JPH03288879A - Fixing device - Google Patents

Abstract

PURPOSE:To make releasing property excellent and to prevent an adverse effect from being given to an image by constituting the surface layer of a member being in contact with a developer image of a fluororesin film or tube. CONSTITUTION:On the core metal 6 of a fixing roller 1 being as the member in contact with the developer image among fixing, means, the uppermost layer of the PFA tube 8 obtained by adding adding a substance, which positively electrostatically charges iron powder, is formed through a primer layer 7 as adhesive agent. Due to that, the surface layer 8 is restrained to be strongly electrostatically charged. Therefore, strong electrostatic resileincy is not generated between the surface layer 8 and the developer image on a recording material and irregularity does not occur to the image. Besides, since the surface layer 8 is formed of the film or the tube made of the fluororesin, high wear resistance and high durability are attained. Thus, the releasing property is made excellent and the irregularity in the image is prevented from occurring easily, stably and under the state of actual operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a fixing device in an image forming apparatus such as an electrophotographic copying machine.

[Prior Art] Conventionally, various fixing methods have been proposed and implemented in image forming apparatuses such as in-shell electrophotographic copying machines, and currently, the heat fixing method is the mainstream.

Among these, a heat roll fixing method using a pair of rollers is being competitively adopted due to its high thermal efficiency. The basic configuration is shown in FIG. 7, taking as an example a case where a roller having a heat source is used on the image forming side.

In No. 81A, l is a fixing roller, and has a halogen heater 2 therein as a heat source. The constant It roller 1 is paired with a pressure roller 4 whose surface layer is made of an elastic material 3 such as rubber, and has an aperture (hereinafter referred to as a nip) at a suitable point 1, and is connected to a driving means (Fig. (not shown) causes the receiver to rotate when driven by the main body. The unfixed image is fixed on the recording material such as paper by heat and JE force when the recording material passes between the pair of rollers. ! jt working, fixing roller l
The surface of is maintained at a substantially constant temperature by a thermistor 5.

The fixing roller in a fixing device such as LO) generally contains a substance that prevents the adhesion of developer [1, fluorine m7J)]
Conventionally, the manufacturing method for such rollers has been to first use a fluororesin powder coating or dispersion coating and then bake it. It was considered a method. Furthermore, as a second method, a method has been proposed in which a heat-shrinkable fluororesin tube is heat-sealed to a cylindrical core made of metal or the like, as described in JP-A-59-198118. There is.

[Problems to be Solved by the Invention] However, the first and second conventional examples described above have the following problems.

First, in the first manufacturing method, the coating efficiency within the film was low, and it tended to be expensive. In addition, when silicone oil is supplied to the roller as a lubricant or mold release agent, the intrusion oil that has entered between the paint particles or the fixing heat (15
(0 to 200°C), there were problems such as swelling and blistering on the film. Furthermore, since pinholes are formed in the resin layer formed by this first manufacturing method, even if additives are mixed in to change the characteristics of the resin layer, the characteristics will not be uniform and the effect will not be stable. There was also the problem of not being able to obtain the required amount.

On the other hand, in the second manufacturing method, the fluororesin tube method,
If the fluororesin itself is extremely negatively charged (surface potential is approximately -2.5 kv to -3 kv or more), especially if a negatively charged developer is used in the fixing section,
A large electrostatic repulsive force is generated between the fluororesin and the developer,
There is a problem in that the developer on the recording material is blown away, resulting in large disturbances (splatter, crusting, etc.) on the image.

The present invention solves the above problems, has good mold releasability, and
It is an object of the present invention to provide a fixing device having a fixing roller or a pressure roller that does not adversely affect images.

[Means for Solving the Problems] According to the present invention, the above objective is: a fixing device equipped with a means for fixing a negatively charged developer image formed on a recording material onto the recording material. In the above means, the member in contact with the recording material or the developer image is 1rL, and the surface layer of the member is formed of a fluororesin film or tube to which a substance having a property of statically charging iron powder is added. This is achieved by being present.

[Function 1] According to the present invention, the surface layer of the member of the means for fixing the negatively charged developer image on the recording material, which is in contact with the L recording material or the developer image, contains iron powder. A substance that has the property of being positively charged is added to prevent the L surface layer from becoming strongly negatively charged. Therefore, no large electrostatic repulsive force is generated between the surface layer and the developer image on the recording material.
Does not disturb the image.

In addition, the L-shaped elbow is made of fluororesin film or tube, achieving high mffJf; and durability.

[Examples] The first and fourth embodiments herein are shown in the attached drawings.
This will be explained using the mountain or fJS7 diagram and FIG. 9.

First Embodiment First, a first embodiment of the present invention will be described using FIGS. 1 to 31A, and then compared with a conventional example using FIG. 9.

The apparatus of this embodiment fixes a negatively charged developer image formed on a recording material onto the recording material by using a fixing roller and a pair of rollers as a fixing stage. There is.

In FIG. 1, l is a fixed roller which is a member in contact with the developer image in the above-mentioned fixing means, and the iron powder is charged to iE through a primer tank 7 as an adhesive to a core metal 6. The maximum hr of tube 8 to 1] 1 with the added substance
It is formed at °C. ” - Below the fixing roller 1 is one of the above fixing means.

A pressure roller 4 as a member that contacts the recording material is disposed in pressure contact with the recording material.

Here, a positively charged substance is a blow-off method.
It refers to something that, when pressed, causes a positive tribo tun to the iron powder carrier. For example, there are some substances that can be halved.

■Nicrosin and their modified compounds■Tiron-containing compounds such as quaternary ammonium salts, pyridinium salts, amines, and amides, and nitrogen-containing heterocyclic compounds ■Organotin oxides and derivatives thereof■Triphenylmethane dyes and These lake pigments (combined with F-sulfur-containing monomer monopolymers or other hinyl-based monomers) (polymer 0 polyamide) are specifically the substances shown in Table 1.

(Leaving space below) Due to the structure of Table 1, the substances listed above must have a particle size of 20 μm or more, or a particle size of 1/2 or more of the H value of the film or tube to be molded with the fluororesin to which they are added. It is preferable that it is 1Y, and if it is more than 1-, it will be difficult to mix evenly during addition (-) or it will protrude to the surface layer, resulting in a 1Y characteristic of fluorine treatment resistance! ! In some cases, the L-type character may be impaired. Note that when these substances are added, they do not need to be added in solid form.

Next, the amount of acid added to these substances is preferably 0.1 parts by weight to 20 parts by weight based on 100 parts by weight of the fluororesin material used as the base material. This may be due to the additive line (if it is less than 1.1 part by weight, it will have little effect) (not only will it not be rubbed, but it will also be difficult to disperse uniformly, and if you try to add more than 20 parts by weight, the charge will be It has been confirmed through experiments that the mold releasability is reversed, or that the fluorine resin base material significantly impairs the old mold release properties.

On the other hand, the thickness of the molded fluororesin film or tube is preferably about 10 μm to 100 μm, and examples of the fluororesin material used as the base material include perfluoroalkoxide (PFA), polytetrafluoroethylene (
PTFE), hexafluoropropylene copolymer (F
EP), etc.

Next, a case in which an unfixed image formed with a negatively charged developer at a constant Fi811 is to be fixed using the fixing device t made of acidic acid will be described with reference to FIG. 2 and FIG. 91A.

It is generally known that positive charges and f1 GI attract each other, and that positive charges or negative charges repel each other. Conventionally, the surface layer of a heat fixing roller, etc.
Due to the characteristics of fluororesins such as A and P'rFF), they tended to become extremely negatively charged and stick.

Therefore, as shown in No. 9r71, when trying to fix the developer 9 with a single charge, an electrostatic repulsive force is created between the negatively charged resin layer 20 and the developer 9. Therefore, electrostatic offset is difficult to occur.

However, since the resin layer 20 is extremely negatively charged,
The repulsive force generated between the developer and the developer (arrow F in FIG. 9)
) overcomes various attractive forces and adsorption forces between the developer 9 and the recording material IO, and as a result, the unfixed image on the recording material is blown away. As a result, the phenomenon of causing large disturbances (scattering, roughness, etc.) on the image is noticeable, which is a particularly serious problem when a negatively charged developer is used in the fixing section.

In recent years, research and development have been actively conducted to reduce the volume resistance of the surface layer in order to weaken the repulsive force between the S + fat layer and developer in the surface layer formation of painting/baking types. There are disadvantages such as damage or electrostatic offset being more likely to occur, and in the case of types using fluororesin tubes, no countermeasures have been taken at present.

Therefore, as shown in FIG. 2, in this embodiment, the surface layer itself was made to have an appropriate potential. That is, the surface potential is -10[vl to -1[kvl, preferably -1
The surface layer was made of tutu-like or sheet-like PFA to which a positively charged substance was added to the iron powder so that it was charged to about 00 [V] to -300 [V]. As a result, by appropriately negatively charging the surface resin layer 8 with respect to the negatively charged developer 9, offset of the developer can be reliably prevented without impairing the characteristics of the fluororesin tube or film. However, it has been possible to prevent image distortion due to electrostatic repulsion. In addition, in the experiment, it was shown that good results were obtained when the surface potential of the resin scrap 8 was about to become smaller than -2 [kvl], but as mentioned above, it was particularly good and more preferable when the surface potential of the resin scrap 8 was less than -1 [kvlvl]. Ha-
10 (1 [vl ~ -: 100 [vJ] was charged. Also, as the voltage approached ±0 [vl from -10 [vJ], electrostatic offset was more likely to occur. At this time, the fixing unit An experiment was conducted on a recording material-L with an unfixed image formed using a developer having a negative charge, in which the triboelectric charge (charge amount per unit weight) was about -5 to -20 [pq/g1].

The so-called suction type Faraday gauge method was used to measure tribo. This suction type Faraday gauge method is generally the third
Using a device configured as shown in the figure, the suction port 11 is pressed against the recording material to suck the developer, and the filter 12 of the inner cylinder is
to collect. At this time, the inner cylinder is electrostatically shielded from the outside, and the amount of charge of the developer accumulated here is determined by the connected Faraday gauge 13, and 1'ILtJ of the sucked developer is determined by the weight of the filter. Based on the increase, the triboelectric charge (charge amount per unit weight) of the developer of the recording material 2 can be calculated.

Furthermore, in this experiment, tritutylpentylammonium-1-hydroxy-4-naphthosulfonate was used as an additive to resin waste 8), and the average particle size of this was 5[
μm] and (fF'Ftt M
4. t 1.84 [fiLq/gl -Q a-)
j:.

In addition, the amount of charge is 200/30 depending on the additive material or the iron powder carrier.
0 [mesl+] to 2 (wLZJ) and thoroughly mixed, and then measured using a Trow-off (TB-200 manufactured by Toshiba Chemical Corporation).

<Second Embodiment> Next, a second embodiment of the present invention will be described using FIGS. 4 and 5. Note that the same parts as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

This embodiment differs from the first embodiment in that the present invention is implemented on the side of the roller that does not come into direct contact with the unfixed image. A case where this fixing device is used to fix an unfixed image formed using a developer having a negative charge in a constant R portion will be described with reference to FIGS. 4 and 5.

In FIG. 4, an additional IE roller 4, which is paired with a fixing roller l having a built-in heat source 2 with an appropriate nip, is an elastic layer 3.
It is composed of a PFA tube in which a substance that charges iron powder to II- is added to the upper surface layer, the fat layer 8.
A static eliminating brush 14 for eliminating static electricity on the surface is brought into contact with the peripheral surface. The resin debris 8 is controlled and configured so that it becomes weakly negative (iF'if) due to contact and friction with the recording material 10. When the recording material 10 carrying an unfixed image enters the fixing device, the resin debris 8 is controlled and configured to have a weak negative value (iF'if) as shown in FIG. In the nip portion, charging occurs between the resin layer 8 on the surface of the pressure roller and the recording material 10, and a weak negative charge is generated on the resin debris 8.In addition, the recording material 10 is charged with a weak negative charge. Since a static charge is generated, the electrostatic attraction between the developer 9 and the recording material IO increases, and as a result, the developer 9 becomes more difficult to offset and at the same time becomes less likely to cause scattering or rustling. .

On the other hand, the resin layer 8 is weakly negatively charged due to the charging with the recording material.
After separating from the recording material, the charge is removed by the charge removal flange 14. This is to prevent frictional charges with the recording material from accumulating on the resin debris and generating a strong repulsive force with the developer. When the developer used in the first practical example was tested, it was found that the resin layer 8 containing nigrosine came into contact with the recording material J9! Good results were obtained with approximately -500 (vJ) between the stripping surface potential due to rubbing and the static elimination flange.Here, the average particle size of nigrosine was 5[d・＼・The amount of charge on the rear is 16.76 [#Lq/g
l (measurement was performed using the same method as in the first example)
.

<First example> Next, a third embodiment of the present invention will be described using FIG. 6.

Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment differs from the first embodiment in that a seamless fixing film is used as a member of the fixing means that comes into contact with the developer image. The fixing film 15 formed into the shape of a seamless belt is made of a PF^ film containing a substance that positively charges iron powder, and a fixing heating element 16 provided inside the film is connected to a pressurizing roller and a suitable material. It is abutted with a nip. The recording material IO carrying the unfixed image is fixed by heating and pressure at the nip portion.

As described above, conventional fixing devices using fixing films have had problems with image disturbances such as scattering and roughness, but with the use of the film according to the present invention,
In the first embodiment and Mr. P4, outstanding effects can be obtained.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described using FIG. 7.

This embodiment differs from the third embodiment in that it utilizes the rightmost fixing film. This embodiment also provides the same outstanding effects as the first embodiment.

Note that the present invention is not limited to heat fixing methods,
It can be applied to all fixing methods that directly contact unfixed images or recording materials.

In addition to the substances already mentioned as substances that charge I to iron powder, we have also conducted experiments and measurements on the substances shown in Table 2, and the results are the same as when the above-mentioned substances are added. It has been confirmed that the effects of
The same method as in the example was used).

Table 2 (blank below) [Effects of Origin 1] As explained below, according to the present invention, among the fixing means, the surface layer of the member in contact with the recording material or developer image is coated with iron powder. By forming a film with a fluororesin film or tinib to which a positively charged substance has been added, the charged state can be arbitrarily adjusted while maintaining the high wear resistance and durability characteristic of fluorocarbon resin. becomes possible, and
Unlike conventional painting methods, there are no pinholes, making it possible to maintain a stable electrical charge state. It is now possible to easily and stably prevent image disturbances such as scattering and roughness caused by electrostatic repulsion under actual operating conditions. Furthermore, unlike the case where a chemical is added to the release agent of a fixing device equipped with a release agent application mechanism, the present invention is extremely safe and is suitable for any M working situation (i.e., at the initial stage of operation, after 10,000 sheets have been used, etc.). The effect is not impaired at all even in the operating state of the main body, and there is no need to provide a special mechanism such as a release agent application mechanism.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a device according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the nip portion of the device shown in FIG. 1, and FIG.
The figure is a cross-sectional view showing the schematic configuration of a measuring device using the Faraday gauge method used in the measurement of the first embodiment, FIG. 4 is a cross-sectional view showing the schematic configuration of the device of the second embodiment of the present invention, and FIG. 4
Figure 6 is an enlarged cross-sectional view of the nip portion of the device, Figure 6 is a cross-sectional view showing a schematic configuration of a device according to a third embodiment of the present invention, and Figure 7 is a cross-sectional view showing a schematic configuration of a device according to a fourth embodiment of the present invention. , FIG. 8 is a sectional view showing a schematic configuration of a conventional fixing device. FIG. 9 is an enlarged sectional view of the nip portion of the device shown in FIG. 8.

Claims (1)

[Scope of Claims] A fixing device comprising means for fixing a negatively charged developer image formed on a recording material onto the recording material, wherein the means is in contact with the recording material or the developer image. A fixing device comprising a member, the surface layer of the member being formed of a fluororesin film or tube to which a substance having a property of positively charging iron powder is added.