JP2006194988A - Fixing belt and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing belt which has improved wear resistance, heat conductivity, thickness reduction, heat resistance and flexibility. <P>SOLUTION: The fixing belt has at least a metallic layer and a mold releasing layer provided on the metallic layer. The metallic layer consists of a nickel-iron-cobalt alloy manufactured by an electroforming method. The nickel-iron-cobalt alloy satisfies a relation expressed by following formulas: 20≤N≤80 (1), 10≤F≤50 (2) and 10≤C≤70 (3), wherein nickel content in the nickel-iron-cobalt alloy is N(mass%), iron content therein is F(mass%) and cobalt content therein is C(mass%). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing belt used in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus, and an image forming apparatus including the fixing belt.

In an image forming apparatus, a recording material (transfer material sheet, electrofax sheet, electrostatic recording paper, OHP sheet, printing paper, and formatting paper is used in image forming process means such as an electrophotographic process, an electrostatic recording process, and a magnetic recording process. As a fixing device that heats and fixes a non-fixed image (toner image) of target image information formed and supported by a transfer method or a direct method on a recording material surface as a permanently fixed image, a thermal roller type device is widely used. It was used. In a heat roller type apparatus, a heat source such as a halogen heater is generally used in the roller.

  On the other hand, apparatuses of a system that heats a resin belt or a metal belt having a small heat capacity using a ceramic heater as a heat source have been widely proposed and implemented. That is, in this heating method apparatus, generally, a nip portion is formed by sandwiching a heat-resistant belt (fixing belt) between a ceramic heater as a heating body and a pressure roller as a pressure member. A recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced between the fixing belt and the pressure roller, and is nipped and conveyed together with the belt. The unfixed toner image is fixed on the surface of the recording material by heat and pressure applied to the recording material.

  This belt heating type heat fixing apparatus can be configured as an on-demand type apparatus using a low heat capacity member as a belt. That is, it is only necessary to energize a ceramic heater as a heat source to generate heat at a predetermined fixing temperature only when image formation is performed by the image forming apparatus. In this type of fixing apparatus, image formation is performed after the image forming apparatus is turned on. There are advantages such as a short waiting time until execution is possible (quick start performance) and significantly low power consumption during standby (power saving).

  FIG. 3 shows a configuration example of this type of heat fixing apparatus. In this heating-type heat fixing apparatus, a nip portion N is formed by sandwiching a heat-resistant belt (fixing belt 310) between a ceramic heater 312 as a heating body and a pressure roller 330 as a pressure member, and the nip. The recording material P on which an unfixed toner image t to be image-fixed is formed and supported is introduced between the fixing belt 310 and the pressure roller 330, and is conveyed together with the belt. The heat of the heater 312 is applied to the recording material P through the fixing belt 310, and the unfixed toner image t is fixed to the surface of the recording material P by heat and pressure with this heat and the applied pressure of the nip portion.

  A heat-resistant resin or the like is used as a belt in such a belt heating method, and a polyimide resin excellent in heat resistance and strength is used. However, when the machine is further increased in speed and durability, the resin film has insufficient strength. For this reason, it has been proposed to use a belt having a base layer made of a metal having excellent strength, such as SUS, nickel, copper, or aluminum.

In addition, an induction heating method is also disclosed in which a metal belt is used and self-heats by an eddy current due to electromagnetic induction (see, for example, Patent Documents 1 and 4). FIG. 4 shows an example of the configuration of this heating type heat fixing apparatus. FIG. 5 shows a model diagram of the magnetic field generating means of the heat fixing apparatus of FIG. The magnetic cores 417a, 417b and 417c are high permeability members, and the exciting coil 418 generates an alternating magnetic flux by an alternating current (high frequency current) supplied from an exciting circuit (not shown). When this alternating magnetic flux acts on the metal layer of the fixing film, an eddy current is generated and the metal layer generates heat. The heat heats the fixing film through the elastic layer and the release layer of the fixing film, heats the recording material P that is passed through the nip portion N, and heat-fixes the toner image. That is, a heating and fixing device has been proposed in which eddy current is generated in the belt itself or a conductive member close to the belt by magnetic flux and heat is generated by Joule heat. In this electromagnetic induction heating type heating and fixing apparatus, the heat generation area can be made closer to the object to be heated, so that the efficiency of energy consumption can be increased.
As a fixing belt driving method of a belt heating type heat fixing apparatus, a belt press-contacted by a film guide for guiding the inner surface of the belt and a pressure roller as shown in FIG. 3 is driven to rotate by the rotation driving of the pressure roller. There are a method (pressure roller driving method) and a method of rotating the pressure roller in a driven manner by driving an endless belt stretched between a driving roller and a tension roller as shown in FIG.

  As a fixing belt using a metal belt, a belt using a nickel fixing belt having a surface roughness of a heater surface contact portion of less than 0.5 μm and a thickness of about 40 μm is disclosed (for example, see Patent Document 2). .) Also disclosed is a nickel fixing belt having a thickness of 10 to 35 μm having a coating layer having releasability on the outer peripheral surface and a resin layer on the inner peripheral surface (see, for example, Patent Document 3).

