JPH08160797A - Thermal fixing roller - Google Patents

Abstract

PURPOSE: To perfectly fix a resistance layer and a base material by forming the resistance layer by firing exothermic resistance paste. CONSTITUTION: A glass pipe stock 1 constituted so that residual compression stress is generated on the outer periferal surface of a glass cylinder is formed by being passed through a rapid quenching process after a tube body is formed by a hot forming method. Next, the dimensional accuracy is adjusted by grinding work processing. Thereafter, the outside surface is roughened 1a by sand-blasting processing. Then, an exothermic resistance pattern 2 is formed on the roughened outside surface by using the low-temperature exothermic resistance paste whose firing temperature is equal to or under a distortion point. The pattern 2 is constituted so that plural belt-like patterns consisting of plural thin belt parts 2b are formed along the outside periphery in parallel with in a longitudinal direction so that the central part 2a becomes thick and both shaft ends gradually become thin. Then, the terminating ends of the thin belt parts 2b are successively connected to an electrode 3. The glass pipe stock 1 is fired after the pattern 2 is formed. Next, th annular electrode 3 is formed on the shaft end side of the pipe stock 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a facsimile,
The present invention relates to a heat fixing roller that is incorporated in an electrophotographic apparatus such as a printer and that thermally fixes an unfixed toner image, and particularly relates to a heat fixing roller formed by using glass as a base.

[0002]

2. Description of the Related Art Conventionally, a heat fixing roller (hereinafter referred to as a heat roller) having a heat source as a means for thermally fixing an unfixed toner image transferred from a photosensitive drum to a recording medium, and a pressure roller coated with a heat resistant resin are provided. The heat roller is configured so as to be capable of rotating synchronously in a pressed state,
The toner image is heat-fixed by inserting the recording medium carrying the unfixed toner image into the nip between the rollers while being heated to around ℃. For this type of heat roller, an indirect heating method is used in which a halogen lamp or an infrared lamp is inserted along the axis of a metal sleeve with good thermal conductivity that is laminated and coated on the surface with an elastic layer or a release layer. However, in the indirect heating method, a wait time of about several minutes is required for the heat roller to rise to the fixing possible temperature range, and it is difficult to quickly raise the temperature and control the temperature.

In order to solve such a drawback, a direct heating system in which the roller base material is made of a conductive ceramic and the roller base material itself is heated is also adopted, but such a ceramic is expensive. In addition, the shaft end surface is in contact with the outside air, and heat conduction from the bearing portion easily causes a sag in the temperature curve in the shaft end direction.

In order to eliminate such drawbacks, a heat-generating resistor layer is formed on the surface of a roller base material having low heat conductivity such as glass, enamel, phenol resin or alumina ceramic, and a Teflon layer is further formed on the heat-generating resistor layer. It proposes a heat roller configured so that Joule heat can be applied to an unfixed toner image by supplying electric power to the resistor layer. (JP-A-1-177577) A method for manufacturing such a heat roller is disclosed in, for example, JP-A-64-86185. The process will be briefly described. First, the surface of the roller base material is appropriately roughened, and then pretreatment such as trichlene washing and pickling is performed, and the electroless plating bath (Ni-W at 80 ° C, PH9) is used.
-P or Ni-Cu-P) to form a heating resistor layer having a thickness of 0.1 to 0.5 μm. Next, a Teflon layer of PFA resin or the like is formed on the surface of the heat generating resistor layer in a thickness of 10 to 40 μm, and the Teflon layer is brought into close contact with the heat generating resistor layer and ring-shaped electrodes are attached to both ends to complete the process.

[0005]

However, glass,
Unlike metal materials, even when enamel, phenolic resin, or alumina ceramics are plated, the plating layer and the base material cannot be completely fixed and peeling easily occurs. Moreover, since the processing temperature of the Teflon layer reaches 400 ° C., the heating resistor layer is crystallized and the sheet resistance is reduced to about half, and crystallization is caused in the heating step during the processing of the Teflon layer. As a result, the resistance layer at that portion changes greatly, so that the overall resistance value varies.

