JPH09179423A - Thermal fixing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing roller having a metal pipe and a heating element brought into pressure contact with each other, not stuck together, and having an excellent temperature rising effect and durability. SOLUTION: This roller is composed of a metal pipe 1, a heat-resistant insulating layer 2 having a heating element arranged on the inner peripheral face of the metal pipe 1, and a foam resin body 3a formed when a room temperature hardening foam resin material is filled in an intra-pipe space section formed with the heat-resistant insulating layer 2 and the metal pipe 1 and is foamed and hardened. The heat-resistant insulating layer 2 is pressed and fixed in the inner peripheral direction of the metal pipe 1 by the foaming pressure of the foam resin body 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating roller. More specifically, the invention relates to printers, copiers,
The present invention relates to a heat fixing roller used in a heat fixing section of a toner image in an electrophotographic apparatus such as a facsimile.

[0002]

2. Description of the Related Art A toner heat fixing section of an electrophotographic apparatus is provided with a heat fixing roller which heats and presses toner on a toner support to fix the toner on the toner support.

Conventionally, as the heat fixing roller, a lower insulating layer made of silicon rubber or the like is adhered to the inner peripheral surface of a thin metal pipe made of aluminum alloy or the like, a heat generating element is adhered on the lower insulating layer, and further on the heat generating element. There is known a four-layer laminated heat fixing roller including a metal pipe formed by adhering an upper insulating layer made of silicon rubber or the like. JP-A-56-12
6286 discloses such a heat fixing roller.

However, this heat fixing roller has various problems. For example, since the insulating layer is made of silicon rubber or the like, it also acts as a heat insulating layer and the effect of raising the temperature is not sufficient. That is, since the heating element is isolated from the metal pipe by the silicon insulating layer, the heat of the heating element is difficult to be immediately transferred to the metal pipe. In addition, since the heating element and the insulating layer are bonded to each other and the temperature is raised to a high temperature of 150 to 200 ° C., the bonding process is difficult and the bonding reliability is poor.

In such an adhering step, a heat resistant adhesive such as an epoxy type or a thermosetting acrylic type is generally used. It is a very difficult work to paste and attach the heating element to the inner peripheral surface of a thin pipe having an inner diameter of 10 to 20 mm by using the liquid or hot melt sheet-like adhesive described above.
In addition, heat treatment at 150 to 200 ° C. is required after applying uniform pressure from the inside of the pipe to the outside diameter direction. Therefore, the cost of the bonding process is generally high, and it is impossible to expect reliability in bonding.

Furthermore, the adhesive portion between the heating element and the insulating layer is easily peeled off due to thermal expansion when the heating element is heated, and the amount of heat radiation at that portion decreases, causing a temperature rise, and the adhesive portion becomes red-heated and eventually a fire. There is even the danger of.

[0007]

As described above, when the heating element is adhered to the metal pipe, there are various problems in the adhering process or the exfoliation of the heating element from the metal pipe.

The present invention has been made in view of the above problems, and room temperature-curable foamed resin is provided in the internal space left in the metal pipe without adhering the heat-resistant insulating layer having the heating element to the metal pipe. An object of the present invention is to provide a heat fixing roller having a structure in which a heat-resistant insulating layer is pressed against and fixed to a metal pipe from the inside by filling the material and foaming and hardening the foaming pressure.

[0009]

According to the present invention, a metal pipe, a heat-resistant insulating layer having a heating element disposed on the inner peripheral surface of the metal pipe, and a pipe formed by the heat-resistant insulating layer and the metal pipe. It is composed of a foamed resin body formed by filling a room temperature curable foamed resin material in the inner space and foam-curing it, and pressing the heat-resistant insulating layer in the inner peripheral direction of the metal pipe by the foaming pressure of the foamed resin body. Provided is a heat fixing roller characterized by being fixed. In the heat fixing roller described above, a hollow foamed resin layer formed by filling a space in a pipe with a room temperature-curable foamed resin material in a hollow shape and foam-curing the foamed resin layer has a thickness of 1 mm or more. Can be In the heat fixing roller of the present invention, preferably, the foaming ratio of the room temperature curable foamed resin material is 2.
~ 20 times. More preferably, the room temperature curable foamed resin material is a foamable silicone resin. Furthermore, according to the present invention, a heat resistant insulating layer provided with a heating element is arranged on the inner peripheral surface of the metal pipe, and the room temperature curable resin foam material is filled in the pipe inner space formed by the heat resistant insulating layer and the metal pipe, Consists of forming a foamed resin body by foaming and curing,
Provided is a method for manufacturing a heat fixing roller, which comprises pressing a heat-resistant insulating layer toward an inner peripheral direction of a metal pipe by a foaming pressure of a foamed resin body to fix the heat-insulating layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