 As described above, a seamless belt base material is generally used for a fixing belt used in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus. For example, a seamless belt base material made of a nickel material is generally manufactured by an electroplating method (sometimes referred to as an electroforming method) using a nickel sulfate bath, a nickel sulfamate bath, or the like.

In Patent Document 2 or 3,
In this electroplating method, a mother die having a required shape is used, electroforming film formation is performed on the outer periphery of the mother die, and the seamless belt base material is manufactured by drawing from the mother die. However, when the conventional nickel seamless belt is heated to 180 ° C. or higher during fixing, the surface is oxidized. For example, in the heating fixing device of the belt heating type shown in FIG. 3, the ceramic heater 312 and the belt guide 316 In this contact, scraping occurs gradually and the frictional resistance increases. For this reason, the torque driven by the pressure roller (pressure member) 330 increases, and the designed rotation cannot be obtained.

Therefore, conventionally, a sliding layer has been provided on the belt guide side (inner peripheral surface) of the seamless belt base material. This is to reduce resistance due to contact between the belt guides 316 and 416 and the sliding plates 340 and 440 in FIG. 3 and FIG. 4 and the fixing belt. It has been proposed that the sliding layer is formed using a polyimide resin. However, the thermal conductivity of so-called resin materials including polyimide resin is about 1/300 times that of nickel as a base material (nickel; 0.92 W / cm · ° C., polyimide resin; 2.9 × 10 ^-3 W / cm · ° C), the start-up time becomes longer, and the merit of nickel material with good thermal conductivity is hidden. Polyimide resin has a high material cost, and the process cost also increases because it is formed on the inner peripheral surface of the belt. In many cases, moisture is absorbed by the polyimide film during the process of forming the polyimide resin, and the excellent characteristics of the polyimide are lost.
On the other hand, a lubricating metal layer in which ceramic particles or synthetic resin particles are dispersed in a metal matrix has been proposed on the surface of the heating member that slides with the support member (see, for example, Patent Document 4). By providing a metal layer in which ceramic particles or synthetic resin particles are dispersed in a metal matrix, the sliding resistance of the sliding surface of the heating member with the support member is reduced, and further, the sliding resistance is improved by improving the paper passing durability. Can be suppressed. However, since the thermal conductivity is still smaller than that of nickel as a base material, there remains a problem in increasing the printing speed of the heat fixing device.

On the other hand, a metal tube by a plastic working method has also been proposed (for example, see Patent Document 5).
Plastic processing methods include drawing, drawing, and processing methods that handle the substrate during drawing. However, if the tube thickness is reduced, for example, in the case of drawing, the die wears frequently. In addition, it is disadvantageous that it is mechanically difficult to reduce the thickness to 30 μm or less.

In the future, demands for further energy saving and space saving will become strict, and downsizing of the heat fixing device used in the image forming apparatus and reduction in the inner diameter of the fixing belt are being promoted. Therefore, a fixing belt having a metal layer is required to have oxidation resistance at high temperatures, lubricity, thermal conductivity, thinning, heat resistance, flexibility, and the like.
JP-A-7-114276 Japanese Patent Laid-Open No. 7-13448 JP-A-6-222695 Japanese Patent Laid-Open No. 2001-6868 JP 2001-225134 A

  The present invention has been made to solve the above-mentioned problems of the prior art, and in a heat fixing apparatus that enables low energy heating, wear resistance, thermal conductivity, thinning, heat resistance, and flexibility are improved. An object of the present invention is to provide a fixed fixing belt.

The above object is achieved by the present invention described below.

(1) A fixing belt having at least a metal layer and a release layer provided on the metal layer, wherein the metal layer is made of a nickel-iron-cobalt alloy manufactured by an electroforming method, When the nickel content in the iron-cobalt alloy is N (mass%), the iron content is F (mass%), and the cobalt content is C (mass%), the nickel-iron-cobalt alloy Satisfies the relationship represented by the following formula.
20 ≦ N ≦ 80 (1)
10 ≦ F ≦ 50 (2)
10 ≦ C ≦ 70 (3)
(2) The fixing belt according to (1), wherein an elastic layer is provided between the release layer and the metal layer.

  (3) The fixing belt according to (2), wherein the elastic layer is formed from silicone rubber, fluorine rubber, and fluorosilicone rubber.

  (4) An image forming apparatus comprising the fixing belt according to any one of (1) to (3).

  In a fixing belt having at least a release layer and a metal layer, the metal layer is made of a nickel-iron-cobalt alloy manufactured by an electroforming method, and the nickel, iron, and cobalt contents are controlled within a predetermined range. As a result, it is possible to provide a thinned fixing belt excellent in wear resistance, particularly heat resistance, thermal conductivity, flexibility, and flexibility that can be applied to high-speed printing.

