JP2001317541A - Mold releasing agent coating roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold releasing agent coating roller capable of always feeding a proper amount of mold releasing agent and providing a long life by providing a surface layer with a sufficient adhesive strength without using a cylindrical film. SOLUTION: A felt layer 23 is wound on a base material 22 as a tubular ceramic member to form a mold releasing oil holding layer. An adhesive layer 24 formed of a mixed adhesive agent comprising silicon rubber and dimethyl silicon oil is coated on the surface layer 25 of a two-axis flattened PTFE sheet, and the sheet is wound on the felt layer 23 to form an oil feed roller 12. The adhesive layer 24 is formed so that both end parts 30 and 30 and lap part 31 thereof have such a composition and thickness as placing an emphasis on an adhesive strength, and that the other portions 32 have such a composition and thickness as placing an emphasis on the permeability of the mold releasing oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release agent applying roller for applying a release agent to a rotating body. More specifically,
The present invention relates to a release agent application roller that holds a release agent on an inner holding layer and applies the release agent to a rotating body via a surface layer. For example, it is suitable for use in supplying fixing oil to a fixing device of an image forming apparatus using toner.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using toner has a fixing device for fixing a toner image on a sheet to the sheet. Here, in order to prevent toner from adhering to the fixing roller of the fixing device, it is necessary to supply a release agent (also referred to as fixing oil) to the fixing roller. Particularly, in recent years, a rubber roller that does not excessively crush a toner image is often used as a fixing roller due to a demand for higher image quality. Since the rubber roller easily adheres to the toner, it is important that the release agent is reliably supplied. Of course, the supply of release agent must not be excessive. This leads to stickiness and contamination of each part.

[0003] As one example of a conventional release agent application roller that meets such demands, there is an oil application roll described in Japanese Patent No. 2888267. This oil application roll is generally provided on the outer peripheral surface of a cylindrical oil holding layer.
It is constituted by providing a surface layer of a porous fluororesin film. The heat-shrinkable cylindrical film is used as the porous fluororesin film. That is, the cylindrical porous fluororesin film is shrunk by heating and is brought into close contact with the oil retaining layer.

[0004]

However, the above-mentioned conventional release agent applying roller has the following problems. That is, the porous fluororesin film having a cylindrical shape used as a surface layer has a large diameter (30 mmφ) due to its production.
Above) is difficult to obtain. For this reason, the amount of the release agent that can be impregnated in the release agent application roller is limited, and only a short life product can be obtained. In addition, it is difficult to obtain a thin porous fluororesin film having a cylindrical shape. For this reason, the surface of the release agent application roller is hard, and the contact with the object becomes uneven. As a result, application unevenness of the release agent occurs, and as a result, toner adheres to the fixing roller. Further, the fact that the surface layer is thick also means that the moving speed of the release agent from the oil holding layer to the outside is slow.
For this reason, the supply of the release agent tends to be insufficient during continuous printing of a large number of sheets.

The present invention has been made to solve the above-mentioned problems of the conventional release agent applying roller. That is, the problem is to obtain sufficient surface adhesion without using a cylindrical film.
An object of the present invention is to provide a release agent applying roller which can always exhibit an appropriate supply amount of the release agent and has a long service life.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. A release agent applying roller according to the present invention, which applies a release agent to a rotating body, comprises a surface layer constituting a surface,
A holding layer that is located inside the surface layer and has a function of holding the release agent, and an adhesive layer that bonds the surface layer and the holding layer,
In the adhesive layer, portions having different release agent permeability are provided.

In this release agent applying roller, the surface layer is adhered to the holding layer by the adhesive layer. For this reason, even if the material of the surface layer is not cylindrical and flat, the adhesion to the holding layer is ensured. Here, it cannot be denied that the presence of the adhesive layer between the surface layer and the holding layer may be a factor that hinders the transfer of the release agent from the holding layer to the surface layer. Therefore, this problem is dealt with by providing the adhesive layer with a part having different release agent permeability. That is, in general, it can be said that the permeability of the release agent in the adhesive layer and the adhesive strength have an opposite relationship. Therefore, by providing a part that emphasizes the permeability of the release agent and a part that emphasizes the adhesive strength, both properties are compatible as a whole.

