JP2020016770A - Heating body - Google Patents

Abstract

To provide a heating body which detects partial breakage in a fixing belt, and thereby blocks energization to a heating layer, and thereby prevents excessive rise in temperature in a local portion.SOLUTION: A heating body has a heating layer, an insulation layer and a detection layer laminated in this order, in which the detection layer is energized via an electrode part and is one line shape in an inter-electrode direction, and a line interval of the line shape is 0.03 mm or more and 10 mm or less. The heating body has a heating layer, an insulation layer and a detection layer laminated in this order, in which the detection layer contains a heat-resistant resin and conductive particles.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heating element used for a fixing belt mounted on an image forming apparatus or the like.

  In the past, a “resistance heating seamless fixing belt having a heating layer made of a polyimide resin in which carbon nanomaterials and filamentary metal fine particles are dispersed” has been proposed (for example, see JP-A-2007-272223). This resistance heating seamless fixing belt is a seamless fixing belt that generates heat when energized, and is used as a main component of an image fixing unit of an electrophotographic image forming apparatus.

  However, such a resistance heating seamless fixing belt causes an excessive temperature rise in the heating layer when a current is applied for rapid startup or when the resistance heating seamless fixing belt is partially torn. There is a problem, and it is necessary to provide a means for ensuring safety when used for electrophotography.

  In order to solve such a problem, a fixing method that interrupts power supply to a current-carrying film that causes an abnormal temperature rise based on a comparison based on the outputs of the first and second temperature detecting means has been proposed in the past. An "apparatus" has been proposed (for example, see Japanese Patent Application Laid-Open No. 2018-045021). The temperature detecting means in the fixing device measures the temperature by directly contacting the thermistor with the film, and detects an abnormal temperature such as an excessive temperature rise, thereby cutting off the current supply to the heat generating layer.

JP 2007-272223 A JP 2018-045021A

  However, when such a temperature detection method is used, when the jamming of the user in the fixing belt, for example, local overheating occurs when the heating element is partially torn by a tweezer, a cutter, or the like, Depending on the contact position of the thermistor, there has been a problem that an excessive temperature rise cannot be detected accurately. For this reason, there is a demand for a heating element capable of detecting an excessive temperature rise that occurs locally due to partial breakage of the fixing belt and interrupting the current supply to the heating layer.

  It is an object of the present invention to provide a heating element that detects the occurrence of partial breakage in the heating element, cuts off the power supply to the heating layer, and prevents an excessive temperature rise that occurs locally. .

  The heating element of the present invention has a heating layer, an insulating layer, and a detection layer laminated in this order. Note that the “detection layer” here is energized through the electrode portion, is provided in a linear shape in the direction between the electrode portions, and may be formed in one or a plurality of linear shapes. . Further, the detection layer is provided so that a line interval (a distance between linear detection layers) is 0.03 mm or more and 10 mm or less. Further, the detection layer is provided such that the width of the line shape (thickness of the line shape) is 0.03 mm or more and 10 mm or less. In the electrode portion provided in the detection layer, a part of the detection layer may function as an electrode portion, the electrode portion may be directly bonded to the detection layer, or via one or more conductive resin layers. It may be indirectly joined to the electrode part.

  Further, the shape of the heating element of the present invention may be tubular or sheet-like. When the shape of the heating element is tubular, the detection layer is provided in a linear shape and a shape in which a spiral or straight line is bent plurally in a Z-shape or a shape in which a plurality of bents are formed in a U-shape. The method of providing the spiral shape may be right-handed or left-handed, and the U-shape may be provided in a U-shape with respect to the direction between the electrode portions, so that the spiral shape is perpendicular to the direction between the electrode portions. It may be provided in a U-shape, or may be provided with a plurality of linear detection layers (see FIGS. 6 to 9). When the shape of the heating element is a sheet shape, the detection layer has a linear shape and a shape in which a plurality of lines are obliquely bent or a shape in which a straight line is bent in a Z shape or a plurality of U-shaped shapes. Is provided. By providing the detection layer in the above-described shape, the detection layer is broken, and the power supply to the heat generation layer is cut off by the relay switch.

The heating layer provided on the heating element also generates heat when energized, and is provided with a pair of electrode portions for energizing, and the electrode portions are preferably arranged on both sides of the heating layer. The electrode portion may be provided so as to be exposed on the inner peripheral surface, may be provided so as to be exposed on the outer peripheral surface, or may be embedded. Further, a part of the heat generating layer may function as an electrode portion. The heat generating layer may be directly joined to the electrode portion, or may be indirectly joined to the electrode portion via one or more conductive resin layers. In addition, the lamination of the heat generating layer, the insulating layer, and the detection layer in this order may be performed either on the outer surface side or the inner surface side with respect to the heat generation layer, and when formed on the outer surface side, the outer side of the detection layer Further, an elastic layer or a release layer may be further provided.