In order to solve the above drawbacks, a technique for stabilizing the resistance value by performing a heat treatment in advance to crystallize the plating film after forming the heating resistor layer and before forming the Teflon layer. Is disclosed in Japanese Patent Laid-Open No. 2-141783. However, even with the above technique, the variation in the resistance value can be eliminated, but the problems such as complete adhesion between the plating layer and the base material and other problems cannot be eliminated.

In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a heat roller, particularly a heat fixing roller, which can completely fix the resistor layer and the base material and can maintain the strength. .

[0008]

According to the present invention, the heating resistor paste (fired thick film material) is fired to form the resistor layer without forming the heating resistor layer by plating as described above. It is a thing.

On the other hand, among the roller base materials disclosed in the above-mentioned prior art, the phenol resin does not have a heat resistant temperature that can withstand firing, and the enamel has a low heat retention property, and especially when the diameter is reduced, it is heated as a roller base material. Lack of functionality. For this reason, it is preferable to use ceramics or glass for the low thermal conductivity roller base material, but ceramics are generally formed by sintering, and for example, a hollow cylindrical body of 15 to 30φ is made into A4 or A3 size. Corresponding to 200-300
It is quite difficult to accurately machine a product with an axial length of mm without causing eccentricity or runout. Therefore, it is preferable to use glass for the roller base material in consideration of material cost, ease of molding, and mass productivity such as workability.

[0010] Among the glasses, a typical so-called heat-resistant glass is fused silica glass, which is expensive. Therefore, it is preferable to use borosilicate glass, aluminosilicate glass (for example, Supremax), Vycor (silica glass similar to quartz glass), etc. (hereinafter, these are referred to as heat resistant glass including quartz glass). However, as a characteristic of the glass, as shown in FIG. 2, the elongation due to the thermal expansion of the glass increases linearly with temperature up to around the annealing temperature, but the so-called transition point Tg (corresponding to the annealing point). ), The thermal expansion occurs with a steep gradient up to the softening point At. Dt is a strain point.

However, the firing temperature at the time of firing using the exothermic resistance paste of Au, Pt, Pd, ruthenium oxide, etc. is 700 to 800 ° C., which greatly exceeds the annealing point (570 ° C.) of borosilicate glass. Therefore, there is a possibility that the heat-generating resistor layer fired may be cracked or cracked due to thermal contraction after firing. Also, when manufacturing a roller base material using heat resistant glass, a residual compressive stress is generated on the outer peripheral surface of the glass cylinder by undergoing a quenching process. However, as described above, if firing is performed at a temperature equal to or higher than the strain point. The so-called annealing process is performed, the residual compressive stress is released, in other words, the strength is reduced, and the glass tube is easily broken by the pressing force of the pressure roller of the fixing device or the pressing force of the paper jam. Become.

In FIG. 3, the strain point is 520 ° C. and the annealing point is 570 ° C.
Shows the relationship between the annealing temperature and the fracture strength of the rapidly cooled borosilicate glass that has generated residual compressive stress through the rapid cooling process (20φ, 1t cylindrical glass). As can be understood from this figure, the strain point is exceeded. And the strength is reduced to about 3/4.

