JPH0934286A - Fixing belt and fixing device for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic fixing belt for an electrophotographic device which is suitable for use with a belt type fixing device, has high thermal conductivity and high rigidity and has excellent heat resistance, fatigue resistance and long life and a fixing device for the electrophotographic device which utilizes such fixing belt, is small in size, has excellent durability and is enhanced in function. SOLUTION: This endless fixing belt for the electrophotographic device is a fixing belt B which may be cyclically and circumferentially wound by forming a nip part for thermally fixing the unfixed toner image on a recording medium by a pressure between a pressurizing member and there. The fixing belt is formed by using an endless electroforming sheet consisting of a nickel- manganese alloy contg. 0.05 to 0.6wt.% manganese and having micro-Vickers hardness of 450 to 650 as a base body. The fixing device into which the fixing belt is assembled is formable to a smaller size and is highly durable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing belt for pressure-fusing and fixing unfixed toner on a recording medium onto the recording medium, and a fixing device for an electrophotographic apparatus using the fixing belt.

[0002]

2. Description of the Related Art Conventionally, a so-called heating roller system has been widely used for a fixing device for an electrophotographic apparatus. This is because a heating source is provided inside a pair of rollers whose surfaces are coated with a non-adhesive substance, and the recording medium on which the toner is transferred is rotated by applying an appropriate pressure between the rollers to rotate the recording medium. This is a system in which fixing is performed by passing between a pair of rollers. On the other hand, recently, a belt is wound around one of the pair of rollers and a third roller,
A technique has been developed in which the toner on the recording medium is pressed by the belt surface.

Japanese Patent Laid-Open No. 6-318 is one of such techniques.
An example of No. 001 is a fixing device of a belt fixing system as shown in FIG. 2, which includes a fixing roller R ₁ , a pressure roller R ₂ , and
A heating / tensioning roller R ₃ is provided, and a fixing belt B is stretched between the fixing roller R ₁ and the heating / tensioning roller R ₃ . A guide plate G is provided below the lower portion of the fixing belt B with a gap therebetween, while the recording medium D passes through a heating passage P between the lower portion of the fixing belt B and the heated guide plate G. It is configured to be preheated.
As described above, since the recording medium D carrying the unfixed toner image is preheated, the temperature of the nip portion can be set low, so that the releasing property between the fixing belt B and the toner is enhanced, and the clear fixing without offset is performed. An image is obtained.

In the belt fixing type fixing device, the angle between the straight line connecting the center point of the fixing roller, the lower part of the fixing roller and the contact point of the fixing belt with the straight line connecting the contact point and the center point of the pressure roller is 90. An improved technique for obtaining a stable, high-quality fixed image by setting the angle within the range of 0 to 175 ° has already been applied for a patent by the present applicant (Japanese Patent Application No. 7-88357).

[0005]

Also in the fixing device using the belt as described above, the fixing belt having excellent thermal conductivity and high dimensional accuracy is used as in the conventionally known fixing device of the belt fixing system. is necessary. If a fixing belt formed of a heat-resistant polymer material such as polyimide resin is used as the fixing belt, it is difficult to increase the fixing speed due to insufficient thermal conductivity, and the fixing belt may have a steady temperature. Although it takes time, the fixing belt made of metal such as nickel has excellent thermal conductivity and dimensional accuracy, but the strength decreases due to the heat treatment when the release layer is provided on the surface, so the service life is long. Has the disadvantage of being short and impractical.

Therefore, the present invention is intended to improve the above-mentioned drawbacks and to obtain a long-lasting metallic endless fixing belt suitable for use in a belt type fixing device, and further, to provide a high thermal conductivity. To provide a metallic fixing belt for an electrophotographic apparatus, which is excellent in heat resistance and fatigue resistance, and is small in size, excellent in durability and highly functionalized using the fixing belt. Another object of the present invention is to provide a fixing device for an electrophotographic apparatus.