Therefore, in the release agent applying roller of the present invention, the release agent is silicone oil, and the adhesive layer contains silicone oil. It is desirable that the oil content be different. An adhesive layer containing silicone oil has different permeability and adhesive strength of silicone oil (release agent) depending on the content of silicone oil. That is, an adhesive layer having a low silicone oil content has a low permeability and a high adhesive strength. Conversely, an adhesive layer having a high silicone oil content has a high permeability and a low adhesive strength. Therefore, the content of the silicone oil may be increased in the adhesive layer where importance is placed on the permeability, and the content of the silicone oil may be decreased in the adhesive layer where importance is attached to the adhesive strength. In addition, as a means for providing a difference in the permeability of the release agent in the adhesive layer, in addition to the above, a difference in the thickness of the adhesive layer can be given.

For example, it is desirable to provide a portion at the end of the roller axis direction where the permeability of the release agent of the adhesive layer is different from other portions. Generally, the overall width of various rollers, such as a release agent application roller, is given a margin more than the maximum width of the printing paper. Therefore, in the region outside the maximum width of the print paper at the end in the roller axial direction, the applicability of the release agent does not matter much. Therefore, in this area, a portion may be provided in which the adhesive strength is more important than the permeability of the release agent. Then, the paper passing area on the inner side is set as a part where the permeability of the release agent is more important than the adhesive strength.

[0010] In the release agent applying roller of the present invention, it is desirable that the surface layer is composed of a sheet-like porous body, and furthermore, the release agent of the adhesive layer in a portion where the sheet-like porous body overlaps. Is desirably different from the other parts. That is, especially the upper layer side of the overlapping portion is the edge of the sheet-like porous body, and is a site where high adhesive strength is required. Therefore, this portion is a portion where importance is placed on the adhesive strength rather than the permeability of the release agent, and the other portions are portions where importance is placed on the permeability of the release agent rather than the adhesive strength. In this case, there is a concern that the supply of the release agent may be insufficient at the overlapped portion, but there is actually no such concern. The reason is that the release agent applying roller supplies the release agent to the other rotator while rotating itself, and thus does not always supply the release agent to the other rotator by the overlapping portion. What is necessary is just to make sure that the circumference of the outer surface of the release agent application roller and the circumference of the other rotating body do not form a simple integer ratio.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
In the present embodiment, the present invention is embodied as an oil supply roller for supplying release oil to a fixing belt in a fixing device of an image forming apparatus using toner.

First, the outline of the image forming apparatus will be described. The image forming apparatus according to the present embodiment has an image forming station 4 for each of four colors as shown in a schematic sectional view of FIG.
This is a tandem type full color printer provided with C, 4M, 4Y, and 4K. That is, each image forming station 4
Image data input from outside (a personal computer or the like) is input to C, 4M, 4Y, and 4K via a controller 7 and a print head controller 8. Thereby, each image forming station 4C, 4M, 4
Y and 4K create toner images of the respective colors. The toner images of each color are sequentially transferred and superimposed on the transfer belt 6 rotating in the direction of arrow A in FIG.

In synchronization with this, one sheet of printing paper is taken out of the paper cassette 1 and sent to the nip portion between the transfer roller 3 and the transfer belt 6 via the paper feed roller 2. There, the superimposed toner image is transferred from the transfer belt 6 onto the printing paper. The printing paper that has received the superimposed toner image is discharged onto the paper discharge tray 9 via the fixing device 5 of the belt fixing type. In the fixing device 5, the superimposed toner image is melted by heating and is also pressurized to be fixed as a full-color image on printing paper.

As shown in FIG. 2, the fixing device 5 includes a fixing belt 10 which is wound around two tension rollers 15 and 16 and rotates in the direction of arrow A in FIG. I have. The printing paper passes through the nip portion between the fixing belt 10 and the opposing roller 11. Stretch roller 1
5 and the opposing roller 11 have a built-in heater as a heat source for fixing. Further, an oil supply roller 12 that supplies release oil to the fixing belt 10 is provided. The oil supply roller 12 supplies release oil to the fixing belt 10 via the donor roller 14. Also,
The donor roller 14 is provided with a cleaning roller 13 for wiping off excess release oil.