1 and 2 show an example of the heat fixing roller of the present invention, and FIGS. 3 and 4 show another example of the heat fixing roller of the present invention. In the figure, 1 is a metal pipe made of aluminum alloy or the like, 2 is a heat-resistant insulating layer having a heating element, 3a,
3b represents a foamed resin body, respectively. FIG. 5 shows a state in which the heat resistant insulation layer 2 is arranged on the metal pipe 1, and the remaining space in the pipe is indicated by reference numeral 4.

In the present invention, the heat resistant insulation layer 2 is formed on the inner peripheral surface of the metal pipe 1, and the material thereof is preferably polyimide or aramid. Other polymer materials can be used as the heat resistant insulating layer 2, but polyimide is most suitable in terms of workability, insulating properties and heat resistance. The heat resistant insulating layer 2 may be used as a single layer or may have a structure in which a plurality of layers are laminated. Such a polymer material is formed into a film, and a heating element is fixedly formed thereon so as to obtain a predetermined pattern and resistance. Thus, the heat resistant insulation layer 2 is completed.

Examples of the heating element that can be used in the heat fixing roller of the present invention include nickel-chromium alloy, copper-nickel alloy, tungsten and stainless steel. These metal foils are punched or etched, or the metal is formed into a predetermined shape by a metallizing process such as an ion plating method to obtain a heating element.

The feature of the present invention resides in that the heat resistant insulation layer 2 is pressed and fixed to the inner peripheral surface of the metal pipe 1 by the foamed resin bodies 3a and 3b.

According to the first embodiment of the present invention, the foamed resin body 3a is formed in a solid shape. See FIGS. When the heat resistant insulating layer 2 is arranged on the inner peripheral surface of the metal pipe 1, the pipe inner space portion 4 is left in the metal pipe (FIG. 5). When the room temperature curable resin foam material is filled in the space 4 inside the pipe and both ends of the metal pipe are closed to cause a foam curing reaction, a resin foam body 3a is formed. The foaming pressure generated during this foaming hardening reaction causes the heat resistant insulating layer 2 to pass through the metal pipe 1 from the inside.
It is pressed against the inner peripheral surface of and adheres closely. In this way, the close contact between the heat-resistant insulating layer 2 and the inner peripheral surface of the metal pipe 1 is achieved not by adhesion but by the internal pressure of the foamed resin body 3a.

The room-temperature-curable foamed resin material used in the present invention may be any known foamed resin material, as long as it is a foamed resin material of a type that foams and cures at room temperature (irrespective of heating). Resins are preferred. When a foamable silicone resin is used, it foams and hardens by a catalytic reaction (in the presence of a platinum catalyst) at room temperature.

The foaming and hardening mechanism of the foamable silicone resin does not limit the scope of the present invention in any way, but it is explained as follows.

That is, in the curing reaction, the platinum catalyst promotes the polymerization reaction of the monomer ends ˜Si—CH═CH ₂ and ˜SiH, and ˜Si—CH ₂ —CH ₂ —Si— units are produced and proceed. On the other hand, at the same time as the curing reaction, the platinum catalyst also acts as a catalyst for the reaction of ~ Si-OH groups and ~ SiH in the monomer, and ~ Si-O-Si ~ units are produced, and H ₂ (hydrogen) is generated.
Is released. This hydrogen causes the silicone resin to foam.
Therefore, unlike the heat-type foamable resin, the foamable silicone resin does not need to be used by adding a known foaming agent (for example, OBSH) which generates N ₂ (nitrogen) by heating and has a foaming action.

In the present invention, the room-temperature-curable resin foam material has a foaming ratio of 2 to 20 times, preferably 5 to 10 times. If the expansion ratio is less than 2 times, the heat capacity of the foamed resin body to be formed becomes large, the heat energy of the heating element is consumed, and the temperature rising speed of the heat fixing roller becomes slow. On the other hand, if the expansion ratio exceeds 20 times, the strength of the foamed resin body will decrease, and the pipe pressing force will not be satisfactory. Therefore, by setting the expansion ratio of the foamed resin body within the above range (in particular, 5 to 10 times), a foamed resin body having sufficient pressing force can be obtained.

