JP2007170579A - Manufacturing method for foam roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simply manufacturing a foam roller having low hardness and high durability. <P>SOLUTION: In this manufacturing method for the foam roller 3 constituted by a core metal unit 1 and a cylindrical foam body 2 around it, the foam body 2 is produced by mixing unvulcanized non-foam raw material compound 5 and a non-reaction substance 4 and passing through mixing, molding, foam-vulcanizing, and grinding processes, and the cell diameter of the foam body 2 is smaller than the outside diameter of the non-reaction substance 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a foam roller used as a pressure roller, a fixing roller, a charging roller, a transfer roller or the like in an electrophotographic image forming apparatus.

Foaming rollers such as charging rollers, transfer rollers, pressure rollers, and fixing rollers used in electrophotographic image forming apparatuses are nip widths (nip widths) that are in contact with the oppositely pressed rollers. In order to ensure this, it is required to reduce the hardness of the foam.
However, when the foam has a low hardness, there arises a problem that it is difficult to obtain the shape accuracy of the foam roller in the grinding process. In addition, when the strength of the foam is weakened and the pressure is constantly applied, the foam is deformed with time, so that the durability of the foam roller is low.

Here, an example of a fixing unit in which a foam roller is used will be described with reference to FIG.
The fixing unit includes a pressure roller, a fixing roller, and a heating element that applies heat to the fixing roller. In this case, the pressure roller becomes a foam roller. The surface layer of the pressure roller is deformed by the pressure at the contact portion between the pressure roller and the fixing roller, and a nip portion is formed at the contact portion between the pressure roller and the fixing roller. The unfixed toner on the transfer paper is melted and adhered to the transfer paper by the heat from the nip portion and the fixing roller.
In this process, pressure and heat are applied to the pressure roller, which is a foam roller. Reference numeral 117 denotes transfer paper, 200 denotes a surface layer of the fixing roller, 201 denotes a core metal of the fixing roller, 202 denotes a heating element of the fixing roller, 203 denotes a surface layer of the pressure roller, and 204 denotes a core metal of the pressure roller.

For example, in the technique described in Patent Document 1, a foam is obtained by controlling the cell diameter by extrusion using an unreacted substance. Moreover, the method of making a foam into 2 layer structure is generally known. Use materials with different foaming rates during extrusion. That is, the side close to the metal core is a low foaming rate material, and the side close to the surface is a high foaming material.
The foam obtained by this has high hardness on the side close to the core and low hardness on the side close to the surface. When the foaming roller 3 obtained by this method is brought into contact with the counterpart roller, a wide nip width can be obtained. Further, since the material other than the surface layer has high hardness, the foam is less likely to be deformed over time.
JP 2002-347056 A

However, in the above-described conventional example, since the two-layer extrusion process is performed, there are problems that it takes time for the process, the boundary between the layers is generated, and only the surface layer is crushed (not elastically deformed).
An object of the present invention is to provide a method for producing a foaming roller, which can easily obtain a foaming roller having low hardness and high durability.

In order to achieve the above object, the invention according to claim 1 is a method of manufacturing a foam roller comprising a core metal and a cylindrical foam around the core, wherein the foam is an unvulcanized unfoamed raw material composition. It is produced by mixing a product and an unreacted substance, and kneading, molding, foam vulcanization, and grinding processes, and the cell diameter of the foam is smaller than the outer diameter of the unreacted substance.
According to a second aspect of the present invention, in the method for manufacturing a foaming roller according to the first aspect, the unvulcanized unfoamed raw material composition containing the unreacted substance is formed into a sheet shape and then wound around a cored bar. Features.
A third aspect of the present invention is the method of manufacturing a foaming roller according to the first or second aspect, wherein the core metal can wind the sheet-shaped product of the unvulcanized unfoamed raw material composition more than 10 times. It is characterized by having.

Invention of Claim 4 is the manufacturing method of the foaming roller of Claim 1, 2, or 3 WHEREIN: The thickness of the unvulcanized unfoamed raw material composition whose outer diameter of the said unreacted substance is the said sheet shape x0 Less than .3.
According to a fifth aspect of the present invention, in the method for manufacturing a foam roller according to any one of the first to fourth aspects, the unreacted substance is contained in a sheet-shaped article with respect to the content of the portion close to the cored bar. Thus, the content corresponding to the vicinity of the surface of the foaming roller is large, and the outer diameter of the portion corresponding to the vicinity of the surface of the foaming roller is larger than the outer diameter of the portion close to the core.
A sixth aspect of the present invention is the foaming roller manufacturing method according to any one of the first to fifth aspects, wherein the foam is conductive.

