JP2017037154A - Self-heating type fixing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-heating type fixing roller capable of suppressing abnormal heating when a crack is generated on a surface.SOLUTION: The self-heating type fixing roller comprises a cylindrical resistor layer heated by energization and a plurality of energization parts being in contact with the resistor layer and extending in a circumferential direction. The electrical resistivity of the energization parts is smaller than that of the resistor layer. The energization parts are preferably annular. The plurality of energization parts are preferably arranged in the axial direction at an equal interval. The width in the axial direction of the energization parts is preferably fixed. The average width of the plurality of energization parts is preferably 0.3 mm or more and 5 mm or less. The average interval between the plurality of energization parts is preferably 0.5 mm or more and 10 mm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a self-heating type fixing roller.

  In an image forming apparatus such as a copying machine or a laser beam printer, a thermal fixing method is generally employed at the final stage of printing and copying. In this thermal fixing method, unfixed toner is heated and melted by passing an object to be transferred such as printing paper onto which a toner image has been transferred between a fixing roller and a pressure roller in which a heater is disposed. In this method, toner is fixed on a transfer object to form an image.

  A fixing roller having a structure in which a fluororesin layer is formed directly or via another layer on the outer peripheral surface of a cylindrical base material made of polyimide, metal, or the like (the surface in contact with the transfer object) is used. Yes. A material using rubber or the like having excellent elasticity, releasability, wearability, etc. as another layer is sometimes called a fixing sleeve. At the time of printing, it is used inside a cylindrical base material. A heater is provided inside the fixing roller, and heat generated from the heater is conducted to the outer peripheral surface of the fixing roller to heat the toner.

  However, the conventional fixing roller has a disadvantage in that the structure is complicated and the manufacturing process becomes complicated because the heater is disposed inside.

  Therefore, a self-heating type fixing roller has been proposed in which conductive particles are dispersed in a resin layer in the vicinity of the surface of the fixing roller, and the resin layer is a resistor capable of generating heat when energized (see Japanese Patent Application Laid-Open No. 2014-145828). ).

JP 2014-145828 A

  In the self-heating type fixing roller disclosed in the above publication, if a crack occurs on the surface, the current bypasses the crack, and the current density locally increases. In particular, cracks generated on the surface of the self-heating type fixing roller are often formed so as to extend in the circumferential direction, and abnormal heat generation may occur on both sides of the crack in the circumferential direction.

  The present invention has been made based on the above-described circumstances, and an object thereof is to provide a self-heating type fixing roller capable of suppressing abnormal heat generation when a crack occurs on the surface.

  A self-heating type fixing roller according to an aspect of the present invention made to solve the above-described problem is a self-heating type fixing roller including a cylindrical resistor layer that generates heat when energized, and is in contact with the resistor layer. A plurality of energization portions extending in the circumferential direction are provided, and the energization portion has an electrical resistivity smaller than that of the resistor layer.

  The self-heating type fixing roller according to one embodiment of the present invention can suppress abnormal heat generation when a crack occurs on the surface.

FIG. 1 is a schematic perspective view showing a self-heating type fixing roller according to an embodiment of the present invention. FIG. 2 is a schematic axial sectional view of the self-heating type fixing roller of FIG. FIG. 3 is a schematic axial sectional view of a self-heating type fixing roller according to an embodiment different from FIG. FIG. 4 is a schematic axial cross-sectional view of a self-heating type fixing roller according to an embodiment different from FIGS. 1 and 3. FIG. 5 is a schematic axial sectional view of a self-heating type fixing roller according to an embodiment different from those of FIGS. 1, 3, and 4. FIG. 6 is a schematic axial sectional view of a self-heating type fixing roller according to an embodiment different from those in FIGS. 1 and 3 to 5. FIG. 7 is a schematic axial sectional view of a self-heating type fixing roller according to an embodiment different from those in FIGS. 1 and 3 to 6.

[Description of Embodiment of the Present Invention]
A self-heating type fixing roller according to an aspect of the present invention is a self-heating type fixing roller including a cylindrical resistor layer that generates heat when energized, and is in contact with the resistor layer and extends in a circumferential direction. An energization part is provided, and the energization part has a smaller electrical resistivity than the resistor layer.

  The self-heating type fixing roller includes a current-carrying portion having an electrical resistivity (volume resistivity) smaller than that of the resistor layer, so that even if a crack occurs in the resistor layer, the current-carrying portion close to the crack is directed to the crack. Is dispersed in the circumferential direction with a small resistance loss, so that the abnormal heat generation of the resistor layer can be suppressed.

  The conducting part may be annular. Thus, since the said conduction | electrical_connection part is cyclic | annular, since the electric current which goes to a crack can be disperse | distributed to a perimeter, abnormal heat_generation | fever can be suppressed more reliably.

  The plurality of conducting portions may be arranged at equal intervals in the axial direction. As described above, since the plurality of conductive portions are arranged at equal intervals in the axial direction, the effect of suppressing abnormal heat generation can be made relatively uniform in the axial direction.

  The width in the axial direction of the conducting portion may be constant. As described above, since the axial width of the conductive portion is constant, the effect of suppressing abnormal heat generation can be made relatively uniform in the axial direction.

  The average width of the plurality of conductive portions is preferably 0.3 mm or more and 5 mm. Thus, when the average width of the plurality of conducting portions is within the above range, abnormal heat generation can be more reliably suppressed, and temperature unevenness in the axial direction can be suppressed.

