JPH02308289A - Image fixing device - Google Patents

Abstract

PURPOSE:To keep offset on a rotor for fixing from occurring early and to prevent an offset prevention layer from being peeled off by forming the offset prevention layer with oil absorption factor having a specified value to oil for releasing and adjusting the applying quantity of the oil for releasing. CONSTITUTION:In order to efficiently absorb applied silicone oil, the oil absorption factor of the offset prevention layer 20 to the silicone oil is set >=20wt%. The adjustment of the oil absorption factor of the offset prevention layer 20 to be a desirable value which is >=20wt% is performed by using rubber whose molecular weight of base polymer is large as LTV silicone rubber or RTV silicone rubber which constitutes the prevention layer 20 and properly adjusting the crosslinking degree of the molecular and the quantity of filling material such as filler, etc., which is mixed. Furthermore, the applying quantity of the silicone oil to the offset prevention layer 20 at the time of fixing is set to be small to be 0.001-0.5g per sheet by converting it into a recording material in A4 size. Thus, the offset prevention layer 20 is prevented from being peeled off from an oilproof layer 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image fixing device for fixing an unfixed image on a recording material in an image forming apparatus.

2. Description of the Related Art Electrophotographic image forming apparatuses capable of forming single-color images are known.

This image forming apparatus forms a latent image on a photoreceptor drum based on color separation signals of an original. For example, a full-color image can be formed on a recording material by coloring the I image with color toner to form a toner image, and then transferring the toner image to a recording material, which is repeated for each color one by one. The unfixed toner image formed on the recording material is fixed by an image fixing device installed within the image forming apparatus.

As shown in FIG. 5, this image fixing device consists of a fixing rotating body 1, a fixing roller 1 which is usually in the shape of a roller, a pressure roller 2 facing the fixing roller 1, and a silicone oil as a release agent applied to the fixing roller 1. and a fixing roller l.
A cleaning means 4 is provided for cleaning.

The fixing roller l is HT on a base material, usually a core metal 5 made of aluminum.
An elastic layer 6 made of V silicone rubber (high temperature vulcanizable silicone rubber) is formed, and an offset prevention layer 7 made of RTV silicone rubber (room temperature vulcanizable silicone rubber) is formed on the elastic layer 6. For example, the outer diameter is 40 mm.

The pressure roller 2 has an elastic layer 9 made of HTV silicone rubber formed on a core bar 8 made of aluminum, and a resin layer 10 made of fluororesin formed on the elastic layer 9, and similarly has an outer diameter of For example, it is 40 mm.

A halogen heater 11 is disposed inside the core metal 5 of the fixing roller 1 and the core metal 8 of the pressure roller 2. The temperature of the pressure roller 2 is detected by a thermistor 12 in contact with the temperature of the pressure roller 2, and the halogen heater 11 is activated. The temperature of the fixing roller 1 and the pressure roller 2 is kept constant at about 170° C. by on/off control.

The release agent applying means 3 applies a viscous [300
Apply the silicone oil 14 of C3 to the upper and lower supply rollers 15.
A and 15B pump up the liquid and apply it to the offset prevention layer 7 of the fixing roller l. Offset prevention layer 7
The amount of silicone oil applied to the upper supply roller 15
It is adjusted by the contact angle and pressure of the oil amount adjusting blade 16 brought into contact with A.

The cleaning means 4 removes toner offset from the offset prevention layer 7 of the fixing roller 1.

According to the fixing device as described above, the recording material P carrying an unfixed toner image T is transported in the direction of arrow a by a transport device (not shown), and the recording material P is moved in the direction of arrow a by a drive device (not shown). By passing the toner image T while being sandwiched between the fixing roller l and the pressure roller 2, which are rotated in the
is thermally fixed onto the recording material P.

However, in this fixing device, the elastic layer 6 of the fixing roller swells due to silicone oil as a release agent, and the nip between the fixing roller l and the pressure roller 2 increases. There was a problem that wrinkles were generated on the recording material P.

In order to solve such problems,
As disclosed in No. 31, a fixing roller with a multilayer structure has been proposed in which an oil-resistant layer made of fluororubber with high oil resistance is provided as an intermediate layer between an elastic layer and an anti-offset layer thereon. has been done.

