JPH06250554A - Fixing method and fixing device - Google Patents

Abstract

PURPOSE:To reduce power consumption, downsize a fixing device by the diameter reduction of a roller, and shorten warm-up time (waiting time). CONSTITUTION:In a fixing method for heating, pressurizing and fixing a toner image 4 on a recording medium 3 between the contact surfaces of a pair of rollers 1, 2 rotating in contact with each other, at least one of the rollers 1, 2 has a conductive elastomer layer 1b having a specific resistance of 0,1-100OMEGAcm on the surface of a cylindrical insulating roller base la, and the heating of the roller 1 is conducted by the current application to the elastomer layer 1b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fixing for fixing a toner image transferred on a recording medium used in an image forming apparatus utilizing an electrophotographic process such as an electrostatic copying machine, a printer, a facsimile and the like. The present invention relates to a method and a fixing device.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed and put into practical use for fixing devices in image forming apparatuses utilizing an electrophotographic process. It is the mainstream. Among them, a heat roller fixing method in which a heating roller directly contacts an image support to conduct heat is known as a typical method.
In this method, at least one of a pair of rollers has a hollow roller inside which has a heat source such as a halogen lamp heater, and the other has a pressure roller in which an elastic layer such as rubber is formed on the surface layer. They are made of a pair of nip widths and come into contact with each other with an appropriate nip width, and are appropriately driven by a driving means to rotate.

However, since the conventional heat roller fixing device has a heat source inside, the inner diameter of the heat roller is required to some extent, and the size of the fixing device cannot be reduced. Further, since the roller is heated by the radiant heat from the halogen lamp heater or the like, there is a lot of heat loss and a relatively large power consumption. Therefore, when the power of the normal image forming apparatus is turned on, the time until the surface temperature of the heating roller reaches a predetermined temperature, that is, the so-called warm-up time (standby time), becomes relatively long.

With respect to these problems, in recent years, JP-A-55 has
No. 164860, Japanese Patent Laid-Open No. 60-260077, Japanese Patent Laid-Open No. 62-262075, and Japanese Utility Model Laid-Open No. 63-1.
There is proposed a fixing device using a so-called resistance heating element roller having a layered heating portion on the surface layer of the fixing roller or in the vicinity of the surface layer, as described in JP-A-51838 and Japanese Patent Application Laid-Open No. 1-177577. According to these methods,
Since there is no heat source inside the roller, it can be downsized,
Since the roller can be directly heated by Joule heat generated by energization, heat loss is small and low power consumption can be achieved.

However, although a conductive material such as iron or SUS material is usually used as the roller base material of such a heating roller, when such a base material is used, the resistance heating element layer is energized only. In this case, it was necessary to electrically insulate the resistance heating element layer and the base material, and it was necessary to provide an insulating layer between them. Further, since the heat conduction to the roller base material is large, the heat conduction to the roller surface is lowered, and there is a problem that the waiting time until the roller surface temperature reaches a predetermined temperature is not shortened.

[0006] In order to deal with such a problem, Japanese Patent Laid-Open No.
JP-A-326386 proposes a fixing device in which a heating resistor is provided on the surface of a cylindrical insulating roller base material.
However, although it is not necessary to provide an insulating layer on the base material in this device, since the roller base material is cylindrical, when the diameter of the roller is reduced for the purpose of downsizing the device, its bending strength becomes insufficient and the fixing There was a problem that the properties became uneven.

An object of the present invention is to solve the above-mentioned problems, to reduce the power consumption, to downsize the fixing device by reducing the diameter of the heating roller, and to shorten the warm-up time (standby time). An object is to provide a possible fixing method and fixing device.

[0008]

The present inventors have found that the above object can be achieved by a method of heat fixing using a heating roller having a conductive elastomer layer on the surface of a cylindrical insulating roller base material. The present invention has been completed.