The fixing belt of the present invention is a fixing belt having at least a release layer and a metal layer, and the metal layer is made of a nickel-iron-cobalt alloy manufactured by an electroforming method. When the nickel content is N (mass%), the iron content is F (mass%), and the cobalt content is C (mass%), this nickel-iron-cobalt alloy is expressed by the following formula. It is characterized by satisfying the relationship.
20 ≦ N ≦ 80 (1), 10 ≦ F ≦ 50 (2), 10 ≦ C ≦ 70 (3)
Thereby, it can be set as the metal layer which has high heat resistance and high flexibility which does not generate | occur | produce the hardness of a metal layer, a crack, a fracture | rupture, etc.

In addition, the metal layer of the present invention may be exposed to a high temperature for a certain period of time when the elastic layer or release layer formed on the outer peripheral surface is cured, and is also intermittently subjected to high temperature heating during fixing. There is a case. In order to have further heat resistance to cope with these, it is more preferable that the contents of nickel, iron and cobalt in the nickel-iron-cobalt alloy satisfy the relationship represented by the following formula.
20 ≦ N ≦ 40 (4), 20 ≦ F ≦ 50 (5), 10 ≦ C ≦ 60 (6)
On the other hand, in the case of conventional electroformed nickel, as described above, the surface is oxidized by heating (180 ° C. or higher) during fixing, and contact with the ceramic heater 312 or the belt guide 316 as shown in FIG. It has the disadvantage of scraping. However, the metal layer produced by the electroforming method in the present invention is a nickel-iron-cobalt ternary alloy containing iron and cobalt in addition to nickel, and even when exposed to high temperatures, the metal layer 1 has heat resistance that does not cause sulfur embrittlement due to the sulfur component in the brightener used when the electroforming method is produced, and has flexibility even when the hardness is increased. That is, the fixing belt of the present invention does not scrape even when it comes into contact with the opposing structure, and can have wear resistance, good slipperiness, sufficient heat resistance, and flexibility.

(1) Fixing Belt The fixing belt of the present invention will be described.

  FIG. 1 is a model diagram showing a layer structure of a fixing belt 10 according to an embodiment of the present invention. The fixing belt 10 of the present invention shown in FIG. 1 includes a metal layer 1 of an endless metal belt made of a nickel-iron-cobalt alloy manufactured by an electroforming method, an elastic layer 2 laminated on an outer peripheral surface thereof, and further It has the release layer 3 laminated | stacked on the outer peripheral surface. In the fixing belt 10, the metal layer 1 side is the inner peripheral surface side (belt guide surface side), and the release layer 3 side is the outer peripheral surface side (pressure roller surface side). A primer layer (not shown) may be provided for adhesion between the metal layer 1 and the elastic layer 2 or between the elastic layer 2 and the release layer 3. A known primer such as a silicone, fluorine, epoxy, or polyamideimide may be used as the primer, and the layer thickness is usually about 1 to 10 μm.

  FIG. 2 is a model diagram showing a layer structure of the fixing belt 20 according to another embodiment of the present invention. The release layer 3 may be formed directly on the metal layer 1 without forming the elastic layer 2 on the surface of the metal layer 1. In particular, when the amount of toner on the recording material is small and the unevenness of the toner layer is relatively small, in the case of heat fixing or in the structure for improving heat conduction, such an elastic layer is omitted. It can be.

  On the other hand, even in the case of the fixing belt shown in FIGS. 1 and 2, if the heat fixing device mechanism requires insulation from the belt guide or the like, a highly heat-resistant resin layer such as polyimide or polyimide amide is used as the metal layer. There is no problem in laminating on one belt guide side. Further, since this resin layer slides with the belt guide, a solid lubricant or an oxide filler for improving the thermal conductivity may be added. The thickness of this resin layer is preferably 50 μm or less, particularly about 3 to 20 μm.

The fixing belt 10 or 20 of the present invention can be used in a belt heating system using a ceramic heater or an electromagnetic induction heating system heat fixing apparatus.
<Metal layer>
The metal layer 1 is made of an endless metal belt manufactured by an electroforming method, and the endless metal belt is made of a nickel-iron-cobalt alloy. In the fixing belt of the present invention, when the elastic layer 2 and the release layer 3 are formed on the outer peripheral surface of the metal layer 1, the fixing belt is usually heated at 200 to 300 ° C. for a predetermined time to be cured, and also heated at 180 ° C. or more during fixing. Receive. In addition, when the metal layer 1 is manufactured by an electroforming method, the sulfur component in the brightener is an essential component in order to improve molding accuracy and reduce electrodeposition stress to facilitate demolding. In the film formed at this time, iron ions in the plating bath and sulfur components in the brightener co-deposit. The metal layer shows a tendency to gradually increase in hardness when exposed to the above-mentioned high-temperature heating. Eventually, the reaction of iron (Fe) and sulfur (S) in the coating into a compound called FeS causes sulfur embrittlement. Occurs, hardness deteriorates, and cracks and breaks occur during fixing. That is, the flexibility is deteriorated.

  However, the metal layer 1 made of the nickel-iron-cobalt alloy is superior in wear resistance and heat resistance as compared with the metal layer made of nickel or the like in the prior art, and this wear resistance is affected by the iron compound. Cobalt was found to be effective in heat resistance.