According to the first aspect of the present invention, since the cell diameter of the foam <the outer diameter of the unreacted substance, the unvulcanized unfoamed raw material composition has a space larger than the cell diameter in the foam. . As a result, it is possible to obtain a low hardness foaming roller.
According to the second aspect of the invention, the unvulcanized unfoamed raw material composition 5 containing the unreacted substance is formed into a sheet shape and then wound around the core metal, so that the space due to the unreacted substance is uniformly distributed. Is possible. As a result, it is possible to reduce the hardness variation of the foam roller.
According to the invention described in claim 3, the unvulcanized unfoamed raw material composition is wound around the core metal by 10 or more turns. Thereby, when the foaming roller is viewed in the circumferential direction, the distribution of unreacted substances can be apparently reduced. Therefore, when viewed in the circumferential direction, it is possible to obtain a foaming roller with little hardness variation.

According to invention of Claim 4, it is set as the outer diameter of an unreacted substance <thickness of the unvulcanized unfoamed raw material composition of sheet shape × 0.3. Therefore, when the unvulcanized unfoamed raw material composition is wound around the core metal, the sheet-shaped unvulcanized unfoamed raw material composition can be brought into close contact with each other even if unreacted substances are present. This makes it possible to obtain a foam that does not have air bubbles due to poor adhesion after foam vulcanization.
According to the invention of claim 5, the unreacted substance is near the surface with respect to the content of the portion close to the core metal. Has a large outer diameter. This makes it possible to reduce the hardness near the surface of the foam roller as compared with the foam near the core.
According to the sixth aspect of the present invention, since the foam is conductive in addition to no hardness variation as seen in the circumferential direction, the nip width is uniform and wide. Thereby, a foam roller having uniform conductivity can be obtained.

  Examples of the present invention will be described below. First, the drawings will be described. FIG. 1 is a configuration diagram of a foam roller, FIG. 2 is a characteristic diagram showing the relationship between the number of windings around a cored bar 1 and hardness variation, and FIG. 3 Unreacted material 4 and unvulcanized sheet-like vulcanization when winding a cored bar 4 is a schematic diagram showing the state of the unfoamed raw material composition 5, FIG. 4 is a characteristic diagram showing the content distribution of the unreacted substance 4 in the foam 2, and FIG. 5 shows the relationship between the content distribution of the unreacted substance 4 and the hardness. FIG. 6 is a characteristic diagram showing the outer diameter distribution of the unreacted substance 4 in the foam 2, FIG. 7 is a characteristic chart showing the relationship between the content distribution of the unreacted substance 4 and the hardness, and FIG. 8 is the nip width. It is a characteristic view which shows the relationship between electrical resistance dispersion | variation. FIG. 9 is an overall view of the image forming apparatus. FIG. 10 is a diagram illustrating a process in which a foam roller is used.

As shown in FIG. 1, a foaming roller 3 used as a pressure roller, a fixing roller, a charging roller, a transfer roller or the like in an electrophotographic image forming apparatus is composed of a core metal 1 and a cylindrical foam around it. It consists of two.
The foam 2 is made of an unvulcanized unfoamed raw material composition 5 (FIG. 3) containing a polymer material, a foaming agent, and various additives, and is referred to as kneading, molding, foam vulcanization, and shape processing (for example, external grinding). Made through processing steps.
One method of processing the foam 2 is to use a particulate unreacted material 4 (FIG. 3) that does not react with the unvulcanized unfoamed raw material composition 5. This is a processing method in which an unvulcanized unfoamed raw material composition 5 and an unreacted substance 4 are mixed, a foam 2 is formed through kneading, molding, foam vulcanization, and external grinding, and then the unreacted substance 4 is removed.
The present invention is characterized by a method for manufacturing a foam roller in which an unvulcanized unfoamed raw material composition 5 and an unreacted material 4 are mixed, formed into a sheet shape, and wound around a cored bar 1. By appropriately setting the outer diameter, quantity, distribution, and thickness of the sheet-shaped material of the unreacted substance 4, the surface layer of the foam roller 3 has a low hardness, and the vicinity of the core metal 1 has a low hardness. Making it possible.