According to the second embodiment of the present invention, the foamed resin body 3b is formed in a hollow shape. See FIGS. 3 and 4.
Foamed resin body 3b is obtained in the same manner as foamed resin body 3a according to the first embodiment, but in this case, heat resistant insulating layer 2 is used.
Pipe inner space 4 left in the metal pipe 1 in which the
A rod-shaped object (round bar) is placed in the space between the rod-shaped object and the heat-resistant insulating layer 2, and room temperature curable foamed resin is filled in, and both ends of the metal pipe are closed to foam at room temperature. When the rod-shaped material is removed after the foaming and curing reaction is completed, a hollow foamed resin body 3b is formed in close contact with the heat-resistant insulating layer 2. Similar to the first embodiment, the foamed resin body 3b presses the heat resistant insulation layer 2 against the inner peripheral surface of the metal pipe 1.

The foamed resin material used as the material of the foamed resin body 3b is exactly the same as the material of the foamed resin body 3a according to the first embodiment of the present invention. Therefore, the preferable expansion ratio also matches the above-mentioned set range.
The foamed resin body 3b is hollow, but the layer thickness is 1 m.
m or more. If the layer thickness is less than 1 mm, the strength of the obtained foamed resin body will be low, and the required pressing force cannot be obtained.

Since the foamed resin material used in the present invention has a room temperature curability, there is almost no shrinkage after the foaming curing reaction.
Therefore, since the shrinkage after the foaming and curing reaction that is observed when the heat-curable foamed resin is used as the foamed resin body is not experienced, the pressing force by the foaming that acts on the heat resistant insulating layer 2 from inside the metal pipe 1 is not attenuated. Sufficient tight fixation is maintained. In the heat fixing roller of the present invention having such a configuration, the heating element (that is, the heat-resistant insulating layer 2 including the heating element) is pressed against the inner peripheral surface of the metal pipe 1 by the foaming pressure of the foamed resin body 3a or 3b. The adhesion to the inner peripheral surface is greatly improved.

[0023]

The following examples serve to illustrate the invention in more detail by means of examples and comparative examples, which do not limit the scope of the invention.

Example 1 A sheet-shaped heating element (heat-resistant insulating layer having a heating element) formed on one surface of a polyimide film (25 μm) with a stainless foil (30 μm) so as to obtain a predetermined pattern and resistance, an outer diameter of 20 mm, The aluminum alloy pipe having an inner diameter of 18 mm was rolled and arranged on the inner peripheral portion. Addition-crosslinking type liquid silicone foam resin (RTV foam silicon, foaming ratio 10 times, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the internal space of the remaining aluminum alloy pipe.
About 1/8 of the volume of the internal space was filled, both ends of the aluminum alloy pipe were sealed and foamed, and crosslinked and integrated to form a foamed resin body, and a heat fixing roller was manufactured.

Although the expandable silicone used in this example is an addition-crosslinking type, it is also possible to use a condensation type silicone foam resin. However, in the latter case, the strength is inferior to that of the addition-crosslinking type foamed silicone.

Example 2 According to the manufacturing method of Example 1, a sheet-shaped heating element was arranged on the inner peripheral portion of the aluminum alloy pipe, and a round bar having an outer diameter of 12 mm was provided near the center of the internal space of the remaining aluminum alloy pipe. Was placed. The void left by inserting the round bar was filled with the same addition-crosslinking type liquid silicone foam resin as used in Example 1 about 1/8 of the void volume, and both ends of the aluminum alloy pipe were sealed to foam and crosslink. They were integrated to form a foamed resin body. After the foam-hardening reaction was completed, the round bar was pulled out to leave the hollow foamed resin body layer in the alloy pipe to manufacture a heat fixing roller. The hollow foamed resin body layer thus obtained had a thickness of about 3 mm.

Comparative Example 1 In Example 2, a millable type silicone foam resin was used instead of the addition cross-linking type liquid silicone foam resin to have a void volume of about 1%.
/ 3 filling, further insert a round bar with an outer diameter of 12 mm, seal both ends of the aluminum alloy pipe, 2 aluminum alloy pipe
It was placed in an oven at 00 ° C. and heat-foamed to form a foamed resin body. Then, the aluminum alloy pipe was cooled and the round bar was removed. In this way, a heat fixing roller in which the hollow foamed resin body was placed inside the aluminum alloy pipe was obtained.

