JP2002295452A - Roller furnished with elasticity and insulation property and heating device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roller furnished with elasticity and an insulation property free to adapt to a roller excellent in the insulation property, fast in rising due to heating and requiring the elasticity and a heating device using it. SOLUTION: The insulation property of an elastic body layer 47 is improved by carrying out vacuum-drawing to lower air density of the foam inside of foaming silicone rubber of the elastic body layer 47 and lowering heat conductivity of the foaming silicone rubber by using a fact that about 60% of heat discharged to the elastic body layer 47 is heat transmitted to an elastic body material, that is, the silicone rubber itself in this embodiment and remaining about 40% of it is heat transmitted through air in the foam in the elastic foaming body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller having elasticity and heat insulation which is suitably used in a heating apparatus in a dry electrophotographic apparatus, a drying apparatus in a wet electrophotographic apparatus and an ink jet printer, and an erasing apparatus for rewritable media. And a heating device using the same.

[0002]

2. Description of the Related Art It is desired that a fixing roller used in a fixing device, which is a kind of a heating device, has heat insulating property and elasticity from the viewpoint of thermal efficiency and so-called uniform nip pressure.

Conventionally, there has been a configuration in which a halogen lamp is disposed inside a fixing roller made of a hollow core metal such as aluminum and the halogen lamp generates heat to set the fixing roller at a predetermined temperature. Has a low heat conversion rate by a halogen lamp and is indirect heating by a halogen lamp, so that the efficiency of heat transfer from the halogen lamp to the hollow core metal of the fixing roller is low. Further, heat radiation to the air inside the hollow cored metal was inevitable.

Further, due to the problem of strength, there is a limit in reducing the thickness of the core of the fixing roller, and the heat capacity of the fixing roller is large.

[0005] As a result, there is a problem that the rise of the fixing roller at the start of heating is delayed, and the warm-up time is long.

In order to solve such a problem, Japanese Patent Laid-Open Publication No. Sho 59-46668 discloses a method in which a hollow wall is formed into a mirror surface, and a heat generating layer and a heat conductive layer are formed on the outer periphery of a vacuumed metal roller. A fixing roller in which an offset prevention layer (coating layer) is sequentially formed is disclosed.

In the fixing roller having such a configuration,
A heat generating layer is provided on the fixing roller itself, so that the fixing roller generates heat, so that the heat conversion efficiency and the heat transfer efficiency are excellent. It is said that since there is no heat radiation through the air at the time of heating, the rise at the start of heating is fast, and the warm-up time can be shortened.

However, in the fixing roller disclosed in JP-A-59-46668, the heat capacity of the fixing roller has not yet been reduced due to the problem of strength.

Here, it is generally considered that the reduction of the heat capacity of the fixing roller is more effective in shortening the warm-up time than in improving the heat conversion efficiency and the heat transfer efficiency and preventing the air from radiating to the hollow portion. ing. In particular, in a color fixing roller, a thick (1)
２2 mm) silicone rubber layer is commonly used,
The heat capacity of the coating layer is often larger than that of the core metal.

Therefore, it is essential to reduce the heat capacity of the coating layer in order to reduce the warm-up time. However, the above configuration of the fixing roller has not improved this point at all.

In the fixing device, a pressure roller is used which has an elastic layer on the surface and which secures a predetermined nip width by being pressed against the fixing roller. At this time, the decrease in the heating efficiency due to the heat diffusion from the fixing roller to the pressure roller is also a bad effect for shortening the warm-up time of the fixing device, but the roller having the above configuration does not have elasticity. Therefore, it cannot be applied to a roller requiring such elasticity.

Japanese Patent Application Laid-Open No. 8-129313 discloses an elastic layer provided inside and a thickness of 10-15 mm outside.
A configuration is described in which a heating roller provided with a 0 μm metal sleeve heats the metal sleeve from the outside.

[0013] In this configuration, since the heating roller is formed of a thin metal sleeve, the heat capacity can be reduced, so that the warm-up time can be shortened. It is said that it is excellent in durability because it is fixed on the elastic layer fixed to the elastic layer.

[0014]

However, in the fixing roller disclosed in JP-A-8-129313, although the metal sleeve is very thin and has a very small heat capacity, the heat applied to the metal sleeve cannot be reduced. Or, in order to escape the heat generated in the metal sleeve to the internal elastic layer, for example, the hollow core is made of iron to have a thickness of 0.3 to 0.3 mm.
The heating efficiency was lower than that of a conventional fixing roller in which the thickness was reduced to about 0.5 mm, and as a result, the warm-up time hardly changed.

In particular, when an adhesive is used for fixing the metal sleeve and the elastic layer, the heat capacity of the adhesive is added to the heat capacity of the metal sleeve, so that the apparent heat capacity of the metal sleeve increases, and the elastic layer has an increased heat capacity. Since the thermal conductivity is improved, the heating efficiency is further deteriorated. There was such a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a roller having excellent elasticity and heat insulation, which can be applied to a roller requiring elasticity, which is excellent in heat insulation, has a fast rise by heating, and a heating device using the same. It is.

[0017]

The present invention has the following arrangement.

