JPH1195541A - Developer carrying roller and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain such a roller having low hardness that a developer permeating into the roller is easily moved and diffused and that carrying property of a developer is improved by controlling the average roughness of the surface of an elastic layer comprising a formed body to <= a specified value. SOLUTION: First, a roller having an elastic layer 3 comprising a formed body around a shaft 2 is inserted under pressure into a cylindrical member having a smaller inner diameter than the outer diameter of the roller. Which the roller is inserted into the cylindrical member, the cylindrical member is heated. After heating, the member is cooled and the roller is taken out from the cylindrical member to obtain a developer carrying roller 1'. In the developer carrying roller 1', it is required that the average surface roughness of the elastic layer 3 is <=50 μm. If the average surface roughness exceeds 50 μm, it is not preferable because enough nip width inbetween a developer carrying body such as a developing roller is not obtd., or the foamed body on the surface is scraped and mixed as a foreign matter in the developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer transport roller and a method of manufacturing the same, and more particularly, to a developer transport roller used in an electrophotographic apparatus such as a copying machine or a printer, an electrostatic recording apparatus, or the like. The present invention relates to a good developer transport roller and a method for efficiently manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the progress of electrophotographic technology, attempts have been made to improve the image quality of various electrophotographic devices such as copiers and printers and electrostatic recording devices by improving a developer. ing. Also, photosensitive drums and belts, paper, overhead projectors (OH
P), a developer is supplied onto an image forming body such as photographic paper, and a developer carrying roller disposed in a developing device for forming a visible image on the surface of the image forming body needs to be improved. Have been. By the way, as a developing method for supplying a developer onto a latent image holding member such as a photosensitive drum holding an electrostatic latent image and attaching the developer to the electrostatic latent image to visualize the electrostatic latent image, generally, (1) a powder cloud method in which developer particles are used in a spray state, (2) a contact development method in which developer particles are brought into contact with a latent image surface of a photosensitive drum and developed,
(3) a jumping development method in which the developer particles are charged and developed by the electric field of the electrostatic latent image without contacting the latent image surface of the photosensitive drum; and (4) a conductive developer having magnetism is electrostatically charged. There are known methods such as a magnetite method in which development is performed by contacting a latent image surface.

[0003] Here, the transport of the developer will be briefly described. For example, the developer filled in the developing device is supplied to the surface of a developer carrier such as a developing roller by a developer transport roller. The developer is arranged in a uniform thin film by the blade, and in this state, the developer is rotated while contacting or approaching the photosensitive drum, so that the developer adheres from the developer to the electrostatic latent image on the photosensitive drum. Thus, the latent image is visualized. Various characteristics are required for the developer transport roller used in the developing device, and in particular, the developer entering the roller is easily moved and diffused, and
It is required that the roller maintain a low hardness and that the supply of the developer to the developer carrier is sufficient, that is, the roller has good developer transportability. However, no conventional developer conveying roller can sufficiently satisfy all of these required characteristics.

[0004]

SUMMARY OF THE INVENTION Under such circumstances, the present invention is directed to a developer in which the developer entering the roller is liable to move and diffuse, and the roller has a low hardness and good developer transportability. It is an object to provide a transport roller.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a developer transport roller having excellent performance as described above, and as a result, have found that the average roughness of the surface of the elastic layer made of foam is reduced. It has been found that the object can be achieved by adjusting the thickness to 50 μm or less. Further, such a developer transport roller can be easily obtained by pressing a roller having an elastic layer made of a foam into a cylindrical member, heating the cylindrical member, and compressing the elastic layer. Was also found. The present invention has been completed based on such findings. That is, according to the present invention, in a developer transport roller that has an elastic layer made of a foam and holds and transports the developer on the surface of the elastic layer, the average surface roughness of the elastic layer is 50 μm or less. And a developer conveying roller characterized by the following. Further, the developer transport roller presses a roller having an elastic layer made of a foam into a cylindrical member, and then heats the cylindrical member to compress the elastic layer and reduce the average surface roughness to 50 μm. It can be manufactured by the following.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The developer conveying roller of the present invention has an elastic layer made of a foam on the outer periphery of a shaft, and the shaft is not particularly limited. However, in the case of a resin shaft, conductivity may be imparted according to the purpose. There is no particular limitation on the foam, for example,
Thermoplastic foams such as polyethylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, viscose, and ionomer, and thermosetting foams such as polyurethane, rubber, epoxy resin, phenol / urea resin, pyranyl resin, silicone resin, and acrylic resin. Of these, polyurethane foam is particularly preferred. As the cell form of the elastic layer, any form such as closed cell or open cell can be used, but open cell is preferable because the dimensional change due to temperature is small. When the material of the elastic layer is a polyurethane foam, the polyol component is not particularly limited, and any hydrophobic or hydrophilic polyol can be used. From the viewpoint of toner fusion, polyester polyol or polyether polyol is used. Is preferred. On the other hand, the isocyanate component is not particularly limited, and a conventionally known one can be used.