Therefore, the present invention prevents cracks and cracks in the heat-generating resistor layer due to heat shrinkage after firing, and the breaking strength of the quenched heat-resistant glass in which residual compressive stress is generated by the quenching process. In order to prevent deterioration
The heating resistor paste is fired at a firing temperature below the strain point. That is, specifically, the heat resistance paste that can be used is determined by the relationship with the roller base material,
Since quartz glass and Vycor have a strain point of around 1000 ° C., they can be fired using a heating resistance paste such as Au having a firing temperature of 600 ° C. or higher. In the case of borosilicate glass, since the strain point is around 500 to 550 ° C., a low temperature heating resistance paste such as palladium or silver having a firing temperature of 450 to 550 ° C. (for example, a firing temperature of 450 to 5 ° C.).
Firing is preferably performed using Noritake NP-4208) at 00 ° C. Furthermore, aluminosilicate glass (eg Suprema
In x), since the strain point can be set to around 600 ° C., the low temperature heating resistance paste such as silver or platinum having a firing temperature of 500 to 550 ° C. (for example, a firing temperature of 500 to 55).
Baking is preferably performed using Noritake NP-4210) at 0 ° C. The baking thick film material is the baking temperature (for example, 380 ° C.) of the Teflon film and other release materials that are subsequently used.
Higher is desirable. If the baking temperature of the Teflon film is higher than that of the heating element resistance layer, the resistance value of the heating element resistance layer fired at a constant angle is not uniform when baking the Teflon film.

[0014]

[Effect] Therefore, according to the present invention, since the heating resistor paste is fired to form the resistor layer without forming the heating resistor layer by plating, the resistor layer and the base material can be completely fixed. Is. In the present invention, by roughening the surface of the roller base material on which the resistor is formed, the complete fixation of the resistor layer and the base material is further facilitated. The resistor forming surface may be formed on the inner peripheral surface or the outer peripheral surface of the roller base material. Further, although the present invention forms the roller base material using the glass material, since the firing temperature is set to the strain point or lower, it is possible to prevent the heat generating resistor layer from cracking or cracking due to thermal contraction after firing. Even if the quenched and heat-resistant glass is used, its strength does not decrease.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, the dimensions, materials, shapes, relative positions and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely examples, unless otherwise specified. Not too much. A method of manufacturing the heat roller used in the present invention will be described with reference to FIG. The roller base material has a strain point of 520 ° C and an annealing point of 5
When manufacturing a roller base material using borosilicate heat-resistant glass at 70 ° C, a tube having an outer diameter of 20φ, a length of 260 mm, and a wall thickness of 1 t is formed by hot molding, and then a quenching process is performed to obtain a glass cylinder. The glass base tube 1 in which a residual compressive stress is generated is formed on the outer peripheral surface. Next, after adjusting the dimensional accuracy by a grinding process, the outer surface thereof is roughened by sandblasting 1a.

On the roughened outer surface, for example, Noritake NP-4208 having a firing temperature of 450 to 500 ° C. (composition:
As shown in FIG. 1 (A), a heating resistor pattern 2 was formed using a low temperature heating resistor paste of silver). The heating resistor pattern 2 has a strip-shaped pattern composed of a plurality of strip portions 2b in a longitudinal direction along the outer periphery so that the central portion 2a has a thick strip shape and both shaft ends are gradually narrowed. A plurality of thin strips 2b are formed in parallel with each other, and the end portion of the narrow strip 2b is connected to the electrode 3.
Then, after forming the above pattern 2, 450 to 500
Bake at a temperature of ° C.

Next, a ring-shaped electrode 3 is formed on the axial end side of the element tube 1 so as to be connected to the heating resistance pattern 2. The electrode 3 forming means may be formed by vacuum vapor deposition, or a ring-shaped metal sheet body may be attached by adhesion. Alternatively, a low-resistance electrode pattern may be formed continuously with the heating resistance pattern, and may be fired integrally with the heating resistance pattern.

In the present embodiment, the pattern area on both axial end sides of the glass tube is smaller than that of the other regions. However, when a strip-shaped pattern having a uniform width is used, both end portions of the heat roller are The temperature is lower than in other areas, and the uneven heat distribution causes uneven fixing, and curls and wrinkles occur on the recording paper. Therefore, in the present embodiment, the pattern shape as described above is used to prevent the temperature drop at both ends of the roller and to make the heat distribution uniform. Note that, without taking the above-mentioned shape, the resistance value may be changed so that the amount of heat generated by the pattern resistances on both shaft end sides of the substrate is larger than that in other regions, which results in uniform heat distribution. Can be achieved.

