JP2002148988A - Heating device, image forming apparatus, and method for manufacturing silicone rubber sponge and roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device using a pressure roller which can effectively use the heat from a heating means because of low heat conductivity and increase the nip width formed between the heating means and the pressure roller because of small hardness. SOLUTION: This heating device is equipped with the pressure roller having an elastic layer having dispersed gap parts formed of resin microballoons.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus, an image forming apparatus, a method for producing a silicone rubber sponge, and a pressure roller for an image heating apparatus of an electrophotographic image forming apparatus such as a copying machine or a laser beam printer. Method for producing silicone rubber sponge roller.

[0002]

2. Description of the Related Art A heating device is used to fix an unfixed image on a recording material used in an image forming apparatus, and a heating device for heating a recording material to improve surface properties such as gloss. It has been widely used as an image heating device, a heat treatment device for drying or laminating a material to be heated, and the like.

A conventional heating device will be described below by taking a heating and fixing device provided in an image forming apparatus such as an electrophotographic copying machine or a printer as an example.

[0004] The heat fixing device of the image forming apparatus includes a recording material (transfer sheet, electrostatic recording paper, electrofax paper,
An unfixed image (toner image) corresponding to target image information formed and carried on a printing paper or the like by a transfer method or a direct method is thermally fixed as a permanently fixed image on a recording material surface. The heat fixing device forms a press contact nip portion (fixing nip portion) such that a heating unit and a pressurizing unit oppose each other, as in a heat roller system or a film heating system, and an image should be fixed in the press contact nip portion. 2. Description of the Related Art A contact heating type device for introducing a recording material and nipping and conveying the same to fix an unfixed image on the surface of the recording material by heat and pressure is often used. Hereinafter, these heating methods will be described.

A) Heat roller system A parallel pressure roller pair consisting of a heating roller (fixing roller) as a heating means and an elastic pressure roller as a pressing means pressed against the heating roller has a basic configuration. The roller pair is rotated to introduce a recording material to be image-fixed into the press-contact nip portion of the roller pair, and to convey the sheet, and the unfixed image is formed on the recording material surface by the heat of the heating roller and the pressing force of the press-contact nip portion. Is fixed by heat and pressure.

B) Film heating method Regarding the film heating method, see JP-A-63-31318.
No. 2, JP-A-2-1577878, JP-A-4-15778
JP-A-44075, JP-A-4-44083, JP-A-4-204980 and JP-A-4-204984
Has been proposed. The film heating method has a heating element and a heat-resistant film (fixing film) as heating means, and has an elastic pressure roller as pressure means. The heat-resistant film is pressed against the heating body by an elastic pressure roller to form a pressure-contact nip, and the heat-resistant film is brought into close contact with the heating body at the pressure-contact nip and slid and conveyed. A recording material to be fixed with an image is introduced between the pressure roller and the recording material, and the recording material is transported together with the heat-resistant film. At this time, the unfixed image is heat-pressure fixed on the surface of the recording material by the heat applied from the heating body to the recording material via the heat-resistant film and the pressing force at the pressure nip. The recording material is separated from the heat-resistant film after passing through the pressure nip.

A film heating type heating apparatus uses a linear heating element having a low heat capacity as a heating element and a thin film having a low heat capacity as a heat-resistant film. Startability) can be improved. Further, in the heating device of the film heating system, using an endless film as a heat-resistant film, as a rotation drive system of the film, a drive roller is provided on the inner peripheral surface side of the film, a method of rotating while applying tension to the film, There is a system in which the film is loosely fitted to the film guide, and the film is driven and driven relative to the pressing rotator by driving the pressing rotator as a pressing means, but since the number of parts can be reduced, In many cases, the latter pressure rotating body driving method is adopted.

As in the above-described heat roller type or film heating type heat fixing device, a heating means and a pressure roller are opposed to each other to form a pressure contact nip portion as a heated material heating portion, and the pressure contact nip portion is formed in the pressure contact nip portion. In a heating device that heats and pressurizes the material to be heated by introducing and transporting the material to be heated, the pressure roller has elasticity in order to increase the speed of the device and reduce the wait time. By increasing the width of the pressure contact nip formed between the heating means due to its elastic deformation, take time to give sufficient heat to the material to be heated, and improve the efficiency of applying heat to the material to be heated. Is also good. However, simply increasing the width of the press-contact nip increases the size of the heating device itself, and at the same time increases power consumption. Therefore, the size and cost of the device can be reduced,
In order to reduce power consumption, it is necessary to further improve the thermal efficiency of the device.

From the viewpoint of improving the thermal efficiency of the apparatus, the amount of heat taken from the heating means to the pressure means cannot be ignored.
Therefore, it is desired to reduce the heat capacity of the pressurizing means in order to increase the speed of the apparatus and reduce the power consumption. As means for reducing the heat capacity of such a pressurizing means, for example, Japanese Patent Application Laid-Open No. 9-11428
In Japanese Patent Application Publication No. 1 (1993), a method of manufacturing a pressurizing rotary body having excellent heat insulation properties by obtaining a pressurizing body having excellent heat insulation properties by incorporating a hollow filler inside an elastic layer of a pressurizing roller as a pressurizing means. It is known that can be.

However, hollow fillers such as hollow silica, alumina, glass and glass fiber are used as the hollow filler, but such inorganic fillers have hollow fillers. When used, since the filler is hard, there is a problem that a large pressing force is required to make the elastic layer of the pressure roller hard and increase the fixing nip width.

Further, in the heating apparatus of the electrophotographic image forming apparatus, in recent years, the size of the apparatus has been reduced, and the diameter of a pressure roller used therein has also been reduced. In order to secure a nip width at the time of fixing by reducing the diameter of the pressure roller, the elastic layer covering the outer periphery of the core metal of the pressure roller tends to have a low hardness. For example, it is disclosed in Japanese Patent Publication No. 4-77315. As described above, those using a foamed elastic body (sponge rubber) for the elastic layer have been put to practical use. However, when the foaming agent mixed in the silicone rubber foams by heating,
The foaming pressure breaks the silicone rubber wall to expose the foam cell, or the silicone rubber wall separating the foam cell and the atmosphere becomes extremely thin, forming a virtual recess. Further, when silicone rubber is foamed in a mold, the foaming pressure is directed to an irregular direction, so that irregular foaming stress is generated in the rubber. Then, when the silicone rubber is taken out of the mold after foaming, the irregular foaming stress is released, and irregularities are generated on the rubber surface.

When such a foamed silicone rubber roller is used as a pressure roller, the molten toner offset to the heating roller or the heating film is transferred to the exposed foam cells or the concave portions of the pressure roller, and the pressure roller becomes dirty. Is generated.

Further, a sponge elastic body as a foamed elastic body formed by foaming silicone rubber is formed on a cored bar, and a heat-resistant release layer of a fluororesin such as PFA or PTFE is formed on the outer peripheral surface thereof by coating. In this case, the coating agent penetrates into the exposed foam cells and the concave portions, and it is difficult to form a smooth and uniform thickness release layer on the surface. Also, when the release layer is formed by covering the fluororesin tube, the fluororesin tube becomes uneven in a foamed cell in a pressurized state. There is a problem that the pressure roller is stained with toner on the back of the paper or the like.

The pressure roller used in the heat fixing device is
It is required that the hardness and the thermal conductivity do not change depending on the heating history over a long time. This is because if the hardness fluctuates, the nip width changes, and if the thermal conductivity increases, the fixing efficiency decreases, all of which affect the fixing performance.

[0015] As one of the methods for producing sponge rubber, a method utilizing resin microballoons is known. One of them is to mix unexpanded microballoons in rubber as described in JP-A-8-128888 and JP-A-5-209080 and heat them to simultaneously expand the resin microballoons and cure the rubber. It is.

As another method for producing a sponge rubber for solving the problems (non-uniform cells) in the above method, a pre-expanded resin microballoon is mixed into a liquid compound, and the resin is melted at a temperature below the resin melting temperature. A method of obtaining a crosslinked rubber molded article and a transfer drum manufactured by the method (Japanese Patent Application Laid-Open No. 10-060151) have been proposed.

Pre-expanded resin microballoons are used as fillers in various paints and plastic materials, but they are easily scattered, so a scattering prevention method has been proposed. For example, in Japanese Patent Application No. 02822142, after mixing an unexpanded resin microballoon and a wetting agent (plasticizer) at or below the expansion start temperature of the unexpanded resin microballoon, the mixture is heated to near the expansion start temperature of the unexpanded resin microballoon. A method for obtaining expanded resin microballoons is disclosed. JP-A-06-240040 discloses that inorganic fine particles are fixed via a binder resin to the surface of a microballoon formed by heating and expanding a thermoplastic resin microcapsule containing a low-boiling organic solvent. A method for producing a microballoon excellent in handleability with less scattering characteristics is disclosed.

However, in the method for producing a silicone rubber sponge containing a resin microballoon which has been expanded in advance, the specific gravity of the expanded resin microballoon is extremely low, the storage form is very bulky, and it is very difficult to mix the silicone resin into the silicone rubber material. There is such a problem. After mixing the conventional unexpanded resin microballoon and the wetting agent (plasticizer) below the expansion start temperature of the unexpanded resin microballoon, the mixture is heated to near the expansion start temperature of the unexpanded resin microballoon to expand the expanded resin microballoon. In the method for obtaining the balloon, phthalate ester plasticizers, aliphatic dibasic ester ester plasticizers, and epoxy plasticizers are exemplified as the wetting agent (plasticizer), but these have poor compatibility with liquid silicone. When the expanded resin microballoons treated with these are mixed with liquid silicone, there may be a problem in storage stability such as separation.

In addition, microballoons having inorganic particles fixed on the surface thereof via a binder resin and having low scattering properties and excellent handleability may not be able to provide sufficient heat insulating properties.

Therefore, when an already expanded resin microballoon is used as a filler, there is a demand for a method that does not use a wetting agent or inorganic fine particles.

[0021]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low thermal conductivity, making it difficult to remove heat from the heating means.
Further, an object of the present invention is to provide a heating device using a pressure roller capable of increasing the fixing nip width with a low surface hardness of the pressure roller and an image forming apparatus including the heating device as a heat fixing device.

A second object of the present invention is to provide a heating device in which the toner of the pressure roller is hardly stained by toner.

A third object of the present invention is to provide a method for producing a silicone rubber sponge and a silicone rubber sponge roller using a resin microballoon without affecting the thermal conductivity (heat insulation) of the produced silicone rubber. The present invention provides a manufacturing method for preventing scattering of resin microballoons.

It is a fourth object of the present invention to provide a method for manufacturing a pressure roller used in a heat fixing device, which receives a heat history and does not change its hardness and thermal conductivity.

[0025]

According to a first aspect of the present invention, there is provided a heating means for heating a sheet-like material to be heated, and a pressure roller disposed opposite to the heating means and pressed against the heating means. In a heating device that heats the material to be heated by introducing and heating the material to be heated to the pressure contact nip portion between the heating means and the pressure roller, the pressure roller is formed by a resin microballoon. A heating device having an elastic layer containing dispersed void portions.

The voids dispersed and contained in the elastic layer of the pressure roller used in the heating device of the present invention are formed by resin microballoons. Since the resin microballoon is an organic filler, it is softer than the inorganic filler and does not excessively harden the elastic layer, so that a sufficient fixing nip width can be formed with a light pressing force.

Further, since the resin microballoon is an organic filler, its thermal conductivity is lower than that of an inorganic filler, so that the resin microballoon has a desirable thermal conductivity of 0.146 W / m · K or less as an elastic layer. It is advantageous.

The resin microballoon is a microballoon whose shell is formed of resin and gas is confined inside. Therefore, the resin microballoon does not form a cell exposed on the surface of the elastic layer, and does not form a concave portion on the surface of the elastic layer. In addition, after mixing the unexpanded resin microballoon with the elastic material, the volatile substance contained in the unexpanded resin microballoon is heated and expanded to form an elastic layer containing the resin microballoon dispersed therein. In addition, since the expansion pressure of the volatile substance is suppressed by the shell, no cells or recesses exposed on the surface of the elastic layer are formed. Therefore, a pressure roller that is not contaminated with toner can be provided.

Further, a second invention provides a step of heating and expanding an unexpanded resin microballoon wet-treated with silicone oil, a step of mixing the thermally expanded resin microballoon with a liquid silicone rubber material, and a step of liquid silicone rubber. And a step of heating and curing the silicone rubber sponge.

In the method for producing a silicone rubber sponge according to the present invention, when the unexpanded resin microballoon is wetted with silicone oil and then heated and expanded at an appropriate temperature, the surface of the expanded resin microballoon becomes a fine silicone oil. The balloons are easily adhered to each other to prevent scattering. Also, since silicone oil is a material equivalent to silicone rubber, it does not substantially affect the thermal conductivity of the silicone rubber sponge to be manufactured.

In the third invention, the step of heating and expanding the unexpanded resin microballoon, the step of mixing the resin microballoon expanded by heating with the liquid silicone rubber material, and the step of heating the mixture on a cored bar Then, the step of curing the liquid silicone rubber, and after heating and curing of the liquid silicone rubber, heating the resin microballoon to an expansion start temperature or higher to break the resin microballoon shape of the shell of the resin microballoon, more preferably. Is a method of manufacturing a roller, comprising a step of forming a release layer on the surface after breaking the microballoon shape of the resin.
The roller manufactured in this manner is a pressure roller using a resin microballoon having insufficient high-temperature heat resistance, that is, a heating unit that heats a recording material carrying an unfixed image to fix the unfixed image, It is particularly effective as a pressure roller that is arranged to face the heating means and is pressed against the heating means to form a pressure contact nip.

That is, when a thermoplastic resin is used for the shell as a non-expandable resin microballoon and a powder containing a substance having volatility is employed, the heat-expanded resin microballoon remains in the silicone rubber sponge as it is. In the elastic layer dispersed in the thermoplastic resin, the thermoplastic resin is harder than the silicone rubber, so that the elastic layer is hardened. If the shell of the plastic resin is broken, pyrolyzed or carbonized, the hardness due to the presence of the shell is lost, and the roller hardness decreases or the thermal conductivity increases, resulting in fluctuations in the fixing performance. May come. When used as a pressure roller for heating and fixing, such shell breakage is apt to occur due to the so-called non-paper-passing portion temperature rise, that is, the resin microballoon is thermally damaged in the non-paper-passing portion and locally has a roller hardness. And the problem may arise in the transportability. When small-size paper is continuously passed, the non-paper passing area of the pressure roller is directly and continuously heated by the fixing member. Therefore, the paper passing area on the surface of the pressure roller is maintained at 150 ° C. or less. However, the surface temperature of the non-sheet passing area may reach about 250 ° C. in some cases.

Therefore, in the present invention, such a problem can be solved by breaking the resin microballoon-shaped shell. Further, the destruction of the resin microballoon-shaped shell may be performed before or after forming the release layer on the surface, or at the same time as the formation, but after the release layer is formed, the resin microballoon-shaped shell is removed. When the resin is broken, the gas components generated by the destruction of the resin are confined, and depending on the type of the destructed resin, the silicone rubber may be degraded. Most preferably, the shape is broken.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus of the present embodiment is a laser printer using a transfer type electrophotographic process.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as an image carrier, and an arrow a
At a predetermined peripheral speed (process speed) in the clockwise direction. The photosensitive drum 1 has a structure in which a photosensitive material layer of OPC, amorphous Se, amorphous Si, or the like is formed on the outer peripheral surface of a cylinder (drum) -shaped conductive substrate such as aluminum or nickel.

The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a charging roller 2 as a charging means during its rotation. A laser beam output from the laser beam scanner 3 to the uniformly charged surface of the rotating photosensitive drum 1 and subjected to modulation control (ON / OFF control) corresponding to a time-series electric digital pixel signal of target image information. By performing the scanning exposure L, an electrostatic latent image of target image information is formed on the rotating photosensitive drum surface.

The latent image formed is developed by the developing device 4 with the toner T and visualized. As a development method, a jumping development method, a two-component development method, an FEED development method, or the like is used, and a combination of image exposure and reversal development is often used.

On the other hand, the transfer material P as the recording material accommodated in the paper feed cassette 9 is fed out one by one by the driving of the paper feed roller 8, and is exposed through a sheet path having a guide 10 and a registration roller 11. The toner image is fed to a transfer nip portion, which is a pressure contact portion between the drum 1 and the transfer roller 5, at a predetermined control timing, and the toner image on the photosensitive drum 1 surface side is sequentially transferred to the surface of the fed transfer material P.

The transfer material coming out of the transfer nip portion is sequentially separated from the surface of the rotary photosensitive drum 1 and introduced into a heating and fixing device 6 as a heating device by a transport device 12 to undergo a heat fixing process of a toner image. The heat fixing device 6 will be described in detail in the following section (2).

The transfer material exiting from the heat fixing device 6 is printed out on a paper discharge tray 16 through a sheet path having a conveying roller 13, a guide 14, and a paper discharge roller 15.

After the transfer material is separated, the surface of the rotating photosensitive drum is cleaned by a cleaning device 7 to remove adhered contaminants such as untransferred toner, and is repeatedly used for image formation.

(2) Heat Fixing Apparatus 6 FIG. 2 is a schematic structural model diagram of the heating fixing apparatus 6 as the heating apparatus used in this embodiment. The heat fixing device 6 of the present example is disclosed in JP-A-4-44075-44083 and JP-A-4-2049.
It is a so-called tensionless type film heating type / pressurizing rotating body (pressing roller) driving type heating device described in JP-A-80-204984.

Reference numeral 21 denotes a substantially semi-arc-shaped, gutter-shaped cross section, and a horizontally long film guide member (stay) having a length in a direction perpendicular to the paper surface. Reference numeral 22 denotes a substantially central portion of the lower surface of the film guide member 21 along the length. The horizontally elongated heating element 23 housed and held in the groove formed as described above is an endless belt-shaped (cylindrical) heat-resistant film loosely fitted to the film guide member 21 with the heating element. These 21 to 23 are heating means side members.

Reference numeral 24 denotes a heating element 22 with a film 23 interposed therebetween.
Is an elastic pressure roller as pressure means pressed against the lower surface of the roller. N is a press-contact nip (fixing nip) formed between the heating roller 22 and the heating roller 22 by elastic deformation of the elastic layer 24 b of the pressure roller 24 pressed against the heating element 22 with the film 23 interposed therebetween. The driving force of the driving source M is transmitted to the pressure roller 24 via a power transmission mechanism such as a gear (not shown), and the pressure roller 24 is driven to rotate at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow b.

The film guide member 21 is made of, for example, PP
It is a molded article of a heat-resistant resin such as S (polyphenylene sulfite) or a liquid crystal polymer.

In this embodiment, the heating element 22 is made of a horizontally long and thin plate-like heater substrate 22a made of alumina or the like, and a linear or strip-shaped Ag formed on the surface side (film sliding surface side) thereof along its length. / Pb or other conductive heating element (resistance heating element) 22
b, thin surface protection layer 22c such as a glass layer, heater substrate 2
Temperature detecting element 22d such as a thermistor disposed on the back side of 2a
It is a ceramic heater having a low heat capacity as a whole.
The temperature of the ceramic heater 22 is quickly raised by supplying power to the energizing heating element 22b, and is adjusted to a predetermined fixing temperature by a power control system including a temperature detecting element 22d.

The heat-resistant film 23 has a total thickness of 100 μm or less, preferably 60 μm or less and 20 μm in order to reduce the heat capacity and improve the quick start of the apparatus.
m or more, a single-layer film such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkylvinyl ether), PPS, or polyimide / polyamide having heat resistance, release property, strength, durability, etc. Composite layer film, etc. in which PTFE, PFA, FEP (tetrafluoroethylene-perfluoroalkylvinyl ether), etc. are coated as a release layer on the surface of a base film such as imide, PEEK (polyetheretherketone), PES (polyethersulfone) It is.

The pressure roller 24 comprises a core metal 24a such as iron or aluminum, an elastic layer 24b filled with a hollow filler 24c, and a release layer 24d. The pressure roller 24 will be described in detail in the next section (3).

When the pressure roller 24 is driven to rotate at least at the time of image formation, the rotation of the pressure roller 24 causes the friction between the pressure roller 24 and the outer surface of the film 23 at the press-contact nip N. A rotational force acts on the film 23 by the force, and the inner surface of the film slides in the press-contact nip portion N in close contact with the lower surface, which is the surface of the heating element 22, and moves around the outer periphery of the film guide member 21 in a clockwise direction of arrow a. , That is, the peripheral speed of the transfer material p carrying the unfixed toner image 搬 送 conveyed from the image transfer unit side, and is rotated without wrinkles. In this case, a lubricant such as heat-resistant grease may be interposed between the inner surface of the film 23 and the lower surface of the heating element on which the film 23 slides in order to reduce the sliding resistance.

When the film 23 is rotated by the rotation of the pressure roller 24 and the temperature of the heating body 22 is raised to a predetermined fixing temperature and the temperature is controlled, the pressure roller 24 of the pressure contact nip portion N A transfer material P as a heated material having an unfixed toner image の 間 に between the film 23 and the film 23 is introduced with the toner image carrying surface side of the film 23 side, and adheres to the outer surface of the film at the press-contact nip portion N. The heat of the heating element 22 is applied through the film 23 and the unfixed toner image Τ is transferred to the transfer material P by the pressure of the pressure nip N. Heat and pressure fixed on the surface. The transfer material P that has passed through the pressure nip N is separated from the outer surface of the film 23 and transported.

A film heating type apparatus 6 as in this example
The heating element 22 having a small heat capacity and a fast temperature rise can be used, and the time required for the heating element 6 to reach a predetermined temperature can be greatly reduced. Since the temperature can be easily raised to a high temperature even from normal temperature, there is no need to perform standby temperature control when the apparatus is in a standby state during non-printing, and power can be saved.

Further, since substantially no tension acts on the rotating film 23 except for the press-contact nip portion N,
Film guide member 21 of film 23 in a rotating state
The moving force along the length of the is small. Therefore, as a means for restricting the movement toward the film, it is sufficient to dispose a flange member which simply receives the end of the film 23, and there is an advantage that the apparatus can be simplified.

(3) Pressure Roller 24 As described above, the pressure roller 24 as the pressure rotating body in the heat fixing device 6 has the core metal 24a and the elastic layer 24b filled with the resin microballoon 24c. are doing.

The pressure roller 24 has an elastic layer and a release layer formed on the outermost surface and made of fluororesin or fluororubber. By setting the thermal conductivity of the elastic layer 24b of the pressure roller 24 within the above range, the amount of heat taken by the heating body 22 from the pressure roller 24 during operation of the heat fixing device 6 can be reduced. For this reason, the temperature rise on the surface of the film 23 can be improved, and quick start of the heat fixing device 6 can be performed. This thermal conductivity is preferably 0.146 W / m · K or less.
If the pressure is lower than 0.084 W / m · K, the temperature rise speed of the pressure roller 24 is increased and the fixing property is improved, but the temperature rise of the non-sheet passing portion when a small size sheet is passed is large. Therefore, the heat resistance of the pressure roller is required.

The thermal conductivity of the elastic layer is measured by a surface thermal conductivity meter (trade name: QTM-500, manufactured by Kyoto Electronics Co., Ltd.). That is, a sensor probe (model: PD-11, manufactured by Kyoto Electronics Co., Ltd.) of a surface thermal conductivity meter is brought into contact with the surface of the elastic layer of the pressure roller in parallel with the axial direction of the pressure roller, and the elastic layer is contacted. Is measured.

The surface roughness Ra of the pressure roller (JIS)
B0601) is preferably 3 μm or less.

Elastic layer 24b used for pressure roller 24
Is not particularly limited as long as the pressure-contact nip portion N having a desired width can be formed, but is preferably 2 to 6 mm.

In the present invention, the elastic layer 24b is a rubber composition including the resin microballoons 24c in the elastic layer 24b, as long as the thermal conductivity is 0.146 W / m · K or less. Is not particularly limited. Since the resin microballoon 24c has a substantially spherical shape with an average particle size of about 100 μm and contains air having excellent heat insulating properties inside, the microballoon is contained as a filler in the elastic layer 24b, so that the elastic layer The thermal conductivity of 24b can be reduced.

By including such a filler in the elastic layer, the thermal conductivity of the elastic layer 24b can be reduced without using a foamed material as the elastic layer.
For this reason, the elastic layer 24b can have a low surface roughness, and the pressure roller 24 can be configured such that the surface of the release layer 24b does not have irregularities even in the press-contact nip portion N.

The above effect is given to the pressure roller 24 and
When filling silicone rubber with microballoons,
Considering the shape, the average diameter of the microballoons is 80-
300 μm is preferable, and the stability of thermal conductivity
Is more preferably 80 to 200 μm. Ma
The microballoon has a true density of 400 kg / m.
^ThreeThe following is preferred, work on silicone rubber
20-60 kg / m^ThreeMore to be
preferable.

Preferred examples of the shell of the microballoon 24c include a vinylidene chloride resin and an acrylonitrile resin as thermoplastics and a phenol resin as a thermosetting resin. The microballoons made of each of the above materials may be used alone or as a mixture of two or more.

As the base material for containing the microballoons in the elastic layer 24b, those known as the elastic layer of the conventional pressure roller can be used, but silicone rubber and fluorine rubber are preferably used. it can.

When the thermal conductivity of the elastic layer 24b is within the above range, the elastic layer 24b of the resin microballoon 24c is formed.
Although the content in the elastic layer 24 is not particularly limited, for example, when the content of the resin microballoon 24c is changed,
The thermal conductivity of b can be measured, and the content at which the preferred thermal conductivity is obtained can be selected as the preferred content of the microballoon.

The elastic layer 24b containing the microballoons 24c may be one in which microballoons are contained in a rubber layer such as silicone rubber. In addition, a layer formed by including a microballoon in such a rubber layer on a layer formed of a foam may be used as the elastic layer 24b in the present invention.

The release layer 24d is formed of the elastic layer 24b
The elastic layer 24b may be formed by coating a PFA tube on the elastic layer 24b, or by coating the elastic layer 24b with a fluoro rubber or a fluoro resin such as PTFE, PFA, and FEP. The thickness of the release layer 24d is not particularly limited as long as the release roller 24d can provide a sufficient release property to the pressure roller 24.
0 μm.

The elastic layer of the pressure roller manufactured in this manner has a void formed by rubber and resin microballoons, and a resin shell of the resin microballoon exists between the rubber and the void. ing. During use as a pressure roller of the heat fixing device, when the resin shell is broken due to the heat history, the hardness of the pressure roller changes, and as a result, the fixing nip width changes, and the heat fixing performance changes. . for that reason,
It is also effective to use a resin microballoon which does not break even if the shell of the resin receives a heat history. A thermosetting resin microballoon is effective as such a microballoon.

For example, the heat resistance temperature of a microballoon made of acrylonitrile resin is about 200 ° C., and if the temperature of the pressure roller 24 rises above this, there arises a problem that the hardness of the pressure roller 24 decreases. Further, when the small-sized transfer material P is continuously passed through the heat fixing device 6, the recording material P on the surface of the pressure roller 24 in the pressure nip N is formed.
Is not taken away by the transfer material P, so that a small-size transfer material P is not taken away.
, The temperature of the non-sheet passing area rises to about 200 ° C. Therefore, in the pressure roller 24 according to the first embodiment, the number of small-sized transfer materials P (throughput) that passes through the pressure contact nip N per unit time is significantly reduced, assuming a temperature rise on the roller surface. And so on.

On the other hand, a micro balloon having an outer shell made of a thermosetting phenol resin is used. Since the heat resistance temperature of the microballoon whose outer shell is a phenol resin is 300 ° C., when the small-size paper described above is continuously passed as the transfer material P, the heat resistance temperature in the non-paper passing area is set to the silicone rubber. 230 ℃ ～ 24 which is heat resistant temperature
It can be set to 0 ° C. Therefore, it is possible to set a large throughput in which a response assuming a temperature rise in the non-sheet passing area is simplified. Therefore, the heat fixing speed per unit time can be increased.

It is also effective to use thermoplastic resin microballoons and thermosetting resin microballoons in order to set the hardness and heat-resistant temperature of the pressure roller within predetermined ranges.

For example, a microballoon whose outer shell is made of acrylonitrile resin may have an excessively low roller hardness at about 200 ° C. when filled in an amount of 1 wt% or more with respect to the elastic layer 24b. Roller 2
Even if the temperature of No. 4 becomes 200 ° C. or more, there is no influence of hardness.
Therefore, it is desirable that the content of the microballoons whose outer shell is made of acrylonitrile be 1 wt% or less in consideration of the temperature rise in the non-sheet passing area when small size paper is continuously passed as the transfer material P.

The hardness of the pressure roller 24 is preferably 55 ° or less (load of 600 g of Asker C hardness meter), more preferably 50 ° or less. In order to keep the hardness of the pressure roller 24 in this range, it is preferable that the filling amount of the microballoon whose outer shell is phenol is set to 20 wt% or less.

Further, if the resin microballoons contained in the elastic layer of the pressure roller are broken by the heat history in the process of being used as a heat fixing device, the hardness of the pressure roller is reduced. It is also effective to break the resin shell of the resin microballoon contained in the elastic layer in advance and leave the broken resin shell between the rubber and the gap.

The manufacture of such a pressure roller will be described below.

The unexpanded resin microballoon to be used is a powder in which a volatile substance using a thermoplastic resin is included in the outer shell, and expands by heat. Examples of the thermoplastic resin include vinylidene chloride / acrylonitrile copolymer, methyl methacrylate / acrylonitrile copolymer, and methacrylonitrile / acrylonitrile copolymer. Examples of the volatile substance included therein include hydrocarbon isobutane such as butane and isobutane. ing.

As the resin used as the outer shell, a resin having a softening temperature within an appropriate range in accordance with the curing temperature of the liquid silicone rubber material is selected.

These unexpanded resin microballoons can be easily obtained from the market as "Matsumoto Microfair F" series by Matsumoto Yushi Seiyaku Co., Ltd. and "Expancel" series by Expancel. Unexpanded resin microcapsules obtained from these markets usually have a diameter of about 1 to 50 μm, and are expanded at an appropriate heating temperature to become spheres having a diameter of about 10 to 500 μm, which are almost true spheres. .

Examples of the silicone oil used to prevent the resin microballoons from scattering include various modified silicone oils such as dimethylpolysiloxane and methylhydrogenpolysiloxane, amino-modified silicone, epoxy-modified silicone and carbinol-modified silicone. Add an equivalent amount or less of silicone oil to unexpanded resin microballoons, or leave or stir,
The method of wetting is not particularly limited. The added silicone oil is preferably 50 to 100 parts by weight based on 100 parts by weight of the unexpanded resin microballoon. When the amount is less than 50 parts by weight, a sufficient scattering prevention effect cannot be obtained. When the amount exceeds 100 parts by weight, a problem may occur in inflation of the microballoon.

Subsequently, the resin microballoon which has been heated and expanded to the predetermined size is cooled, and then mixed / kneaded and dispersed in a liquid silicone rubber material. In addition, when mixing or kneading, it is preferable to mix at or below the softening point of the resin constituting the inflated resin microballoon in order to prevent the inflated resin microballoon from being broken by heat.

The liquid silicone rubber material may be any material as long as it is liquid at room temperature and is cured by heat to form a silicone rubber having rubber-like elasticity. Such a liquid silicone rubber material is composed of an alkenyl group-containing diorganopolysiloxane, a silicon-bonded hydrogen atom-containing organohydrogenpolysiloxane, and a reinforcing filler, and is cured by an platinum-based catalyst to form a silicone rubber. Liquid silicone rubber composition, an organic peroxide-curable silicone rubber composition comprising an alkenyl group-containing diorganopolysiloxane and a reinforcing filler, cured with an organic peroxide to form a silicone rubber, a hydroxyl group-containing diorgano Consisting of polysiloxane and organohydrogenpolysiloxane containing silicon-bonded hydrogen atoms and a reinforcing filler, an organotin compound,
A condensation reaction-curable liquid silicone rubber composition which is cured by a condensation reaction-promoting catalyst such as an organotitanium compound or a platinum-based catalyst to form a silicone rubber is exemplified. Among these,
An addition reaction-curable liquid silicone rubber material is preferred because of its high curing speed and excellent curing uniformity.

In order for the cured product to become a rubber-like elastic material, it is preferable that the viscosity at 25 ° C. containing a linear diorganopolysiloxane as a main component is 100 centipoise or more.

The liquid silicone rubber material may contain various fillers, if necessary, pigments for adjusting the fluidity and improving the mechanical strength of the cured product within a range not to impair the object of the present invention. A compound containing a heat-resistant agent, a flame retardant, a plasticizer, an adhesion-imparting agent, or the like may be used.

The blending amount of the inflated microballoon is selected according to the desired heat insulating property. Liquid silicone rubber material 100
The amount is preferably 1 to 10 parts by weight based on parts by weight. If the amount is less than 1 part by weight, sufficient heat insulation required for the pressure roller cannot be obtained,
If the amount exceeds 10 parts by weight, the viscosity of the liquid silicone rubber material increases and mixing and stirring becomes difficult.

Next, the silicone rubber material is heat-cured on a cored bar at a temperature not higher than the heat expansion temperature. The means and method of forming the roller by heat curing is not limited, but the roller is formed by mounting a metal core in a pipe-shaped mold having a predetermined inner diameter, injecting the silicone rubber material and heating the mold. This method is simple and suitable. At this time, if the heating temperature is equal to or higher than the softening point of the resin microballoon, the balloon may be thermally deformed and a uniform sponge may not be formed.

More preferably, after the cured silicone rubber roller is released from the mold, the silicone rubber roller is heated at a temperature equal to or higher than the heat expansion temperature. Here, the resin balloon undergoes heat shrinkage and breaks, leaving voids in the trace, and a uniform sponge form is maintained. Therefore, the sponge form of the silicone rubber roller can be used in a stable state without being affected by the thermal degradation of the resin due to the heat history during actual use.

In order to obtain good heat insulating properties and strength, it is preferable that the resin balloon expanded by heating has an average particle size of 80 to 200 μm.

The average particle diameter means an average value of (diameter + minor axis) / 2 of ten balloons randomly selected in the visual field by microscopic observation.

If the inflated resin balloon has a particle diameter in this range, the heat insulating property required for the heat insulating pressure roller can be obtained with a small amount of compounding, and the mixing and stirring with the silicone rubber material is easy.

When the average particle size of the heat-expanded resin balloon is 80 μm or less, a large amount of compounding may be required to obtain the heat insulation required for the heat insulating pressure roller.
When a layer having a thickness of more than μm is used, a problem may occur in the mechanical strength of the elastic layer.

As the silicone oil, methyl hydrogen polysiloxane is preferred from the viewpoint of the heat resistance of a silicone rubber sponge.

The case where the silicone oil is an amino-modified silicone oil is also preferable in view of the heat resistance of the silicone rubber sponge.

FIG. 3 is a schematic sectional view showing the structure of another pressure roller. An elastic layer 100 of the pressure roller 24 includes a foamed elastic layer 101 and an elastic layer 24b formed on the outer peripheral surface of the foamed elastic layer 101 and having a shell and including a microballoon 24c, Other parts are the same as those in FIG.

FIGS. 4A to 4D show other examples of the configuration of the film heating type heating device (heating fixing device).

FIG. 4A shows an endless belt between three substantially parallel members of a heating body 22 held by a heating body holder / film guide member 25, a film driving roller 26, and a tension roller 27. A heat-resistant film 23 is stretched and stretched, and the heating element 22 is sandwiched between the films 23.
The pressure roller 24 is pressed against the pressure roller 24 to form a pressure contact nip N, and the film 23 is driven to rotate by the drive roller 26. The pressure roller 24 rotates following the rotation of the film 23. Reference numeral 27 denotes a drive source of the film drive roller 26. Transfer material P as a material to be heated in press nip N
To fix the toner image by heating.

FIG. 4 (b) shows an endless belt-like heat resistance between a heating element 22 held by a heating element holder / film guide member 25 and a film driving roller 26. The film 23 is stretched and suspended, and the heating body 22 and the pressure roller 24 are pressed against each other with the film 23 interposed therebetween to form a pressure contact nip portion N. The film 23 is driven to rotate by the drive roller 26. The pressure roller 24 rotates following the rotation of the film 23.

FIG. 4C shows the heat-resistant film 23.
Using a long end film rolled as a roll, this is fed from the feeding shaft 28 through the lower surface of the heating element 22 held by the heating element holder and film guide member 25,
The heating member 22 and the pressure roller 24 are pressed against each other with the film 23 interposed therebetween, and the pressure contact nip N
Is formed, and the film 23 is wound up by the winding shaft 29 and travels at a predetermined speed. In the apparatus having the above-described configuration, the same effect as described above can be obtained by using the pressure roller 24 as the pressure means according to the present invention.

The heating element 22 on the side of the heating means is not limited to the above-described ceramic heater, and other appropriate heating elements such as an electromagnetic (magnetic) induction heating method can be adopted. (D) is an example of the electromagnetic induction heating method. Numeral 30 denotes a magnetic metal member which generates heat by electromagnetic induction, and 31 denotes an exciting coil as a magnetic field generating means. The magnetic metal member 30 generates electromagnetic induction heat as a heater by a high-frequency magnetic field generated by energizing the excitation coil 31, and the heat is applied to the film 2 at the press-contact nip N.
The transfer material P is applied to the transfer material P as the material to be heated, which is introduced into the press-contact nip portion N, through the transfer member 3. The film 23 itself may be a member having electromagnetic induction heat generation.

FIGS. 5A and 5B show examples of the configuration of a heating device (heat fixing device) of a heat roller type.

In FIG. 5A, reference numeral 32 denotes a heating roller (fixing roller) as a heating means, which is a hollow metal roller made of iron or aluminum having a release layer made of a fluororesin or the like on its outer peripheral surface. Halogen heater 33 as heat source
Is built in. The heating roller 32 and the pressure roller 2
4 is press-contacted to form a press-contact nip portion. A transfer material P as a material to be heated is introduced into the pressure nip N to heat and fix the toner image.

In FIG. 5B, the heating roller 32 is heated by an electromagnetic induction heating method. Heating roller 3
2 is made of a ferromagnetic material. In heating, a high-frequency AC current is applied to an exciting coil 35 wound around an exciting core 34 to generate a magnetic field, and an eddy current is generated in the heating roller 32. That is, an eddy current is generated in the heating roller by the magnetic flux, and the heating roller 32 itself generates heat by Joule heat.
Reference numeral 36 denotes an auxiliary core disposed to face the excitation core 34 with a heating roller therebetween to form a closed magnetic path.

In the heating device of the heat roller type as described above, the same operation and effect as described above can be obtained by using the pressure roller 24 as the pressure means according to the present invention.

In short, the present invention is effective for a heating apparatus in which a material to be heated is introduced into a press-contact nip portion between a heating means and a pressurizing means, nipped and conveyed, and heat-treated. Not only as a device, but also, for example, a device for improving the surface properties (such as gloss) by heating a recording material carrying an image, a device for temporarily attaching, a device for feeding and drying a sheet-like material, Of course, it can be widely used as a heating device such as a device for laminating.

[0102]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

<Example 1> An aluminum material having a diameter of 13 was used for the core 24a, and an elastic layer 24b was formed outside the core 24a.
Was formed as follows.

As the resin microballoon 24c, an inflated microballoon (trade name: F80-ZD, Matsumoto Yushi Pharmaceutical Co., Ltd.) having an average particle size of about 100 μm, a shell material of acrylonitrile resin, and a true density of about 35 kg / cm ^3. 3 parts (weight) of addition type liquid silicone rubber (viscosity 130 Pa)
・ S, specific gravity 1.17, trade name: DY35-561A /
B, 97 parts by Dow Corning Toray Co., Ltd.) and heat-cured at 130 ° C. in a mold.

As a result, 3 wt.
% Silicone rubber elastic layer 24b containing 3% dispersion
was gotten. The thermal conductivity of the elastic layer 24b is 0.0
It was 963 W / m · K. The surface roughness is R
a1 μm.

Next, a release layer 24d having a thickness of 30 μm was formed on the outer periphery of the elastic layer 24b as follows.

A fluoro rubber latex (trade name: GLS213, manufactured by Daikin Industries, Ltd.) is applied on the elastic layer 24b, and near infrared rays are radiated from the outside, and the surface temperature is 290 ° C.
For 15 minutes. In this firing step, the elastic layer itself is not heated much due to the irradiation of near infrared rays from the outside, and the resin shell of the resin microballoon is not broken. The roller surface roughness after forming the release layer 24d as the outermost layer was Ra 1.5 μm. This elastic roller was used as the pressure roller 24 of the above-described film heating type heat fixing device 6 shown in FIG. Roller hardness is about 45 ° (ASK
ER-C hardness tester, load 600 g).

The film 23 is made of a 50 μm-thick polyimide seamless tube and a 10 μm-thick PTF.
The one on which the E layer was formed was used.

The total pressure of the entire nip is 10 k
g of pressure. The nip width at this time was about 6 mm.

A power of 450 W is supplied to the heating element 22.
The process speed is set to 72 mm / sec,
From the room temperature until the heater temperature regulation temperature reaches 190 ° C., and the fixability when the transfer material P is passed after 5 seconds,
The toner stain on the pressure roller when halftone paper was continuously fed for 100 sheets was evaluated.

The fixing property was determined by LA LBP manufactured by Canon Inc.
A 5 mm square solid black is printed as an unfixed image on a Fox River 24 lb paper as an unfixed image by SER SHOT LBP-350, and after passing through the heat fixing device 6 under the above conditions, the solid black image is formed with a nonwoven fabric at 10 g / cm. The density before and after rubbing with pressure ² is a Macbeth reflection density type of reflection type (RD914: DIVISION OF KOLL).
MORGEN INSTRUMENT CO. ) Was evaluated. Table 1 shows the evaluation results. In addition, in the fixing property and the roller contamination in Table 1, each symbol indicates the following evaluation. (Fixability) ○: good ×: bad (roller stain) ：: not stained ×: stained <Comparative Example 1> In Example 1, a layer made of solid silicone rubber (trade name: DY35-561A / B) as an elastic layer And using a fluoro rubber latex layer (trade name: GLS213) having a thickness of 30 μm as a release layer, using the same method as in Example 1 to increase the rise time of the heat fixing device and the transfer material P. Of image fixation and roller 2
Stain 4 was evaluated for staining. Table 1 shows the evaluation results.

<Comparative Example 2> In Example 1, a liquid silicone rubber (trade name: DY35-560A) was used as the elastic layer.
/ B, a layer made of a foamed elastic material formed by foaming Dow Corning Toray Co., Ltd.), and a 30 μm-thick PFA tube (manufactured by DuPont, trade name:
The rise time of the heat fixing device, the fixability of the image to the transfer material P, and the contamination of the roller 24 with the toner were evaluated using the same method as that of Example 1 except that the layer made of 450 HPJ) was used. Table 1 shows the evaluation results.

<Comparative Example 3> In Example 1, solid silicone rubber (trade name: DY35-56) was used as the elastic layer.
0A / B) 97 parts of hollow silica (trade name: CELSTAR S)
X39, manufactured by Tokai Kogyo Co., Ltd.), the same as Example 1, except that a fluoro rubber latex layer (trade name: GLS213) having a thickness of 30 μm was used as a release layer. And the fixing time of the image to the transfer material P,
Stain 4 was evaluated for staining. Table 1 shows the evaluation results.

[0114]

[Table 1]

From the above results, by filling the microballoons 24c in the elastic layer 24b, the rise of the fixing heater 22 becomes faster than that of the comparative example 1, and even when the transfer paper comes to the fixing nip in a short time, good results can be obtained. It turns out that fixability is obtained.

This is because the microballoon 24c contains air having excellent heat insulating properties inside, so that the thermal conductivity is reduced and the amount of heat taken by the pressure roller when the heater is started is reduced. This is probably because the time required for the fixing state is reduced.

Further, as compared with Comparative Example 2, although the fixing ability is the same, the roller of this embodiment is much better with respect to roller contamination.

This is because, in Comparative Example 2, the PFA tube becomes the foam cell diameter when pressurized, so that the unevenness occurs in the nip and the toner enters into the concave and the dirt accumulates. In the roller of the embodiment, since the surface roughness of the elastic layer is close to the mirror surface state, there is no unevenness in the roller surface layer at the nip portion even during pressurization, and the roller is not stained with toner even when paper is passed. is there.

In Comparative Example 3, the thermal conductivity can be set low. For that purpose, it is necessary to fill a large amount of 50 parts of hollow silica into silicone rubber. , Resulting in a roller hardness of 60 °
That is all. For this reason, the fixing nip cannot be widened, and a sufficient amount of heat for fixing can be supplied to the transfer material P even if the rise is early, and good results cannot be obtained in both the fixing property and the roller contamination.

Example 2 A pressure roller was manufactured in the same manner as in Example 1 except that the elastic layer 24b was formed as follows.

The resin microballoon 24c has an average particle size of about 90 μm, a shell material of phenol resin, and a true density of about 2 μm.
30 kg / m ³ pre-inflated micro balloon (trade name:
20 parts (by weight) of BJO-0930, manufactured by Asia Pacific Microsphere Co., Ltd. are mixed with 100 parts of an addition-type liquid silicone rubber (trade name: DY35-561A / B), and heat-cured at 130 ° C. in a mold. Was.

As a result, the resin microballoon was used for 16.
A 3 mm-thick silicone rubber elastic layer 24b containing 6% by weight of dispersion was obtained. The thermal conductivity of the elastic layer 24b is
It was 0.125 W / m · K. The surface roughness was Ra 1 μm.

When the thus manufactured pressure roller was evaluated in the same manner as in Example 1, good results were also obtained with respect to the fixing property and the roller contamination. The time required for the heater temperature to reach 190 ° C. was 5 seconds.

In the case of the pressure roller of Example 1, in the fixing evaluation, when 15 sheets of small-size envelopes (COM10) are continuously passed as the transfer material P, the non-sheet-passing area of the pressure roller Became 200 ° C. The heat resistant temperature of the resin microballoon in the elastic layer of the pressure roller is 20
Since the temperature is around 0 ° C., the throughput must be reduced to half the speed after 16 sheets so as to increase the interval between the sheets so that the non-sheet passing area does not exceed 200 ° C. On the other hand, when the pressure roller according to the present embodiment is used, the non-sheet passing area only rises to 220 ° C. even after 50 sheets have passed, and the resin of the pressure roller according to the present embodiment also Since the heat resistance temperature of the microballoon is about 250 ° C., in order to maintain 220 ° C. after 50 sheets, the throughput speed is increased by 2/3 by increasing the paper interval.
And

Example 3 A silicone rubber having a hardness of 5 ° when a test piece having a thickness of 12 mm was measured by a JIS-A hardness tester (1 kg load) (trade name: DY35-561)
In A / B), microballoons whose outer shell is made of acrylonitrile resin (Matsumoto Yushi Pharmaceutical Co., Ltd. F80-ZD)
And a microballoon whose outer shell is made of a phenolic resin (BJO-09 from Asia Pacific Microhear)
30) to form an elastic layer 24b. The content of each microballoon in each elastic layer was changed as shown in Table 2. Each of the elastic layers 24b was applied to the apparatus of Example 1, and the hardness of the pressure roller 24 and the heat resistance temperature at which the roller hardness could be maintained were measured. Table 2 shows the evaluation results.

[0126]

[Table 2]

From the above results, the temperature at which the hardness of the microballoon of which the outer shell is acrylonitrile decreases to 200 ° C. when filled at 1 wt% or more is 200 ° C., but there is no effect when the filled amount is smaller. Therefore, it is desirable that the outer diameter of the microballoon made of acrylonitrile be 1 wt% or less in consideration of the temperature rise in the non-sheet passing portion when small size paper is continuously passed. In addition, the filling amount of the microballoon whose outer shell is phenol is 55 ° as the roller hardness.
(Asker C hardness meter load of 600 g) or less, and preferably 50 ° or less, if possible, it is desirable that the filling amount is 20 wt% or less as described above.

