JPH0619352A - Image forming device - Google Patents

Abstract

PURPOSE:To realize an image forming device capable of always stably obtaining an excellent image by preventing releasing agent from transferring and adhering to respective devices at the time of resupplying paper. CONSTITUTION:In the image forming device 1 which is provided with a fixing device 18 for fixing the image by applying the releasing agent to a fixing roller (rotating body for fixing) and consecutively performs image forming actions that the image is fixed by the device 18 plural times, a means (transfer material detecting sensor S or detector D, etc.) for inhibiting the second and succeeding image forming actions to a resin transfer material is provided. Since the second and succeeding image forming actions to the resin transfer material which has no water absorption ability and no oil absorption ability as a transfer material are inhibited, the releasing agent is prevented from transferring and adhering to the respective devices at the time of resupplying the resin transfer material, and the excellent image is always stably obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic apparatus which forms an image.

[0002]

2. Description of the Related Art As an example of a conventional image forming apparatus, there is a color electrophotographic apparatus which forms a color image as shown in FIG.

The color electrophotographic apparatus shown in FIG. 15 includes a transfer material conveying system I provided from the right side of the apparatus main body 1 (right side of FIG. 15) to a substantially central portion of the apparatus main body 1, and the apparatus main body 1 in general. A latent image forming portion II provided in the central portion in the vicinity of the transfer drum 15 constituting the transfer material conveying system I, and a rotary developing device III arranged in the vicinity of the latent image forming portion II. It is configured to include.

By the way, the transfer material carrying system I is constructed as follows.

That is, an opening is formed in the right wall of the apparatus main body 1, and removable transfer material supply trays 2 and 3 are arranged so as to partially project outside the machine. . Paper feed rollers 4 and 5 are arranged substantially directly above the trays 2 and 3, respectively, and the transfer drums 4 and 5 and the transfer drum arranged on the left side and rotating in the direction of arrow a. The paper feed roller 6 and the paper feed guides 7 and 8 are provided so as to be connected to the paper 15.

A contact roller 9, a gripper 10, a transfer material separating charger 11, and a separating claw 12 are sequentially arranged near the outer peripheral surface of the transfer drum 15 from the upstream side to the downstream side in the rotational direction. . Further, a transfer charger 13 and a transfer material separating charger 14 are disposed on the inner peripheral side of the transfer drum 15. Then, as shown in FIG. 16, a transfer sheet 92 made of polyvinylidene fluoride or the like is attached to a portion of the transfer drum 15 around which the transfer material is wound. Be closely attached.

Further, a conveyor belt means 16 is provided on the upper right side of the transfer drum 15 adjacent to the separation claw 12, and a fixing device 18 is provided at the end (right) end of the conveyor belt means 16 in the transfer material conveying direction. It is arranged. Further, in the downstream of the fixing device 18 in the transfer material conveying direction, the device main body 1
A paper discharge tray 17 that is detachable with respect to is disposed.

Next, the structure of the latent image forming section II will be described.

In FIG. 15, reference numeral 19 denotes a photosensitive drum, which is an image bearing member that rotates in the direction of arrow b, and is arranged with its outer peripheral surface in contact with the outer peripheral surface of the transfer drum 15. Further, above the photosensitive drum 19, a charge removing charger 20, a cleaning device 21, and a primary charger 23 are sequentially arranged from the upstream side to the downstream side in the rotation direction of the photosensitive drum 19. Also, above the photosensitive drum 19,
An image exposure means 24 such as a laser beam scanner for forming an electrostatic latent image on the photosensitive drum 19 and an image exposure reflection means 25 such as a mirror are provided.

Finally, the structure of the rotary developing device III will be described.

That is, a rotating body 26 is rotatably arranged at a position facing the outer peripheral surface of the photosensitive drum 19, and four kinds of developing devices 27Y, 27M, 2 are provided in the rotating body 26.
7C and 27BK are mounted at four positions in the circumferential direction, and the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 19 is developed and visualized by these developing devices 27Y, 27M, 27C and 27BK. Has become. 27Y is a yellow developing device, 27M is a magenta developing device, and 27C.
Is a cyan developing device, and 27BK is a black developing device.

The sequence of the color electrophotographic apparatus configured as described above will first be briefly described by taking the case of the full color mode as an example.

That is, when the photosensitive drum 19 rotates in the direction of arrow b in FIG. 15, the photosensitive member on the photosensitive drum 19 is uniformly charged by the primary charger 23. At this time, the operating speed of each part (hereinafter referred to as process speed) is 1
It is set to 60 mm / sec.

When the photosensitive member of the photosensitive drum 19 is uniformly charged by the primary charger 23 as described above, image exposure is performed by the laser light E modulated by the yellow image signal of the original 28, and the photosensitive drum 19 is exposed. An electrostatic latent image is formed on the electrostatic latent image, and the electrostatic latent image is developed by the yellow developing device 27Y which is previously set at the developing position by the rotation of the rotating body 26.

On the other hand, the transfer material conveyed through the paper feed guide 7, the paper feed roller 6 and the paper feed guide 8 is held by the gripper 10 at a predetermined timing, and the contact roller 9 and the corresponding contact roller are held. It is wound around the transfer drum 15 electrostatically by the electrode facing 9. At this time, the transfer drum 15 is synchronized with the photosensitive drum 19 as shown in FIG.
Yellow developing device 27Y
The developed image developed in 1 is transferred by the transfer charger 13 at a portion where the outer peripheral surface of the photosensitive drum 19 and the outer peripheral surface of the transfer drum 15 are in contact with each other. Then, the transfer drum 15 continues to rotate and prepares for transfer of the next color (magenta in FIG. 15).

On the other hand, the photosensitive drum 19 is de-charged by the de-charging charger 20, cleaned by a cleaning means 21 by a conventionally known blade method, and then re-charged by the primary charger 23, according to the next magenta image signal. It receives the image exposure as described above. Then, in the rotary developing device III, the rotating body 26 rotates while the electrostatic latent image based on the magenta image signal is formed on the photosensitive drum 19 by the image exposure, and the magenta developing device 27M moves to a predetermined developing position. It is fixed and a predetermined magenta development is performed.

Subsequently, the same process as described above is carried out for cyan color and black color respectively, and when the transfer of four colors is completed, the four-color visible image formed on the transfer material is charged by each charger 20. , 14 to eliminate static electricity, and gripper 1
When the holding of the transfer material by 0 is released, the transfer material is separated from the transfer drum 15 by the separating claw 12, and is sent to the fixing device 18 by the conveyor belt means 16 to fix the fixing device 1.
At 8, the visible image is fixed by heat and pressure, thus completing the series of full-color print sequences and forming the desired full-color print image. The fixing operation of the fixing device 18 is performed at the process speed of 160 mm.
It is performed at 90 mm / sec, which is slower than / sec. This is because a sufficient heating amount must be given to the toner when the unfixed image in which two to four layers of toner are stacked is melt-mixed as described later, and the fixing is performed at a speed slower than the process speed. The amount of heat applied to the toner is increased by performing.

As described above, since the color image has two to four layers of multicolor toner, the color image electrophotographic apparatus is different from the monochrome apparatus in the following two points. have.

That is, the first feature relates to the toner to be used, and since the toner is required to have good melting property and color mixing property when heat is applied, it has a low softening point. Further, a sharp melt toner having a low melt viscosity (referred to as a sharp melt toner) is used. By using such a sharp melt toner, the color reproduction range of the copy can be expanded and a color copy faithful to the multicolor or full-color image of the original can be obtained.

By the way, in the sharp melt toner, for example, a binder resin such as a polyester resin or a styrene-acrylic ester resin, a colorant (a dye or a sublimable dye), a toner forming material such as a charge control agent is melt-kneaded and pulverized. , Manufactured by classifying. If necessary, various external additives (for example, hydrophobic colloidal silica) are added to the toner.
You may add the external addition process of adding.

As such a color toner, it is particularly preferable to use a polyester resin as the binder resin in consideration of fixing property, sharp melt property and the like. As the sharp melt polyester resin, a polymer compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid is exemplified.

In particular, the following equation

[0023]

[Chemical 1] (In the above formula, R is an ethylene or propylene group, x,
y is a positive integer of 1 or more, and the average value of x + y is 2 to 10), and a bisphenol derivative represented by or a substituted product thereof is used as a diol component, and a divalent or higher carboxylic acid or an acid anhydride thereof is used. Or a carboxylic acid component consisting of a lower alkyl ester thereof (eg, fumaric acid,
A polyester resin obtained by at least copolycondensing maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable because it has sharp melting characteristics.