As described above, the polyurethane foam is preferably an open-cell polyurethane foam. In particular, a foam obtained by substantially removing the foamed film covering the skeleton between the rollers by, for example, a heat treatment or an alkali treatment is applied to the inside of the roller. This facilitates the movement and diffusion of the developer, which is preferable. Also,
As a roller, various properties can be given to the elastic layer. For example, as a conductive material for imparting conductivity, conductive carbon such as Ketjen Black EC, acetylene black, SAF, ISAF, HAF, FEF,
Rubber carbon such as GPF, SRF, FT, MT, etc., carbon for color (ink) subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, Examples thereof include metal oxides such as nickel, copper, silver, and germanium, and conductive polymers such as polyaniline, polypyrrole, and polyacetylene. Among these, carbon black is low in value and easily controls conductivity in a small amount. The amount of these conductive materials to be blended is usually preferably 0.5 to 50 parts by weight, particularly preferably 1 to 30 parts by weight, based on 100 parts by weight of the elastic layer material.

Further, an ion conductive substance can be used as the conductive material. Examples of the ionic conductive material include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, and tridecylmethyldihydroxyethylammonium perchlorate and lauryltrimethylammonium perchlorate. , Modified aliphatic dimethylethylammonium ethosulfate, N, N-bis (2-hydroxyethyl) -N- (3'-dodecyloxy-2'-hydroxypropyl) methylammonium ethosulfate, 3-laurylamidopropyl-trimethylammonium Methyl sulfate, stearylamidopropyldimethyl-β-hydroxyethyl-ammonium-dihydrogenphosphate, tetrabutylammonium borofluorate, stearylammonium acetate, Organic ionic conductive substances such as quaternary ammonium perchlorates, sulfates, ethosulfate salts, methylsulfate salts, phosphates, borofluoride salts, and acetates such as lauryl ammonium acetate, and charge transfer complexes. Can be The amount of these conductive materials is preferably in the range of 0.0001 to 50 parts by weight based on 100 parts by weight of the material of the elastic layer.

In the developer conveying roller of the present invention, the elastic layer needs to have an average surface roughness of 50 μm or less. If the average surface roughness exceeds 50 μm, there is a possibility that a sufficient nip width with a developer carrier such as a developing roller cannot be secured, or that the foam on the surface is peeled off and becomes foreign matter in the developer. It is not preferable in terms of things.
Particularly preferred average surface roughness is in the range of 30 μm or less. The average surface roughness was determined by enlarging the surface of the elastic layer 100 times with a video microscope (manufactured by Meishinki Koki Co., VMS-1000) and observing one rotation in a circumferential direction with a width of 3 mm. This is a value obtained by averaging the maximum difference between the uneven portions at three places. The hardness (Asker F hardness) of the roller is preferably 60 ° or less, and particularly preferably in the range of 30 to 50 °. If the hardness exceeds 60 °, the transportability of the developer is undesirably reduced. The Asker F hardness refers to a cylindrical ASKER with a needle shape of 25.2 mm in diameter.
A value obtained by measuring with an F hardness tester. Further, the cells near the elastic layer surface preferably have a shape compressed in the radial direction of the roller. By compressing the cells near the surface of the elastic layer as described above, the developer is prevented from being clogged on the surface, and the transportability of the developer is improved. FIG.
FIG. 1 is a schematic cross-sectional view illustrating an example of a developer conveying roller of the present invention. I have. From this figure, it can be seen that the cells near the elastic layer surface have a shape compressed in the radial direction of the roller. In addition,
The radial direction in the present invention is a direction indicated by an arrow in FIG.

The method for producing the developer conveying roller is not particularly limited as long as the roller having the above-mentioned properties can be obtained, and is extremely efficient according to the method of the present invention described below. be able to. The method of the present invention will be described with reference to the accompanying drawings. FIG. 2 is an explanatory diagram showing an example of a method of manufacturing a developer conveying roller of the present invention. In the method of the present invention, first, the roller 1 having the elastic layer 3 made of a foam on the outer periphery of the shaft 2 shown in FIG. It is press-fitted into a cylindrical member 4 having a small inner diameter. Note that an adhesive layer may be provided between the shaft 2 and the elastic layer 3 as necessary. Further, here, the elastic layer 3 is illustrated in the form of a roller in advance. However, in some cases, the elastic layer 3 may have a polygonal shape obtained by cutting a block of foam. The cylindrical member is not particularly limited, and may be a pipe made of metal, resin, or the like. The elastic layer is thermally compressed by heating the shaft 2 and the cylindrical member 4 as described later. Therefore, metals such as aluminum, copper, and iron having good thermal conductivity are preferable, and the inner surface may be coated with a fluorine-based material or the like so as to be easily press-fitted.