It is an appearance perspective view of a resistance heating seamless tubular object concerning an embodiment of the invention. It is the external appearance perspective view at the time of the detection layer shaping | molding which concerns on embodiment of this invention, and AA sectional drawing. 1 is a simplified configuration diagram of a fixing device incorporating a resistance heating seamless tubular article according to an embodiment of the present invention. FIG. 4 is a sectional view of a simplified configuration diagram of the fixing device of FIG. 3. It is a figure showing a part of manufacturing process of a resistance heating seamless tubular object concerning an embodiment of the invention. FIG. 4 is an external perspective view of an example (molding in a direction between electrode portions) at the time of forming a U-shaped detection layer according to the embodiment of the present invention. FIG. 4 is an external perspective view showing an example (forming in a vertical direction between electrode portions) of a U-shape detection layer according to an embodiment of the present invention. It is an external appearance perspective view at the time of character-shaped shaping of detection layer Z concerning an embodiment of the invention. It is an external appearance perspective view at the time of shape | molding the spiral shape of the detection layer which concerns on embodiment of this invention.

<Configuration of heating element>
The heating element according to the embodiment of the present invention is a sheet-like or tubular heating element. Here, the details of the tubular heating element as shown in FIG. 1 (hereinafter referred to as “resistance heating seamless tubular article”) will be described, and the description of the sheet-like heating element other than the shape of the detection layer will be omitted. .

  The resistance heating seamless tubular article 100 according to the embodiment of the present invention mainly includes a heating layer 110, an insulating layer 130, and a detection layer 140, and an elastic layer 150 and a release layer 160 are provided according to purposes. Hereinafter, the heat generating layer 110, the insulating layer 130, and the detection layer 140, which are main components thereof, will be described in detail.

(1) Heating Layer The heating layer 110 is a seamless tubular layer, as shown in FIG. 1, and is not particularly limited as long as it is mainly a material that can withstand the temperature during use of the resistance heating seamless tubular article 100. Among them, it is preferable to be formed from a heat resistant material. Examples of such a heat-resistant material include a heat-resistant resin. In the resistance heating seamless tubular article 100 according to the present embodiment, the heat-resistant resin is preferably a resin containing a polyimide resin as a main component, and more preferably the polyimide resin itself. When the heat-resistant resin is a resin containing a polyimide resin as a main component, other heat-resistant resins such as polyamideimide and polyether sulfone are added to the heat-resistant resin within a range that does not impair the essence of the present invention. May be done. When a heat-resistant resin is used in the heat generating layer 110, the heat-resistant resin contains a conductive material, and can contain a conductive material such as carbon nanotubes and carbon nanofibers.

  In this embodiment, the heat generation layer 110 is provided with an electric insulating material such as alumina, boron nitride, aluminum nitride, silicon carbide, titanium oxide, silica, potassium titanate, or silicon nitride for the purpose of improving thermal conductivity and the like. Particles, such as potassium titanate fiber, acicular titanium oxide, aluminum borate whisker, tetrapotted zinc oxide whisker, sepiolite, glass fiber and other fibrous particles, montmorillonite, talc, etc. Clay minerals may be added to such an extent that the essence of the present invention is not impaired.

(1-2) Electrodes The electrodes 120 may be provided at both ends of the heat generating layer 110 as shown in FIG. 1, and are provided so as to be exposed to the outer surface at both ends of the heat generating layer 110. This electrode can be formed, for example, from a silver paste or the like. As the silver paste, for example, the one disclosed in International Publication No. 08/016148 can be used. Then, when the resistance heating seamless tubular article 100 is used, this electrode comes into contact with the power supply member. As a result, power is supplied to the heat generating layer 110 disposed in contact with the electrode, and the heat generating layer 110 generates resistance heat. In addition, as a power supply member, a power supply brush, a power supply roll, a power supply bar, etc. are mentioned, for example.

(2) Insulating Layer The insulating layer 130 is preferably formed of a heat-resistant material that can withstand the heat generation temperature of the heat generation layer. Examples of such a heat-resistant material include a heat-resistant resin similar to the heat-generating layer, and a resin containing a polyimide resin as a main component is preferable, and a polyimide resin itself is more preferable. In addition, the thickness of the insulating layer is appropriately adjusted based on the insulating property, thermal conductivity, and the like.

(3) Detecting Layer The detecting layer 140 is not particularly limited as long as it is mainly made of a material that can withstand the temperature at the time of use of the resistance heating seamless tubular article 100 and has conductivity, but among them, it is preferable to be formed from a heat-resistant material. . Examples of such a heat-resistant material include the same heat-resistant resin as the heat-generating layer. In the detection layer 140, a conductive material is contained in the heat-resistant resin, and in controlling the resistance value of the detection layer 140, as the conductive material, nickel, copper, silver, gold, chromium, molybdenum, Metals such as tungsten and titanium, or alloys such as nichrome and constantan, or graphite, expanded graphite, exfoliated expanded graphite, carbon black, acetylene black, carbon nanotube, vapor grown carbon fiber, carbon fiber, carbon microcoil, and graphene Etc. can be used.

