JP2000019880A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-glossiness color fixing device using a long-life roller resistant to the wrinkle and crack of a surface layer and the breakage and peeling of rubber without enlarging the device. SOLUTION: In this low-glossiness color fixing device 40 using the roller whose roller deformation is >=0.3 and where the rubber hardness of elastic layers 4 and 10 is <=20 deg., intermediate layers 5 and 11 using rubber whose hardness is higher than that of the layers 4 and 10 are provided between the layers 4 and 10 and surface mold-released layers 6 and 12, so that the roller has a long life to the wrinkle and crack of the surface layer, and the tensile strength of the rubber of the layers 4 and 10 is defined as 10 kg/cm2, so that it has a long life to the breakage of the rubber.

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 a copying machine, a laser beam printer, a facsimile, a micro film reader printer, and a recording machine, and has a characteristic in a fixing device.

More specifically, recording materials (electrofax sheets, electrostatic recording sheets, electrostatic recording sheets, Transfer material sheet,
A non-fixed toner image corresponding to the target image information is formed and supported on a surface of a printing paper or the like by a direct method or an indirect (transfer) method, and the unfixed toner image is recorded on a recording material surface carrying the image. The present invention also relates to an image forming apparatus provided with a fixing device that performs a heat fixing process as a permanently fixed image. In particular, the present invention relates to a color image forming apparatus including a fixing device that obtains a fixed image with low gloss.

[0003]

2. Description of the Related Art In recent years, a so-called low-gloss color image, in which the gloss of an image after fixing is low, has been preferred for text and business documents. As a color fixing device for obtaining such a low gloss color image, a color fixing device for obtaining a low fixing pressure by reducing the pressure at the nip portion by using a low hardness rubber to obtain a wide fixing nip width. Proposed.

FIG. 4 shows an example of the configuration of such a color fixing device.

The fixing roller 101 has a heater 102 as a heat source inside, a low hardness silicon rubber layer as an elastic layer 104 on a cored bar 103, and a release layer 106 on the surface.
As a fluororesin layer. Pressure roller 111
Has a heater 112 inside similarly to the fixing roller 101, and has an elastic layer 114 and a surface release layer on a mandrel 113.
16 are provided.

The thermistors 108 and 11 serving as temperature detectors are provided on the surfaces of the fixing roller 101 and the pressure roller 111, respectively.
8 are in contact with each other and the detected rollers 101, 111
The heaters 102 and 112 are driven by a heater drive circuit (not shown) based on the surface temperature of the roller, and the temperature control is performed so that the surface of each roller reaches a predetermined target temperature. Further, thermoswitches 109 and 119 as safety elements are provided near the fixing roller 101 and the pressure roller 111, respectively.

In this conventional example, the outer diameter of each of the fixing roller 101 and the pressure roller 111 is 40 mm,
The low-hardness rubber used as 4, 114 has a test piece hardness (JIS-A) of 1 ° and a tensile strength of 7 kg / cm.
Using ² rubber, the thickness of the elastic layer 104 is 2mm of the fixing roller 101, a wall thickness of 1.5mm of the elastic layer 114 of the pressure roller 111, as a fluorine resin of the surface layer the release layer 116, a 35μm thick A PTFE (polytetrafluoroethylene) coat is provided.

By using such a low hardness rubber, the fixing roller hardness is about 50 to 52 ° and the pressing roller hardness is about 60 to 62 ° (manufactured by Kobunshi Keiki Co., Ltd.
Sker-C hardness tester, when the total weight is 1 kg) and a low-hardness roller can be obtained. The nip width is 10.5 m at a pressure of 30 kg.
m and a wide fixing nip width with a low pressing force.

In this conventional example, since a fixing / pressure roller having a roller length of about 300 mm is used for A4 and letter size, the pressure at the nip is 30 kg / (1).
(0.5 mm × 300 mm) = 0.95 kg / cm ^{2 at} a low pressure, the unfixed toner image on the recording material is crushed at a high pressure in the fixing nip, and after fixing, the toner image surface becomes smooth and gloss is increased. Since this is prevented from increasing, a glossy image having a low gloss of about 10 to 25 (PG-3D manufactured by Nippon Denshoku Industries Co., Ltd., measured at 75 °) is obtained after fixing. (Fixing temperature 180 ° C, fixing speed about 1
20 / sec).

[0010]

However, in the above conventional example, a large nip width is obtained by using a low-hardness rubber as the elastic layer, so that the amount of roller deformation is large, resulting in the following problems. .