Embodiments of the method for producing a foam roller according to the present invention will be described below. In addition, it processed by the following 1) -6) as common conditions of each Example.
1) Unvulcanized unfoamed raw material composition 5
Unreacted material 4: Sodium chloride compound Polymer material: Ethylene propylene rubber (EPDM)
Foaming agent: Organic foaming agent ADCA system Crosslinking agent: Sulfur In addition, a vulcanization accelerator, a bulking agent, and a softening agent were also blended.
2) Core 1: Material SUM22, outer diameter φ6mm, length 300mm
3) Dimensions of foam roller 3; outer diameter φ80 mm, length 270 mm
4) Foam 2
Average cell diameter: 100 μm
Average number of cells: 50 cells / mm ² (The foam was cut and the number of cells of a certain area was counted)
5) Foam vulcanization: Heat treatment was performed at 160 ° C. for 20 minutes using a hot air furnace.
6) Removal of unreacted substance 4: After foam vulcanization, the foam is immersed in water to dissolve and remove unreacted substance 4

<Example 1>
The unreacted material 4 was mixed with the unvulcanized unfoamed raw material composition 5, adhered to the metal core 1, and foamed vulcanized and externally ground. As a method for adhering to the cored bar 1, a crosshead method was used using an extruder. Two types of unreacted substance 4 having an outer diameter of φ50 μm and φ300 μm were used. Moreover, the thing which does not contain the unreacted substance 4 was also created. Each sample hardness was measured using an Asker C hardness meter.
<Result>
Unreacted material 4: 30 degrees Unreacted material 4φ50 μm: 28 degrees Unreacted material 4φ300 μm: 24 degrees From this result, it can be seen that the foaming roller 3 with low hardness can be obtained by the manufacturing method of the present invention. Further, running was performed using the image forming apparatus shown in FIG. 9 until the foam 2 was broken.
<Result>
No unreacted substance 4: 303,000 sheets Unreacted substance 4φ 50 μm: 305,000 sheets Unreacted substance 4φ 300 μm: 304,000 sheets From this result, the foam 2 is low in the production method of the present invention. Although it is hardness, it turns out that durability equivalent to the foaming roller 3 of high hardness is acquired.
In the case of “cell diameter in foam 2> outer diameter of unreacted substance 4 in foam 2”, the hardness of foam 2 does not decrease. Therefore, the low altitude required by the present invention cannot be obtained.
Then, in the image forming process, the width of the nip portion, which is a contact portion with the roller pressed against each other, becomes small, and a normal image cannot be obtained.

<Example 2>
Unreacted unfoamed raw material composition 5 was mixed with unreacted substance 4 having an outer diameter of 300 μm and adhered to cored bar 1, and foam vulcanization and outer diameter grinding were performed. As a method of attaching to the core 1,
a) Adhering to the cored bar 1 by a crosshead method using an extruder b) Forming into a 1500 μm-thick sheet shape and then attaching the cored bar 1 by winding it 10 times. The shaft and circumferential hardness variations of the produced foam roller 3 were measured using an Asker C hardness meter.
<Result>
Method a): 20 ° to 28 ° Method b): 22 ° to 26 ° The crosshead method has a larger variation. This is presumably because the distribution variation of the unreacted substance 4 in the unvulcanized unfoamed raw material composition 5 increases due to the pressure and heating generated during the extrusion process.
From this result, it can be seen that the foaming roller 3 with less hardness variation can be obtained by mixing the unreacted material 4 with the unvulcanized unfoamed raw material composition 5 and winding it around the cored bar 1.

