JP2000284626A - Roll for hot press fixation and fixing device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a roll for fixing a toner with a low frictional surface layer by providing a specified surface hardness and a specified surface roughness to an elastic body containing a specified amount of spherical bodies having a specified average particle diameter. SOLUTION: The surface layer of the roll is an elastic body containing silicone rubber and/or fluororubber and 1-50 pts.wt. spherical bodies based on 100 pts.wt. elastic body. The spherical bodies have a higher hardness than the elastic body and 0.5-20 μm average particle diameter. The JIS-A hardness of the surface layer is <40 deg. and the 10-point average surface roughness is <=1.0 μm. An elastic layer 1b comprising HTV (millable type) silicone rubber is formed on a core metal 1a of a roll using aluminum as a substrate by way of a primer. An oil barrier layer 1c comprising fluororubber is formed on the elastic layer 1b by way of a primer and then a surface layer 1d is formed by way of a primer by casting a surface layer material in a cylindrical mold and hardening it by heat vulcanization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner fixing roller used in a heat and pressure fixing device of a toner image forming apparatus such as a copying machine, a printer, a facsimile, and the like. Suitable fixing rollers. The present invention also relates to a fixing device having such a toner fixing roller.

[0002]

2. Description of the Related Art Generally, a toner image forming apparatus such as a copying machine, a printer, and a facsimile has a device for applying heat and pressure to toner to fix the toner as a permanent image on recording paper. This is called a fixing device or a heat-pressure fixing device. In this heat and pressure fixing device, a pair of rotating members such as a heated roller and a roller, a film and a roller, and a belt and a roller are pressed against each other, and recording paper having unfixed toner is interposed between the rotating members. Nipped and transported. The pinched portion between the rotating bodies is called a nip. Unfixed toner is heated and softened in this nip,
A pressing force is applied to the recording paper, and after cooling and solidification, a permanent image of toner is formed on the recording paper.

Generally, the side in contact with the unfixed toner has various forms such as a roller, a film, and a belt. For example, in the case of a roller, it is called a fixing roller, an upper roller, a heat roller, or the like. On the other hand, the other side that does not come into contact with the unfixed toner is most commonly in the form of a roller, and is called a pressure roller, a lower roller, a backup roller, or the like.

[0004] These rollers are mounted on a metal roller core,
It is configured by laminating a heat-resistant elastic body in a single layer or a multilayer. In particular, the outermost layer of the elastic layer is called a surface layer.
Generally, examples of the elastic material used for the surface layer include silicone rubber and fluorine rubber. Silicone rubber and fluorine rubber have excellent heat resistance and chemical resistance, and when used as a material for a surface layer, can maintain their flexibility for a long period of time.

[0005] In addition to the above elastic body, a fluororesin may be used for the surface layer in some cases. Fluororesins are excellent in heat resistance and chemical resistance, have excellent non-adhesiveness, and have low friction and wear properties, but have high hardness and poor flexibility.

The flexibility of the surface layer affects the image quality after fixing. When the surface layer is flexible, that is, when the hardness is low, the toner easily follows the shape of the toner and is easily deformed.When the toner is pressed in the nip, the unfixed toner does not scatter around. Since the image can be fixed at a target place with high accuracy, a highly fine fixed image can be expected.

That is, in order to fix the toner with high image quality, a surface layer made of an elastic material is suitable, and elastic materials such as the aforementioned silicone rubber and fluorine rubber are suitable.

One of the characteristics required of the elastic body surface layer is toner releasability. The toner releasability refers to the difficulty in adhering the toner to the surface layer. If the toner easily adheres, that is, if the toner releasability is poor, the toner may be removed from the fixed image or the surface layer may not adhere. The toner adhered to the recording paper is fixed on the recording paper again, causing toner contamination. These are called toner offsets.

Particularly, since the surface layer of the fixing roller is in direct contact with the unfixed toner, a high toner release property is required.
In the double-sided image forming apparatus, the surface of the pressure roller is also required to have high toner releasability since the first surface, which has been fixed, comes into direct contact with the second surface when the second surface is fixed.