The release oil has a viscosity of 100 to 300 cSt.
Degree of dimethyl silicone oil. In general,
Dimethyl silicone oil having a peak molecular weight in the range of 5 × 10 ³ to 1 × 10 ⁴ has such a viscosity. For example, a model “KF-96SS-1” manufactured by Shin-Etsu Chemical Co., Ltd.
00CS "(viscosity 100 to 110 cSt (25 ° C))
Can be used.

Next, the oil supply roller 12 will be described in detail. The oil supply roller 12 includes a metal core 21,
It has a multilayer structure including a base material 22, a felt layer 23, and a surface layer 25. The surface layer 25 forms a wrap portion at a part on the circumference. Although not shown in FIG. 2 because it is thin, the adhesive layer 2 is provided between the felt layer 23 and the surface layer 25.
4 (see FIG. 3). FIG. 3 shows a portion outside the wrap portion. In the wrap portion, as shown in FIG. 4, the adhesive layer 24 and the surface layer 25 are superposed on the felt layer 23. The overlapping upper portion of the adhesive layer 24 has characteristics slightly different from other portions as described later. The metal core 21 forms a rotation axis of the oil supply roller 12, and is a plated iron bar having a diameter of about 8 mm (for example, a SUM22 steel material is used as an ES rod).
Ni-treated). Further, the core metal 21 may be made of stainless steel.

The substrate 22 is a cylindrical ceramic member having a function of impregnating and storing release oil. For example,
A product having a large pore ratio of 22 to 24%, a porosity of 68 to 72%, and a bulk density of about 0.78 g / cm ³ , which is a product name of “CELLAR AC” manufactured by Nichias Corporation, can be used.

The felt layer 23 has a function of impregnating the release oil and moving the release oil stored in the base material 22 to the adhesive layer 24 and the surface layer 25.
For example, model "OX-10" manufactured by Nippon Felt Industry Co., Ltd.
70 "can be used. This is a mixed composition of aramid fiber of 2.2 decitex and fiber of 0.88 decitex. Here, a sheet having a thickness of 2.8 ± 0.2 mm (limit is 0.5 to 5 mm) and a basis weight of 680 ± 40 g / m ² is used. Then, this material is formed into a belt shape having a width of 30 mm, which is spirally wound around the side surface of the base material 22 to form a felt layer 23. The base material 22 and the felt layer 23 form a release oil holding layer.

The surface layer 25 is a layer directly in contact with the donor roller 14. For example, Sumitomo Electric Fine Polymer Co., Ltd.'s product name “Poreflon sheet”, model “WP-0”
20-80 "can be used. This is a biaxially expanded porous membrane of PTFE, having a thickness of 70 to 95 μm, a porosity of 70 to 85%, and an air permeability of about 11 ± 3 seconds in Galley value. In the present embodiment, a rectangular sheet having sides slightly longer than the axial length and the circumferential length of the oil supply roller 12 is used. This type of PTFE sheet includes a sheet manufactured by a biaxial expansion process and a sheet manufactured by a uniaxial expansion process. However, when a uniaxially stretched one is used, the oil supply property of the oil supply roller 12 tends to be unstable. It is considered that the uniaxial extension is due to a bias in the shape and direction of the hole.

The adhesive layer 24 is composed of the felt layer 23 and the surface layer 25.
And has a function of controlling the degree of movement of the release oil from the felt layer 23 to the surface layer 25. The adhesive layer 24 is made of an adhesive obtained by mixing silicone rubber and dimethyl silicone oil.

First, the silicone rubber will be described. Silicone rubber is the main component of the adhesive. For example, Toray
Model “SE17” manufactured by Dow Corning Silicone Co., Ltd.
00 ”,“ CY52-228 ”,“ SY52-00 ”
5 "," SE1731 "," CY52-210 "," S
E1740 "and" SE9175 "can be used.