[0007]

A fixing belt for an electrophotographic apparatus according to the present invention forms a nip portion for pressure heat fixing an unfixed toner image on a recording medium between a pressure member and a circulating member. A fixing belt that can be formed by using a nickel-manganese alloy containing 0.05 to 0.6% by weight of manganese and having an endless electro-casting sheet having a micro Vickers hardness of 450 to 650 as a substrate. And

The fixing device for an electrophotographic apparatus of the present invention is
An endless fixing belt is stretched between the fixing roller and the heating roller, and a pressure roller for pressing the fixing roller from below through the fixing belt is provided to form a nip portion between the fixing belt and the pressure roller. Then, in a fixing device in which a recording medium support is provided below the fixing belt between the heating roller and the nip to form a heating passage between the fixing belt and the fixing belt, an electrophotographic apparatus having the above-mentioned configuration as the fixing belt. A fixing belt for the apparatus is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Since the fixing belt for an electrophotographic apparatus of the present invention needs to have an endless shape, its substrate is
An electrolytic bath capable of electrodepositing a nickel-manganese alloy can be used to produce a nickel-manganese alloy, for example, by using a master mold made of stainless steel as a cathode by an electrolytic casting method. As the electrolytic bath in this case, for example, a known nickel electrolytic bath such as a sulfamic acid-based one in which manganese ions are allowed to coexist and an additive such as an appropriate PH adjusting agent, a pit preventing agent, and a brightening agent is used. By controlling the manganese ion concentration, electrolytic bath temperature, cathode current density, etc.,
It is possible to obtain a nickel-manganese alloy battery having a desired manganese content.

Next, after separating the side end portion of such an electric plug body, it is detached from the mother mold, and washing, drying, machining and the like can be carried out to manufacture a substrate having a desired shape and size. Further, the hardness can be adjusted by adding heat treatment as required. In this way, a substrate having a micro Vickers hardness in a desired range, that is, in the range of 450 to 650 can be obtained.
From the viewpoint of the balance of thermal properties such as heat capacity, flexibility, dimensional stability, and mechanical properties such as strength, it is preferably in the range of 20 to 80 μm.

The fixing belt for an electrophotographic apparatus of the present invention is manufactured by further coating a suitable primer or the like on the surface of the above-mentioned substrate and further providing a release layer, and the like. , For example, silicone rubber, fluororubber,
A single layer or multiple layers can be formed by using a material having heat resistance and non-adhesiveness, such as a fluororesin, alone or in combination.

Further, in a fixing device for an electrophotographic apparatus incorporating the fixing belt for an electrophotographic apparatus of the present invention, the fixing belt for an electrophotographic apparatus of the present invention is stretched between a fixing roller and a heating roller, and the fixing belt is provided. A nip portion is formed between the fixing belt and the pressure roller by providing a pressure roller that presses the fixing roller from below through the fixing belt portion. The recording medium is supplied through a heating passage formed between the recording medium support and the recording medium support provided. The fixing belt heated by the heating roller preheats the recording medium carrying the unfixed toner image as it moves toward the fixing roller along the heating passage, and replenishes the heat lost from the fixing roller during image fixing. It also has a function to do.

In the fixing device for an electrophotographic apparatus of the present invention, a straight line passing from the contact start point of the fixing belt below the fixing roller to the center point of the fixing roller, and a straight line passing from the contact start point to the center point of the pressure roller. Between 90 ° and 175 ° on the side opposite the heating roller, preferably 12 °.
When the pressure roller is in pressure contact with the fixing roller as in the range of 5 ° to 160 °, the nip portion faces downward at the nip entrance, so that the unfixed image is carried. The recording medium is bent in a gentle arc shape following the nip on the side separated from the fixing belt in front of the nip entrance. Therefore, it is possible to prevent problems such as the disturbance of the unfixed image and the partial change of the gloss of the image due to the contact of the recording medium being conveyed in the heating passage with the fixing belt.