[0010] Therefore, it is desirable that the elastic material of the surface layer has as few fillers as possible or a non-filler which reduces the releasability of the toner. It is known that a filler having a reinforcing property generally has a high surface activity, and thus has a reinforcing property, but has a bad influence on the toner releasability.

However, when such a reinforcing filler is not contained, the surface layer is required to have improved surface friction. This is because, in many cases, contact parts such as a blade and a cleaning web come into contact with the surface layer, and the friction with these contact parts causes the surface layer to be worn or the contact parts to be worn. . Also, when the recording paper is nipped and transported by the nip, friction occurs between the recording paper and the surface layer, which may cause a similar problem. That is, in the case of high friction, the frictional force is increased and wear is likely to occur. Conversely, in the case of low friction, the frictional force is reduced and wear is less likely to occur.

Abrasion of the surface layer causes a problem such as scratches and irregularities on the surface of the surface layer, which are transferred to a toner image, causing image defects such as uneven gloss. In addition, if the release auxiliary oil is applied to the surface layer, oil unevenness is caused by scratches and unevenness caused by abrasion, and similarly, image defects such as uneven gloss are caused. In particular, when the amount of the reinforcing filler is small or when the filler is non-filler, the strength of the elastic body cannot be relatively increased.

As means for improving the frictional property of the surface layer, there is known an invention in which a spherical filler is filled in an elastic body, and spherical irregularities are formed on the surface layer to improve frictional property and reduce wear. Have been. For example, in Japanese Patent Application Laid-Open No. 8-193166, a spherical fused silica is added to an addition-reaction-type silicone rubber, and a moderately curved unevenness is formed on the surface of the fused silica. The target strength is improved, and the wear resistance is also improved. However,
In this method, the unevenness of the surface is indispensable in order to improve the wear resistance, and the greater the degree of the unevenness or the more the unevenness, the more the wear resistance is improved.

In Japanese Patent Application Laid-Open No. Hei 9-12893, addition type silicone rubber contains alumina and spherical tetrafluoroethylene resin to provide excellent heat conductivity, abrasion resistance and mold release durability to toner. An excellent composition is proposed. In the present invention, it is stated that the improvement of abrasion resistance is caused by the high slipperiness of the material itself and the formation of moderate hemispherical irregularities on the surface of the spherical tetrafluoroethylene resin. Have been. That is, for the same reason as described above, the more irregularities, the better the wear resistance.

[0015]

As described above, the surface layer of the toner fixing roller used in the heat and pressure fixing device is required to have low friction as well as toner releasability. However, in the existing invention, a low friction property is realized by forming a curved unevenness on the surface. However, this also impairs the smoothness of the surface.

Accordingly, it is an object of the present invention to provide a toner fixing roller having a low friction surface layer.

Another object of the present invention is to provide a toner fixing roller having a low friction surface layer, which is suitable for fixing high quality images.

It is a further object of the present invention to provide a toner fixing roller having a surface layer which is excellent in toner releasability and has uniform low friction.

Still another object of the present invention is to provide a fixing device used in a toner image forming apparatus, which can obtain a high quality toner image and has excellent durability of a toner fixing roller.

[0020]

The above object of the present invention is achieved by the following inventions (1) to (4).

(1) A roller for fixing a toner, which is used in a heat and pressure fixing device of a toner image forming apparatus, wherein a surface layer of the roller is an elastic material containing silicone rubber and / or fluorine rubber, The elastic body contains a spherical body having a higher hardness than the elastic body, and the spherical body is 0.5 to
The elastic body has an average particle diameter of 20 μm, and the elastic body contains 1 to 50 parts by weight of the spherical body per 100 parts by weight of the elastic body.
A roller for a heat and pressure fixing device, wherein the IS-A hardness is less than 40 ° and the surface has a 10-point average roughness (Rz) of 1.0 μm or less in the surface layer.

(2) The roller according to (1), wherein the silicone rubber is dimethyl silicone rubber.

(3) The roller according to the above (2), wherein the spherical body is spherical silica.

(4) A heating and pressing fixing device used in a toner image forming apparatus, comprising the heating and pressing fixing roller described in any one of (1) to (3) above. Fixing device.