After the pattern 2 and the electrode 3 are formed, the electrode portion 3 is masked and the primer 4 is applied.
The primer 4 is diluted with a volatile solvent and thinly coated twice with a film thickness of about 15 μm.

Next, after drying at 70 ° C. for about 5 minutes, the primer 4 is applied again. In addition, this primer 4 painting is 30
Two reciprocations are performed with a film thickness of about μm.

Next, P using powder Teflon made by DuPont
After FA powder electrostatic coating is performed and baking is performed at 380 ° C. for about 40 minutes to form the Teflon film 5, cooling is performed and finish polishing is performed.

The appearance of the heat roller 10 shown in FIG. 1 (B) thus formed did not show any cracks or peeling, and no peeling was observed in the peeling test using cellophane tape. Next, in order to examine the breaking strength, the breaking strength of the glass tube before forming the heating resistor pattern and the breaking strength of the heat roller manufactured in the above process were examined, and both were about 26 to 28 kg. No difference was observed before and after the formation of the heating resistor pattern.

Next, a heating resistance paste having the same composition (silver) as that in the above-mentioned embodiment was used, and the firing temperature was 550 to 60 above the strain point.
After the heating resistor pattern was formed using the heating resistor paste of Noritake NP-4011 at 0 ° C. in the same manner as in the above-mentioned example, the breaking strength of the one on which the primer coating and the Teflon coating were formed was examined and found to be 19 to 21 kg. It was confirmed that the breaking strength was significantly reduced.

Next, in order to confirm the surface roughening effect of the glass tube, a heat roller was manufactured in the same manner as in the above example without sandblasting, and a portion where a primer or pattern peeling occurred was confirmed. did it.

[Brief description of drawings]

FIG. 1 shows a shape of a heat fixing roller according to an embodiment of the present invention, (A) shows a shape of a heating resistor pattern formed on a glass tube during its manufacturing, and (B) shows a completed drawing thereof. The principal part sectional drawing is shown.

FIG. 2 shows a thermal expansion characteristic curve of glass.

FIG. 3 shows the relationship between the temperature and the breaking strength of a glass glass tube made of quenched glass formed by using borosilicate glass.

[Explanation of symbols]

 1 Glass Element Tube 2 Heating Resistor Pattern 3 Electrode 4 Primer 5 Teflon Film 10 Heat Roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display H05B 3/84

Claims (4)

[Claims] 1. A heating resistor layer is formed on the inner or outer peripheral surface of a low thermal conductive roller base material, and a release layer is further formed on the outer peripheral surface of the roller substrate, and electric power is applied to the resistor layer via electrodes. In a heat fixing roller configured to generate Joule heat by supplying, a roller base material is formed of a heat-resistant glass tube, and the heating resistor layer is formed by firing at a temperature not higher than the strain point of the heat-resistant glass. Heat-fixing roller characterized by being formed of a fired thick film material 2. A heating resistor layer is formed on the inner or outer peripheral surface of the low thermal conductive roller base material, and a release layer is further formed on the outer peripheral surface thereof, and electric power is applied to the resistor layer via electrodes. In a heat fixing roller configured to generate Joule heat by supplying, the roller base material is a heat-resistant quenched glass tube, and the heating resistor layer is formed by firing at a temperature not higher than the strain point of the heat-resistant glass. Heat-fixing roller characterized by being formed of a fired thick film material 3. The heat resistant glass is borosilicate glass, aluminosilicate glass, silica glass, quartz glass,
2. The heat fixing roller according to claim 1, wherein the fired thick film material has a firing temperature higher than the firing temperature of the release material and lower than the strain point of the heat resistant glass used for the roller base material. 4. The heat-fixing roller according to claim 1, wherein the roller base material is a heat-resistant glass tube having a surface on which the heating resistor layer is roughened by sandblasting or the like.