Comparative Example 2 An epoxy adhesive (YEF-040, manufactured by Mitsubishi Petrochemical Co., Ltd.) sheet was inserted between an aluminum alloy pipe having an outer diameter of 20 mm and an inner diameter of 18 mm and the film heating element used in Example 1. After pressurizing with an air bag from the inside at a pressure of 5 kg / cm ² , heat treatment was carried out at 200 ° C. for 1 hour to bond them. After the heat treatment was completed, the air bag was removed from the aluminum alloy pipe to manufacture a heat fixing roller.

Temperature Rise Test A temperature rise test of the heating and fixing rollers of the examples and comparative examples was carried out. Table 1 shows the results in which the temperature rising rate of the heat fixing roller of Example 1 was set to 1 and the temperature rising rates of the other rollers were represented by relative ratios.

Durability Test The above temperature rise test was conducted on the heat fixing rollers obtained in Examples and Comparative Examples, and after each roller reached a predetermined temperature, each roller was kept at that temperature to test the durability of the roller. did. When the life of the heat fixing roller of Example 1 is 100,
The results of the relative ratios of the lives of the other rollers are shown in Table 1.
The life was determined to be the life when it was judged that there was a large amount of blistering peeling between the aluminum alloy pipe and the film heating element, and red heat at the peeling portion was recognized, which was dangerous.

Heater pull-out test After completion of the temperature rise test, the force required at that time for pulling out the film-like heat-generating body from each roller was measured for each roller, and the value for the roller of Example 1 was set to 100, and other rollers were used. Table 1 shows the results of the relative ratios of the pulling forces of the above.

When the heat fixing roller of Comparative Example 2 was subjected to this test, the film-shaped heating element broke, and the pulling force could not be accurately measured.

The performed calculations of the production cost in the production of the rollers for heating the fixing roller in the manufacturing cost Examples and Comparative Examples, the results are also shown in Table 1.

[0034]

[Table 1]

[0035]

As described above, in the heat fixing roller of the present invention, the metal pipe and the heating element are not adhered to each other, and the heat resistant insulating layer having the heating element is provided by the physical pressure bonding force of the foamed resin inside the metal pipe. Since the structure is pressed against the inner peripheral surface, the reliability of fixation between the heating element and the metal pipe is high.

Further, since the heating element is not adhered to the metal pipe, the adhesive portion is not peeled off and the red heat of the heating element and the risk of fire are not seen in the heat fixing roller of the present invention.

According to the present invention, due to the above configuration, the rise of temperature upon heating is faster than that of the conventional heat fixing roller.

In addition, according to the present invention, since the room-temperature-curable foamed resin material is cured and molded as a foamed resin body, shrinkage of the foamed resin body after curing is not observed, and the pressing force against a change in temperature. It is constant and will not be damaged even if it is used for a long time.

In addition, when a foaming resin material having a foaming ratio of 2 to 20 (particularly 5 to 10) times is used in the heat fixing roller of the present invention, the heat capacity of the foaming resin body is small and the heat energy generated by the heating element is consumed. Is smaller, the temperature rises faster.

According to the present invention, an adhesive treatment step is not required when manufacturing the heat fixing roller, so that the manufacturing cost is very low.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a heat fixing roller of the present invention.

FIG. 2 is a vertical sectional view of the heat fixing roller of FIG.

FIG. 3 is a cross-sectional view of another example of the heat fixing roller of the present invention.

FIG. 4 is a vertical sectional view of the heat fixing roller of FIG.

FIG. 5 is a vertical cross-sectional view showing a state where a heat resistant insulating layer is arranged on a metal pipe.

[Explanation of symbols]

 1 Metal Pipe 2 Heat Resistant Insulation Layer 3a, 3b Foamed Resin Body 4 Pipe Internal Space

Claims (4)

[Claims] 1. A metal pipe, a heat-resistant insulating layer having a heating element arranged on an inner peripheral surface of the metal pipe, and a room temperature curable resin foam material in a pipe inner space formed by the heat-resistant insulating layer and the metal pipe. And a foamed resin body formed by foaming and hardening the foamed resin body, and the heat-resistant insulating layer is pressed and fixed in the inner circumferential direction of the metal pipe by the foaming pressure of the foamed resin body to fix the heat-fixing roller. . 2. The hollow foamed resin body layer formed by filling a room-temperature-curable foamed resin material in a hollow space in the pipe and foam-curing the foamed resin body layer has a thickness of 1 mm or more. Heat fixing roller. 3. The foaming ratio of the room temperature curable resin foam material is 2 to.
The heat-fixing roller according to claim 1 or 2, which is 20 times in number. 4. The heat fixing roller according to claim 1, wherein the room temperature curable foam resin material is a foam silicone resin.