In the invention of the above (1), by dispersing a spherical body having a higher hardness than the elastic body, when the elastic body is compressed, the elastic body may be filled with nothing, or the elastic body may be filled with a material other than the spherical body. It has lower friction than the case where it contains. this is,
By the fact that the spherical body with high hardness is dispersed in the elastic body,
At the pressure-welded interface, a local curved stress distribution occurs,
It is considered that this reduces the friction property with respect to the press contact surface. In addition, the spherical body dispersed therein can impart low friction properties when the average particle diameter is 0.5 μm to 20 μm. Further, when the spherical body has a ratio of 1 to 50 parts by weight with respect to 100 parts by weight of the elastic body, low friction properties can be imparted. Further, this low friction property is effectively exhibited when the hardness of the elastic body is relatively soft, and the hardness of the surface layer including the elastic body and the spherical body is more than 40 ° when measured by a method described later. When it is also small, sufficient low friction can be imparted.

That is, these functions do not obtain the effect of lowering the friction due to the unevenness of the surface as in the existing invention, but utilize the local curved stress distribution at the press-contact interface. Which is particularly effective for a relatively low hardness surface layer.

In the invention of the above (2), when the 10-point average roughness (Rz) of the surface layer is 1.0 μm or less, after fixing, a high quality toner image having sufficient glossiness visually can be obtained. Can be

In the above invention (3), dimethyl silicone rubber, which is a low-hardness elastic body having excellent toner releasability, is used as the silicone rubber, and the spherical body is dispersed in the dimethyl silicone rubber to impair the characteristics of the dimethyl rubber. Low friction can be imparted to the roller surface layer without any problems.

In the invention of the above (4), by using silica having high compatibility with dimethyl silicone rubber as the spherical body, the spherical body can be well dispersed in the dimethyl silicone rubber, and the low friction property can be uniform. A toner fixing roller having the applied surface layer is obtained.

In the above invention (5), a high-quality toner image can be obtained by using a toner fixing roller having a low friction surface layer having excellent toner release properties, and a toner fixing property. A fixing device having excellent roller durability can be provided.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The surface layer of the toner fixing roller of the present invention is formed of an elastic material selected from silicone rubber, fluorine rubber or a composite thereof. As the silicone rubber, organopolysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, methylvinylpolysiloxane, and methylfluoroalkylpolysiloxane are used.Since dimethylpolysiloxane rubber has excellent toner releasability and low hardness, preferable. These silicone rubbers may be of a millable type or a liquid type.

As the fluorine rubber, vinylidene fluoride
Propylene hexafluoride copolymer, ethylene tetrafluoride-propylene copolymer, vinylidene fluoride-propylene hexafluoride-ethylene tetrafluoride terpolymer, ethylene tetrafluoride-vinylidene fluoride-propylene terpolymer A polymer or the like is used.

As the composite of silicone rubber and fluororubber, those containing 20 to 80% by weight of silicone rubber in the composite are preferably used. In particular, silicone rubber is used as the sea phase, and fluororubber is used as the island phase. A dispersion having a sea-island structure is preferably used. Such a composite comprises a silicone rubber and a fluororubber, preferably 100
It is obtained by kneading under heating conditions of ° to 250 ° C.

Examples of the sphere used in the present invention include spheres such as silica, alumina, magnesium oxide and beryllium oxide. Spherical silica is particularly preferred in view of compatibility with dimethylpolysiloxane rubber. The average particle size of the spheres is in the range of 0.5 to 20 μm, but is particularly preferably in the range of 0.8 to 12 μm.
Within these ranges, low friction can be imparted to the elastic body.

The content of the spherical body in the elastic body is determined by the elastic body 10
1 to 50 parts by weight, preferably 5 to 5 parts by weight.
The range is 40 parts by weight.

In the present invention, the JIS-A hardness of the surface layer (according to JIS K6301 type A hardness test) is 40.
And is preferably in the range of 5 to 36 °. Within this range, a sufficiently low friction can be imparted to the elastic body.

In the present invention, JIS of the surface of the surface layer
10 point average roughness (Rz) according to B0601 is 1.0
It is preferably not more than μm. With this Rz value, a high-quality toner image having sufficient glossiness visually can be obtained.