[Details of the embodiment of the present invention]
Hereinafter, each embodiment of the self-heating type fixing roller according to the present invention will be described in detail with reference to the drawings.

[First embodiment]
The self-heating type fixing roller shown in FIGS. 1 and 2 includes a cylindrical resistor layer 1 that generates heat when energized, and a plurality of energizing portions 2 that are in contact with the resistor layer 1 and extend in the circumferential direction. The plurality of energization portions 2 have a smaller electrical resistivity (volume resistivity) than the resistor layer 1.

  In the self-heating type fixing roller, even if a crack occurs in the resistor layer 1, the current-carrying portions 2 on both sides in the axial direction of the crack disperse the current toward the crack in the circumferential direction with a small resistance loss (low heat generation). Abnormal heat generation of the body layer 1 can be suppressed. That is, the self-heating type fixing roller can suppress abnormal heat generation in a region of the resistor layer 1 where the energization portions 2 exist on both sides in the axial direction.

  The self-heating type fixing roller includes a columnar core 3 and a cylindrical heat insulating layer 4 laminated on the outer peripheral surface of the core 3. The resistor layer 1 and the energizing portion 2 are laminated on the outer peripheral surface of the heat insulating layer 4.

<Resistor layer>
The resistor layer 1 has a plurality of slits extending in the circumferential direction, and the energization part 2 is disposed in the slits. Thereby, the energization part 2 is in electrical contact with the regions on both sides in the axial direction of the resistor layer 1. By disposing the current-carrying part 2 in the slit in this way, the current-carrying part 2 can be formed flush with the resistor layer 1, so that it becomes easy to flatten the surface of the self-heating type fixing roller. .

  The material for forming the resistor layer 1 may be any material that can pass an electric current and generate heat due to resistance loss, but preferably a resin matrix and a plurality of conductive particles included in the resin matrix. A resistor having the following is used. Resistors in which a plurality of conductive particles are dispersed in a resin matrix can be selected relatively easily from those having the desired moldability, heat generation and flexibility. High performance and low price can be achieved easily.

  Specifically, the resistor layer 1 can be formed by laminating a resistor in which a plurality of conductive particles are dispersed in a resin matrix on the outer peripheral surface of the heat insulating layer 4 by a method such as coating or printing. As the coating method, for example, a dispenser, a coater or the like can be used. Moreover, as the printing method, for example, screen printing, ink jet printing, or the like can be used. The resistor layer 1 may be formed by extrusion.

  The main component of the resin matrix of the resistor layer 1 includes a heat-resistant synthetic resin or rubber, and among them, a heat-resistant resin is preferable. Examples of the heat resistant resin include polyimide and polyamide, and polyimide having excellent heat resistance and mechanical strength is particularly preferable. As the heat resistant rubber, silicone rubber, fluororubber, or a mixture thereof can be used. The “main component” means a component having the largest mass content.

  As the conductive particles, known particles can be used, and examples thereof include metal powders such as gold and nickel, and resin particles subjected to metal plating, such as carbon powders such as carbon black and carbon nanotubes. Among these, from the viewpoint of heat resistance and electrical conductivity, the conductive particles preferably include carbon powder, and more preferably a mixture of metal powder and carbon powder. The metal powder is preferably nickel powder.

  When the conductive particles are a mixture of metal powder and carbon powder, the upper limit of the ratio of the carbon powder in the conductive particles of the resistor layer 1 is preferably 97% by volume, and more preferably 95% by volume. On the other hand, the lower limit of the ratio of the carbon powder in the conductive particles of the resistor layer 1 is preferably 30% by volume, and more preferably 50% by volume. When the ratio of the carbon powder in the conductive particles of the resistor layer 1 exceeds the upper limit, the metal powder may not be uniformly dispersed, and it may not be easy to make the electric resistance of the resistor layer 1 uniform. On the contrary, when the ratio of the carbon powder in the conductive particles of the resistor layer 1 is less than the lower limit, the electric resistance of the resistor layer 1 is greatly reduced by the conductive particles, and the electric resistance of the resistor layer 1 is adjusted. May not be easy.

  Moreover, it is preferable that the electroconductive particle in the resistor layer 1 is acicular. Since the conductive particles are needle-shaped, the electrical conductivity of the resistor layer 1 is reduced in the orientation direction of the conductive particles and perpendicular to the orientation direction of the conductive particles. Can be larger in the direction. Thereby, the electrical resistivity in the axial direction of the resistor layer 1 can be made smaller than the electrical resistivity in the circumferential direction. In this way, since the current flows stably in the axial direction, the thermal characteristics are stabilized.

  The lower limit of the aspect ratio of the conductive particles is preferably 1.5 and more preferably 2.0. On the other hand, the upper limit of the aspect ratio of the conductive particles is preferably 1000, and more preferably 100. When the aspect ratio of the conductive particles is less than the above lower limit, there is a possibility that a difference in electrical resistivity cannot be provided between the axial direction and the circumferential direction. On the other hand, when the aspect ratio of the conductive particles exceeds the above upper limit, the coating of the resistor layer 1 may not be easy.