(3-1) Electrode In the detection layer 140, electrodes 180 may be provided at both ends of the detection layer as shown in FIG. 2, and are arranged so as to be exposed to the outer surface at both ends of the detection layer 140. I have. This electrode can be made of the same material as the electrode provided in the heat generating layer. Then, when the resistance heating seamless tubular article 100 is used, this electrode comes into contact with the power supply member like the electrode provided on the heating layer. Thus, power is supplied to the detection layer 140 provided in contact with the electrode, and the detection layer 140 is energized. In addition, as a power supply member, a power supply brush, a power supply roll, a power supply bar, etc. are mentioned, for example.

<An example of a method for manufacturing a resistance heating seamless tubular article>
The resistance heating seamless tubular article 100 according to the present embodiment mainly includes a heating layer forming step, an electrode forming step, an insulating layer forming step, a detection layer forming step, an electrode forming step, a primer coating step, an elastic layer forming step, a primer, It is manufactured through a coating step, a release layer forming step, a baking step, and a demolding step. However, this manufacturing method is only an example and does not limit the present invention. Hereinafter, each of the above manufacturing steps will be described in detail.

(1) Heating Layer Forming Step In the heat generating layer forming step, as shown in FIG. 5, the conductive material-containing polyimide precursor solution VS is uniformly spread on the outer peripheral surface of the cylindrical core body 610 using a ring die 620. After the application, the core 610 with the applied film CV is heated. The heating temperature at this time is preferably a temperature at which the organic polar solvent contained in the polyimide precursor solution VS is volatilized but imidization does not proceed, for example, a temperature in the range of 200 ° C. or more and 250 ° C. or less. However, the temperature may be raised stepwise to 300 ° C. to 450 ° C. In such a case, when carbon nanotubes or carbon nanofibers are used as the conductive material, the ring-shaped dies are aligned and aligned in substantially one direction toward the traveling direction.

  Note that the conductive material-containing polyimide precursor solution is obtained by mixing a conductive material such as carbon nanotubes and carbon nanofibers with a polyimide precursor solution prepared as follows. The method of adding the conductive material is not particularly limited, and may be a method of directly adding the conductive material to the polyimide precursor solution, or a method of adding the conductive material during the preparation of the polyimide precursor solution.

The polyimide precursor solution is prepared as follows.
First, a diamine solution is prepared by dissolving at least one diamine in an organic polar solvent, and at least one tetracarboxylic dianhydride is added to the diamine solution to form a diamine and a tetracarboxylic dianhydride. Is polymerized to prepare a polyimide precursor solution. At this time, the environmental temperature is preferably in the range of 10 ° C. or more and 90 ° C. or less. Further, the solid content concentration is determined by application conditions, and is usually within a range of 10% by mass or more and 30% by mass or less. Further, as the polymerization reaction between the diamine and the tetracarboxylic dianhydride proceeds, the viscosity of the solution increases, but upon use, the solution can be diluted with a solvent to a desired viscosity before use. Depending on the manufacturing conditions and working conditions, it is usually used at a viscosity of 1 poise to 5,000 poise. To apply this polyimide precursor solution to the surface of a mold by a casting method, the viscosity of the polyimide precursor solution is required. It is preferably within a range of 10 poise to 1,500 poise, and more preferably within a range of 50 poise to 1,000 poise.

  The organic polar solvent from which the polyimide precursor solution can be prepared includes, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, , 3-dimethyl-2-imidazolidinone, N-methylcaprolactam, hexamethylphosphoric triamide, 1,2-dimethoxyethane, diglyme, triglyme and the like. Among these diamines, N, N-dimethylacetamide (DMAC) and N-methyl-2-pyrrolidone (NMP) are particularly preferred. Note that these organic polar solvents may be used alone or in combination. An aromatic hydrocarbon such as toluene and xylene may be mixed with the organic polar solvent.

  Examples of the diamine from which the above polyimide precursor solution can be prepared include, for example, paraphenylenediamine (PPD), metaphenylenediamine (MPDA), 2,5-diaminotoluene, 2,6-diaminotoluene, and 4,4 ′. -Diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 2,2-bis (trifluoromethyl) -4,4'- Diaminobiphenyl, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane (MDA), 2,2-bis- (4-aminophenyl) propane, 3,3′-diaminodiphenylsulfone (33DDS), 4, 4'-diaminodiphenyl sulfone (44DDS), 3,3'-diaminodiphenyl sulfide, 4, '-Diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether (34 ODA), 4,4'-diaminodiphenyl ether (ODA), 1,5-diaminonaphthalene, 4,4'-diaminodiphenyl Diethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 1,3-bis (3-aminophenoxy) benzene (133APB), 1,3-bis (4-aminophenoxy) Benzene (134APB), 1,4-bis (4-aminophenoxy) benzene, bis [4- (3-aminophenoxy) phenyl] sulfone (BAPSM), bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS ), 2,2-bis [4- (4-A Nophenoxy) phenyl] propane (BAPP), 2,2-bis (3-aminophenyl) 1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) 1, Aromatic diamines such as 1,1,3,3,3-hexafluoropropane and 9,9-bis (4-aminophenyl) fluorene, aliphatic diamines such as tetramethylenediamine, hexamethylenediamine, cyclohexanediamine, isophoronediamine And alicyclic diamines such as norbornanediamine, bis (4-aminocyclohexyl) methane, and bis (4-amino-3-methylcyclohexyl) methane. It should be noted that these diamines may be used as a mixture of two or more kinds. Among these diamines, paraphenylenediamine (PPD), metaphenylenediamine (MPDA), 4,4′-diaminodiphenylmethane (MDA), 3,3′-diaminodiphenylsulfone (33DDS), 4,4′- Diaminodiphenylsulfone (44DDS), 3,4'-diaminodiphenylether (34ODA), 4,4'-diaminodiphenylether (ODA), 1,3-bis (3-aminophenoxy) benzene (133APB), 1,3-bis (4-aminophenoxy) benzene (134APB), bis [4- (3-aminophenoxy) phenyl] sulfone (BAPSM), bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS), 2,2-bis [4- (4-aminophenoxy) phenyl] pro Emissions (BAPP) is preferable.

  Further, tetracarboxylic dianhydrides from which the above polyimide precursor solution can be prepared include pyromellitic dianhydride (PMDA), 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4 , 5,8-Naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,3 3,3′4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride Anhydride, 2,3,3 ′, 4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), bis (3,4-dicarboxy) Phenyl) sulfone dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ) Ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2,2-bis [3,4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA), 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride, oxydiphthalic anhydride (ODPA), bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfoxide Dianhydride, thiodiphthalic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetraca Boric acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorene dianhydride and 9,9-bis [4- ( Aromatic tetracarboxylic dianhydrides such as 3,4'-dicarboxyphenoxy) phenyl] fluorene dianhydride, cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride, , 4-Dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride. It should be noted that a mixture of two or more of these tetracarboxylic dianhydrides may be used without any problem. Among these tetracarboxylic dianhydrides, in particular, pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4 Preferred are 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 2,2-bis [3,4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA), and oxydiphthalic anhydride (ODPA).

  In the present embodiment, it is particularly preferable to use paraphenylenediamine as the diamine and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as the tetracarboxylic dianhydride. Polyimide resins obtained from these monomers have excellent mechanical properties and are tough, and do not soften or melt as thermoplastic resins even when the temperature of the resistance heating seamless tubular article 100 increases, and have excellent heat resistance. This is because

  If necessary, a resin such as polyamideimide or polyethersulfone may be added to the polyimide precursor solution as long as the essence of the present invention is not impaired.

  In addition, the polyimide precursor solution, within a range that does not impair the properties of the present invention, a dispersant, a solid lubricant, an anti-settling agent, a leveling agent, a surface conditioner, a moisture absorber, an anti-gelling agent, an antioxidant Adds known additives such as UV absorbers, light stabilizers, plasticizers, anti-skinning agents, surfactants, antistatic agents, defoamers, antibacterial agents, fungicides, preservatives, thickeners, etc. May be done. Further, a stoichiometric or more dehydrating agent and an imidization catalyst may be added to the polyimide precursor solution.

  The polyimide precursor solution is preferably subjected to a treatment such as filtration and defoaming before use.

(1-2) Heating Layer Heating Step When the coating film CV is formed on the core body 610, a baking treatment is performed to form a heating layer. The firing temperature at this time is preferably in the range of 350 ° C. or more and 400 ° C. or less. Further, the processing time is preferably in the range of 30 minutes or more and 2 hours or less. This is because imidization of the heat-generating resin layer 110 can be completed.

(2) Electrode Forming Step In the electrode forming step, first, a silver paste is applied to the outer peripheral surfaces of both ends of the heat generating layer 110, and then the applied thickness of the silver paste is made uniform by a known method. Then, the electrode 120 can be formed by heating the core on which the silver paste is applied to the heat generating layer 110. In addition, it is preferable that a polyimide precursor is added as a binder resin to the silver paste. This is because not only can the adhesiveness with the heat generating layer 110 be improved, but also the electrode 120 maintains a state of being firmly bonded to the heat generating layer 110 even at a high temperature. As such a silver paste, for example, the one disclosed in International Publication No. 08/016148 can be used.

(3) Insulating Layer Forming Step In the insulating layer forming step, a polyimide precursor solution is applied to the surface of the core body 610 on which the heat generating layer 110 is formed in the same manner as in the heat generating layer forming step with the electrodes 120 being masked. Formed by The polyimide precursor solution has the same composition as the polyimide precursor solution used for forming the heat generating layer 110. If necessary, the polyimide precursor solution may contain polyamideimide or polyimide within a range that does not impair the essence of the present invention. A resin such as ether sulfone may be added. It is preferable that the insulating layer 130 be provided so that a part of the electrode layer 120 provided at both ends of the heat generating layer 110 is exposed and the insulating layer 130 is overlapped so as not to hinder the power supply to the heat generating layer 110.

  In the heating step of the insulating layer, the firing temperature is preferably in a range of 350 ° C. or more and 400 ° C. or less. Further, the processing time is preferably in the range of 30 minutes or more and 2 hours or less.

(4) Detecting Layer Forming Step In the detecting layer forming step, the surface of the core body 610 on which the heat generating layer 110 and the insulating layer 130 are formed in the state where the electrode 120 is masked is formed into one linear shape in the direction between the electrode portions. The screen is formed by applying a detection layer in a spiral shape using screen printing as shown in FIG. In the example of the present embodiment, the detection layer is formed by applying a polyimide precursor solution containing a conductive material to a heat-resistant resin. The detection layer 140 is provided on the insulating layer 130 to such an extent that a current flowing through the heating layer 110 does not flow from the end of the heating element via the insulating layer 130.

  When the detection layer is provided, the detection layer is provided so that the line interval is 0.03 mm or more and 10 mm or less, preferably 0.03 mm or more and 3 mm or less, and more preferably 0.03 mm or more and 0.3 mm or less. Further, the width of the linear shape of the detection layer is provided to be 0.03 mm or more and 10 mm or less, preferably 0.03 mm or more and 3 mm or less, and more preferably 0.03 mm or more and 0.3 mm or less.

  The detection layer 140 may be formed as long as it can be formed into a single linear shape. In addition to screen coating, dipping, dispenser coating, inkjet printing, sputtering, sink evaporation, inorganic electrolytic plating, or the like can be used. In the vapor deposition method, the detection layer 140 composed of a metal thin film can be formed directly on the insulating layer 130. In the inorganic electrolytic plating method, after the surface modification, activation and catalysis of the insulating layer 130, inorganic electrolytic plating is performed. The detection layer 140 made of a metal thin film is formed. As the metal thin film formed by plating or the like, nickel, a nickel alloy, or the like can be used.

  In the surface modification, activation and catalysis, it is appropriately adjusted depending on the metal thin film material to be used.For example, when a metal thin film made of nickel is used, it is brought into contact with a palladium and tin colloid catalyst, and sulfuric acid or hydrogen sulfate is used. A treatment such as oxidation of tin and reduction of palladium by bringing a sodium solution into contact with the surface of the insulating layer 130 can be given.

  The material used for the detection layer is not particularly limited as long as it has a resistance enough to allow a current to flow, and is a material that can withstand the temperature during use of the resistance heating seamless tubular article 100.

  Further, in the example of the present embodiment, the detection layer is formed in a spiral shape, but the detection layer may have a shape in which a straight line is bent plurally in a Z shape or a shape in which a straight line is bent plurally in a U shape. Good. Furthermore, in the case of a sheet shape, the shape may be a shape bent a plurality of oblique lines, a shape bent a plurality of straight lines in a Z shape, or a shape bent a plurality of U-shapes.

(4-2) Electrode Forming Step In the electrode forming step, first, a silver paste is applied to the outer peripheral surfaces of both ends of the detection layer 140, and then the applied thickness of the silver paste is made uniform by a known method. The electrode 180 can be formed by heating the core on which the silver paste is applied to the detection layer 140. In addition, it is preferable that a polyimide precursor is added as a binder resin to the silver paste. This is because not only can the adhesion with the detection layer 140 be good, but also the electrode 180 maintains a state of being firmly adhered to the detection layer 140 even at a high temperature. As such a silver paste, the one disclosed in International Publication No. 08/016148 can be used similarly to the electrode provided on the heating layer.

(5) Primer Coating Step In the primer coating step, the core 610 on which the detection layer 140 is formed is dipped in a primer solution while the electrodes 120 and 180 are masked, so that the primer solution is applied to the outer peripheral surface of the detection layer 140. Is uniformly applied, and the coating film is heated together with the core 610 and the like to form a primer layer. The heating temperature at this time is preferably, for example, a temperature in the range of 200 ° C. or more and 250 ° C. or less.

The primer layer is a layer having a role of bonding the detection layer 140 and the elastic layer 150, and is made of an adhesive resin such as a silicone resin or an acrylic resin. The thickness of the primer layer is preferably in the range from 3 μm to 10 μm.

(6) Elastic Layer Forming Step In the elastic layer forming step, the surface of the core body 610 on which the heat generating layer 110, the insulating layer 130, the detection layer 140, the electrode layer 180, and the primer layer are formed in a state where the electrodes 120 and 180 are masked. A rubber or elastomer such as liquid silicone rubber or fluorine rubber is applied in the same manner as in the heating layer molding step, and the rubber or elastomer such as liquid silicone rubber or fluorine rubber is heated stepwise to perform primary vulcanization. Then, the elastic layer 150 is formed by performing secondary vulcanization.

  In the case of the present embodiment, after the liquid silicone rubber is evenly applied to the outer surface of the primer layer, the liquid silicone rubber is heated stepwise to perform primary vulcanization and secondary vulcanization, thereby performing secondary vulcanization silicone. The elastic layer 150 made of rubber is formed.

(7) Primer coating step In the primer coating step, while the electrode 120 is masked, a primer solution containing a dispersoid containing a fluororesin, a water-soluble heat-resistant resin such as a water-soluble polyamideimide resin or a water-soluble polyimide resin is heated. By dipping the core 610 on which the layer 110, the insulating layer 130, the detection layer 140, the primer layer, and the elastic layer 150 are formed, the outer peripheral surface of the elastic layer 150 is uniformly coated with the primer liquid. Then, the core body 610 with the coating film is heated. The heating temperature at this time is preferably, for example, a temperature in the range of 200 ° C. or more and 250 ° C. or less.

(8) Release Layer Forming Step In the release layer forming step of the present embodiment, after the fluororesin dispersion liquid is applied, the coating film is dried, and the fluororesin dispersion liquid is applied on the primer layer. A coating is formed.

  In the present embodiment, the release layer 160 is formed using a fluororesin dispersion liquid, but the release layer 160 is formed from at least one selected from the group consisting of fluororesin, silicone rubber, and fluororubber. Is preferred. Examples of the fluororesin used for the fluororesin dispersion include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) And these may be used alone or as a mixture.

(9) Firing Step In the firing step, after the masking is removed, the one obtained in the release layer forming step is fired to obtain the resistance heating seamless tubular article 100. The firing temperature at this time is preferably in the range of 340 ° C. or more and 400 ° C. or less. Further, the processing time is preferably in the range of 10 minutes to 2 hours.

(10) Demolding step In the demolding step, the resistance heating seamless tubular article 100 is extracted from the core body 610.

<Fixing device of electrophotographic image forming apparatus>
Here, an embodiment of an image fixing device in which the resistance heating seamless tubular article 100 according to the present embodiment is incorporated will be described. As shown in FIGS. 3 and 4, the image fixing device 400 mainly includes the resistance heating seamless tubular article 100 according to the present embodiment, the belt support 170, the pressure roll 300, and the power supply roll 210. ing.

  The resistance heating seamless tubular article 100 is as described above. The belt support 170 is formed of a heat-resistant insulating resin such as polyphenylene sulfide, polyamide imide, polyether ether ketone, and liquid crystal polymer, and mainly includes a cylindrical portion 171 and a belt guide portion 172. As shown in FIG. 4, the cylindrical portion 171 is rotatably arranged inside the resistance heating seamless tubular article 100. The belt guide portion 172 functions as a stopper when the resistance heating seamless tubular article 100 meanders in the width direction. The pressure roll 300 includes a roll body 310 and a shaft 320. The shaft 320 extends on both sides along the rotation axis of the roll body 310, and is connected to a drive motor (not shown). As shown in FIG. 3 and FIG. 4, the roll body 310 is pressed against the resistance heating seamless tubular article 100, and as a result, a nip portion N is formed between the roll body 310 and the resistance heating seamless tubular article 100. That is, when the drive motor is driven, the roll body 310 rotates about the rotation axis, and the resistance heating seamless tubular article 100 pressed against the pressure roll 300 follows. Then, as shown in FIG. 4, the copy paper PP on which the unfixed toner image TN is formed is sequentially fed into the nip portion N, and the unfixed toner image TN is sequentially thermally fixed to the copy paper PP. You. The power supply roll 210 is connected to an AC power supply 230 via a lead wire 220 and is in contact with the electrode 120 of the resistance heating seamless tubular article 100. For this reason, electricity is supplied to the resistance heating seamless tubular article 100 from the AC power supply 230 via the power supply roll 210. When current is applied to the resistance heating seamless tubular article 100, the heating layer 110 generates resistance heating as described above. The detection layer 140 is connected to the DC current 240 via a lead wire, and is connected in series to the excitation relay switch 600 to be energized.

<Modification>
(A)
Although not particularly mentioned in the above embodiment, a base layer may be provided on the inner peripheral side of the heat generating layer 110. The base layer is a seamless tubular layer, and is preferably formed of a heat-resistant insulating material that can withstand the temperature during use of the resistance heating seamless tubular article 100. Examples of such a heat-resistant insulating material include special stainless steel, heat-resistant resin, and the like. The heat-resistant resin is preferably a resin containing a polyimide resin or a silicone rubber as a main component, and more preferably a polyimide resin itself. When the resistance heating seamless tubular article 100 is incorporated in an image fixing section of an electrophotographic image forming apparatus as a fixing tube or a fixing belt, it is preferable that the base layer has mechanical properties enough to withstand the operation.

(B)
Although not particularly mentioned in the above embodiment, a configuration without an elastic layer provided between the detection layer 140 and the release layer 160 may be employed. In that case, the primer coating step and the elastic layer forming step provided between the detection layer 140 and the elastic layer 150 may be omitted from the steps.

(C)
In the resistance heating seamless tubular article 100 according to the previous embodiment, the electrode 120 is provided so as to be exposed on the outer peripheral side. However, the electrode 120 is provided so as to be exposed on the inner peripheral side of the heating resin layer 110. You may. Further, as described in Modification Example (A), when the base layer is provided on the inner peripheral side of the heat generating resin layer 110, the base layer is provided so that the electrode 120 is exposed on the inner peripheral side. However, the electrode 120 may be embedded in the base layer as long as the base layer is provided with conductivity.