Since the roller deformation is large, the surface of the roller is extended with the deformation of the roller, so that wrinkles and cracks occur on the surface of the roller, and the life of the roller is short. In the case of this conventional example, surface layer wrinkles and the like occurred after approximately several thousand sheets passed.

Since the amount of deformation of the roller is large, the stress applied to the rubber layer of the elastic layer is large, and in the early stage of the durability, the rubber is broken or the rubber peels off, so that a roller having a long life cannot be obtained. In this conventional example, about 3,000 to 10,000 sheets are passed,
Rubber breakage occurred.

Note that the roller deformation amount is determined by using the outer diameter of the fixing roller as D ₁ (mm) and the outer diameter of the pressing roller as D ₂ (m).
m) and the nip width is d (mm).

Roller deformation (mm) = (D ₁ + D ₂ ) /
4-[{(D ₁ + D ₂ ) / 4} ² − (d / 2) ² ] ^1/2

If the hardness of the elastic layer is made sufficiently hard to solve such problems, the nip width becomes narrow, and the fixing property is deteriorated and the gloss of the fixed image is increased. Further, if the roller diameter is increased in order to obtain a wide nip width with a small amount of roller deformation, the fixing device itself becomes large.

Accordingly, a main object of the present invention is to provide an image forming apparatus provided with a low-gloss color fixing device using a roller having a long life with respect to surface wrinkles and cracks without increasing the size of the device. It is to be.

Another object of the present invention is to provide an image forming apparatus provided with a low-gloss color fixing device using a roller having a long life with respect to rubber breakage and peeling without increasing the size of the device. It is.

[0018]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
An image forming apparatus comprising: a color fixing device having a fixing roller and a pressure roller including an elastic layer and a surface release layer, and having a roller deformation amount of 0.3 or more and a rubber hardness of the elastic layer of 20 ° or less. The fixing roller and the pressing roller each include an intermediate layer between the elastic layer and the surface release layer, the intermediate layer using a rubber having a hardness higher than that of the elastic layer.

The tensile strength of the rubber of the elastic layer is 10 kg /
cm ² or more. It is preferable to provide a thin elastic layer between the intermediate layer and the surface release layer.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 2 shows an embodiment of a color image forming apparatus provided with a fixing device according to the present invention. In the color image forming apparatus of this embodiment, an intermediate transfer member is used.

In FIG. 2, a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a "photosensitive drum") 31 repeatedly used as a first image carrier has a predetermined peripheral speed (clockwise) as indicated by an arrow. (The process speed).

In the course of rotation, the photosensitive drum 31 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 32, and then exposed to image exposure means (not shown) for color separation of a color original image. By receiving the image exposure 33 by the image forming exposure optical system, an electrostatic latent image corresponding to a first color component image (for example, a magenta component image) of a target color image is formed.

Next, the electrostatic latent image is developed by a first developing device (magenta developing device) 41 with magenta toner (colored charged particles) M as a first color. At this time,
The fourth developing devices (cyan, yellow, and black developing devices) 42, 43, and 44 are in the operation-off state and do not act on the photosensitive drum 1, and the magenta toner images of the first color are the second to the second. 4 are not affected by the developing units 42 to 44.

The intermediate transfer roller 20 as the intermediate transfer member of the present embodiment includes a pipe-shaped core 21 and a medium resistance elastic layer 22 formed on the outer peripheral surface thereof. The elastic layer 22 of the medium resistance is made of silicon rubber, Teflon rubber, urethane rubber,
An electric material (volume resistivity) is adjusted to a medium resistance of 10 ⁵ to 10 ¹¹ Ω · cm by mixing and dispersing carbon or a metal oxide such as zinc oxide in an elastic material such as EPDM. It is a foamed layer.

The intermediate transfer roller 20 is a photosensitive drum 31
And is arranged in contact with the lower surface of the photosensitive drum 31 so as to rotate in the counterclockwise direction indicated by the arrow at the same peripheral speed as that of the photosensitive drum 31.

The intermediate transfer roller 20 is held in pressure contact with the photosensitive drum 31 with a predetermined pressing force. Between the photosensitive drum 1 and the intermediate transfer roller 20, a transfer nip portion as a transfer portion is provided. N is formed.

The toner used in this embodiment is, for example, a non-magnetic one-component toner having a volume average particle diameter of about 10 μm and a non-polar toner having a specific charge of about −25 μC / g. ing.