Therefore, the softening point of the polyester resin is 7
5 to 150 ° C, preferably 80 to 120 ° C is suitable.

Here, an example of softening characteristics of a sharp melt toner containing a polyester resin as a binder resin is shown in FIG.
7 shows.

The softening properties were obtained by the following measurements. That is, a flow tester CFT-500A type (manufactured by Shimadzu Corp.) was used, a die (nozzle) diameter of 0.2 mm and a thickness of 1.0 mm was applied with an extrusion load of 20 kg, and preheating was performed at an initial setting temperature of 70 ° C. for 300 seconds. After that, a plunger depression amount-temperature curve (hereinafter referred to as a softening S-shaped curve) of the toner drawn when the temperature was increased at a constant rate of 6 ° C./min was obtained.
As a sample toner, fine powder precisely weighed from 1 to 3 g is used, and the cross-sectional area of the plunger is 1.0 cm ² .

Thus, the softened S-shaped curve becomes a curve as shown in FIG. That is, as the temperature rises at a constant speed, the toner is gradually heated and starts to flow (plunger descending A → B). Then, when the temperature is further increased, the toner in the melted state largely flows out (B → C → D), and the plunger lowering is stopped and ended (D → E). The height H of the S-shaped curve indicates the total outflow amount, and the temperature T0 corresponding to the point C of the height H / 2 indicates the softening point of the toner.

By the way, whether or not the toner and the binder resin have a sharp melt property can be determined by measuring the apparent melt viscosity of the toner or the binder resin.

With regard to the toner or binder resin having a sharp melt property, the temperature when the apparent melt viscosity is 10 ³ poise is T1, and the temperature when the apparent melt viscosity is 5 × 10 ² poise is T2. When the following formula:

[0030]

## EQU1 ## T1 = 90 to 150.degree. C. | .DELTA.T | = | T1-T2 | = 5 to 20.degree.

The sharp-melting resin having such temperature-melt viscosity characteristics is characterized in that the viscosity is extremely sharply lowered by heating. Such a decrease in viscosity causes a proper mixing of the uppermost toner layer and the lowermost toner layer, and further, the transparency of the toner layer itself is sharply increased, and good color-reducing mixing is caused.

However, such a sharp-melting color toner has a large affinity and has a property of being easily offset to the fixing roller. Therefore, in the fixing device of the image forming apparatus using the color toner as described above, it is necessary to exhibit high releasability for a long period of time.

The fixing device 18, which is the second feature of the color electrophotographic apparatus, will be described below with reference to FIG.

In the fixing device 18 shown in FIG. 18, 29
Is a fixing roller as a fixing means, which has an HTV (high temperature vulcanization type) silicone rubber 32 on an aluminum cored bar 31 and an addition type LTV (low temperature vulcanization type) silicone rubber 33 on the outside thereof. The thickness is 3 mm and the diameter is 40 mm. The addition type LTV silicone rubber 3
3, a straight-chain dimethylpolysiloxane endblocked viscosity 10 ⁴ poise (40 parts by weight) is composed out with resin-like organopolysiloxane is Rutter polymer (60 parts by weight).

On the other hand, the pressure roller 30, which is a pressure means, has an HTV with a thickness of 1 mm on a core metal 34 made of aluminum.
Further, on the surface thereof, the same LTV as the surface layer material of the fixing roller 29 is used.
The silicone rubber layer 35 is formed to have a diameter of 40 mm.

By the way, the fixing roller 29 is provided with a halogen heater 36 as a heat generating means, and the pressure roller 3 is provided.
Similarly, a heater 37 is disposed in the core metal 34 at 0, and heating is performed from both sides. Then, the temperature of the pressure roller 30 is detected by the thermistor 38 in contact with the pressure roller 30, and the halogen heaters 36 and 37 are controlled by the control device 39 based on the detected temperature to press the fixing roller 29 and the pressure roller 30. Both the temperatures of the rollers 30 are maintained at a constant value of about 170 ° C. The fixing roller 29 and the pressure roller 30 are pressed at a total pressure of about 40 kg by a pressure mechanism (not shown).

Further, in FIG. 18, O is an oil applying device which is a releasing agent applying means, C is a cleaning device, and C1 is a cleaning blade which removes oil and dirt on the pressure roller 30.

The oil applying device O includes an oil pan 52.
Dimethyl silicone oil 53 in a (K manufactured by Shin-Etsu Chemical Co., Ltd.
F96-300 cs) through the oil pumping roller 54 and the oil applying roller 55, and the oil application amount adjusting blade 4
The amount of oil applied is regulated by 5 and applied on the fixing roller 29. In the example shown in FIG. 18, the coating amount is 0.08 g / A4 by the measuring method described later.

By the way, the coating amount of the silicone oil 53 by the oil coating device O is obtained as follows.

That is, first, the weight of 50 A4 size blank sheets is set to A1 (g), and the image is not transferred onto this blank sheet.
Silicone oil 53 for the rubber layer 33 of the fixing roller 29
Also, the weight of 50 blank sheets after passing between the fixing roller 29 and the pressure roller 30 without applying the above is set to B (g). Next, similarly, the weight of another 50 sheets of A4 size paper is set to A2 (g) and the image is not transferred onto this white paper, but the silicone oil 53 is applied to the rubber layer 33 of the fixing roller 29. Fixing roller 29 and pressure roller 3
C (g) is the weight of 50 blank sheets after passing between 0 and 0.

Using the above weights A1, B, A2 and C,
The application amount X (g) of the silicone oil 41 per one A4 size blank sheet is obtained by the following equation.

[0042]

## EQU2 ## X = (C + A1-B-A2) / 50 On the other hand, in the cleaning device C, the non-woven fabric web 57a made of Nomex (product name) is pressed against the fixing roller 29 by the pressing roller 57, so that the fixing roller 29 moves. A device for cleaning the surface. The web 57a is appropriately wound by a winding device (not shown) so that toner or the like does not accumulate on the contact portion of the web 57a with the fixing roller 29.

By the way, the color electrophotographic apparatus described above forms a visible image only on one surface of the transfer material, but there is also an apparatus capable of forming this visible image on both the front surface and the back surface of the transfer material. Already proposed. This device will be described below with reference to FIG.

The apparatus shown in FIG. 19 is a color electrophotographic apparatus similar to that shown in FIG. 15, except that an image can be formed on both sides of the transfer material. The mechanism for double-sided image formation will be described below. The same elements as those shown in FIG. 15 are designated by the same reference numerals, and the description thereof will be omitted.

This apparatus is provided with a re-feeding roller 40 and a conveyance path 41 which constitute a conveyance mechanism for double-sided image formation. The sheet re-feeding roller 40 is provided below the sheet ejection roller 42 with the transfer material once placed on the sheet ejection tray 17 in the latent image forming section.
The transfer material is sent to the latent image forming section II via the conveying path 41.

Next, a double-sided copy operation of a color image by the color electrophotographic apparatus will be described.

The transfer material, which has been developed in the rotary developing device III and has an unfixed toner image on its surface, is transported by the transport belt means 16 and fixed by the fixing roller 29 and the pressure roller 30, and then the paper discharge roller. It is placed on the paper discharge tray 17 by 42. After this, the output tray 17
The upper transfer material is re-fed by the re-feed roller 40, passes through the conveyance path 41, and is conveyed again to the latent image forming unit II, and a color image is formed on the back surface in the same manner as the front surface. Thus, the transfer material having the color image already fixed on the front surface and carrying the unfixed color toner image transferred on the back surface is sent to the fixing device 18 by the conveyor belt means 16 and carried on the back surface here. Unfixed color toner image is fixed,
Finally, the paper is discharged to the paper discharge tray 17, and a series of double-sided color copying operations are completed here.

Further, in the electrophotographic apparatus, a visible image is formed on the surface of the transfer material twice or more and then fixed (that is, fixed).
Image forming operation is performed several times in succession),
This will be described with reference to FIG.

That is, in FIG. 19, DP is a transport switching plate for performing a multiple image forming operation, and the transport switching plate DP is at the position DP1 shown in the figure during normal single-sided image formation or double-sided image formation. , At the position of DP2 shown in the figure when multiple images are formed. When forming multiple images, 1
The transfer material having the toner image fixed on the surface (surface) is conveyed to the latent image forming portion II by the re-feeding roller 40 through the conveying passage 41, and thereafter, the same operation is performed on the same surface. Is repeated.

[0050]

However, when the above-described double-sided color copy or multiple image formation is performed, the following problems occur.