That is, the gist of the present invention is (1) in a fixing method in which a toner image on a recording medium is heated and fixed between the contact surfaces of a pair of rollers rotating in contact with each other, at least one of the rollers is fixed. A fixing characterized in that a cylindrical insulating roller base material has a conductive elastomer layer having a specific resistance value of 0.1 to 100 Ωcm on the surface thereof, and heating of the roller is performed by energizing the elastomer layer. Method and (2) In a fixing device comprising at least a pair of rollers rotating in contact with each other, wherein a toner image on a recording medium is heated and pressure-fixed between contact surfaces of the rollers, at least one of the rollers is a circle. It has a conductive elastomer layer having a specific resistance value of 0.1 to 100 Ωcm on the surface of a columnar insulating roller base material, and is provided with an energizing means for energizing the elastomer layer. The fixing device to be collected.

The developer (toner) used in the present invention is not particularly limited, and a pulverized toner obtained by a pulverizing and classifying method, a polymerized toner obtained by a radical polymerization method, a storage stability and a fixing property, It may be any one such as a capsule toner having a function-separated offset resistance.

The fixing method of the present invention is a fixing method in which a toner image formed on such a recording medium on a recording medium is heated and pressure-fixed between the contact surfaces of a pair of rollers rotating in contact with each other. At least one of the rollers has a conductive elastomer layer on the surface of a cylindrical insulating roller base material, and heating of the roller is performed by energizing the elastomer layer. Further, the fixing device of the present invention is for suitably performing the fixing method, and includes at least a pair of rollers that rotate in contact with each other, and heats the toner image on the recording medium between the contact surfaces of the rollers. A fixing device for pressure fixing, wherein at least one of the rollers has a specific resistance value of 0.1 to 1 on the surface of an insulating roller base material.
It has a conductive elastomer layer of 00 Ωcm, and heating of the roller is performed by energizing the elastomer layer. As described above, in the present invention, a conductive elastomer having a specific resistance value of 0.1 to 100 Ωcm is used as the resistance heating element from the viewpoints of workability, cost, adhesion to the pressure roller, and the like. Hereinafter, the fixing method and the fixing device of the present invention will be described in detail with reference to the drawings.

In the fixing device of the present invention, at least one roller may have a conductive elastomer layer on the surface of a cylindrical insulating roller base material. For example, as shown in FIG. The heating roller 1 having an elastomer layer may be used and the pressure roller 2 may be used on the other side. In this apparatus, the heating roller 1 is composed of a cylindrical insulating roller base material 1a which also serves as a rotating shaft, a conductive elastomer layer 1b provided around the insulating roller base material 1a, and a release layer 1c. The pressure roller 2 is composed of a rotating shaft 2a and an elastic layer 2b provided around the rotating shaft 2a.

In the fixing method of the present invention using this apparatus, the conductive elastomer layer 1b is heated in advance by energization, and the recording medium 3 having the toner image formed by the toner 4 is rotated in contact with each other. It is inserted between the contact surfaces of the rollers to fix the toner image under heat and pressure.
Hereinafter, each component of the fixing device of the present invention will be described.

In the present invention, at least one of the rollers has an electrically conductive elastomer layer on the surface of an insulating roller base material. As the elastomer constituting the electrically conductive layer in the present invention, tetrafluoroethylene propylene is used. -Based, vinylidene fluoride-based, fluorosilicone-based and other fluorine-based or silicone-based heat-resistant elastomers, depending on conditions, acrylic-based, nitrile-based,
General-purpose elastomers such as epichlorohydrin-based and ethylene propylene / non-conjugated diene terpolymer (EPDM), neoprene-based, butadiene-based or isoprene-based elastomers can also be used. As the conductive elastomer in the present invention, one formed by dispersing a conductive material such as carbon black, conductive inorganic powder or conductive potassium titanate whiskers in the above elastomer is used. Further, an organic polymer such as polypyrrole, polythiophene, polyparaphenylene, or polyaniline, or a charge transfer complex such as anthracene and tetracyanoquinoline or pyrene and tetracyanoethylene may be dispersed in the elastomer to form a conductive layer.

