JPH01231077A - Fixing device and recorder - Google Patents

Abstract

PURPOSE:To enable shortening thermal time constant, to improve peeling property and thermal efficiency, as well in the heat-fixing process at a toner processes by using a heating body constituting at least a high-strength nitrogen reacted coupled ceramic composite substance. CONSTITUTION:For a fixing means in various kinds of toner processes such as electrophotography, optical printer, electrostatic recording, magnetic recording, a ceramic material composed principally of a base material of a nitrogen reacted coupled ceramic composite substance such as an Si3N4 coupled SiC ceramic composite substance 1 is used as a basic constituting material. Moreover, when conductive particles are coupled with the Si3N4 as necessary the ceramic substance becomes conductive and, when this conductive ceramic substance is integrally sintered after it is applied to the surface of the above-mentioned structure body, an excellent conductive coated film 2 can be obtained, and thus, a strong coated film for fixing can be obtained. Therefore, the thermal time constant is shortened. Moreover, since the reactive conductor is directly formed on the Ni reacted ceramic, a mold releasing agent effect utilizing homogeneous heating and the adsorption and permeability characteristics of an unglazed substance is sufficiently exerted. Accordingly, excellent pictures and a fixing property having high thermal efficiency are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to nitrogen reaction bonded ceramics such as high-strength Si
3N+ bonded SiC was utilized. The present invention relates to fixing devices for electrophotographic and optical printers, electrostatic printers, magnetic printers, etc., and devices using the same, such as electrophotographic and optical printers, electrostatic printers, and magnetic printers.

[Conventional technology]

Conventional, electrophotographic, optical printer, electrostatic printer.

2. Description of the Related Art A toner fixing process that involves a toner development process in magnetic printers and the like usually employs a fixing method using a heating roll. The main types are those in which an aluminum drum is coated with silicone, Teflon, etc., and an indirect heating method is adopted from inside the aluminum drum using an instantaneous heating device using a halogen lamp, or [
``Direct heating ceramic heat roll for electrophotography'' Electrophotography Society 59th Research I, Bullion (1987) Proceedings p] 14
As proposed on page 118, a resistor is formed on ceramic by plasma spraying, a current is directly applied to the resistor to generate heat, and an insulating film is provided on the surface of the resistor to directly heat the drum.

[Problem to be solved by the invention]

Considering the above two conventional technologies in more detail,
The front sound is indirect heating, and the light from the halogen lamp leaks to the outside from the bearing part, which has a negative effect on the photoreceptor, so structural considerations are required, making the device complicated. has a large heat capacity,
It has the disadvantage that the heat generation rise time constant cannot be shortened.

In addition, the latter is also expected to improve the thermal time constant because it changes from indirect heating to direct heating, but the base material is a metal pipe and has a multi-layered structure including binding material, insulation material, and resistor. Tame compound 3 I [is.

The properties of the fixing drum are: firstly, rapid heating, that is, shortening the thermal time constant; secondly, uniform fixing properties and good releasability from the toner; and thirdly, , low heat loss and high thermal efficiency, and fourthly, it is necessary to avoid unnecessary radiation or adverse physical and chemical effects on the electrophotographic process. The situation is far from satisfactory in various processes including toner fixation processes, such as electrophotography and various toner processes.

The purpose of the present invention is to have a short thermal time constant, good releasability, high thermal efficiency, and various types of electrophotography, optical printer recording, electrostatic recording, etc., regarding the four properties necessary for fixing.
It is an object of the present invention to provide a new fixing device and an application device thereof that have durability at various process speeds without having any adverse physicochemical effects on various processes including 1-ner processes such as magnetic recording.

[Means to solve the problem]

In the fixing means in various toner processes such as electrophotography, optical printers, electrostatic recording, and magnetic recording, nitrogen/reactive bonded ceramics such as Si3N4 bonded SiC ceramic composites are used to satisfy the four basic properties of fixing. By using ceramics whose base material is the book structure, it is possible to make drums necessary for fixing, or complex shapes other than drums, and it has a bending strength of over 350 MPa, and it also has a high dimensional accuracy. A very good anchoring structure can be made. The dimensional change rate of this ceramic during sintering is 0.13% or less, and it is possible to create a fixing structure that cannot be created with conventional ceramic materials.

Also, if conductive particles are bonded with 353N4 as necessary,
If it becomes a conductive ceramic and is integrally sintered onto the surface of the structure, it becomes a good conductive coating and a strong fixing coating can be obtained. Also, the coefficient of thermal expansion is 2,9 x 10-6/
Because it is as small as 'C, it can withstand rapid temperature rises and can significantly shorten the fixing start-up time constant.

In addition, regarding thermal efficiency, the thermal diffusion coefficient of the base structure is 9.77.
X 10-8/'C, which is much smaller than metals, prevents heat from diffusing to unnecessary parts, allowing efficient heating of the surface conductive layer. Since this sintered body is made in an N2 (nitrogen) atmosphere, an appropriate amount of molding resin is added to it, so even when a conductive treatment film is formed, it is close to a "sintered" state and has fine porosity and It maintains excellent impregnating properties.Therefore, it can be used as a releasing agent for fixing, such as oil-based substances, silicone-based substances,
Compatibility with fluoride substances etc. can be ensured.

In addition, the sintered nitrogen-reactive ceramic Sj 3N4 bonded SiC is extremely chemically stable, has excellent heat resistance and oxidation resistance, has little deterioration, does not emit harmful substances in the toner process, and has special properties. Since it does not have a high temperature part, it does not generate excess radiant flux.

As mentioned above, the fixing device using this material.

It is possible to provide a fixed structure that is close to the ideal conventionally considered.

Further, the nitrogen reaction bonded ceramic composite of the present invention will be described in detail.

This ceramic composite is made by integrally molding and sintering ceramics with different electrical resistivities, and is made of metal Si or ferro S.
5iaN4,5i2NzO produced from j.

5iOz bound by at least one particle or whisker.

In this ceramic composite, adjacent ceramics have different electrical resistivities, and the conductive compound for changing the electrical resistivity is a non-oxide conductive material, including LHa, IVa, and Va.
, ■al■ group nitrides and carbides.

Borides, silicides, especially TiN, TiC.

TiB2. TiSi2. ZrN, ZrC, ZrB2゜Z
r5iz, HfN, l-1fC, TaN, TaC.

TaB2. Ta S iz, MO2N, MO2C, M
OB.

Cr2N, Cr3C2, CrB, Cr5iz, NbN.

NbC, Nb5iz, VN, VC, WC, and WSiz are mainly used.

In particular, TiN, TiC9ZrN, ZrC.

Cr 2N and Cr 3C2 have excellent oxidation resistance and are suitable.

Further, the content of conductive particles in the sintered body to reduce the electrical resistivity is preferably 80 oQ% or less.

This is because when the content exceeds 80 voQ%, the properties such as mechanical strength, thermal shock resistance, and oxidation resistance of the ceramic deteriorate.

Furthermore, the electrical resistivity of the sintered body can be arbitrarily changed by changing the conductive particles in the sintered body from 5 to 80vo (1%). By containing it inside.

It can be produced arbitrarily within the range of 1014 Ω■ to 10 −5 Ω luster.

This ceramic composite is S i 3N4. produced from metallic Si or ferro-Si. S i 2N20. S
It is made by combining conductive particles or insulating particles with at least one type of i02, and the volume change rate during sintering is small and there is no deformation. In addition, 5iaN4.2 made of metal Si or ferro-Si is used between two layers having different electrical resistivities. S1
It is bonded with 2Nz○ or SiO2, and the bonding interface has excellent heat resistance and heat attack resistance like the base material.

It is preferable that the sintered body has a porosity of 5 to 40%. When the porosity exceeds 40%, the mechanical strength decreases and it is difficult to reduce the resistivity. Furthermore, if the porosity is less than 5%, the resistance to ventilation of nitriding gas, oxidizing gas, etc. due to reaction of metal Si or ferro-Si increases, making it difficult to obtain a good sintered body. This is because a conductive compound or an insulating compound and metal Si or ferro-Si react with a nitriding gas or an oxidizing gas to form 5 iaN+.

In order to convert the gas into the SiO2 or 5izNz○ phase and to bond the Mi compound or the conductive compound, vent holes are required for the gas to pass through the molded body.

By allowing 5 to 40% of pores to exist in the sintered body, stress caused by differences in thermal expansion coefficients of the ceramic layers having different electrical resistivities is alleviated, thereby preventing cracks in the sintered body.

In addition, the average particle size of gold JiSi or ferro-Si was 5 μm.
The following is preferable. This is because the average particle size is 5 μm.
If it is larger than , the nitriding time becomes longer and the residual Si
This is because it comes to exist.

Examples of binders for molding the above composites include thermoplastic resins such as polyvinyl butyral and polyethylene;
Organic S such as silicon imide compounds and polysilane compounds
i high molecular compounds etc. are used, and the blending amount is 2 to 20
It is preferable to add it in parts by weight so that the relative density of the molded product is 60% or more.

In addition, the compact is heated to at least 1350°C in a nitriding, oxidizing, or oxynitriding gas atmosphere such as nitrogen, ammonia, or oxygen (add gases such as hydrogen, argon, helium, or carbon oxide as necessary). .

As the metal Si, ferro-Si, insulating compound, and conductive compound, commercially available ones can be used as they are. Note that it is more preferable to use rounded particles obtained by crushing the particles using a mill or the like.

When whiskers are mixed and dispersed in the raw material in advance, not all of the whiskers are combined with the particles, and lumpy whiskers or individual whiskers remain between the particles of the sintered body. On the other hand, in the present composite, the voids between the particles are bonded together by a large number of needle-like whiskers generated from the particles in the molded body, which intersect almost straight, which greatly contributes to the thermal shock resistance and high strength.

According to this ceramic, the gaps between the particles and/or whiskers of the insulating compound and the conductive compound are three-dimensionally bonded by a large number of whiskers generated from the Si particles in the molded body, and the whiskers that are not in a bonded state are Since there is almost no carbon, a sintered body with excellent toughness and high-temperature strength can be obtained.

The average particle size of the particles of the insulating compound and the conductive compound is preferably 100 μm or less.

This is because when the thickness exceeds 100 μm, the strength of the sintered body decreases. Also, when using ready-made whiskers of insulating and conductive compounds, the average aspect ratio is 2 to 50.
．． The length is preferably 0.2 to 100 μm. If the aspect ratio is less than 2 and the length is less than 0.2 μm, there will be no effect as a whisker, and if the aspect ratio is more than 50 and the length is more than 100 μm, it will be difficult to mix the raw materials and the dispersibility will be poor.

This is because whiskers account for 1 to 70 voQ% (preferably 10 to 30 voQ%) of the generated particles and whiskers in the sintered body.
This is because the effect cannot be obtained with the composite ceramics containing voΩ%) outside the above range.

The molding method is selected depending on the shape and required characteristics, such as injection molding, cast molding, rubber press molding, extrusion molding, or two-mold molding.

After removing molding aids and the like from this molded body, whisker generation heat treatment is performed. The particles or whiskers produced are 5i
aN+ is most preferred.

In this composite ceramic, among the conductive compounds, silicides and borides react with nitrogen in nitriding gas, so if the sintering time is inappropriate, cracks tend to occur in the sintered body, so nitrides are used.

Most preferably, carbides are used.

The whiskers generated in this composite ceramic are Si
In addition to whiskers generated from particles, 5iaN is used as a raw material.
+, whiskers such as SiC may be mixed. However, mixing too much will result in non-uniformity, which is not preferable. Further, whiskers may be used as an insulating compound or a conductive compound.

Furthermore, it is also possible to re-sinter the sintered body in order to reduce the porosity of the sintered body to less than 5%. For resintering, secondary sintering can be performed using a hora+he press, hot isostatic press, or normal pressure using a sintering aid. As a result, whiskers exist three-dimensionally in the sintered body, so a highly heat-resistant ceramic composite can be obtained. However, cracks may occur unless the difference in thermal expansion coefficients is made as small as possible.

[Effect]

According to the present invention V nitrogen reactive ceramics 5iaN4 bonded Si
In fixing devices using C sintered bodies and their applications such as electrophotographic devices, optical printer devices, electrostatic writing devices, and magnetic printer devices, it is possible to uniformly shorten and improve the toner process start-up time. It is possible to provide an ideal fixing device with improved peelability, improved thermal efficiency, and prevention of harmful radiation, and at the same time, in applied devices, it is possible to reduce power consumption, improve recorded image quality, and stabilize it.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, 1 is a nitrogen reaction bonded ceramic S i
3N4 bonded SjC ceramic drum, 2 is Si3N4 bonded conductive ceramic, and 3 is a power supply slip ring for power supply.

This drum is constructed such that both ends are made smaller than the outer diameter than the central part, a conductive ceramic 2 is attached to these parts, and a voltage is applied from the outside by a slip ring 3.

FIG. 2 shows another embodiment, in which each configuration of 1 and 2.3 is
It is the same as the figure, but the inner surface of the drum is filled with 4 permeable mold release oil. In this action, the release agent that has permeated the drum passes through the nitrogen-reactive ceramic and seeps out to the surface, exhibiting release properties against fixed toner adhesion, and does not leave unnecessary adhesion on the surface of the fixing tram when toner is fixed.

Generally speaking, toner adhesion to the fixing drum that occurs during toner fixation is caused by two problems: cold offset, which occurs when the fixing temperature is too low, and high temperature offset, which occurs when the temperature is high. - From the viewpoint of fixing the toner, it is considered to be a good toner from a 1 to toner side.

On the other hand, when viewed from the fixing roll side, a fixing drum with good release properties has the effect of expanding this permissible temperature range, and if the permeability of the drum according to the present invention is utilized, this property can be greatly improved.

On the other hand, this permeability not only permeates from the inner surface of the fixing drum, but also works well when applying the release agent to the fixing drum, and has an effect comparable to the above-mentioned inner surface shape.

In yet another application, if the fixing drum is sufficiently impregnated with a release agent in the microporous "sintered" state and used as a heat fixing roll in the same way as a normal impregnated bearing, the external, Alternatively, fixing without causing toner offset can be continued without new impregnation from the inside.

FIG. 3 is an example in which a fixing drum having a drum-shaped fixing structure according to the present invention is applied to an optical printer including a toner process.

1 is a photosensitive drum, and in the case of a normal optical printer, selenium, selenite, organic photoconductor (OPC), etc. are used.

A charger No. 2 performs positive charging at No. 3, an electrostatic image is formed using an LED head No. 4, and a developed toner image No. 7 is obtained on the photoreceptor by a developing device No. 5 using a one-toner No. 6. . Recording paper is supplied from a paper cassette No. 8 by a paper feed roll No. 9, and a transfer image is obtained on a recording paper 14 by a transfer unit 11 using a paper guide 10. 12 is thermally fixed by the fixing roll shown in FIG. 1 or 2 and the pressure roll 13.
5 fixed toner is obtained. After fixing the toner, the recording paper 14 enters the stacker 16 to complete one recording process. These 12 fixing rolls have good characteristics for the offset roller 1, and since they do not emit unnecessary radiation, they can be assembled into a relatively compact device, and have good thermal efficiency, allowing the total power of the device to be reduced.

〔Effect of the invention〕

According to the present invention, the thermal time constant is shortened, and since the reaction conductor is formed directly on the Ni reaction ceramic, uniform heat generation is achieved, and the mold release effect using the adsorption and permeation characteristics of burning is improved. It is possible to obtain good images in minutes, and to obtain fixing properties with high thermal efficiency. Since there is almost no unnecessary radiation or physico-chemical action, the restrictions when integrating into a device can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a fixing drum showing an embodiment of the present invention, Fig. 2 is a diagram showing a fixing drum further filled with a release agent inside the drum, and Fig. 3 is an example in which the same is applied to an optical printer. FIG. 1...5iaNn bonded SiC ceramic drum, 2
... 5iaNi bonded conductive ceramics, 3... Power supply slip ring, 4... Filled mold release liquid.

Claims (1)

[Scope of Claims] 1. A heat fixing device characterized in that a heating element having at least a high-strength nitrogen/reactively bonded ceramic composite is used in a heat fixing step in a toner process such as electrophotography. 2. In item 1, Si_3N is used as a ceramic composite.
A heat fixing device containing _4 as a component. 3. The fixing device according to item 1, wherein the heat fixing device has a drum-like shape. 4. A fixing device characterized by applying, adsorbing, adhering, welding, impregnating, etc. a liquid or solid releasable material that improves the releasability of the developer near the drum surface as described in item 2. 5. The fixing device according to item 1, wherein the surface of the heating element is an electrically insulating layer. 6. Utilizing the open pores of the nitrogen reaction bonded ceramic composite,
A fixing device characterized in that a liquid toner release agent is supplied from the inner surface of the drum, or is coated or impregnated in advance. 7. In item 6, the nitrogen reaction bonded ceramic is Si_3
A fixing device made of N_4 bonded SiC. 8. A recording device including a toner process using a toner fixing device including the fixing device of Items 1 to 6.