Next, dimethyl silicone oil will be described. The dimethyl silicone oil mixed in the adhesive has a role of securing a moving path of the release oil in the adhesive layer 24. For this reason, it is desirable to use oil having a larger molecular weight than dimethyl silicone oil as the release oil. If the molecular weight is small, the movement path is so narrow that sufficient permeability cannot be exhibited. In other words, in terms of viscosity, a material having a higher viscosity than dimethyl silicone oil as a release oil should be used. In the present embodiment, the viscosity of the release oil is 100 to 11 as described above.
Since the viscosity is 0 cSt, the viscosity of the dimethyl silicone oil as the adhesive is preferably about 1,000 to 200,000 cSt. Above all, the range of 50,000 to 150,000 cSt is preferable for dispersing the silicone varnish better and realizing stable oil applicability. Generally, dimethyl silicone oil having a peak molecular weight in the range of 2 × 10 ^{4 to} 1.5 × 10 ⁵ has such a viscosity. For example, a model “KF-96H-10” manufactured by Shin-Etsu Chemical Co., Ltd.
10,000 CS "(viscosity is 95,000 to 105,000 cSt)
(25 ° C.)) can be used.

Next, the permeability of the release oil in the adhesive layer 24 will be described. The permeability of the release oil in the adhesive layer 24 depends on the mixing ratio of silicone rubber and dimethyl silicone oil. That is, when the amount of silicone rubber is large, the permeability is low, and when the amount of dimethyl silicone oil is large, the permeability is high. Therefore, depending on the mixing ratio at which the adhesive layer 24 is formed, the oil supply roller 12
It is possible to control the coating property. Alternatively, the adhesive layer 24
The same is also possible depending on the thickness of the substrate. That is,
When the adhesive layer 24 is thick, the permeability is low, and when the adhesive layer 24 is thin, the permeability is high. However, in any case, the degree of permeability has a relationship opposite to the strength of the adhesive strength.

First, the mixing ratio will be described. When the present inventors tested the relationship between the mixing ratio and the permeability, the results shown in FIG. 5 were obtained. The horizontal axis in FIG. 5 is the weight percentage of dimethyl silicone oil to silicone rubber in the adhesive constituting the adhesive layer 24. This shows that the higher the content of dimethyl silicone oil, the higher the permeability of the release oil, and conversely, the lower the content of dimethyl silicone oil, the lower the permeability of the release oil. This is presumably because the higher the content of dimethyl silicone oil, the greater the number of movement paths of the release oil in the adhesive layer 24.

The relationship between the mixing ratio and the adhesive strength was also tested. The result was as shown in FIG. The horizontal axis in FIG. 6 is the same as the horizontal axis in FIG. This indicates that the higher the content of dimethyl silicone oil, the lower the adhesive strength, and conversely, the lower the content of dimethyl silicone oil, the higher the adhesive strength. This is considered to be because the adhesive force of the adhesive is exerted by the silicone rubber.

Next, the thickness of the adhesive layer 24 will be described.
When the inventor tested the relationship between the thickness and the permeability, the result shown in FIG. 7 was obtained. The horizontal axis of FIG. 7 indicates the thickness of the adhesive layer 24 by the weight per area. This indicates that the thicker the adhesive layer 24, the lower the permeability of the release oil, and conversely, the thinner the adhesive layer 24, the higher the permeability of the release oil. The test results on the relationship between thickness and adhesive strength are shown in FIG.
Was as shown in FIG. The horizontal axis in FIG. 8 is the same as the horizontal axis in FIG. From this, it can be seen that the thicker the adhesive layer 24, the stronger the adhesive strength, and the thinner the adhesive layer 24, the weaker the adhesive strength.