The conductive elastomer formed is JIS
The standard rubber hardness A scale is preferably 50 to 90 °, and the specific resistance value is usually 0.1 to 100 Ωcm, preferably 0.1.
It is 5 to 50 Ωcm. If the specific resistance value is higher than 100 Ωcm, it will take too long for the temperature of the elastomer layer to reach the set temperature unless a high voltage is applied, and the temperature of the elastomer layer will not rise sufficiently and There is a risk that it will not happen. Also, the specific resistance value is 0.1Ω
If it is lower than 10 cm, the temperature rise rate is too fast, which makes it difficult to control the temperature, and the temperature becomes high, which may damage the fixing device.

The thickness of the conductive elastomer layer is 3 m.
It is preferably m or less, and more preferably 0.2 to 2 mm. When the thickness is more than 3 mm, the heat capacity of the elastomer layer increases, and the rise time is not shortened, which is not preferable. The maximum heat generation temperature generated in the conductive elastomer layer used in the present invention is usually preferably 150 ° C. or lower so that the fixing device and the peripheral heat-resistant members are unnecessary and inexpensive materials can be used. In such a conductive elastomer layer, Joule heat is generated due to the specific resistance when electricity is applied, and this heat generation immediately raises the surface temperature and acts as a heating roller. As the energizing means, a conductive brush such as a carbon brush or the like may be brought into contact with both ends of the heating roller to apply it. Further, in order to improve the application effect, conductive paint may be applied to both end surfaces of the heating roller. As the conductive paint, a generally known one can be used.

In the present invention, in order to prevent the toner from sticking to the heating roller on the outer surface of the conductive elastomer layer,
Silicone oil may be applied, or a release layer 1c may be provided as shown in FIG. For the release layer, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon, Teflon, silicone type, P
FA or the like is used. Such a release layer may be coated on the outer surface of the conductive elastomer layer or may be formed by inserting a roller into a tube of the material. The thickness of the release layer is usually 10 to 200 μm, preferably 30 to 100 μm. If the thickness is less than 10 μm, the release layer may be peeled off due to uneven thickness of the release layer.
If it is larger than 00 μm, the heat conduction is lowered and the rise of the surface temperature of the heating roller is hindered, which is not preferable.

As the columnar insulating roller base material used as the carrier of the conductive elastomer layer, it is desirable to use heat resistant resin or insulating ceramics. Further, it is desirable that the specific resistance value is 10 ¹² Ωcm or more. If it is less than 10 ¹² Ωcm, the insulating property is insufficient and a current also flows through the roller base material, so the temperature of the elastomer layer does not rise sufficiently.

The heat-resistant resin used is polyamide, polyamideimide, polyacetal, polycarbonate, modified PPO, polyethylene terephthalate, polybutylene terephthalate, polyarylate, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, aromatic. Polyester, polyphenylene sulfide, fluoropolymer, ABS resin,
AS resin, AAS resin, AES resin, ACS resin, methylpentene polymer, ultra high molecular weight polyethylene, polypropylene, phenol resin, diallyl phthalate resin,
Unsaturated polyester resin, epoxy resin, polyimide,
Examples thereof include polyurethane, cyclic polyolefin, and liquid crystal polymer. These resins may be a single resin, or two or more kinds of the above resins may be mixed and used. Further, a filler such as glass fiber may be added and used.

Materials for the insulating ceramics include alumina, magnesia, beryllia, zirconia, silica, forsterite, wollastenite, zircon, mullite,
Metal oxides such as cordierite, spodumene, aluminum titanate, spinel, barium titanate, etc., or silicon nitride, sialon, aluminum nitride, titanium nitride, silicon carbide, boron carbide, titanium carbide, tungsten carbide, lanthanum boride, boro. A metal non-oxide system such as titanium oxide or zirconium boride can be used. When these are used as a roller base material, one or two of the above materials are used.
Any kind of structure, that is, a sintered body, glass, or crystallized glass can be used as a form thereof by using at least one kind.

