JP2005326470A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for surely forming a high quality image without generating the problem of a filming phenomenon or the like caused by a mold releasing agent by securing sufficient mold releasability in the image forming apparatus using a heat pressure fixing system. <P>SOLUTION: The image forming apparatus comprises a step of forming the image on one face of a recording material by performing image formation operation by an intermediate transfer body method, inverting and conveying the recording material to be introduced to a secondary transfer region, and setting an image formation mode forming the image on the other face of the recording material by performing image formation operation. A fixing means is composed of the heat pressure fixing system without having a mold releasing agent supply means, and provided with a recording material temperature detection means and a recording material cooling means operated in an operation condition corresponding to a detection result by the temperature detection means in a recording material inverting conveying passage from a fixing nip region in the fixing means to the secondary transfer region in the order to a conveying direction of the recording material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using, for example, an electrophotographic system.

At present, for example, in a certain type of image forming apparatus using an electrophotographic system, a toner image formed on an image forming body is temporarily transferred to an intermediate transfer body, and then secondarily transferred onto a recording material to perform the recording. An image is formed by a so-called intermediate transfer method in which an unfixed toner image formed on a material is fixed. An image forming apparatus using such an intermediate transfer method has an advantage that it has a high ability to cope with various recording materials such as cardboard.
As a method for fixing an unfixed toner image formed on a recording material, for example, a hot-pressure fixing system in which an unfixed toner image is fixed by heat and pressure is widely used.

A fixing device using such a heat-pressure fixing system is provided, for example, in such a manner that two fixing rotators are pressed against each other so as to form a fixing nip region, and an unfixed toner image is formed in this fixing nip region. The fixing process of the unfixed toner image is performed by passing the recording material. However, since the toner comes in contact with the surface of the fixing rotator, the fused toner adheres to the fixing rotator, thereby causing image smearing. (Offset phenomenon) or a recording material carrying a large amount of toner is easily caught in a fixing rotating body.
As a means for preventing such a problem from occurring, a release agent is applied to the surface of one fixing rotator that is in contact with an unfixed toner image, thereby separating the toner from the fixing rotator. Improving moldability has been done.

  As a release agent supplying means for applying and supplying a release agent to the surface of the fixing rotator, for example, in a state where a cleaning web impregnated with silicone oil is in contact with the surface of one fixing rotator. An arrangement (see, for example, Patent Document 1) or a heat-resistant fiber brush roller impregnated with silicone oil is arranged in contact with the surface of one fixing rotator, and is driven by one fixing rotator. Or a structure in which a release agent is supplied by rotating the heat-resistant fiber brush roller itself (see, for example, Patent Document 2) or an oil application roller in contact with one fixing rotator. The release agent is supplied in such a manner that it is driven by one fixing rotator or by rotationally driving the oil application roller itself. (For example see Patent Document 3.) And the like are known.

On the other hand, as means for improving the releasability between the toner and one fixing rotator, it is widely practiced to impart releasability to the toner itself by adding a release agent to the toner. . This is because when the toner is melted in the fixing nip, the release agent oozes out between the toner resin and one fixing rotator, thereby increasing the adhesion between the one fixing rotator and the toner resin. This is to prevent the occurrence of an offset phenomenon or a recording material entrainment phenomenon.
JP 2002-258657 A JP-A-7-104602 JP-A-9-166933

Thus, in such a fixing process by the hot-pressure fixing method, from the viewpoint of the separability (release property) of the fixing rotator, a large amount of release agent is present between the toner resin and the fixing rotator. Is more preferable.
However, when the fixing process is performed in a state where a large amount of release agent is present between the toner resin and the fixing rotator, a fixed image is formed on one side when an image is formed on both sides of the recording material. The release agent adhering to the recorded material may be transported to the secondary transfer area, and as a result, the release agent adheres to the surface of the intermediate transfer member, and the release agent adheres to the intermediate transfer member. There is a problem that a filming phenomenon occurs due to rubbing by a cleaning member such as a provided cleaning blade, and it becomes difficult to form an image with high image quality. For example, when a wax that solidifies at room temperature is used as a mold release agent, the filming phenomenon is less likely to occur than when, for example, silicone oil that is liquid at room temperature is used. When the wax adhering to the recording material on which the fixed image is formed on one side is conveyed to the secondary transfer area in a state where it is not sufficiently solidified, the same problem eventually occurs.
Such a problem is that the time required from passing through the fixing nip area to the secondary transfer area (contacting the intermediate transfer member) is short, that is, for example, the higher the process speed, the harder the wax is solidified. It becomes noticeable. From the viewpoint of fixing properties, it is preferable to set the fixing temperature high, but such a problem becomes more prominent as the fixing temperature is set higher.

To solve such problems, for example, it is conceivable that a polishing means is provided on the intermediate transfer member, and the release agent adhering to the surface of the intermediate transfer member is removed by the polishing means. However, the surface of the intermediate transfer member is polished. Therefore, the method of maintaining the original performance of the intermediate transfer member has a problem that the service life of the intermediate transfer member is shortened.
Further, in the fixing device provided with the release agent supply means, it is possible to suppress the occurrence of the above problems by reducing the supply amount of the release agent to the heating rotator, but it is not sufficient. Is the actual situation.

  The present invention has been made based on the above circumstances, and in an image forming apparatus provided with a fixing device by a hot-pressure fixing method, sufficient releasability is ensured, and on both sides of a recording material. An object of the present invention is to provide an image forming apparatus capable of reliably forming a high-quality image over a long period of time without causing a problem such as a filming phenomenon caused by a release agent when forming an image. .

The image forming apparatus according to the present invention provides an intermediate transfer member that moves a toner image formed on a rotating image forming member while contacting a surface of the image forming member provided with a cleaning member in contact with the surface. Secondary transfer means provided so as to form a primary transfer toner image by primary transfer on the primary transfer means, and to form a secondary transfer area by pressing the primary transfer toner image against the surface of the intermediate transfer member To form a secondary transfer toner image by secondary transfer onto the recording material, and to form an image by thermally fixing the secondary transfer toner image formed on the recording material by a fixing means. As a result, an image is formed on one surface of the recording material, and the recording material on which the image is formed on the one surface is reversely conveyed and introduced into the secondary transfer region, and the image forming operation is performed to perform the other recording material. In the image forming apparatus image forming mode is set for forming an image on,
As the toner, a toner containing a release agent is used,
The fixing means is arranged such that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material It does not have a release agent supply means to apply and supply a release agent to
A temperature detection means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip area to the secondary transfer area, and a position downstream of the temperature detection means in the recording material conveyance direction. In addition, a recording material cooling means that is operated under operating conditions according to the detection result of the temperature detection means is provided.

Further, the image forming apparatus of the present invention is an intermediate in which a toner image formed on a rotating image forming body is moved while being in contact with the image forming body provided with a cleaning member in contact with the surface. A primary transfer toner image is formed on the transfer body by primary transfer by a primary transfer means, and a secondary transfer area is formed by pressing the primary transfer toner image against the surface of the intermediate transfer body. Image forming operation in which a secondary transfer toner image is formed by secondary transfer onto a recording material by a transfer means, and an image is formed by thermally fixing the secondary transfer toner image formed on the recording material by a fixing means. By forming the image, an image is formed on one surface of the recording material, and the recording material having the image formed on the one surface is reversely conveyed and introduced into the secondary transfer region, and the recording operation is performed by performing the image forming operation. In the image forming apparatus image forming mode is set to form an image on the other surface of,
As the toner, a toner containing a release agent is used,
The fixing means is arranged such that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material It does not have a release agent supply means to apply and supply a release agent to
A temperature detecting means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip region to the secondary transfer region, and is downstream of the cleaning member contact position in the moving direction of the intermediate transfer member. A polishing means for polishing the surface of the intermediate transfer member, which is operated under an operating condition corresponding to a detection result by the temperature detection means, is provided at a position on the side.

