JPS58208774A - Fixation device of toner image - Google Patents

Abstract

PURPOSE:To improve an offset phenomenon preventing effect sharply by forming an elastic layer on the periphery of a core roll to consitute a fixation roll to be contacted with toner images out of fixation and press roll. CONSTITUTION:The fixation roll 1 is obtained by forming the elastic layer 12 on the periphery of the core roll 11. For said core roll 11, an ordinary and proper core roll such as a aluminum or satinless roll is used. Silicone rubber, flurorinated silicone rubber or flurorine rubber is especialy sutiable for the material of the elastic layer 12. In the invented fixation device, the offset phenomenon preventing effect can be sharply improved as compared to the ordiary method by using a mold releasing solution and a cleaning means.

Description

[Detailed description of the invention] The present invention relates to a toner image fixing device.

A fixing method in which a sheet-shaped recording medium on which a toner image is formed using powdered toner is conveyed under pressure between a fixing roller and a pressure roller, and the toner is fixed onto a recording medium such as fIJ Y paper is conventionally used. , is well known in connection with electrophotographic devices and the like. The fixing roller.

This is the roller that comes into contact with the toner image when fixing the toner image on the recording medium, and the pressure roller is the one that comes into contact with the toner image during the fixing.
Touch the back side of the recording medium.

The fixing of the toner image depends on the pressure applied to the toner image by a fixing and pressure cylinder roller, and in some cases, heat may be applied along with the pressure.

The former fixing method will be referred to as the pressure fixing method, and the latter will be referred to as the heat fixing method.

Now, one of the second problems with such a fixing method is the offset phenomenon. This offset phenomenon is
When forming a toner image, some or all of the toner adheres to the fixing roller, and as the fixing roller rotates once, it is again deposited in a fixed layer on the recording medium, and is described below. It occurs through a similar mechanism.

That is, when fixing the toner image onto the recording medium, a portion of the toner constituting the toner residue adheres to the surface of the fixing roller that comes into contact with the toner band. Some of the toner that has adhered in this way sticks to the surface of the fixing roller, or
The ingredients penetrate into the roller's curved area. Such fixed substances and penetrating substances accumulate as fixing is repeated and are polymerized by the pressure during fixing or by the action of pressure and heat.

It becomes a stronger adherent or combines with the material surrounding the fixing roller.

This layered material has the same components as the toner, so it naturally has a strong affinity for the toner. Therefore, when one toner image is fixed and removed, the toner that has been fixed and removed not only adheres to the recording medium but also tends to adhere to things stuck on the fixing roller. Therefore, when the amount of stuck matter accumulated on the fixing roller reaches a certain level, the toner iron that is fixed and removed acts like an adhesive on both the recording medium and the fixing roller, and ”C1 The above-mentioned offset phenomenon occurs.

The mechanism of occurrence of the offset phenomenon is as described above, and in order to prevent the occurrence of the offset phenomenon, it is necessary to prevent the accumulation of adhered substances on the fixing roller.

Conventionally, for this purpose, the circumferential surface of the fixing roller is made of a material to which toner does not easily adhere, and in order to further promote the difficulty in toner adhesion, a release liquid is supplied to the circumferential portion of the fixing roller. Alternatively, a cleaning means such as a blade is brought into pressure contact with the circumferential surface of the fixing roller to remove adhering toner.

However, the action of the release liquid is to penetrate between the toner adhering to the surface of the fixing roller and the circumferential surface, weakening the adhesion force between the circumferential surface and the toner, thereby preventing toner adhesion and accumulation. In order to prevent this, it is not always possible to completely prevent toner components from penetrating inside the circumferential surface of the fixing roller.
It is difficult to prevent the offset phenomenon when the polymer is tightly packed. Unfortunately, even when a cleaning member is used, the cleaning effect is not sufficient because the pressure is just enough to not cause scratches or wear on the roller circumferential surface.

Further, it is powerless to remove toner components that have penetrated into the circumferential surface of the fixing roller.

Therefore, the present invention has made it possible to remove the toner components that have penetrated into the R surface of the fixing roller.

The object of the present invention is to provide a new toner image fixing device.

1. Description of the invention below. The present invention is characterized by the following three points.

That is, the first is that the fixing roller is formed with an elastic layer on the circumferential surface of the core roller.

The second is the contact pressure between the fixing roller and the pressure roller σ]
Q: It was set at 8Kf/Cm or more.