As for the roller hardness, the hardness of the base rubber or the thickness of the elastic layer may be finely adjusted after adjusting the thermal conductivity by the compounding ratio in order to obtain a desired hardness.

As described above, by dispersing two types of microballoons in silicone rubber, excellent heat resistance is achieved,
In addition, the elastic body has low heat conduction and can adjust the roller hardness.

<Example 4> Unexpanded resin microballoon (trade name: Matsumoto Microsphere F85: particle diameter 20 to 30 µm, true specific gravity 1.04, softening point 150)
100 parts by weight of dimethyl silicone oil (trade name: dimethylpolysiloxane: KF96 100CS; Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by weight of 155 ° C .; A paste-like mixture was obtained. This paste-like mixture was left to dry in a 90 ° C. oven for 1 hour. After cooling, the resin was allowed to stand in an oven set at a heat expansion temperature of 150 ° C. for 30 minutes to obtain expanded resin microballoons having an average particle diameter of 108 μm. Addition type liquid silicone rubber material (viscosity 130 Pa · s, specific gravity 1.17, trade name:
DY35-561A / B: Dow Corning Toray) 1
8 parts of the expanded resin microballoon (corresponding to 4 parts of the microballoon itself) is added to 00 parts by weight, and a universal mixing stirrer (trade name: Dalton: Sanei Manufacturing Co., Ltd.) is added at room temperature.
For 10 minutes to obtain a liquid silicone rubber material mixture. The volume of the resin microballoon was increased about 60 times in bulk volume, but there was no trouble due to scattering at the time of the next measurement and blending step. This is due to the adhesive force of dimethyl silicone oil on the surface of the inflatable resin microballoon. next,
After injecting the liquid silicone rubber material mixture into a pipe-shaped mold in which an aluminum cored bar 24a having been subjected to a primer treatment is disposed, the mixture is heated and cured using a hot plate set at 130 ° C., and then removed from the mold. By heating for 2 hours in an oven set at ° C., the resin microballoon shell of the resin microballoon was broken to form a roller having a silicone rubber elastic layer 24b. The thermal conductivity of this elastic layer is 0.085 W / m · K.

After the surface of the silicone rubber elastic roller is subjected to a predetermined primer treatment (trade name: GLP103SR: manufactured by Daikin Industries, Ltd.), a fluoro rubber latex (trade name: GLS213, manufactured by Daikin Industries, Ltd.) is used as the release layer 24d. )) Is spray-coated with a thickness of about 30 μm,
After drying at 70 ° C, 30 minutes in an oven set at 310 ° C.
The silicone rubber pressure roller having a rubber length of 225 mm, a rubber thickness of 2.5 mm, and an outer shape of 20 mm was obtained.

Example 5 Unexpanded resin microballoons (Matsumoto Microsphere F85: particle diameter 20-30 μm, true specific gravity 1.04, softening point 150-155 ° C.) used in Example 4; Matsumoto Yushi Pharmaceutical Co., Ltd.) was directly dried in an oven at 90 ° C. for 1 hour without moistening the silicone oil.
It was left in an oven set at 30 ° C. for 30 minutes to obtain expanded resin microballoons having an average particle size of 110 μm.
100 parts by weight of an addition-type liquid silicone rubber material (viscosity: 130 Pa · s, specific gravity: 1.17, DY35-561A / B: Dow Corning Toray Co., Ltd.), 4 parts of the expanded resin microballoons are blended, and a universal mixing stirrer is used at room temperature. (Dalton:
The mixture was mixed and stirred at Sanei Seisakusho for 10 minutes to obtain a liquid silicone rubber material mixture. The volume of the resin microballoon was increased about 60 times, and the workability was poor due to scattering at the time of measurement and blending. Next, a 30 μm-thick PFA tube with an inner surface subjected to a primer treatment was arranged inside the pipe-shaped mold, and an aluminum cored bar with a primer treatment was arranged at the center of the pipe-shaped mold. After injecting the liquid silicone rubber material mixture between the PFA tube and the aluminum core,
Heat-cured using a hot plate set at 30 ° C, rubber length 2
A silicone rubber pressure roller having a thickness of 25 mm, a rubber thickness of 2.5 mm, and an outer shape of 20 mm was used. The thermal conductivity of the silicone rubber elastic layer is 0.085 W / m · K.

<Example 6> Unexpanded resin microballoon (Matsumoto Microsphere F85: particle size of 20 to
30 μm, true specific gravity 1.04, softening point 150-155
° C; Matsumoto Yushi Pharmaceutical Co., Ltd.) 100 parts by weight of silicone oil (methyl hydrogen polysiloxane: KF9)
9; Shin-Etsu Chemical Co., Ltd.) 50% toluene solution 10
After adding 0 parts by weight and stirring, the mixture was allowed to stand for 10 hours to obtain a mixture moistened with silicone oil. 90 ° C.
It was left to dry in the oven for 1 hour. After cooling, the resin was allowed to stand in an oven set at a heat expansion temperature of 150 ° C. for 30 minutes to obtain expanded resin microballoons having an average particle diameter of 108 μm. Addition type liquid silicone rubber material (viscosity 40Pa)
S, specific gravity 1.02, DY35-446A / B: Toray
Dow Corning Co.) 3 parts of the expanded resin microballoon (100 parts by weight) (equivalent to 2 parts of the microballoon itself)
The mixture was mixed and stirred at room temperature for 10 minutes with a universal mixing stirrer (Dalton: Sanei Seisakusho) to obtain a liquid silicone rubber material mixture. Thereafter, a silicone rubber pressure roller having a rubber length of 225 mm, a rubber thickness of 2.5 mm, and an outer diameter of 20 mm was obtained in the same manner as in <Example 4>. The thermal conductivity of the silicone rubber elastic layer is 0.094 W / m · K.

<Example 7> Unexpanded resin microballoon (Matsumoto Microsphere F85: particle diameter of 20 to
30 μm, true specific gravity 1.04, softening point 150-155
° C; Matsumoto Yushi Seiyaku Co., Ltd.) 100 parts by weight of silicone oil (amino-modified silicone: SF8417; Toray
100 parts by weight of Dow Corning Co., Ltd.) was added, stirred, and allowed to stand for 10 hours to obtain a mixture wet with silicone oil. This paste-like mixture was left to dry in a 90 ° C. oven for 1 hour. After cooling, the resin was allowed to stand in an oven set at a heat expansion temperature of 150 ° C. for 30 minutes to obtain expanded resin microballoons having an average particle diameter of 102 μm. Addition type liquid silicone rubber material (viscosity 40 Pa · s, specific gravity 1.02, DY35
-446A / B: 100 parts by weight of Dow Corning Toray), 4 parts by weight of the expanded resin microballoon (corresponding to 2 parts of the microballoon itself) and a peroxide vulcanizing agent (R
C-2: 2,4-dichlorobenzoyl peroxide,
1 part by weight of Dow Corning Toray Co., Ltd.) was mixed and stirred at room temperature for 10 minutes with a universal mixing stirrer (Dalton: Sanei Seisakusho) to obtain a liquid silicone rubber material mixture. Hereinafter, in the same manner as in <Example 4,> a silicone rubber heat insulating pressure roller having a rubber length of 225 mm, a rubber thickness of 2.5 mm, and an outer shape of 20 mm was obtained. The thermal conductivity of the silicone rubber elastic layer is 0.
It is 105 W / m · K.

<Experimental Example> Next, an experimental example conducted to confirm the performance of the pressure rollers of Examples 4 to 7 will be described.

FIG. 2 is a schematic cross-sectional view of a film heating type fixing device used in this experimental example.

The heat-resistant film 23 is made of a seamless polyimide film having a thickness of 40 μm and an outer diameter of 25 mm, and a fluororesin dispersion (a mixture of PTFE and PFA mixed at 50/50) as a release layer via a fluorine-based primer having a thickness of 5 μm. Coating, firing and cutting to a length of 230 mm were used.

Reference numeral 24 denotes a pressure roller.
7) were sequentially subjected to experiments.