In order to obtain the above effect, the metal layer made of a nickel-iron-cobalt alloy manufactured by an electroforming method has a nickel content of N (mass%) and an iron content of the nickel-iron-cobalt alloy. When the content rate of F (mass%) and cobalt is C (mass%), this nickel-iron-cobalt alloy needs to satisfy the relationship represented by the following formula.
20 ≦ N ≦ 80 (1), 10 ≦ F ≦ 50 (2), 10 ≦ C ≦ 70 (3)
When the nickel content is 80% by mass or more, the effect of adding iron or cobalt becomes small, and sufficient wear resistance and heat resistance cannot be obtained. On the other hand, when the content is 20% by mass or less, the content of iron and cobalt is high, the tensile stress of the coating is remarkably increased, and electroforming film formation is difficult, which is unsuitable for manufacturing an electroforming belt.

  As the iron content increases, the hardness tends to increase as described above, and the wear resistance also improves due to the influence of the iron compound, but the FeS reaction peak temperature also shifts to the high temperature side and the heat resistance is slightly Get better. However, the heat resistance tends to decrease when the iron content reaches a peak around 35% by mass, and when it exceeds 50% by mass, a very brittle film tends to be formed under high temperature heating. Therefore, the range of the iron content that can obtain good characteristics needs to be 10 mass% or more and 50 mass% or less.

  On the other hand, with respect to cobalt, effects such as suppression of sulfur embrittlement and high hardness were confirmed as described above, but the effect is not so changed when the cobalt content is 20% by mass or more. However, even if it is contained in a large amount, no harmful effect is recognized. Accordingly, the range of the cobalt content is limited to 70% by mass or less, limited by the content of other nickel and iron. On the other hand, even nickel-iron alloys that do not contain cobalt sufficiently satisfied the durability depending on the composition, but for heat resistance, if even a small amount of cobalt is contained, the heat resistance is drastically improved, so that it is 10% by mass or more. did. In addition, since cobalt has a particularly high chemical cost, it is better to reduce the amount used as much as possible.

Note that the nickel-iron-cobalt alloy is particularly useful when wear resistance and heat resistance are required particularly when there is a possibility of exposure to high temperature heating or when intermittent high temperature heating is required during fixing. More preferably, the contents of nickel, iron and cobalt in the inside satisfy the relationship represented by the following formula.
20 ≦ N ≦ 40 (4), 20 ≦ F ≦ 50 (5), 10 ≦ C ≦ 60 (6)
The endless nickel-iron-cobalt alloy belt having the above-mentioned predetermined nickel, iron and cobalt content used in the present invention is preferably formed by an electroforming process, preferably using a straight cylindrical matrix such as stainless steel as a cathode. Manufactured. Here, the right cylindrical shape means a cylindrical shape whose cross sections perpendicular to the longitudinal direction are all the same circle.

  As the plating bath in this case, a general electroforming bath such as a sulfate bath, a sulfamate bath, a chloride bath, etc. can be used, and a pit inhibitor, a brightener, a pH adjuster, etc. can be added as appropriate. Good.

  As an example, a nickel-iron-cobalt plating bath and plating conditions are shown below. Moreover, by controlling the addition amount of each chemical, the plating bath temperature, and the current density within the ranges shown below, the conditions of the expressions (1) to (3), and further the expressions (4) to (6) are satisfied. Nickel-iron-cobalt alloy belts can be manufactured.

(Plating bath composition) Nickel sulfate hexahydrate; 120-300 g / l
Ferrous sulfate heptahydrate; 2-30 g / l
Cobalt sulfate heptahydrate; 10-80 g / l
Pit inhibitor (sodium lauryl sulfate);
0.002 g / l
Brightener (saccharin sodium); 0.01-5 g / l
pH adjuster
pH adjuster (1N sulfuric acid); appropriate amount (plating conditions) electroforming bath temperature; 50 ± 10 ° C
pH: 2.7 ± 0.3
Cathode current density: 1 to 20 A / dm ²
Examples of the brightener include stress reducing agents and primary brighteners such as saccharin, sodium saccharin, sodium benzenesulfonate, and sodium naphthalenesulfonate. Among them, saccharin sodium is selected in the present invention. However, since sulfur embrittlement tends to occur when the content of sulfur incorporated in the coating increases, it is preferably controlled at 5 g / l or less in a plating bath. Further, it has been found that it is preferably 0.01 g / l or more in order to obtain the strength and flexibility required for the fixing belt or to adjust the stress suitable for demolding.

  The thickness of the metal layer 1 is 100 μm or less, particularly 50 μm or less in order to reduce the heat capacity and improve the quick start property when used in a belt heating type heat fixing device using a ceramic heater shown in FIG. It is preferable that it is 10 micrometers or more. Since the electroformed nickel-iron-cobalt alloy in the present invention has higher spring properties than electroformed nickel, it is difficult to be plastically deformed even if it is thinner than electroformed nickel. In order to increase the nip portion with the pressure roller, it is better to reduce the thickness of the metal layer 1, and there are many future needs. In that respect, the electroformed nickel-iron-cobalt alloy in the present invention is more advantageous than the SUS tube produced by the plastic working method described above.