The test of the permeability shown in FIGS.
This was performed as shown in FIG. That is, the felt layer 2
A test piece was obtained by bonding a felt lump 123 of the same material as that of No. 3 and a PTFE sheet 125 of the same material as the surface layer 25 with an adhesive 124. The felt lump 123 is immersed in the same dimethyl silicone oil 120 as the release oil,
A piece of silicone rubber 126 and a weight 127 were placed on top and pressed. In this state, the release oil content of the silicone rubber piece 126 after a predetermined time had elapsed was measured. The test for the adhesive strength in FIGS. 6 and 8 was performed as shown in FIG. That is, the manufactured oil supply roller 12 itself was used as a test piece. Then, while the surface layer 25 was peeled off by the digital force gauge 128, the pulling force at that time was monitored. The displacement at that time was monitored by the laser displacement meter 129.

In this embodiment, as shown in FIG. 11, the release oil permeability and adhesive strength of the adhesive differ depending on the position of the oil supply roller 12.
That is, at both ends 30, 30 and the wrap 31,
Compared to the other parts 32, the adhesive layer 24 is designed to emphasize the adhesive strength even if the permeability of the release oil is slightly sacrificed. More specifically, the upper adhesive layer 24 in FIG. 4 is made of an adhesive with an emphasis on adhesive strength, and the lower adhesive layer 24 may be the same adhesive as the other parts 32 in FIG. . This is because these portions are close to the edge of the surface layer 25 and therefore require strong adhesive strength. On the other hand, since the other portions 32 do not have to be so strong in adhesive strength, it is better to attach importance to the permeability of the release oil.

Therefore, for example, an adhesive having a content of dimethyl silicone oil (percentage by weight of silicone rubber) of 50% or less is used for both ends 30, 30 and the wrap portion 31, and the other portion 32 contains dimethyl silicone oil. An adhesive having a ratio of about 70 to 100% is used.
As a result, the oil supply roller 12 can be obtained in which the adhesion strength is emphasized at the both ends 30, 30 and the wrap portion 31, and the permeability of the release oil is emphasized at the other portions 32. Or,
The content of dimethyl silicone oil may be made uniform, and instead, the amount of the adhesive applied to the surface layer may be made different. In this case, for example, the application amount at both ends 30, 30 and the wrap portion 31 is set to about 120 to 150 g / m ^2, and the application amount at the other portion 32 is set to about 60 to 90 g / m ² .

The width E of both ends 30, 30 is 3 to 1
About 0 mm is appropriate. If it is not enough, the adhesive strength at the end may be insufficient and may be a starting point of peeling. Conversely 10mm
Larger ones do not make much sense and simply lead to larger sizes. It is desirable that the width P of the other portion 32 is ensured to be equal to or greater than the maximum sheet passing width. However, since an actual print often has a margin at the end, there is no significant problem if the “oil application width” in FIG. Further, at least one of the ratio of the outer peripheral length of the oil supply roller 12 to the outer peripheral length of the donor roller 14 (FIG. 2) and the ratio of the outer peripheral length of the donor roller 14 to the outer peripheral length of the fixing belt 10 is a simple integer. Desirably, no ratio is made. Fixing belt 1
This is to prevent the release oil from being supplied by the wrap portion 31 each time to the same location of zero.

As described in detail above, in this embodiment, the surface layer 25 of the oil supply roller 12 is
An adhesive layer 24 made of a mixed adhesive of silicone rubber and dimethyl silicone oil is provided between the surface layer 25 and the felt layer 23 which is a part of the release oil holding layer, while being made of an E sheet. As described above, differences are provided between the release oil permeability and the adhesive strength of the adhesive layer 24 depending on the portions. That is, the end portions 30, 30 and the wrap portion 31, which require a strong adhesive strength, use an adhesive with a reduced content of dimethyl silicone oil or increase the thickness of the adhesive layer 24 as compared with the other portions 32. ing. This prevents the surface layer 25 from peeling off from the edge portion, while ensuring the applicability of the release oil in the other portion 32. Here, since the portions where the adhesive strength is emphasized are the both ends 30, 30, there is no problem in the coating property of the release oil in the paper passing range (particularly, the range where the toner image exists). Further, since the wrap portion 31 occupies only a small portion in the circumferential direction, this does not actually affect the applicability of the release oil.