Further, the image forming apparatus according to the present invention provides a toner image formed on the rotated image forming body, which is provided with the cleaning member in contact with the surface and moves while being in contact with the image forming body. A primary transfer toner image is formed on the transfer body by primary transfer by a primary transfer means, and a secondary transfer area is formed by pressing the primary transfer toner image against the surface of the intermediate transfer body. Image forming operation in which a secondary transfer toner image is formed by secondary transfer onto a recording material by a transfer means, and an image is formed by thermally fixing the secondary transfer toner image formed on the recording material by a fixing means. In addition to forming an image on one surface of the recording material, the recording material having the image formed on the one surface is reversely conveyed and introduced into the secondary transfer area, and the image forming operation is performed. In the image forming apparatus image forming mode is set to form an image on the other surface of the wood,
As the toner, a toner containing a release agent is used,
The fixing means is arranged such that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material It does not have a release agent supply means to apply and supply a release agent to
The recording material cooling means is provided in the recording material reversal conveyance path from the fixing nip area to the secondary transfer area, and the recording material cooling means is operated under an operating condition corresponding to the fixing condition and the process speed. To do.

Further, the image forming apparatus of the present invention is an intermediate in which a toner image formed on a rotating image forming body is moved while being in contact with the image forming body provided with a cleaning member in contact with the surface. A primary transfer toner image is formed on the transfer body by primary transfer by a primary transfer means, and a secondary transfer area is formed by pressing the primary transfer toner image against the surface of the intermediate transfer body. Image forming operation in which a secondary transfer toner image is formed by secondary transfer onto a recording material by a transfer means, and an image is formed by thermally fixing the secondary transfer toner image formed on the recording material by a fixing means. By forming the image, an image is formed on one surface of the recording material, and the recording material having the image formed on the one surface is reversely conveyed and introduced into the secondary transfer region, and the recording operation is performed by performing the image forming operation. In the image forming apparatus image forming mode is set to form an image on the other surface of,
The fixing unit is arranged so that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material A release agent supply means for applying and supplying the release agent to
A temperature detection means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip area to the secondary transfer area, and a position downstream of the temperature detection means in the recording material conveyance direction. In addition, a recording material cooling means that is operated under operating conditions according to the detection result of the temperature detection means is provided.

Further, the image forming apparatus according to the present invention provides a toner image formed on the rotated image forming body, which is provided with the cleaning member in contact with the surface and moves while being in contact with the image forming body. A primary transfer toner image is formed on the transfer body by primary transfer by a primary transfer means, and a secondary transfer area is formed by pressing the primary transfer toner image against the surface of the intermediate transfer body. Image forming operation in which a secondary transfer toner image is formed by secondary transfer onto a recording material by a transfer means, and an image is formed by thermally fixing the secondary transfer toner image formed on the recording material by a fixing means. In addition to forming an image on one surface of the recording material, the recording material having the image formed on the one surface is reversely conveyed and introduced into the secondary transfer area, and the image forming operation is performed. In the image forming apparatus image forming mode is set to form an image on the other surface of the wood,
The fixing unit is arranged so that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material A release agent supply means for applying and supplying the release agent to
A temperature detecting means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip region to the secondary transfer region, and is downstream of the cleaning member contact position in the moving direction of the intermediate transfer member. A polishing means for polishing the surface of the intermediate transfer member, which is operated under an operating condition corresponding to a detection result by the temperature detection means, is provided at a position on the side.

According to the image forming apparatus of the present invention, basically, a fixing device that does not have a releasing agent supply unit is used and toner containing the releasing agent is used, so that the consumption of the releasing agent is increased. Although the amount is set to be as small as possible, sufficient releasability and sufficient fixing properties can be obtained, and the occurrence of an offset phenomenon can be reliably prevented.
In addition, when forming an image on both sides of the recording material, the temperature of the recording material on which the fixed image is formed on one side is detected, and the recording material cooling means is operated under an operating condition adjusted based on the detection result. Accordingly, since the recording material is introduced into the secondary transfer region and the secondary transfer process is performed in a state where the release agent related to the toner constituting the fixed image on the recording material is solidified, the release agent is intermediate Adherence to the transfer member and the secondary transfer unit is reliably prevented, and therefore, a filming phenomenon caused by the release agent does not occur, and a high-quality image can be reliably formed. .
In addition, a fixing device having a release agent supply unit is used, and the image forming apparatus has a configuration in which the release agent is supplied to one fixing rotating body that contacts the secondary transfer toner image by the release agent supply unit Similar effects can be obtained in the apparatus.

In addition, according to the image forming apparatus of the present invention, basically, a fixing device that does not have a releasing agent supply unit is used and a toner containing a releasing agent is used, so that the releasing agent is used. However, it is possible to obtain a sufficient release property and a sufficient fixing property and reliably prevent the occurrence of an offset phenomenon.
Moreover, when forming an image on both sides of the recording material, the toner constituting the fixed image on the recording material from the fixing nip region to the secondary transfer region after the recording material having the fixed image formed on one surface is formed. In a state where the release agent according to the state cannot be sufficiently solidified, it is introduced into the secondary transfer region, and even when the release agent adheres to the surface of the intermediate transfer member, The original performance of the intermediate transfer member can be maintained by polishing the surface of the intermediate transfer member by the polishing means, and the temperature of the recording material on which the fixed image is formed is detected, and based on the detection result By operating the polishing means under the adjusted operating conditions, the intermediate transfer member is not excessively polished, and the required polishing effect can be obtained without significantly reducing the service life of the intermediate transfer member. In , Therefore, release agent without problems such as filming occurs due, it is possible to stably form over a long period of time with high quality image.
Also, a fixing device having a release agent supply means is used, and the supply amount of the release agent to one fixing rotating body in contact with the secondary transfer toner image by the release agent supply means is as small as possible The same effect can be obtained also in the image forming apparatus set to 1.

  According to the image forming apparatus of the present invention, the detection obtained by actually detecting the temperature of the recording material also by operating the recording material cooling means or the polishing means under the operating conditions corresponding to the fixing process condition and the process speed. The same effect as when operating conditions are controlled based on the result can be obtained.

<First Embodiment>
FIG. 1 is an explanatory diagram showing an outline of the configuration of an example of a color image forming apparatus according to the present invention.
In this color image forming apparatus, an endless intermediate transfer belt 20 as an intermediate transfer member and a toner image forming unit arrangement region in the intermediate transfer belt 20 are separated from each other with respect to the moving direction of the intermediate transfer belt 20. Four toner image forming units 10Y, 10M, 10C, and 10K provided in a line are provided, and the intermediate transfer belt 20 is a primary transfer roller 15A in each of the four toner image forming units 10Y, 10M, 10C, and 10K. Thus, the plurality of support roller groups 21A, 21B, 21C, and 21D are stretched so as to be circulated and moved in contact with each of the photoconductors 11, 11, 11, and 11 that are image forming bodies. Yes.

  The intermediate transfer belt 20 is made of a resin material such as polycarbonate (PC), polyimide (PI), polyamideimide (PAI), polyvinylidene fluoride (PVDF), tetrafluoroethylene-ethylene copolymer (ETFE), ethylene- A rubber material such as propylene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), polyurethane rubber, or the like, in which a conductive filler such as carbon is dispersed, or an ionic conductive material is contained. Can be used.

