JP2001175104A - Rubber roller for fixing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber roller for fixing which can secure nip width without using sponge rubber and can attain low thermal capacity. SOLUTION: The rubber roller for fixing is distinguished by that a core bar 12 and an elastic layer 14 made of nonfoamed rubber 14a which is disposed at an outer periphery of the core bar 12, has an outer peripheral surface of a prescribed outside diameter and is adjusted to prescribed thermal capacity per unit volume by incorporating a filler 14b of low density and low specific heat therein are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing rubber roller used in a fixing device used for fusing and fixing an unfixed toner on a sheet in a copying machine, a printer, a facsimile or the like, and fixing the unfixed toner on the sheet. .

[0002]

2. Description of the Related Art Conventionally, as a fixing device for an electrophotographic apparatus, a so-called two-color fixing device basically includes two rollers, that is, a heating roller having a built-in heat source and a pressing roller pressed against the heating roller at a predetermined pressure. The present roller structure is employed, and various and various patents have been filed and widely used.

In such a fixing device having a two-roller structure, if an attempt is made to form a nip portion having a predetermined width in a rolling contact portion between the two rollers, an elastic layer made of rubber is provided on one or both of them. It has to be arranged. Conventionally, the heating roller has a built-in heat source, so that the heating roller is made of a heat-resistant rubber layer or a fluororesin layer having good heat resistance, and the pressure roller is made of rubber necessary to remove the nip. It is composed of an elastic layer.

[0004]

Here, it is preferable that the elastic layer of the pressure roller is made of sponge rubber, noting that the above-mentioned nip width is sufficiently secured. That is, the sponge rubber is low in hardness and rich in elasticity, has a very small heat capacity, and thus has a fast thermal response. As a result, when heated, the temperature rises in a short time, and it is possible to reach the required fixing temperature in a short time. This means that when applied to a fixing device, the warm-up time can be reduced, which is very preferable from the viewpoint of recent demand for energy saving.

However, the outer peripheral surface of the elastic layer of the pressure roller is heated to a fixing temperature, for example, around 180 ° C. by the heat received from the heating roller. When the elastic layer made of sponge rubber is heated to a high temperature in this way, it naturally expands, but the degree of thermal expansion differs depending on the part based on the difference in the degree of foaming in the sponge rubber. It will be.

That is, when viewed at a position along the axial direction of the pressure roller, the outer diameter of the pressure roller employing sponge rubber for the elastic layer is different at random, especially immediately after the end of the warm-up operation. That (in other words, uneven)
Becomes

As a result, when the unfixed sheet carrying the unfixed toner is inserted into the nip immediately after the completion of the warm-up operation, the unfixed sheet is wrinkled due to the unevenness of the outer peripheral surface of the pressure roller. Is likely to occur.
When paper wrinkles occur on the unfixed sheet in this way, even if the toner image is fixed, it is no longer possible to use a wrinkled sheet, and fixing failure occurs in a large sense, which is a problem. .

The present invention has been made in view of the above-mentioned circumstances, and a main object of the present invention is to provide a fixing device capable of securing a nip width and achieving a low heat capacity without using sponge rubber. To provide a rubber roller for use.

Another object of the present invention is to provide a fixing rubber roller which can secure a nip width and does not cause paper wrinkles even immediately after completion of warm-up.

Another object of the present invention is to provide a fixing rubber roller capable of securing a nip width and shortening a warm-up time.

[0011]

Means for Solving the Problems To solve the above-mentioned problems,
In order to achieve the object, according to the first aspect, a fixing device according to the present invention has a cored bar, an outer peripheral surface of a predetermined outer diameter, which is disposed on the outer periphery of the cored bar, and has a low density. And a non-foamed rubber elastic layer mixed with a low specific heat filler and adjusted to a predetermined heat capacity per unit volume.

According to a second aspect of the present invention, the fixing rubber roller is characterized in that the outer peripheral surface of the elastic layer is covered with a release layer.

According to a third aspect of the fixing rubber roller according to the present invention, the release layer is formed of a fluororesin.

According to a fourth aspect of the fixing rubber roller of the present invention, the low-density and low-specific-heat filler is a hollow body.

According to the fifth aspect of the present invention, there is provided a fixing rubber roller according to the present invention. The low-density and low-specific-heat filler includes a multi-component glass.

According to the sixth aspect of the present invention, the fixing rubber roller according to the present invention has a density ρ (g / cubic cm) and a specific heat c () in a range from the outer peripheral surface of the elastic layer to a depth of at least 2 mm. J / g · K): 0.77 ≦ ρ ·
The characteristic is set so as to satisfy the relationship of c ≦ 1.32.

According to a seventh aspect of the present invention, in the fixing rubber roller, a low density / low specific heat filler is mixed in a range deeper than 2 mm from the outer peripheral surface of the elastic layer. It is characterized by not being done.

Further, according to the invention, the fixing rubber roller according to the present invention has a density ρ (g / cubic cm) and a specific heat c (J / g · K) over the entire area of the elastic layer.
The characteristic is set so as to satisfy the relationship of 0.77 ≦ ρ · c ≦ 1.32.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fixing rubber roller according to an embodiment of the present invention; FIG.

<< Schematic Description of Fixing Device 10 >> First, as shown in FIG. 1, a fixing device 20 provided with a fixing rubber roller of this embodiment will be described. The fixing device 20 includes a fixing housing (not shown) fixed to a frame of an electronic image forming apparatus (not shown), for example, an electronic printer. A heating roller 22 and a heating roller 22 are provided in the fixing housing. A pressure roller 10 as a fixing rubber roller according to the present embodiment, which is in pressure contact with a predetermined pressure force, is provided.

The heating roller 22 includes an aluminum core 24 and a release layer 26 made of a fluororesin coated on the outer periphery of the core 24. The heating roller 22 is driven to rotate at a predetermined rotation speed by a driving unit (not shown), and has a halogen lamp 28 as a heat source. In this embodiment, the outer diameter of the heating roller 22 is set to a diameter of 25 mm.

On the other hand, as shown in FIG. 2, the pressure roller 10 is tightly bonded to an iron core 12 having a nickel-plated surface and an outer periphery of the core 12 via an adhesive. Cylindrical non-foamed rubber elastic layer 14
And a release layer 16 formed of a fluororesin layer coated on the outer peripheral surface of the elastic layer 14 and having a predetermined thickness. In this embodiment, the elastic layer 14
Is set to 5.5 mm, and the pressure roller 1
The outer diameter of 0 is set to a diameter of 25 mm.

Hereinafter, the elastic layer 14 of the pressure roller 10 will be described.
Will be described in detail with reference to FIG. This elastic layer 14
In this embodiment, a non-foamed rubber 14a represented by a silicone rubber model number: X-34-1279A / B manufactured by Shin-Etsu Chemical Co., Ltd. is used as a base rubber.
In addition, glass balloon 14 as low density and low specific heat filler
Those in which b is uniformly dispersed are used. here,
In this embodiment, a multi-component glass balloon is used as the glass balloon 14b, and specifically, model number: Z-27 manufactured by Tokai Kogyo Co., Ltd. is used. Note that the density of the glass balloon 14b is, in this embodiment,
It is defined not as the apparent density but as the true density measured with each filler alone.

The blending amount of the glass balloon 14b is set to 15 parts in this embodiment. Here, the optimum range of the blending amount of the glass balloon 14b will be discussed in detail later.

Next, a method of manufacturing the pressure roller 10 having the above-described configuration will be described. First, as a raw material of the non-foamed rubber 14a, a silicone rubber manufactured by Shin-Etsu Chemical Co., Ltd.
34-1279 A liquid and 500 g of liquid B are prepared,
Further, 150 g of a glass balloon: Z-27 manufactured by Tokai Kogyo Co., Ltd. is prepared as the glass balloon 14b. The solutions A and B and the glass balloon are mixed into a sealed mixer for about 5 minutes. Then, the rubber in which the glass balloon is uniformly dispersed is defoamed by a vacuum defoaming machine.

On the other hand, a stainless steel shaft constituting the cored bar 12 and a fluororesin tube constituting the release layer 16 are set in a casting apparatus, and the above-mentioned rubber mixed with a degassed glass balloon is poured thereinto. The primary vulcanization is carried out in an oven heated to 150 ° C. for 30 minutes in a mold apparatus. Thereafter, the roller is removed from the casting mold, and
Secondary vulcanization is performed for 4 hours in an oven heated to 00 ° C. to complete the pressure roller 10.

The pressure roller 1 manufactured as described above
0 indicates that the glass balloon 14b is uniformly mixed at a ratio of 15 parts in the non-foamed rubber 14a constituting the elastic layer 14, so that the density is lower than the case where the elastic layer 14 is composed of only the non-foamed rubber. And the specific heat are both low. As a result, the heat capacity per unit volume, which is obtained by multiplying the density and the specific heat, is also reduced. Therefore, while the non-foamed rubber 14a is used for the elastic layer 14, a low heat capacity can be achieved, and the thermal response is improved. Can be achieved. That is, this makes it possible to reduce the warm-up time. Of course, it goes without saying that the effect of low expansion due to heat achieved by using the non-foamed rubber 14a is also achieved.

However, as the glass balloon 14b is mixed, the hardness of the elastic layer 14 increases, which is not preferable. For this reason, there is an optimum range for the mixing ratio of the glass balloon 14b. Hereinafter, the optimum range of the mixing ratio of the glass balloon 14b will be verified.

First, the mixing ratio of the glass balloon 14b was changed to 0 parts (that is, no mixing), 2 parts, 3 parts, 5 parts, 10 parts,
The elastic body samples A to G changed to 15 parts, 20 parts, 25 parts, and 30 parts are hijacked and manufactured by the above-described manufacturing method.
And the density, specific heat, hardness,
The thermal conductivity and the compression set are measured respectively.

Here, the density ρ is defined by measuring the volume (cubic cm) and the mass (g) of each of the samples A to G and calculating from the value calculated by mass 立 volume (g / cubic cm). The specific heat c is a value (J) obtained by measuring each of the samples A to G with a specific heat measuring device.
/ G · K). The hardness is ASKER
Hardness tester (C manufactured by Kobunshi Keiki Co., Ltd .: C
(Type). The thermal conductivity was defined from the value measured by a QTM thermal conductivity meter (manufactured by Kyoto Electronics Industry Co., Ltd.). The compression set is calculated according to JIS K
It was defined from the values measured according to 6301. The measurement results are shown in Table 1 below.

[0031]

[Table 1]

As is evident from Table 1, the density ρ and the specific heat c decrease as the proportion of the glass balloon 14b mixed increases, and as a result, the density ρ × the specific heat c
It can be seen that the heat capacity per unit volume defined by the formula also gradually decreases.

Here, as a comparative example, values corresponding to Table 1 were measured when the pressure roller was composed of a silicone sponge rubber roller. The base rubber of this silicone sponge rubber roller is KE90 manufactured by Shin-Etsu Chemical Co., Ltd.
Using 4FU, 0.6 part of C-24 as a vulcanizing agent, C-
3 and 3.0 parts of KE-P-13 as a foaming agent. The measurement results corresponding to Table 1 in this case are shown in Table 2 below.

[0034]

[Table 2]

Comparison between Table 2 and Table 1 shows that the sample A in which the glass balloon 14b is not mixed, that is,
Density ρ when elastic layer 14 is formed only of non-foamed rubber
× value of specific heat c is 1.510, the value of density ρ × specific heat c when the elastic layer is composed of sponge rubber is 0.7
Compared to 62, the value is extremely high, and it is understood that the thermal response is poor.

On the other hand, it can be understood that if even three parts of the glass balloon 14b are mixed, the value of density ρ × specific heat c is reduced to 1.322, and the thermal responsiveness is improved. Therefore, it has been found that by mixing at least three parts of the glass balloon 14b, the thermal responsiveness is improved as compared with the case where the elastic layer 14 is formed only of the non-foamed rubber.

The evaluation criteria for the physical properties of rubber when used as a pressure roller are as follows. That is, the hardness is
It is preferable that the value of the ASKER C hardness measured under a load of 1 kg is 65 degrees or less corresponding to the non-foamed rubber. This is because if it is higher than 65 degrees, it is too hard and the desired nip width cannot be obtained without elastic deformation at the rolling contact portion with the heating roller.

Although there is no particular standard for the thermal conductivity, a lower thermal conductivity is advantageous because the warm-up time can be further reduced.

The compression set is preferably 20% or less corresponding to the sponge rubber. That is, the compression set is
If it is larger than 20%, a nip mark will be formed on the elastic layer 14 during standby, which leads to a decrease in image quality, which is not preferable.

Taking into account the comparison between the above evaluation criteria and the values in the case of sponge rubber, from Table 1 above, it was found that the mixing ratio of the glass balloon 14b was good up to 25 parts. From this, it has been found that the range satisfying the following equation (1) is optimal in terms of the value of density ρ × specific heat c. 0.77 ≦ ρ · c ≦ 1.32 (1)

Next, on the basis of the above-described verification experiment, various effects in a state where the pressure roller 10 having the elastic layer 14 into which the glass balloon 14b is mixed is actually manufactured and mounted on the fixing device are shown. Verified.

For this reason, the pressure roller 10 having the elastic layer 14 into which 5 parts of the glass balloon 14b are mixed is manufactured, and this is used as Example 1 to manufacture the pressure roller 10 having the elastic layer into which 10 parts are mixed. This was designated as Example 2, and a pressure roller 10 having an elastic layer in which 15 parts were mixed was manufactured and designated as Example 3. Further, as a comparative example, a pressure roller having an elastic layer composed of the above-described sponge roller was manufactured, which was referred to as Comparative Example 1, and a pressure roller having an elastic layer composed of only non-foamed rubber without mixing a glass balloon. This was used as Comparative Example 2.

Here, each pressure roller was incorporated into a fixing device, pressed against the heating roller 22 so that the nip width was 4 mm, and rotated at a peripheral speed of 100 mm / sec.
Then, the state of change in the surface temperature of each pressure roller when the heating roller 22 was heated from room temperature to the fixing temperature was measured over time. Table 3 shows the results.

[0044]

[Table 3]

From Table 3, in order to compare the warm-up time of each pressure roller, the time required for the surface temperature of each pressure roller to reach 130 ° C. was extracted. Show.

[0046]

[Table 4]

As is clear from Table 4, in the case of Comparative Example 2 (a pressure roller having an elastic layer made of only non-foamed rubber), Comparative Example 1 (a pressure roller having an elastic layer made of sponge rubber) was used. ), It takes a considerably longer warm-up time, but in Examples 1 to 3, it was found that there was a remarkable improvement as compared with Comparative Example 2, although not as much as Comparative Example 1. .

Next, the change in the heating shape of each pressure roller was verified. That is, the temperature of the constant temperature heating tank was set to 180 ° C.
Put each pressure roller in an atmosphere of 80 ° C.,
The outer diameters after minutes, 15 minutes and 30 minutes were measured with a laser length measuring machine (manufactured by Tokyo Koden Kogyo Co., Ltd.).

Table 5 shows the measurement results of the pressure roller of Example 1.
Table 6 shows the measurement results of the pressure roller of Example 2, Table 7 shows the measurement results of the pressure roller of Example 3, and Table 8 shows the measurement results of the pressure roller of Comparative Example 1. Table 9 shows the measurement results of the pressure rollers.

[0050]

[Table 5]

[0051]

[Table 6]

[0052]

[Table 7]

[0053]

[Table 8]

[0054]

[Table 9]

FIGS. 4 to 8 show the respective measurement results. From FIG. 4 to FIG. 6 and FIG. 8, in Examples 1 to 3 and Comparative Example 2, the outer diameter shape surely expands by heating, but the change is substantially uniform along the axial direction. Therefore, there is no possibility that paper wrinkles are generated based on the thermal change of the outer diameter shape (outer peripheral surface shape). This is an effect that can be expected naturally since non-foamed rubber is used as the base rubber of the elastic layer 14a.

On the other hand, from FIG. 7 of Comparative Example 1, as described above in the section of the problem to be solved by the invention, as a problem peculiar to sponge rubber, thermal deformation appears randomly along the axial direction. It is understood that this causes paper wrinkles.

Further, when the outer diameter change amount (average value) at each elapsed time is extracted from Tables 5 to 7 and Table 9, the result is as shown in Table 10.

[0058]

[Table 10]

The results shown in Table 10 are shown in FIG. From FIG. 9, it was found that the more the glass balloon was mixed, the smaller the change in outer diameter during heating was, which was preferable.

It is needless to say that the present invention is not limited to the configuration of the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

For example, in the above-described embodiment, the glass balloon is described as being dispersed over the entire area of the elastic layer 14. However, the present invention is not limited to such a configuration, and FIG. As shown in FIG. 11 as a pressure roller 10 'of another embodiment, the elastic layer 14 can have a two-layer structure of a lower layer 14A on the core metal 16 side and an upper layer 14B on the surface layer. In this case, the glass balloon 1
4b only needs to be uniformly dispersed in the non-foamed rubber 14a of the upper layer 14B. In other words, the elastic layer 14
Is formed in the lower layer 14A partially constituting
4b need not be dispersed. The upper layer 14B in which the glass balloon 14b is dispersed as described above.
2 mm is sufficient.

Further, in the above-described embodiment, a glass balloon, that is, a multi-component glass balloon such as aluminosilicate glass or sodium borosilicate glass is used as the low density and low specific heat filler. Is not limited to such a configuration, and for example, a volcanic glass-based shirasu balloon, carbon balloon, resin balloon, metal balloon, or the like can be used. In short, any material may be used as long as the elastic layer 14 has a density and specific heat lower than the heat capacity of the non-foamed rubber 14a itself and has heat resistance.

In the above-described embodiment, the elastic layer of the pressure roller is made of silicone rubber in which glass balloons are dispersed as low-density and low-specific-heat fillers. It is needless to say that the heat capacity can be reduced by using the elastic layer of the heating roller without limitation.

[0064]

As described above in detail, according to the present invention, there is provided a fixing rubber roller capable of securing a nip width and achieving a low heat capacity without using sponge rubber. Will be.

Further, according to the present invention, it is possible to provide a fixing rubber roller which can secure a nip width and does not cause paper wrinkles immediately after the warm-up.

Further, according to the present invention, there is provided a fixing rubber roller capable of securing a nip width and shortening a warm-up time.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a configuration of a fixing device to which a fixing rubber roller according to the present invention is attached.

FIG. 2 is a front sectional view showing a pressure roller as a fixing rubber roller provided in the fixing device shown in FIG.

FIG. 3 is a longitudinal sectional view of the pressure roller shown in FIG.

FIG. 4 is a diagram showing a temporal change state of a heating shape when a pressure roller having an elastic layer into which five parts of a glass balloon are mixed is heated.

FIG. 5 is a diagram showing a temporal change state of a heating shape when a pressure roller having an elastic layer into which 10 parts of a glass balloon are mixed is heated.

FIG. 6 is a diagram showing a temporal change state of a heating shape when a pressure roller having an elastic layer into which 15 parts of a glass balloon are mixed is heated.

FIG. 7 is a diagram illustrating a temporal change state of a heating shape when a pressure roller having an elastic layer made of sponge rubber is heated.

FIG. 8 is a diagram illustrating a temporal change state of a heating shape when a pressing roller having an elastic layer made of only non-foamed rubber is heated.

FIG. 9 is a diagram showing a relationship between a mixing ratio of a glass balloon and a change amount of an outer diameter of a heating roller.

FIG. 10 is a front sectional view showing the configuration of another embodiment of the fixing rubber roller according to the present invention.

11 is a longitudinal sectional view showing a configuration of the fixing rubber roller shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 pressure roller (rubber roller for fixing) 12 core metal 14 elastic layer 14A lower layer 14B upper layer 14a non-foamed rubber 14b glass balloon (low density / low specific heat filler) 16 release layer 20 fixing device 22 heating roller 24 core metal 26 release Layer 28 Heat source

Claims (8)

[Claims] An outer peripheral surface having a predetermined outer diameter, the outer peripheral surface being disposed on an outer periphery of the core bar;
A non-foamed rubber elastic layer adjusted to a predetermined heat capacity per unit volume by mixing a low-density and low-specific-heat filler, and a fixing rubber roller. 2. The fixing rubber roller according to claim 1, wherein a release layer is coated on an outer peripheral surface of the elastic layer. 3. The fixing rubber roller according to claim 2, wherein the release layer is formed of a fluororesin. 4. The fixing rubber roller according to claim 1, wherein the low density and low specific heat filler is a hollow body. 5. The fixing rubber roller according to claim 1, wherein the low-density and low-specific-heat filler contains a multi-component glass. 6. An at least 2 mm from an outer peripheral surface of the elastic layer.
Density ρ (g / cubic cm) and specific heat c in the range up to the depth of
The fixing rubber roller according to claim 1, wherein (J / g · K) is set to satisfy a relationship of 0.77 ≦ ρ · c ≦ 1.32. 7. The fixing rubber roller according to claim 6, wherein a low-density and low-specific-heat filler is not mixed in a range deeper than 2 mm from the outer peripheral surface of the elastic layer. 8. The density ρ (g / cubic cm) and the specific heat c (J / g · K) of the entire elastic layer are set so as to satisfy the following relationship: 0.77 ≦ ρ · c ≦ 1.32. The fixing rubber roller according to claim 1, wherein the fixing rubber roller is set.