermediate transfer member is a value measured according to JIS-7125.

[Reference Example 1]
(Formation of surface layer)
100 parts by weight of polyphenylsulfone is used as a binder, dissolved in a solvent dimethylacetamide (DMAC) so that the binder concentration is 20% by weight, and conductive carbon (Ketjen Black 600JD, manufactured by Ketjen Black International) 7 Part by weight was added and dispersed for 30 minutes by a paint shaker. This dispersion was put into the centrifugal molding machine shown in FIG. 2 and dry-molded under conditions of a rotor rotational speed of 1500 RPM and a rotor internal temperature of 120 ° C. for 30 minutes.

  The rotor 2 has an inner diameter of 140 mm and a length of 350 mm, and is subjected to hard chrome plating.

(Creation of base layer)
The base layer was made of polyurethane. 100 parts by weight of polyol is heated to 80 ° C., 10 parts by weight of conductive carbon (Ketjen Black 600JD) is added and dispersed for 1 hour with a stirrer, and added to 60 parts by weight of isocyanate heated to 80 ° C. Disperse with a stirrer for 3 minutes. This dispersion was put into a centrifugal molding machine following the surface layer formation, and heat-cured under the conditions of 2000 RPM, 120 ° C. for 3 hours.

  Thereafter, aging was carried out at 80 ° C. for 15 hours, followed by natural cooling to room temperature, taking out the molded product from the molding machine and cutting the end portion, thereby obtaining the intermediate transfer member of the present invention.

The obtained intermediate transfer member had a surface layer thickness of 150 μm, a base layer thickness of 800 μm, a length of 250 mm, a hardness of 91, and a volume resistance value of 10 ⁸ Ω · cm.

  The intermediate transfer member thus obtained was mounted on the electrophotographic apparatus shown in FIG. 3, and a tension of 50 N was applied to the intermediate transfer member to conduct an image output durability test. In the electrophotographic apparatus used in this embodiment, a protrusion for regulating the deviation is formed on the outer peripheral surface of the support roller that supports the intermediate transfer member. In the test, a color test pattern image was continuously formed on 300 sheets of recording paper, then continuous operation was performed only for 200 hours without recording (the tension was constant), and then 300 sheets of recording paper were again formed. The image forming cycle was repeated, and the evaluation of the image and the measurement of the elongation amount of the intermediate transfer member were performed from the start of the test to 2000 hours. The image evaluation was performed on the image formed on the 300th recording paper of each cycle, and the occurrence of toner image overlay and omission was investigated by microscopic observation. As a result, no void occurred in any of the images. Further, after the endurance test, the outer peripheral length of the intermediate transfer member was measured, and the elongation was calculated by the following equation.

Elongation rate (%) = (peripheral length after completion of test−peripheral length before start of test) ÷ outer peripheral length before start of test × 100
The evaluation results are shown in Table 1. In the table, the overlay error data is for the last image.

[Reference Example 2]
An intermediate transfer member was prepared using the same material as in Reference Example 1 except that polyethersulfone was used as the surface layer binder.

The obtained intermediate transfer member had a surface layer thickness of 100 μm, a base layer thickness of 700 μm, a length of 250 mm, a hardness of 90, and a volume resistance of 10 ⁷ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 1.

[Reference Example 3]
An intermediate transfer member was prepared by using polysulfone as a binder for the surface layer, using dimethylformamide (DMF) as a solvent, and using the same materials as in Reference Example 1 except for that.

The obtained intermediate transfer member had a surface layer thickness of 80 μm, a base layer thickness of 900 μm, a length of 250 mm, a hardness of 91, and a volume resistance value of 10 ⁹ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 1.

[Reference Example 4]
An intermediate transfer member was prepared using the same material as in Reference Example 1 except that polyetherimide was used as a binder for the surface layer and methylene chloride was used as the solvent.

The obtained intermediate transfer member had a surface layer thickness of 50 μm, a base layer thickness of 600 μm, a length of 250 mm, a hardness of 88, and a volume resistance value of 10 ⁸ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 1.