That is, when the first image forming operation is completed and the first heat fixing is performed, the oil as the release agent is attached on the toner and the transfer material, and the transfer material on which the oil is attached is double-sided copied. Alternatively, when the paper is re-fed for forming a multiple image, the toner surface on which the first fixing is performed faces the transfer drum side, and the transfer material winds around the transfer drum and adheres to the toner or paper. Oil is transferred to the transfer sheet on the transfer drum. Then, the oil transferred to the transfer sheet is transferred to the photosensitive drum by the rotation of the transfer drum after the transfer material is separated from the transfer drum.

When the oil is transferred to the photosensitive drum as described above, the toner on the photosensitive drum cannot be cleaned by the cleaning device, or the oil is not applied to a portion of the photosensitive drum other than the predetermined latent image forming portion. There is a problem in that toner adheres to the upper part of the image, and in the subsequent copying, a dirty image with excessive toner adhered is formed.

Further, there is a problem in that the paper feed roller and the paper feed guide in the paper transport path are soiled with oil, which causes oil stains on the paper and paper feed slips during the next copy.

In particular, when a resin-like transfer material having no water-absorbing property or oil-absorbing property is used as the transfer material, the oil as a releasing agent at the time of fixing remains on the surface of the resin-like transfer material as it is, and the amount of oil applied is regulated to be small. Even so, the above problem becomes more remarkable as compared with the case of using another transfer material. Here, the resinous transfer material is specifically a transparency sheet for overhead projector (hereinafter referred to as an OHP sheet), a sealing sheet, an air print sheet, etc. It refers to a material having a two-layer structure of a transfer material or paper and a resinous film or a multilayer structure of more than that.

Therefore, the object of the first to third inventions is to prevent transfer of the release agent to each device when re-feeding the transfer material, and always obtain a stable and good image. It is to provide an image forming apparatus capable of

On the other hand, when the double-sided color copying is performed in the conventional image forming apparatus as described above, the following problems occur.

That is, since the conventional fixing device is assumed to be a single-sided color copy, the pressure roller uses high strength rubber such as HTV silicone as its surface layer as described above.
Therefore, the surface roughness Rz of the pressure roller is Rz> 10 μm.
Will be. When double-sided copying is performed using such a pressure roller, the final back surface image (the surface that passes through the pressure roller side at the time of the second fixing) is rough, and the gloss and feel of the front and back surfaces of the transfer material, Furthermore, the problem that the color tone is different occurs.

Therefore, the object of the fourth aspect of the present invention is to eliminate the difference in gloss, touch, color and the like between the front surface and the back surface of the transfer material which has undergone double-sided copying and to obtain a good double-sided color copy. An object is to provide an image forming apparatus.

By the way, as a fixing roller used in a color electrophotographic apparatus, a roller having a small surface roughness (for example, an average surface roughness R in order to obtain high glossiness of an image).
z <10 μm roller) was used, and the roller was formed of the above-mentioned material so as to have a small surface roughness.

Further, it is desirable that the surface layer material of the pressure roller used in the image forming apparatus for performing double-sided copying has a high releasability like the surface layer material of the fixing roller.

Therefore, in a color electrophotographic apparatus for performing color two-sided copying, the same material is used as the surface layer material of the fixing roller and the pressure roller, and both rollers have the same surface roughness so that their surface roughness is small. It was molded by the method.

However, it has been found that when the fixing operation is performed using the fixing roller and the pressure roller, both of which have a small surface roughness as described above, both rollers are severely worn and their lifespan is shortened. This is because the surface roughness of both rollers is small, the adhesion of the pressure contact portion of both rollers is increased, and a shearing force is generated due to a slight difference in peripheral speed between the rollers, and this shearing force accelerates wear. It is believed that there is. The difference in peripheral speed between the two rollers occurs due to a difference in transmission peripheral speed due to gear drive and a difference in peripheral speed due to difference in elastic deformation of rubber.

When both rollers are worn, the service life of the rollers is shortened, and the pressure contact pressure between the rollers becomes non-uniform, causing paper wrinkles. In a typical electrophotographic apparatus that does not assume color double-sided copying, since a pressure roller with high strength and large surface roughness is used,
While the life of the fixing roller can withstand 100,000 copies, the life of the fixing roller is 20,000 in a conventional color electrophotographic apparatus having the same material and a small surface roughness fixing roller and pressure roller. Could only endure a copy of.

Further, when the surface roughness of both rollers is small, and when nothing is interposed between them, the adhesion force between both rollers surely rotates them without slipping, but paper or the like enters between them. Then, there is also a problem that slip easily occurs between the roller and the paper. This is because the surface roughness of the paper is very large, but the conveying force is reduced because the surfaces of both rollers have specularity.

When the above-mentioned slip occurs between the rollers, the amount of heat applied to the paper increases for a moment, causing image irregularities such as uneven gloss and streaks.

Therefore, the object of the fifth aspect of the present invention is to solve the problems such as the deterioration of durability and the occurrence of image distortion due to the wear of the fixing roller and the pressure roller, and to obtain a good double-sided color copy. An object is to provide an image forming apparatus.

[0067]

In order to achieve the above object, a first aspect of the present invention is provided with a fixing device for applying a releasing agent to a fixing rotator for fixing, and an image forming operation for fixing by the fixing device. In the image forming apparatus capable of continuously performing a plurality of times, a means for inhibiting the second and subsequent image forming operations of the resinous transfer material is provided.

The second invention is an image forming apparatus equipped with a fixing device for fixing an unfixed developer image transferred onto a transfer material by a fixing rotator coated with a release agent, wherein the transfer material is transferred. At least one of the path members that is supplied to and conveyed to the region and is in contact with the transfer material has a release agent absorbing layer for absorbing the release agent formed on the surface thereof.

The third invention is an image forming apparatus equipped with a fixing device for fixing an unfixed developer image transferred onto a transfer material by a fixing rotating body coated with a release agent, wherein the transfer material is transferred. At least one of the path members for supplying and conveying to the area is in contact with the transfer material, and the release agent absorbing layer and the release agent holding layer for absorbing the release agent are formed on the surface of the member. It is characterized by

A fourth aspect of the present invention is provided with a fixing device including a pair of upper and lower fixing rotators, forms an unfixed developer image on one surface of the transfer material, and uses the upper fixing rotator to form the image. After performing the first fixing by heating and melting the unfixed developer image,
An unfixed developer image is formed on the other surface of the transfer material, and the unfixed developer image is heated and melted by the upper fixing rotator to perform the second fixing, whereby the unfixed developer image is formed on both surfaces of the transfer material. In the image forming apparatus for forming an image, the surface roughness Rzu of the upper fixing rotator and the surface roughness Rzd of the lower fixing rotator of the fixing device are set to Rzu = Rzd. .

A fifth aspect of the present invention is provided with a fixing device including a pair of upper and lower fixing rotators, forms an unfixed developer image on one surface of the transfer material, and uses the upper fixing rotator to form the unfixed developer image. After performing the first fixing by heating and melting the unfixed developer image,
An unfixed developer image is formed on the other surface of the transfer material, and the unfixed developer image is heated and melted by the upper fixing rotator to perform the second fixing, whereby the unfixed developer image is formed on both surfaces of the transfer material. In the image forming apparatus for forming an image, the surface roughness Rzu of the upper fixing rotator and the surface roughness Rzd of the lower fixing rotator of the fixing device are set to Rzu <10 μm Rzu <Rzd. Characterize.

[0072]

According to the first aspect of the invention, since the second and subsequent image forming operations of the resinous transfer material having no water-absorbing property or oil-absorbing property as the transfer material are prohibited, each part when the resin-like transfer material is re-fed Transfer of the release agent to the apparatus is prevented, and a good image can always be obtained stably.

According to the second and third aspects of the present invention, the release agent attached to the first surface of the transfer material when the image of the first surface of the transfer material is fixed is fed and transferred to the transfer material when copying the second surface (during double-sided copying). Release agent absorbing layer (second invention) formed on the paper path member, and the release agent absorbing layer and the release agent retaining layer (third invention) are absorbed and held respectively, so that each part device at the time of re-feeding It is possible to prevent transfer of the release agent to the toner, and always obtain a stable double-sided image free from image stains and fog.

According to the fourth aspect of the invention, the surface roughness Rzu of the upper fixing rotator of the fixing device and the surface roughness Rzd of the lower fixing rotator are equal (Rzu = Rzd), so double-sided copying is performed. In addition, there is no difference in gloss, touch, and color tone between the front surface and the back surface of the transfer material, and a good double-sided color copy can be obtained.