The fixing belt for an electrophotographic apparatus according to the present invention, which is incorporated in such a fixing device, is subjected to bending stress repeatedly when it circulates between the fixing roller and the heating roller, and therefore is unlikely to cause fatigue. is important. From the viewpoint of thermal conductivity and dimensional stability, it is preferable to use a metallic material, but the pure nickel electrodeposited material has a rough crystal structure and low mechanical strength, so it is a durable material for forming the fixing belt. The sex was not enough. Therefore, when a brightener or the like was added to the electrolytic bath in order to obtain a dense electrodeposited product, the mechanical strength of the electrodeposited product was improved, but the durability was not so improved.

However, the manganese content is 0.05 to
When an endless sheet-like substrate obtained by electroplating a nickel-manganese alloy in the range of 0.6% by weight, particularly one having a micro-Vickers hardness in the range of 450 to 650, is used, the repeated It was found that embrittlement hardly occurs even when bent, and durability is remarkably improved. The micro Vickers hardness and the manganese content are the requirements for providing the mechanical properties required as the base material for the fixing belt, but one of them is not sufficient to achieve the object of the present invention. That is, even if the micro Vickers hardness is within the above range, if the content of manganese is less than 0.05% by weight, the durability improving effect is not remarkable, and if it exceeds 0.6% by weight, the quality of the electrodeposited product is high. Not only varies, but also results in reduced durability, which is not preferable.

The fixing belt for an electrophotographic apparatus of the present invention comprises a silicone rubber, a fluororubber, and a silicone rubber on the surface of a substrate which simultaneously satisfies the above manganese content requirement and hardness requirement.
It can be obtained by providing a release layer made of a material having heat resistance and non-adhesiveness such as fluororesin. Even if the amount of releasing oil such as silicone oil is extremely small, the releasing property with the toner is good, the fixing belt is prevented from being soiled due to the adhesion of the toner, and a clear image without an offset phenomenon is generated. In addition to being obtained, it shows excellent performance that the quality is stable and can withstand long-term use without deterioration.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fixing device for an electrophotographic apparatus of the present invention will be described below in more detail with reference to the accompanying drawings. FIG. 1 shows the entire fixing device according to the present invention. The fixing device includes a fixing roller R ₁ , a pressure roller R _2, and a heating / tensioning roller R ₃ , and a fixing belt B is stretched between the fixing roller R ₁ and the heating / tensioning roller R ₃ .
An oil application roller R ₄ is provided so as to contact the upper portion of the fixing belt B, and a guide plate G is provided below the lower portion of the fixing belt B with a gap between the oil applying roller R ₄ and the lower portion of the fixing belt B. A heating passage P for the recording medium D is formed between the guide plate G and the guide plate G.

Further, the heating / tensioning roller R ₃ is pressed by the pressing lever U in the direction separating from the fixing roller R ₁ , so that a desired tension is applied to the fixing belt B and the fixing roller R 3 is also applied. By being driven by _{1 and} driven by the heating and tension roller R ₃ , the fixing belt B can rotate stably without slipping or loosening.

The fixing roller R ₁ as used in the fixing device is meant to be provided with a silicone rubber heat-resistant elastic layer with a thickness of 3mm on iron core metal having a diameter of 14 mm, also the pressure roller R ₂ also, Similarly, a heat resistant elastic layer of silicone rubber having a thickness of 3 mm is provided on an iron cored bar having a diameter of 14 mm. Although no heat source is provided inside the fixing roller R ₁ and the pressure roller R ₂ , an auxiliary heat source may be provided.

Heating and tension roller R_ThreeHas a diameter of 20
The surface of an aluminum cylindrical cored bar with a thickness of 1.75 mm in mm
It is lumite-treated and has a heating source H inside.
As a result, the light distribution at both ends was increased by 50% from the center.
A W heater is provided. And heating and tensi
Ron R_ThreeThe temperature of the fixing belt B heated by
The thermistor S for controlling is the non-sheet passing of the fixing belt B.
The thermistor S is provided so as to contact the section.
Is heating and tension roller R_ThreeSet so that it touches the surface of
It is also possible to kick. In this example, the heating and
Shorolla R _ThreeAnd fixing roller R₁Distance between axes is 47
It is as mm.