Thirdly, the width t at the contact area between the fixing roller and the pressure roller and the minimum thickness m of the elastic layer of the fixing roller at the contact area satisfy the following condition: 0t□≧30 This is what I decided to do.

The present invention can be applied to either pressure fixing or heat fixing.

It was. It is possible to further improve the offset phenomenon prevention effect by using a releasing liquid IJ = method.
[It's my stomach.

Is the figure an example of a toner image fixing device according to the present invention? It is shown schematically for explanatory purposes. In the figure, code 1 is a fixing roller, code 2
denotes a pressure roller, symbol S denotes a recording medium, and symbol Ill denotes a toner group.

The fixing roller 1 is constructed by forming an elastic layer 12 on the circumferential surface of a core roller 11. As the cored roller 11, any conventionally known appropriate cored roller such as aluminum or stainless steel may be used. The elastic layer 12 is made of a material to which toner does not easily adhere, and has appropriate elasticity and hardness. As the material for the elastic layer 12,
Examples include elastic bodies such as rubber, HPDM, and foams thereof, and particularly suitable materials include silicone rubber, fluorinated silicone rubber, and solid rubber.

The pressure roller 2 is a metal roller made of copper, aluminum, stainless steel, etc., or a nonmetallic hard o-roller (
'J The circumferential surface is plated with chromium or nickel, or the circumferential surface of a metal or non-metallic hard roller is made of tetrafluoroethylene polymer.

Those with a coating of high hardness silicone resin, or
Volikunirensulfide, nylon.

, IIS resin or other plastic VCXf) may be used. In the illustrated example, the pressure roller 2 is a hard roller, but the pressure roller may also be an elastic roller.

As shown in the figure, the fixing roller 1 and the pressure roller 2 are in pressure contact with each other in the axial direction, and each rotates in the direction of the arrow, so that the toner 1 image T7 is formed and the recording medium S7 is conveyed under pressure in the direction of the arrow. At the same time, the toner f image 'l' is fixed on the recording medium S. Since fixing is performed using a heat fixing method, for example, the core roller 11 is made hollow and a heater is placed inside the core roller 11 to heat the fixing roller l from inside and apply pressure to the toner particles in the fixing section. and heat.

Here, the fixing section is a section where the fixing roller 1 and the pressure roller 2 are brought into pressure contact, and the nip width is t.

In this fixing section, the elastic layer 12 of the fixing roller I is compressively deformed due to its elasticity. It is expressed as the thickness of the elastic layer 12 at the position where such compressive deformation is maximum, that is, the minimum thickness of the elastic layer 12 in the fixing section, 5 m.

Note that the pressure roller 2 may rotate together with the fixing roller 1, or may be rotationally driven separately from the fixing roller 1. Fixing roller 100,000 and pressure roller 2
Of course, I don't mind if you let me get carried away.

Now, the gist of the present invention is to fix the elastic layer by a force of 1 m acting on the elastic layer of the fixing roller at the fixing section, that is, at the contact point between the fixing roller and the pressure roller. This means that the outer peripheral surface IH1 is gradually worn away. By cleaning in this way, it is possible to remove not only the toner attached to the circumferential surface of the fixing roller, but also the toner components that have permeated inside the circumferential surface of the fixing roller, which could not be achieved with conventional mold release liquids or cleaning methods. , it becomes possible to remove penetrating toner components, and the effect of preventing offset phenomenon can be improved.

In order to wear out the elastic layer of the fixing roller, a shearing force of 8 degrees or more must be applied to the elastic layer.

In an experiment conducted by the inventor.

1 (1 ->30 -), the circumferential surface of the fixing roller was moderately worn, and it was found that the object of the present invention could not be achieved.

The above shearing force is @ when there is no recording medium in the fixing section.
It acts between the pressure roller and the recording medium when a recording medium is present.

The temporary force between the recording medium and the fixing roller can considerably contribute to wear of the fixing roller, and if appropriate conditions are set within the range where the above conditions are satisfied, the recording medium can be , the fusing roller may be worn only when passing through the fusing section.

In this way, the amount of wear on the circumferential surface of the fixing roller becomes proportional to the contact time with the toner iron.

This is suitable for realizing the purpose of the present invention.

There was a concern that if the length of 2.1027 m became large, the toner particles on the recording medium would be disturbed, but within the scope of the experiment, contrary to expectations, the toner particles were not fixed due to the disturbance of the toner particles. There was no deterioration in the image quality of the surface image.