In the present invention, the insulating roller base material made of the above-mentioned material has a columnar shape in order to make the diameter small, but compared with a cylindrical roller base material having the same outer diameter. A significant improvement in strength can be seen. That is, comparing the bending strengths of the two, for example, when the thickness of the cylinder is ⅕ of the radius, the cylindrical one has 1.1 to 1.2 times the strength,
When the thickness of the cylinder is 1/10 of the radius, the columnar one has a strength of 1.6 to 1.8 times. Further, the cylindrical insulating roller base material is different from the cylindrical one in that the end portion can be directly processed to form a roller shaft, which simplifies the structure.
The cost can be reduced. On the other hand, the cylindrical roller base material has the advantage that the total volume of the material is small and the thermal efficiency is good. However, in the case of the cylindrical roller base material of the present invention, the total volume is large because it is a cylinder, but the small diameter This problem is solved at the time of conversion, and can also be solved by selecting a material in consideration of thermal conductivity.
The outer diameter of the cylindrical roller base material in the present invention is usually 20 mm or less, preferably 6 to 16 mm.

Of the pair of rollers that rotate in contact with each other,
As the other roller that forms a pair when one has a conductive elastomer layer, a commonly known roller is used without particular limitation. For example, a pressure roller having an elastic body or a rigid body on its surface is used. be able to.

The means for driving the heating roller and the pressure roller are not particularly limited, and any commonly known means can be used. This causes both rollers to rotate in contact with each other at a constant peripheral speed. At this time, the peripheral speed of the roller is not particularly limited and is appropriately selected. The nip width during fixing is usually 1 to 5 mm, preferably 2 to 4 m.
m, and the linear pressure is usually 0.01 to 4 kg / cm, preferably 0.1 to 3 kg / cm.

According to the fixing method of the present invention as described above,
By using a heating roller having a conductive elastomer layer on the surface of a cylindrical insulating roller base material, it is possible to downsize the device by reducing the diameter and weight of the roller. Further, since this method has high thermal efficiency, it consumes less power and at the same time can shorten the warm-up time (standby time). Furthermore,
If a cylindrical insulating roller base material having a smaller thermal conductivity is used, the thermal efficiency can be further increased and the above characteristics can be further improved.

[0025]

The present invention will be described in more detail with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

Example 1 The fixing part of a commercially available copying machine was modified into a fixing device according to the device shown in FIG. 1 to carry out the fixing method of the present invention. That is,
1 is a heating roller, the heating roller outer diameter D1 is about 12 m
m. The cylindrical insulating roller substrate 1a has an outer diameter of 10 m
mφ cylindrical polyphenylene sulfide (PPS)
It is made of resin (specific resistance value: 10 ¹⁵ Ωcm). The end portion of this insulating roller base material is processed to serve as a roller shaft. Reference numeral 1b is a conductive elastomer layer made of a conductive silicone rubber having a thickness of 1 mm and having a JIS rubber hardness A.
The scale is 70 °, and the specific resistance value is 2 Ωcm. 1c
Is a release layer and is composed of an insulating silicone resin layer having a thickness of 50 μm. A pressure roller 2 is composed of a rotating shaft 2a and an elastic layer 2b formed on the surface thereof. The rotating shaft 2a is 8
φSUS steel material, elastic layer 2b is 2 mm thick JIS
The rubber hardness is made of silicone rubber having an A scale of 40 °. As test conditions, an AC voltage of 10 is applied across the heating roller.
A fixing test was conducted by applying 0 V, setting the roller surface temperature to 100 ° C., and using the following toner as the toner, and adjusting the fixing speed to 20 mm / sec by this device.