  In the case of the electromagnetic induction heating type heat fixing apparatus shown in FIG. 4, the thickness of the metal layer 1 is thicker than the skin depth represented by the following formula, usually 1 μm or more, preferably 10 μm or more, and usually 200 μm or less. , Preferably 100 μm or less, more preferably 70 μm or less.

The skin depth σ [m] is determined by the frequency f [Hz] of the excitation circuit, the magnetic permeability μ [−], and the specific resistance ρ [Ωm] σ = 503 × (ρ / fμ) ^1/2
It is expressed. This indicates the depth of absorption of electromagnetic waves used in electromagnetic induction, and the intensity of electromagnetic waves deeper than this is 1 / e (e represents the base of natural logarithm) or less. Most of the energy is absorbed up to this depth.

  The electrocast nickel-iron-cobalt alloy in the present invention has a higher magnetic flux density as the amount of iron is larger than that of electroformed nickel, but the specific resistance is 2 to 5 times greater than that of nickel. For this reason, if it is too thin, most of the electromagnetic energy cannot be absorbed and the efficiency may deteriorate. On the other hand, if the metal layer 1 is too thick, the rigidity becomes high, and the flexibility becomes poor, which may make it difficult to use as a rotating body.

<Elastic layer>
The elastic layer 2 may or may not be provided. By providing the elastic layer 2, heat transfer can be ensured by covering the heated image at the nip portion, and the restoring force of the metal layer 1 can be supplemented to reduce fatigue due to rotation and bending. Further, by providing the elastic layer 2, the followability of the surface of the release layer of the fixing belt to the surface of the unfixed toner image can be increased, and heat can be efficiently transmitted. The fixing belt provided with the elastic layer 2 is particularly suitable for heat fixing of a color image having a large amount of unfixed toner.

  The material of the elastic layer 2 is not particularly limited, and a material having good heat resistance and good thermal conductivity may be selected. As the material for the elastic layer 2, silicone rubber, fluororubber, fluorosilicone rubber and the like are preferable, and silicone rubber is particularly preferable.

  Examples of the silicone rubber raw material used to form the elastic layer 2 include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polytrifluoropropylvinylsiloxane, polymethylphenylsiloxane, polyphenylvinylsiloxane, Examples thereof include a copolymer composed of monomer units constituting the polysiloxane.

  If necessary, the elastic layer 2 may be provided with a reinforcing filler such as dry silica or wet silica, calcium carbonate, quartz powder, zirconium silicate, clay (aluminum silicate), talc (hydrous magnesium silicate), alumina (aluminum oxide). Further, a filler such as Bengala (iron oxide) may be included in the elastic layer.

  In order to obtain a good fixed image quality, the thickness of the elastic layer 2 is preferably 10 μm or more, particularly preferably 50 μm or more, and is preferably 1000 μm or less, particularly 500 μm or less. When a color image is printed, a solid image is formed over a large area on the recording material P, particularly in a photographic image. In this case, if the heating surface (release layer 3) cannot follow the unevenness of the recording material or the unevenness of the toner layer, uneven heating occurs, and uneven glossiness occurs in the image where the heat transfer amount is large and small. That is, the glossiness is high at the portion where the heat transfer amount is large, and the glossiness is low at the portion where the heat transfer amount is small. If the elastic layer 2 is too thin, the unevenness of the image gloss may be generated because it cannot follow the unevenness of the recording material or the toner layer. On the other hand, if the elastic layer 2 is too thick, the thermal resistance of the elastic layer may increase and it may be difficult to realize a quick start.

  The hardness (JIS-K-6253) of the elastic layer 2 is preferably 60 ° or less, more preferably 45 ° or less, because the occurrence of uneven image gloss is sufficiently suppressed and good fixed image quality is obtained.

The thermal conductivity λ of the elastic layer 2 is preferably 2.5 × 10 ⁻³ [W / cm · ° C.] or more, and more preferably 3.3 × 10 ⁻³ [W / cm · ° C.] or more. Further, it is preferably 8.4 × 10 ⁻³ [W / cm · ° C.] or less, and more preferably 6.3 × 10 ⁻³ [W / cm · ° C.] or less. When the thermal conductivity λ is too small, the thermal resistance increases, and the temperature rise in the surface layer (release layer 3) of the fixing belt may be delayed. When the thermal conductivity λ is too large, the hardness of the elastic layer 2 may increase or the compression set may increase.

  The elastic layer 2 is a known method, for example, a method of coating a material such as liquid silicone rubber on the metal layer with a uniform thickness by means such as a blade coating method, and heat curing, molding a material such as liquid silicone rubber. It may be formed by a method of injecting into a mold and vulcanizing and curing, a method of vulcanizing and curing after extrusion molding, a method of vulcanizing and curing after injection molding, or the like.