In order to perform the fixing properly, even in the case of the heat fixing method, the contact pressure of the fixing and pressure rollers must be 0.
-8Kf/cIrL2 is required.

Hereinafter, description will be given based on specific examples.

Example 1 Dimethylhydroxysilyl-terminated polydimethylsiloxane (activity 5000C8 at 25°C); 70 parts Trimethylsilyl-terminated polydimethylsiloxane (viscosity +v2ocs at 25°C); 30 parts.

Polyethyl silicate; 3 parts.

Dibutyltin dilaurate; o, s parts.

Charcoal 1'ga calcium; 45 parts,
iron oxide ;
30 parts, titanium oxide; 3
o part.

A silicone rubber vulcanizate having the composition was formed in a layer to a thickness of 1.5 mm on the circumferential surface of a stainless steel cored roller having a diameter of 38 mm. This n was used as a fixing roller.

On the other hand, a pressure roller was prepared by providing a layer of tetrafluoroethylene polymer with a thickness of 10 μm on the circumferential surface of a stainless steel cored roller having a diameter of somm.

Are these fixing rollers and pressure rollers? Contact pressure 2.0Kg
/cm'. At this time, the nip width t is 4.
5Il1m, the minimum thickness m of the fixing roller elastic layer at the contact part is 1.2mm, therefore 1017m = 3
It is 8.

The fixing method is the 11 heat fixing method. For this purpose, a heater is installed inside the fixing roller, and 2
The surface temperature of the valley rollers was set to 180 cc, and the circumferential speed of each roller was set to 60 crn/see.

Incorporate this I9 fixing device into an electrophotographic device.

Copying was carried out using a manuscript with a photoreceptor area ratio of 8 inches, and the electrostatic a group obtained on the photoreceptor was visualized with toner.

The resulting toner particles were transferred to transfer paper (B4 size) as a recording medium, and fixed by the fixing device described above.

Note that the toner contains unsaturated polyester resin; 100 parts;
A mixture of 20 parts of styrene (n-butyl methacrylate) resin and 45 parts of carbon black was used.

During repeated copying processes, the offset phenomenon could be prevented up to 32,000 (11) sheets without using a release liquid.

In addition, dimethyl noricone oil (25°
When C was supplied with an activity of 200CS), the offset phenomenon could be prevented up to 80,000 sheets. The copy image was of very good quality.

For comparison, the contact pressure of one roller is 9 Kg 7c
When I lowered it with m21, I got t-3・Qxm, m=1・4, and lQ17m=21. In order to make the time for passing through the fixing part the same as in the above example, we conducted an experiment similar to the above, setting the circumferential speed of both rollers to 40 cm/sec.
Even if a release liquid was used, an offset phenomenon occurred after 50,000 to 55,000 sheets were printed. When the offset phenomenon occurs,
The circumferential surface of the fixing roller was examined, but no wear was found on the circumferential surface. - 10,000, in the good example above.

As the number of fusing increases, the circumferential surface of the fusing roller decreases.

Mene Akira noticed that the pieces gradually lost their original luster and began to wear out.

<Example 2> Polydimethylnoroxane having an average of 0-006 vinyl groups per silicon atom (at 25QC, viscosity
l'+[50iJOC8) ;100
Department.

Fumed silica (surface area 20() m2/g, trimethylchlor/ran treatment); 3o parts, cerium oxide 1o・4E'tl
“s.

Iron oxide: 1 part 0 parts, benzoyl peroxide: 1.2 parts.

7J11 sulfur rubber of silicone rubber composition, diameter 38
It was formed as an elastic layer on a stainless steel core metal roller of m+i. The depth is 2 fights. This was used as a fixing roller.

On the circumferential surface of the stainless steel cored roller with a diameter of 50+aii,
A fluorinated graphite eutectoid nickel plating layer (fluorinated graphite volume 20%) was provided with an average thickness of 15 μm.

This was used as a pressure roller.

These pieces are pressed together with a contact pressure of 3・QKp/lx2.

2 at the contact part, t = 5・5mTR, m = 1・(l
mm, ioz/m-55.

The circumferential speed of each roller was 5QcTn/sec, styrene-(ethyl methacrylate) resin;
An experiment similar to that in Example 2 was conducted using a toner obtained by cross-grinding 15 parts of a carbon blank using a coarse pressure fixing method.