  Examples of the acicular carbon powder include carbon nanotubes (hereinafter sometimes referred to as “CNT”). CNT is nano-sized cylindrical carbon. CNTs generally have a specific gravity of about 2.0 and an aspect ratio (a ratio of length to diameter) of 50 or more and 1000 or less. In addition, as the CNT, a single-wall type and a multi-wall type are typical. The multi-layered CNT has a structure in which cylindrical carbon materials are overlapped in a concentric manner. As a method for producing CNT, a known method can be used. However, a vapor phase growth method that can easily control the diameter of CNT and is excellent in mass productivity is preferable.

  As an upper limit of the average diameter of CNT, 500 nm is preferable and 300 nm is more preferable. On the other hand, the lower limit of the average diameter is preferably 100 nm. When the said average diameter exceeds the said upper limit, there exists a possibility that the softness | flexibility of the resistor layer 1 and the smoothness of the surface may fall. On the other hand, when the average diameter is less than the lower limit, the dispersibility of CNTs may be reduced and the mechanical strength of the resistor layer 1 may be reduced, or the productivity of CNTs may be reduced. In addition, the average diameter of CNT is the average value of the short axis diameter of CNT measured by observation with a laser scattering method or a scanning electron microscope, for example.

  The upper limit of the average CNT length is preferably 50 μm, more preferably 30 μm, and even more preferably 20 μm. On the other hand, the lower limit of the average length is preferably 1 μm. When the average length exceeds the above upper limit, the dispersibility of CNTs may be reduced, the mechanical strength of the resistor layer 1 may be reduced, and the smoothness of the surface of the resistor layer 1 may be reduced. On the other hand, when the average length is less than the lower limit, the mechanical strength such as elongation at break of the resistor layer 1 may be insufficient. In addition, the average length of CNT is the average value of the length of CNT measured, for example by observation with a laser scattering method or a scanning electron microscope.

  In addition, as the carbon powder having a shape other than the needle shape, for example, shell-like carbon particles can be used. By using such shell-like carbon particles, the change in the electric resistance of the resistor layer 1 with respect to the added amount becomes gentle, and the electric resistance of the resistor layer 1 can be easily adjusted.

  Moreover, it does not specifically limit as an acicular metal powder, For example, an acicular nickel powder etc. are mentioned.

  The upper limit of the content of the conductive particles in the resistor layer 1 is preferably 60% by volume, more preferably 55% by volume, and still more preferably 50% by volume. On the other hand, as a minimum of the above-mentioned content, 5 volume% is preferred, 10 volume% is more preferred, and 15 volume% is still more preferred. When the said content exceeds the said upper limit, there exists a possibility that the heat resistance of the resistor layer 1, mechanical strength, etc. may fall. On the contrary, when the content is less than the lower limit, the resistance of the resistor layer 1 may be difficult to be within a desired range.

  The upper limit of the average thickness of the resistor layer 1 is preferably 300 μm, more preferably 250 μm, and even more preferably 200 μm. On the other hand, the lower limit of the average thickness is preferably 5 μm, more preferably 10 μm, and even more preferably 30 μm. When the average thickness exceeds the upper limit, the manufacturing cost of the self-heating type fixing roller may increase. On the other hand, when the average thickness is less than the lower limit, the resistor layer 1 may be easily damaged by heat or impact.

  The upper limit of the electrical resistance (including the energization part 2) between the axial ends of the resistor layer 1 is preferably 100Ω, more preferably 80Ω, and even more preferably 60Ω. On the other hand, the lower limit of the electrical resistance between both ends of the resistor layer 1 is preferably 5Ω, more preferably 7.5Ω, and even more preferably 10Ω. When the resistance exceeds the upper limit, the voltage required for increasing the temperature of the resistor layer 1 increases, and the power supply device for driving the self-heating type fixing roller may be unnecessarily expensive. On the other hand, if the resistance is less than the lower limit, the current required for increasing the temperature of the resistor layer 1 becomes large, and the power supply device for driving the self-heating fixing roller may be unnecessarily expensive. There is.

  Further, the upper limit of the electrical resistance per unit length in the axial direction of the resistor layer 1 is preferably 1000 Ω / m, more preferably 800 Ω / m, and even more preferably 600 Ω / m. On the other hand, the lower limit of the electrical resistance per unit length in the axial direction of the resistor layer 1 is preferably 0.01 Ω / m, more preferably 0.1 Ω / m, and even more preferably 1 Ω / m. When the length resistivity exceeds the upper limit, the electrical resistance of the resistor layer 1 may be excessively increased. Conversely, when the length resistivity is less than the lower limit, the electrical resistance of the resistor layer 1 may be too small.

  Furthermore, the resistor layer 1 may include an insulating filler. By including the insulating filler, the electrical contact between the conductive particles can be limited, and the electrical resistance of the resistor layer 1 can be adjusted relatively easily.

  As a material of such an insulating filler, any material having an insulating property may be used, but titanium oxide, metal silicon, magnesium oxide, magnesium carbonate, magnesium hydroxide, silicon oxide, alumina, boron nitride, which has high thermal conductivity, An inorganic filler such as aluminum nitride is preferably used.

<Energizing part>
The plurality of energization units 2 are provided extending in the circumferential direction, and suppress abnormal heat generation of the resistor layer 1 in a region sandwiched between the two energization units 2. The shape of each energization portion 2 in the axial direction of the self-heating type fixing roller can be, for example, a C-shape, an arc shape, an annular shape, etc., but is in contact with the resistor layer 1 over the entire circumference. It is preferable to be formed in a ring shape. Thus, since the conduction | electrical_connection part 2 is cyclic | annular, since the electric current which goes to the crack formed in the resistor layer 1 can be disperse | distributed to a perimeter, abnormal heat_generation | fever can be suppressed more reliably.