The toner fixing roller of the present invention can be manufactured, for example, as follows. That is, a vulcanizing agent, a vulcanization aid and the like are added and mixed at a temperature equal to or lower than the vulcanization temperature to a silicone rubber in which a predetermined amount of spherical bodies are dispersed, a fluororubber or a composite thereof, and the obtained mixture is The outer periphery of a roller core (a silicone rubber layer or a fluoro rubber layer may be provided) that has been uniformly coated with a primer and dried in advance is press-molded by transfer using a mold so as to become a surface layer, and the mold is added. It is manufactured through the steps of vulcanization, demolding, secondary vulcanization and polishing. As the vulcanizing agent and the vulcanizing aid, those known to those skilled in the art can be selected and used. In addition, colorants, ultraviolet absorbers, foaming agents, and the like well known to those skilled in the art can be appropriately compounded as necessary.

In order to disperse a spherical body having a hardness higher than that of the elastic body, the elastic material is mixed with a single mixer such as a static mixer, a two-roll mixer, a three-roll mixer or a kneader mixer. Or by using them in combination.

The formation of the surface layer is not limited to press molding by transfer using a mold, but may be carried out by a method known to those skilled in the art, such as molding by coating, molding by dipping, and application molding by spraying. Also,
This does not impair the effects of the present invention.

[0041]

EXAMPLES The present invention will be described in detail with reference to the following Examples, which do not limit the present invention in any way.

<Structure of Toner Fixing Roller> To verify the effects of the present invention, the following toner fixing roller was manufactured. First, on a roller core 1a having an outer diameter of 58 mm using aluminum as a base material, via a primer,
An elastic layer 1b made of HTV (millable type) silicone rubber having a thickness of 2 mm was formed. Thereafter, an oil barrier layer 1c made of fluoro rubber and having a thickness of 50 μm was formed on the elastic layer via a primer. Finally, on this oil barrier layer, a surface layer 1d is coated with a primer by applying a surface layer material of an example described later or a surface layer material of a comparative example to a thickness of 200 μm in a cylindrical mold via a primer. After the mold, it was formed by using a means of curing by heat vulcanization.

As a means for dispersing a spherical body or an irregularly shaped body in an elastic body as a material of the surface layer, an uncured elastic body material is stirred by a static mixer, and the spherical body or the irregularly shaped body is stirred. Add slowly, stir and mix,
After mixing the whole amount, mixing was carried out by a three-roll mixer to complete the dispersion.

In the following Examples and Comparative Examples, when spherical silica was dispersed in dimethyl silicone rubber, a composition having good dispersibility and a uniform dispersion state, and a vulcanized cured product thereof were obtained. .

<Heating / Pressing Fixing Apparatus> FIG. 1 shows the configuration of a heating / pressing fixing apparatus used to verify the effects of the present invention. In the heat and pressure fixing device, the toner fixing roller prepared by the above method was used as the fixing roller 1 and the pressure roller 2. At the center of each roller, a heater 3 composed of a halogen lamp is located.
The output of the heater 3 of the fixing roller 1 and the pressure roller 2 is controlled based on the temperature measured by a temperature measuring element (not shown) in contact with the surface, and is maintained at a set temperature. An oil application roller 4 is in contact with the fixing roller 1 and is driven by the fixing roller. The oil application roller 4 applies a fixed amount of release assist oil to the surface of the fixing roller. The fixing roller 1 has an elastic blade 5 and the pressure roller 2 has
The elastic blade 6 is pressed. In these elastic blades, one corner of an edge parallel to the long axis is pressed against the roller surface with a constant pressure.

<Method for Measuring Surface Roughness, Hardness, and Strength> The surface roughness is defined as the surface roughness of the roller and is defined by JIS B 0601.
Was measured based on the 10-point average roughness (Rz).
Further, the same material as the surface layer of the roller was vulcanized and formed into a sheet having a thickness of 10 mm, and the measurement was performed according to the A-type hardness test (JIS-A) of JIS K6301. The mechanical hardness was measured in accordance with JIS K6301 by setting the tensile strength of a sheet molded product in the same manner as the hardness.

<Evaluation of Roller Performance (Image Quality)> Roller performance (image quality) was evaluated by passing an unfixed black solid toner image through a heating and pressing fixing device and visually checking unevenness in toner gloss of the fixed image. . For the unfixed black solid toner image, a color laser copier 800 manufactured by Canon Inc. is used to set a black image on the document reading table, the copy operation setting is set to the 4-color full color mode, and the copy operation is performed. The recording paper to which the unfixed toner was transferred was taken out before fixing. The heating / pressing fixing device was set in an external idle rotating machine, and the temperature and rotation speed of the fixing roller and the pressing roller were controlled to pass the unfixed black solid toner image. The external idle rotating machine is a machine that operates the heating and pressing fixing device, and includes a motor for rotating the fixing roller and the pressing roller, and a control device for controlling the temperature and the number of rotations of the motor. When passing a black solid toner image, set the temperature to 1
The temperature was set to 70 ° C. and the number of rotations of the roller was set to 40 r. p. m. Set to.

The evaluation of the roller performance (image quality) was performed using an unused roller and a roller after a wear durability test.
The abrasion endurance test was conducted by evaluating the temperature of the unused roller at a temperature of 200 ° C. and the rotation speed of 40 r. p. m. As 100
This was performed by idling for an hour. As described above, since the elastic blade is pressed against the roller, the heat and pressure fixing device used in the present embodiment is subjected to the above-mentioned idle rotation test. Can be performed. The roller performance (image quality) of an unused roller and a roller after a wear durability test are compared, and various rollers are evaluated under the same conditions to compare the wear durability, in other words, the superiority of friction. Can do things.

Example 1 A roller was formed using the following composition as a material for a surface layer. For 100 parts by weight of unvulcanized dimethyl silicone rubber A (tensile strength after vulcanization = 20 kgf / cm ² ), spherical silica having an average particle size of 0.8 μm (Tospearl, manufactured by Toshiba Silicone Co., Ltd.) 108) was added and dispersed, and primary vulcanization was performed at 130 ° C. for 30 minutes.
Secondary vulcanization was performed at 0 ° C. for 2 hours to complete the vulcanization. These vulcanization conditions are set as standard conditions.

Example 2 A roller was formed using the following composition as a material for a surface layer. To 100 parts by weight of unvulcanized dimethyl silicone rubber A, 30 parts by weight of spherical silica having an average particle diameter of 3 μm (Tospearl 130, manufactured by Toshiba Silicone Co., Ltd.) was added.
It was dispersed and vulcanized under standard conditions.

Example 3 A roller was formed using the following composition as a material for the surface layer. To 100 parts by weight of unvulcanized dimethyl silicone rubber A, 5 parts by weight of spherical silica having an average particle diameter of 12 μm (Tospearl 3120 manufactured by Toshiba Silicone Co., Ltd.) was added and dispersed under standard conditions. Vulcanization was performed.

Comparative Example 1 A roller was formed by vulcanizing under standard conditions using only dimethylsilicone rubber A as the material of the surface layer.

Comparative Example 2 Dimethyl silicone rubber B (tensile strength after vulcanization = 3
Only 4 kgf / cm ² ) was used as a surface layer material and vulcanized under standard conditions to form a roller.

Comparative Example 3 A roller was formed using the following composition as a material for a surface layer. To 100 parts by weight of unvulcanized dimethylsilicone rubber A, 10 parts by weight of reinforcing irregular-shaped silica (R972, manufactured by Nippon Aerosil Co., Ltd.) was added, dispersed, and vulcanized under standard conditions. Was.

Comparative Example 4 A roller was formed using the following composition as a material for the surface layer. To 100 parts by weight of unvulcanized dimethyl silicone rubber A, 20 parts by weight of spherical silica having an average particle diameter of 12 μm (Tospearl 3120, manufactured by Toshiba Silicone Co., Ltd.) is added and dispersed, and primary vulcanization is performed. The vulcanization was performed at 180 ° C. for 30 minutes with the secondary vulcanization being the same as the standard condition.

Comparative Example 5 Dimethyl silicone rubber C (tensile strength after vulcanization = 4
Only 5 kgf / cm ² ) was used as a surface material and vulcanized under standard conditions to form a roller.