According to the fifth aspect of the invention, between the surface roughness Rzu of the upper fixing rotator of the fixing device and the surface roughness Rzd of the lower fixing rotator, Rzu <10 μm and Rzu <Rz.
Since the relationship of d is established, problems such as deterioration of durability and occurrence of image distortion due to wear of both fixing rotating bodies are eliminated,
Good double-sided color copies are obtained.

[0076]

【Example】

[First Invention] An embodiment of the first invention will be described below with reference to the accompanying drawings.

<First Invention> FIG. 1 is a longitudinal sectional view of an electrophotographic apparatus according to the present invention, and FIG. 2 is a block diagram of a transfer material detection sensor. In FIG. 1, the conventional electrophotographic apparatus shown in FIG. The same elements as those of are denoted by the same reference numerals, and description thereof will be omitted below.

In this embodiment, the transfer material detection sensor S and the detector D are provided on the conveyance path 41 at the time of re-feeding, and the transfer material detection sensor S is connected to the light source L as shown in FIG. It is composed of a light receiving sensor P.

When a resin-like transfer material such as an OHP sheet enters the transport passage 41, this causes the detector D
Detected by. At this time, the transfer material detection sensor S
When the light from the light source L passes through the resin-like transfer material and is detected by the light receiving sensor P, it is determined that images are formed on both surfaces of the resin-like transfer material, and The image forming operation is stopped. In this case, the resinous transfer material remains in the transport passage 41,
By opening an opening / closing cover (not shown) provided in the vicinity of the tray 17, the resinous transfer material is taken out and collected from the inside of the apparatus main body without being damaged.

As described above, in the present embodiment, the second and subsequent image forming operations (re-feeding) of the resinous transfer material having no water absorption or oil absorption are prohibited, so that the resinous transfer material is adhered to the resinous transfer material. The transfer of the oil, which is the release agent, to the transfer system, the transfer drum 15, the photosensitive drum 19 and the like is prevented, and various problems associated with the oil retransfer are eliminated.

<Second Embodiment> Next, a second embodiment of the first invention will be described with reference to FIG. 3 is a vertical cross-sectional view of the electrophotographic apparatus according to the second embodiment. In this figure, the same elements as those shown in FIG. 15 are designated by the same reference numerals, and the description thereof will be omitted below.

In this embodiment, the transfer material detecting sensor S and the detector D are provided on the conveying path (paper feed guide) 7.

Then, the transfer material detection sensor S and the detector D detect that the resin-like transfer material such as the OHP sheet has entered the transport path 7, and the operation panel (not shown) gives an instruction for double-sided image copying. In this case, the resinous transfer material receives the first fixing by the fixing device 18 and is re-fed, and is discharged onto the tray 17 outside the apparatus without performing the second image forming operation.

As described above, also in this embodiment, since the second and subsequent image forming operations are prohibited for the resinous transfer material, the same effect as that of the first embodiment can be obtained.

<Third Embodiment> Next, a third embodiment of the first invention will be described with reference to FIG. Incidentally, FIG. 4 is a configuration diagram of the transfer material for sealing.

The present embodiment is an example of forming a multiple image by the electrophotographic apparatus according to the second embodiment (see FIG. 3).
As the transfer material, the transfer material P for sealing shown in FIG. 4 is used.

The transfer material P includes a release paper P1 and an adhesive P2.
And the resinous film P3, and the image is formed on the resinous film P3. Then, the release paper P1 is peeled off,
The resinous film P1 is attached to the adherend (not shown) by the adhesive P2.

However, since the transfer material P is not transparent as a whole, the light from the light source L is not detected by the light receiving sensor P in the transfer material detection sensor S, and the transfer material P is judged to be paper and is multiplexed. Image formation becomes possible.

Therefore, in this embodiment, as shown in FIG. 4, the tip portion C of the transfer material P for sealing is made of a transparent resin film. Therefore, in the transfer material detecting sensor S, the light from the light source L passes through the tip of the transfer material for sealing P and is detected by the light receiving sensor P. Therefore, the transfer material for sealing P is judged to be a resinous transfer material and is multiplexed. The conveyance to the image forming conveyance path is prohibited, and the sheet is discharged as it is from the fixing device.

By the above operation, the conventional problem that the oil, which is the release agent adhered on the transfer material at the time of fixing on one side, is transferred to each member inside the apparatus main body at the time of re-feeding, is solved, and in this embodiment. Also, the same effects as those obtained in the above-mentioned embodiment can be obtained.

<Fourth Embodiment> In the first invention, as shown in FIG. 5, the adjusting blade 144 of the fixing device 18 is tilted to increase the contact pressure of the adjusting blade 144 to the oil applying roller 143.
As a result, even if the amount of oil applied to the fixing roller 29 is 0.001 g / A4 (0.08 g / A4 in the embodiment) per A4 size transfer material, the above-described effect can be obtained. Also, the amount of oil applied is 0.0005 g / A4
Even in the case of, the damage to each part during re-feeding was hardly recognized.

By the way, the transfer material detecting sensor S and the detector D are not limited to the positions shown in the above-mentioned embodiment, but may be provided in the carrying path, in the cassette, or at any other position.

Further, as the method for detecting the resinous transfer material, in addition to the method according to the above embodiment, for example, a method in which a peculiar mark is attached to the resinous transfer material and this mark is detected by an image recognition device is adopted. You can Alternatively, a button for designating a resinous transfer material may be provided on the operation panel, and when the button is pressed, the second and subsequent image forming operations may be prohibited. [Second Invention] An embodiment of the second invention will be described below with reference to the accompanying drawings.

<First Embodiment> First, the structure of the fixing device 18 provided in the image forming apparatus according to the present invention will be described with reference to FIG. In FIG. 7, reference numeral 29 denotes a fixing roller, which is an aluminum cored bar 31 covered with HTV silicone rubber (high vulcanization type silicone rubber) 32 to a predetermined thickness, and an outer layer of LTV silicone rubber. The rubber (low vulcanization type silicon rubber) 33 is coated to a thickness of 200 μm, and the thickness of the rubbers 32 and 33 is 3 as a whole.
mm. A pressure roller 230 is provided below the fixing roller 29. The pressure roller 30 has an HTV silicone rubber 35 as an outer layer of a core metal 34 made of aluminum.
To a thickness of 1 mm, and a resin coating 3 on the surface layer.
5'is covered.

In the fixing roller 29 and the pressure roller 30, 400 W halogen heaters 36 and 37, which are heat sources, are provided.
Are arranged respectively. A thermistor 38 is brought into contact with the pressure roller 30, and the thermistor 38 turns on / off the current supply to the halogen heaters 36 and 37.
The FF is controlled. In this way, the surface temperatures of the fixing roller 29 and the pressure roller 30 are maintained at a predetermined value (for example, 170 ° C.) suitable for fixing the unfixed toner image 51 on the transfer material P to the transfer material P. It has become. The fixing roller 29 and the pressure roller 30 are rotationally driven in the direction of arrow b in the drawing by a driving device (not shown).

On the other hand, in order to improve the releasing property of the toner from the fixing roller 29, a releasing agent applying device 52 is provided at a predetermined position of the fixing device 18. This mold release agent application device 52 includes a silicone oil 53 in an oil tank 52a.
(Shin-Etsu Chemical dimethyl silicone oil KF96-300
cs) is pumped up by the roller groups 54 and 55, and the pumped silicone oil 53 is applied to the coating amount adjusting blade 45.
Regulated to a fixed amount by the silicone oil 53
Is applied to the fixing roller 29.

Further, the coating roller 55 is brought into contact with and separated from the fixing roller 29 by the plunger 43 and the spring 44.

FIG. 8 is a sectional view of the image forming apparatus according to the present invention. In this figure, the same elements as those shown in FIG. 15 are designated by the same reference numerals, and the description thereof will be omitted below.

In this embodiment, the pickup roller 101c, the paper feed guide 102a, and the registration roller 5a, which are transfer material supply / conveyance members, have the structure shown in FIG.

That is, in FIG. 6, 94 is a base,
This is made of metal, resin, hard rubber, ceramics or the like. A release agent absorbing layer 95 containing porous particles is formed on the base 94.

The thickness of the release agent absorbing layer 95 is preferably 10 μm or more from the viewpoint of the absorbability and the retaining ability of the release agent.