  The material for forming the energizing portion 2 may be any material as long as it has a smaller electrical resistivity that allows current to flow than the resistor layer 1, but preferably a resin matrix and a plurality of conductive materials included in the resin matrix. A conductor having particles is used. Since a conductive material in which a plurality of conductive particles are dispersed in a resin matrix can be selected with a relatively easy moldability, conductivity and flexibility, the self-heating type fixing roller is compared. Can be manufactured easily and inexpensively.

  Thus, the energization part 2 can be formed by methods, such as coating and printing, by making the energization part 2 contain several electroconductive particle in a resin matrix. As the coating method, for example, a dispenser, a coater or the like can be used. Moreover, as the printing method, for example, screen printing, ink jet printing, or the like can be used.

  As a conductor containing a plurality of conductive particles in such a resin matrix, for example, a conductive paste cured can be used. Moreover, it is preferable that the resin matrix of the energization part 2 is mainly composed of a resin having the same or high affinity as the resin matrix of the resistor layer 1. Thereby, the mechanical adhesion between the resistor layer 1 and the energizing portion 2 is improved, and the electrical contact between the resistor layer 1 and the energizing portion 2 becomes more reliable.

  The plurality of energization units 2 are preferably arranged at equal intervals in the axial direction. By disposing the plurality of energizing portions 2 at equal intervals, the resistor layer 1 can generate heat relatively uniformly in the axial direction, and the effect of suppressing abnormal heat generation can be made relatively uniform in the axial direction. .

  As a minimum of an average interval of a plurality of energization parts 2, 0.5 mm is preferred and 1 mm is more preferred. On the other hand, it is preferable that the plurality of current-carrying parts 2 are formed side by side at equal intervals in the axial direction. The upper limit of the average interval between the plurality of current-carrying parts 2 is preferably 10 mm, and more preferably 7 mm. When the average space | interval of the several electricity supply part 2 is less than the said minimum, there exists a possibility that between the electricity supply parts 2 may short-circuit, and there exists a possibility that the emitted-heat amount of the resistor layer 1 may become inadequate. On the contrary, when the average interval between the plurality of current-carrying parts 2 exceeds the upper limit, abnormal heat generation may not be sufficiently suppressed when the resistor layer 1 is cracked.

  The current of the resistor layer 1 tends to be concentrated on the portion of the energizing portion 2 that protrudes in the axial direction. For this reason, it is preferable that the energizing portions 2 each have a constant width in the axial direction so that current can flow relatively uniformly through the resistor layer 1.

  As a minimum of the average width of a plurality of conduction parts 2, 0.3 mm is preferred and 0.5 mm is more preferred. On the other hand, the upper limit of the average width of the plurality of conducting portions 2 is preferably 5 mm, and more preferably 3 mm. When the average width of the plurality of conducting portions 2 is less than the lower limit, current cannot be sufficiently dispersed in the circumferential direction, and abnormal heat generation of the resistor layer 1 due to cracks may not be sufficiently suppressed. Conversely, if the average width of the number of conducting portions 2 exceeds the above upper limit, the variation in the circumferential direction of the surface temperature of the self-heating type fixing roller may increase, or the amount of heat generated by the self-heating type fixing roller may be insufficient. There is a risk of becoming.

  The lower limit of the ratio of the electrical resistivity (volume resistivity) of the conducting portion 2 to the electrical resistivity of the resistor layer 1 is not particularly limited. On the other hand, the upper limit of the ratio of the electrical resistivity of the conductive portion 2 to the electrical resistivity of the resistor layer 1 is preferably 0.5 times, and more preferably 0.1 times. When the ratio of the electrical resistivity of the conductive portion 2 to the electrical resistivity of the resistor layer 1 exceeds the upper limit, the current flowing through the resistor layer 1 cannot be sufficiently dispersed in the circumferential direction, and the resistor layer is caused by cracks. 1 abnormal heat generation may not be sufficiently suppressed.

<Core>
The core 3 extends in the axial direction at the center of the self-heating type fixing roller. The core 3 may be hollow or solid.

  For the core 3, a metal such as aluminum, aluminum alloy, iron, stainless steel, or a heat resistant resin such as polyimide or polyamide can be used. Among the heat resistant resins, a polyimide having excellent moldability and excellent heat resistance and mechanical strength is preferable.

  The average outer diameter of the cored bar 3 can be, for example, 5 mm or more and 40 mm or less. Moreover, when the cored bar 3 is hollow, the average thickness of the cored bar 3 can be, for example, 10 μm or more and 40 mm or less. The axial length of the cored bar 3 can be, for example, 100 mm or more and 500 mm or less.

<Insulation layer>
The heat insulation layer 4 suppresses the heat generated by the resistor layer 1 from escaping to the cored bar 3 side, and improves the energy efficiency of the self-heating type fixing roller. The heat insulating layer 4 preferably has a matrix mainly composed of a synthetic resin or rubber and a plurality of pores contained in the matrix. Furthermore, it is preferable that this heat insulation layer 4 has elasticity.

  The rubber used as the main component of the matrix of the heat insulating layer 4 is not particularly limited as long as it has heat resistance, but preferably has elasticity, and rubber (heat resistant rubber) having excellent heat resistance is particularly preferable. As this heat resistant rubber, silicone rubber, fluoro rubber, or a mixture thereof can be suitably used.