A toner image forming unit 10 </ b> Y related to a yellow toner image includes a drum-shaped photoreceptor 11 that is rotated. An exposure means 13 as a means and a development means 14 for developing with a developer containing yellow toner are arranged in order of operation, and are downstream of the development region by the development means 14 with respect to the rotation direction of the photosensitive member 11. At this position, a primary transfer roller 15A for transferring a yellow toner image formed on the photoconductor 11 to the intermediate transfer belt 20 by applying an appropriate transfer electric field is pressed against the photoconductor 11 via the intermediate transfer belt. Thus, the primary transfer region T1 is formed, and thereby the primary transfer means 15 is configured. In FIG. 1, reference numeral 16 denotes a photoconductor cleaning device for removing untransferred toner remaining on the photoconductor 11 after passing through the primary transfer region T1.
Each of the other toner image forming units 10M, 10C, and 10K has the same configuration as the toner image forming unit 10Y related to the yellow toner image.

  At a position downstream of the toner image forming unit arrangement region in the moving direction of the intermediate transfer belt 20, the secondary transfer roller 25A is pressed against the support roller 21A via the intermediate transfer belt 20 to form a secondary transfer region T2. For example, a transfer bias controlled to an appropriate magnitude is applied by a bias applying means (not shown) connected to the support roller 21A to form a transfer electric field in the secondary transfer region T2, Thus, a contact transfer type secondary transfer means 25 is configured to transfer the color toner image on the intermediate transfer belt 20 onto the recording material P supplied from the recording material supply unit 18.

An unfixed color toner image (secondary transfer toner image) formed on the recording material P is fixed at a position downstream of the secondary transfer region T2 in the conveyance direction (indicated by an arrow in the drawing) of the recording material P. Fixing means is provided.
The fixing unit is arranged in such a manner that two fixing rotators are in pressure contact with each other so as to form a fixing nip region, and a heating source is provided inside at least one fixing rotator. A pressure fixing type is used. Specifically, as shown in FIG. 2, for example, a heating roller 31 having a heating source 35A disposed therein and a pressure applied to the heating roller 31 are used. The fixing roller 30 includes two fixing rotators each including a pressure roller 36 disposed so as to form a fixing nip region N.
This fixing device 30 does not have a release agent supplying means for applying a release agent to the surface of the heating roller 31 that contacts the unfixed toner image on the recording material P.

The heating roller 31 is formed on a cylindrical cored bar 32 made of metal and extending on the surface of the cored bar 32, extending in the width direction of the recording material P being conveyed (in FIG. 1, the direction perpendicular to the paper surface). And a release layer 34 made of, for example, a fluororesin, formed on the surface of the elastic layer 33. Inside the metal core 32, a heating made of, for example, a rod-shaped halogen heater lamp is provided. A source 35 </ b> A is arranged to extend in the axial direction of the cored bar 32.
The metal constituting the metal core 32 is not particularly limited, and various metals can be used. Specific examples thereof include metals such as aluminum, iron, and copper, or alloys thereof.
The outer diameter and thickness of the cored bar 32 have a sufficient mechanical strength, but the outer diameter of the cored bar 32 is, for example, 20 to 65 mm from the viewpoint of reducing power consumption by reducing the heat capacity. It is preferable that the thickness of the cored bar 32 is, for example, 0.5 to 5.0 mm.
The elastic body constituting the elastic layer 33 is not particularly limited, and examples thereof include various heat-resistant soft rubbers and sponge rubbers such as fluorine rubber and silicone rubber.
The thickness and the hardness of the elastic layer 33 are, for example, 0.5 mm from the viewpoint of uniformly supplying thermal energy to the unfixed toner image by increasing the adhesion to the recording material P. The hardness of the elastic layer 33 is, for example, preferably a JIS-A hardness of 1 to 20, more preferably 5 to 10.
Examples of the fluororesin constituting the release layer 34 include polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene (PFA), and a copolymer of tetrafluoroethylene and hexafluoropropylene. (FEP) can be exemplified.
The thickness of the release layer 34 is preferably 20 to 50 μm, for example.

The pressure roller 36 includes a cylindrical cored bar 37 made of, for example, metal, an elastic layer 38 formed on the surface of the cored bar 37, and a release layer 39 formed on the surface of the elastic layer 38. A heating source 35B made of, for example, a rod-shaped halogen heater lamp is disposed in the core bar 37 so as to extend in the axial direction of the core bar 37.
Here, as materials constituting the metal core 37, the elastic layer 38, and the release layer 39, those exemplified as those constituting the heating roller 21 can be used.
The core metal 37 constituting the pressure roller 36 preferably has an outer diameter of, for example, 18 to 60 mm and a thickness of, for example, 0.5 to 5.0 mm.
The elastic layer 38 constituting the pressure roller 36 preferably has a thickness of, for example, 0.5 to 3.0 mm and a JIS-A hardness of, for example, 1 to 20.
The thickness of the release layer 39 is preferably 20 to 50 μm, for example.

  At a position downstream of the secondary transfer region T2 in the movement direction of the intermediate transfer belt 20, the leading edge is disposed so as to extend in the width direction of the intermediate transfer belt 20 in a state where it abuts against the surface of the intermediate transfer belt 20, for example. An intermediate transfer body cleaning device 27 having a blade cleaning mechanism having a plate-like intermediate transfer body cleaning blade (hereinafter also simply referred to as “cleaning blade”) 26 made of an elastic body such as urethane rubber is provided.

  In this image forming apparatus, when images are formed on both sides of the recording material P, a recording material in which a fixed image C is formed on one side by performing a series of image forming operations (hereinafter referred to as “fixed image carrying recording material”). A reversal conveyance mechanism 40 is provided for introducing the fixed image carrying recording material S into the secondary transfer region T2 with the other side of S facing the image carrying surface of the intermediate transfer belt 20. In FIG. 1, reference numeral 41 denotes a reverse conveyance path in which the fixed image carrying recording material S is conveyed with one surface on which the fixed image C is formed facing upward.

In the image forming apparatus described above, when forming an image on the downstream side of the fixing nip region N in the conveyance direction of the recording material P, specifically, on both sides of the recording material P, the fixed image carrying recording material S is introduced. A temperature detecting means 45 for detecting the surface temperature of the other surface of the fixed image carrying recording material S is disposed in the reversing conveyance path 41, and the fixed image carrying recording material S is conveyed in the reversing conveyance path 41. A recording material cooling means 50 for cooling the fixed image carrying recording material S is arranged at a position downstream of the arrangement position of the temperature detecting means 45 in the direction.
Even if the temperature detection means 45 is provided in a state of detecting the temperature of the position where the fixed image C is formed in the width direction of the fixed image carrying recording material S, it detects the temperature of the positions on both sides of the fixed image C. Or any of them may be provided.

  The temperature detecting means 45 is constituted by a non-contact type temperature detecting element such as “NC sensor” manufactured by Ishizuka Electronics or “thermopile infrared sensor” manufactured by PerkinElmer. By using a non-contact type temperature detecting element, even if the fixed image C formed on one surface is in a state where the release agent is cooled and not solidified, the fixed image C is disturbed. Temperature detection can be performed without causing image defects.

  As shown in FIG. 3, the recording material cooling means 50 is provided so as to extend in a direction perpendicular to the conveying direction of the fixed image carrying recording material S (direction perpendicular to the paper surface in FIG. 1). For example, the cooling cylindrical member 51 made of a material having high thermal conductivity such as metal and the cooling cylindrical member 51 are mutually connected in the end region other than the fixed image carrying recording material passage region R in the cooling cylindrical member 51. The plurality of heat conducting members 52 made of, for example, plate-like fins provided so as to extend along the conveying direction of the fixed image carrying recording material S in a state of being separated in the longitudinal direction of A cooling air supply means 53 such as a fan for supplying cooling air is provided, and a fixed image carrying recording material passage region R formed on, for example, the upper surface of the cooling cylindrical member 51 has a pair of roller members. 5 A belt-like member 55 supported in a stretched state by A and 54B is provided so as to contact and travel along the outer peripheral surface of the cooling cylindrical member 51, whereby the cooling cylindrical member is provided. A cooling region L having a predetermined size is formed in the circumferential direction 51. It is more preferable that the cooling tubular member 51 includes a heat pipe.