In the process in which the magenta toner image of the first color formed and held on the surface of the photosensitive drum 1 passes through the transfer nip portion N, the first magenta toner image From the bias power supply 61, the polarity (plus) opposite to the toner charging polarity (minus in this embodiment)
Is applied, and an intermediate transfer is performed on the outer surface of the intermediate transfer roller 20 by the electric field formed in the transfer nip area. In this embodiment, the applied voltage is between +2 kV and +5 kV.
It is.

After the transfer of the first color magenta toner image onto the intermediate transfer roller 20, the surface of the photosensitive drum is cleaned by the cleaning device 34.

Hereinafter, similarly,. Charge on the rotating photosensitive drum 31 → image exposure 33 corresponding to a second color component image (for example, a cyan component image) → second
Developing with cyan toner C of a developing unit (cyan developing unit) 42 → transferring the formed second color cyan toner image to the intermediate transfer roller 20 → cleaning the surface of the photosensitive drum 31 by the cleaning device 34; Charge on the rotating photosensitive drum 31 → image exposure 33 corresponding to a third color component image (for example, a yellow component image) → development with yellow toner Y of a third developing device (yellow developing device) 43 → formed third color Transfer of a certain yellow toner image to the intermediate transfer roller 20 → cleaning of the surface of the photosensitive drum 1 by the cleaning device 34; Charging of the rotating photosensitive drum 31 → Image exposure 3 corresponding to a fourth color component image (eg, a black (black) component image)
3 → Development of the fourth developing device (black developing device) 44 with black toner B → Transfer of the formed black toner image of the fourth color to the intermediate transfer roller 20 → Photosensitive drum 31
The four toner images (magenta, cyan, yellow, and black) are applied to the outer surface of the rotating intermediate transfer roller 20 by sequentially performing the cleaning by the surface cleaning device 34, the above-described image formation, and the transfer cycle. Are sequentially superimposed and transferred to form a composite color toner (mirror image) corresponding to the target color image.

A transfer roller 25 is arranged in parallel with the intermediate transfer roller 20 so as to be in contact with the lower surface of the intermediate transfer roller 20 and is arranged at the same peripheral speed as the intermediate transfer roller 20. Rotate in the direction.

The transfer roller 25 includes a cored roller 26 and
The elastic layer 27 is formed on the outer periphery of the elastic layer 27. In this embodiment, a medium-resistance elastic body is used.

In the process of sequentially transferring the toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer roller 20, the core metal 26 of the transfer roller 25 is supplied with the toner from the second bias power supply 29 for the transfer roller 25. Same polarity as (-)
Bias voltage is applied. This bias voltage generates an electric field that repels the toner image from the transfer roller 25 to the intermediate transfer roller 20, and prevents the transfer of the toner image on the intermediate transfer roller 20 to the transfer roller 25.

When the toner image on the photosensitive drum 31 is transferred to the intermediate transfer roller 20, the potential of the non-image portion is different from the potential of the toner image portion. Since the potential difference between the non-image portion 31 and the non-image portion is larger than the potential difference between the photosensitive drum 31 and the toner image portion, the transfer current flows more than the non-image portion.

This tendency is conspicuous when the resistance value of the intermediate transfer roller 20 is low. For example, when the current value to the non-image portion is more than twice the current value to the toner image portion, the non-image portion The electric field affects the toner image. That is, a low-resistance roller is not suitable for an intermediate transfer member.

Conversely, in the case of a roller having a high resistance, the electric field that can be generated by the bias power supply 61 becomes too small, and the intermediate transfer itself is impaired.

Therefore, a roller having a medium resistance in the range of 10 ⁵ to 10 ¹¹ Ω · cm, preferably 10 ⁷ to 10 ¹⁰ Ω · cm is suitable for the intermediate transfer member. When the elastic body 22 having a volume resistance value in this range is used, the above-described appropriate transfer current value can be set by applying +2 to +5 KV to the metal core 21.

The transfer of the first to fourth color toner images sequentially superimposed and transferred from the photosensitive drum 1 side to the intermediate transfer roller 20 side to the recording material 24 is performed by transferring the toner images to the intermediate transfer roller 20 from the sheet supply cassette 35 side. The recording material P separated and conveyed one by one by the paper feed roller 36 to the pressure contact nip portion n with the roller 25 is fed at predetermined timing through the registration roller 37 and the transfer guide 38, and the core metal of the transfer roller 25 26 from the second bias power supply 29 to the first
, And a transfer bias having a polarity (+) opposite to that of the toner is applied to the metal core 26.