<Example 3>
The unreacted material 4 was mixed with the unvulcanized unfoamed raw material composition 5 and formed into a sheet shape, and then wound around the core 1 to perform foam vulcanization and outer diameter grinding. The outer diameter of the unreacted material 4 was φ150 μm. In this example, the number of times the sheet-shaped unvulcanized unfoamed raw material composition 5 was wound around the core metal 1 was changed, and a plurality of foam rollers 3 were manufactured.
In order to make the outer diameter after winding the same, the thickness of the sheet-shaped article was changed according to the number of windings. When winding 10 times, it was 1500 micrometers. Since the expansion ratio of the unvulcanized unfoamed raw material composition 5 does not depend on the thickness of the sheet-shaped product, the thickness becomes 3000 μm if it is wound five times.
The hardness of the foaming roller 3 was measured at 36 locations in the circumferential direction, and the hardness maximum value−the hardness minimum value was defined as the hardness variation amount. The results of the number of windings and the amount of variation in hardness are shown in FIG. From this result, it can be seen that when the number of windings is small, the hardness variation in the circumferential direction increases.
The reason is considered as follows. The distribution variation of the unreacted substance 4 in the unvulcanized unfoamed raw material composition 5 in the form of a sheet inevitably occurs. Therefore, if the number of windings is small, the distribution variation becomes the hardness variation. Conversely, if the number of windings is increased, the unreacted substance 4 is apparently reduced in distribution variation. Therefore, it can be seen that the foaming roller 3 having a small hardness variation in the circumferential direction can be obtained if the number of windings is 10 or more.

<Example 4>
Unreacted unfoamed raw material composition 5 was mixed with unreacted substance 4 having an outer diameter of 300 μm, formed into a sheet shape, wound around core metal 1 15 times, and subjected to foam vulcanization and outer diameter grinding. Processing was performed by changing the thickness of the sheet-shaped article. As an evaluation method, the number of bubbles 6 (FIG. 3) in the foam 2 due to the fact that the sheets did not adhere to each other when wound around the core 1 as shown in FIG. 3 was measured.

Thickness of sheet-shaped object Number of bubbles 6 100 μm (30 μm) 30
500 μm (150 μm) 25
700 μm (210 μm) 10
1000 μm (300 μm) 0
1500 μm (450 μm) 0
The value in parentheses is the value of the sheet shape thickness x 0.3. From this result, if the outer diameter of the unreacted substance 4 <the thickness of the sheet-shaped unvulcanized unfoamed raw material composition 5 x 0.3, the core metal The foaming pressure roller 3 in which bubbles 6 are not generated when the sheet-shaped unvulcanized unfoamed raw material composition 5 is wound around 1 can be obtained.
In the case of “the outer diameter of the unreacted substance 4> the thickness of the unvulcanized foam raw material composition × 0.3”, a gap is formed around the unreacted substance 4 when wound. In the case of the foam roller 3, hardness variation occurs due to the gap. When the hardness variation occurs, in the image forming process, a variation in the width of the nip portion that is a contact portion with the roller pressed against each other occurs, and a normal image cannot be obtained.

<Example 5>
The unreacted unfoamed raw material composition 5 was mixed with the unreacted material 4 and formed into a sheet having a thickness of 1500 μm, and then wound around the core 1 to perform foam vulcanization and outer diameter grinding. The outer diameter of the unreacted material 4 was φ300 μm.
In this processing, when the unvulcanized unfoamed raw material composition 5 is mixed with the unreacted substance 4 to form a sheet, the portion corresponding to the portion close to the core metal 1 has a small content and corresponds to the portion close to the surface. In the part, the content was increased. The state of the content is shown in FIG. Moreover, the hardness measurement result of the foaming roller 3 is shown in FIG.
In this way, the content of the unreacted substance 4 is small in the portion close to the core metal 1 and increased in the vicinity of the surface, so that the portion near the core metal 1 has high hardness and the surface near the surface has low hardness. Can be obtained.

<Example 6>
The unreacted unfoamed raw material composition 5 was mixed with the unreacted material 4 and formed into a sheet having a thickness of 1500 μm, and then wound around the core 1 to perform foam vulcanization and outer diameter grinding. When the unreacted material 4 is mixed with the unvulcanized unfoamed raw material composition 5, the outer diameter is reduced at a location corresponding to a location close to the core 1 and the outer diameter is increased at a location corresponding to a location close to the surface. (See FIG. 6). The content was 100 / mm ^{3 in} all cases. The hardness measurement result of the foaming roller 3 produced in this way is shown in FIG. FIG. 7 shows a change in hardness of the foaming roller 3 in the radial direction.
From this result, the outer diameter of the unreacted material 4 is small in the portion close to the core metal 1 and large in the vicinity of the surface, so that the portion near the core metal 1 has high hardness and the surface near the surface has low hardness. Obtainable.