<Release layer>
The material of the release layer 3 is not particularly limited, and a material having good release properties and heat resistance may be selected. The release layer 3 includes fluororesins such as PFA (tetrafluoroethylene / perfluoroalkyl ether copolymer), PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), and silicone resins. Fluorosilicone rubber, fluororubber, silicone rubber and the like are preferable, and PFA is more preferable. If necessary, the release layer can contain a conductive agent such as carbon and tin oxide. Although content of a electrically conductive agent is not specifically limited, Generally, it is preferable to make it contain in 10 mass% or less with respect to the total mass of the material which forms a mold release layer.

  The thickness of the release layer 3 is preferably 1 μm or more, and preferably 100 μm or less. When the release layer 3 is too thin, a portion having poor release properties may be formed due to uneven thickness of the release layer 3, or durability may be insufficient. If the release layer 3 is too thick, the thermal conductivity may be deteriorated. In particular, in the case of a resin release layer, the hardness becomes high and the effect of the elastic layer 2 may be attenuated.

  The release layer 3 is formed by a known method, for example, in the case of forming a fluororesin-based release layer, by coating with a dispersion and coating of fluororesin powder, drying and firing, or by previously forming a tube. What is necessary is just to form by the method of coat | covering and adhere | attaching things. Also, when forming a rubber release layer, it may be formed by a method of injecting a liquid material into a mold and vulcanizing and curing, a method of vulcanizing and curing after extrusion molding, a method of vulcanizing and curing after injection molding, etc. Good.

  Also, liquid silicone rubber is injected into the gap between the tube that has been primed on the inner surface in advance and the endless electroformed nickel-iron-cobalt alloy belt that has been primed on the outer circumferential surface, and heated to cure and bond the silicone rubber. Thus, the elastic layer and the release layer can be formed simultaneously.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example, measurement of nickel, iron and cobalt content of nickel-iron-cobalt alloy of endless metal belt in comparative example, measurement of reaction peak temperature of iron and sulfur, measurement of hardness by heat treatment, and fixing of examples and comparative examples The belt idling durability test and the actual machine durability paper passing test were performed as follows.

<Measurement of nickel, iron and cobalt content of nickel-iron-cobalt alloy>
Measurement was performed using an energy dispersive X-ray analyzer EDAX Phoenix (trade name) manufactured by Philips Electron Optics.

<Measurement of reaction peak temperature of iron and sulfur in nickel-iron-cobalt alloy>
The reaction between iron and sulfur by heating usually occurred at around 400 ° C., and was measured with a differential scanning calorimeter DSC8230 manufactured by Rigaku Corporation. The peak temperature of this reaction (hereinafter referred to as Tp) was recorded.

<Measurement of hardness by heat treatment of nickel-iron-cobalt alloy>
In order to evaluate heat resistance, the hardness difference before and after heat treatment was compared. As the heat treatment conditions, the heat treatment temperature was set in increments of 50 ° C. between 250 to 500 ° C., held for 30 minutes at each temperature condition, and then gradually cooled to measure the hardness. The hardness was measured using a hardness measuring device MVK-E (trade name) manufactured by Akashi Co., Ltd., and the Vickers hardness was measured based on JIS-Z-2244 with a load of 50 g.

<Ideal rotation durability test>
[Idle rotation durability test using a heater heating type belt heating type heat fixing device]
The fixing belt of the example or the comparative example was mounted on a full color LBP LASER SHOT “LBP-2040” manufactured by Canon Inc., which is a belt heating type heat fixing device of a heater heating method, to obtain a heat fixing device. Using this heat fixing apparatus, an idling durability test was conducted as follows.

  While adjusting the heater temperature of the heat fixing device to 210 ° C., the pressure roller was pressed against the fixing belt with a predetermined pressure, and the fixing belt was driven to rotate by the pressure roller. As the pressure roller, a φ16 mm pressure roller in which an elastic layer made of silicone rubber having a thickness of 3 mm was coated with a 30 μm PFA tube was used. In this idling durability test, the pressure was 200 N, the nip portion was 6 mm × 230 mm, and the surface speed of the fixing belt was 87 mm / s. Further, 0.5 g of HP3000 manufactured by Dow Corning Co., Ltd. was applied to the belt guide sliding plate (340 in FIG. 3) to test the sliding.

  Under this idling test, the time until cracks and breaks were confirmed while visually and microscopically observing the fixing belt to determine the durability time.

  The minimum endurance time of the fixing belt calculated from the process speed of the heat fixing device and the safety factor is 500 hours, but the endurance life (endurance time) of the fixing belt of the present invention is set to 700 hours or more, and the endurance time is 700 hours. The test was terminated when 700 hours were exceeded.

[Improvement of idling with an electromagnetic induction heating belt heating type fixing device]
A full-color LBP LASER SHOT “LBP-2710” manufactured by Canon Inc., which is an electromagnetic induction type belt heating type heat fixing device, is mounted with the fixing belt of the example or the comparative example to obtain a heat fixing device. While adjusting the heater temperature of the heat fixing device to 220 ° C., the pressure roller was pressed against the fixing belt with a predetermined pressure, and the fixing belt was driven to rotate by the pressure roller. As the pressure roller, a Φ30 mm rubber roller in which a 3 mm thick silicone layer was covered with a 30 μm PFA tube was used. In this experiment, the pressure was 200 N, the fixing nip was 7 mm wide × 230 mm long, and the surface speed of the fixing belt was tested under the conditions of 120 mm / sec, which is a high-speed printing speed. Further, 0.5 g of HP3000 manufactured by Dow Corning Co., Ltd. was applied to the belt guide sliding plate (440 in FIG. 4) to test the sliding.