(1) A roller including a core material including a central axis, an elastic layer formed on the outer periphery of the core material, and a metal sleeve formed on the outer periphery of the elastic layer. Is characterized by being a foam having a plurality of air bubbles, each air density being lower than the air density in the atmosphere, while being sealed by a covering member including the metal sleeve provided on the outer periphery thereof.

In this configuration, the elastic layer is sealed by a covering member including the metal sleeve provided on the outer periphery thereof, and a plurality of air layers each having an air density lower than the air density in the atmosphere. Since the foam has bubbles, the air density in the bubbles of the foam during the production of the roller is kept low for a long period of time.

Further, when the air density is low, the heat is hardly transmitted through the air in the air bubbles, so that the heat insulating property of the entire elastic layer is improved.

(2) A part or all of the plurality of bubbles are continuous bubbles.

In this configuration, the plurality of bubbles are:
Since some or all of the cells are open cells, each cell is continuous up to the inside of the foam layer constituting the elastic layer, so that the bubbles of the foam in the elastic layer are evacuated or the like. The work of lowering the air density is facilitated.

(3) A part or all of the plurality of bubbles are closed cells.

In this configuration, the plurality of bubbles are:
Since some or all of the cells are closed cells, the airtightness of each bubble is high and the air flow is very small,
The roller can be easily handled in the sealing operation of the elastic layer after the air density of the bubbles is reduced.

(4) The plurality of air bubbles are characterized in that a part or the entire diameter thereof is equal to or less than the mean free path of air.

In this configuration, the plurality of bubbles are:
Since some or all of the diameters are less than the mean free path of air, gas molecules remaining in the bubbles rarely collide with other gas molecules, so that heat conduction through the gas is not sufficient. And the heat insulating property is improved as a whole of the elastic layer.
The mean free path refers to the distance that gas molecules fly freely without colliding with other molecules, and it is said that the shorter this distance is, the more heat conduction of the gas becomes active.

(5) The core material is a hollow shaft, and is provided with a plurality of through holes for communicating the contact surface with the elastic layer and the inside of the core material.

In this configuration, the core material is a hollow shaft, and a plurality of through-holes are provided for communicating between the contact surface with the elastic layer and the inside of the core material. Bubbles communicate with the outside through the through-holes and hollow portions of the core material. For this reason, the work of lowering the air density from outside using the hollow part and the through hole of the core material, the work of sealing the elastic body layer,
In addition, the re-deaeration work after the elapse of the predetermined period can be easily performed.

Further, since the deaeration process is performed uniformly in the axial direction of the shaft, the degree of vacuum of the bubbles is made more uniform.

(6) The core material has an air-absorbing agent which absorbs air in a hollow portion thereof.

In this structure, since the core material has an air-absorbing agent in its hollow portion for absorbing air, it may be used if air remains in the air bubbles after the air density lowering operation or if it is used for a long time. Therefore, even when air enters the air bubbles, the air-absorbing agent absorbs the air, and the air density in the air bubbles that contributes to the conduction of heat is reduced, so that the heat insulation of the entire elastic layer is improved.

(7) The end surface of the elastic layer is sealed integrally with the metal sleeve to be a heat generating layer by a flexible sealing material.

In this configuration, since the end surface of the elastic layer is sealed integrally with the metal sleeve serving as the heat generating layer by a flexible sealing material, the sealing material is sealed. The elastic effect of the elastic layer is not impaired.

Further, since the sealing material is integrated with the heat generating layer, even if the heat generating layer is not bonded to the foamed elastic material layer, displacement of the heat generating layer is prevented, and the heat generating layer is moved from the heat generating layer to the foamed elastic material layer. Thermal diffusion is effectively prevented.

(8) The sealing material is a silicon-based adhesive.

In this configuration, since the sealing material is a silicone-based adhesive, it has flexibility.
Since the heat resistance is also excellent, the elastic effect of the elastic layer is not impaired, and even when the metal sleeve generates heat, it can withstand the temperature of the metal sleeve, so that the function as a sealing material is sufficiently ensured.

Further, since the adhesiveness to the silicone rubber which is usually used as the elastic layer is excellent, the adhesion of the sealing material is improved.

(9) Rollers according to (1) to (8)
It is characterized in that it is used for at least one of a heating roller and a pressure roller.

In this configuration, since the above-described roller having elasticity and heat insulation is applied to a heating device such as a fixing device, for example, a metal sleeve is heated to fix an unfixed toner image on paper. In this case, since the heat insulating property of the elastic body layer in contact with the heat generating layer is high, the heat generated in the heat generating layer does not easily escape to the elastic body layer, and the heat efficiency is improved, so that the so-called warm-up time of the heating device is shortened.

Further, since the diameter of these rollers is prevented from being changed due to the thermal expansion of the air in the bubbles in the elastic layer, there is a problem in that the processing of the medium to be heated and the like to be processed by these rollers occurs. For example, it is possible to prevent wrinkles from occurring on the conveyed sheet.

(10) In a heating device including a heating belt stretched over one or more rollers, a pressure roller pressed against the heating belt, and heating means for heating the heating belt, At least one
A roller according to any one of (1) to (8).