[Reference Example 5]
(Formation of surface layer)
Use 100 parts by weight of polyphenylsulfone as a binder, dissolve in solvent DMAC so that the binder concentration is 20% by weight, add 8 parts by weight of conductive carbon (Ketjen Black 600JD), and disperse with a paint shaker for 30 minutes. I let you. This dispersion was put into the same centrifugal molding machine as in Reference Example 1, and dry molding was performed under conditions of a rotor rotational speed of 1500 RPM and a rotor internal temperature of 120 ° C. for 30 minutes.

(Creation of base layer)
Liquid silicone was used as a binder. Dispersion was performed with a stirrer at a ratio of 100 parts by weight of liquid silicone, 50 parts by weight of a curing agent, and 8 parts by weight of conductive carbon (Ketjen Black 600JD), and the mixture was heated to 60 ° C. to lower the viscosity. This dispersion was put into a centrifugal molding machine following surface layer formation, and heat-cured under the conditions of 2000 RPM, 150 ° C., and 1 hour.

  Thereafter, it was naturally cooled to room temperature, and the molded product was taken out from the molding machine and cut at the end to obtain the intermediate transfer member of the present invention.

The obtained intermediate transfer member had a surface layer thickness of 250 μm, a base layer thickness of 700 μm, a length of 250 mm, a hardness of 90, and a volume resistance value of 10 ⁵ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 2.

[Reference Example 6]
(Formation of surface layer)
A surface layer similar to that of Reference Example 5 was formed.

(Creation of base layer)
Dispersed in 100 parts by weight of EPDM dissolved in a solvent at a ratio of 10 parts by weight of conductive carbon (Ketjen Black 600JD) with a paint shaker for 20 minutes. After the surface layer formation, this dispersion was put into a centrifugal molding machine, and heat-dried under the conditions of a rotor rotational speed of 2000 RPM and a rotor temperature of 90 ° C. for 1 hour.

  Thereafter, it was naturally cooled to room temperature, and the molded product was taken out from the molding machine and cut at the end to obtain the intermediate transfer member of the present invention.

The obtained intermediate transfer member had a surface layer thickness of 250 μm, a base layer thickness of 1000 μm, a length of 250 mm, a hardness of 95, and a volume resistance value of 10 ⁶ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 2.

[Reference Example 7] <Resistance adjustment with tin oxide>
(Formation of surface layer)
100 parts by weight of polyphenylsulfone was used as a binder, dissolved in a solvent DMAC so that the binder concentration was 20% by weight, 18 parts by weight of tin oxide (Sb-doped product) was added, and the mixture was dispersed for 30 minutes by a paint shaker. This dispersion was put into the centrifugal molding machine shown in FIG. 2 and dry-molded under conditions of 1500 RPM and 120 ° C. for 30 minutes.

(Creation of base layer)
A base layer was formed using the same material as in Reference Example 1.

The obtained intermediate transfer member had a surface layer thickness of 50 μm, a base layer thickness of 500 μm, a length of 250 mm, a hardness of 85, and a volume resistance value of 10 ¹⁰ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 3.

[Reference Example 8] <Resistance adjustment with carbon fiber>
An intermediate transfer member was prepared using the same material as in Reference Example 7 except that 4 parts by weight of carbon fiber was used as the conductive material instead of tin oxide. Carbon fibers having an average fiber diameter of 5 μm and an average fiber length of 20 μm were used.

The obtained intermediate transfer member had a surface layer thickness of 90 μm, a base layer thickness of 700 μm, a length of 250 mm, a hardness of 88, and a volume resistance value of 10 ⁸ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 3.

[Example 1] <Surface property modification by PTFE>
(Formation of surface layer)
100 parts by weight of polyphenylsulfone is used as a binder, dissolved in a solvent DMAC so that the binder concentration is 20% by weight, 8 parts by weight of conductive carbon (Ketjen Black 600JD), and toner releasability (transferability) As a modifier for improvement, 30 parts by weight of PTFE particles (average particle size 0.3 μm) were added and dispersed for 30 minutes by a paint shaker. This dispersion was subjected to dry molding under the conditions of 1500 RPM, 120 ° C., and 30 minutes using the centrifugal molding machine shown in FIG.

