JPH117213A - Fixing roller and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently utilize heat energy emitted from a phase transition heat generating material by making its density gradient increase as it goes toward the outside surface in the circumferential direction of a phase transition heat generating layer. SOLUTION: A fixing roller 1 is provided with a hollow cylindrical core metal 2. On the outer periphery of the core metal 2, the phase transition heat generating layer 5 having fine grains 3 as the phase transition heat generating material dispersed in a binder 4 such as polyimide is formed. The fine grains 3 as the phase transition heat generating material in the phase transition heat generating layer 5 are higher in density as it goes toward the outside surface and relatively, the concn. of the binder 4 is lower as it goes to the outside surface. The side of the core metal 2 is firmly fixed by the binder 4. A protective layer 6 is formed on the outer periphery of the phase transition heat generating layer 5. This layer 5 is covered and sealed by the protective layer 6, so that it prevents the fine grains 3 as the phase transition heat generating material from flowing out, when the fine grains 3 are in melted states.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing roller used in a fixing device such as a copying machine, a printer, a facsimile, and the like, and a method of manufacturing the fixing roller.

[0002]

2. Description of the Related Art Generally, in an electrophotographic copying machine, a printer, a facsimile, etc., fixing of a developed image
A fixing device including a fixing roller and a pressure roller is used. In this fixing device, printing paper on which toner has been transferred and developed is inserted between rollers between the fixing roller and the pressure roller. As a result, the toner that forms the image is heated and melted (softened), and is fused and fixed on the printing paper.

As a fixing roller of this type, the applicant of the present invention has provided a phase-change heating layer on the outer periphery of a hollow cylindrical core with a phase-change heating material capable of phase transition between amorphous and crystalline. There has been proposed a fixing roller having a configuration in which the phase change heat generating layer is covered with a protective layer (for example, see Japanese Patent Application Laid-Open No. Hei 7-140823). According to this fixing roller, the temperature of the outer peripheral surface of the fixing roller reaches a temperature (predetermined temperature) required for fixing by using a temperature rise by heating from the main heat source.
In the phase transition heating layer, heat energy (crystallization energy) is generated by the phase transition from amorphous to crystalline. Thereby, the temperature rise of the outer peripheral surface of the fixing roller is promoted more than the temperature rise of only the main heat source. The use of this fixing roller is expected to reduce the warm-up time and save power.

[0004]

These phase-change heat-generating layers are formed by dispersing a high-conductivity substance in order to increase the thermal conductivity, or a plurality of layers having different heat-generating temperatures in order to smooth the heat generation. It is conceivable to use a mixture of phase change exothermic materials.

However, in such a fixing device, since the phase-change exothermic material is used after being melted, these phase-change exothermic materials are coated and dispersed with a binder so that they do not aggregate with each other due to the melting, and the phase-change exothermic material is dispersed. It is desirable that the heat generating materials be isolated from each other.

Accordingly, the present applicant has already proposed a method for preventing fluidization by coating fine particles of a phase-change exothermic material by using a precursor before imidization as a binder (Japanese Patent Application No. 9-222,197).
-88062). According to this method, the fine particles of the phase change exothermic material are bound by dispersing the fine particles of the phase change exothermic material in the polyimide precursor to form a layer, and then heating the layer to imidize the polyimide precursor. A phase change heating layer dispersed in the agent is obtained.

[0007] By the way, the phase-change exothermic material basically has only a constant calorific value equivalent to the latent heat of fusion even when it is completely amorphous. Therefore, when the phase-change exothermic material is used by dispersing it in a binder, the amount of heat generated in a certain volume is reduced, so that there is a problem that the temperature cannot be increased efficiently.

The present invention has been made in view of the above circumstances, and can promote heating by utilizing thermal energy generated at the time of phase transition, and the cycle of melting and crystallization of the phase transition exothermic material is repeated. It is an object of the present invention to provide a fixing roller which can efficiently utilize heat energy generated from the phase change heat generating material in a fixing roller in which aggregation of the phase change heat generating material does not occur, and a method of manufacturing the same.

[0009]

In order to achieve the above object, an object of the present invention is to provide a phase change heat generating material in which a phase change heat generating material which generates heat energy at the time of phase change is dispersed in a binder. In the fixing roller having a layer, the phase-change exothermic material is characterized in that a density gradient is increased toward an outer circumferential surface of the phase-change exothermic layer.

With this configuration, the density of the phase transition heat generating material on the surface side of the fixing roller can be increased. When the fixing roller is heated by an internal heater or the like, the phase change heat generating material generates heat at a predetermined temperature. At this time, since the density of the heat generating material in the phase change heat generating layer is higher on the surface side, the calorific value is relatively higher on the surface side. Thereby, the surface of the fixing roller is efficiently heated.

The invention according to claim 2 is characterized in that the binder is polyimide.

According to this structure, since the polyimide is chemically and thermally stable, the binder can maintain its shape even if the melting and crystallization cycle is used repeatedly, and the polyimide can be used as a phase-change exothermic material. No aggregation occurs.

The invention according to a third aspect is characterized in that the phase-change heating layer contains a good heat conductive substance.

With this configuration, the thermal conductivity of the phase change heat generating layer is improved, and the temperature rise of the fixing roller is further accelerated.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a fixing roller according to the first aspect, wherein a binder coating liquid in which a phase-change heat-generating material that generates thermal energy at the time of phase transition is dispersed is applied. A tubular coating application step of applying a hollow cylindrical shape to the substantially cylindrical temporary support inner surface, by rotating the temporary support at a high speed, to obtain a density gradient of the phase-change exothermic material in the cylindrical coating. Density gradient providing step of increasing the density toward the centrifugal force direction, a core metal insertion step of inserting a support core metal into the temporary support, a bonding step of bonding the coating film to the support core metal, from the temporary support. The step of taking out the core metal together with the phase transition heating layer is sequentially performed. .

Since the phase-change exothermic material has a higher specific gravity than the solution used as the binder, the film of the binder-coating liquid in which the phase-change exothermic material is dispersed is applied to the fluidity of the binder-coating liquid. By rotating at a high speed in a certain state, the phase change heating material can move toward the outer surface where the centrifugal force acts. Thereby, a cylindrical coating film in which the density gradient of the phase change exothermic material is increased toward the outer surface in the circumferential direction is obtained.

A fixing roller according to claim 1 is obtained by inserting a core metal serving as a support into the inside of the cylindrical coating film and joining the core metal and the cylindrical coating film and then removing the temporary support. .

A fifth aspect of the present invention is characterized in that, after the removing step of the fourth aspect of the present invention, a surface layer applying step of applying a surface layer to the outer surface of the phase change heat generating layer is performed. Thereby, the method for manufacturing a fixing roller according to claim 1 provided with the surface layer is provided.

According to a sixth aspect of the present invention, the bonding step is performed by heating. By heating, the binder shrinks and joins to the core, making it easier to remove the core together with the heat generating layer.

The invention according to claim 7 is characterized in that the temporary support has an inner surface coated with a fluororesin.

According to this structure, since the fluororesin has good releasability, the phase-change heating layer can be easily released from the temporary support even after the core metal and the phase-change heating layer are joined.

The invention according to claim 8 is characterized in that the temporary support is glass.

According to this structure, since the glass has good releasability, the phase transition heating layer can be easily released from the temporary support even after the core metal and the phase transition heating layer are joined. Further, glass is softened and deformed at a relatively low temperature as compared with metal and has good moldability, so that processing is easy.

According to a ninth aspect of the present invention, the binder coating liquid is a polyimide precursor coating liquid, and the polyimide coating is heated under reduced pressure at an arbitrary stage after the density gradient applying step. It is characterized by combining a curing step for curing the body.

With this structure, the polyimide has good chemical resistance and is difficult to dissolve in a solvent, but the polyimide precursor can be easily dissolved in the solvent to adjust the solution viscosity. The particles of the transition exothermic material can be uniformly dispersed. In addition, since this method is a wet coating method, it is easy to process the phase change heat generating layer into an arbitrary form.

According to a tenth aspect of the present invention, the surface layer is formed by opening at least one end, and the curing step is performed while removing moisture from the open end.

According to this structure, water generated during the curing reaction can be removed from the phase-change heating layer.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fixing roller according to the present invention will be described below with reference to the drawings.

The fixing roller of the present invention uses the temperature rise caused by heating from the main heat source to release the energy stored in the substance in the form of heat, so that the surface of the fixing roller becomes faster than the temperature rise of the main heat source alone. It applies the principle of raising the temperature, and is used as a fixing roller of a heat fixing device.

The fixing roller 1 has, for example, a hollow cylindrical cored bar 2 as shown in FIG. As the material of the metal core 2, for example, aluminum, its alloy, stainless steel, or the like is used. On the outer periphery of the cored bar 2 is formed a phase-change heating layer 5 in which fine particles 3 of a phase-change heating material are dispersed in a binder 4 such as polyimide. The fine particles 3 of the phase change heat generation material in the phase change heat generation layer 5 have a higher density toward the outer surface, and the concentration of the binder is relatively lower toward the outer surface. Is firmly fixed by the binder.

A protective layer 6 is formed on the outer periphery of the phase change heating layer 5. The protective layer 6 covers and seals the phase change heat generation layer 5 to prevent the particles 3 of the phase change heat generation material from flowing out in a molten state. This protective layer 6 may be a layer having releasability for preventing adhesion to toner and the like. An adhesive layer, a current-carrying layer, an insulating layer, and the like may be added to the fixing roller 1 as necessary.

The fixing roller 1 is provided with a main heat source for raising the temperature of the outer periphery of the fixing roller 1 to the toner fixing temperature Tt, and heating and melting the crystallized phase change heating layer 5. In this example, a main heat source (not shown) is provided in the hollow portion 7 inside the metal core 2. Examples of the main heat source include a heater such as a halogen lamp, an infrared lamp, and a nichrome wire.

The phase-change exothermic material used in the present invention is:
It is a material that generates heat with phase transition. Such materials are
In general, it is what becomes amorphous by quenching from a molten state, and crystallizes when the temperature of the material in the amorphous state is increased.
This is a substance having a so-called amorphous region.

These phase change exothermic materials generate heat during the phase transition from amorphous to crystalline. Since the crystallization temperature is a temperature specific to the substance, the crystallization start temperature and the crystallization end temperature are It depends on the phase-change exothermic material used. The crystallization temperature is a temperature at which an amorphous phase which is metastable in terms of energy is changed to a more stable crystal phase, and is between a melting point determined by a substance and a glass transition point. This melting point is an important property for re-amorphizing a substance once heated and reinitializing the substance. The melting point is higher than the fixing temperature at which the toner is softened and fused, and the temperature is as low as possible from the viewpoint of energy saving. Is desirable.

The phase-change exothermic material having such performance can be widely used from inorganic substances and organic substances.
In the case of an inorganic substance, for example, groups III to VI of the periodic table
A multi-group system having an amorphizable region is known. Among these, chalcogens and chalcogenide compounds containing Se (selenium) as a main component are suitable materials because they rapidly crystallize and generate heat, and also generate a large amount of heat during crystallization.

In the case of organic substances, for example, PET
(Polyethylene terephthalate), PBT (Polybutylene terephthalate), and other high molecular substances such as polyesters such as polyesters, and low molecular substances such as diphenyl isophthalate derivatives and bisphenol derivatives. Those which generate heat during crystallization and crystallization can be used.

On the other hand, examples of the binder for coating the particles of the phase-change exothermic material include a fluororesin, a polyimide resin, and an epoxy resin, but these resins are generally difficult to process. The polyimide precursor is exemplified as a material having good workability.

Many polyimides are usually produced by a special vapor deposition polymerization method, but when polymerized from an imide monomer, they are polymerized in a solvent and pass through an intermediate provided as a solution. This intermediate is called a polyimide precursor because it generates water by heating to complete the imidization reaction and produce polyimide. When the particles of the phase-change exothermic material are dispersed in the solution of the polyimide precursor and the imidization is completed while dehydrating by heating or the like, a polyimide film in which the phase-change exothermic material is firmly bonded is formed. Even if the phase-change exothermic material is melted to amorphize the internal phase-change exothermic material in a state where the particles are covered with the particles, the coating film is not melted or decomposed. By maintaining the shape, the initial particle shape can be maintained. This polyimide precursor can form a good dispersion film by utilizing this property.

Such a polyimide precursor is commercially available as a solution of a polyimide precursor such as a wholly aromatic polyamic acid or polyamic acid for use as a heat-resistant insulating varnish. A wholly aromatic polyimide varnish is preferably used because it has particularly excellent binding properties and heat resistance. Such a precursor can be diluted, so that it is easy to adjust the viscosity to be appropriate for dispersing a phase change exothermic material described later. Thereby, the particles of the phase-change exothermic material can be easily dispersed, and a dispersion coating liquid in which the phase-change exothermic material is uniformly dispersed can be obtained. As these solvents, N-methyl-2-pyrrolidone, dimethylacetamide, aromatic hydrocarbons and the like are used.

Other additives may be further added to the phase change heat generating layer 5 if necessary. For example, by blending a material having good thermal conductivity (good thermal conductive material) such as carbon black, the heat transfer rate of the phase change heating layer is increased, and the surface temperature of the roller is increased to a desired temperature. it can.

Next, the manufacturing process of the fixing roller of the present invention will be described with reference to FIGS.

In FIG. 2, reference numeral 11 denotes a temporary support. The temporary support 11 has a cylindrical shape whose inner die φ11 is substantially the same as the outer diameter d1 of the fixing roller 1, and its length L11 is
Is longer than the length L2. The temporary support 11 is rotatable in the direction of a rotation arrow a by a rotation mechanism (not shown).

A dispenser 12 is disposed on one end 11a of the temporary support 11. The dispenser 12 is a coating apparatus for supplying a dispersion coating solution (solution) in which a phase-change heat-generating material is uniformly dispersed in a binder to a temporary support 11 and applying the same by a wet coating method such as spray coating. is there. Conventionally known coating devices can be used,
For example, in this example, a coating liquid supply tank and a metering pump are provided inside, and the metering pump is provided with a spray nozzle 12a.
It is connected to the. In addition, this dispenser 12
Scanning means for scanning the nozzle portion 12a at a constant speed in the direction of the cylindrical axis of the temporary support 11 (double arrow b) is built in. The nozzle portion 12a may be fixed as long as the temporary support 11 can be operated in the cylindrical axis direction.

Using this apparatus, the temporary support 11 is
Rotate at a low speed of about 100 rpm. Then, while the nozzle portion 12a is scanned by a desired length of the phase change heat generating layer 5, the dispenser 12 applies the binder coating liquid in which the particles 3 of the phase change heat generating material are dispersed in the binder 4 at a constant speed. Supply by Thus, the coating liquid layer can be spirally applied to the inner surface of the temporary support 11 by the length of the phase change heat generating layer 5 over the entire surface. In the density gradient applying step described below, the thickness of the coating liquid can be made uniform.
The coating liquid may have irregularities (tubular coating application step).

Next, this temporary support 11 is
When rotated at a high speed of more than rpm, the thickness of the coating liquid is made uniform by the action of centrifugal force, and the phase change exothermic material in the coating liquid moves outward because the specific gravity is larger than that of the binder. I do. The moving speed is appropriately determined by the rotation speed and the rotation time in consideration of the viscosity of the binder used and the specific gravity of the phase change heat generating material. The faster the rotation speed, the higher the density gradient of the phase change heating material toward the outer circumferential surface of the phase change heating layer (density gradient applying step). Since the binder is usually viscous, the applied density gradient is stable for a certain period of time, but if it is unstable, the viscosity can be reduced by applying a process such as partially removing the solvent in the binder. It can rise and be stable.

The other end 11b of the temporary support 11 has a core 2
Is moved from the inner surface to move the metal core 2 in the double-headed arrow c direction. The core metal moving means is for inserting and removing the metal core 2 into and from the temporary support 11. Since the thickness of the coating film is usually several mm or less, it is inserted while being fixed to a guide roller or the like while maintaining this accuracy (core metal insertion step). The core metal 2 may be provided with an arbitrary layer such as an insulating layer on the outer surface, or may be provided with a main heat source or the like.

In FIG. 2, a portion indicated by a two-dot chain line (imaginary line) 13 in which the temporary support 11 is disposed is a single hermetically sealable chamber 13 in which a temperature not shown is shown. An adjustable heater is arranged, and the entire interior of the chamber 13 is configured to be able to be depressurized by a vacuum pump or the like.

The joining is performed while heating or reducing the pressure in the chamber 13. By removing the solvent in the binder, adhesion is generated and the coating film is bonded to the core metal (core metal bonding step). Bonding in this step may be performed as long as the coating film has a necessary bonding property so that it can be taken out together with the cored bar 2, but may be in close contact. For example, when a polyimide precursor is used as a binder, the coating film shrinks when preheated at a temperature equal to or lower than the melting point of the phase-change exothermic material, for example, at a temperature of about 120 ° C. Joined to gold 2.

Next, the core metal 2 is taken out of the temporary support 11 together with the phase-change heating layer 6 (take-out step). When a surface layer 6 such as a protective layer is provided on the outer surface of the phase change heat generating material layer 5, the protective layer 6 is preferably provided in this step before curing (surface layer providing step). . Phase transition heating layer 6
Has a strength necessary for providing the protective layer 6 by the core metal bonding step, and can be applied by a usual method such as coating with a PFA tube. When the by-products are generated, it is necessary to keep the by-products generated in the curing step so that they can be removed. For example, one end is an open end.

Next, the core metal 2 provided with the protective layer 6 is heated while being reduced in pressure by a rotary pump or the like for curing. Thereby, the imidization reaction accompanied by the dehydration reaction is completed (curing step). Further, in this curing step, the phase-change heating layer 5 and the core metal 2 are adhered and fixed. The heating temperature in this step is equal to or higher than the melting point of the phase change exothermic material. However, since the protective layer 6 is provided, the phase change exothermic layer 5 is stable even when heated to a temperature equal to or higher than the melting point. Thereby, it is possible to obtain the phase change heat generating layer 5 without moisture remaining in the phase change heat generating layer 5 and without any bubbles inside. Further, if the open end is sealed while reducing the pressure inside, the fixing roller 1 having no bubbles inside can be obtained. Such a fixing roller 1 is less likely to deform due to the generation of air bubbles and the like due to heating during use during molding and use of the roller.

Further, the fixing roller 1 thus obtained can be rapidly cooled to make the phase change heat generating material 3 amorphous (amorphizing step). Thus, the fixing roller 1 can be used immediately.

Hereinafter, the present invention will be described more specifically with reference to examples.

(Example 1) Fine particles of high-purity Se (99.99%) produced by a hydrolytic reduction method were dispersed in a 30% diluent of a polyimide precursor (Trenice # 3000, manufactured by Toray Industries, Inc.) to obtain a coating liquid. . Using this coating solution, the inner diameter φ11 whose inner surface is coated with fluororesin by spray coating is 21 mm
It was applied on a cylindrical mold (temporary support 11) made of φ aluminum.

Then, the mold 11 is rotated at 1000 rpm to make the coating uniform, an aluminum core 2 having an outer diameter of 20 mm is inserted, heated at about 150 ° C. for 20 minutes, and the solvent is dried and dried. Imidization was carried out. As a result, a smooth phase change heating layer 5 was formed, and the aluminum core 2 was pulled out.

Thereafter, a heat-shrinkable tube 6 made of a fluororesin PFA (perfluoroalkoxy) is provided on the phase-change heating layer 5.
And one end was sealed, and gradually heated to 300 ° C. from the open end of the other end while reducing the pressure with a rotary pump to complete the imidization. The open end is then sealed and 10 minutes per minute
The fixing roller of Example 1 was prepared by rapidly cooling at a cooling rate of not less than ° C.

(Example 2) PET (polyethylene terephthalate: trade name Mylar) quenched by a shot in molten water was dried and pulverized, and dispersed in a polyimide precursor in the same manner as in Example 1 to obtain a coating liquid. Thereafter, the core metal 2 subjected to centrifugal coating was heated in the same manner as in Example 1 to form a fixing roller 1, and rapidly cooled at a cooling rate of 50 ° C. or more per minute to form a fixing roller of Example 2.

(Example 3) PET (polyethylene terephthalate: trade name Mylar) quenched by a shot in molten water was dried and pulverized to obtain fine particles. These fine particles and CB
(Carbon black) in a ratio of 5: 5 by weight was dispersed in a polyimide precursor in the same manner as in Example 2 to obtain a coating liquid. Thereafter, the core metal 2 which was centrifugally applied in the same manner as in Example 1 was heated to complete imidization, and was heated at 50 min / min.
The fixing roller of Example 3 was prepared by rapidly cooling at a cooling rate of not less than ° C.

(Comparative Example 1) The coating liquid in which Se was dispersed in Example 1 was applied by spray coating to a core 2 made of aluminum at a uniform concentration. After natural drying and preheating, cover the heat-shrinkable tube 6 made of fluororesin PFA, seal one end, and gradually heat to 300 ° C. while reducing the pressure with a rotary pump from the open end with the other end open. And the imidization was completed. Thereafter, the open end was sealed, and quenched at a cooling rate of 10 ° C./min or more per minute in the same manner as in Example 1 to produce a fixing roller of Comparative Example 1.

(Comparative Example 2) The coating liquid in which PET was dispersed in Example 2 was applied at a uniform concentration to a core metal 2 made of aluminum by spray coating. Thereafter, the cored bar 2 was heated in the same manner as in Example 2, and then rapidly cooled at a cooling rate of 50 ° C. or more per minute to prepare a fixing roller of Comparative Example 2.

Comparative Example 3 Example 1 was repeated except that an aluminum cylindrical mold 11 not coated with a fluororesin was used instead of the aluminum cylindrical mold 11 used in Example 1.
A fixing roller was prepared by the same operation as described above. 150 degrees C
After the preliminary drying, the aluminum cored bar 2 was pulled out. However, the coating layer as the phase change heat generating layer 6 was in close contact with the cylindrical mold 11, and the coating layer was torn off when forcibly pulled out.

In place of the aluminum cylindrical mold 11,
If the temporary support is formed from a glass material such as hard glass, the fabrication of the temporary support becomes easy, and the releasability of the phase change heat generating layer 6 is also improved.

(Comparative Example 4) A fixing roller of Comparative Example 4 was obtained by covering a heat-shrinkable tube made of a fluororesin PFA on a cored bar 2 made of aluminum without providing a phase-change heating layer.

In the roller of Comparative Example 1, spot-like aggregates are generated in the phase change heat generating layer 5 to cause unevenness of the surface. In the roller of Comparative Example 2, the phase change heat generating layer 5 and the surface protective layer 4 And large bubbles were generated. On the other hand, the rollers of the first and second embodiments do not have these disadvantages.
An excellent phase change heat generating layer 5 and a surface protective layer 6 were obtained.

In Examples 1 to 3 and Comparative Examples 1 and 2,
4 was incorporated into a fixing device of an electrophotographic copying machine M210 manufactured by Ricoh Co., Ltd.
We examined the rise of the surface temperature of the rollers in the actual machine while heating with.

The results are shown in FIG. 4. As compared with the roller having no phase change heat generating layer 5 of Comparative Example 4, all the other rollers have an effect of promoting heat generation. In the fixing rollers of Examples 1 to 3, it was found that the target toner fixing temperature reached earlier than the fixing rollers of Comparative Examples 1 and 2, although it was delayed in the initial stage of rising, and all showed good rising temperatures. Further, in the fixing roller containing the heat conductive material of Example 3, the rise was earlier from the initial stage and the toner reached the fixing temperature earlier than in the fixing rollers of Examples 1 and 2.

[0066]

As described above, according to the present invention,
The following effects can be expected.

According to the first aspect of the present invention, since the density of the heat generating material in the phase change heat generating layer is higher on the surface side,
The calorific value is relatively high on the surface side, and the surface of the fixing roller is efficiently heated.

According to the second aspect of the present invention, the polyimide is chemically and thermally stable, so that the binder can maintain its shape even if the melting and crystallization cycle is used repeatedly, and the phase transition heat is generated. No material aggregation occurs.

According to the third aspect of the present invention, the thermal conductivity of the phase change heat generating layer is improved, and the temperature rise of the fixing roller is further accelerated. An effective method of manufacturing a fixing roller is provided.

According to the sixth aspect of the present invention, the particles of the phase change exothermic material can be fixed before the particles are melted.

According to the seventh and eighth aspects of the present invention, it is easy to obtain a phase-change heating layer without damage.

According to the ninth aspect of the present invention, the use of the polyimide precursor makes it easy to disperse the particles of the phase-change exothermic material. Further, since the layer can be formed by a wet coating method, the phase-change exothermic layer is formed. Processing into an arbitrary form becomes easy.

According to the tenth aspect of the present invention, no moisture and bubbles remain in the phase change heat generating layer. Further, according to this fixing roller, deformation due to the generation of bubbles and the like due to heating during use during molding of the roller is reduced. Further, since moisture generated by the imidization reaction is removed from the open end, a fixing roller having a protective layer can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a layer configuration of a fixing roller 1 of the present invention.

FIG. 2 is a schematic perspective view illustrating a manufacturing process of the fixing roller 1 of the present invention.

FIG. 3 is a process diagram illustrating a manufacturing process of the fixing roller 1 of the present invention.

FIG. 4 is a graph showing a temperature rise curve of a roller surface temperature for explaining the performance of fixing rollers of an example and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixing roller 2 ... Core metal 3 ... Heat generation material of phase change 4 ... Binder 5 ... Heat generation layer of phase change 6 ... Protective layer (surface layer)

Claims (10)

[Claims] 1. A fixing roller having a phase change heat generating layer in which a phase change heat generating material that generates heat energy at the time of phase transition is dispersed in a binder, wherein the phase change heat generating material includes the phase change heat generating layer. A density gradient is increased toward a circumferential outer surface of the fixing roller. 2. The fixing roller according to claim 1, wherein the binder is polyimide. 3. The fixing roller according to claim 1, wherein the phase-change heating layer contains a good heat conductive material. 4. A tubular coating method in which a binder coating liquid in which a phase-change heat-generating material that generates thermal energy at the time of phase transition is dispersed is applied to a temporary support inner surface having a substantially cylindrical inner surface in a hollow cylindrical shape. A film applying step; a density gradient applying step of increasing a density gradient of the phase-change exothermic material in the cylindrical coating film toward a centrifugal force direction by rotating the temporary support at a high speed; and supporting the temporary support in the temporary support. A core metal insertion step of inserting a body core metal, a bonding step of bonding the coating film to the support core metal, and a removal step of taking out the core metal together with the phase transition heating layer from the temporary support. The method for manufacturing a fixing roller according to claim 1, wherein: 5. A binder coating liquid in which particles of a phase change heat-generating material that generates heat energy at the time of a phase transition from an amorphous state to a crystalline state are dispersed in a temporary support having a substantially cylindrical inner surface. A coating liquid applying step of applying a film in a film form; a density gradient applying step of increasing a density gradient of the phase change exothermic material in the coating film toward a centrifugal force direction by rotating the temporary support at a high speed; A core metal insertion step of inserting a support core metal into the temporary support, a bonding step of bonding the coating film to the support core metal, and a removal step of taking out the core metal from the temporary support together with the phase-change heating layer; The method for manufacturing a fixing roller according to claim 1, wherein a surface layer applying step of applying a surface layer to an outer surface of the phase change heat generating layer is sequentially performed. 6. The method according to claim 4, wherein the joining step is performed by heating. 7. The method according to claim 4, wherein the temporary support has an inner surface coated with a fluororesin. 8. The method according to claim 4, wherein the temporary support is glass. 9. The binder coating liquid is a polyimide precursor coating liquid, and the coating is heated under reduced pressure at any stage after the density gradient applying step to cure the polyimide precursor. The method according to claim 4, wherein the steps are combined. 10. The method according to claim 5, wherein the surface layer is formed by opening at least one end, and the curing step is performed while removing moisture from the open end.