In this configuration, a heating belt stretched around one or a plurality of rollers having the above-described elastic and heat insulating properties, a pressure roller pressed against the heating belt, and the heating belt are heated. Since the present invention is applied to a heating device provided with a heating means, the heat of the heating belt is hardly released to these rollers serving as a support member of the heating belt, so that the heat efficiency of the heating device is improved and the so-called warming-up time is shortened.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

An embodiment in which the heating device of the present invention is applied to a fixing device in a dry electrophotographic apparatus will be described.

FIG. 1 shows a part of the configuration of an image forming apparatus to which the present invention is applied.

The dry electrophotographic color image forming apparatus to which the present invention is applied is a so-called tandem type printer in which four color image forming units 10 are arranged along a recording medium conveying path as shown in FIG. is there.

The supply tray 20 for the sheet 72 to be heated
A set of four image forming units 10Y, 10M, 10C, and 10B is arranged along a paper conveyance path connecting the paper and the fixing device 1, and each color toner is conveyed to the paper 72 conveyed by the paper conveyance means 30 of an endless belt. Is transferred by the fixing device 1 to form a full-color image.

The recording paper transporting means 30 has an endless transport belt 33 which is stretched by a driving roller 31 and an idling roller 32 and rotates at a controlled peripheral speed. The paper 72 is electrostatically attracted and transported.

Each image forming unit 10 has a photosensitive drum 11 carrying an image and a charging roller 1 around the photosensitive drum 11.
2, a laser scanner unit 13, a developing device 14, a transfer roller 15, and a cleaning device 16 are arranged. The developing device 14 of each image forming unit 10 includes yellow (Y), magenta (M), and cyan (M ) And black (B) toners.

Then, each image forming unit performs an image forming process of forming a toner image on the paper 72 by the following steps.

Specifically, after the surface of the photosensitive drum 11 is uniformly charged by the charging roller 12, the surface of the photosensitive drum 11 is exposed by the laser scanner unit 13 in accordance with image information to form an electrostatic latent image. I do.

Thereafter, toner is supplied to the surface of the photosensitive drum 11 by the developing device 14 to visualize the electrostatic latent image into a toner image, and the visualized toner image is subjected to a bias voltage having a polarity opposite to that of the toner. Is applied by the transfer roller 15 to which
The image is sequentially transferred onto the sheet 72 conveyed on the conveying means.

Thereafter, the sheet 72 is separated from the conveyor belt by the curvature of the drive roller 31 and is conveyed to the fixing device 1. In this fixing device, an appropriate temperature and pressure are given by a heating roller maintained at a predetermined temperature,
The unfixed toner 71 is melted and fixed to the sheet 72 to form a robust image.

FIG. 2 is a diagram showing the structure of the fixing device of the present invention. The fixing device 1 includes a heating roller 50 that heats the toner 71 on the paper to be guided to melt the paper, a pressure roller 60 that applies a predetermined pressure to the paper to fix the toner image, and a heating roller 50 that heats the paper. Excitation circuit 42 for generating a magnetic field of the same and driving means 44 for rotatingly driving heating roller 50
And a control circuit 43 for controlling the operation of the fixing device 1.

In the fixing device 1, a heating roller 50 having a metal sleeve 46 as a heat generating layer is heated by a magnetic field generating means 41 which is a heating means disposed outside the heating roller 50, and the heating roller 50 heated at a constant temperature is heated. The image is fixed on the sheet by passing the sheet having the unfixed toner image through the nip portion with the pressure roller 60.

The heating roller 50 is composed of an elastic layer made of foamed silicone rubber on a metal core 40 made of a metal such as aluminum, iron or stainless steel (a core material, preferably aluminum in order to prevent heat generated by induction heating). 47 and a metal sleeve 46 are sequentially formed.

The metal sleeve 46 is a heating element that generates heat by a dielectric heating action. The thickness of the metal sleeve 46 is reduced to 40 μm to 50 μm in order to shorten the rise time of the surface temperature.

The material of the base material of the metal sleeve 46 is made of iron, SUS430 stainless steel, etc., for heating by induction heating.
Any conductive member having magnetism may be used. In particular, it is sufficient that the relative magnetic permeability is high, and a silicon steel sheet, an electromagnetic steel sheet, a nickel steel, or the like may be used.

Further, even if it is a non-magnetic material, SUS304
Any material having a high resistance such as stainless steel can be used because it can be induction-heated. Further, even a non-magnetic metal sleeve 46 such as ceramics can be employed as long as the material having high non-magnetic permeability is arranged to have conductivity.

Here, nickel having a thickness of 40 μm produced by electroforming is used for the base material of the metal sleeve 46. Further, in order to increase the calorific value, the metal sleeve 46 is used.
May be constituted by a sleeve composed of a plurality of layers.

Further, on the outer peripheral surface of the metal sleeve 46, polytetrafluoroethylene (hereinafter, referred to as PTFE) is used in order to prevent the toner 71 heated in the nip 70 and having reduced viscosity from adhering to the heating roller 50. ), A fluororesin such as a copolymer of tetrafluoroethylene and perfluoroalkylvinylether (hereinafter referred to as PFA), or an elastic body such as silicon rubber, fluororubber, or fluorosilicone rubber, or a laminate of a plurality of these layers. The mold layer 45 is covered.