The transfer bias has a larger absolute value than the bias of the polarity (+) opposite to that of the toner applied to the core 21 of the intermediate transfer roller 20 from the bias power supply 61. As a result, the toner image on the intermediate transfer roller 20 side is transferred to the recording material P side fed to the pressure nip n between the intermediate transfer roller 20 and the transfer roller 25. The recording material P to which the toner image has been transferred is introduced into the fixing device 40 via the guide 39.

When the recording material P passes through the pressure nip n,
A bias power source for the core metal 21 of the intermediate transfer roller 20 and a bias power source for the core metal 26 of the transfer roller 25 apply a bias having the same polarity (-) as the toner, respectively.
29.

By this bias switching, the transfer residual toner on the surface of the intermediate transfer roller 20 is returned to the surface of the photosensitive drum 31 and collected by the cleaning device 34, so that the intermediate transfer roller 20 is cleaned.

The toner adhering to the transfer roller 25 is also returned to the intermediate transfer roller 20, further returned to the photosensitive drum 31 and collected by the cleaning device 34, so that the transfer roller 25 is cleaned.

As described above, the intermediate transfer roller 20 is
2 is a medium resistance, the transfer residual toner can be sufficiently returned to the photosensitive drum 1 side by transfer of a bias (cleaning bias) having the same polarity as the toner to transfer the toner to the photosensitive drum 1 side to be in a cleaning state. It is not necessary, and the device configuration can be simplified.

The toner used in the present embodiment is a substantially spherical toner (hereinafter simply referred to as “polymerization”) produced by a polymerization method, containing 5 to 30% by weight of a low softening point substance and having a shape factor SF-1 of 100 to 110. Toner).

As the low softening point substance, ASTM D341
The maximum peak value of the subject measured according to 8-8 is 40 to 9
It is a compound showing 0 ° C. The measurement of the temperature of the maximum peak value of the polymerized toner is performed, for example, by using DSC-7 manufactured by Perkin Elemer Inc.
Is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. An aluminum pan was used as a sample, an empty pan was set as a control, and measurement was performed at a heating rate of 10 ° C./min. Specifically, paraffin wax, polyolefin, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax, derivatives thereof, or graft / block compounds thereof can be used. Preferably, the carbon number represented by the following general structural formula is 10
An ester wax having one or more long-chain ester moieties. Specific structural formulas of typical compounds of the ester wax are shown below as general structural formulas.

[0047]

Embedded image

The ester wax preferably used in the present invention has a hardness of 0.5 to 5.0. The hardness of the ester wax is a value obtained by preparing a cylindrical sample having a diameter of 20 mm and a thickness of 5 mm, and then measuring the Vickers hardness using a dynamic ultra-fine hardness tester (DUH-200) manufactured by Shimadzu Corporation. The measurement conditions were as follows: a load of 0.5 g, a load speed of 9.67 mm / sec, and a load of 10 μm.
After being displaced by m, it is held for 15 seconds, and the resulting dent shape is measured to determine Vickers hardness. The hardness of the ester wax preferably used in the present invention shows a value of 0.5 to 5.0. Specific compounds are represented by the following chemical formulas (1), (2),
The results are shown in (3) and (4).

[0049]

Embedded image

The shape factor SF1 here is a numerical value indicating the ratio of the roundness of the shape of the spherical material, and is the maximum length MXLNG of the elliptical figure formed by projecting the spherical material on a two-dimensional plane. Divide the square by the figure area AREA to get 100
It is represented by the value when multiplied by π / 4. That is, the shape factor SF1 is SF-1 = {(MXLNG) ² / AREA} ×
(100π / 4). Using a Hitachi FE-SEM (S-800), 100 toner images were randomly sampled, and the image information was obtained via an interface through an image analyzer (Luzex3) manufactured by Nicole.
And analyzed according to the above equation.