<Example 7>
In Example 6 above, carbon was contained in the unvulcanized unfoamed raw material composition 5. The hardness of the processed foam roller 3 near the surface is 23 degrees, and the portion close to the core is 29 degrees. Since carbon was contained, the hardness was higher than that of the sample of Example 6.
On the other hand, as a comparison, the uncured unfoamed raw material composition 5 having a blending amount in which the hardness of the foaming roller 3 is 23 degrees was processed by a normal crosshead method. In this case, the hardness of the entire region of the foam 2 is 23 degrees.
In the two foam rollers 3, the nip width was varied by changing the pressure pressed against the other roller by a resistance measuring machine (not shown), and the electrical resistance variation in the circumferential direction was measured. The result is shown in FIG. The foaming roller 3 of the present invention has less variation in electrical resistance. The reason for this is that since the entire foam body has a low hardness, the entire foam body 2 is deformed by the pressure applied to the opposing roller, and the dispersion state of the contained carbon is greatly changed.
From this result, it can be seen that when the same nip width is obtained, the manufacturing method of the present invention can obtain the foaming roller 3 with less variation in electric resistance.

It is a block diagram of a foaming roller. It is a characteristic view which shows the relationship between the frequency | count of winding to a metal core, and hardness dispersion | variation. It is a schematic diagram which shows the state of an unreacted substance and a sheet-like unvulcanized unfoamed raw material composition at the time of winding a metal core. It is a characteristic view which shows content distribution of the unreacted substance in a foam. It is a characteristic view which shows the relationship between content distribution of an unreacted substance, and hardness. It is a characteristic view which shows the outer diameter distribution of the unreacted substance in a foam. It is a characteristic view which shows the relationship between content distribution of an unreacted substance, and hardness. It is a characteristic view which shows the relationship between nip width | variety and electrical resistance dispersion | variation. 1 is an overall view of an image forming apparatus. It is a figure explaining the process in which a foaming roller is used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal core 2 Foam 3 Foam roller 4 Unreacted substance 5 Unvulcanized unfoamed raw material composition 6 Bubble 100 Pressure roller 101 Fixing roller 102 Paper discharge roller 103 Follower roller 104 Photoconductor 105 Transfer roller 106 Cleaning blade 107 Brush roller 108 Charging roller 109 Developing roller 110 Toner replenishing roller 111 Stirrer plate 112 Toner tank 113 Toner 114 Waste toner tank 115 Equipment exterior 116 Feed roller 117 Transfer paper 200 Fixing roller surface layer 201 Fixing roller core 202 Heating element 203 of the fixing roller Pressure roller surface layer 204 Pressure roller cored bar

Claims (6)

  In the method for producing a foaming roller comprising a cored bar and a cylindrical foam around the core, the foam is prepared by mixing an unvulcanized unfoamed raw material composition and an unreacted material, kneading, molding, foam vulcanization. A method for producing a foaming roller, wherein the foaming cell is produced through a grinding process, and the cell diameter of the foam is smaller than the outer diameter of the unreacted substance.   2. The method for producing a foam roller according to claim 1, wherein the unvulcanized unfoamed raw material composition containing the unreacted substance is formed into a sheet shape and then wound around a cored bar. .   The method for manufacturing a foam roller according to claim 1 or 2, wherein the core metal has a configuration capable of winding a sheet-shaped product of the unvulcanized unfoamed raw material composition more than 10 times. A method for manufacturing a foam roller.   In the manufacturing method of the foaming roller of Claim 1, 2, or 3, The outer diameter of the said unreacted substance is smaller than the thickness x0.3 of the said sheet-shaped unvulcanized unfoamed raw material composition, A method for manufacturing a foam roller.   5. The method of manufacturing a foaming roller according to claim 1, wherein the unreacted substance corresponds to the vicinity of the surface of the foaming roller with respect to the content of the portion close to the core in the sheet-shaped article. A method for producing a foaming roller, characterized in that the content of the foaming roller is large at a location where the outer diameter is close to the surface of the foaming roller, and the outer diameter is large at a location corresponding to the vicinity of the surface of the foaming roller.   The method for manufacturing a foaming roller according to any one of claims 1 to 5, wherein the foam is conductive.

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