<Actual machine durability test>
By using the image forming apparatus equipped with the full-color LBP LASER SHOT "LBP-2040" manufactured by Canon Inc., the heat fixing device used in the above-mentioned idling endurance test, 100,000 images were drawn and the actual machine endurance paper passing test Went.

In the actual endurance paper passing test, the pressure applied by the pressure roller was 200 N, the nip portion was 6 mm × 230 mm, the fixing temperature was 210 ° C., and the process speed was 87 mm / s.
[Examples 1-14, Comparative Examples 1-11]

<Production and evaluation of endless metal belts>
An endless fixing belt made of a nickel-iron-cobalt alloy produced by electroforming was produced by the following means. The plating conditions are shown below.

Nickel sulfate hexahydrate; 20-140 g / l
Ferrous sulfate heptahydrate; 5-60g / l
Cobalt sulfate heptahydrate; 0-50 g / l
Boric acid; 25 g / l
Sodium chloride; 25 g / l
Sodium lauryl sulfate; 0.02 g / l
Saccharin sodium; 1 g / l
pH adjustment (1N sulfuric acid); appropriate amount electroforming bath temperature; 50 ° C
pH: 2.7 ± 0.3
Cathode current density: 2-12 A / dm ²
A stainless steel straight cylindrical matrix is dipped in the nickel-iron-cobalt plating bath to form a cathode, and a nickel-iron-cobalt alloy is electrodeposited on the outer peripheral surface of the matrix for 30 minutes. It was removed from the mold, and an endless metal belt having an inner diameter of Φ24 mm, a thickness of 30 μm, and both ends were temporarily cut to a length of about 300 mm was produced.

  Then, a 300 μm silicone rubber layer (DY35-4039A / B: manufactured by Toray Dow Corning Co., Ltd.) is used as the elastic layer 2 on the outer peripheral surface of the endless metal belt, and a 30 μm PFA tube (SME manufactured by Gunze Co., Ltd.) is used as the release layer 3. Heat shrinkable type) were sequentially laminated via primer application, and both ends were cut to finally produce a fixing belt having a length of 250 mm.

  Moreover, using the temporary cut piece of the metal layer 1, the nickel, iron, and cobalt content of the nickel-iron-cobalt alloy belt and the peak temperature of the FeS reaction were measured. Furthermore, the hardness change by the said heat processing was confirmed about some conditions in it. On the other hand, with respect to the prepared fixing belt, the actual machine was tested using the idling durability test using the ceramic heater heating method and the electromagnetic induction heating method fixing device shown in FIG. 3 and an image forming apparatus equipped with these heating fixing devices. A durability paper passing test was conducted.

  Table 1 shows the production conditions of the endless metal belts used in the examples and comparative examples, and the measurement results.

  FIG. 7 shows the results of plotting the nickel, iron, and cobalt contents of the nickel-iron-cobalt alloy in Table 1 and the peak temperature Tp of the FeS reaction based on the measurement results.

  According to Table 1 and FIG. 7, in the fixing belts of Examples 1 to 14, the nickel content in the nickel-iron-cobalt alloy is N (mass%), the iron content is F (mass%), and cobalt. When the content of C is C (mass%), it is in the range of 20 ≦ N ≦ 80, 10 ≦ F ≦ 50, 10 ≦ C ≦ 70 of claim 1, the FeS reaction peak temperature is high, and the durability time is all Over 500 hours.

  In addition, among the above ranges, those in which the nickel, iron, and cobalt contents are in the range of 20 ≦ N ≦ 40, 20 ≦ F ≦ 50, and 10 ≦ C ≦ 60 are further excellent in heat resistance and durability. Since 700 hours were reached, the experiment was stopped halfway.

  On the other hand, the fixing belts of Comparative Examples 1 to 11 are made of a nickel-iron-cobalt alloy that does not meet at least one condition within the range of the nickel, iron, and cobalt contents shown in Examples 1 to 14. A fixing belt using a layer.

  First, the metal belt having a nickel content of 20% by mass or less shown in Comparative Example 1 and Comparative Example 2 has a very high tensile stress, and peels off during plating, and even if it can be electroformed, it is removed from the mother die. The metal belt shape could not be obtained.

  The fixing belt using a metal belt having a nickel content of 80% by mass or more shown in Comparative Example 8 does not have a sufficient wear resistance effect due to the iron content, and the inner peripheral surface is subjected to sliding wear during the idling durability test. However, since the rotational torque of the pressure roller increased due to the metal powder, the operation was stopped in 430 hours.

  Among other comparative examples, the metal belt in which the iron content of the nickel-iron alloy shown in comparative example 4 is about 20% by mass cleared the durability time of 700 hours. There were many conditions for cracks. The surface of the metal belt having an iron content of 55% by mass or more is liable to generate a mat shape or protruding foreign matter, which causes cracks.

  Further, among the examples in Table 1, the FeS reaction peak temperature was as high as 460 ° C. or higher and the durability test was continued for 700 hours or more. Four conditions were selected in total for Example 4 and Comparative Example 9, and the change in hardness before and after heat treatment was confirmed using cut pieces of each metal layer. The results are shown in FIG.

  In Example 4 and Example 5, as an effect of cobalt, the hardness tends to increase up to about 400 ° C., and thermal deterioration does not occur. The hardness also increased from 450 to 900 in terms of Vickers hardness. On the other hand, in Comparative Example 4 and Comparative Example 9, the heat resistance was maintained only up to about 300 ° C., and the Vickers hardness at that time was less than 600.

  In Comparative Example 4, the durability test result was as good as in the example, but the heat resistance did not reach the metal belt containing cobalt.

  From the above results, it was found that the gray area shown in FIG. 7 is an area having high heat resistance and high durability in the electroformed nickel-iron-cobalt alloy.

Experimental example 2
Further, in the actual machine endurance paper passing test, the image forming endurance test for 100,000 sheets was completed without any trouble for those equipped with the fixing belts of Examples 1 to 14. On the other hand, with the fixing belts of Comparative Examples 3 to 11 except Comparative Examples 1 and 2 that could not be molded, the image was distorted at 10,000 sheets or less, making it impossible to pass the paper. There was a problem with not having the mechanical strength to do.

Experimental example 3
Further, in the idling durability test using the electromagnetic induction heating type belt heating type heat fixing device, all of the devices equipped with the fixing belts of Examples 1 to 14 cleared the durability time of 500 hours. Further, it was confirmed that all of the devices equipped with the fixing belts of Examples 1 to 11 cleared 700 hours and had sufficient heat resistance and durability. On the other hand, the fixing belts of Comparative Examples 3 to 11 had cracks with a durability time of 500 hours or less, and the durability was poor.

  Those equipped with the fixing belts of Examples 1 to 14 completed the endurance test for 100,000 sheets without trouble. On the other hand, in the cases where the fixing belts of Comparative Examples 3 to 11 were mounted, the image was distorted at 10,000 sheets or less, and the paper could not be passed.

  According to the present invention, it is possible to provide a fixing belt having improved wear resistance, thermal conductivity, thinning, heat resistance and flexibility.

FIG. 3 is a schematic diagram illustrating an example of a layer configuration of a fixing belt of the present invention. FIG. 3 is a schematic diagram illustrating an example of a layer configuration of a fixing belt of the present invention. It is a schematic block diagram of the image heating apparatus used for the first embodiment. It is a schematic block diagram of the image heating apparatus used for the 2nd embodiment. It is a magnetic field generation | occurrence | production means model figure of the image heating apparatus used for the example of 1st Embodiment. It is a schematic block diagram of the image heating apparatus used for the other example embodiments. 6 is a map showing the reaction peak temperature of FeS with respect to the composition ratio of nickel-iron-cobalt alloy. It shows the change in hardness due to the heat treatment temperature with respect to the composition ratio of the nickel-iron-cobalt alloy. (Retention time: 30 minutes)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal layer 2 Elastic layer 3 Release layer 10, 20 Fixing belt 300, 400, 600 Heat fixing device 310, 410, 610 Fixing belt 312 Ceramic heater 312b Heat generation layer 312c Protective layer 316, 416, 616 Belt guide 322, 422, 622 Rigid stay for pressure 330, 430, 630 Pressure member (pressure roller)
330a, 430a Core metal 330b, 430b Elastic layer 340, 440, 640 Sliding plate 416a, 416b Belt guide 417a, 417b, 417c Magnetic core 418, 618 Excitation coil 418a, 418b Power supply part 419, 619 Insulating member 426 Temperature sensor 427 Excitation Circuits 617a, 617b, 617c Magnetic core 631 Driving roller 632 Tension roller M Driving means N Nip portion t Fixed toner image P Recording material

Claims (4)

A fixing belt having at least a metal layer and a release layer provided on the metal layer, wherein the metal layer is made of a nickel-iron-cobalt alloy manufactured by an electroforming method, and the nickel-iron-cobalt When the nickel content in the alloy is N (mass%), the iron content is F (mass%), and the cobalt content is C (mass%), the nickel-iron-cobalt alloy is: A fixing belt satisfying the relationship represented by the formula:
20 ≦ N ≦ 80 (1)
10 ≦ F ≦ 50 (2)
10 ≦ C ≦ 70 (3)   The fixing belt according to claim 1, further comprising an elastic layer between the release layer and the metal layer.   The fixing belt according to claim 2, wherein the elastic layer is formed of a rubber selected from silicone rubber, fluorine rubber, and fluorosilicone rubber.   An image forming apparatus comprising the fixing belt according to claim 1.

Images