According to this, the oil-resistant layer prevents the silicone oil applied to the anti-offset layer thereon from penetrating into the elastic layer below through the anti-offset layer, thereby preventing the first elastic layer from swelling. be able to. However, long...
However, since the adhesiveness of fluororubber is weak, it is difficult to form an anti-offset layer on the oil-resistant layer using various adhesives, or to form the anti-offset layer from one-component RTV silicone rubber with high adhesiveness. However, the adhesive strength of the anti-offset layer to the oil-resistant layer is not sufficient, which causes the following problems.

That is, the color toner used in a color image forming apparatus is
It is necessary to have good melting properties and color mixing properties when heat is applied, and a sharp-melt color toner with a low softening point and low melt viscosity is preferable, but such color toners have a high affinity, It is easy to offset the fixing roller, so a large amount of silicone oil is applied to the offset prevention layer of the fixing roller during fixing so that it is 0.6 g or more per sheet of A4 size recording material. However, because the amount of silicone oil applied is large, the silicone oil passes through the anti-offset layer and accumulates at the interface with the oil-resistant layer, and if the adhesive strength of the anti-offset layer to the oil-resistant layer is not sufficient, the anti-offset layer becomes oil-resistant. Peel from the layer.

Note that the amount of silicone oil applied is determined in a first-order manner.

In other words, the weight of 50 sheets of A4 size blank paper is A.

(g), the weight of 50 sheets of white paper after oil paper was placed between the fixing roller and the heating roller without transferring the image onto the white paper or applying silicone oil to the offset prevention layer of the fixing roller. Let B (g) be the weight of another 50 sheets of A4 size blank paper, and let Az (g) be the weight of another 50 sheets of A4 size white paper.The image is not transferred onto this white paper, but silicone oil is applied to the offset prevention layer of the fixing roller. If the weight of 50 sheets of blank paper after passing between the fixing roller and heating roller is C (g), then the amount of silicone oil applied per sheet of A4 size blank paper X (g) is: It is calculated as follows.

X= (c+a, -B-Az) 150 In order to prevent the anti-offset layer from peeling off from the oil-resistant layer, it is sufficient to reduce the amount of silicone oil applied, but the A4 size recording material obtained as described above If the amount of silicone oil applied per sheet is less than 0.5 g, a problem arises in that the life until offset occurs is shortened.

This is because the anti-offset layer is made of general RTV silicone rubber or LTV silicone rubber (low-temperature vulcanizable silicone rubber), so the oil absorption rate of the anti-offset layer is as low as 20wt%. As a result, the applied silicone oil is not absorbed very much by the anti-offset layer, and this combined with the small amount of silicone oil applied causes offset to occur early.

Note that the oil absorption rate of the offset prevention layer is determined as follows.

That is, dimethyl silicone oil L0OC3 (for example, Shin-Etsu Chemical KF96 100C3) is heated to 180°C, a rubber piece constituting the anti-offset layer is immersed in it, and the weight of the rubber piece before immersion is D (g). Then, measure the weight E (g) after 8 hours of immersion.

Obtained from oil absorption rate (%) = (E-D)/DX100.

Therefore, in view of the above-mentioned current situation, an object of the present invention is to provide an image that can be fixed well without early offset occurring in a fixing rotating body such as a fixing roller, and without peeling of the offset prevention layer. An object of the present invention is to provide a fixing device.

The above objects are achieved by the image fixing device of the present invention. In summary, the present invention provides a rotary body for fixing, which comprises an elastic layer formed on a base material, an oil-resistant layer made of fluororubber formed on the elastic layer, and an offset prevention layer formed on the oil-resistant layer. An image fixing device for fixing an unfixed image on a recording material, wherein the offset prevention layer has an oil absorption rate of 20 wt % or more for a release oil, and the offset prevention layer has a mold release rate when fixing to the offset prevention layer. The image fixing device is characterized in that the amount of oil applied is set to be 0.001 to 0.5 g per sheet of A4 size recording material.