The particles contained in the release agent absorbing layer 95 have an average fine diameter of 0.01 to 2 μm and an average particle diameter of 0.1 to 0.1 μm.
50 μm is preferable, and silica, silica-alumina,
Inorganic materials such as alumina, mullite, and spinel can be used as appropriate. In this example, porous granulated silica particles having an average particle size of 20 μm were used. Further, a thermoplastic resin such as styrene-acrylic resin or a thermosetting resin was used as the binder resin, and the amount was 10 to 60 wt% with respect to the total amount of the particles. At this time, if the binder ratio in the mixing ratio of the particles and the binder is too small, the particles cannot be sufficiently bound on the substrate 94. It is not preferable because the coating agent is not coated, or sufficient voids cannot be maintained between the particles, so that the absorbing ability of the release agent is significantly reduced.

Thus, in this embodiment, the prepared mixture for the release agent absorbing layer 95 is stirred by using a usual disperser, TK type homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a coating liquid. The pick-up roller 1 is obtained by a known coating method.
01c, the paper feed guide 102a, and the surface of the resist roller 5a were coated and dried to a dry thickness of 100 μm, thereby forming a release agent absorbing layer 95. According to the microscope observation,
The release agent absorbing layer 95 was formed as a porous layer having voids in the porous particles as shown in FIG.

Thus, the pickup roller 101c having the release agent absorbing layer 95 formed on the surface thereof, and the paper feed guide 10
2a and the resist roller 5a were mounted on the multicolor electrophotographic copying machine shown in FIG. 8 and a double-sided copying experiment was conducted.

First, the transfer amount of silicone oil on the transfer material P in the fixing device 18 is set to 0.05 per A4 size sheet.
When double-sided copying was performed with g set, a good image was obtained from the first sheet, and a good image was obtained even when the original was changed and the second sheet was copied. No phenomenon was observed in which the silicone oil was transferred to the transfer drum 15 or the photosensitive drum 19, which is a transfer material carrier.

Even when the double-sided copying operation was repeated for 30,000 sheets, a good image free from image stains and fog due to transfer of silicone oil to the photosensitive drum 13 was obtained.

Furthermore, when the transfer amount of silicone oil to the transfer material P was set to 0.08 g per A4 size sheet and the same experiment was conducted, it was satisfactory even if the double-sided copying operation was repeated for 30,000 sheets. An image was obtained.

Further, when the release agent absorbing layer 95 after the durability double-sided copying was examined, it was confirmed that the silicone oil was effectively accumulated and retained in the porous particles and the voids between the particles.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to the accompanying drawings.

In this example, glass beads having an average particle size of 10 μm and spherical alumina fine particles having an average particle size of 1 μm were dispersed in a binder resin, and the same procedure as in the first example was performed.
Pickup roller 101c and paper feed guide 1 shown in FIG.
02a and the surface of the resist roller 5a are dried by a known coating method to a dry thickness of 100 μm,
The release agent absorbing layer 95 was formed.

According to the microscopic observation of the release agent absorbing layer,
As shown in FIG. 2, spherical alumina particles are scattered between the glass bead particles in the release agent absorbing layer 95,
It was confirmed that each of 5 was formed as a porous layer having large and small voids.

Thus, the pickup roller 101c having the release agent absorbing layer 95 formed on the surface thereof, and the paper feed guide 10
2a and the resist roller 5a were mounted on the multicolor electrophotographic copying machine shown in FIG. 8, and the same experiment as in the first embodiment was conducted.

First, the transfer amount of silicon oil on the transfer material P in the fixing device 18 is 0.08 per A4 size sheet.
When a double-sided copying operation was performed on 30,000 sheets with the value set to g, a good image without image stains and fog due to silicone oil was obtained, and the silicone oil was used as the release agent absorbing layer 95.
It was confirmed that the silicon oil was quickly absorbed and held, and the silicon oil was not transferred to the transfer drum 15 or the photosensitive drum 19 which is the transfer material carrier.

<Third Embodiment> Next, a third embodiment of the present invention will be described.

In this example, glass beads having an average particle size of 10 μm and amorphous alumina particles having an average particle size of 3 μm were dispersed in a binder resin, and the same procedure as in the first example was performed.
Pickup roller 101c and paper feed guide 1 shown in FIG.
02a and the surface of the resist roller 5a are dried by a known coating method to a dry thickness of 150 μm,
The release agent absorbing layer 95 was formed. Here, the irregular shape refers to a shape excluding a spherical shape and an elliptical shape, and usually refers to any crushed product.

According to the microscopic observation of the release agent absorbing layer 95, as shown in FIG. 10, in the release agent absorbing layer 95, amorphous alumina particles are scattered among the glass bead particles, and the release agent absorbing layer 95 is absorbed. It was confirmed that the layer 95 was formed as a porous layer having large and small voids, respectively.

Thus, the pickup roller 101c having the release agent absorbing layer 95 formed on the surface thereof, and the paper feed guide 10
2a and the resist roller 5a were mounted on the multicolor electrophotographic copying machine shown in FIG. 8, and the same experiment as in the first embodiment was conducted.

First, the transfer amount of silicone oil on the transfer material P in the fixing device 18 is 0.08 per A4 size sheet.
When the double-sided copying operation is repeated for 50,000 sheets after setting to g, a good image without image stains and fogging due to silicone oil is obtained, and silicone oil is used as the release agent absorbing layer 95.
It was confirmed that the silicon oil was quickly absorbed and held, and the silicon oil was not transferred to the transfer drum 15 or the photosensitive drum 19 which is the transfer material carrier.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described.

In this embodiment, the pickup roller 101
c and the resist roller 5a are made of porous ceramics to form a release agent absorbing layer 95, and the surface of the paper feed guide 102a is coated with porous granulated silica particles having an average particle diameter of 20 μm as in the first embodiment. The engineered one was used.

As the porous ceramics, alumina (Al ₂ O ₃ ) and cordierite (2MgO.2Al _2).
A porous sintered body such as O ₃ .5SiO ₂ ) is used.

Thus, the pickup roller 101c and the paper feed guide 10 on the surface of which the release agent absorbing layer 95 is formed.
2a and the resist roller 5a were mounted on the multicolor electrophotographic copying machine shown in FIG. 8, and the same experiment as in the first embodiment was conducted.

When the double-sided copying operation was performed on 80,000 sheets, a good image without image stains and fog due to silicone oil was obtained, and the silicone oil was used as the release agent absorbing layer 95.
It was confirmed that the silicon oil was quickly absorbed and held, and the silicon oil was not transferred to the transfer drum 15 or the photosensitive drum 19 which is the transfer material carrier.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described.

In this embodiment, instead of the pickup roller 101c and the resist roller 5a made of porous ceramics which is the release agent absorbing layer 95 in the fourth embodiment, a plastic porous sintered body (Sunfine AQ) is used.
-Asahi Kasei Kogyo Co., Ltd.) was used to perform the same experiment as in the fourth embodiment.

Even when the double-sided copying operation was repeated for 80,000 sheets, a good image free from image stains and fog due to silicone oil was obtained.

The releasing agent absorbing layer 95 in the present invention is not limited to the one described in the above embodiments, and other porous materials such as other particles or foam metal, or releasing agent absorbing body may be used appropriately. be able to. [Third Invention] An embodiment of the third invention will be described below with reference to the accompanying drawings.

<First Embodiment> In this embodiment, the pickup roller 101c, the paper feed guide 102a, and the registration roller 5a, which are the transfer material supply / conveyance members, have the structure shown in FIG.

That is, in FIG. 11, 94 is a base, which is made of metal, resin, hard rubber, ceramics or the like. A release agent holding layer 96 is formed on the base 94, and a release agent absorbing layer 95 containing particles is formed on the release agent holding layer 96.

The thickness of the release agent absorbing layer 95 is preferably 3 μm or more from the viewpoint of absorbency and retention of the release agent.

The particles contained in the release agent absorbing layer 95 have an average fine diameter of 0.01 to 2 μm and an average particle diameter of 0.1 to 2.
50 μm is preferable, and silica, silica-alumina,
Inorganic materials such as alumina, mullite, and spinel can be used as appropriate. In this example, porous granulated silica particles having an average particle size of 20 μm were used. Further, a thermoplastic resin such as styrene-acrylic resin or a thermosetting resin was used as the binder resin, and the amount was 10 to 60 wt% with respect to the total amount of the particles. At this time, if the binder ratio in the mixing ratio of the particles and the binder is too small, the particles cannot be sufficiently bound on the release agent holding layer 96, and if too large, the binder becomes rich and the particles become particles. Is not preferable because the pores are covered, or sufficient voids cannot be maintained between the particles, so that the release agent absorbability is significantly reduced.