(D)
In the resistance heating seamless tubular article 100 according to the above embodiment, a plurality of detection layers may be provided, and in that case, the detection layers may be provided in different shapes. When a plurality of sensing layers are provided, it is preferable that an insulating layer is further interposed between the sensing layers.

<Example>
Hereinafter, the heating element (resistance heating seamless tubular article) according to the present embodiment will be described in more detail with reference to examples. It should be noted that these embodiments do not embody the present invention.

(1) Preparation of Polyimide Precursor Solution A 100 g of a polyamic acid solution (composition BPDA / PPD, solid content 19% by mass) and 12 g of carbon nanotubes (hereinafter abbreviated as “CNT”) are mixed to prepare a polyimide precursor solution A. Prepared. At this time, the amount of CNT added is calculated so that the CNT accounts for 30% by volume with respect to the solid content of the polyimide precursor solution A.

(2) Preparation of polyimide precursor solution B 50 g of a polyamic acid solution (composition PMDA / ODA, solid content: 19% by mass), 20 g of silver powder, and 2-di-n-butylamino-4,6-dimercapto-1,3,5 0.1 g of triazine (hereinafter abbreviated as “DBDMT”) was mixed to obtain a polyimide precursor solution B.

(3) Preparation of Polyimide Precursor Solution C A polyimide precursor solution C consisting of 100 g of a polyamic acid solution (composition BPDA / PPD, solid content 19% by mass) was obtained.

(4) Preparation of Polyimide Precursor Solution D 10 g of a polyamic acid solution (composition PMDA / ODA, solid content: 19% by mass), 13 g of silver powder and 2-di-n-butylamino-4,6-dimercapto-1,3,5 0.01 g of triazine (hereinafter abbreviated as “DBDMT”) was mixed to obtain a polyimide precursor solution D. At this time, the addition amount of the silver powder is calculated so that the silver powder occupies 40% by volume with respect to the solid content of the polyimide precursor solution D.

(5) Production of resistance-heat-generating seamless tubular article First, a polyimide precursor solution A was uniformly applied to the surface of a cylindrical mold whose surface had been release-treated, and then the coating film was heated at 100 ° C for 10 minutes and at 150 ° C. Heating was sequentially performed for 20 minutes, 250 ° C. for 30 minutes, and 400 ° C. for 15 minutes to obtain a 70 μm-thick polyimide tubular article A.

  Next, the polyimide precursor solution B was uniformly applied to the surface of both ends 25 mm of the polyimide tubular article A, and then the coating was applied at 100 ° C. for 30 minutes, 150 ° C. for 60 minutes, 200 ° C. for 60 minutes, 300 ° C. , And heated at 350 ° C. for 30 minutes in order to remove the solvent and perform imidization to form electrodes having a thickness of 20 μm on both ends of the polyimide tubular article A.

  Next, after uniformly applying the polyimide precursor solution C to the “outer surface of the central portion of the polyimide tubular article A where no electrode is formed”, the coating film was heated at 100 ° C. for 10 minutes, and at 150 ° C. for 20 minutes. Heating was sequentially performed at 250 ° C. for 30 minutes and at 400 ° C. for 15 minutes to form an insulating layer having a thickness of 30 μm.

  Next, a polyimide precursor solution D is spirally applied to the outer peripheral surface of the insulating layer by screen printing, and the coating is applied at 100 ° C. for 10 minutes, at 150 ° C. for 20 minutes, at 250 ° C. for 30 minutes, and at 400 ° C. for 15 minutes. The heating layer was sequentially heated under the conditions of minutes, to form a spiral detection layer having a thickness of 5 μm, a line interval of 10 mm, and a line width of 10 mm. The angle at which the spiral was formed was about 80 ° with respect to the direction between the electrode portions.

  Next, after a polyimide precursor solution B is uniformly applied to a surface having a width of 10 mm from a position 3 mm from both ends of the outer peripheral surface of the insulating layer toward the center thereof, the coating film is heated at 100 ° C. for 30 minutes at 150 ° C. For 60 minutes, at 200 ° C. for 60 minutes, at 300 ° C. for 60 minutes, and at 350 ° C. for 30 minutes to remove the solvent and perform imidization to form an electrode having a thickness of 15 mm on the outer peripheral surface of the insulating layer. Formed.

  Subsequently, a primer liquid was applied to the detection layer other than the electrode portion provided on the detection layer and the outer surface of the exposed insulating layer, and the coating film was heated at 150 ° C. for 10 minutes. After the silicone rubber was uniformly applied to the primer liquid application portion, the silicone rubber was vulcanized by sequentially heating at 150 ° C. for 30 minutes and then at 200 ° C. for 30 minutes to form an elastic layer having a thickness of 300 μm. .