  Examples of the silicone rubber include dimethyl silicone rubber, fluorosilicone rubber, and methylphenyl silicone rubber. Examples of the fluororubber include vinylidene fluoride rubber, tetrafluoroethylene-propylene rubber, tetrafluoroethylene-perfluoromethyl vinyl ether rubber, and the like.

  Examples of the synthetic resin include phenol resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (urea resin, UF), unsaturated polyester resin (UP), alkyd resin, polyurethane (PUR). ), Thermosetting polyimide (PI), polyethylene (PE), high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polychlorinated Vinylidene, polystyrene (PS), polyvinyl acetate (PVAc), acrylonitrile butadiene styrene resin (ABS), acrylonitrile styrene resin (AS), polymethyl methacrylate (PMMA), polyamide (PA), polyacetal (POM), polycarbonate (PC) , Sex polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and cyclic polyolefin (COP) and the like.

  The pores in the matrix of the heat insulating layer 4 can be formed by a foaming agent, a hollow filler, or the like. Examples of the hollow filler that can be used include organic microballoons and hollow glass beads.

  As said foaming agent, it decomposes | disassembles by heating and generate | occur | produces, for example, nitrogen gas, a carbon dioxide gas, carbon monoxide, ammonia gas etc., An organic foaming agent or an inorganic foaming agent can be used.

  Examples of the organic blowing agent include azo blowing agents such as azodicarbonamide (A.D.C.A) and azobisisobutyronitrile (A.I.B.N), such as dinitrosopentamethylenetetramine (D P.T), N, N′dinitroso-N, N′-dimethyl terephthalamide (DNDMTA), and the like, for example, P-toluenesulfonyl hydrazide (T.S. H), P, P-oxybisbenzenesulfonyl hydrazide (OBSH), benzenesulfonyl hydrazide (BSH), and others, and trihydrazinotriazine (TH T), acetone-P-sulfonylhydrazone and the like are exemplified, and these can be used alone or in combination of two or more.

  Examples of the inorganic foaming agent include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, sodium borohydride, sodium boron hydride, silicon oxyhydride and the like. In general, an inorganic foaming agent has a slower gas generation rate than an organic foaming agent, and adjustment of gas generation is difficult. Therefore, an organic foaming agent is preferable as the chemical foaming agent.

  The organic microballoon is a kind of hollow microsphere (Microsphere), for example, a thermosetting resin such as phenol resin, a thermoplastic resin such as polyvinylidene chloride, and a hollow formed by an organic polymer material such as rubber. The spherical fine particles. When the heat insulation layer 4 contains an organic microballoon, the flexibility, heat resistance and dimensional stability of the heat insulation layer 4 are improved. Since this organic microballoon has a spherical shape, stress anisotropy hardly occurs even if it is included in the composition forming the heat insulating layer 4. Therefore, the organic microballoon is difficult to reduce the hardness and the heat insulation uniformity of the heat insulating layer 4. Moreover, the heat resistance of the heat insulation layer 4 improves more by using the heat resistant organic microballoon containing thermosetting resins, such as a phenol resin, as an organic microballoon. In addition, a commercial item can be used as said organic microballoon.

  The average diameter of the organic microballoon is usually several μm or more and several hundreds μm or less, preferably 5 μm or more and 200 μm or less.

  As an upper limit of the porosity of the heat insulation layer 4, 60% is preferable, 50% is more preferable, and 45% is further more preferable. On the other hand, the lower limit of the porosity of the heat insulating layer 4 is preferably 5%, more preferably 10%, and even more preferably 15%. When the porosity of the heat insulation layer 4 exceeds the said upper limit, there exists a possibility that the intensity | strength of the heat insulation layer 4 may become inadequate. On the contrary, when the porosity of the heat insulation layer 4 is less than the said minimum, there exists a possibility that the heat insulation of the heat insulation layer 4 may become inadequate. The porosity is a value measured as an area ratio when a cross section is observed with a microscope.

  As an upper limit of the average thickness of the heat insulation layer 4, 500 mm is preferable and 200 mm is more preferable. On the other hand, the lower limit of the average thickness is preferably 20 μm, and more preferably 100 μm. When the average thickness exceeds the upper limit, the size of the self-heating type fixing roller may increase unnecessarily. On the contrary, when the average thickness is less than the lower limit, the heat insulating property of the heat insulating layer 4 becomes insufficient, and the energy efficiency of the self-heating type fixing roller may be lowered.

  It is preferable that the heat insulation layer 4 and the resistor layer 1 are joined directly or via another layer. In this way, the heat insulating layer 4 and the resistor layer 1 are joined, so that wear due to friction between the inner peripheral surface of the resistor layer 1 (surface on the core metal 3 side) and the other layers is caused. And the durability of the self-heating type fixing roller is improved. As a specific example, the bonding strength between the heat insulating layer 4 and the current-carrying part 2 and the resistor layer 1 can be improved by laminating a primer layer between the heat-insulating layer 4 and the current-carrying part 2 and the resistor layer 1. .

<Advantages>
The self-heating type fixing roller includes a plurality of current-carrying parts 2 having an electrical resistivity smaller than that of the resistor layer 1, so that even if a crack occurs in the resistor layer 1, the current-carrying parts 2 on both sides in the axial direction of the crack As a result, the abnormal heat generation of the resistor layer 1 can be suppressed.

[Second Embodiment]
The self-heating type fixing roller of FIG. 3 includes a cylindrical resistor layer 1a that generates heat when energized, and a plurality of energizing portions 2a that are in contact with the resistor layer 1a and extend in the circumferential direction. The plurality of energization portions 2a have an electrical resistivity smaller than that of the resistor layer 1a.

  In the self-heating type fixing roller, the plurality of energizing portions 2a are stacked on the outer peripheral surface of the resistor layer 1a. As described above, since the plurality of energization parts 2a are laminated on the outer peripheral surface of the resistor layer 1a, the resistor layer 1a and the energization part 2a can be easily formed by a relatively simple method such as coating or printing. Can be formed. Moreover, it is also possible to adhere | attach the electricity supply part 2a with a conductive adhesive on the outer peripheral surface of the resistor layer 1a.

  The self-heating type fixing roller includes a columnar core 3 and a cylindrical heat insulating layer 4 laminated on the outer peripheral surface of the core 3. The resistor layer 1 a is laminated on the outer peripheral surface of the heat insulating layer 4.

  Further, the self-heating type fixing roller includes a release layer 5 that is laminated so as to cover the outer peripheral surfaces of the resistor layer 1a and the plurality of energization portions 2a.

  The metal core 3 and the heat insulating layer 4 in the self-heating type fixing roller of FIG. 3 can be the same as the metal core 3 and the heat insulating layer 4 in the self-heating type fixing roller of FIGS.

<Resistor layer>
The resistor layer 1 a is laminated on the entire outer peripheral surface of the heat insulating layer 4 with a substantially constant thickness. The material and average thickness of the resistor layer 1a in the self-heating type fixing roller of FIG. 3 can be the same as the material and average thickness of the resistor layer 1 in the self-heating type fixing roller of FIGS.

<Energizing part>
In the self-heating type fixing roller of FIG. 3, the material forming the energization part 2a, the average interval, the average width, the electrical resistivity, and the electric resistance per unit length in the circumferential direction of the energization part 2a are shown in FIGS. In the self-heating type fixing roller, the material for forming the energization portion 2, the average interval, the average width, the electrical resistivity, and the electrical resistance per unit length in the circumferential direction of the energization portion 2 can be used.

  In addition, the lower limit of the average width of the energizing portions 2a in the self-heating type fixing roller of FIG. 3 is preferably 1 times the average thickness of the resistor layer 1a, and more preferably 2 times the average thickness of the resistor layer 1a. When the ratio of the average width of the current-carrying part 2a to the average thickness of the resistor layer 1a is less than the lower limit, the current flowing through the inner peripheral surface of the resistor layer 1a cannot be sufficiently collected in the current-carrying part 2a. There is a possibility that the abnormal heat generation of the resistor layer 1a cannot be sufficiently suppressed.

<Release layer>
The release layer 5 is a layer that is laminated on the outer peripheral surface of the heat insulating layer 4 and is in contact with the toner. The release layer 5 prevents the toner from adhering to the self-heating type fixing roller and promotes peeling of the recording paper.

  The release layer 5 is formed from a resin composition. The resin composition forming the release layer 5 may be filled between the plurality of current-carrying parts 2a.

  As a main component of the resin composition forming the release layer 5, for example, a thermoplastic resin and a thermosetting resin can be used.

  Examples of the thermoplastic resin include vinyl resin, polyester, polyolefin, acrylic resin, fluorine resin, epoxy resin, phenol resin, urea resin, and the like. Among these, a fluororesin excellent in releasability, flexibility and heat resistance is preferable. These resins may be used alone or in combination of two or more.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (EFP), and tetrafluoroethylene-6 Examples thereof include a fluorinated propylene copolymer (FEP). Among these, PFA or PTFE having a small molecular weight and excellent releasability is preferable.

  The release layer 5 may contain an additive such as a heat conductive filler. When the release layer 5 contains a heat conductive filler, the heat of the resistor layer 1a can be efficiently transmitted to the toner, and variations in the temperature of the surface of the self-heating type fixing roller can be suppressed.

  Examples of the heat conductive filler include metals, ceramics, boron nitride, carbon nanotubes, alumina, silicon carbide, and the like.

The release layer 5 preferably has an insulating property. Specifically, the lower limit of the electrical resistance per unit length in the axial direction of the release layer 5 is preferably 10 ¹⁴ Ω / m. If the length resistivity of the release layer 5 is less than the above lower limit, the resistor layer 1a leaks through the release layer 5 and the heat generation of the resistor layer 1a is likely to be insufficient. There is a risk of equipment failure.

  The upper limit of the average thickness of the release layer 5 is preferably 50 μm and more preferably 35 μm. On the other hand, the lower limit of the average thickness is preferably 1 μm and more preferably 5 μm. When the average thickness exceeds the upper limit, the size of the self-heating fixing roller may be unnecessarily increased, or the thermal efficiency of the self-heating fixing roller may be reduced. On the other hand, when the average thickness is less than the lower limit, the strength of the release layer 5 may be insufficient.

  The release layer 5 may be bonded to the resistor layer 1a or may be rotated independently without being bonded, but is preferably bonded. As described above, the release layer 5 and the resistor layer 1a are bonded to each other so that the inner peripheral surface of the release layer 5 (the surface in contact with the resistor layer 1a) is worn by friction with the resistor layer 1a. And the durability of the self-heating fixing roller is improved. The bonding method of the release layer 5 and the resistor layer 1a is not particularly limited, and a method of bonding simultaneously with the formation of the release layer 5 or the resistor layer 1a, the release layer 5 and the resistor layer 1a are formed. The method of joining later is mentioned. In addition to these methods, the release layer 5 and the resistor layer 1a can be bonded more firmly by combining the main components of the release layer 5 and the resistor layer 1a with a high affinity.

  As a method of bonding after forming the release layer 5 and the resistor layer 1a, for example, a method of bonding the release layer 5 and the resistor layer 1a with an adhesive, a resistor layer 1a of the release layer 5 is laminated. A method of performing a surface treatment such as a plasma treatment on the surface to be processed, and when the main component of the release layer 5 is a fluororesin, for example, by heating, irradiation of ionizing radiation, application of a coupling agent, etc. Examples include a method of chemically bonding the resistor layer 1a.

<Advantages>
In the self-heating type fixing roller, even if a crack occurs in the resistor layer 1a, the current-carrying portions 2a on both sides in the axial direction of the crack disperse the current toward the crack in the circumferential direction with a small resistance loss (low heat generation). Abnormal heat generation of the body layer 1a can be suppressed.

[Third embodiment]
The self-heating type fixing roller of FIG. 4 includes a cylindrical resistor layer 1b that generates heat when energized, and a plurality of energizing portions 2b that are in contact with the resistor layer 1b and extend in the circumferential direction. The plurality of energization portions 2b have a lower electrical resistivity than the resistor layer 1b.

  The self-heating type fixing roller includes a columnar core 3 and a cylindrical heat insulating layer 4 laminated on the outer peripheral surface of the core 3. The resistor layer 1 b is laminated on the outer peripheral surface of the heat insulating layer 4.

  The core metal 3 and the heat insulating layer 4 in the self-heating type fixing roller of FIG. 4 can be the same as the core metal 3 and the heat insulating layer 4 in the self-heating type fixing roller of FIGS.

  In the self-heating type fixing roller, the plurality of energization portions 2b are embedded in the resistor layer 1b. For example, when the resistor layer 1b is applied to the outer peripheral surface of the heat insulating layer 4, the plurality of energization portions 2b can be embedded in the resistor layer 1b by arranging an annular member. Alternatively, the resistor layer 1b may be divided into a plurality of layers and formed by coating, and a step of applying a material for forming the energization portion 2b may be provided between the plurality of coating steps.

<Resistor layer>
The material and average thickness of the resistor layer 1b in the self-heating type fixing roller of FIG. 3 can be the same as the material and average thickness of the resistor layer 1 in the self-heating type fixing roller of FIGS.

<Energizing part>
In the self-heating type fixing roller of FIG. 4, the material forming the energization part 2b, the average interval, the average width, the electrical resistivity, and the electrical resistance per unit length in the circumferential direction of the energization part 2b are shown in FIGS. In the self-heating type fixing roller, the material for forming the energization portion 2, the average interval, the average width, the electrical resistivity, and the electrical resistance per unit length in the circumferential direction of the energization portion 2 can be used.

<Advantages>
In the self-heating type fixing roller, even if a crack occurs in the resistor layer 1b, the current-carrying portions 2b on both sides in the axial direction of the crack disperse the current toward the crack in the circumferential direction with a small resistance loss (low heat generation). Abnormal heat generation of the body layer 1b can be suppressed.

[Fourth embodiment]
The self-heating type fixing roller of FIG. 5 includes a cylindrical resistor layer 1c that generates heat when energized, and a plurality of energizing portions 2c that are in contact with the resistor layer 1c and extend in the circumferential direction. The plurality of energization portions 2c have a lower electrical resistivity than the resistor layer 1c.

  The self-heating type fixing roller includes a columnar core 3 and a cylindrical heat insulating layer 4 laminated on the outer peripheral surface of the core 3. The resistor layer 1 c is laminated on the outer peripheral surface of the heat insulating layer 4.

  The core metal 3 and the heat insulating layer 4 in the self-heating type fixing roller of FIG. 5 can be the same as the core metal 3 and the heat insulating layer 4 in the self-heating type fixing roller of FIGS.

  In the self-heating type fixing roller, the plurality of energizing portions 2c are stacked on the inner peripheral surface of the resistor layer 1c. The plurality of energization portions 2c are arranged so as to be embedded in the heat insulating layer 4, and the outer peripheral surface is in contact with the resistor layer 1c.

  In the self-heating type fixing roller, a plurality of energizing portions 2c are formed on the inner peripheral surface of the resistor layer 1c formed in a cylindrical shape by, for example, coating, and a core is formed inside the resistor layer 1c in which the energizing portions 2c are formed. It can be formed by filling and foaming the material forming the heat insulating layer 4 with the gold 3 disposed.

<Resistor layer>
The material and average thickness of the resistor layer 1c in the self-heating type fixing roller of FIG. 5 can be the same as the material and average thickness of the resistor layer 1 in the self-heating type fixing roller of FIGS.

<Energizing part>
The material for forming the energizing portion 2c in the self-heating type fixing roller of FIG. 5, the average interval, the average width, the electrical resistivity, and the electrical resistance per unit length in the circumferential direction of the energizing portion 2c are shown in FIGS. In the self-heating type fixing roller, the material for forming the energization portion 2, the average interval, the average width, the electrical resistivity, and the electrical resistance per unit length in the circumferential direction of the energization portion 2 can be used.

<Advantages>
In the self-heating type fixing roller, even if a crack occurs in the resistor layer 1c, the energizing portions 2c on both sides in the axial direction of the crack disperse the current toward the crack in the circumferential direction with a small resistance loss (low heat generation). Abnormal heat generation of the body layer 1c can be suppressed.

[Fifth embodiment]
The self-heating type fixing roller of FIG. 6 includes an endless belt-like base material 6, a cylindrical resistor layer 1 that generates heat when energized, and a plurality of energizing portions that are in contact with the resistor layer 1 and extend in the circumferential direction. 2 is provided. The resistor layer 1 and the energizing portion 2 are laminated on the outer peripheral surface of the base material 6.

  The resistor layer 1 and the energization unit 2 in the self-heating type fixing roller in FIG. 6 are the same as the resistor layer 1 and the energization unit 2 in the self-heating type fixing roller in FIG. A duplicate description will be omitted.

  The self-heating type fixing roller is also called a fixing film, and a member that presses the self-heating type fixing roller against the recording paper is used inside the fixing device.

<Base material>
As the substrate 6, for example, a metal such as stainless steel or a resin such as polyimide is used. The base material 6 preferably has an insulating property. When a conductive material such as a metal is used, at least the resistor layer 1 is insulated.

  As a minimum of average thickness of substrate 6, 10 micrometers is preferred and 20 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the substrate 6 is preferably 100 μm, and more preferably 80 μm. If the average thickness of the substrate 6 is less than the lower limit, the strength of the self-heating type fixing roller may be insufficient. On the contrary, when the average thickness of the substrate 6 exceeds the upper limit, the flexibility of the self-heating type fixing roller may be insufficient.

<Advantages>
In the self-heating type fixing roller, even if a crack occurs in the resistor layer 1, the current-carrying portions 2 on both sides in the axial direction of the crack disperse the current toward the crack in the circumferential direction with a small resistance loss. Abnormal heat generation can be suppressed.

[Sixth embodiment]
The self-heating type fixing roller of FIG. 7 includes an endless belt-like base material 6a, a cylindrical resistor layer 1 that generates heat when energized, and a plurality of energizing portions that are in contact with the resistor layer 1 and extend in the circumferential direction. 2 is provided. The resistor layer 1 and the energizing portion 2 are laminated on the inner peripheral surface of the base material 6a.

  Since the resistor layer 1 and the energization unit 2 in the self-heating type fixing roller of FIG. 7 are the same as the resistor layer 1 and the energization unit 2 in the self-heating type fixing roller of FIG. A duplicate description will be omitted.

<Base material>
For example, a metal such as stainless steel or a resin such as polyimide is used as the substrate 6a. The base material 6a preferably has an insulating property. When a conductive material such as a metal is used, at least the resistor layer 1 and the energizing portion 2 are insulated.

  Further, in the self-heating type fixing roller, the heat of the resistor layer 1 is transmitted to the toner through the base material 6a. Therefore, it is preferable that the base material 6a has a relatively high thermal conductivity. For this reason, when base material 6a is formed from resin, it is preferred that a heat conductive filler is included.

  The average thickness of the base material 6a in the self-heating type fixing roller in FIG. 7 can be the same as that of the base material 6 in the self-heating type fixing roller in FIG.

<Advantages>
In the self-heating type fixing roller, even if a crack occurs in the resistor layer 1, the current-carrying portions 2 on both sides in the axial direction of the crack disperse the current toward the crack in the circumferential direction with a small resistance loss. Abnormal heat generation can be suppressed.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  The self-heating type fixing roller only needs to include the resistor layer and the plurality of energizing portions as described above, and the structure other than the resistor layer and the energizing portion is arbitrary as long as the effect of the invention is exerted. For example, an adhesive layer or a primer layer may be provided to improve the adhesive strength between layers. Further, the layer described above in the self-heating type fixing roller may have a multilayer structure. A release layer that promotes peeling of the recording paper is also optional.

  In the self-heating type fixing roller, the resistor layer may be formed of a woven fabric or a non-woven fabric containing conductive fibers.

  The self-heating type fixing roller may be formed so as to be in contact with both end portions in the axial direction of the resistor layer, and may have an annular equipotential electrode that disperses a current applied from a power source in the circumferential direction.

  The self-heating type fixing roller of the present invention is suitably used for a fixing device of an electrophotographic image forming apparatus.

1, 1a, 1b, 1c Resistor layers 2, 2a, 2b, 2c Current-carrying part 3 Core metal 4 Heat insulation layer 5 Release layer 6, 6a

Claims (6)

A self-heating type fixing roller having a cylindrical resistor layer that generates heat when energized,
A plurality of energization portions that contact the resistor layer and extend in the circumferential direction;
A self-heating type fixing roller in which the energization portion has an electrical resistivity smaller than that of the resistor layer.   The self-heating type fixing roller according to claim 1, wherein the conducting portion is annular.   The self-heating type fixing roller according to claim 1, wherein the plurality of conductive portions are arranged at equal intervals in the axial direction.   The self-heating type fixing roller according to claim 1, wherein an axial width of the conducting portion is constant.   The self-heating type fixing roller according to any one of claims 1 to 4, wherein an average width of the plurality of conductive portions is 0.3 mm or more and 5 mm or less.   The self-heating type fixing roller according to any one of claims 1 to 5, wherein an average interval between the plurality of conductive portions is 0.5 mm or more and 10 mm or less.

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