Further, since the portion where the adhesion strength is emphasized is provided as described above, it is not necessary to use a cylindrical film as the surface layer 25, and a quadrilateral PTFE film is sufficient. As a result, the present invention is free from the restrictions on the roller diameter and the film thickness when a cylindrical film is used. Thus, the oil supply roller 12 having a sufficient adhesive strength of the surface layer 25, always being able to appropriately supply the release oil, and having a long life is realized.

The present embodiment is merely an example and does not limit the present invention. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, in the present embodiment, the holding layer for the release oil has a two-layer structure of the ceramic base material 22 and the felt layer 23 outside the base material 22. However, the holding layer may be constituted only by the felt layer 23. In addition, adhesive layer 2
As the adhesive constituting 4, a mixture of silicone varnish and dimethyl silicone oil may be used instead of a mixture of silicone rubber and dimethyl silicone oil. Also, the raw materials used in each part may be replaced with other materials having the same function. In addition, the donor roller 14
Alternatively, the release oil may be directly supplied to the fixing belt 10 without any intervention, or may be applied to a fixing device other than the belt fixing method.

[0034]

As is apparent from the above description, according to the present invention, a sufficient surface layer adhesive strength can be obtained without using a cylindrical film, and an appropriate release agent supply amount can always be exhibited. A release agent application roller having a long life is provided.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an image forming apparatus.

FIG. 2 is a schematic configuration diagram of a fixing device.

FIG. 3 is a conceptual sectional view showing a structure of an oil supply roller (a portion outside a wrap portion).

FIG. 4 is a conceptual sectional view showing a structure (wrap portion) of an oil supply roller.

FIG. 5 is a graph showing the relationship between the content of dimethyl silicone oil in the adhesive layer and the permeability of release oil.

FIG. 6 is a graph showing the relationship between the content of dimethyl silicone oil in the adhesive layer and the adhesive strength.

FIG. 7 is a graph showing the relationship between the thickness (area density) of an adhesive layer and the oil permeability of a release oil.

FIG. 8 is a graph showing the relationship between the thickness (area density) of an adhesive layer and the adhesive strength.

FIG. 9 is a diagram illustrating a method for testing the release oil permeability of an adhesive layer.

FIG. 10 is a diagram illustrating a method for testing the adhesive strength of an adhesive layer.

FIG. 11 is a diagram illustrating portions of the oil supply roller having different adhesive oil permeability of the adhesive layer.

[Explanation of symbols]

 12 Oil supply roller 23 Felt layer 24 Adhesive layer 25 Surface layer 30 Both ends 31 Wrap

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mamoru Fukaya 2-3-13 Azuchicho, Chuo-ku, Osaka City International Building Minolta Co., Ltd. (72) Inventor Takashi Isogai 2-3-3 Azuchicho, Chuo-ku, Osaka-shi No. 13 Osaka International Building Minolta Co., Ltd. F-term (reference) 2H033 AA09 AA23 AA39 BA42 BA43 BA46 3J103 AA02 AA15 AA23 AA51 GA57 GA58 GA60 GA73 HA04 HA11 HA18 HA53 HA60

Claims (4)

[Claims] 1. A release agent application roller for applying a release agent to a rotating body, a surface layer constituting a surface, a holding layer located inside the surface layer and having a function of holding the release agent,
A release agent application roller, comprising: an adhesive layer that adheres the surface layer and the holding layer, wherein the adhesive layer is provided with a portion having different release agent permeability. 2. The release agent applying roller according to claim 1, wherein a portion where the adhesive layer has a different permeability from the other portion is provided at an end portion in the axial direction of the roller. Release agent application roller. 3. The release agent applying roller according to claim 1, wherein said surface layer is made of a sheet-like porous body, and said adhesive layer is released at a portion where said sheet-like porous body overlaps. A release agent applying roller, wherein the agent has a different permeability from other parts. 4. The release agent applying roller according to claim 1, wherein the release agent is silicone oil, the adhesive layer contains silicone oil, and the adhesive layer has a permeability of the release agent. A release agent application roller, wherein the content of the silicone oil is different depending on the area of the release agent.