According to the present invention, the amount of silicone oil applied during fixing to the anti-offset layer of the fixing rotor is reduced to o,oot~0.5g per sheet of A4 size recording material. This prevents oil from accumulating between the anti-offset layer and the oil-resistant layer below it, and prevents the anti-offset layer from peeling off from the oil-resistant layer. 20w
Since the amount is set at t% or more, even if the amount of silicone oil applied is small, the amount of oil absorbed by the offset prevention layer will not be insufficient, and offset will not occur early in the offset prevention layer.

111 cases One embodiment of the present invention will be described in detail below.

First, an image forming apparatus including an image fixing device of the present invention will be described.

FIG. 1 shows an example of an image fixing device according to the present invention. 1 is a configuration diagram showing an embodiment of an electrophotographic image forming apparatus capable of forming a full-color image by mixing toners of different colors; FIG.

This image forming apparatus has two main bodies 10 and 10, as shown in FIG.
0 (right side (II) in FIG. 1 to approximately the center of the apparatus main body 100), and
00, a latent image forming section (2) is provided near the transfer drum 18 that is rotatable in the direction of the arrow and constitutes the transfer material conveying system I; It basically consists of a developing means arranged close to the forming section H, that is, a rotary developing device m.

The transfer material conveyance system I includes transfer material supply trays 101 and 102 that are detachable from an opening formed on one side of the apparatus main body 100 (on the right side in FIG. 1), and these trays 101%.
0-5103.10 for paper feed located almost directly above 102
4, a paper feed guide 24a provided with paper feed rollers 106 and 107 at both ends disposed close to the chue2-rat t03.104, a paper feed guide 24b following this, and a paper feed guide 24b provided around the transfer drum 28. A transfer material contact roller 27, a gripper 26, a transfer material separation charger 22, and a separation claw 40 are provided in order from the lower end to the upper end in the rotational direction, and a transfer charger is provided inside the transfer drum 28. 29, a charger 23 for separating the transfer material, a conveyor belt means 25 provided above the paper feed guide 24a and close to the separation claw 4°, and a device located on the extension of the terminal end of the means 25 in the conveyance direction. It is provided to extend outside the main body 100. Device body 10
The image fixing device 121 according to the present invention is disposed between the conveyor belt means 25 and the discharge tray 41, and the image fixing device 121 is disposed between the conveyor belt means 25 and the discharge tray 41.

The P8 image forming section (2) includes an image bearing member, that is, a photosensitive drum 32, which is rotatable in the direction of the arrow, which is disposed on the road end of the transfer drum 28 in contact with it, and an image bearing member that rotates around the drum 32. A static eliminating charger 30 provided from the top end to the side end in the direction. It comprises a cleaning means 31, a second charger 33, and an image exposure means such as a laser beam for forming an electrostatic latent image on the outer peripheral surface of the photoreceptor drum 32, and an image exposure reflection means such as a polygon mirror. There is.

The rotary developing device m has a rotary body 3 consisting of a housing that can freely rotate twice.
4 and was mounted on the rotating body 34. It has a yellow developer 34Y, a magenta developer 34M, a cyan developer 34G, and a black developer 34BK, which are configured to visualize, that is, develop, an electrostatic latent image at a position facing the outer peripheral surface of the photoreceptor drum 32. ing.

The overall sequence of the image forming apparatus with the above configuration will be briefly explained using the case of full color mode as an example.
It is as follows.

That is, when the photosensitive drum 32 rotates in the direction of the arrow shown in FIG. 1 and the photosensitive layer on the drum 32 is uniformly charged by the primary charger 33, the laser beam modulated by the engagement of the yellow image of the original is generated. The image is exposed to light E, and an electrostatic latent image of a yellow image is formed on the photoreceptor drum 32). This electrostatic latent image of the yellow image is produced by the yellow image A, which has been fixed in advance at the developing position by the rotation of the rotating body 34 of the developing device (2).
- Developed by the developing device 34Y.

On the other hand, a transfer material (not shown) conveyed via the paper feed guide 24a, paper feed roller 1o6° and paper feed guide 24b
is held by the gripper 26 at a predetermined timing,
It is electrostatically wound around the transfer drum 28 by the abutting roller 27 and the electrode facing the abutting roller 27 . The transfer drum 28 rotates in the direction of the arrow shown in FIG. 1 in synchronization with the photoreceptor drum 32, and the visible image developed by the yellow developer 34Y is transferred between the outer peripheral surface of the photoreceptor drum 32 and the transfer drum. The image is transferred by the transfer charger 29 at the portion where the outer circumferential surface of the photoreceptor 28 is in contact. The transfer drum 28 continues to rotate and transfers the next color (magenta in FIG. 1).
Prepare for transcription.

On the other hand, the photosensitive drum 32 is neutralized by the neutralizing charger 3°, cleaned by the cleaning means 31, charged again by the primary charger 33, and subjected to image exposure as described above with the next magenta image signal. . The developing device (2) rotates while an electrostatic latent image based on the magenta image signal is formed on the photosensitive drum 32 by the above-mentioned [j light], and fixes the magenta developing device 34M at the developing position.

Perform predetermined magenta development, followed by 1. l: The above-described process is also carried out for cyan and black colors respectively, and when the transfer of the four colors is completed, the visible images of the four colors formed on the transfer material are neutralized by the respective chargers 22 and 23. , the gripper 26 releases the transfer material, and the transfer material is removed from the transfer drum 28 by the separation claw 40.
The image fixing device 12 is separated from the image fixing device 12 by the conveyor belt means 25.
1, where the toners are mixed and fixed by heat and pressure, completing a full-color printing sequence and forming the desired full-color print image.

Next, the developer used in the single image forming apparatus will be explained.

Color toner as a developer used in color image forming devices must have good melting properties and color mixing properties when heated, and it is necessary to use sharp-melt toner with a low softening point and short melting time. It is preferable to use such a sharp-melt toner, so that the color reproduction range of the copy can be widened and a color copy that is faithful to the original image can be obtained.

Such sharp melt toners are produced by melt-kneading, for example, polyester resin, styrene-acrylic resin, coloring agent (dye, sublimation dye), charge control agent, etc., pulverizing, and classifying. Various external additives can be added to the toner as needed.

Considering the offset resistance, fixing properties, and sharp melt properties of the color toner, it is particularly preferable to use a sharp melt polyester resin as the binder resin.The sharp melt polyester resin is synthesized from a diol compound and a dicarboxylic acid. The sharp melt color toner used in the image forming apparatus is a polymer compound having an ester bond in the main chain of the molecule, and the softening point of the sharp melt polyester resin is 60-150°C, preferably 80-120°C. ℃ is better.

The softening characteristics of this sharp melt color toner are shown in FIG.

Figure 2 shows a flow tester CFT-500 type (manufactured by Shimadzu Corporation) with a nozzle diameter of 0.5 mm and thickness of 1.0 mm, a load of 50 kg applied, and a preheating time of 300 at an initial temperature of 80°C. A plunger drop-to-temperature curve (hereinafter referred to as a softening S-shaped curve) of the toner drawn when the temperature was raised uniformly at a rate of 5° C./min after 2 seconds was obtained. The sample color toner used was 1 to 3 g of purified fine powder, and the plunger had a cross-sectional area of 1.

I used one from OC Go.

The softening S-shaped curve of color toner is as shown in FIG. That is, as the temperature is raised at a constant rate, the toner is gradually heated and begins to flow out (the plunger descends A).
4B), when the temperature is further increased, the molten toner largely flows out (B-C→D), and the plunger stops descending (D→E).

The height of the S-curve indicates the total amount of toner flow, and the height of the S-curve indicates the total amount of toner flowing out.
The temperature To corresponding to the point indicates the softening point of the toner.

The sharp-melt resin that provides such color toners has a melting temperature of T1.
When the temperature at which 5XlO' cp is shown is T2,
T,=90 N150℃, 1ΔTI=ITI-T2
It refers to a resin that satisfies the condition of i=5 to 30°C.

Sharp-melt resins having the temperature-melt viscosity characteristics described above are characterized by an extremely sharp decrease in viscosity when heated. This decrease in viscosity causes appropriate mixing of the top toner layer and the bottom toner layer of the color toner made of sharp-melt resin, and also rapidly increases the transparency of the toner layer itself, resulting in good color reduction. It causes mixing. Sharp melt color toners using such resins have a high affinity and are easily offset by the fixing roller.

Next, the image fixing device of the present invention will be explained.

FIG. 3 is a schematic configuration diagram showing an embodiment of the image fixing device of the present invention.