  The size of the cooling region L in the recording material cooling means 50 (the circumferential length on the surface of the cooling cylindrical member 51) depends on the fixing process conditions such as the fixing temperature and the process speed, or the configuration of the cooling cylindrical member 51. For example, it is preferably 5 mm or more, and more preferably 10 to 20 mm, although it varies depending on the like. If the size of the cooling region L is 5 mm or more, a cooling effect can be obtained, but if it is 10 mm or more, a sufficient cooling effect can be reliably obtained.

The cooling air supply means 53 is configured to supply, for example, air in the external environment of the image forming apparatus as cooling air, and the operating state of the surface of the fixed image carrying recording material S detected by the temperature detection means 45 is used. On the basis of the output value, the supply amount of the cooling air to the heat conduction member 52 is adjusted.
Specifically, when an image is formed on the other surface of the fixed image carrying recording material S, the surface temperature of the fixed image carrying recording material S is equal to or lower than the temperature t1 in the DSC curve of the release agent described later, more preferably the temperature t2 ( <T1) The operation state of the cooling air supply means 53 is controlled so as to be introduced into the secondary transfer region T2 in the state set as follows.

  As the color toners used in the image forming apparatus according to the present invention having the fixing device 30 that does not have the above-described release material application means, toner particles containing a release agent are used.

As the release agent, for example, paraffin wax, polyolefin wax, modified products thereof (for example, oxides and grafted products), higher fatty acids, and metal salts thereof, amide waxes, ester waxes and the like are conventionally used. The wax etc. which are used suitably can be illustrated.
The content of the release agent in the toner is preferably, for example, 1 to 30% by mass, more preferably 2 to 20% by mass, and still more preferably 3 to 15% by mass.

  It is preferable that melting | fusing point of a mold release agent is 60-110 degreeC, More preferably, it is 70-90 degreeC. According to the release agent having a melting point in the range of 60 to 110 ° C., it is possible to lower the overall melt viscosity of the obtained toner, and to improve the fixability to the recording material. When the melting point of the release agent is less than 60 ° C., the fixability itself is improved, but the storability of the toner is lowered and toner blocking is liable to occur, causing a problem in practical use. On the other hand, when the melting point exceeds 110 ° C., the melting start temperature becomes high, so that the contribution to the improvement of the fixing property is low, and it becomes difficult to obtain sufficient releasability.

Here, the “melting point of the release agent” means that the temperature is raised from 0 ° C. to 200 ° C. under the condition of 10 ° C./min (first temperature raising process) with a differential calorimeter (DSC), The DSC curve measured when left at 200 ° C. for 1 minute and then cooled to 0 ° C. at 10 ° C./min (first cooling process) shows the maximum endothermic peak in the first temperature rising process. Refers to temperature.
Further, as shown in FIG. 4, in the DSC curve in the first cooling process, the temperature showing the maximum peak of the exothermic peak in the first cooling process is t1, and the curve portion on the temperature side lower than the temperature t1 in the DSC curve Let t2 be the temperature at the intersection of the tangent TL and the base line BL at the point where the differential value with respect to the temperature becomes maximum. Here, the temperature difference between the temperature t1 and the temperature t2 varies depending on the type of the release agent used, but is preferably 20 ° C. or less, for example.

  Moreover, it is preferable that a mold release agent is a penetration of 4 or less in 25 degreeC measured based on JISK-2235-5.4. When the penetration exceeds 4, the release agent solidified by friction generated in the secondary transfer region T2 may move (attach) to the intermediate transfer belt 10 or the secondary transfer roller 25A.

It is preferable that the mold release agent has an endothermic peak in the first temperature rising process in the DSC curve at 60 to 110 ° C, particularly 70 to 90 ° C.
Moreover, it is preferable that a mold release agent has the exothermic peak in the 1st cooling process in a DSC curve in 50-100 degreeC, especially 60-90 degreeC.
Here, the relationship of endothermic peak ≧ exothermic peak is established for both the endothermic peak and the exothermic peak. The temperature difference between the endothermic peak and the exothermic peak is not particularly limited, but is preferably 30 ° C. or less.

  The toner used in the image forming apparatus having the above configuration preferably has an average value (average circularity) of the shape factor (circularity) represented by the following formula 1 of 0.94 to 0.97.

  By using a toner having an average circularity of 0.94 to 0.97, the shape of the toner can be made amorphous to some extent, and thus heat can be transferred with high efficiency and fixing ability. In addition, sufficient transferability can be obtained without degrading the cleaning performance.

  The number average particle diameter of the toner is preferably, for example, 3 to 9 μm, more preferably 4.5 to 7.5 μm, and still more preferably 5 to 7 μm.

The toner having such a shape can be obtained by granulation polymerization, for example.
The granulated polymerization toner means a toner obtained by forming a toner binder resin and forming the toner shape by polymerization of a raw material monomer or prepolymer of the binder resin and subsequent chemical treatment. It means a toner obtained through a polymerization reaction such as polymerization or emulsion polymerization and, if necessary, a step of fusing particles between them. Such a granulated polymerized toner is obtained by uniformly dispersing a raw material monomer or prepolymer in an aqueous system and then polymerizing it, so that the toner has a uniform particle size distribution and shape.
These methods are not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904.

In the above image forming apparatus, an image forming operation is performed as follows.
That is, in the toner image forming unit 10Y related to yellow toner, for example, the surface of the rotating photoreceptor 11 is sequentially charged to a predetermined polarity (for example, negative polarity) by the charging unit 12, and in this state, the photoreceptor 11 By selectively irradiating the surface with light by the exposure means 13, the potential of the irradiated portion (exposure area) is lowered, and an electrostatic latent image is formed with a dot pattern corresponding to the original image.
On the other hand, a developing bias having the same polarity (for example, negative polarity) as the surface potential of the photoreceptor 11 is applied to the surface of the developing sleeve 141 constituting the developing unit 14 from a power source (not shown), and is the same as the surface potential of the developing sleeve 141. A developer containing toner charged with polarity (for example, negative polarity) is transported to the development region in a state where the transport amount is regulated. In the developing area, the toner on the developing sleeve 141 adheres to the exposed area of the photoconductor 11 and reverse development is performed, so that a toner image is formed on the photoconductor 11.
Such an image forming operation is performed in the toner image forming units 10M, 10C, and 10K related to the toners of the respective colors, and the toner images of the respective colors are formed on the photoreceptor 11 in the respective toner image forming units 10M, 10C, and 10K. The

  Each color toner image formed in each of the toner image forming units 10Y, 10M, 10C, and 10K is sequentially primary transferred onto the intermediate transfer belt 20 in each primary transfer region T1, and each color is transferred onto the intermediate transfer belt 20. A color toner image is formed by superimposing these toner images, and this color toner image is conveyed to the secondary transfer region T2 while being carried on the intermediate transfer belt 20, and in the secondary transfer region T2, the secondary transfer is performed. By the action of the transfer electric field formed by the roller 25A and the support roller 21A, the recording material P conveyed along the conveyance path in a state synchronized with the color toner image carried on the intermediate transfer belt 20 is applied. After the secondary transfer, the image is formed on one surface of the recording material P by fixing with heat and pressure by the fixing device 30. Note that, by selectively using the toner image forming unit 20K relating to black toner, for example, a monochrome image using only black toner is formed.

  On the other hand, in each of the toner image forming units 10Y, 10M, 10C, and 10K, the untransferred toner remaining on the photoconductor 11 that has passed through the primary transfer region T1 is removed by the photoconductor cleaning device 16 and also the secondary. Untransferred toner remaining on the intermediate transfer belt 10 that has passed through the transfer region T2 is mechanically removed by the cleaning blade 26 in the intermediate transfer body cleaning device 27.

Further, when an image is formed on the other surface of the recording material (fixed image carrying recording material S) on which the fixed image C is formed by performing the series of image forming operations as described above, fixing by the fixing device 30 is performed. After the processing is performed, the temperature detection unit 45 detects the surface temperature of the other surface of the fixed image carrying recording material S that is introduced into the reverse conveyance path 41, and the temperature detection unit 45 performs the detection of the fixed image carrying recording material S. The fixed image carrying recording material S is cooled as required by the recording material cooling means 50 controlled to an appropriate operation state based on the output value relating to the surface temperature. Here, “if necessary” is used when the surface temperature of the fixed image carrying recording material S is, for example, about 1 to 20 ° C. higher than the temperature t1 in the DSC curve of the release agent. The temperature at which the release agent relating to the toner constituting the fixed image C in the fixed image carrying recording material S can be sufficiently solidified until the fixed image carrying recording material S is introduced into the secondary transfer region T2. This is because the cooling air supply means 53 may not be operated. This condition is determined by the conveyance speed of the recording material.
Specifically, when the detected surface temperature of the fixed image carrying recording material S is higher than the temperature t1 related to the release agent, the cooling air supply means 53 is operated to adjust the cooling air to an appropriate size. By supplying the heat supply member 52 with the supplied amount, the cooling cylindrical member 51 is maintained in a state sufficiently lower than the temperature of the fixed image carrying recording material S, and the fixed image carrying is carried. When the recording material S passes through the cooling region L on the surface of the cooling cylindrical member 51, the recording material S is radiated and cooled to a temperature state lower than the temperature t1 related to the release agent.

  Then, the sufficiently cooled fixed image carrying recording material S is introduced into the secondary transfer region T2, and the secondary transfer process by the secondary transfer unit 25 and the fixing process by the fixing device 30 are sequentially performed, thereby fixing the fixed image. An image is formed on the other surface of the carrier recording material S.

  Thus, according to the above-described image forming apparatus, it is possible to reliably prevent the occurrence of an offset phenomenon without using a release agent such as silicone oil for the heating roller 31 in the fixing device 30. In addition, when forming images on both sides of the recording material P, the temperature of the fixed image carrying recording material S is detected by the temperature detecting means 45, and the recording material cooling means 50 is operated under the operating conditions adjusted based on the detection result. By being actuated, the fixed image carrying recording material S is introduced into the secondary transfer region T2 in a state where the release agent relating to the toner constituting the fixed image C in the fixed image carrying recording material S is sufficiently solidified. Therefore, the release agent is reliably prevented from adhering to the intermediate transfer belt 20 and the secondary transfer roller 25A. Without problems such as filming phenomenon occurs that, a high quality image can be reliably formed.

Therefore, according to the present invention, since the amount of toner (the amount of the release agent) constituting the fixed image C formed on the recording material P is large, the above problem, that is, the release agent adheres to the intermediate transfer belt 20. This is extremely useful in a color image forming apparatus in which the accompanying filming phenomenon easily occurs.
Further, from the viewpoint of improving the fixability, when the fixing temperature is set to 180 ° C. or higher, or when the process speed is set to 200 mm / sec or more in response to a request for high speed, the secondary temperature from the fixing nip region N The present invention is extremely useful when the time required to reach the transfer region T2 is extremely short.

In the above embodiment, a fixing device that does not have a releasing agent supply means is used, and a toner containing a releasing agent is used as a toner, thereby improving the releasing property and fixing property. The image forming apparatus is described, but a color image having a structure in which the release property and the fixability are improved by using a toner containing no release agent and using a fixing device having a release agent supply means. The present invention can be applied to a forming apparatus.
Specifically, in such a color image forming apparatus, an unfixed toner image on a recording material as shown in FIG. 5, for example, is formed as fixing means in the color image forming apparatus shown in FIG. 1 having the same configuration as that of the image forming apparatus shown in FIG. 1 except that a fixing device provided with a release agent supply means for applying and supplying a release agent to one fixing rotator is used. It is. In FIG. 5, the same components as those of the fixing device shown in FIG.

  The release agent supply means 60 in the fixing device 30A is provided in pressure contact with the heating roller 31 at a position upstream of the fixing nip region N in the rotation direction of the heating roller 31 (indicated by an arrow in the drawing). An external heating rotator 61 that is driven by the heating roller 31 or driven by an appropriate driving means and rotated so as to move in the same direction as the peripheral surface of the heating roller 31 at a pressure contact position with the heating roller 31; A long sheet-like web 65 is provided so as to run while being in contact with the outer peripheral surface of the external heating rotator 61, and a conveying means for conveying the web 65.

  The conveying means for conveying the web 65 is indicated by a main winding portion 66 having a rotatable main winding shaft 66A around which a web 65 impregnated with a release agent is wound, and a clockwise direction (indicated by an arrow in the figure) by a driving source. ) And a winding portion 67 having a winding shaft 67 </ b> A rotated, and these constituent members are connected to the external heating rotator 61 on the path from the web 65 to the winding portion 67. A release agent application region W is formed in the release agent application region W so that the traveling direction of the web 65 is the same as the moving direction of the surface of the external heating rotator 61.

  The circumferential length of the external heating rotator 61 in the release agent supply region W is preferably, for example, 10 mm or more. If this length is too small, the release agent supplied from the web 65 to the external heating rotator 61 cannot be reliably applied to the surface of the heating roller 31. In addition, the axial width in the release agent application region W is preferably equal to or greater than the maximum width of the recording material P. As a result, regardless of the size of the recording material P, sufficient releasability and sufficient fixability can be reliably obtained.

The conveying speed of the web 65 by the conveying means is preferably in the range of, for example, 0.04 to 0.20 mm / copy (when A3 paper is vertically fed).
When the conveyance speed of the web 65 is 0.04 mm / copy or more, the release agent is reliably applied to the external heating rotator 61, and by setting the web 65 to 0.20 mm / copy or less, the service life of the web 65 is reduced. The length of the web 65 can be increased, thereby providing an advantage in terms of cost, and the necessity of using a very long web 65 is reduced, so that the accommodation space of the web 65 can be reduced. it can.

The web 65 constituting the release agent supply means 60 is formed by impregnating a release agent into a release agent impregnation material such as a nonwoven fabric containing aromatic polyamide and / or polyester.
As the release agent to be impregnated into the web 65, those exemplified as the release agent constituting the above-described toner can be used.

  In the fixing device provided with such a release agent supply means 60, the surface temperature of the web 65 in the release agent supply region W is set to be an external heating rotator by using a release agent having a melting point of 60 to 110 ° C. 61 makes the state higher than the melting point of the release agent, so that the release agent is smoothly melted in the release agent supply region W, and the supply efficiency of the release agent from the web 65 to the external heating rotor 61 is improved. Can be made.

As the external heating rotator 61, a coating layer 63 is formed on the outer peripheral surface of a cylindrical metal core 62 made of metal, for example, and a heating source 64 such as a halogen heater lamp is disposed inside the metal core 62. Can be used.
The external heating rotator 61 is rotated, for example, in a state where the outer peripheral speed is the same as that of the heating roller 31. The external heating rotator 61 is rotated in this state and the web 65 is transported at the transport speed described above, whereby the external heating rotator 61 and the web 65 are transported in the release agent supply region W. As a result, the web 65 is rubbed, whereby the molten release agent impregnated in the web 65 can be reliably supplied to the external heating rotator 61.
The external heating rotator 61 is in contact with the heating roller 31 with a load of 19.6 to 98N. Thereby, the mold release agent on the external heating rotator 61 can be applied to the heating roller 31 in a state adjusted to an appropriate amount.

  A part of the release agent applied to the heating roller 31 by the release agent supply means 60 adheres to the surface of the recording material S. When an image is formed on the other surface of the fixed image carrying recording material S, The release agent adhering to the surface of the fixed image carrying recording material S is solidified by the action of the recording material cooling means 50, and the fixed image carrying recording material S is introduced into the secondary transfer region T2 in this state. It is possible to suppress the occurrence of a filming phenomenon caused by the release agent attached to the next transfer roller 25A and the intermediate transfer belt 20.

According to the image forming apparatus having the above configuration, the same operations and effects as those of the image forming apparatus having the configuration shown in FIG. 1 can be obtained. That is, the fixing device 30A having the release agent supply unit 60 is used, and the release agent is supplied to the heating roller 31 by the release agent supply unit 60. Fixability can be obtained, and the occurrence of an offset phenomenon can be reliably prevented.
In addition, when forming images on both sides of the recording material P, the temperature of the fixed image carrying recording material S is detected by the temperature detecting means 45, and the recording material cooling means 50 operates under the operating conditions adjusted based on the detection result. As a result, the fixed image carrying recording material S is introduced into the secondary transfer region T2 in a state where the release agent attached to the surface of the fixed image carrying recording material S is sufficiently solidified, and the secondary transfer process is performed. As a result, the release agent is reliably prevented from adhering to the intermediate transfer belt 20 and the secondary transfer roller 25A. Therefore, problems such as a filming phenomenon caused by the release agent do not occur. An image with high image quality can be reliably formed.

Second Embodiment
The image forming apparatus according to the second embodiment of the present invention cools the recording material on which the fixed image is formed on one side when the image is formed on both sides of the recording material in the image forming apparatus according to the first embodiment. By providing a cooling means, the release agent relating to the toner constituting the fixed image formed on one surface of the recording material is prevented from adhering to the surface of the intermediate transfer member, thereby preventing the occurrence of filming phenomenon. Instead, by providing a polishing means for polishing the surface of the intermediate transfer member, when the release agent adheres to the surface of the intermediate transfer member, the release agent is removed by polishing the surface of the intermediate transfer member. This prevents the occurrence of the filming phenomenon.

FIG. 6 is an explanatory diagram showing an outline of the configuration of an example of a color image forming apparatus according to the second embodiment of the present invention.
This color image forming apparatus is a position downstream of the cleaning area by the intermediate transfer body cleaning device 27 in the moving direction of the intermediate transfer belt 20 instead of providing the recording material cooling means in the color image forming apparatus shown in FIG. In addition, the basic configuration is the same as that of the color image forming apparatus shown in FIG. 1 except that a polishing means 70 for polishing the surface of the intermediate transfer belt 20 is provided. In FIG. 6, the same components as those in the color image forming apparatus shown in FIG.

  As shown in FIG. 7, the polishing means 70 includes a long polishing sheet member 71, and is driven from an original winding part 72 having a rotatable original winding shaft 72 </ b> A around which the polishing sheet member 71 is wound. On the path to the winding portion 73 having the winding shaft 73A rotated in the clockwise direction (indicated by an arrow in the figure) by the source, the pressure roller 74 is pressed against the intermediate transfer belt 20 by being pressed by the pressing roller 74. Region G is formed. In this polishing means 70, the polishing sheet member 71 is configured to move in the polishing region G in the direction opposite to the moving direction of the intermediate transfer belt 20, for example.

  As the polishing sheet member 71, for example, a member obtained by uniformly bonding an abrasive made of alumina particles on a sheet base made of resin is used.

The pressing roller 74 is provided so that its rotation shaft 74A can be moved in a direction in which it comes in contact with and separates from the surface of the intermediate transfer belt 20 by an appropriate driving means (not shown) such as a cam mechanism. When the belt 20 is polished, the belt 20 is moved in a direction approaching the intermediate transfer belt 20, whereby the polishing sheet member 71 is pressed against the surface of the intermediate transfer belt 20.
It is preferable that the polishing sheet member 71 is in pressure contact with the intermediate transfer belt 20 with a load of 4.9 to 49 N, for example. Thereby, a sufficient polishing effect (adherent removal effect) can be obtained without excessively polishing the surface of the intermediate transfer belt 20, and the original performance of the intermediate transfer belt 20 can be maintained over a long period of time.

  The circumferential length of the intermediate transfer belt 20 in the polishing region G is preferably 2 mm or more, for example. If this length is too small, a sufficient polishing effect cannot be obtained, and it becomes difficult to maintain the original performance of the intermediate transfer belt 20.

  The operation state of the polishing unit 70 is controlled based on an output value relating to the surface temperature of the fixed image carrying recording material S detected by the temperature detection unit 45. Specifically, when an image is formed on the other surface of the fixed image carrying recording material S, the surface temperature of the fixed image carrying recording material S is higher than the temperature t1 related to the DSC curve of the release agent, more preferably the temperature. When it is higher than t2 (<t1), the polishing sheet member 71 is brought into pressure contact with the intermediate transfer belt 20 with an appropriate amount of pressure contact force. Further, the pressure contact force of the polishing sheet member 71 with respect to the intermediate transfer belt 20 may be adjusted according to the surface temperature detected by the temperature detecting means 45.

According to the color image forming apparatus having the above configuration, it is possible to reliably prevent the offset phenomenon from occurring without using a release agent such as silicone oil for the heating roller 31 in the fixing device 30.
In addition, when forming images on both sides of the recording material P, the fixed image C on the fixed image carrying recording material S during the period from the fixing nip region N to the secondary transfer region T2 of the fixed image carrying recording material S. The release agent relating to the toner constituting the toner is introduced into the secondary transfer region T2 in a state where the release agent cannot be sufficiently solidified. As a result, the release agent adheres to the surface of the intermediate transfer belt 20. Even in this case, the original performance of the intermediate transfer belt 20 can be maintained by polishing the surface of the intermediate transfer belt 20 by the polishing means 70, and the temperature of the fixed image carrying recording material S can be detected, By operating the polishing means 70 under operating conditions adjusted based on the detection result, the intermediate transfer belt 20 is not excessively polished, and the service life of the intermediate transfer belt 20 is greatly increased. The required polishing effect can be obtained without lowering the film, and therefore, a filming phenomenon caused by a release agent does not occur, and a high-quality image can be stably formed over a long period of time. Can do.

In the above, a fixing device having no release agent supply means is used, and a toner having a release agent contained therein is used to improve the release property and fixability. Although the image forming apparatus has been described, color image formation having a configuration in which the release property and the fixability are improved by using a toner containing no release agent and using a fixing device having a release agent supply means The present invention can be applied to an apparatus.
Specifically, in such a color image forming apparatus, in the color image forming apparatus shown in FIG. 6, a release agent is used as a fixing unit on one fixing rotating body on which an unfixed toner image on a recording material is formed. The image forming apparatus has the same configuration as that of the image forming apparatus shown in FIG. 6 except that a fixing device provided with a release agent supplying means that is applied and supplied is used.
As the fixing device, for example, the one having the configuration shown in FIG. 5 can be used.

In such an image forming apparatus, the same operations and effects as those of the image forming apparatus having the configuration shown in FIG. 6 can be obtained. That is, a fixing device having a release agent supply unit is used, and the release agent is supplied to one fixing rotator in contact with the secondary transfer toner image by the release agent supply unit. Therefore, it is possible to reliably prevent the occurrence of an offset phenomenon.
Moreover, when images are formed on both sides of the recording material P, the fixed image carrying recording material S adheres to the surface of the fixed image carrying recording material S from the fixing nip region N to the secondary transfer region T2. Even if the release agent is introduced into the secondary transfer region T2 in a state where the release agent cannot be sufficiently solidified, the release agent adheres to the surface of the intermediate transfer belt 20. By polishing the surface of the intermediate transfer belt 20 by the polishing means 70, the original performance of the intermediate transfer belt 20 can be maintained, and the temperature of the fixed image carrying recording material S is detected and based on the detection result. By operating the polishing means 70 under the adjusted operating conditions, the intermediate transfer belt 20 is not excessively polished, and the service life of the intermediate transfer belt 20 is not significantly reduced. It is possible to obtain a polishing effect of essential, therefore, release agent without problems such as filming occurs due, it is possible to stably form over a long period of time with high quality image.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, the recording agent cooling unit and the polishing unit can be configured to be operated under an operation condition corresponding to a fixing process condition such as a fixing temperature and a process speed. In other words, when multiple types of image forming modes set to different fixing process conditions and process speeds are set, the surface temperature of the fixed image-carrying recording agent is not actually detected, but according to the image forming mode. Thus, the release agent or the recording material relating to the toner constituting the fixed image formed on one surface between the fixing nip region and the secondary transfer region, in which the operating states of the recording agent cooling unit and the polishing unit are controlled. When an image forming mode is set in which it is difficult to sufficiently solidify the release agent attached to the surface of the recording material, the recording material cooling unit or the polishing unit is activated.

  The recording material cooling means in the image forming apparatus according to the first embodiment is configured to cool the fixed image carrying recording material by supplying cooling air directly to the other surface of the fixed image carrying recording material. It may be.

  The fixing device provided with the release agent supply means used in the first embodiment and the second embodiment is not limited to the one having the above-described configuration, and may be, for example, the configuration shown in FIGS.

  The fixing device 30B shown in FIG. 8 will be described in detail. The fixing device 30B includes a heating roller 31 that is one fixing rotating member in contact with one surface of the recording material P on which an unfixed toner image is formed, A pressure rotator 80, which is the other fixing rotator, is provided so as to form a fixing nip region N1 by being pressed against the heating roller 31. The fixing nip region N1 in the rotation direction of the heating roller 31 is provided. A release agent supply means 60 for applying and supplying a release agent to the surface of the heating roller 31 is provided at a further upstream position. In FIG. 8, the same components as those of the fixing device shown in FIG.

The pressure rotator 80 includes an endless fixing belt 81 that travels while being in contact with the surface of the heating roller 31, and the fixing belt 81 is pressed against the heating roller 31 via the fixing belt 81. A fixing nip forming roller 82 provided in a heated state, a roller-shaped external heating rotating body 86 having a heating source 86A such as a halogen heater lamp disposed therein, and a tension of an appropriate magnitude for the fixing belt 81. Is supported by a support roller 87 that imparts heat, and is pressed against the heating roller 31 by a pressing pad 88, thereby forming a fixing nip region N1.
The heating roller 31 and the external heating rotator 61 have the same configuration as that in the fixing device shown in FIG.

The fixing nip forming roller 82 constituting the pressure rotator 80 includes, for example, a cylindrical metal core 83 made of metal, an elastic layer 84 formed on the outer peripheral surface of the metal core 83, and an elastic layer 84. The cover layer 85 is formed on the outer peripheral surface and presses the heating roller 31 via the fixing belt 81.
As the material constituting the metal core 83, the material constituting the elastic layer 84, and the material constituting the coating layer 85, those exemplified as the material constituting the heating roller 31 in the fixing device shown in FIG. it can.
The thickness of the elastic layer 84 is smaller than the thickness of the elastic layer 33 in the heating roller 31, for example, 0.1 to 2 mm.
Further, the fixing nip forming roller 82 preferably has a hardness equal to or higher than the hardness of the heating roller 31, for example, Asker C hardness of 80 ° or higher.

As the fixing belt 81, a belt in which a coating layer is formed on the surface of an endless belt base via an elastic layer can be suitably used.
As a material constituting the belt base material, a metal material such as nickel or stainless steel, or a resin material such as polyimide can be used. Moreover, the thickness of a belt base material is 40-60 micrometers, for example, when forming with a metal material, and is 50-90 micrometers when comprised with a resin material, for example.
As a material constituting the elastic layer, for example, silicone rubber can be used. Moreover, the thickness of an elastic layer is 150-250 micrometers, for example.
Examples of the material constituting the coating layer include fluorine resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), and a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP). Can be used. Moreover, the thickness of a coating layer is 20-50 micrometers, for example.

Further, the fixing device shown in FIG. 9 will be specifically described. The fixing device 30C includes a heating rotator 90 which is one fixing rotator in contact with one surface of the recording material P on which the toner image is formed. And a pressure roller 36 that is the other fixing rotator provided so as to be pressed against the heating rotator 90 to form the fixing nip region N2. In FIG. 8, the same components as those of the fixing device shown in FIG.
The heating rotator 90 includes an endless fixing belt 91 that travels while being in contact with the surface of the pressure roller 36, and the fixing belt 91 is pressed against the pressure roller 36 via the fixing belt 91. The fixing nip forming roller 92 provided in this state and a heating roller 96A such as a halogen heater lamp are suspended and supported by a supporting roller 96 disposed therein. A fixing nip region N2 that is convex with respect to the surface is formed.
The heating rotator 96 is formed by forming a coating layer 98 made of, for example, a fluororesin on the surface of a cylindrical cored bar 97 made of metal.
The pressure roller 36 and the external heating rotator 61 have the same configuration as that of the fixing device shown in FIG.

The fixing nip forming roller 92 constituting the heating rotator 90 includes a cylindrical cored bar 93 made of, for example, metal, and an elastic layer 94 formed on the outer peripheral surface of the cored bar 93. The thickness of the elastic layer 94 is larger than the thickness of the elastic layer 38 of the pressure roller 36, for example, 3 to 8 mm, and the hardness of the fixing nip forming roller 92 is equal to or lower than the hardness of the pressure roller 36. It is preferable that there is an Asker C hardness of 35 to 70 °. The elastic layer 94 is preferably made of a material having low thermal conductivity. Examples of such a material include silicone sponge rubber.
The fixing nip forming roller 92 is pressed by the pressure roller 36 through the fixing belt 91 with a pressing force of 1.7 N / cm, for example.

As the fixing belt 91, a belt in which a coating layer is formed on the surface of an endless belt base via an elastic layer can be suitably used.
The thickness of the belt base material is, for example, 40 to 60 μm when formed of a metal material, and the thickness of the elastic layer is, for example, 150 to 250 μm, for example, when formed of a resin material. The thickness of the layer is, for example, 20 to 50 μm.

  In the above, as the materials constituting the fixing nip forming roller 92 and the fixing belt 91 constituting the heating rotator 90, those exemplified as those constituting the fixing device shown in FIG. 8 can be used.

In the fixing device 30 </ b> C, a release agent supply unit 60 that applies and supplies a release agent to the surface of the heating rotator 90 is provided so as to contact and press the support roller 96 through the fixing belt 91. ing.
The release agent supply means 60 has the same configuration as that used in the fixing device shown in FIG.

  In the present invention, the polishing means is not limited to the above configuration, for example, a fur brush in which a brush member having sufficiently high hardness and rigidity is implanted on the outer peripheral surface of the core member, For example, it may be constituted by a polishing roller having an abrasive layer formed on the outer peripheral surface of a roller base made of metal or rubber.

1 is an explanatory diagram showing an outline of a configuration in an example of a color image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory cross-sectional view illustrating an outline of a configuration of an example of a fixing device in the color image forming apparatus illustrated in FIG. 1. It is explanatory drawing which shows the outline of a structure in an example of a recording material cooling means. It is explanatory drawing which shows typically the DSC curve of the mold release agent used in this invention. FIG. 6 is a cross-sectional view illustrating the outline of the configuration of another example of the fixing device in the color image forming apparatus of the present invention. It is explanatory drawing which shows the outline of a structure in an example of the color image forming apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the outline of a structure in an example of a grinding | polishing means. FIG. 10 is a cross-sectional view for explaining the outline of the configuration of still another example of the fixing device in the color image forming apparatus of the present invention. FIG. 10 is a cross-sectional view for explaining the outline of the configuration of still another example of the fixing device in the color image forming apparatus of the present invention.

Explanation of symbols

10Y, 10M, 10C, 10K Toner image forming unit 11 Photoconductor 12 Charging means 13 Exposure means 14 Development means 141 Development sleeve 15 Primary transfer means 15A Primary transfer roller 16 Photoconductor cleaning device 18 Recording material supply unit 20 Intermediate transfer belt 21A, 21B, 21C, 21D Support roller 25 Secondary transfer means 25A Secondary transfer roller 26 Intermediate transfer member cleaning blade 27 Intermediate transfer member cleaning device T1 Primary transfer region T2 Secondary transfer region P Recording material 30 Fixing device 30A Fixing device 31 Heating roller 36 Pressure roller 32, 37 Core metal 33, 38 Elastic layer 34, 39 Release layer 35A, 35B Heat source N Fixing nip area 40 Reverse conveying mechanism 41 Reverse conveying path S Fixed image carrying recording material C Fixed image 45 Temperature detecting means 50 Recording material cooling means DESCRIPTION OF SYMBOLS 1 Cooling cylindrical member 52 Thermal conduction member 53 Cooling air supply means 54A, 54B Roller member 55 Belt-like member R Fixed image carrying recording material passage area L Cooling area 60 Release agent supply means 61 External heating rotator 62 Core metal 63 Coating layer 64 Heat source 65 Web 66A Original winding shaft 66 Original winding portion 67A Winding shaft 67 Winding portion W Release agent application area 70 Polishing means 71 Polishing sheet member 72 Original winding portion 72A Original winding shaft 73 Winding portion 73A Winding shaft 74 Pressing roller 74A Rotating shaft G Polishing area 30B Fixing device N1 Fixing nip area 80 Pressure rotator 81 Fixing belt 82 Fixing nip forming roller 83 Core metal 84 Elastic layer 85 Covering layer 86 External heating rotator 86A Heating source 87 Support roller 88 Press pad 30C Fixing device 90 Heating rotating body 91 Fixing base DOO 92 fixing nip forming roller 93 metal core 94 elastic layer 96 supporting rollers 96A heating source 97 core metal 98 covering layer N2 fixing nip area

Claims (5)

The toner image formed on the rotated image forming body is primary transferred by a primary transfer unit on an intermediate transfer body which is provided with a cleaning member in contact with the surface and moves while contacting the image forming body. To form a primary transfer toner image, and the primary transfer toner image is pressed against the surface of the intermediate transfer member to form a secondary transfer region, and the secondary transfer unit is provided to perform secondary transfer on the recording material. By performing an image forming operation of forming a secondary transfer toner image on the recording material and thermally fixing the secondary transfer toner image formed on the recording material by a fixing unit, An image form that forms an image and forms an image on the other surface of the recording material by performing the image forming operation by reversing and conveying the recording material on which the image is formed on the one surface and introducing the recording material into the secondary transfer region. In the image forming apparatus mode is set,
As the toner, a toner containing a release agent is used,
The fixing means is arranged such that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material It does not have a release agent supply means to apply and supply a release agent to
A temperature detection means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip area to the secondary transfer area, and a position downstream of the temperature detection means in the recording material conveyance direction. In addition, an image forming apparatus is provided with a recording material cooling unit that is operated under an operation condition according to a detection result by the temperature detection unit. The toner image formed on the rotated image forming body is primary transferred by a primary transfer unit on an intermediate transfer body which is provided with a cleaning member in contact with the surface and moves while contacting the image forming body. To form a primary transfer toner image, and the primary transfer toner image is pressed against the surface of the intermediate transfer member to form a secondary transfer region, and the secondary transfer unit is provided to perform secondary transfer on the recording material. By performing an image forming operation of forming a secondary transfer toner image on the recording material and thermally fixing the secondary transfer toner image formed on the recording material by a fixing unit, An image form that forms an image and forms an image on the other surface of the recording material by performing the image forming operation by reversing and conveying the recording material on which the image is formed on the one surface and introducing the recording material into the secondary transfer region. In the image forming apparatus mode is set,
As the toner, a toner containing a release agent is used,
The fixing means is arranged such that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material It does not have a release agent supply means to apply and supply a release agent to
A temperature detecting means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip region to the secondary transfer region, and is downstream of the cleaning member contact position in the moving direction of the intermediate transfer member. An image forming apparatus, characterized in that a polishing means for polishing the surface of the intermediate transfer member, which is operated at an operating condition according to a detection result by the temperature detection means, is provided at a position on the side. The toner image formed on the rotated image forming body is primary transferred by a primary transfer unit on an intermediate transfer body which is provided with a cleaning member in contact with the surface and moves while contacting the image forming body. To form a primary transfer toner image, and the primary transfer toner image is pressed against the surface of the intermediate transfer member to form a secondary transfer region, and the secondary transfer unit is provided to perform secondary transfer on the recording material. By performing an image forming operation of forming a secondary transfer toner image on the recording material and thermally fixing the secondary transfer toner image formed on the recording material by a fixing unit, An image form that forms an image and forms an image on the other surface of the recording material by performing the image forming operation by reversing and conveying the recording material on which the image is formed on the one surface and introducing the recording material into the secondary transfer region. In the image forming apparatus mode is set,
As the toner, a toner containing a release agent is used,
The fixing means is arranged such that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material It does not have a release agent supply means to apply and supply a release agent to
The recording material cooling means is provided in the recording material reversal conveyance path from the fixing nip area to the secondary transfer area, and the recording material cooling means is operated under an operating condition corresponding to the fixing condition and the process speed. Image forming apparatus. The toner image formed on the rotated image forming body is primary transferred by a primary transfer unit on an intermediate transfer body which is provided with a cleaning member in contact with the surface and moves while contacting the image forming body. To form a primary transfer toner image, and the primary transfer toner image is pressed against the surface of the intermediate transfer member to form a secondary transfer region, and the secondary transfer unit is provided to perform secondary transfer on the recording material. By performing an image forming operation of forming a secondary transfer toner image on the recording material and thermally fixing the secondary transfer toner image formed on the recording material by a fixing unit, An image form that forms an image and forms an image on the other surface of the recording material by performing the image forming operation by reversing and conveying the recording material on which the image is formed on the one surface and introducing the recording material into the secondary transfer region. In the image forming apparatus mode is set,
The fixing unit is arranged so that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material A release agent supply means for applying and supplying the release agent to
A temperature detection means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip area to the secondary transfer area, and a position downstream of the temperature detection means in the recording material conveyance direction. In addition, an image forming apparatus is provided with a recording material cooling unit that is operated under an operation condition according to a detection result by the temperature detection unit. The toner image formed on the rotated image forming body is primary transferred by a primary transfer unit on an intermediate transfer body which is provided with a cleaning member in contact with the surface and moves while contacting the image forming body. To form a primary transfer toner image, and the primary transfer toner image is pressed against the surface of the intermediate transfer member to form a secondary transfer region, and the secondary transfer unit is provided to perform secondary transfer on the recording material. By performing an image forming operation of forming a secondary transfer toner image on the recording material and thermally fixing the secondary transfer toner image formed on the recording material by a fixing unit, An image form that forms an image and forms an image on the other surface of the recording material by performing the image forming operation by reversing and conveying the recording material on which the image is formed on the one surface and introducing the recording material into the secondary transfer region. In the image forming apparatus mode is set,
The fixing unit is arranged so that two fixing rotators are pressed against each other to form a fixing nip region, and the surface of one fixing rotator that is in contact with the secondary transfer toner image on the recording material A release agent supply means for applying and supplying the release agent to
A temperature detecting means for detecting the surface temperature of the recording material is provided in the recording material reverse conveyance path from the fixing nip region to the secondary transfer region, and is downstream of the cleaning member contact position in the moving direction of the intermediate transfer member. An image forming apparatus, characterized in that a polishing means for polishing the surface of the intermediate transfer member, which is operated at an operating condition according to a detection result by the temperature detection means, is provided at a position on the side.