On the other hand, the thickness of the release agent holding layer 96 is as follows.
From the viewpoint of the release agent retaining ability, it is preferably 3 μm or more, and dispersed particles have an average pore diameter of 0.01 to 2 μm and an average particle diameter of 0.1
In the same manner as the release agent absorbing layer 95, an inorganic material such as silica, silica-alumina, alumina, mullite, or spinel can be appropriately used.

In this example, as the particles contained in the release agent holding layer 96, spherical silica fine particles having an average particle diameter of 1.0 μm were used. As the binder resin, a thermoplastic resin such as styrene acrylic resin or a thermosetting resin is used as in the release agent absorbing layer 95, and the total amount of the particles is
It was prepared in the range of 10 to 60 wt%. In this case, if the binder ratio in the mixing ratio of the particles and the binder is too small, the particles cannot be sufficiently bound on the base 94, and if too large, the binder becomes rich and the pores of the particles become small. It is not preferable because the coating agent is covered, or sufficient voids cannot be maintained between the particles, so that the release agent retention is significantly reduced.

Thus, in this embodiment, the prepared mixture for the release agent holding layer 96 is dispersed by a ball mill for 10 minutes to obtain a coating liquid, and the pickup roller 1 shown in FIG.
01c, the paper feed guide 102a, and the surface of the resist roller 5a were coated and dried by a known coating method to a dry thickness of 100 μm to form a release agent holding layer 96.
According to a microscope observation, this release agent holding layer was formed as a porous layer having fine voids between the porous particles as shown in FIG.

Next, the prepared mixture for the release agent absorbing layer 95 is agitated for 3 minutes by using an ordinary disperser, TK type homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a coating liquid, which is then aired. The pickup roller 101c, the paper feed guide 102a, and the registration roller 5 are formed by a spray coating method.
A release agent absorbing layer 95 was formed by coating and drying the surface of the release agent holding layer 96 of a so as to have a dry thickness of 15 μm. still,
According to a microscope observation, the release agent absorbing layer 95 is formed as a porous layer having a large number of voids larger than those present in the release agent holding layer 96 between the porous granulated silica particles as shown in FIG. Was there.

By the way, the voids present in the release agent absorbing layer 95 and the release agent holding layer 96 have the following effects on the silicone oil (the same applies to other oils) as the release agent. That is, the silicone oil absorbed in the relatively large voids present in the release agent absorbing layer 95 is transferred to and absorbed by the small voids present in the release agent retaining layer 96 formed in the lower layer by the capillary phenomenon and retained. .

Thus, the pickup roller 10 having the release agent absorbing layer 95 and the release agent holding layer 96 formed on the surface thereof.
1c, the paper feed guide 102a and the registration roller 5a were mounted on the multicolor electrophotographic copying machine shown in FIG.

First, when the amount of silicon oil transferred to the transfer material P in the fixing device 18 (see FIG. 7) was set to 0.05 g per A4 size sheet, double-sided copying was performed.
A good image was obtained, and no phenomenon was observed that the silicone oil was transferred to the transfer drum 15 or the photosensitive drum 19, which is a transfer material carrier, during double-sided copying of the first sheet.

Even when the double-sided copying operation was repeated for 50,000 sheets, a good image free from image stains and fog due to transfer of silicone oil to the photosensitive drum 19 was obtained.

Further, the transfer amount of silicone oil to the transfer material P was set to 0.08 g per A4 size sheet, and the same experiment was carried out. As a result, the double-sided copying operation was repeated for 50,000 sheets. An image was obtained.

Further, when the release agent absorbing layer 95 and the release agent retaining layer 96 after the durability double-sided copying were examined, it was confirmed that the silicone oil was effectively accumulated and retained in the porous particles and the voids between the particles. Was done.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to the accompanying drawings.

In this embodiment, the average particle size is 1.2 μm.
The amorphous alumina fine particles of are dispersed in a binder resin,
Similar to the first embodiment, the pickup roller 101c, the paper feed guide 102a and the registration roller 5 shown in FIG.
The dry thickness is 100 μm on the surface of a by a known coating method.
The release agent-holding layer 96 was formed by coating and drying so as to have the following shape. Here, the amorphous shape means a shape excluding a spherical shape and an elliptical shape, and usually an arbitrary pulverized product.

Next, glass beads having an average particle size of 10 μm are mixed with a binder resin, and the mixture is stirred for 3 minutes by using an ordinary disperser, TK type homomixer (manufactured by Tokushu Kika Kogyo) to obtain a coating solution, The release agent holding layer 96 formed on the surfaces of the pickup roller 101c, the paper feed guide 102a, and the resist roller 5a by the air spray coating method.
The mold release agent absorbing layer 95 was formed by coating and drying the surface of the above so as to have a dry thickness of 15 μm.

The release agent absorbing layer 95 and the release agent holding layer 9 described above.
According to the microscopic observation of No. 6, as shown in FIG. 12, it is confirmed that a large number of minute voids are scattered in the releasing agent holding layer 96 and a relatively large number of relatively large voids are present in the releasing agent absorbing layer 95. Was done.

Thus, the pickup roller 10 having the release agent absorbing layer 95 and the release agent holding layer 96 formed on the surface thereof.
1c, the paper feed guide 102a and the registration roller 5a are mounted on the multicolor electrophotographic copying apparatus shown in FIG.
An experiment similar to the example was conducted.

First, the transfer amount of silicon oil to the transfer material P in the fixing device 18 is 0.08 per A4 size sheet.
When a double-sided copying operation was performed on 50,000 sheets with the value set to g, a good image without image stains and fog due to silicone oil was obtained, and silicone oil was used as the release agent absorbing layer 95.
It was confirmed that the silicone oil was quickly absorbed and held by the release agent holding layer 96, and the silicon oil was not transferred to the transfer drum 15 or the photosensitive drum 19 which is the transfer material carrier.

<Third Embodiment> Next, a third embodiment of the present invention will be described.

In this embodiment, the pickup roller 101
c and the resist roller 5a are made of porous ceramics to form the release agent holding layer 96, and the paper feed guide 102a has the same structure as that of the first embodiment.

Porous ceramics include alumina (Al ₂ O ₃ ) and cordierite (2MgO.2Al _2).
A porous sintered body such as O ₃ .5SiO ₂ ) is used.

Next, glass beads having an average particle size of 10 μm are mixed with a binder resin, and the mixture is stirred for 3 minutes by using an ordinary disperser, TK type homomixer (manufactured by Tokushu Kika Kogyo) to obtain a coating solution. A release agent absorption layer 95 was formed by coating and drying the surface of the release agent holding layer 96 of the pickup roller 101c and the resist roller 5a to a dry thickness of 15 μm by an air spray coating method.

Release agent absorbing layer 95 and release agent holding layer 9
According to the microscopic observation of No. 6, as shown in FIG. 13, it is confirmed that a large number of minute voids are scattered in the release agent holding layer 96 and a large number of relatively large voids are present in the release agent absorbing layer 95. Was done.

Thus, the pickup roller 10 having the release agent absorbing layer 95 and the release agent holding layer 96 formed on the surface thereof.
1c, the paper feed guide 102a and the registration roller 5a are mounted on the multicolor electrophotographic copying apparatus shown in FIG.
An experiment similar to the example was conducted.

First, the transfer amount of silicone oil onto the transfer material P in the fixing device 18 is 0.08 per A4 size sheet.
When a double-sided copying operation was performed on 100,000 sheets with g set to g, a good image without image stains and fog due to silicone oil was obtained, and silicone oil was used as the release agent absorbing layer 9
5 and the release agent holding layer 96 were quickly absorbed and held, and it was confirmed that the silicone oil was not transferred to the transfer drum 15 or the photosensitive drum 19 which is the transfer material carrier.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described.

In this embodiment, instead of the pickup roller 101c and the resist roller 5a made of porous ceramics which is the release agent holding layer 96 in the third embodiment, a plastic porous sintered body (Sunfine AQ) is used.
-A roller made of Asahi Kasei Corporation is used as a release agent holding layer 96.
Then, a release agent absorbing layer 95 similar to that of the third embodiment was formed on the release agent holding layer 96.

Thus, the pickup roller 10 having the release agent absorbing layer 95 and the release agent holding layer 96 formed on the surface thereof.
1c, the paper feed guide 102a and the registration roller 5a are mounted on the multicolor electrophotographic copying apparatus shown in FIG.
As a result of conducting an experiment similar to that of the embodiment, the double-sided copying operation is 1
A good image free from image stains and fogging due to silicone oil was obtained even after repeating for 0,000 sheets.