The present image fixing device is characterized by a fixing rotating body, that is, a fixing roller 17.The other configuration of the device is basically the same as that of the conventional image fixing device shown in FIG.
7, a release agent applying means 3 for applying silicone oil as a release agent to the fixing roller 17, and a cleaning means 4 for cleaning the fixing roller 17. Since these pressure rollers 2 and the like are the same as those of the prior art, their explanations will be omitted. Note that the same reference numerals in FIG. 3 as those in FIG. 5 indicate the same members.

The fixing roller 17 is mounted on a base material, usually a core bar 5 made of aluminum.
An elastic layer 18 made of TV silicone rubber is formed, and qa
An oil-resistant FFJ 19 made of fluororubber is formed on the adhesive layer 18, and an offset prevention Fa 20 made of LTV silicone rubber is formed on the oil-resistant layer 19. This offset prevention layer 20 has an oil absorption rate of 20 wt for silicone oil. % or more, and the amount of silicone oil applied to the anti-offset layer 20 during fixing is set to be 0.001 to 0.5 g per sheet of A4 size recording material.

Although various materials can be used for the elastic N18, HTV silicone rubber is suitable because it has excellent tensile strength, thermal conductivity, elastic modulus, and adhesiveness to the core bar 5. Preferably, HTV silicone rubber with high thermal conductivity is used. By making the first elastic layer 18 highly thermal conductive, heat can be rapidly supplied to the surface of the fixing roller 17, and the fixing roller 17 can be quickly supplied with heat when the recording material P passes through the fixing roller 17. This prevents the surface temperature of the recording material P from decreasing.
This is because the unfixed toner image T carried thereon can be fixed thermally stably.

Particularly when fixing a color image, the surface temperature of the fixing roller 17 has a large effect on color mixing, and changes in the surface temperature have an effect on changes in the tint of the color image. Therefore, it is particularly preferable to form the elastic layer 18 with HTV silicone rubber having a high thermal conductivity of 1.%.

Furthermore, it is also preferable to form the elastic layer 18 with methylphenyl HTV silicone rubber with high thermal conductivity, which is
This is because methylphenyl HTV silicone rubber has particularly excellent oil resistance, which further improves the oil resistance of the entire fixing roller 17.

In this example, the thermal conductivity of the elastic layer 18 is 0.5XiO-
"ca5L/cm*sec*"o, but more preferably 1.0X10-"ca/cm
About cm°C is good.

Oil-resistant 1#19 made of fluororubber is formed after applying a primer onto the elastic layer 18. The thickness of the oil-resistant layer 19 is preferably 5 to 300 JLm. If the thickness of the oil-resistant layer 19 is less than 5 JLm, there is a risk that the underlying elastic layer 18 may be partially exposed due to uneven coating of fluororubber. , the oil-resistant layer 19 is insufficient to prevent silicone oil from penetrating into the elastic layer 18. On the other hand, if it exceeds 300 pm, the hardness of the entire fixing roller 17 will increase, and the amount of thermal deformation of the fluororubber will be large, so when the fixing roller 17 is stopped for a long period of time, the contact with the pressure roller 2 will increase. This may cause deformation of the nip. Therefore, the thickness of the oil-resistant layer 19 is 5
A good range is 300 ILm, more preferably 8 to 1100 ILm.

Offset/) Prevention W! 20 is formed after applying a primer on the oil-resistant layer 19 as required.

The anti-offset layer 20 is preferably formed of a material that has good wettability with silicone oil as a mold release agent.
In addition to V silicone rubber, RTV silicone rubber can also be used. This RTV silicone rubber may be one-component or two-component, but preferably one-component RTV silicone rubber is used.
TV silicone rubber has adhesion to the other material before vulcanization, and the final offset prevention layer 20 has oil resistance N19.
This is because it can strengthen the adhesion with. A filler such as silica or petal may be appropriately mixed into the offset prevention layer 20, and conventionally known methods can be used for these methods.