(Creation of base layer)
A base layer was prepared using the same material as in Reference Example 1.

The obtained intermediate transfer member had a surface layer thickness of 150 μm, a base layer thickness of 650 μm, a length of 250 mm, a hardness of 89, and a volume resistance value of 10 ⁵ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. Furthermore, the transfer efficiency was also evaluated. In the present invention, the transfer efficiency is a ratio indicating how much toner is transferred from the photosensitive member to the recording paper when the toner on the photosensitive member is transferred to the recording paper through the intermediate transfer member. In the present invention, this ratio is measured by the colorimetric density of the toner image. That is, the transfer efficiency is expressed as follows.

Transfer efficiency (%) = colorimetric density of toner image on recording paper ÷ colorimetric density of toner image on photoconductor × 100
The surface results are shown in Table 4. The transfer efficiency of the intermediate transfer member of Reference Example 1 was also measured and shown in Table 4.

[Example 2] <Surface modification by molybdenum disulfide>
An intermediate transfer member was prepared using the same material as in Example 1 except that 4 parts by weight of molybdenum disulfide was used in place of the RTFE particles. Molybdenum disulfide having an average particle diameter of 0.5 μm was used.

The obtained intermediate transfer member had a surface layer thickness of 100 μm, a base layer thickness of 900 μm, a length of 250 mm, a hardness of 93, and a volume resistance value of 10 ⁸ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[Reference Example 9]
(Formation of surface layer)
100 parts by weight of polyphenylsulfone as a binder was dissolved in a solvent DMAC so that the binder concentration was 5% by weight, and 8 parts by weight of conductive carbon (Ketjen Black 600JD) was added and dispersed for 30 minutes by a paint shaker. . This dispersion was put into the centrifugal molding machine shown in FIG. 2 and molded under conditions of 1500 RPM, 120 ° C. and 30 minutes.

(Creation of base layer)
A base layer was prepared using the same material as in Reference Example 1.

The obtained intermediate transfer member had a surface layer thickness of 10 μm, a base layer thickness of 900 μm, a length of 250 mm, a hardness of 92, and a volume resistance value of 10 ⁸ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 5.

[Comparative Example 1]
100 parts by weight of polyphenylsulfone is used as a binder, dissolved in a solvent DMAC so that the binder concentration is 20% by weight, and 8 parts by weight of conductive carbon (Ketjen Black 600JD) is added and dispersed for 30 minutes by a paint shaker. I let you. This dispersion is
The intermediate transfer member was obtained by carrying out dry molding under the conditions of 1500 RPM, 120 ° C., and 30 minutes.

The obtained intermediate transfer member had a film thickness of 150 μm, a length of 250 mm, and a volume resistance value of 10 ⁸ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 6.

  When an image was formed using this intermediate transfer member, an image was lost due to an increase in pressure during transfer.

[Comparative Example 2]
(Creation of base layer)
The base layer was made of polyurethane.

  100 parts by weight of polyol is heated to 80 ° C., 10 parts by weight of conductive carbon (Ketjen Black 600JD) is added and dispersed for 1 hour with a stirrer, and 60 parts by weight of isocyanate heated to 80 ° C. is added thereto, Disperse with a stirrer for 3 minutes. This dispersion was put into a centrifugal molding machine and heat-cured under the conditions of 2000 RPM, 120 ° C. and 3 hours. Thereafter, after aging was performed at 80 ° C. for 15 hours, the product was naturally cooled to room temperature, and the molded product was taken out from the molding machine and cut at the end.

(Formation of surface layer)
After 9 parts by weight of conductive carbon (Ketjen Black 600JD) was added to 100 parts by weight of polyethylene and dispersed with a hot roll, the surface was molded with a crosshead extruder. This and the base layer were heated and pressurized at 150 ° C. and bonded to obtain an intermediate transfer member.

The thickness of the surface layer was 130 μm, the thickness of the base layer was 700 μm, the length was 250 mm, and the volume resistance value was 10 ⁹ Ω · cm.

  This intermediate transfer member was evaluated in the same manner as in Reference Example 1. The results are shown in Table 7.

[Comparative Example 3]
100 parts by weight of polyol is heated to 80 ° C., 10 parts by weight of conductive carbon (Ketjen Black 600JD) is added and dispersed with a stirrer for 1 hour, and then 60 parts by weight of isocyanate heated to 80 ° C. is added thereto. Disperse with a stirrer for minutes. This dispersion was put into a centrifugal molding machine and heat-cured under the conditions of 2000 RPM, 120 ° C. and 3 hours. Then, after aging at 80 ° C. for 15 hours, naturally cooling to room temperature, taking out the molded product from the molding machine, cutting the end, spraying and drying the fluoroelastomer latex and drying the intermediate transfer member Obtained.

The obtained intermediate transfer member had a film thickness of 750 μm, a length of 250 mm, and a volume resistance value of 10 ⁸ Ω · cm.

  The intermediate transfer member was evaluated in the same manner as in Reference Example 1. As a result, the permanent elongation at the end of the evaluation test was 0.5% or less, and no void occurred. However, the intermediate transfer member was caused by the elastic elongation of the belt. As a result, it was found that toner misregistration during image formation occurred and color reproducibility was not good.

It is a perspective view showing an example of an intermediate transfer member of the present invention. It is a side view which shows an example of the centrifugal molding machine which manufactures the intermediate transfer body of this invention. 1 is a side view showing an example of an electrophotographic apparatus of the present invention. It is a front view which shows an example of a hollow image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 20 Intermediate transfer body 21 Base layer 22 Surface layer 72 Rotor 73 Heating fin 100 Image

Claims (6)

A base layer and a surface layer provided on the base layer, and the base layer is made of polyurethane, and the surface layer is made of polyphenylsulfone, polysulfone, polyethersulfone, polyester, polyacetal, polyarylate, polyamide, and polycarbonate. It is made of one of our engineering plastics,
On the surface layer, at least one of ETFE (ethylene-tetrafluoroethylene copolymer) or PTFE (polytetrafluoroethylene) fluorine resin powder, molybdenum disulfide, graphite, graphite fluoride, boron nitride, and silicone resin particles. An intermediate transfer member comprising a lubricant containing the intermediate transfer member.   The intermediate transfer member according to claim 1, wherein the hardness measured from the surface layer side is 40 to 100 degrees. The intermediate transfer member according to claim 1 or 2, wherein a conductive filler is contained in at least one of the base layer and the surface layer, and the volume resistivity in the thickness direction is 10 ⁵ -10 ¹² Ω · cm. The intermediate transfer member according to claim 3, wherein the volume resistivity is 10 ⁸ -10 ¹⁰ Ω · cm.   An electrophotographic photosensitive member; charging means for charging the electrophotographic photosensitive member; image exposing means for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image; and An electrophotographic apparatus comprising: a developing unit that develops and forms a toner image on the electrophotographic photosensitive member; and an intermediate transfer member to which the toner image is transferred. An electrophotographic apparatus comprising the intermediate transfer member according to claim 1. Rotating the cylindrical rotor, ETFE (ethylene-tetrafluoroethylene copolymer) or PTFE (polytetrafluoroethylene) fluororesin powder, molybdenum disulfide, graphite, graphite fluoride, nitriding on the inner surface of the rotor Contains a lubricant containing at least one of boron and silicone resin particles , and is made of engineering plastic of polyphenylsulfone, polysulfone, polyethersulfone, polyester, polyacetal, polyarylate, polyamide and polycarbonate And a step of forming a polyurethane base layer on the inner surface of the surface layer without removing the surface layer from the rotor.

Images