The releasing agent absorbing layer 95 and the releasing agent retaining layer 96 in the present invention are not limited to those described in the above embodiments, but other porous materials such as other particles and foamed metals, and releasing agents. A mold agent absorber can be used as appropriate. [Fourth Invention] An embodiment of the fourth invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 14 is a block diagram of a fixing device used in this embodiment, and the basic structure of the fixing device is the same as that of the conventional one.

However, in this embodiment, the surface layer material of the pressure roller 30 is different from the conventional one. That is, the pressure roller 30 has a 1 mm thick LTV silicone rubber layer made of the same material as the surface layer material of the fixing roller 29 on the aluminum cored bar 34. The fixing roller 29 and the pressure roller 30 are molded in the same manner, and both of the rollers 2
9 and 30 are molded by setting cores 31 and 34 in a mold, pouring LTV silicone rubber between the mold and the cores 31 and 34, and curing it.

As described above, the surface layers of the fixing roller 29 and the pressure roller 30 are both LTV silicone rubber, and both rollers 29 and 30 are molded by the same method, so that the surface roughness of both rollers 29 and 30 is improved. Are approximately equal (about 5 μm in this embodiment). That is, assuming that the surface roughness of the fixing roller 29 is Rzu and the surface roughness of the pressure roller 30 is Rzd, the following relations exist between them.

[0162]

## EQU3 ## Rzu = Rzd (1) holds.

When double-sided color copying is performed using the fixing device 18, both surfaces of the transfer material P have the same roughness, and there is no difference in gloss, touch, tint, etc. on the front surface and the back surface of the transfer material P. I was able to get a two-sided color copy.

<Second Embodiment> Next, a second embodiment of the second invention will be described.

Also in this embodiment, LTV silicone rubber is used as the surface layer material of the pressure roller 30.
Silicone rubber is a block polymer having a viscosity of 10 ⁵ poise and a vinyl end-capped linear dimethylpolysiloxane .. 40 parts by weight, whose constituent unit is a tetrafunctional todine segment and a bifunctional oil segment in the same molecule. A certain resin-like organopolysiloxane ... 60 parts by weight was used, and as the surface layer material of the fixing roller 29, the same material as the conventional one was used.

The method of molding the pressure roller 30 is the same as that described above, but the surface roughness after vulcanization changes due to a slight difference in the composition of the material, and the surface roughness R of the fixing roller 29 is changed.
zu = 5 μm, the surface roughness R of the pressure roller 30.
zd = 4 μm, and although there is a slight difference between the two, the above equation (1) was satisfied.

When double-sided color copying was performed using the fixing device 18 composed of the fixing roller 29 and the pressure roller 30, both surfaces of the transfer material P had the same roughness as in the first embodiment. There was no difference in gloss, touch, and color tone on the front and back surfaces, and good double-sided color copies could be obtained.

<Third Embodiment> Next, a third embodiment of the fourth invention will be described.

In this embodiment, the room temperature vulcanizing type RTV (KE140 manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the surface layer material of the fixing roller 29.
6) is used, the pressure roller 30 is used, a linear vinyl dimethylpolysiloxane having a viscosity of 10 ⁵ poise and a vinyl end blocked by vinyl chain, 40 parts by weight. A resin segment having a tetrafunctional structural unit and an oil segment having a bifunctional structural unit Resin-like organopolysiloxane, which is a block polymer in the same molecule, 40 parts by weight, and terminal dimethyl-blocked linear dimethylpolysiloxane having a viscosity of 100 poise, 20 parts by weight.

The pressure roller 30 was manufactured, cured and vulcanized by a conventionally known knife coating method.

Thus, in this embodiment, the surface roughness Rzu of the fixing roller 29 was Rzu = 7 μm, and the surface roughness Rzd of the pressure roller 30 was 6 μm, and the above equation (1) was substantially satisfied.

When double-sided color copying is performed using the fixing device 18 including the fixing roller 29 and the pressure roller 30, a good double-sided color copy can be obtained as in the first and second embodiments. did it.

By the way, in the above embodiment, both the surface roughness Rzu of the fixing roller 30 and the surface roughness Rzd of the pressure roller 30 are smaller than 10 μm (Rzu, Rzd <
The case of 10 μm) has been described, but this is because a glossy image is often required as a color image in general.

On the other hand, when the user requests a non-glossy color image, the fixing roller 29 and the pressure roller 30 are subjected to processing such as polishing so that their roughness Rzu, Rzd> 10 μm.
m (however, Rzu = Rzd) may be used, and the same effect as described above can be obtained by this.

By the way, generally, the surface roughness of the roller is likely to change depending on the processing method.

That is, according to the die processing method, the surface roughness of the roller tends to depend on the surface roughness of the inner surface of the die. In the knife coating method, the surface roughness of the roller is easily influenced by the viscosity of the rubber material and the aging time of the rubber surface after coating. Furthermore,
According to the spray coating method, the roller surface is relatively rough.

The surface roughness Rz of the roller used in the above description is based on the average surface roughness measuring method according to JIS-A.

Also, Rzu = R established between the surface roughness Rzu of the fixing roller 29 and the surface roughness Rzd of the pressure roller.
In the relationship of zd, it is not always necessary that Rzd and Rzd are numerically identical, and as an effect, the surface roughness Rzu, Rz of the fixing roller 29 and the pressure roller 30 is obtained.
d should be equal to each other, and as a result, the roughness of the image on both surfaces of the transfer material P should be equal. Therefore, it can be within a range satisfying such a requirement, and is several μm between Rzu and Rzd.
The difference is within the allowable range.

Further, as the material of the pressure roller 30, three examples are shown in the above-mentioned embodiment, but in consideration of the releasability and surface roughness of the pressure roller 30 in performing double-sided color copying, the pressure roller 30 is pressed. As a material of the roller 30, a resin having a terminal vinyl-blocked linear dimethylpolysiloxane having a viscosity of 10 ⁵ poise or more and two or more vinyl groups, and a structural unit containing at least one of tetrafunctionality and trifunctionality is used. An addition type silicone rubber elastic body obtained by curing a mixture having the organopolysiloxane is preferable.

By the way, it is more preferable that the material of the pressure roller 30 is the same as the surface layer material of the fixing roller 29.
This is because a material having a high releasability and a long life is selected as the surface material of the fixing roller. In the above example,
Although the fixing roller 29 has a two-layer structure and the pressure roller 30 has a one-layer structure, it goes without saying that the layer structure of both rollers 29 and 30 can be arbitrarily selected. [Fifth Invention] An embodiment of the fifth invention will be described below with reference to FIG.

<First Invention> The present invention relates to the following relationship between the surface roughness Rzu of the fixing roller 29 and the surface roughness Rzd of the pressure roller 30:

[0182]

## EQU4 ## Rzu <10 μm (2) Rzu <Rzd (3) is satisfied.

In this embodiment, the surface layer material and roughness of the pressure roller 30 are different from those of the conventional one. That is, the same surface layer material as that of the fixing roller 29 was used as the surface layer material of the pressure roller 30, and the pressure roller 30 was ground with a grindstone after molding.

As a result of the above, the surface roughness R of the fixing roller 29 is
zu is Rzu = 5 μm, while the pressure roller 30
The surface roughness Rzd was Rzd = 15 μm.

When double-sided color copying was performed using the fixing device 18 composed of the fixing roller 29 and the pressure roller 30 as described above, slippage was prevented from occurring when the transfer material (paper) was conveyed, and 100,000 sheets were transferred. Even when copying, both rollers are not scraped, the deterioration of durability due to wear of the fixing roller 29 and the pressure roller 30 and the occurrence of image distortion are eliminated, and a good double-sided color copy can be obtained.

<Second Invention> Next, a second embodiment of the fifth invention will be described.

In this embodiment, the fixing roller 29 and the fixing roller 30 are composed of a terminal vinyl-blocked linear dimethylpolysiloxane having a viscosity of 10 ⁵ poise. 40 parts by weight. A resin segment having a tetrafunctional structural unit and a bifunctional resin. A resin-like organopolysiloxane, which is a block polymer having an oil segment in the same molecule, 40 parts by weight, and a terminal vinyl-blocked linear dimethylpolysiloxane having a viscosity of 100 poise, 20 parts by weight.

When forming the surface layer of the fixing roller 29, a die method of manufacturing with a die having an inner mirror surface was used, and when forming the pressure roller 30, spray coating was used.

Thus, in this embodiment, the surface roughness Rzu of the fixing roller 29 was Rzu = 4 μm, whereas the surface roughness Rzd of the pressure roller 30 was Rzd = 18 μm, and the above equations (1) and (2) were established. .

When double-sided color copying was carried out using the fixing device 18 composed of the fixing roller 29 and the pressure roller 30 as described above, good double-sided color copying could be obtained as in the first embodiment.