The inner diameter of the cylindrical member 4 is not particularly limited, and is appropriately selected depending on the degree of compression of the elastic layer to be inserted, depending on the desired hardness of the roller. The maximum thickness of the elastic layer before compression is 100
In this case, it is preferable to set the thickness of the elastic layer after compression to about 50 to 95. Further, the press-fitting means is not particularly limited, and a known method can be used. Next, as shown in FIG. 2C, the cylindrical member 4 is heated while the roller 1 is inserted into the cylindrical member 4. Here, the heating method is not particularly limited, and a known method can be used. Also, the heating temperature is not particularly limited, and is appropriately selected according to the foam material to be used. For example, when the foam is a polyurethane foam, the temperature is preferably in the range of 150 to 250C. Finally, after the heating is completed, after cooling, the roller is taken out from the cylindrical member 4 to obtain the developer transport roller 1 'of the present invention shown in FIG. 1D. FIG. 1 is a sectional view taken along the line AA in FIG. 2D.

[0012]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example An elastic layer (Asker F hardness: 70 °) made of a polyurethane foam (polyol: ester type) having a length of 307 mm and a diameter of 20.1 mm without a foam film on the outer periphery of a shaft having a length of 372 mm and a diameter of 8 mm was used. 80 pieces / inch)
Was produced. This roller has a length of 340
mm, press-fit into an aluminum pipe with an inner diameter of 19.9 mm and heated at 190 ° C. for 30 minutes using a heating furnace.
After cooling at room temperature, the roller was taken out of the pipe to obtain a roller having an outer diameter of 19.5 mm. The obtained roller had an average surface roughness of 35 μm and an Asker F hardness of 50 °. The condition of the surface is near the surface (approximately
2 mm) had a shape compressed in the radial direction of the roller. Next, in order to evaluate the performance of the roller as a developer transport roller, the roller was incorporated into an image forming apparatus and evaluated by an actual machine. As a result, the image was thinner than a roller using urethane foam having a foam film. It was confirmed that the coloration was improved and a sufficient amount of the developer transported was secured.

Comparative Example An elastic layer (Asker F hardness: 70 °) made of a polyurethane foam (polyol: ester type) having a length of 307 mm and a diameter of 19.5 mm without a foam film was formed on the outer periphery of a shaft having a length of 372 mm and a diameter of 8 mm. Number of cells: 80 / inch)
Was produced. In addition, molding to the roller,
The heat compression was not performed using a grinder. The obtained roller had an average surface roughness of 100 μm and an Asker F hardness of 50 °. The surface condition was such that the cells were not compressed and the cell skeleton was standing in the radial direction.
Next, in order to evaluate the performance of this roller as a developer conveying roller, the roller was incorporated into an image forming apparatus and evaluated by an actual machine. As a result, unevenness was observed in the image compared to the example, and the nip width was sufficiently large. It was confirmed that they could not be secured.

[0014]

According to the present invention, an elastic layer made of a foam having a low hardness and a smooth surface is provided, and the developer entering the inside of the roller easily moves and diffuses, and the transportability of the developer is good. A simple developer conveying roller can be easily obtained. The developer conveying roller of the present invention is used for an electrophotographic apparatus such as a copying machine and a printer, an electrostatic recording apparatus, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a developer conveying roller of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a method for manufacturing a developer conveying roller of the present invention.

[Explanation of symbols]

 1: roller before compression 1 ': roller after compression (developer conveying roller of the present invention) 2: shaft 3: elastic layer made of foam 4: cylindrical member

Claims (6)

[Claims] 1. A developer transport roller having an elastic layer made of a foam and holding and transporting a developer on the surface of the elastic layer, wherein the average surface roughness of the elastic layer is 50 μm or less. Characteristic developer transport roller. 2. The developer transport roller according to claim 1, wherein the elastic layer made of a foam is an elastic layer made of a polyurethane foam having substantially no foam film. 3. The developer transport roller according to claim 1, wherein the cells near the surface of the elastic layer have a shape compressed in the radial direction of the roller. 4. When manufacturing a developer transport roller having an elastic layer made of a foam and holding and transporting the developer on the surface of the elastic layer, the roller having the elastic layer made of the foam is formed into a cylindrical shape. A method for manufacturing a developer transport roller, comprising: heating the cylindrical member after press-fitting the member, compressing the elastic layer, and reducing the average surface roughness to 50 μm or less. 5. The method according to claim 4, wherein the elastic layer made of a foam is an elastic layer made of a polyurethane foam having substantially no foamed film. 6. The method according to claim 4, wherein the cells near the surface of the elastic layer after heating the cylindrical member have a shape compressed in the radial direction of the roller.