As a result, it was 20,500 (100,800 to 20,800) without mold release liquid.
The off-cent phenomenon can be prevented up to r1 sheet, implementation fU 1
80,500 (1=9
The offset phenomenon could be prevented for up to 10,000 copies. In this case too,
As in Example 1+lJl, no wear was observed on the circumferential surface of the fixing roller.

For comparison, let's reduce the contact pressure 'r 1-2 by 9/Sec i.

t=4.0mm, m=1-7mm, 10t/m=24
It became. When an experiment was conducted in the same manner as the comparative example in Example 1, an offset phenomenon occurred and the circumference of the fixing roller was There was very little surface wear.

<Example 3> Using a vulcanized product of Fluorine Comb (trade name: Tecnoflon LHF 1 day 2E Zeon Co., Ltd.), an elastic layer with a thickness of 3 mm was formed on the circumferential surface of a stainless steel core roller with a diameter of 38 III+. This was used as a fixing roller.

-10,000, methyltrimethoxysilane; 3000 parts N
-β(aminoethyl)-γ-aminopropyltrimethoxysolane; 450 parts γ-chloropropyltrimethoxy7 run; too triethoxysilane; 300 parts digityltine diacetate; Add 300 parts of monochloroacetic acid at 30 to 40°C, then add 400 parts of water at 30 to 40°C to make a partial hydrolyzate. Apply the solution to the circumferential surface of a stainless steel roller (50 fins in diameter). It was dried for 2 hours at a temperature of .degree. C. to form a high-hardness silicone resin film (thickness: 1-5 mm), and this roller was used as a pressure roller.

When both rollers were brought into contact with each other at a contact pressure of 0.8 Kf/cIn2, at the contact portion, 1=4-5tnti,
m=1.2r1M.

10t/m=38 and Natsuta.

The peripheral speed of each roller was 60 crIL/sec, unsaturated polyester resin; 100 parts, carbon black;
An experiment similar to that in Example 1 was carried out using a heat fixing method using 17 parts of toner that had been mixed and ground. NaP11
The surface temperature of each roller that was opened at a fixed time was set to 170 uC.

20,000 to 20,500 (10 pieces l) if no mold release liquid is used.
Preventing offset phenomenon @1 When the same mold release liquid as in Example 1 and 2 was used, offset phenomenon could be prevented up to 70,000 to 75,000 sheets. Wear on the circumferential surface of the fixing roller was clearly observed. There were no problems at all in terms of image quality.

Next, for comparison, the contact pressure is Q, 5 Kg 7cm2i
When lowered, m = 1.2mTR5
101/m=33. When an experiment was conducted in the same manner as in the comparative example in Example 1 and 2, it was found that 500
~1500 pieces, 35,000 yen even if you use mold release liquid 'Yl'll
~40,002 (10) There was an offset phenomenon of 2 with one sheet, and no wear was visually observed on the circumferential surface of the fixing roller.

As described above, with the fixing device of the present invention, it is possible to obtain the same off-sera h phenomenon prevention effect as the conventional fixing device, even without supplying a release liquid to the fixing roller or providing a cleaning means. By using a mold release liquid and a cleaning means in combination, it is possible to dramatically improve the offset phenomenon prevention effect compared to conventional methods.

[Brief explanation of drawings]

The figure is an explanatory 11llI side view of one embodiment of the present invention, in which only the parts necessary for explanation are omitted. 1... Fixing roller, 2... Pressure roller,
S...Deployment medium, 'V...Toner 1 image, 11
... Core metal roller, 12... Elastic body layer. t...Nip width, m...Minimum thickness of the elastic layer 12 in the fixing part

Claims (1)

[Claims] A toner image is formed using powder toner. A device for fixing the toner@ on the recording medium while conveying the sheet-like recording medium under pressure between a fixing roller and a pressure roller, the fixing roller and the pressure roller fixing the toner on the toner image. The fixing roller, which is a contacting roller, is configured by forming an elastic layer on the circumferential surface of a cored roller, and the contact pressure between the fixing roller and the pressure roller is 0.8 Kg/cIn2 or more. The nip width t at the contact portion of both rollers, and the nip width t at the contact portion. The minimum thickness m of the fixing roller elastic layer is. Toner 1 is characterized in that it satisfies the following condition: 0t □ 〉 = 30
Elephant fixation device.