In this embodiment, the coating layer has a thickness of 150 μm.
m of the silicone rubber layer. As described above, the metal sleeve 46 is very thin, and does not provide sufficient mechanical strength by itself.

Therefore, the heating roller 50 in this embodiment is
In order to fix and support the metal sleeve 46, the elastic layer 4 made of a foamed elastic material is provided inside the metal sleeve 46.
7 are provided. The elastic layer 47 is made of foamed silicone rubber having excellent heat insulation and heat resistance so as to minimize heat escape from the metal sleeve 46 and withstand the temperature of the metal sleeve 46. For example, a 6 mm one is used.

The pressure roller 60 for forming the nip 70 for contacting the heating roller 50 and passing the sheet is
An elastic layer 47 made of silicon rubber or the like is provided on a core metal 40 made of iron, stainless steel, or aluminum.

A release layer 45 made of PFA or PTFE may be formed on the surface of the pressure roller 60.

The pressure roller 60 is pressed against the heating roller 50 by an elastic member such as a spring (not shown), whereby a contact nip 70 having a width of about 6.5 mm is formed between the pressure roller 60 and the heating roller 50. .

The magnetic field generating means 41, which is an induction heating means for heating the heating roller 50, is constituted by the induction coil shown in FIG. 3, and is configured to surround the outer periphery of the heating roller 50. With such a configuration, since the curvature exists, the magnetic flux concentrates on the center side of the induction coil, and the amount of eddy current generated increases. Therefore, it is convenient to quickly raise the surface temperature of the heating roller 50.

As the material of the induction coil, a single aluminum wire having a surface insulating layer such as an oxide film is used in consideration of heat resistance, but it is a copper wire or a copper-based composite member wire. Alternatively, a litz wire formed by twisting an enamel wire or the like may be used.

Whichever wire is used, the total resistance of the induction coil should be 0.5 Ω or less, preferably 0.1 Ω or less, in order to suppress Joule loss in the coil. Also, a plurality of induction coils may be arranged according to the size of the paper to be fixed.

The induction coil shown in FIG.
The heating roller 50 is induction-heated by an alternating magnetic field generated by flowing a higher frequency current from the heating roller 50. At this time, the thermistor 48 is arranged near the nip 70,
CPU (not shown) according to the detection signal of the thermistor 48
The control means including the above controls the excitation circuit, whereby the temperature of the heating roller 50 is controlled to a constant temperature.

The unfixed image is passed through the nip 70 by rotating the heating roller 50 controlled at a constant temperature by the driving means 43, and the image is fixed on the paper by heat and pressure. . At this time, an anti-offset agent made of silicone oil or the like may be applied to the surface of the heating roller 50 according to the characteristics of the toner 71.

Next, the heating roller 50 will be described with reference to FIG.

FIG. 4 shows a heating roller 50 according to this embodiment.
FIG. As described above, the elastic layer 47 is made of foamed silicone rubber. Usually, the foamed silicone rubber has air having the same density as that of the atmosphere inside the air bubbles 52. In this case, the thermal conductivity of the foamed silicone rubber
It is about 0.07 (W / m ° C), which is larger than the thermal conductivity of air, 0.0257 (W / m ° C), and has poor heat insulation. Is a conventional heating roller 5 using a hollow metal core 40.
At 0, it is known that the heat amount is larger than the amount of heat released from the core metal 40 to the air in the hollow portion.

In such a case, the characteristics and effects of the heating roller 50 of the present invention, in which the heating element has a reduced heat capacity, are offset by using the thin metal sleeve 46, and the warm-up time is longer than that of the conventional heating roller. It is almost the same as a heating roller in which the core metal 40 is thinned by using an iron-based material which is superior in strength to aluminum, for example, as the material of the core metal 40 in the mold.

Here, generally, about 60% of the heat escaping to the elastic layer 47 is the heat transmitted to the elastic material, that is, the silicon rubber itself in the present embodiment, and the remaining about 40% is the elastic foam. It is said to be heat transmitted through air in air bubbles in the body.

Therefore, if the air density inside the bubbles 52 of the foamed silicone rubber is made lower than the air density in the atmosphere, the thermal conductivity of the foamed silicone rubber can be lowered, and the heat insulating property of the elastic layer 47 can be further improved. Can be improved.

Therefore, the heating roller 5 in this embodiment is
In the case of No. 0, the air inside the bubbles 52 of the foamed silicone rubber which is the elastic layer 47 is deaerated during the manufacturing process. Specifically, a roller in which the elastic layer 47 is formed on the cored bar 40 (hereinafter, referred to as an elastic roller) is manufactured.
Also, the release layer 4 is formed on the metal sleeve 46 in a separate step.
5 is formed, and an elastic roller is inserted into the metal sleeve 46 by using a heating roller 50 manufacturing apparatus.