The toner used in this embodiment is manufactured as follows. That is, styrene acrylic 10
0 parts by weight, carbon black (Cabot, Mogul L) 10 parts by weight, charge control agent (Orient Chemical Co.,
3 parts by weight of Bontron N-07) and 3 parts by weight of polypropylene wax (manufactured by Mitsubishi Kasei Kogyo Co., Ltd., Viscole 660P) are mixed, melt-kneaded, cooled, coarsely pulverized by a hammer mill, further finely pulverized by a jet mill, and air classification. The toner (average particle size 10 μm) obtained by
0.4 parts by weight of hydrophobic silica fine powder (Aerosil R-972, manufactured by Aerosil Co., Ltd.) was mixed with parts by weight and used in this example. Fix at 3000 at room temperature (20 ℃)
The sheets were continuously copied, but the fixing was good, and no defect due to the fixing device was found on the image. Further, the waiting time for the roller surface temperature to rise from room temperature to 100 ° C. was as short as 15 seconds.

Example 2 The same fixing device was constructed as in Example 1 except that the roller base material of the heating roller was replaced with a cylindrical polyether ether ketone (PEEK) resin (specific resistance value: 10 ¹⁵ Ωcm). . As a result, the fixability was similarly good, and no defect due to the fixing device was found on the image. The waiting time was as short as 15 seconds.

Example 3 The same fixing device as in Example 1 was constructed except that the thickness of the conductive elastomer layer of the heating roller was changed to 2 mm. As a result, there was no temperature unevenness and the fixability was similarly good, and no defect due to the fixing device was found on the image.

Comparative Example 1 In Example 1, the roller base material is a roller having an outer diameter of 8 mmφ SUS (stainless steel) material and an insulating silicone rubber layer having a thickness of 1 mm provided thereon as an insulating layer. The fixing method of the present invention was performed in the same manner as in Example 1 except that the base material was changed. As a result, the fixability was as good as in Example 1, and no defect due to the fixing device was found on the image, but the standby time was slightly longer, 60 seconds.

Comparative Example 2 The same fixing device as in Example 1 was constructed except that the resistance value of the conductive elastomer of the heating roller was changed to 2000 Ωcm. As a result, the temperature of the roller surface did not rise by 70 ° C. or more, and sufficient fixability was not obtained.

Comparative Example 3 A similar fixing device was constructed by using a cylindrical insulating roller base material (thickness 1 mm) having the same outer diameter and material as in Example 1.
As a result, the bending strength of the roller base material decreased, the linear pressure decreased in the central portion of the roller, and the fixing strength decreased in the central portion of the roller.

[0033]

INDUSTRIAL APPLICABILITY The fixing method and the fixing device of the present invention have low power consumption, the fixing device can be downsized by reducing the diameter of the roller, and the warm-up time (standby time) can be shortened. is there.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Heating Roller 1a Insulating Roller Base Material 1b Conductive Elastomer Layer 1c Release Layer 2 Pressure Roller 2a Rotating Shaft 2b Elastic Layer 3 Recording Medium 4 Toner

Claims (6)

[Claims] 1. A fixing method in which a toner image on a recording medium is heated and pressure-fixed between the contact surfaces of a pair of rollers that rotate in contact with each other. At least one of the rollers is a cylindrical insulating roller base material. Specific resistance value is 0.1-10 on the surface
Having a conductive elastomer layer of 0 Ωcm,
A fixing method characterized in that heating of the roller is performed by energizing the elastomer layer. 2. The fixing method according to claim 1, wherein the cylindrical insulating roller base material has a specific resistance value of 10 ¹² Ωcm or more. 3. The conductive elastomer layer has a thickness of 3 mm.
The fixing method according to claim 1 or 2, which is as follows. 4. A fixing device comprising at least a pair of rollers that rotate in contact with each other, wherein at least one of the rollers has a columnar shape in a fixing device that heats and fixes a toner image on a recording medium between contact surfaces of the rollers. 2. A fixing device comprising a conductive elastomer layer having a specific resistance value of 0.1 to 100 Ωcm on the surface of the insulating roller base material and having an energizing means for energizing the elastomer layer. 5. The fixing device according to claim 4, wherein the cylindrical insulating roller base material has a specific resistance value of 10 ¹² Ωcm or more. 6. The conductive elastomer layer has a thickness of 3 mm.
The fixing device according to claim 4, wherein: