JPH07120120B2 - Offset prevention roller for electrophotographic fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) The present invention has an oil-impregnated layer, and this oil-impregnated layer provides an offset preventing oil such as silicone oil to a fixing roller of an electronic copying machine or other electrophotographic apparatus. The present invention relates to a roller used to remove the toner of the image printed on the surface of the fixing roller while being supplied, and improve the offset preventing ability of the fixing roller and the cleaning ability for the fixing roller.
It is an object of the present invention to provide a means for maintaining these capabilities of the fixing roller for a long period of time and also improving the storage stability of the offset prevention roller.

The oil-impregnated layer is coated on the peripheral wall of the hollow core body, and the offset prevention oil (hereinafter simply referred to as oil) accommodated in the core body is passed through the through holes and the oil-impregnated layer formed in the peripheral wall in a distributed manner. An offset prevention roller that supplies residual toner to the fixing roller K ₁ or K ₂ of the fixing device as shown in FIG.
Is shown in Japanese Patent Laid-Open No. 60-1 disclosed by the inventor.
It is known from Japanese Patent No. 36782. Further, such an offset prevention roller can significantly reduce the size of the conventional offset prevention means for supplying the oil guided from the oil storage tank to the fixing roller with a coating device such as a felt, so that the overall size and economy of the electrophotographic apparatus can be reduced. It greatly contributes to the improvement of sex.

However, it has been gradually found that such an offset prevention roller also has the following drawbacks. That is,
The above-mentioned offset prevention roller is incorporated in an electrophotographic apparatus, or as a single unit for warehouse storage and general transportation, especially for long-term shipment transportation during shipping, because of continuous leaching of oil from the body into the oil-impregnated layer, Excessive oil accumulation in the oil impregnated layer causes the paper to be significantly contaminated with oil during its use.

Next, as a second drawback of the offset prevention roller described above, even if the oil is uniformly distributed and impregnated on the roller surface of the offset prevention roller at the initial stage of paper passing to the fixing roller equipped with this, continuous As the number of sheets passed increases, the distribution becomes less uniform, leading to the distribution pattern of oil stains as shown in FIG. That is, 14 points
As for the area (1), a large amount of oil is adsorbed in this area because the toner is adsorbed in a large amount in this area, while the oil supply in other areas indicated by the shaded areas is insufficient, and eventually the roller surface of the fixing roller is The cleaning effect rapidly decreases, and the offset to the paper becomes noticeable long before the entire surface of the oil supply roller is saturated with the toner.

The above-mentioned drawbacks of the conventional oil supply roller having a single-layer oil impregnated layer have been dealt with in recent years by the Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Publication No. 8 and Japanese Utility Model Publication No. 61-104469, by limiting the oil leaching amount by configuring the oil-impregnated layer into multiple layers that differ in oil permeability or retention. Ideas such as additions have been proposed.

That is, according to the example of Japanese Utility Model Laid-Open No. 61-104469, the oil-impregnated layer is composed of three layers, the inner layer is paper with low fiber density (7 rolls), and the intermediate layer is paper with high fiber density (2 rolls). ), The surface layer has a fiber density of polyamide fiber felt (thickness 1 mm), and attempts to limit the oil transfer amount to the surface layer by making the oil permeability of the intermediate layer poor.

On the other hand, according to the embodiment disclosed in JP-A-60-144778, the oil-impregnated layer has two layers, an inner layer made of a fibrous sheet having a thickness of 0.4 mm and a surface layer made of a silicone rubber sponge having a thickness of 4 mm. It is intended to limit the amount of oil transfer to the roller surface corresponding to the surface of the silicone rubber sponge by appropriately setting the open cell rate of the silicone rubber sponge.

However, according to the experiments by the inventor, when the former (actually developed No. Sho 61-104469) fixing roller equipped with rollers is continuously fed, it is apparent from the control example to the embodiment of the present invention described later. In addition to the uneven distribution of oil on the roller surface of the oil supply roller, after the roller was left at room temperature for about 3 months, the amount of oil impregnated in the surface layer was almost 2% of the amount previously impregnated. That is, after being left for 6 months, it almost reaches 5 times, and when it is left as it is, the fixing roller cannot be mounted and used. This fact improves the oil distribution to the surface of the fixing roller during paper feeding, even if a plurality of layers are formed and the density of each layer is changed, as long as the oil permeation diffusivity between fibers is utilized. It also indicates that it is not possible to prevent excessive accumulation of oil in the surface layer after being left for a long time.

In the latter case (JP-A-60-144778), since the oil diffusivity in the sponge rubber layer is significantly lower than that in the fiber layer, the problem of excessive oil accumulation in the surface layer after being left for a long time does not occur. However, due to the poor oil diffusivity, the distribution of oil on the roller surface is similarly poor during continuous paper feeding to the fixing roller, as described below. In addition to the fact that the sponge elastic material itself is much inferior in toner adsorbability to the fiber and the pores to be supplemented with the toner are significantly larger than the toner particles, not only the cleaning action on the fixing roller is incomplete. However, there is a drawback in that the pores are clogged with paper dust, which prevents the oil from leaching to the roller surface. Furthermore, while the fixing roller is used at a high temperature as high as 180 to 220 ° C. during use, a sponge of an elastic material that is durable to such a high temperature cannot be obtained, and therefore, it shows rapid deterioration. Therefore, it cannot be said that it cannot withstand long-term use.

Therefore, the present invention aims to eliminate the above-mentioned conventional drawbacks of the offset prevention roller which is mounted on the fixing roller, supplies oil to the fixing roller, and removes the toner remaining on the roller surface. It is configured like.

(Structure of the Invention) The present invention will be described below with reference to FIGS. 1, 2, and 4 showing cross sections of an embodiment of the present invention. Use metal such as iron or aluminum or a suitable engineering plastic as the material for the body. On the cylindrical wall 11 of the core body, through holes 12 having a hole diameter of 0.3 to 1.5 mm are dispersedly formed. Reference numeral 2 denotes an oil-impregnated layer, in which an intermediate layer 22 made of a heat-resistant elastic sponge is interposed between an inner layer 21 made of a high-density fiber layer and a surface layer 23 made of a low-density fiber layer. For the fiber layer of the inner layer 21, it is preferable to use one having a high density such as 0.5 to 1.0 g / cm ³ , and to form it by winding polyamide paper, Japanese paper, or the like several times. The middle layer 22 is preferably made of a heat-resistant elastic sponge such as silicone rubber or fluororubber and has a low open cell rate and a thickness of 0.5 to 3.0.
It is good to set it to about mm. As a material for the fiber layer forming the surface layer 23, a polyamide felt having a low density and a coarse texture such as 0.2 to 0.4 g / cm ³ is optimal. In addition, as the oil A to be contained in the core body 1, a highly viscous silicone oil such as 30,000 to 500,000 cs is most suitable, and usually 80% or less of the inner volume of the core body should be enclosed.

The present invention is configured as described above, but when it is mounted on the fixing roller and used, in order to supply an appropriate amount of oil to the fixing roller evenly from the beginning of paper feeding, Apply a small amount of oil evenly on the roller surface of the offset prevention roller in advance.

The operation of the present invention will be described below with reference to FIG. 4. This figure shows that when the offset prevention roller S according to the present invention is in contact with the lower fixing roller K ₁ from above, It shows the aspect of the fault of the main part of the tubular wall part.

That is, the oil A whose viscosity has been lowered by the heating of the fixing roller K ₁ permeates and diffuses toward the surface layer 23 through the through holes 12, but first, the flow rate is increased in the dense fiber layer forming the inner layer 21. Although it diffuses in a narrow funnel shape while being regulated, since the intermediate layer 22 formed of sponge rubber is difficult to permeate at points other than its pores, it follows the boundary surface 3 between the inner layer 21 and the intermediate layer 22 and It spreads significantly as shown in the drawing.
Although the sponge rubber of the mid layer 22 is difficult to permeate in a state of being left naturally, the offset prevention roller S is a fixing roller.
Since it rotates while being pressed against K ₁ , the position of the peripheral surface receiving the pressure changes every moment, so the pores of the sponge rubber are repeatedly compressed and opened, and a kind of pump action is performed here. However, this pumping action works well in the direction of the thickness where the oil passage distance is small and sends the oil well to the surface layer 23, but the passage distance is incomparably larger than the layer thickness, and therefore the passage resistance is large. Since it does not work well in the direction along the layer that is large, the oil does not diffuse and penetrate in the direction along the layer so much that it corresponds to the middle of two through holes 12, 12 adjacent to each other. The intermediate portion 13 of the intermediate layer 22 is hardly impregnated with oil, or remains impregnated significantly. However, according to the present invention, since such an intermediate layer 22 is in contact with the surface layer 23 composed of a low-density fiber layer having extremely excellent permeability, the intermediate layer 22
The oil sent out from a fairly wide portion with a good impregnation state at 22 is transferred to the surface layer 23 and at the same time diffused in the direction along the layer in the surface layer 23, and as a result, near the surface layer of the surface layer 23 pressed against the fixing roller K _1. Oil is evenly distributed on the roller and is evenly supplied to the roller surface of the fixing roller K ₁ . Incidentally, as described above, in the sponge rubber layer constituting the intermediate layer 22, a region where the impregnation of oil is poor remains broadly because the surface of the roller of the control example described later is passed through the fixing roller many times. This was confirmed by the fact that the toner dot-like state shown in FIG. 8 was exhibited.

Next, when the roller according to the present invention is left for a long period of time for storage and transportation, the core body 1 is inserted through the inner layer 21 and the intermediate layer 22.
Although the oil A in the inside leaches out and is transferred and accumulated in the surface layer 23, the sponge rubber layer forming the intermediate layer 22 is difficult for oil to pass through in the natural state, so as can be seen from the characteristic line of the embodiment in FIG. The amount of transfer accumulation is very small, so even if the roller is left on the fixing roller for a long period of time and used, oil stains on the paper do not occur, and an appropriate amount of oil supply capacity to the fixing roller is maintained from the beginning. Can be demonstrated.

Further, according to the present invention, the high-density fiber layer of the inner layer 21 exerts a regulation effect on oil passage, but the sponge layer of the intermediate layer 22 has a more remarkable oil regulation action than such a high-density fiber layer. As described above, the wasteful consumption of oil can be prevented, and a long oil supply life can be secured.

Furthermore, according to the present invention, since the intermediate layer 22 of sponge rubber is interposed between the surface layer 23 and the inner layer 21, due to the soft elasticity of the sponge rubber layer, the surface layer that contacts the fixing roller K _1. A sufficient nip width is ensured by the deformation of 23, and therefore, the surface layer 23 exhibits a good cleaning action.

Further, the soft elastic sponge is inferior in heat resistance to the fiber and is relatively quickly deteriorated by high temperature. However, according to the present invention, such sponge layer does not directly contact the high temperature fixing roller and the surface layer Since the 23 fibrous layers are protected, the progress of deterioration is alleviated, and the above-mentioned offset prevention capability required for the fixing device can be maintained for a long period of time.

The results of one embodiment of the present invention are described below in comparison with the experimental results of several conventional control examples.

(Embodiment) Referring to FIG. 1 and FIG. 2, reference numeral 1 is a hollow aluminum-made core body having an inner diameter of 22 mm, an outer diameter of 24 mm and a surface length of 320 mm, and supporting shafts 15 and 15 for supporting. Forty through holes 12 having a diameter of 1 mm are dispersedly arranged in the cylinder wall 11. Oil impregnated layer 2 is the inner layer
21, the intermediate layer 22, the surface layer 23, the inner layer 21 has a thickness of 0.1 mm,
A polyamide paper (Nomex paper NX-6060 manufactured by Kureha Senii Co., Ltd.) having a fiber density of 0.6 g / cm ³ is wound five times. The intermediate layer 22 is made of silicone sponge rubber having a thickness of 1 mm and an Asker hardness of 30 degrees. The surface layer 23 is made of polyamide felt (Nomex felt manufactured by Kureha Senii Co., Ltd.) having a thickness of 1.5 mm and a fiber density of 0.32 g / cm ³ . 80 g of silicone oil (SH-200 manufactured by Toray Silicone Co., Ltd.) having a viscosity of 300,000 cs is enclosed as the oil A inside the core body 1.

For the sake of simplicity, the following comparative examples are not shown, so please refer to FIG. 1 and FIG. 2 which illustrate the above embodiment.
In these comparative examples, the same parts as those in the examples are denoted by the same reference numerals.

(Comparative Example 1) The same polyamide paper as the above-mentioned example was wound around the same peripheral surface of the core body 1 as the above-mentioned example as the inner layer 21 five times as in the above-mentioned example, and the above-mentioned example was formed on this inner layer 21. The same polyamide felt layer as above was provided as the surface layer 23. Since the intermediate layer 22 is not provided, the oil impregnated layer 2 is composed of two layers. Oil A is of the same quality and amount as in the example.

(Comparative Example 2) A fiber density of 0.
Wrap 45g / cm ³ Washi paper to a layer thickness of 1.0mm.
As 22 a polyamide paper having a fiber density of 0.8 g / cm ³ (Nomex paper manufactured by Kureha Senii Co., Ltd.) was wound to have a thickness of 0.5 mm, and as the surface layer 23 thereon, the same material and the same thickness as those in the above-mentioned Examples were used. Of the polyamide felt layer. Oil A is of the same quality and amount as in the above-mentioned embodiment.

(Comparative Example 3) The core body 1 is a hollow cylinder made of aluminum and has an inner diameter of 17 mm and an outer diameter of 19 mm.
mm, surface length 320 mm, and the number of through holes 12 (diameter 1 mm) is 16. The inner layer 21 is formed by winding polyamide paper with a fiber density of 0.4 g / cm ³ (Nomex paper manufactured by Kureha Senii Co., Ltd.) to a thickness of 0.5 mm, and a thickness of 4 m as a surface layer 23 on the inner layer 21.
A silicone sponge rubber layer having m and a hardness of 30 degrees was provided. There is no intermediate layer 22. The oil A contained in the core body 1 is of the same quality as in Example 1 and is 50 g.

Here, the test methods and test results of the above-mentioned examples and control examples will be described.

First, in order to examine the presence or absence of uneven oil supply to the fixing roller, the example and each control example were incorporated in the same electronic copying machine, and a paper passing test was performed on 10,000 sheets each. When the offset preventing roller was removed after 10,000 sheets of paper had passed and the roller surface was observed, toner smear occurred in the roller surface of the example at a uniform density on the entire peripheral surface, while in Comparative Examples 1 to As shown in FIG. 8, the roller surface of No. 3 has a thick hang point 15 due to the toner stain around the position corresponding to the through hole 12 provided in the core body.
15 In the middle of each other, the toner stain is very weak. This is because in the embodiment, as shown in FIG. 4, the manner of oil impregnation near the surface of the surface layer 23 is almost uniform, and therefore the entire roller surface adsorbs toner evenly, whereas the contrast is in contrast. In Example 1, since the oil-impregnated layer 2 is a multi-layer, all the layers are formed by the fiber layer having good permeability, so that the oil supplied from the through holes 12 is not laterally diffused but the roller surface. It was presumed that this was because it permeated almost straight toward. FIG. 5 shows an oil permeation pattern in the oil-impregnated layer 2 of Comparative Example 1. This situation is the same for the oil permeation pattern in Comparative Example 2 shown in FIG. 6, and even if the oil-impregnated layer 2 is composed of three layers having different fiber densities, the results obtained are the same as those of the multi-layer structure. There is no big difference. Further, the oil permeation pattern in Comparative Example 3 is shown in FIG. 7, but since the surface layer 23 of the oil impregnated layer 2 composed of two layers is formed of sponge rubber having poor oil permeability, Since the oil to be leached is prevented from moving in the direction of the surface layer 23, it diffuses in the surface direction at the boundary surface with the surface layer 23, and at the boundary surface, the diffusion is significantly wider than the cross-sectional area of the through hole 12. Face 16
To form. Thus, oil has such a wide diffusion surface.
It starts to permeate into the surface layer 23 starting from 16, but since the sponge rubber of the surface layer 23 has poor lateral diffusion,
The roller surface, which is the surface of No. 23, does not show a great spread, and eventually, due to the uneven oil supply, toner stain such as a point 15 shown in FIG. 8 is exhibited.

The occurrence of offset in passing the paper to the fixing roller is mainly due to the unevenness of the oil supply to the fixing roller, but when the roller of each of the above-mentioned Examples and each control example was attached to the fixing roller, a paper passing test was conducted. In the example, the offset finally occurred at about 150,000 sheets, whereas the offset occurred at about 80,000 sheets in Comparative Examples 1 and 2, and about 7,000 sheets in Comparative Example 3. Further, in Comparative Example 3, occurrence of paper jam due to toner and paper dust accumulated on the roller surface of the fixing roller was observed after the number of passed sheets exceeded 12,000.

Next, when the amount of oil supplied to the paper by the rollers of the above-mentioned example and each control example was examined, the results shown in FIG. 9 were obtained. That is, in Comparative Examples 1 and 2, the oil supply amount was a little excessive at the beginning of the paper feeding, but the oil supply amount was rapidly decreased to about 125
While the oil supply capacity is lost after 1,000 sheets, the decrease in the oil supply amount is gradual in the embodiment, and the necessary minimum supply amount is still secured for the 150,000 sheets passed. In Comparative Example 3, an appropriate amount was supplied at the start of paper feeding, but this oil supply capacity was rapidly lost due to deterioration of the sponge rubber due to heat reception, and the test was stopped at 17,000 sheets due to paper jam. It came to unavoidable.

Finally, the state of oil transfer from the inside of the core body 1 to the surface layer 23 after the roller was left for a long time was tested.
I got 10 figures. As a test method, Example and Control Examples 1 and 2 in which the surface layer was impregnated with 2.0 g of the oil from the outside so as to be ready for use at any time were taken and stored at room temperature for 6 months. As the test results show,
For Control Examples 1 and 2, the oil impregnation amount gradually increased during the period, and after 6 months, Control Example 1 had an impregnation amount of 11.3 g (oil transfer amount was 9.3 g) and Control Example 2 had an impregnation amount of 10.1 g (oil transfer amount). The amount was 8.1 g), while the oil transfer amount was small according to the example, and the impregnation amount after 6 months was 3.4 g (transfer amount 1.4 g). In addition, in Comparative Example 3, even if the sponge rubber of the surface layer 23 is hardly absorbed even if the oil is applied to the surface layer 23 at the start of the application, it is left without application. It was considered that there was almost no stickiness of the oil when touched, and the problem of the transfer of the oil inside to the surface layer 23 was practically negligible. After the sheets were left for 6 months, the fixing roller was attached to each of the examples and the control examples 1 and 2, and when the paper was passed, the control examples 1 and 2 showed remarkable oil stains on the paper, while the oil was used in the example. No dirt was generated.

(Effect of the Invention) As is clear from the examination of the above test results, according to the present invention, the oil can be uniformly spread over the entire roller surface of the fixing roller, and a large cleaning effect can be exhibited. At the same time, not only is it possible to supply a small, proper and almost even amount of oil to the fixing roller from beginning to end, but deterioration of the member is avoided during use at high temperatures, and the surface layer remains even after being left for 6 months or for a long time. Excess oil does not accumulate. Thus, according to the present invention, it is possible to maintain the excellent offset preventing ability for a large amount of paper in the fixing device, and at the same time, to endure unused for a long time. It is possible to provide an excellent anti-offset means for an electrophotographic device.

[Brief description of drawings]

FIG. 1 is an axial sectional view of an embodiment of an offset prevention roller according to the present invention, FIG. 2 is an axial sectional view of the same, FIG. 3 is a skeleton view of a fixing device during sheet feeding, and FIG. The figure which shows the oil distribution pattern in the oil impregnated layer of the Example described in the detailed description section, FIG. 5 is the figure of the comparative example 1 corresponding to FIG. 4, FIG. 6 is the same figure of the comparative example 2, FIG. 7 is also a view of Comparative Example 3, and FIG. 8 is a plan view of a roller showing a mode of toner stain of each Comparative Example taken out during the use,
FIG. 9 is a test result diagram of the oil supply amount to the paper by the fixing roller equipped with the examples and the respective control examples, and FIG. 10 is a graph showing the oil amount in the long-term storage test of the examples, the control examples 1 and the control examples 2. It is a test-result diagram of transfer to the surface layer. A is oil, S is an offset prevention roller, K ₁ and K ₂ are fixing rollers, l is a heat source lamp, P is paper, t is toner,
1 is a core body, 11 is a cylinder wall, 12 is a through hole, 13 is an intermediate part, 14 is a hand point, 15 is a spindle, 16 is a diffusion surface, 2 is an oil impregnated layer, 21 is an inner layer, 22 is an intermediate layer, 23 is the surface layer.

Continuation of front page (56) Reference JP-A-60-252382 (JP, A) JP-A-60-144778 (JP, A) JP-A-52-119335 (JP, A) JP-A-63-121071 (JP , A) JP 60-136782 (JP, A) Actually opened 60-110854 (JP, U) Actually opened 61-104469 (JP, U) Actually opened 58-10459 (JP, U)

Claims (1)

[Claims] 1. A roller in which a large number of through holes are dispersedly formed in a cylindrical wall of a hollow core body for accommodating an offset preventing oil for fixing an electrophotographic image and the peripheral surface of the cylindrical wall is covered with an oil impregnated layer. In the offset prevention roller of the electrophotographic fixing device, the oil-impregnated layer has an intermediate layer made of a heat-resistant elastic sponge interposed between an inner layer made of a high-density fiber layer and a surface layer made of a low-density fiber layer.