A good method for forming the offset prevention layer 20 is to apply a rubber such as LTV silicone rubber or RTV silicone rubber by knife coating or spray coating.
The anti-offset layer 20 can be easily formed as a thin layer due to the free liquid surface of the coated rubber such as LTV silicone rubber or RTV silicone rubber, and the setting of manufacturing equipment etc. for forming the anti-offset layer 20 is easy, and the fixing roll can be easily set up. 1
This is because 7 is excellent in mass production. Further, the releasability of the offset prevention layer 20 is also stabilized.

As described above, the anti-offset layer 20 is formed after applying a primer on the oil-resistant layer 19 if necessary. As this primer, it is best to use a primer made of a silane coupling agent, etc., which has been conventionally generally used for adhesion of rubber, etc., but silicone varnish-based primers, mixtures of silicone varnish and silicone rubber, or block copolymer type primers may be used. A primer consisting of a silicone varnish may also be used.

In the present invention, the oil absorption rate of the silicone oil of the offset prevention layer 20 is set to 20 wt% or more for the following reason. That is, the oil absorption rate of the offset prevention layer 20 is set to 20.
By increasing the wt% or more, offset prevention layer 2
0 can be efficiently absorbed, and even if the amount of oil applied is reduced, the amount of oil absorbed by the offset prevention layer 20 will not be insufficient. Therefore, the releasability of the offset prevention layer This may lead to a decline.

Early occurrence of offset can be prevented.

In order to adjust the oil absorption rate of the offset prevention layer 20 to a desired value of 20 wt% or more, use a base polymer with a large molecular weight for the LTV silicone rubber or RTV silicone rubber that constitutes the prevention J#20, and Prevention layer 2
This may be carried out by appropriately adjusting fAfti for the degree of crosslinking in 0 and the amount of filler such as filler mixed inside.

In the present invention, the amount of silicone oil applied to the offset prevention layer 20 during fixing is 1 when converted to an A4 size recording material.
The reason why the amount is set to 1001 to 0.5 g per sheet is as follows.In other words, the amount of silicone oil per sheet of the offset prevention layer 20 is calculated as 1 when converted to an A4 size recording material.
If the coating amount exceeds 0.5 g per sheet, the amount of coating will be too large and it will not be possible to prevent the oil that has permeated through the anti-offset layer 20 from accumulating at the interface with the oil-resistant layer 19 below. , it is too small to apply less than 0.001 g, and even if the oil absorption rate of the offset prevention layer 20 is as high as 20 wt% or more, the amount of oil absorbed by the prevention layer 20 will be insufficient, and offset will occur early. cannot be prevented.

In order to reduce the amount of silicone oil applied to a desired value, the oil amount adjustment blade 16, which is in contact with the supply roller 15A on the release agent application means 3, is adjusted to the normal amount of oil shown in FIG. 4(A). The angle of contact of the blade 16 with the upper supply roller 15A is sharpened by tilting it by θ as shown in FIG. Make it large and adjust accordingly.

The image fixing device of this embodiment is configured as described above, and as in the conventional case, one recording material P carrying an unfixed toner image T is fixed.
The toner is transported by a transport device (not shown) in the direction of arrow a, and the recording material P is passed through while being sandwiched between a fixing roller 17 and a pressure roller 2, which are rotated in the direction of arrow A by a drive device (not shown). The image T is thermally fixed onto the recording material P.

According to the image fixing device of this embodiment, since the amount of silicone oil applied during fixing to the offset prevention layer 20 of the fixing roller 17 is reduced, there is a gap between the offset prevention layer 20 and the oil-resistant layer 19 thereunder. No oil accumulates in the
Therefore, the offset prevention N20 does not peel off from the oil-resistant layer 19.

In addition, since the oil absorption rate of Offset Prevention N20 is high, even if the amount of silicone oil applied is small, Offset Prevention M
J20 absorbs oil efficiently and does not cause insufficient oil absorption, and therefore does not cause early offset.

Although the case where the fixing rotating body is the fixing roller 17 formed in the shape of a roller has been described above, the present invention is not limited to this, and the fixing rotating body can also be formed in the shape of a belt.

Next, specific embodiments of the image fixing device of the present invention will be described.

An unfixed toner image on an A4 size recording paper was fixed using the image fixing device of the present invention described with reference to FIG. The oil absorption rate of the silicone oil of the offset prevention layer 2o made of LTV silicone rubber of the fixing roller 17 is 20 wt%, which is within the range of the present invention, and offset is prevented during fixing! The amount of silicone oil applied to #2o was 0.5 g per sheet of A4 size transfer paper, which was within the scope of the present invention.