The oil application roller R ₄ has a diameter of 8 mm, a heat-resistant paper layer impregnated with silicone oil, and a 100 μm porous fluororesin film as the outermost layer. Is. The guide plate G is made of iron and has a fluororesin coating on its surface, and is grounded so as not to disturb the unfixed image by static electricity. The guide plate G is almost between the heating / tension roller R ₃ and the fixing roller R _1. At the midpoint position, the gap between the upper surface of the guide plate G and the lower portion of the fixing belt B is set to 3 mm.

Further, the axial position of the fixing roller R ₁ , that is, the central point is C ₁ , the position of the contact start point of the fixing roller R ₁ and the fixing belt B is C ₂ , and the axial position of the pressure roller R ₂ , that is, the central point. was a C _3, when the angle (the side opposite to the heating and tensioning roller) between the straight line C ₂ C ₁ and the line C ₂ C ₃ is defined as theta, the position of the pressing roller R ₂ theta is 90 ° ~ 18
The structure is such that it can be changed within the range of 0 ° (Fig. 1
Shows the case where θ is 140 °).

The fixing belt B used in the fixing device was prepared as follows. According to the formulation of Table 1, an aqueous solution containing nickel sulfamate tetrahydrate (SN), a 50 wt% aqueous solution of manganese sulfamate (SM) and boric acid (BA) was prepared, and a container filled with activated carbon and an electrolytic cell were prepared. After performing electrolytic purification with low current while circulating the liquid between the
Electrolytic baths A to E were prepared by adding a pit inhibitor until the surface tension reached 43 dyne / cm.

[0024]

[Table 1]

An appropriate brightener a is added to each of these electrolytic baths.
~ D was added, and while stirring at a bath temperature of 58 ° C and a pH of 4.3, the rotating stainless steel cylindrical mother die was used as a cathode, and the titanium basket containing nickel pellets was used as an anode. Electrolysis was performed according to the conditions to form a 40 μm-thick electrodeposit on the surface of the matrix. Take these electrodeposits together with the master mold from the electrolytic bath, wash them with water, cut off the ends of the deposits, and then immerse them in water to separate the deposits from the master mold and pull them out thoroughly. It was washed, dried, and cut into a width of 6 mm by machining to obtain endless belt-shaped metal substrates 1 to 10 having a peripheral length of 157 mm.

The hardness of each of these substrates was measured using a micro Vickers hardness tester under the conditions of a test load of 100 gf and a load holding time of 15 seconds, and the manganese content was determined by analyzing the electrodeposits. It was measured. Then, between the driving pulley having a diameter of 10 mm and the driven pulley having the same shape, which has a crown shape with a radius of curvature of 500 mm,
With each of the above-mentioned bases stretched, a driven pulley is loaded and a tension of 1kgf is applied to the base, the drive pulley is rotationally driven at 3650rpm, and the number of rotations of the belt until the base is broken is measured to make it durable. It was sex. The results are summarized in Table 2.

[0027]

[Table 2]

Looking at these results, the manganese content was 0.
Electrolytic base made of nickel-manganese alloy having a micro Vickers hardness of 450 to 650 within a range of 05 to 0.6% by weight has a remarkably long service life until fracture, but has a manganese content or a micro Vickers hardness. It can be seen that if any of the above is out of this range, it is easy to break due to deterioration.