A paper passing test was performed using the above-mentioned film heating type fixing device under the following conditions. First, 100 sheets of unfixed image formed by a laser beam printer (trade name: Laser Shot LBP350, manufactured by Canon Inc.) are printed at a constant interval of 8 sheets / min.
Zero sheets were continuously passed, and immediately after that, five sheets of A4 size paper in the longitudinal direction were passed, and the transportability at that time was evaluated. The results are shown in Table 3.

[Test conditions] Pressure roller peripheral speed: 50 m
m / sec ・ Nip pressure: 9 kgf ・ Maximum supply power: 500 W ・ Fixing set temperature: 190 ° C. In the fourth embodiment, the hardness (ASK-C) decreases at both the roller center and the end (A5 non-paper passing portion). The difference was small and there was no problem in transportability of paper wrinkles and the like through A4 size paper.

On the other hand, in the fifth embodiment, the hardness of the roller end portion (A5 non-sheet passing portion) is greatly reduced, and the difference in hardness between the center portion and the end portion of the roller is large.
A problem occurred in transportability.

In Examples 6 and 7, the decrease in hardness (ASK-C) was small at both the center and the end of the roller (the A5 non-sheet passing portion), and there was no problem in transportability of paper wrinkles and the like through A4 size paper. .

[0143]

[Table 3]

[0144]

As described above, the heating device according to the first aspect of the present invention is provided with the pressure roller having a low thermal conductivity and a small hardness, so that the heat from the heating means can be efficiently used. You can do it.

In the second method for producing a silicone rubber sponge of the present invention, the scattering of resin microballoons in the production process can be prevented by silicone oil.

Further, in the method of manufacturing a silicone rubber roller according to the third aspect of the present invention, when used as a pressure roller of a heat fixing device, the hardness and thermal conductivity do not change even when subjected to heat history, and the fixing performance is not changed. It is possible to manufacture a roller that does not deteriorate.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.

FIG. 2 is a schematic configuration diagram of the heat fixing device of FIG. 1;

FIG. 3 is a configuration diagram of a pressure roller containing a resin microballoon.

FIGS. 4A to 4D are schematic diagrams each showing a configuration example of a heat fixing device of a film heating type.

FIGS. 5A and 5B are schematic diagrams each showing a configuration example of heat fixing by a heat roller method.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 83/04 C08L 83/04 4J002 H05B 3/00 335 H05B 3/00 335 6/14 6/14 (72 Inventor Yusuke Nakazono, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Satoru Taniguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nagata Hikari 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kazuo Kishino 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaaki Takahashi Ota, Tokyo 3-30-2 Shimomaruko-ku, Canon Inc. (72) Inventor Hideo Kawamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Meiji Osamu Osamu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yuji Kitano 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo F-term (reference) 2H033 AA09 AA16 AA20 AA25 AA30 BA05 BB05 BB15 BB29 BB30 BB31 BB33 3J103 AA02 AA15 AA51 BA02 FA01 FA15 FA30 GA02 GA52 GA57 GA58 HA03 HA12 HA18 HA41 HA53 3K058 AA87 BA18 CA61 DA02 DA04 DA26 GA06 3K0AAAAADAADA AF02 BA37 BA38 CB62 CB73 CB76 CB78 CB79 CB84 CC04X CC04Y CC22X CC30X CC32Y CC32Z CC42 CE02 CE50 CE98 DA03 DA07 DA09 DA15 DA20 DA24 DA54 DA59 4J002 CP041 CP061 CP141 EA016 FA106 FB096 FD010 FD140 FD150 GM

Claims (29)

[Claims] 1. A heating means for heating a sheet-shaped material to be heated, and a pressure roller disposed opposite to the heating means and pressed against the heating means, wherein the heating means and the pressure roller In a heating device that heats the material to be heated by introducing the material to be heated into the pressure contact nip portion and nipping and transporting the material, the pressure roller has an elastic layer dispersedly containing a void formed by the resin microballoon. A heating device, characterized in that: 2. The thermal conductivity of the elastic layer is 0.146 W / m ·
The heating device according to claim 1, wherein the temperature is equal to or lower than K. 3. The heating device according to claim 1, wherein the elastic layer is a rubber layer containing voids dispersed therein. 4. The heating device according to claim 3, further comprising a resin shell forming a resin microballoon between the rubber and the gap. 5. The heating device according to claim 3, wherein the resin microballoon is present between the rubber and the gap in a state where the shell of the resin is broken. 6. The heating device according to claim 1, wherein the resin forming the shell of the resin microballoon is a thermoplastic resin. 7. The heating device according to claim 6, wherein the thermoplastic resin is a thermoplastic resin selected from the group consisting of an acrylonitrile resin and a vinylidene chloride resin. 8. The heating device according to claim 1, wherein the resin forming the shell of the resin microballoon is a thermosetting resin. 9. The heating device according to claim 8, wherein the thermosetting resin is a phenol resin. 10. The heating device according to claim 1, wherein the resin microballoon is a mixture of a microballoon whose shell is a thermoplastic resin and a microballoon whose shell is a thermosetting resin. 11. The resin microballoon having an average particle size of 8
The heating device according to claim 1, wherein the thickness is 0 to 200 μm. 12. The heating device according to claim 1, further comprising a release layer as an outermost layer of the pressure roller. 13. The heating device according to claim 12, wherein the release layer is formed of a material selected from the group consisting of a fluororesin and a fluororubber. 14. The pressure roller has a surface roughness (Ra) of 3 μm.
2. The roller heating device according to claim 1, wherein m is equal to or less than m. 15. The pressure roller has a surface hardness of Asker C.
The heating device according to claim 1, wherein the heating device is at most 55 °. 16. The heating device according to claim 1, wherein the pressure roller has a foamed elastic layer as an inner layer of the elastic layer. 17. The recording medium according to claim 1, wherein the unfixed image is a recording material carrying an unfixed image, and the unfixed image is heated and fixed at a pressure nip portion between an overheating means and a pressure roller. The heating device according to claim 1. 18. An image forming apparatus comprising: an image forming means for forming and supporting an unfixed image on a recording material; and a heat fixing device for heating and fixing the unfixed image to the recording material. An image forming apparatus, comprising: the heating device according to claim 1. 19. A method of heating and expanding an unexpanded resin microballoon wet-treated with silicone oil, a step of mixing the heat-expanded resin microballoon with a liquid silicone rubber material, and a step of heat-curing the liquid silicone rubber. A method for producing a silicone rubber sponge. 20. The method according to claim 19, further comprising the step of heating the liquid silicone rubber to a temperature higher than the expansion start temperature of the resin microballoons to break the resin microballoon shape. Method for producing silicone rubber sponge. 21. The heat-expanded resin balloon having an average particle size of 80 to 200 μm.
10. A method for producing a silicone rubber sponge obtained by the production method according to 9. 22. The method according to claim 19, wherein the silicone oil is methyl hydrogen polysiloxane.
A method for producing the silicone rubber sponge according to the above. 23. The method for producing a silicone rubber sponge according to claim 19, wherein the silicone oil is an amino-modified silicone oil. 24. A roller having a silicone rubber sponge produced by the production method according to claim 19 on a cored bar. 25. A step of heat-expanding an unexpanded resin microballoon, a step of mixing the heat-expanded resin microballoon with a liquid silicone rubber material, and heating the mixture on a metal core to cure the liquid silicone rubber. And a step of heating the liquid silicone rubber after heat curing to break the microballoon shape of the resin microballoon outer shell resin by heating the resin microballoon to an expansion start temperature or higher. 26. The method according to claim 25, further comprising the step of forming a release layer on the surface after breaking the microballoon shape of the resin. 27. The method for manufacturing a roller according to claim 25, wherein the heat curing temperature of the liquid silicone rubber is lower than the expansion start temperature of the resin microballoon. 28. A pressure roller manufactured by the manufacturing method according to claim 25. 29. A heating means for heating a recording material carrying an unfixed image to fix the unfixed image, and a heating means disposed opposite to the heating means and pressed against the heating means to form a press-contact nip portion. 28. A heat fixing device having a pressure roller, wherein the pressure roller is a roller manufactured by the method for manufacturing a roller according to claim 25.