Then, the elastic roller is put in a vacuum device with the metal sleeve 46 covered, and air present inside the bubbles of the elastic layer 47 is degassed from the end of the elastic layer 47. After the degassing is completed, the end of the elastic layer 47 is integrally sealed with the metal sleeve 46 using the sealing material 51, and the elastic layer 47 is sealed.

Here, since the elastic layer 47 must be deformed by pressure contact with the pressure roller 60 to form a nip, the material used for the sealing material 51 has flexibility and elasticity. The elastic layer 47 must be deformed following the deformation of the layer 47, and has heat resistance enough to withstand the temperature of the heated metal sleeve 46 because the elastic layer 47 is sealed integrally with the metal sleeve 46. Is more desirable.

Therefore, in this embodiment, the sealing material 51 is used.
As a silicone adhesive. Silicone adhesives have flexibility and also have excellent heat resistance,
It is suitable as the sealing material 51.

When it is desired to improve the degassing efficiency and the degree of vacuum inside the bubbles as much as possible, the structure of the bubbles 52 is made of silicone rubber so that a part or all of the bubbles are connected. It is good to set foaming conditions. Elastic layer 47
With such a configuration, the time required for degassing is reduced, and the degree of vacuum inside the bubbles is further increased. When the thermal conductivity of the elastic layer 47 of the heating roller 50 manufactured as described above was measured, the value was 0.05 (W / m ° C.). It was confirmed that the heat insulating property was improved as compared with the value of the thermal conductivity of 0.072 (W / m ° C.).

On the other hand, when it is desired to improve the workability when shielding, the foaming condition of the silicone rubber is set as the structure of the bubble 52 so that a part or all of the bubble is in an independent closed state. good. Although closed cells have some degree of airtightness, they do not have perfect confidentiality.When left in a vacuum device, it takes more time than open cells, but the gas inside the bubbles is gradually sucked in. Degassed.

After the degassing, even if the elastic roller is taken out into the atmosphere, it takes time for the gas to enter the air bubbles again, so that a vacuum state is maintained to some extent even before the shielding operation. As a result, the shield work with the sealing material can be performed in the atmosphere outside the vacuum device, and the workability can be improved.

After the closed-cell elastic roller is degassed by a vacuum device for 30 minutes and then taken out of the vacuum device and shielded for about 3 minutes, the heat conductivity is equal to that of the roller processed in the vacuum device. 0.05 (W / m ° C).

Further, in order to improve the productivity of the elastic roller according to the present invention, it is necessary to shorten the deaeration time as much as possible. Will remain. Generally, a vacuum pressure that can be easily obtained industrially is about 0.5 Torr. Even in such a case, the average diameter of the bubbles is preferably smaller than the mean free path of air in order to maintain the heat insulation of the elastic roller as much as possible. The mean free path is
This is the distance over which gas molecules fly freely without colliding with other molecules. The shorter the distance, the more heat conduction of the gas becomes active. The mean free path is generally represented by the following equation.

L = 2.33 × 10 ⁻²⁰ T / (P × σ ² ) L: mean free path (cm) T: temperature (K) P: pressure (Torr) σ: gas molecule radius (cm) When the distance between the walls formed by the bubbles, that is, the distance between the air gaps is shorter than the mean free path, the probability that the gases collide with each other is almost negligible, and the heat insulating property is improved. Therefore, in this embodiment, the average cell diameter is set to 100 μm, which is smaller than the mean free path of air (about 130 μm in the case of this embodiment).

FIG. 5 is a front sectional view of the heating roller 50 in the second embodiment of the heating device 1 according to the present invention. Note that, in the present embodiment, the configuration other than the heating roller 50 is the same as the configuration in the first embodiment.

Further, the heating roller 5 in the present embodiment
Reference numeral 0 denotes the same configuration as that of the first embodiment except for the cored bar 40. However, the core metal 40 has a hollow cylindrical shape made of aluminum, and is penetrated from the outer surface to the inner surface.
The third embodiment is different from the first embodiment in having a large number of through holes 49 communicating the elastic layer 47 and the hollow portion of the metal core 40.

Next, a method of manufacturing the heating roller 50 will be described. A roller (hereinafter, referred to as an elastic roller) in which the elastic layer 47 is inserted and adhered to the cored bar 40 is manufactured, and a release layer 45 is formed on the metal sleeve 46 in a separate process.
Is formed, and an elastic roller is inserted into the metal sleeve 46 using the heating roller 50 manufacturing apparatus.

Next, the end of the elastic layer 47 is sealed with a metal sleeve 46 using a sealing material 51 made of a silicone-based adhesive.
Are integrally sealed. And this metal sleeve 46
Then, the elastic roller is put in a vacuum device in a state where it is covered, and vacuuming is performed. As a result, the air existing inside the bubbles of the elastic layer 47 flows from the bubbles 52 through the through-holes 49 of the core bar 40 and from the through-holes 49 of the core bar 40 through the hollow portions to the openings at both ends of the core bar 40. It is degassed by the route. After the degassing is completed, the shield caps 53 are inserted into the openings at both ends of the metal core 40 to seal the inside of the metal core 40. Thereafter, the heating roller 50 is taken out of the vacuum device. Then, due to the pressure difference between the inside and outside of the core bar 40, the shield cap 53 is
It is strongly pressurized to 0, and the sealing performance inside the cored bar 40 is further improved.

With the above-described configuration of the heating roller 50, usually, a very labor-intensive and time-consuming operation in a vacuum device is required.
This is a simple operation that can be easily performed even in a vacuum apparatus in which only a gas is inserted. In the heating roller 50 having this configuration, the sealing operation with the sealing material 51 can be performed outside the vacuum device before the deaeration process, so that the productivity can be improved.

In the heating roller 50 according to the first embodiment, since the air is degassed from the end of the elastic layer 47, the degree of vacuum inside the bubble is likely to be uneven at the end and the center of the heating roller 50.
On the other hand, in the heating roller 50 of the present embodiment, since the degassing process is performed uniformly in the axial direction, the degree of vacuum of the bubbles can be made more uniform.

When the heating roller 50 is used for a long time,
It is conceivable that air gradually penetrates into the bubbles and the heat insulation property is reduced. Even in such a case, in the heating roller 50 of the present embodiment, since the shield cap 53 can be removed, the heat insulating property can be restored by performing the degassing process again in the vacuum device. Can be used over a period of time.

Further, by inserting in advance a getter agent which is an inhalant such as activated carbon, calcium hydroxide, calcium chloride, zeolite, silica-based fine powder or the like into the core metal 40, air bubbles may be slightly generated due to long-term use. Even if air enters the interior, the air is absorbed by the getter agent, so that heat insulation can be maintained for a long time.

FIG. 6 is a diagram showing the use state of the elastic roller according to the present invention. FIG. 1 shows an example in which the elastic roller according to the present invention is applied to a pressure roller 60 of a heat roller fixing device. In the present embodiment, the heat roller fixing device 1 is in pressure contact with a heat roller 50 in which a release layer 45 made of a fluororesin or the like is provided on the surface of a hollow metal core 40 made of a metal such as aluminum or iron. A pressure roller 60 is provided, and the heating roller 50 is heated by infrared rays from a heater 54 such as a halogen lamp disposed inside the heating roller 50.

The heating roller 5 is provided around the heating roller 50.
A temperature sensor 48 including a thermistor or the like for detecting the surface temperature of the heating roller 50 and controlling the temperature to a predetermined temperature on the upstream side of the nip 70 serving as an abutting portion of the nip 70 with the pressure roller 60. A peeling claw 55 for preventing the paper from being wound around the heating roller 50 is provided on the downstream side, and a safety device 56 such as a thermostat for preventing abnormal heating of the heating roller 50 is disposed above the heating roller 50. Have been.

FIG. 7 shows the structure of the pressure roller 60 applied to this embodiment.

The pressure roller 60 is constructed by integrally sealing an elastic layer 47 made of foamed silicone rubber and a PFA tube on a core metal 40 made of metal such as iron or stainless steel by a sealing member 51. I have. For this reason,
The elastic layer 47 is in a closed state.

The pressure roller 60 manufactured as described above is used.
The thermal conductivity of the elastic layer 47 was measured to be 0.05
(W / m ° C.), which is better than the heat conductivity value of 0.072 (W / m ° C.) of the pressure roller that has not been subjected to the deaeration treatment. As a result, the amount of heat that escapes from the heating roller 50 to the pressure roller 60 can be reduced, so that the warm-up time of the fixing device can be reduced, and the thermal efficiency during the fixing operation can be improved.

FIG. 8 is a diagram showing a state in which the elastic roller according to the present invention is applied to the heating roller 50 of the belt fixing device. The belt-type fixing device according to the present embodiment includes a heating roller 50, a backup roller 8 as a support member.
0, a pressure roller 60, a tension roller 80, an endless belt 59 as a heating belt, a heater 54, and a temperature sensor 48.

The endless belt 59 has a double structure in which a release layer 45 is coated on the outer surface of a metal substrate such as nickel or stainless steel having a thickness of 40 μm and covered with silicon rubber, fluororesin, or the like. And around the heating roller 50 at a winding angle close to 180 °.

The tension roller 58 has a heat-resistant coating layer made of, for example, aluminum, iron, stainless steel, or the like, made of, for example, Nomex felt (registered trademark) impregnated with silicon oil on the surface of the metal core 40, and is spirally attached. In addition to applying a predetermined tension to the endless belt 59, the endless belt 59 is also used for cleaning and oil application.

The heating roller 50 has a metal hollow core 40 made of aluminum, iron, stainless steel or the like, on the surface of which a coating layer made of fluoro rubber is formed, and inside the heating roller 50 a heater 54 made of a halogen lamp. Is arranged. A thermistor 48, which is a temperature sensor, is in contact with the surface of the heating roller 50 opposite to the contact area with the endless belt 59, and detects the surface temperature of the heating roller 50.

The pressure roller 60 has a structure in which an elastic layer 47 made of silicon rubber is provided on a metal core bar 40 made of aluminum, iron or stainless steel, and a backup roller is provided via an endless belt 59 by a coil spring (not shown). The nip portion 70 having a predetermined width is formed by pressing against the nip portion 80.