Further, the substrates 2, 5 and
Applying the electroplating conditions created in No. 6 to form electrodeposits with a thickness of 40 μm or 30 μm on the surface of the matrix, respectively, wash and dry them, then machine them to give a width of 230 mm and a perimeter of 15
Four types of endless belt-shaped metal substrates of 7 mm were obtained. Then, after applying a primer to the outer peripheral surfaces of these bases, a silicone rubber layer (S layer) having a thickness of 150 μm is provided and then 200
Heat treatment is performed at 120 ° C. for 120 minutes, or a mixture layer (F layer) of fluororubber and fluororesin having a thickness of 30 μm is provided on the S layer having a thickness of 100 μm and baked at 280 ° C. for 30 minutes, and each fixing belt 11-14 were created. The electroplating conditions, heat treatment conditions, properties and structures of the substrate and the fixing belt of these substrates are as shown in Table 3.

Next, these fixing belts 11 to 14 were assembled into the fixing device according to the present invention, the tension applied to the fixing belt by the pressure lever U was 2.4 kgf, the fixing roller R ₁ and the pressure roller. Durability of the fixing belt is adjusted by adjusting the pressing force applied to the nip between R ₂ to be 20 kgf, and continuously operating until the surface breaks at a fixing belt surface temperature of 166 ° C. and a running speed of 120 mm / sec. I checked (time). The results are also shown in Table 3. In addition,
The Micro Vickers hardness of the fixing belt 11 of the comparative example is
After the durability test, it decreased to about 290 to 350.

[0031]

[Table 3]

[0032]

The fixing belt for an electrophotographic apparatus of the present invention comprises:
Quality is stable, does not easily deteriorate, and has excellent durability.
A fixing device for an electrophotographic apparatus, which incorporates the fixing belt for an electrophotographic apparatus of the present invention, can be downsized and have high functionality, can stably obtain a high quality fixed image for a long period of time, and has high reliability. It was possible to realize the nature.

[Brief description of drawings]

FIG. 1 is a schematic view showing an entire fixing device for an electrophotographic apparatus according to the present invention.

FIG. 2 is a schematic view showing a conventional belt fixing type fixing device for an electrophotographic apparatus.

[Explanation of symbols]

R ₁ fixing roller R ₂ pressure roller R ₃ heating / tensioning roller B fixing belt R ₄ oil applying roller G guide plate D recording medium P heating path U pressing lever H heating source S thermistor C ₁ fixing roller R ₁ center point C ₂ Position of contact start point between fixing roller R ₁ and fixing belt B C ₃ Center point of pressure roller R ₂ θ Angle between straight line C ₂ C ₁ and straight line C ₂ C ₃

Claims (5)

[Claims] 1. A fixing belt capable of forming a nip portion for pressure-heat fixing an unfixed toner image on a recording medium between the pressure member and a circulation belt, and manganese 0.05. A fixing belt for an electrophotographic apparatus, characterized in that an endless electrogalvanized sheet having a micro Vickers hardness of 450 to 650, which is made of a nickel-manganese alloy containing 0.6 to 0.6% by weight, is formed as a base. 2. The fixing belt for an electrophotographic apparatus according to claim 1, wherein a release layer is provided on the surface of the base. 3. An endless fixing belt is stretched between the fixing roller and the heating roller, and a pressure roller for pressing the fixing roller from below via the fixing belt is provided, and the pressure roller is provided between the fixing belt and the pressure roller. A fixing device in which a nip portion is formed, a recording medium support is provided below the fixing belt between the heating roller and the nip, and a heating passage is formed between the heating roller and the fixing belt, and the fixing belt is used as the fixing belt. 1. A fixing device for an electrophotographic apparatus, comprising the fixing belt for an electrophotographic apparatus according to 1. 4. A straight line passing through a center point of the fixing roller from a contact start point below the fixing roller with the fixing belt,
An angle between the contact start point and a straight line passing through the center point of the pressure roller is 90 ° to 1 on the side opposite to the heating roller.
The fixing device for an electrophotographic apparatus according to claim 3, wherein the fixing device is in a range of 75 °. 5. The fixing device for an electrophotographic apparatus according to claim 4, wherein the angle is in the range of 125 ° to 160 °.