JP2002082550A - Fixing belt for electromagnetic induction heating and transfer fixing belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing belt for electromagnetic induction heating and a transfer fixing belt performing efficient and uniform thermal fixing, having practical mechanical strength and produced at low cost in a small number of processes, and an image forming device using the belt. SOLUTION: In the fixing belt for electromagnetic induction heating or the transfer fixing belt equipped with a heating layer 1 consisting of heat resistant resin incorporating at least conductive particles and a surface mold-released layer 4 provided on its surface, the heating layer 1 has a heating part 2 constituted by unevenly distributing the conductive particles in the vicinity of an outer surface, and the thickness of the heating part 2 is <=50 μm and the density thereof is 0.5 times or more and less than 1.0 time as high as that of the conductive particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing belt for electromagnetic induction heating which heats and fixes a toner image using electromagnetic induction heating in an electrophotographic copying machine, a laser beam printer, a facsimile or the like, and an image using the same. The present invention relates to a forming apparatus. Also, the present invention relates to a transfer fixing belt that performs a transfer step and a fixing step using electromagnetic induction heat on one belt in the same image forming apparatus, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, as a method of fixing an image on a recording material in an electrophotographic image forming apparatus, a fixing method such as a heat roller method or a film heating method has been known. In these fixing systems, heat generated from a halogen lamp or a linear ceramic heater is applied to an unfixed toner image via a roller or a film to heat and fix the image.

[0003] On the other hand, in order to increase the efficiency of energy consumption, shorten the standby time, and require a quick start for an electrophotographic copying machine or the like, an eddy current is generated in a film having a heating layer to directly generate heat. An induction heating type fixing device and a fixing belt used for the fixing device have been proposed. Further, a transfer fixing device is known in which after a toner image formed on a photoreceptor is primarily transferred on one belt, the toner image is fused on the belt by electromagnetic induction heat and pressed against a recording material to fix the toner image. ing.

For example, in Japanese Patent Application Laid-Open No. 7-295411, a low heat conductive resin layer is provided on one surface of a cylindrical metal film.
On the other side, there has been proposed an image heating film in which a resin layer having a toner releasing property is formed by dipping or spray coating. However, in the case of using a metal film, the cost is high, such as an increase in the number of production steps, and the film thickness tends to be non-uniform due to dipping or spray coating, and therefore, there has been a problem in uniform fixing property and transportability. . In addition, a problem caused by too high rigidity of the metal film has been pointed out.

A fixing film in which a heat-generating layer is formed on the outer surface of a heat-resistant resin substrate by plating is also known (JP-A-7-114276, etc.). There is a problem of impurities and the like.

Therefore, there has been proposed a fixing belt for electromagnetic induction heating in which a heating layer is formed by dispersing metal particles or the like in resin or rubber. For example, Japanese Patent Application Laid-Open No. 9-146392 proposes a toner fixing film in which a base layer is formed of a low-rigid resin material and a heat-generating layer is formed of a low-rigid resin material containing at least a magnetic substance.

[0007]

However, in the fixing film described in the above publication, since the magnetic material is dispersed evenly in the heat generating layer, the weight of the resin is required to obtain the conductivity required for electromagnetic induction. However, it is necessary to add as much as 50 to 300% of a magnetic substance, which causes a problem that the intrinsic properties of the resin such as mechanical strength are reduced. In addition, when the heat generating layer is applied and formed, it is difficult to form a uniform thin heat generating layer, for example, the viscosity of the coating liquid increases due to a large content of the magnetic substance, and the heat generating layer can generate heat uniformly and efficiently. Was difficult to form. Furthermore, since it is necessary to form a base layer having sufficient strength separately from the heat generating layer, there is a problem that the number of manufacturing steps is increased.

In the case of a full-color fixing device in which three or more kinds of toners are superposed, melted, mixed and fixed, an elastic layer having elasticity is indispensable. In particular, uniform and efficient heat generation is required. This point is after the toner is overlaid and transferred,
The same applies to a full-color transfer / fixing device for transferring and fixing by fusing and mixing colors.

[0009] Therefore, an object of the present invention is to solve the above-mentioned problems by performing efficient and uniform heating and fixing.
Another object of the present invention is to provide a fixing belt for electromagnetic induction heating which has practical mechanical strength and can be manufactured at a low cost with a small number of steps, and an image forming apparatus using the same. Also,
It is an object of the present invention to provide a transfer fixing belt having the same function and effect, and an image forming apparatus using the same.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies on the forming method, structure, physical properties, and the like of a fixing belt used for electromagnetic induction heating. By properly controlling various conditions when forming a layer, it is possible to form a heat-generating portion (uniformly distributed layer of conductive particles) having a uniform density and thickness that can be adjusted, and the heat-generating portion can suitably generate electromagnetic induction heat. This led to the completion of the present invention.

That is, a fixing belt for electromagnetic induction heating according to the present invention comprises a heating layer made of a heat-resistant resin containing at least conductive particles, and a surface release layer provided on the surface. In the heat generating layer has a heat generating portion in which the conductive particles are unevenly distributed near the outer surface,
The thickness of the heat generating portion is 50 μm or less, and the density thereof is 0.5 times or more and less than 1.0 times of the conductive particles. Here, the thickness of the heat generating portion is
It is a value measured using a portion where the distance between the conductive particles unevenly distributed is 5 μm or more as a boundary line. Further, the density of the heat generating portion is a value obtained by calculating from the occupancy and the density of the area of the conductive particles in the thickness cross section of the heat generating portion.

In the above, the heat generating layer is formed by rotary centrifugal molding, and the density of the heat generating portion is 5 ×.
It is preferably at least 10 ⁻³ g / L.

The conductive particles may be made of at least one of ferromagnetic materials selected from the group consisting of nickel, iron, cobalt and alloys containing them, and the thickness of the heat generating portion may be 1 to 50 μm. preferable.

Alternatively, it is preferable that the conductive particles are made of at least one non-magnetic material selected from the group consisting of copper and an alloy containing copper, and the thickness of the heat generating portion is 20 μm or less.

On the other hand, an image forming apparatus according to the present invention provides a fixing belt for electromagnetic induction heating according to any one of the above, an exciting coil for generating an eddy current in the belt, and an electric current applied to the exciting coil. And a fixing device provided with a power source.

On the other hand, a transfer fixing belt according to the present invention is a transfer fixing belt for fixing a transfer image once transferred to itself to a recording material by utilizing electromagnetic induction heating. It is characterized by comprising a belt.

Further, another image forming apparatus of the present invention includes the above-mentioned transfer fixing belt, an exciting coil for generating an eddy current in the belt, and a power supply for applying a current to the exciting coil. And a transfer fixing device.

[Effects] According to the fixing belt of the present invention, as shown in the results of the examples, the heat generating portion in which the conductive particles are unevenly distributed near the outer surface of the heat generating layer is formed with a uniform and appropriate thickness. , And can be formed with an appropriate density, so that electromagnetic induction heating can be performed efficiently and uniformly. Therefore, heat can be efficiently and uniformly applied to the unfixed toner image, and since the standby state can be quickly heated to the fixing temperature, a high-precision image can be obtained with low power consumption. In addition, a portion where the conductive particles are not unevenly distributed can exhibit practical mechanical strength, and since both structural portions can be formed at the same time, a belt can be manufactured with a small number of steps and at low cost.

When the heat generating layer is formed by rotary centrifugal molding, and the density of the heat generating portion is 5 × 10 ⁻³ g / L or more, conductive particles having a density advantageous for rotary centrifugal molding are suitable. Since the heat-generating portion is formed with a high packing density, the conductivity required for electromagnetic induction heating is easily obtained, and the production becomes easier.

When the conductive particles are made of at least one of the above-mentioned ferromagnetic materials and the thickness of the heat-generating portion is 1 to 50 μm, the heat-generating portion made of the ferromagnetic material has a sufficient thickness for electromagnetic induction heat generation. And the flexibility of the belt can be sufficiently maintained.

Further, when the conductive particles are made of one or more of the above-mentioned non-magnetic materials and the thickness of the heat-generating portion is 20 μm or less, the heat-generating portion made of the non-magnetic material is advantageous for generating electromagnetic induction heat. It becomes very thin.

On the other hand, since the image forming apparatus of the present invention includes the fixing device provided with any of the above-described fixing belts for electromagnetic induction heating, it has practical mechanical strength and requires a small number of processes. Therefore, the fixing belt which can be manufactured at low cost can efficiently and uniformly generate electromagnetic induction heat. Therefore, heat can be efficiently and uniformly applied to the unfixed toner image, and since the standby state can be quickly heated to the fixing temperature, a high-precision image can be obtained with low power consumption.

On the other hand, in the transfer fixing belt of the present invention, the transfer fixing belt for fixing a transfer image once transferred to itself to a recording material by utilizing electromagnetic induction heating is the fixing device for electromagnetic induction heating described in any of the above. Since the belt is used, heat and fixing can be performed efficiently and uniformly by the above-described operation and effect, and the belt has practical mechanical strength, and can be manufactured with a small number of steps and at low cost.

Further, according to another image forming apparatus of the present invention, since the image forming apparatus includes the transfer fixing device provided with the above-described transfer fixing belt, the image forming apparatus has practical mechanical strength, has a small number of steps, and is low in cost. The electromagnetic induction heat can be efficiently and uniformly generated by the transfer / fixing belt that can be manufactured by the method described above. Therefore, heat can be efficiently and uniformly applied to the transferred image, and the image can be quickly heated from the standby state to the fixing temperature, so that an image with low power consumption and high accuracy can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail in the order of a fixing belt for electromagnetic induction heating, a transfer fixing belt, and an image forming apparatus.

(Fixing Belt for Electromagnetic Induction Heating) The fixing belt for electromagnetic induction heating of the present invention has a structure having at least a heat generation layer and a surface release layer, and the surface release layer is directly on the surface of the heat generation layer. Alternatively, it is provided via an elastic layer or the like. The heat generating layer is made of a heat-resistant resin containing at least conductive particles, and has a heat generating portion (a conductive particle uneven distribution layer) in which the conductive particles are unevenly distributed near the outer surface.

Such a heat generating layer is obtained by applying a raw material liquid of the above-mentioned material to the inner surface of a cylindrical mold and subjecting the conductive liquid to substantially centrifugal dispersion by a method such as rotational centrifugal molding. It can be suitably formed.

In the present invention, when actually used as a fixing belt, the recording material is brought into contact with the outer surface of the fixing belt to heat and fix the fixing belt. It is preferable because heat is transmitted to the material. Therefore, it is essential that the density of the conductive particles is higher than that of the heat-resistant resin, and the larger the difference, the lower the rotation speed during rotational centrifugal molding and the shorter the rotation time. Is preferred. Thereby, the conductive particles can be unevenly distributed in the vicinity of the outer surface in the heat generating layer, and the thickness of the heat generating portion can be reduced to 50 μm or less. If the thickness of the heat-generating portion exceeds 50 μm, the flexibility of the entire heat-generating layer becomes insufficient, so that it is difficult to obtain practical mechanical strength, and it is sometimes difficult to efficiently perform electromagnetic induction heat generation.

In the present invention, the density of the heat generating portion is added to the conductivity.
0.5 times or more and less than 1.0 times the conductive particles,
The conductivity required for conducting heat can be expressed and the surface strength
Etc. can be in a practical range. From this perspective
The density of the heat generating part is 0.6 times or more and 1.0 times or less of the conductive particles.
Preferably it is full. Rotational centrifugal molding as above
When using conductive particles having a preferable density,
Heat density is 5 × 10 ^-3g / L or more and the density is 6 ×
10^-3g / L or more is more preferable.

FIG. 1 shows an example of the fixing belt of the present invention.
The belt includes a heat generating layer 1 having a heat generating portion 2, an elastic layer 3, and a surface release layer 4. As the heat resistant resin of the heat generating layer 1, polyimide, polyamide imide, polyether ether ketone, polyphenylene sulfide, polybenzimidazole and the like can be used. Is preferred. In this case, by adjusting the type, molar ratio, and the like of the carboxylic dianhydride and diamine used, a fixing belt having appropriate rigidity or flexibility can be obtained.

The heat generating layer 1 further includes abrasion resistance,
In order to obtain a function such as slidability, a fluorocarbon resin particle or a functional filler such as a metal oxide may be filled to impart semiconductivity within the scope of the present invention.
When an organic filler such as fluororesin particles is added, since the density is close to that of the heat-resistant resin, it is difficult to inhibit the conductive particles from being unevenly distributed near the outer surface during rotational centrifugal molding. Further, even when an inorganic filler is added, it is preferable that the density is lower than that of the conductive particles.

The conductive particles of the heat generating layer are conductive particles that generate an eddy current in the heat generating portion by at least the magnetic field generated by the exciting coil, and are made of nickel, iron, cobalt, and alloys containing these. A magnetic material or a non-magnetic material such as aluminum, copper, titanium, and an alloy containing them can be used. When the heat generating layer in the present invention is formed by rotary centrifugal molding, the conductive particles need to have a higher density than a solution or precursor solution in which a heat-resistant resin material is dissolved. On the other hand, if the difference in density is small, a desired gradient dispersion cannot be obtained unless a high rotation speed is applied during rotary centrifugal molding. Therefore, the density of the conductive particles is preferably 5 × 10 ⁻³ g / L or more, and 6 × 10 ⁻³ g / L or more.
10 ^-3 g / L or more is more preferable.

The particle size of the conductive particles is preferably 10 μm or less, more preferably 5 μm or less, and most preferably 3 μm or less. If the particle size is too large, the conductive particles may have insufficient contact, approach, etc. when formed into a belt shape after molding, so that an appropriate resistance value for electromagnetic induction heating may not be obtained. The particle size here refers to the average particle size. Further, the particle size distribution may be adjusted to obtain a desired resistance value so that a dense packing structure (for example, a structure in which small-sized particles are filled in gaps between large-sized particles) may be obtained.

Depending on the amount of the conductive particles added,
The thickness of the heat-generating portion after molding can be controlled, but the preferable thickness of the heat-generating portion varies depending on the properties of the conductive particles. For this reason, the preferable thickness of the entire heat generating layer also differs. For example, when a ferromagnetic material is used for the conductive particles, the following thickness is preferable for the thickness of the entire heat generating layer of 50 to 200 μm, and when a nonmagnetic material is used, the thickness is 20 to 200 μm.
The following thickness is preferable for 150 μm.

That is, the amount of heat generated by the electromagnetic induction heat generation depends on the thickness of the heat generating portion. The depth σ at which the magnetism generated from the coil permeates is affected by the frequency f of the current applied to the heating coil, the specific resistance ρ of the substance, and the specific magnetic permeability μτ, and is expressed by the following equation.

Σ = ρ ^1/2 / (π · f · μ ₀ · μτ) where μ ₀ represents the magnetic permeability in a vacuum. If the thickness is less than the penetration depth, the magnetism generated from the coil leaks, making it difficult to obtain sufficient heat generation. If the thickness is too large, the flexibility of the belt is reduced due to the rigidity of the metal, so that the transportability and the paper separating property as a fixing belt tend to be inferior. Therefore, when a ferromagnetic material is used as the conductive particles, the thickness of the heat generating portion is preferably 1 to 50 μm. On the other hand, when a non-magnetic material is used, since the calorific value increases as the thickness decreases, the thickness of the heat generating portion after molding is preferably 20 μm or less, more preferably 10 μm or less.

After satisfying the density according to the present invention,
In order to set the thickness of the heat generating portion to the above value, material conditions such as the amount added to the heat-resistant polymer material serving as the base material, viscosity, manufacturing conditions thereof, and rotational centrifugal molding conditions are closely involved.

For the elastic layer, a heat-resistant elastomer such as silicone rubber or fluorine rubber which can withstand use at the fixing temperature can be used. Various fillers may be mixed into the elastic layer for the purpose of thermal conductivity, reinforcement, and the like. Examples of the thermally conductive particles include diamond, silver, copper, aluminum, marble, and glass, but practically silica, alumina,
Examples include magnesium oxide, boron nitride, and beryllium oxide.

The thickness of the elastic layer is preferably from 10 to 500 μm, more preferably from 50 to 400 μm. If the thickness is less than 10 μm, it is difficult to obtain the desired elasticity in the thickness direction. On the other hand, if the thickness exceeds 500 μm, the heat generated in the heating layer hardly reaches the outer peripheral surface of the fixing film, and the thermal efficiency tends to deteriorate. There is.

The surface release layer is not only capable of withstanding use at the fixing temperature but also has toner release properties. For example, silicone rubber, fluorine rubber, PFA, PTFE, FEP
And the like are preferably used. The thickness of the release layer is preferably from 5 to 100 μm, more preferably from 10 to 50 μm. In addition, an adhesive treatment with a primer or the like may be performed to improve the interlayer adhesive strength.

The heat-generating layer of the fixing belt for electromagnetic induction heating shown in FIG. 1 can be obtained by subjecting a polyamic acid solution containing the above-mentioned conductive particles to a raw material liquid and performing centrifugal molding and imide conversion. The polyamic acid solution can be obtained by polymerizing a carboxylic dianhydride and a diamine in a solvent as described above. From the viewpoint of mechanical strength and the like, the carboxylic dianhydride is preferably an aromatic carboxylic dianhydride, and more preferably an aromatic tetracarboxylic dianhydride. Specific examples of such aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′,
4,4′-benzophenonetetracarboxylic dianhydride,
3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride , 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like. On the other hand, examples of diamines include 4,4′-diaminodiphenyl ether,
4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, m
-Phenylenediamine, p-phenylenediamine, benzidine, 3,3'-dimethylbenzidine and the like.

As a solvent for the polymerization reaction of the carboxylic dianhydride and the diamine, any suitable solvent can be used.
A polar solvent is preferably used from the viewpoint of solubility and the like. As such a polar solvent, N, N-dialkylamides are useful, and examples thereof include low molecular weight N, N-dimethylformamide, N, N-dimethylacetamide and the like, which are obtained by evaporation, substitution or diffusion. It can be easily removed from polyamic acid and polyamic acid molded products. Other organic polar solvents include N, N-diethylformamide, N, N-diethylacetamide, N, N
-Dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2
-Pyrrolidone, pyridine, dimethylsulfoxide and the like, which may be used alone or in combination. Further, phenols such as cresol and phenol, benzonitrile, xylene, cyclohexane, hexane, benzene, toluene and the like can be used alone or in combination with the organic polar solvent. In addition, since the polyamic acid is hydrolyzed to lower the molecular weight, the polymerization of the polyamic acid is preferably carried out under substantially anhydrous conditions.

A polyamic acid is obtained by reacting the carboxylic dianhydride (a) with the diamine (b) in an organic polar solvent. At this time, the monomer concentration (the concentration of (a) + (b) in the solvent) is set according to various conditions, but is preferably 5 to 30% by weight. Further, the reaction temperature is preferably set to 80 ° C or lower, particularly preferably 5 to 50 ° C.

As described above, the polyamic acid is formed by reacting the carboxylic dianhydride with the diamine in the organic polar solvent, and the solution viscosity increases as the reaction proceeds. In the present invention, in order to obtain a belt having a desired inclined dispersion during rotational centrifugal molding when the polyamic acid solution has a high viscosity, a high rotational speed must be given for a long time,
It is necessary to use a polyamic acid solution having a somewhat low viscosity from the viewpoint of production cost and energy saving. In consideration of this point, a polyamic acid solution having an appropriate viscosity can be used in view of desired thickness accuracy and workability. Specifically, the viscosity (25 ° C.) of the polyamic acid solution containing the conductive particles in a B-type viscometer is preferably 0.1 10,000 poise, and more preferably 1 to 8000 poise.

The heat generating layer in FIG. 1 is manufactured by using a rotary centrifugal molding. That is, the polyamic acid solution is applied to the inner surface of a cylindrical mold, and the thickness of the heat generating layer is made constant by rotating and centrifuging the mold. At this time, it is necessary to remove a solvent or the like by applying a certain amount of heat at least until the tubular body as the heat generating layer can support itself. Regarding the application, in order to more easily obtain a heat generating layer having a heat generating portion of a desired density, after applying a polyamic acid solution containing conductive particles of high concentration in advance, do not contain low concentration or conductive particles When the polyamic acid solution is applied and subjected to rotary centrifugal molding, a heat generating layer tubular body having a desired effect can be easily obtained. After the heat generating layer tubular body can support itself, heating at 300 ° C. or more is performed to complete the imide conversion reaction, remove ring-closing water, remove the solvent, and the like.

The elastic layer and the surface release layer are subjected to an adhesive treatment such as a primer on the heat generating layer, if desired, and each layer is formed thereon by a known method such as spray coating or dispenser coating. Remove and cure reaction.

(Transfer-fixing belt) The transfer-fixing belt of the present invention is a transfer-fixing belt for fixing a transfer image once transferred to itself to a recording material using electromagnetic induction heating. It has the same configuration as the fixing belt. In other words, although a normal fixing belt may not be used as a transfer fixing belt as it is in terms of its conductivity and the like, the fixing belt for electromagnetic induction heating of the present invention may be used as a transfer fixing belt without particularly changing the configuration. It can be suitably used.

(Image Forming Apparatus) On the other hand, an image forming apparatus according to the present invention includes the fixing belt for electromagnetic induction heating described above, an exciting coil for generating an eddy current in the belt, and an exciting coil. The fixing device includes a power supply for applying a current. The image forming apparatus of the present invention is characterized in that the fixing belt of the present invention is used in place of the conventionally known fixing belt for electromagnetic induction heating. Any power supply can be used. For example,
JP-A-9-146392, JP-A-7-29541
No. 1, Japanese Patent Application Laid-Open No. 7-114276, etc., the fixing device, the image forming apparatus, or each unit constituting the same can be similarly applied.

Further, another image forming apparatus of the present invention includes the above-described transfer / fixing belt, an exciting coil for generating an eddy current on the belt, and a power supply for applying a current to the exciting coil. And a transfer fixing device. Since such an image forming apparatus is characterized in that the transfer fixing belt of the present invention is used in place of the conventionally known transfer fixing belt utilizing electromagnetic induction heating, the other parts are
Any of an excitation coil, an application power supply, and the like in the same type of image forming apparatus can be adopted. For example, JP-A-11-3528
The transfer fixing device, the image forming device, and the respective units constituting the same, which are adopted in JP-A No. 04, JP-A-2000-268952, etc., can be similarly applied.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

Example 1 Approximately equimolar amounts of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine were added to N-methyl-2-pyrrolidone (NMP) (solid (20% concentration) and dissolved in a nitrogen atmosphere at room temperature with stirring to obtain a 1500 poise polyamic acid solution. A copper powder having an average particle size of 2 μm (density of 8.9 × 10 ⁻³ g / L) was mixed with the polyamic acid solution so as to be 7% by volume with respect to the solid content of the polyimide.
Dispersed. Next, a cylindrical mold (inner diameter 90 mm, length 50
(0 mm) on the inner surface with a dispenser to apply a 400 μm-thick polyamic acid solution, and then rotated at 1500 rpm for 10 minutes to obtain a uniform applied surface. Next, while rotating at 3000 rpm, 60 ° C. hot air is blown from the outside of the mold for 60 minutes, and then heated at 150 ° C. for 50 minutes, and then 300 ° C.
Temperature at a rate of 3 ° C./min.
The mixture was heated for 1 minute to remove the solvent, remove the dehydrated ring-closing water, and perform the imide conversion reaction. Thereafter, the temperature was returned to room temperature, and the resultant was peeled from the mold to obtain a seamless belt having a total thickness of 74 to 78 μm. When a cross-sectional SEM observation of this belt was performed, a heating portion having a uniform thickness of 6 to 7 μm was formed in a state where copper powder was unevenly distributed on the outer surface of the belt. This belt is arranged so as to face the exciting coil, and a current (for example, a frequency of 10
(0 kHz), the heating layer generated heat.

Example 2 The copper powder used in Example 1 was replaced with nickel powder (average particle size 1.8 μm, density 8.9 × 10 ⁻³ g).
/ L), and a belt was produced in the same manner except that the volume was 28% by volume with respect to the solid content of the polyimide, to obtain a seamless belt of 73 to 78 μm. When a cross-sectional SEM observation of this belt was performed, a heating portion having a uniform thickness of about 20 μm was formed in a state where the nickel powder was unevenly distributed on the outer surface of the belt. When the belt was arranged so as to face the exciting coil and a current was applied to the coil, the heat generating layer generated heat.

[Example 3] A polyamic acid solution containing copper powder (3000 poise) prepared in the same manner as in Example 1 was applied to the inner surface of a cylindrical mold, and was then dropped by its own weight using a bullet-shaped traveling body. Obtained a uniform coating surface of 400 μm. Next, while rotating the mold at 2500 rpm, 60
℃ hot air for 60 minutes, then heated at 150 ℃ for 50 minutes, then heated up to 300 ℃ at a rate of 3 ℃ / min,
The mixture was further heated at 300 ° C. for 20 minutes to remove the solvent, remove the dehydrated ring-closing water, and perform the imide conversion reaction, and then returned to room temperature and peeled off the mold to obtain a seamless belt having a total thickness of 73 to 77 μm. . When a cross-sectional SEM observation of this belt was performed, it was found that copper powder was unevenly distributed on the outer surface of the belt,
A heat generating portion having a uniform thickness of 7 μm was formed. When the belt was arranged so as to face the exciting coil and a current was applied to the coil, the heat generating layer generated heat.

Example 4 Carbon black in NMP
(23% by weight with respect to the solid content of the polyimide resin).
The mixture was uniformly dispersed by stirring with a mill for 8 hours. This car
3,3 ', 4,4'-biphenyl in bon black dispersion
Of tetracarboxylic dianhydride and p-phenylenediamine
Dissolve approximately equimolar (solids concentration 20%), and in nitrogen atmosphere
At room temperature with stirring at 1500 pores
To obtain a carbon black-dispersed polyamic acid solution. This
Copper powder having an average particle size of 2 μm (density
8.9 × 10^-3g / L) with respect to the polyimide solid content is 7
The mixture was mixed and dispersed so as to be a volume%. Then cylindrical mold
(Inner diameter 320mm, length 500mm)
Amidic acid solution is applied with a thickness of 400 μm using a dispenser.
Then, rotate at 1500 rpm for 10 minutes to obtain a uniform coating surface.
Obtained. Next, while rotating at 2500 rpm,
After blowing hot air at 60 ° C from the side for 60 minutes,
Heat for 0 minutes, then ramp up to 300 ° C at 3 ° C / min
And further heated at 300 ° C for 20 minutes to remove the solvent.
Thereafter, dehydration ring-closing water was removed, and an imide conversion reaction was performed.
Then return to room temperature, peel from the mold, total thickness 74-77μ
m was obtained. Section S of this belt
EM observation revealed that copper powder was unevenly distributed on the outer surface of the belt
In this state, a heating section having a uniform thickness of 6 to 7 μm is formed,
Other base layers have carbon black evenly dispersed
Was. The surface resistivity of the inner surface of this belt is 1.5 × 10
¹¹Ω / □, and transfer the toner image on the photoreceptor
It can be confirmed that the transcription function for transcription can be expressed
Was. This belt is placed facing the excitation coil,
When a current was applied to the heating layer, the heating layer generated heat. The surface resistivity
Is measured by Hiresta UP MCP-HTP16 (Mitsubishi Chemical
Probe: UR-100), applied voltage 100
V, 10 seconds later, surface resistance at 25 ° C and 60% RH under measurement conditions.
The resistance was measured.

Comparative Example A seamless belt having a total thickness of 72 to 78 μm was obtained in the same manner as in Example 3 except that the mold was not rotated after the bullet-shaped traveling body was dropped by its own weight. Was. When a cross-sectional SEM observation of this belt was performed, copper powder was uniformly dispersed throughout the cross-section. This belt was arranged so as to face the exciting coil, and the heating layer did not generate heat even when the current of the coil was passed.

Table 1 shows the above results.

[0057]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a fixing belt for electromagnetic induction heating according to the present invention.

[Explanation of Signs] 1 Heating layer 2 Heating portion (distributed layer of conductive particles) 3 Elastic layer 4 Surface release layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Masakazu Sugimoto 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Keizo Mizobe 1-1-2 Shimohozumi, Ibaraki-shi, Osaka F-term in Nitto Denko Corporation (reference) 2H033 BA11 BA12 BE06 BE09 3K059 AB19 CD44 CD62 CD63

Claims (7)

[Claims] 1. A fixing belt for electromagnetic induction heating comprising: a heat generating layer made of a heat-resistant resin containing at least conductive particles; and a surface release layer provided on a surface of the fixing belt, wherein the heat generating layer includes the conductive particles. Has a heating part unevenly distributed near the outer surface, the thickness of the heating part is 50 μm or less, and the density is 0.5 times or more and less than 1.0 times of the conductive particles. Fixing belt for electromagnetic induction heating. 2. The heating layer is formed by rotary centrifugal molding, and the density of the heating section is 5 × 10 ⁻³ g / L.
The fixing belt for electromagnetic induction heating according to claim 1, wherein: 3. The conductive particles are made of at least one of ferromagnetic materials selected from the group consisting of nickel, iron, cobalt and alloys containing these, and the thickness of the heat generating portion is 1 to 3.
The fixing belt for electromagnetic induction heating according to claim 1, wherein the fixing belt has a thickness of 50 μm. 4. The heat generating portion according to claim 1, wherein the conductive particles are made of one or more nonmagnetic materials selected from the group consisting of copper and an alloy containing copper, and the thickness of the heat generating portion is 20 μm or less. Fixing belt for electromagnetic induction heating. 5. The fixing belt for electromagnetic induction heating according to claim 1, an exciting coil for generating an eddy current in the belt, and a power supply for applying a current to the exciting coil. Image forming apparatus provided with a fixing device provided with the fixing device. 6. A transfer fixing belt for fixing a transfer image once transferred to itself to a recording material by utilizing electromagnetic induction heating, comprising the fixing belt for electromagnetic induction heating according to any one of claims 1 to 4. A transfer fixing belt characterized by the following. 7. A transfer fixing device comprising: the transfer fixing belt according to claim 6; an exciting coil for generating an eddy current in the belt; and a power supply for applying a current to the exciting coil. Image forming device.