As a result, even after fixing 10,000 sheets of recording paper, the fixing roller 17
The outer diameter remained unchanged at 40 mm, and even after fixing 30,000 sheets, the anti-offset HJ20 did not peel off from the oil-resistant FJ19, and no offset occurred, so good fixing was achieved.

On an oil-resistant layer similar to the oil-resistant layer 19 of the fixing roller 17, unlike the fixing roller 17, 18 wt% of LTV silicone rubber, which has a lower oil absorption rate and is outside the scope of the present invention, is applied to prevent offset. A fixing roller was obtained by forming layers. Then, by incorporating this fixing roller into an image fixing device similar to that shown in FIG. 3, the amount of silicone oil applied to the offset prevention layer during fixing can be reduced to 0.
．． The weight was set to 6 g and used for fixing.

As a result, after fixing approximately 10,000 sheets of recording paper, the offset prevention layer of the fixing roller peeled off from the oil-resistant layer.

Example 1 except that the amount of silicone oil applied to the offset prevention layer 20 during fixing of the fixing roller 17 was set to o, ooig, which is the lower limit of the range of the present invention per sheet of A4 transfer paper. Fixation was carried out under the same conditions as .

As a result, as in Example 1, even after fixing 30,000 sheets of recording paper, there was no peeling of the anti-offset layer 20 from the oil-resistant layer 19, and no offset occurred, resulting in good fixing. .

The amount of silicone oil applied to the offset/anti-offset layer 20 during fixing by the fixing roller 17 was set to 0,0007 g per sheet of A4 recording paper, which is less than the lower limit of the range of the present invention. Fixing was carried out under the same conditions as in Example 1.

As a result, offset occurred due to the fixing of 3,000 sheets of recording paper.

Fixing was carried out under the same conditions as in Example 1, except that the oil absorption rate of the silicone oil of offset prevention F#20 of the fixing roller 17 was set to 50 wt %, which is within the range of the present invention.

As a result, as in Example 1.2, even after fixing 30,000 sheets of recording paper, the offset prevention layer 20 from the oil-resistant layer 19
Good fixing was achieved with no peeling and no offset.

"Support 1" Fixing was carried out using the same oil absorption rate and silicone oil application amount as in Examples 1 to 3, except that one-component RTV silicone rubber was used for the anti-offset layer.
As with 3, good results were obtained.

Yo Xi! LA Fixing was carried out using the same oil absorption rate and silicone oil application amount as in Comparative Examples 1 and 2, except that one-component RTV silicone rubber was used for the anti-offset layer, and Comparative Example 1
Similar to -2, good results were not obtained.

Foresight 1 As explained above, according to the present invention, good fixing can be performed without early occurrence of offset on the fixing rotating body and without peeling of the offset prevention layer.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of an image forming apparatus equipped with an image fixing device of the present invention. FIG. 2 is a graph showing the softening characteristics of the sharp melt color toner used in the image forming apparatus shown in FIG. FIG. 3 is a schematic configuration diagram showing an embodiment of the image fixing device of the present invention. FIGS. 4A and 4B are explanatory diagrams showing a method of adjusting the amount of silicone oil applied in the image fixing device of FIG. 3, respectively. FIG. 5 is a schematic configuration diagram showing a conventional image fixing device. 2: Pressure roller 3: Release agent application means 17: Fixing roller 18: Elastic layer 19: Resin layer 20: Offset prevention layer 21: Image fixing'? 28: Transfer drum 32: Photosensitive drum Figure 2 Softening point Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1) An elastic layer is formed on a base material, an oil-resistant layer made of fluororubber is formed on the elastic layer, and an offset prevention layer is formed on the oil-resistant layer. In an image fixing device for fixing an unfixed image, the offset prevention layer has an oil absorption rate of 20 wt % or more for release oil, and the amount of release oil applied during fixing to the offset prevention layer is 20 wt% or more. , converted to A4 size recording material 1
An image fixing device characterized in that the image fixing device is set to have a weight of 0.001 to 0.5 g per sheet.