The cyan toner was adjusted as follows.
In a 21-liter four-necked flask equipped with a high-speed stirring device, 710 parts by weight of ion-exchanged water and 0.1 mol / 1-Na ₃
450 parts by weight of a PO ₄ aqueous solution were added, and the number of rotations was 12,000.
The rotation was adjusted, and the mixture was heated to 65 ° C. 68 parts by weight of a 1.0 mol / 1-CaCl ₂ aqueous solution is gradually added thereto,
A dispersion medium system containing a fine water-insoluble dispersant Ca ₃ (PO ₄ ) ₂ was prepared, while the dispersoid system was composed of 165 parts by weight of a styrene monomer and 35 parts by weight of an n-butyl acrylate monomer. I. Pigment Blue 15: 3 14 parts by weight Saturated polyester 10 parts by weight {teriphthalic acid-propylene oxide modified bisphenol A acid value 15, peak molecular weight: 6000} salicylic acid metal compound 2 parts by weight The following compound (maximum peak value 59.4 ° C.) 60 Parts by weight

[0052]

Embedded image

After the above mixture was dispersed for 3 hours using an attritor, a dispersion obtained by adding 10 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added to a dispersion medium. 15 while maintaining the rotation speed
Granulated for minutes. Thereafter, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, the internal temperature was raised to 80 ° C., and the polymerization was continued at 50 rotations for 10 hours. After the polymerization was completed, the slurry was cooled, and diluted hydrochloric acid was added to remove the dispersant.

After further washing and drying, the weight average diameter of the cyan toner measured by a Coulter counter is 6.
At 2 μm, the number variation coefficient was 27%, and SF-1 was 10%.
It was 4.

Similarly, a yellow toner, a magenta toner, and a black toner having SF-1 of 104 were produced. In addition, C.I.
I. Pigment Yellow 17 and magenta toner include C.I. I. As the pigment red 122 and the black toner, carbon black was used.

FIG. 1 is a schematic structural view of a color fixing device according to the first embodiment of the present invention.

The fixing roller 1 in this embodiment has a heater 2 (490 W / 127 in this embodiment) as a heat source.
V-rated product), a test piece hardness of 3 ° (JIS-A) and a tensile strength of 12 kg / cm ² as an elastic layer 4 on a core metal 3 of Al6063, thickness 2.5t. A silicon rubber layer having a thickness of 2.0 t was provided, and a silicon rubber layer having a test piece hardness of 60 ° (JIS-A), a tensile strength of 40 kg / cm ² , and a thickness of 0.25 t was provided thereon as an intermediate layer 5. A PFA (perfluoroalkyl, copolymer of perfluorovinylether and tetrafluoroethylene) coating layer having a thickness of about 20 μm is provided as a release layer 6.

The outer diameter of the fixing roller 1 is φ40, and the fixing roller hardness is about 60 ° (Asker-C hardness, 1
kg total weight).

The pressure roller 7 has a heater 8 (490
W / 127V rated product), Al6063, wall thickness 3.
A silicon rubber layer having a test piece hardness of 3 ° (JIS-A), a tensile strength of 12 kg / cm ² and a wall thickness of 1.5 t is provided as an elastic layer 10 on a core metal 9 of 0 t.
1 is a test piece hardness of 60 ° (JIS-A),
A silicon rubber layer having a tensile strength of 40 kg / cm ² and a thickness of 0.25 t is provided, and a PFA coating layer having a thickness of about 20 μm is provided as a release layer 12 on the surface layer.

The outer diameter of the pressure roller 7 is φ40, and a pressure roller hardness of about 65 ° is obtained.

The surfaces of the fixing roller 1 and the pressure roller 7 are contacted with thermistors 13 and 14 as temperature detectors, and based on the detected roller surface temperature, a heater driving circuit (not shown) The temperature control is performed so that the roller surface temperature becomes the temperature control target temperature.

Further, a thermoswitch 1 as a safety element
Reference numerals 5 and 16 are disposed in the vicinity of the respective surfaces of the fixing roller 1 and the pressure roller 7, and in this embodiment, a non-contact type thermoswitch is used to prevent the roller surface from being damaged.

As the fixing roller and the pressing roller, a roller having a roller length of about 30 mm is used, and the fixing roller and the pressing roller are pressed by a pressing spring (not shown).
A fixing nip width of about 9 mm is obtained with kgf.

Using the toner, a fixing speed of about 120
mm / sec, at a fixing temperature of 180 ° C., the gloss of the color image after fixing is about 10 to 30 (PDP manufactured by Nippon Denshoku Industries Co., Ltd.).
G-3D, gloss at 75 °).

Table 1 below shows the results of a study on the durability (surface wrinkles and cracks) of the roller when the rubber hardness of the elastic layer of the fixing roller and the pressure roller and the rubber hardness of the intermediate layer were changed.

[0066]

[Table 1]

When a roller without an intermediate layer is used (1),
(2) Coat wrinkles and cracks occurred in the early stage of durability. Further, in a roller without an intermediate layer, if the rubber hardness of the elastic layer is increased to improve durability (3),
The gloss of the image after fixing becomes high.

By providing the intermediate layer having a rubber hardness higher than that of the elastic layer, it was possible to prolong the service life against surface wrinkles and cracks (4) to (8).

Table 2 below shows the results of examination of the durability (rubber breakage, peeling) when the rubber strength of the elastic layer of the fixing roller and the pressure roller was changed.

[0070]

[Table 2]

In the case where the elastic layer had a rubber strength of 7 kg / cm ² (9), the rubber rupture occurred at about 10,000 to 20,000 sheets.

By using a rubber having a high rubber strength, it was possible to prolong the life of (10) and (11) regarding rubber breakage and peeling.

Therefore, in a low-gloss color fixing apparatus using a roller having a roller deformation amount of 0.3 or more and an elastic layer having a rubber hardness of 20 ° or less, an intermediate layer using a rubber having a higher hardness than the elastic layer is used. By providing such a structure, it was possible to prolong the service life of surface wrinkles and cracks.

By setting the rubber strength of the elastic layer to 10 kg / cm ² or more (preferably 12 kg / cm ² ), it was possible to prolong the life of the rubber against breakage and peeling.

In this embodiment, PF is used as the release layer.
Although the A coating layer was used, a PFA tube may be used.

Embodiment 2 FIG. 3 shows a case where the structure of the roller used in the fixing device of Embodiment 2 is applied to a fixing roller. The present embodiment is characterized in that a thin elastic layer 17 is provided between the intermediate layer 5 and the release layer 6 in the first embodiment.

In this embodiment, the test piece hardness is 10 °
(JIS-A), a silicon rubber layer having a thickness of about 200 μm is used as the thin elastic layer 17.

In Example 1, in particular, when rubber having a hardness of 50 ° or more is used as the intermediate layer 5, the hardness near the roller surface becomes hard, so that the adhesion to the recording material and the unfixed toner image deteriorates. However, in the present embodiment, the thin elastic layer 17 is provided to increase the adhesion between the recording material and the unfixed toner layer, thereby improving the fixing property. . Even if such a thin elastic layer is provided, there is no influence on wrinkles and cracks on the surface layer because of the shell of the intermediate layer.

In this embodiment, the case where the thin elastic layer is provided on the fixing roller has been described. However, the thin elastic layer can be similarly applied to the pressure roller, and the same effect as above can be obtained. it can.

[0080]

As is apparent from the above description, according to the present invention, in a low gloss color fixing apparatus using a roller having a roller deformation of 0.3 or more and a rubber hardness of an elastic layer of 20 ° or less. By providing an intermediate layer between the elastic layer and the surface release layer using a rubber having a higher hardness than the rubber of the elastic layer, it is possible to extend the service life against surface wrinkles and cracks. By setting the tensile strength of the rubber to 10 kg / cm ² , it is possible to extend the life of the elastic layer against rubber breakage, thereby obtaining a long-life fixing device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing one embodiment of a color image forming apparatus using the fixing device of the present invention.

FIG. 3 is a schematic configuration diagram of a fixing roller and a pressure roller used in a fixing device according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of a conventional fixing device.

DESCRIPTION OF SYMBOLS 1 Fixing roller 3, 9 Core 4, 10 Elastic layer 5, 11 Intermediate layer 6, 12 Surface release layer 7 Pressure roller 17 Thin elastic layer 40 Color fixing device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H030 AD04 2H033 AA11 AA25 BB05 BB06 BB15 3J103 AA02 AA15 BA41 FA09 FA12 FA19 GA02 GA57 GA58 GA60 GA66 HA03 HA12 HA22 HA53

Claims (3)

[Claims] An image forming apparatus comprising: a fixing roller including an elastic layer and a surface release layer; and a pressure roller.
In the image forming apparatus provided with a color fixing device in which the rubber hardness of the elastic layer is equal to or less than 20 °, the fixing roller and the pressure roller may have a rubber hardness of the elastic layer between the elastic layer and the surface release layer. An image forming apparatus comprising an intermediate layer using harder rubber. 2. The rubber of the elastic layer has a tensile strength of 10 kg.
^2. The image forming apparatus according to claim 1, wherein the ratio is not less than / cm ² . 3. The image forming apparatus according to claim 1, wherein a thin elastic layer is provided between said intermediate layer and said surface release layer.