  Subsequently, a primer solution was applied to the outer surface of the elastic layer, and the coating film was heated at 150 ° C. for 10 minutes. Then, after uniformly applying the fluororesin dispersion liquid to the primer-applied portion, the coating film was dried at 60 ° C. for 10 minutes and further baked at 340 ° C. for 10 minutes to form a release layer having a thickness of 20 μm. As a result, a resistance heating seamless tubular article having a thickness of 425 μm, an inner diameter of 20 mm, and a length of 272 mm was obtained.

(6) When a 30 mm × 30 mm break is intentionally caused in the direction between the detection electrode portions due to partial breakage of the resistance heating seamless tubular article, a break in the detection line causes a magnetic field to be generated in the coil in the excitation relay switch. Since the power supply to the heat generating layer was cut off by turning off the switch, the breakage could be detected.

  A method similar to that of the example except that the line interval of the detection layer was changed to 0.03 mm, the line width was changed to 0.03 mm, and the angle at which the spiral was formed was formed at about 89.9 ° with respect to the direction between the electrode portions. With this, a resistance heating seamless tubular article was obtained.

  Partial breakage of the obtained resistance heating seamless tubular article was detected in the same manner as in Example 1, and it was confirmed that the power supply to the heating layer was cut off. Furthermore, in the case of the configuration of Example 2, detection was possible even with a break of 0.09 mm × 0.09 mm.

  The line resistance of the detection layer was changed to 0.03 mm, the line width was changed to 10 mm, and the angle at which the spiral was formed was formed at about 89.9 ° with respect to the direction between the electrode parts. An exothermic seamless tube was obtained.

  Partial breakage of the obtained resistance heating seamless tubular article was detected in the same manner as in Example 1, and it was confirmed that the power supply to the heating layer was cut off. Furthermore, in the case of the configuration of Example 3, it was possible to detect even a break of 10.06 mm × 10.06 mm.

  The resistance heat generation was performed in the same manner as in Example except that the line interval of the detection layer was changed to 10 mm, the line width was changed to 0.03 mm, and the angle at which the spiral was formed was formed at about 80 ° with respect to the direction between the electrode portions. A tubular article was obtained.

  Partial breakage of the obtained resistance heating seamless tubular article was detected in the same manner as in Example 1, and it was confirmed that the power supply to the heating layer was cut off. Furthermore, in the case of the configuration of Example 4, it was possible to detect even a break of 20.03 mm × 20.03 mm.

A method similar to that of the example except that the line interval of the detection layer was changed to 1.5 mm, the line width was changed to 1.0 mm, and the angle at which the spiral was formed was formed at about 87.5 ° with respect to the direction between the electrode portions. With this, a resistance heating seamless tubular article was obtained.

  Partial breakage of the obtained resistance heating seamless tubular article was detected in the same manner as in Example 1, and it was confirmed that the power supply to the heating layer was cut off. Furthermore, in the case of the configuration of Example 5, it was possible to detect even a break of 4.0 mm × 4.0 mm.

The line spacing of the detection layer was changed to 10 mm and the line width was 10 mm, and the angle at which the spiral was formed was formed at about 57.4 ° with respect to the direction between the electrode portions, and the number of lines of the detection layer was set to two. Except for the above, a resistance heating seamless tubular article was obtained in the same manner as in the example.

  Partial breakage of the obtained resistance heating seamless tubular article was detected in the same manner as in Example 1, and it was confirmed that the power supply to the heating layer was cut off.

  The heating element according to the present invention has a feature that safety can be ensured by quickly detecting a partial breakage or the like occurring in the heating element, thereby cutting off the power supply to the heating element, and has a copier, a laser beam. It can be used as an image fixing device of an image forming apparatus such as a printer and a fixing belt and a fixing tube used in the image fixing device. The heating element may be in the form of a sheet, and can be widely used as a heating unit in addition to an image fixing device of an image forming apparatus such as a copying machine and a laser beam printer, and an application of the image fixing device.

Reference Signs List 100 resistance heating seamless tubular article 110 heating layer 120 electrode (heating layer)
130 Insulating layer 140 Sensing layer 140 'Sensing layer (in case of multiple formation)
150 Elastic layer 160 Release layer 170 Belt support 171 Cylindrical part 172 Belt guide part 180 Electrode (detection layer)
210 Power supply roll 220 Power supply roll (detection layer)
230 AC current 240 DC current 300 Pressure roll 310 Roll body 320 Shaft 400 Image fixing device 600 Excitation relay switch 610 Core

Claims (3)

A heating element in which a heating layer, an insulating layer, and a detection layer are stacked in this order, wherein the detection layer is energized through an electrode portion, is provided in a linear shape in a direction between the electrode portions, and has a line interval of the linear shape. Is formed so as to be 0.03 mm or more and 10 mm or less.   The heating element according to claim 1, wherein the width of the line shape in the detection layer is 0.03 mm or more and 10 mm or less. The detection layer has a shape in which a plurality of turns are spirally or obliquely bent in a direction between the electrode portions, or a shape in which a straight line is bent in a plurality of Z-shapes or a shape in which a plurality of straight lines are bent in a U-shape. The heating element according to claim 1 or 2, wherein