Comparative Example 6 A roller was formed using the following composition as a material for the surface layer. To 100 parts by weight of unvulcanized dimethyl silicone rubber C, 20 parts by weight of spherical silica having an average particle diameter of 12 μm (Tospearl 3120, manufactured by Toshiba Silicone Co., Ltd.) was added and dispersed under standard conditions. Vulcanization was performed.

The hardness of the surface can be adjusted by the kind of the elastic polymer. Further, the magnitude of Rz can be adjusted by the vulcanization conditions (temperature × time) of the primary vulcanization.

Table 1 shows the surface roughness and hardness of the roller surface layer obtained in each of the examples and comparative examples.
It was shown to. In addition, the evaluation results of the performance of unused rollers and the evaluation results of the performance of the rollers after the abrasion durability test were
The results are shown in Table 2.

[0060]

[Table 1]

[0061]

[Table 2] As can be seen by comparing the results of Examples 1 to 3 and Comparative Example 1, in Examples 1 to 3, high quality images could be obtained without causing uneven gloss even after the abrasion durability test. This is considered to be because, by having the features described in the present invention as compared with Comparative Example 1, the surface layer is provided with low frictional properties, is less likely to be worn, and can maintain the smoothness of the surface.

Further, as in Comparative Examples 2 and 3,
Even if the mechanical strength is increased, after the wear durability test,
It became clear that gloss unevenness was generated in the image. This is presumably because the frictional property was not improved, and the surface layer was worn and the blade was worn, resulting in uneven gloss. In addition, the results of Examples 1 to 3 are as follows:
It is considered that this is not due to the strength improvement but to the effect obtained by lowering the friction.

When the surface roughness was large as in Comparative Example 4, it was evident that the glossiness was low in the initial image, and that after the abrasion durability test, uneven gloss was produced. This is considered to be because the low abrasion cannot be maintained for a long period of time due to the gradual wear of the irregularities.

From the results of Comparative Examples 5 and 6, the hardness of dimethyl silicone rubber containing no spherical silica was 4%.
When spherical silica was added to the dimethyl silicone rubber and the hardness became 50 °, no improvement in friction due to the addition of spherical silica was obtained. This is because, when the hardness of the elastic body is relatively hard, the pressure difference in the stress distribution at the time of pressing, which is caused by adding the spherical body, becomes small, and the effect of reducing friction is not sufficiently exhibited. Conceivable.

In the performance evaluation of the rollers of Examples 1 to 3, no toner offset was confirmed in the fixed toner image.

[0066]

The toner fixing roller according to the present invention has a low friction surface layer and is suitable for fixing high quality images.
Also, by using dimethyl silicone rubber as the elastic material forming the surface layer, a toner fixing roller having a low friction surface layer having particularly excellent toner release properties is provided, and further using spherical silica as a spherical body. Thereby, in addition to the toner releasability, a low friction property is uniformly imparted to the surface layer. Furthermore, the fixing device of the present invention can form a high-quality toner image and has excellent durability of the fixing roller.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a configuration of a heating and pressing fixing device used in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 1a Roller core metal 1b Elastic layer 1c Oil barrier layer 1d Surface layer 2 Pressure roller 3 Heater 4 Oil application roller 5, 6 Elastic blade

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaaki Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hideo Kawamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Non-corp. GA66 HA04 HA12 HA53

Claims (4)

[Claims] 1. A roller for use in a heat and pressure fixing device of a toner image forming apparatus for fixing toner, wherein a surface layer of the roller is an elastic body containing silicone rubber and / or fluorine rubber. The elastic body contains a sphere having higher hardness than the elastic body, and the sphere has a size of 0.5 to 2
The elastic body contains 1 to 50 parts by weight of the spherical body per 100 parts by weight of the elastic body.
A roller for a heat and pressure fixing device, wherein the SA hardness is less than 40 ° and the surface has a 10-point average roughness (Rz) of 1.0 μm or less in the surface layer. 2. The roller according to claim 1, wherein said silicone rubber is dimethyl silicone rubber. 3. The roller according to claim 2, wherein the spherical body is spherical silica. 4. A fixing device for use in a toner image forming apparatus, comprising a heating and pressing fixing roller according to claim 1.