In the fixing device 1 configured as described above, the heating roller 50 is controlled to be heated to a predetermined temperature by the heater 54, and is rotated by driving means (not shown). Then, following the rotation of the heating roller 50, the endless belt, the backup roller, and the pressure roller 60 rotate, and the sheet on which the unfixed toner image is formed is conveyed to the nip 70, whereby the fixing is performed.

Next, a backup roller to which the present invention is applied will be described with reference to FIG. The backup roller has a configuration in which an elastic layer 47 made of foamed silicone rubber and a coating layer made of a PFA tube are sequentially formed on a metal core 40 made of metal such as iron or stainless steel. Also, during the manufacturing process, air present inside the bubbles in the elastic layer 47 is subjected to degassing by a vacuum device, and after degassing,
After the deaeration is completed so that air does not enter the air bubbles again, the end of the elastic layer 47 is integrally sealed with the PFA tube with a sealing material, whereby the elastic layer 47 is sealed. I have.

When the thermal conductivity of the elastic layer 47 of the backup roller manufactured as described above was measured,
5 (W / m ° C.), which is 0.072 which is the value of the thermal conductivity of the conventional backup roller not subjected to the deaeration treatment.
(W / m ° C), it was confirmed that the heat insulating property was improved.

As a result, the amount of heat escaping from the endless belt 59 to the backup roller 80 can be reduced, the warm-up time of the fixing device 1 can be shortened, and the thermal efficiency during the fixing operation can be improved.

Next, the results of actual measurement of the warm-up time (temperature rise characteristic) and the power consumption by the fixing device 1 using the elastic roller according to the present invention will be described. The fixing device 1 actually used uses the elastic roller of the present invention for both the heating roller 50 and the pressure roller 60 as shown in FIG.

FIG. 11 shows that the input power 80
It shows the measurement results of the warm-up time when the roller speed is 0 W and the roller peripheral speed is 200 mm / s.

The time required to raise the fixing temperature to 190 ° C., the so-called warm-up time, is 14.6 seconds for the fixing device of the present embodiment and 18.6 seconds for the fixing device of the comparative example. Further, it is shown that the warm-up time is reduced by about 20% by achieving vacuum insulation of the elastic roller.

[0112] Also, the warm-up and 1
The power consumption when the temperature is controlled at 90 ° C. for 30 seconds is as follows: the power consumption during warm-up is 0.89 Wh, and 19
Power consumption during temperature control for 30 seconds at 0 ° C is 0.4
It has been found that the power consumption is also reduced by reducing the thermal insulation of the elastic roller of the fixing device by 2 Wh.

[0113]

As described above, according to the present invention, (1) the elastic layer is sealed by the covering member including the metal sleeve provided on the outer periphery thereof, and
Since each of the air densities is a foam having a plurality of cells lower than the air density in the atmosphere, the air density in the cells of the foam during the production of the roller is kept low for a long time. Can be.

When the air density is low, heat is less likely to be transmitted through the air in the air bubbles, so that the heat insulating property of the entire elastic layer can be improved.

(2) Since some or all of the plurality of cells are open cells, the cells are continuous up to the inside of the foam layer constituting the elastic layer. The work of lowering the air density by evacuation of bubbles of the foam in the elastic layer can be easily performed.

(3) Since some or all of the plurality of bubbles are closed cells, the airtightness of each bubble is high and the air flow is minute, so that the air density of the bubbles is reduced. The handling of the roller in the subsequent sealing work of the elastic layer and the like can be facilitated.

(4) Since some or all of the plurality of bubbles have a diameter equal to or less than the mean free path of air, gas molecules remaining in the bubbles rarely collide with other gas molecules. Because, it is difficult to conduct heat through the gas,
Heat insulation can be improved as the whole elastic layer.

(5) The core material is a hollow shaft, and a plurality of through-holes are provided for communicating the contact surface with the elastic layer and the inside of the core material. To communicate with the outside through the through hole and the hollow portion of the core material, the work of lowering the air density from the outside using the hollow portion and the through hole of the core material, the work of sealing the elastic layer, and after a predetermined period has elapsed Can be easily performed again.

Further, since the deaeration process is performed uniformly in the axial direction of the shaft, the degree of vacuum of the bubbles can be made more uniform.

(6) Since the core material has an air-absorbing agent in its hollow portion to absorb air, the air bubbles may remain if air remains in the air bubbles after the air density lowering operation or if the air bubbles are used for a long period of time. Even when air enters the inside, the air-absorbing agent absorbs the air, and the air density in the air bubbles contributing to the conduction of heat is reduced, so that the heat insulation of the entire elastic layer can be improved. .

(7) Since the end surface of the elastic layer is sealed integrally with the metal sleeve serving as the heat generating layer by a flexible sealing material, the elastic material is sealed by sealing the sealing material. The elastic effect of the layer can be prevented from being impaired.

Further, since the sealing material is integrated with the heat generating layer, even if the heat generating layer is not bonded to the elastic foam layer, the heat generating layer is prevented from being displaced, and the heat generating layer can be moved from the heat generating layer to the foam elastic layer. Thermal diffusion can be effectively prevented.

(8) Since the sealing material is a silicone-based adhesive, it has flexibility and excellent heat resistance, so that the elastic effect of the elastic layer is not impaired, and the heat generation of the metal sleeve is not affected. Even at the time, since the temperature of the metal sleeve can be endured, the function as the sealing material can be sufficiently ensured.

Further, since the adhesiveness to silicon rubber which is usually used as the elastic layer is excellent, the adhesion of the sealing material can be improved.

(9) Since the roller having elasticity and heat insulation described above is applied to a heating device such as a fixing device, for example, when a metal sleeve is heated to fix an unfixed toner image on paper. Since the heat insulating property of the elastic layer in contact with the heat generating layer is high, the heat generated in the heat generating layer does not easily escape to the elastic layer, the thermal efficiency is improved, and the so-called warm-up time of the heating device can be reduced.

Further, since the diameter of these rollers is prevented from changing due to the thermal expansion of the air in the air bubbles in the elastic layer, the processing of the medium to be heated or the like processed by these rollers is prevented. For example, it is possible to prevent wrinkles from occurring on the conveyed paper.

(10) A heating belt having the above-mentioned elastic and heat-insulating rollers stretched over one or more rollers, a pressure roller which presses against the heating belt, and a heating means for heating the heating belt Since the present invention is applied to a heating device having a heating belt, the heat of the heating belt is hardly released to these rollers serving as a support member of the heating belt, the thermal efficiency of the heating device is improved, and the so-called warm-up time can be reduced. .

Therefore, it is possible to provide a roller having excellent heat insulating properties, quick rise by heating, and having elasticity and heat insulating properties applicable to rollers requiring elasticity, and a heating device using the same.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus to which the present invention is applied.

FIG. 2 is a diagram showing an example of a configuration of a heating device of the present invention.

FIG. 3 is a diagram showing a configuration of a heating means of the present invention.

FIG. 4 is a diagram illustrating an example of a configuration of a heating roller of the present invention.

FIG. 5 is a diagram illustrating an example of a configuration of a heating roller of the present invention.

FIG. 6 is a diagram showing a use state of the pressure roller of the present invention.

FIG. 7 is a diagram illustrating an example of a configuration of a pressure roller of the present invention.

FIG. 8 is a diagram illustrating a use state of the elastic roller of the present invention.

FIG. 9 is a diagram illustrating an example of a configuration of a backup roller of the present invention.

FIG. 10 is a diagram showing a use state of the elastic roller of the present invention.

FIG. 11 shows a measurement result of a warm-up time in the present invention.

[Explanation of symbols]

 1-Fixing device 40-Core 41-Heating means 42-Exciting circuit 43-Control means 44-Drive means 45-Release layer 46-Metal sleeve 47-Elastic body layer 48-Temperature sensor 49-Through hole 50-Heating roller 60-pressure roller

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H05B 3/00 335 H05B 3/00 335 6/14 6/14 F term (reference) 2H033 AA30 BA11 BA25 BB04 BB14 BB15 BB18 BB29 BB30 BB34 BE06 2H074 AA03 BB68 EE07 3J103 AA13 AA32 AA37 AA51 AA81 BA02 FA01 FA20 GA02 GA57 GA58 GA60 HA03 HA05 HA12 HA18 HA22 HA31 HA41 3K058 AA01 AA87 BA18 CA12 CA61 DA02 DA26 3K059 AC33 AD02 CD53

Claims (10)

[Claims] 1. A roller comprising a core material including a central axis, an elastic layer formed on an outer periphery of the core material, and a metal sleeve formed on an outer periphery of the elastic layer, wherein the elastic layer is Elasticity characterized by being a foam having a plurality of air bubbles, each air density of which is sealed by a covering member including the metal sleeve provided on the outer periphery thereof and each air density is lower than the air density of the atmosphere. Roller with heat insulation. 2. The roller with elasticity and heat insulation according to claim 1, wherein a part or all of the plurality of bubbles are open cells. 3. The roller according to claim 1, wherein a part or all of the plurality of bubbles are closed cells. 4. The elasticity and heat insulating property according to claim 1, wherein the plurality of bubbles have a diameter of a part or the whole thereof is equal to or less than a mean free path of air. roller. 5. The core material according to claim 1, wherein the core material is a hollow shaft, and a plurality of through holes are provided to allow a contact surface with the elastic layer to communicate with the inside of the core material. 5. The roller having elasticity and heat insulation described in any one of 4. 6. The roller with elasticity and heat insulation according to claim 5, wherein said core material has a suction agent for absorbing air in a hollow portion thereof. 7. An end face of said elastic body layer is sealed integrally with said metal sleeve as a heating layer by a flexible sealing material.
The roller having elasticity and heat insulation described in any one of the above. 8. The roller having elasticity and heat insulation according to claim 7, wherein the sealing material is a silicone-based adhesive. 9. A heating device, wherein the roller according to claim 1 is used for at least one of a heating roller and a pressure roller. 10. A heating device comprising: a heating belt stretched over one or more rollers; a pressure roller in pressure contact with the heating belt; and heating means for heating the heating belt. A heating device, one of which is the roller according to any one of claims 1 to 8.