<Third Embodiment> Next, a third embodiment of the fifth invention will be described.

In this embodiment, the same material as that of the first embodiment is used as the surface layer material of the fixing roller 29, and the pressure roller 3 is used.
A room temperature vulcanizing type RTV (KE1406 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a material of No. 0, and the pressure roller 30 was subjected to curing molding by a mold and then polishing.

Thus, in the present embodiment, the surface roughness Rzu of the fixing roller 29 is 5 μm, whereas the surface roughness Rzd of the pressure roller 30 is 12 μm, and the above equations (1) and (2) are satisfied. .

When double-sided color copying was carried out using the fixing device 18 composed of the fixing roller 29 and the pressure roller 30 as described above, good double-sided color copying could be obtained as in the first embodiment.

The surface roughness Rz of the roller used in the above description is based on the average surface roughness measuring method according to JIS-A.

Although three examples of the material of the pressure roller 30 are shown in the above embodiment, considering the releasability and surface roughness of the pressure roller 30 in performing double-sided color copying,
The pressure roller 30 is made of a material having at least one terminal vinyl-blocked linear dimethylpolysiloxane having a viscosity of 10 ⁵ poise or more and two or more vinyl groups, and the constitutional unit is at least one of tetrafunctional and trifunctional. An addition type silicone rubber elastic body formed by curing a mixture containing the resin-like organopolysiloxane is preferable.

By the way, it is more preferable that the material of the pressure roller 30 is the same as the surface layer material of the fixing roller 29.
This is because the material for the surface layer of the fixing roller 29 is selected to have high releasability and long life.

[0198]

As is apparent from the above description, according to the first invention, the second and subsequent image forming operations of the resinous transfer material having no water-absorbing property or oil-absorbing property as the transfer material are prohibited. It is possible to prevent transfer of the release agent to the respective devices when the sheet-shaped transfer material is re-fed, and always obtain a good image in a stable manner.

According to the second and third aspects of the present invention, the release agent adhered to the first surface of the transfer material at the time of fixing the image on the first surface of the transfer material is supplied to the transfer agent when the second surface is copied (duplex copying). The release agent absorbing layer (and the release agent retaining layer) formed on the paper path member absorbs and holds the release agent, which prevents transfer of the release agent to each device at the time of re-feeding, and prevents image stains and stains. A good double-sided image without fog can always be obtained stably.

According to the fourth invention, since the surface roughness Rzu of the upper fixing rotator of the fixing device and the surface roughness Rzd of the lower fixing rotator are equal (Rzu = Rzd), double-sided copying is performed. In addition, there is no difference in gloss, touch, color and the like between the front surface and the back surface of the transfer material, and a good double-sided copy can be obtained.

According to the fifth aspect of the invention, between the surface roughness Rzu of the upper fixing rotator of the fixing device and the surface roughness Rzd of the lower fixing rotator, Rzu <10 μm and Rzu <= R.
Since the relationship of zd is established, problems such as deterioration of durability and occurrence of image distortion due to wear of both fixing rotating bodies are eliminated, and a good double-sided color copy can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus according to a first embodiment of the first invention.

FIG. 2 is a configuration diagram of a transfer material detection sensor.

FIG. 3 is a sectional view of an image forming apparatus according to a second embodiment of the first invention.

FIG. 4 is a plan view of a transfer material for a seal.

FIG. 5 is a configuration diagram of a fixing device.

FIG. 6 is a schematic sectional view showing a release agent absorbing layer of the image forming apparatus according to the first embodiment of the second invention.

FIG. 7 is a configuration diagram of a fixing device of an image forming apparatus according to a second invention.

FIG. 8 is a sectional view of an image forming apparatus according to a second invention.

FIG. 9 is a schematic cross-sectional view showing a release agent absorbing layer of an image forming apparatus according to a second embodiment of the second invention.

FIG. 10 is a schematic sectional view showing a release agent absorbing layer of an image forming apparatus according to a third embodiment of the second invention.

FIG. 11 is a schematic cross-sectional view showing a release agent absorbing layer and a release agent retaining layer of the image forming apparatus according to the first example of the third invention.

FIG. 12 is a schematic cross-sectional view showing a release agent absorbing layer and a release agent retaining layer of an image forming apparatus according to a second example of the third invention.

FIG. 13 is a schematic cross-sectional view showing a release agent absorbing layer and a release agent retaining layer of an image forming apparatus according to a third example of the third invention.

FIG. 14 is a configuration diagram of a fixing device of an image forming apparatus according to fourth and fifth inventions.

FIG. 15 is a sectional view of a conventional image forming apparatus.

FIG. 16 is a perspective view of a transfer drum.

FIG. 17 is a diagram showing melting and softening characteristics of toner.

FIG. 18 is a configuration diagram of a fixing device of a conventional image forming apparatus.

FIG. 19 is a sectional view of a conventional image forming apparatus.

[Explanation of symbols]

 1 Image Forming Apparatus 5a Registration Roller (Path Member) 18 Fixing Device 29 Fixing Roller (Rotating Body for Fixing) 30 Pressure Roller (Rotating Body for Fixing) 94 Base 95 Releasing Agent Absorbing Layer 96 Releasing Agent Holding Layer 101c Pickup Roller (Path member) 102a Paper feed guide (Path member) D Detector P Transfer material S Transfer material detection sensor

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideo Kawamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Jiro Ishizuka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Ken Watanabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masahiro Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (10)

[Claims] 1. An image forming apparatus, comprising: a fixing device for applying a releasing agent to a fixing rotator for fixing, wherein the image forming operation for fixing by the fixing device can be continuously performed a plurality of times. An image forming apparatus comprising means for inhibiting the second and subsequent image forming operations of the resinous transfer material. 2. The image forming apparatus according to claim 1, wherein the amount of the release agent applied to the fixing rotary member is set to 0.001 g or more per A4 size transfer material. 3. An image forming apparatus comprising a fixing device for fixing an unfixed developer image transferred onto a transfer material by a fixing rotator coated with a release agent, wherein the transfer material is supplied to a transfer area. An image forming apparatus, wherein at least one of the members to be contacted with the transfer material among the conveying route members is formed with a release agent absorbing layer for absorbing the release agent on the surface thereof. 4. The image forming apparatus according to claim 3, wherein the release agent absorbing layer is a porous particle layer provided on a substrate. 5. The release agent absorbing layer is a layer containing at least one of spherical particles, amorphous particles and an aggregate of these particles provided on a substrate. Image forming apparatus. 6. An image forming apparatus including a fixing device for fixing an unfixed developer image transferred onto a transfer material by a fixing rotator coated with a release agent, the transfer material being supplied to a transfer area. At least one of the transfer path members that comes into contact with the transfer material is formed by forming a release agent absorbing layer for absorbing the release agent and a release agent holding layer on the surface thereof. Image forming apparatus. 7. The release agent absorbing layer is a layer containing at least one of porous particles, spherical particles, amorphous particles, and an aggregate of these particles provided on the release agent retaining layer. The image forming apparatus according to claim 6, wherein 8. The release agent-holding layer is a layer or a porous body provided on a substrate and containing at least one of porous particles, spherical particles, amorphous particles, and aggregates of these particles. The image forming apparatus according to claim 6, which is characterized in that. 9. A fixing device comprising a pair of upper and lower fixing rotators, an unfixed developer image is formed on one surface of a transfer material, and the unfixed developing is performed by the upper fixing rotator. After the first fixing, in which the developer image is heated and melted, an unfixed developer image is formed on the other surface of the transfer material, and the unfixed developer image is heated and melted by the upper fixing rotating body. In the image forming apparatus that forms an image on both surfaces of the transfer material by performing the second fixing, the surface roughness Rzu of the upper fixing rotator and the surface roughness of the lower fixing rotator of the fixing device. The image forming apparatus is characterized in that Rzd is set to Rzu = Rzd. 10. A fixing device comprising a pair of upper and lower fixing rotators, an unfixed developer image is formed on one surface of a transfer material, and the unfixed developing is performed by the upper fixing rotator. After the first fixing, in which the developer image is heated and melted, an unfixed developer image is formed on the other surface of the transfer material, and the unfixed developer image is heated and melted by the upper fixing rotating body. In the image forming apparatus that forms an image on both surfaces of the transfer material by performing the second fixing, the surface roughness Rzu of the upper fixing rotator and the surface roughness of the lower fixing rotator of the fixing device. The image forming apparatus is characterized in that Rzd is set to Rzu <10 μm Rzu <Rzd.