JP4850562B2 - Roller mold manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a roller mold used for manufacturing a foam roller, and more particularly to a method of manufacturing a roller mold for manufacturing a foam roller having a surface roughness suitable for an image forming apparatus.

Conventionally, a foam roller used in an image forming apparatus such as a developing roller and a transfer roller is generally foamed by casting a foam molding material into a mold composed of a cylindrical member in which a metal shaft is set in advance. It is manufactured by a so-called integral foam molding method in which a foamed elastic layer is formed on the outer peripheral side of the shaft. However, in this method, since a thin film called a skin layer is formed on the surface of the foamed elastic layer, a desired surface roughness cannot be obtained. Therefore, the skin layer has to be removed by polishing.
Therefore, in order to eliminate the polishing operation, a foam molding method using a mold in which a fluororesin coating layer is provided on the inner surface of the cylindrical member has been proposed. Specifically, the inner surface of the cylindrical member is sprayed with fluororesin using an injection nozzle, and a resin coating layer 11A having a large number of irregularities 11a on the surface as shown in FIG. After forming a coating material in which a particulate fluororesin having a different solubility in a solvent from the fluororesin is applied to the fluororesin solution and drying, the particulate fluororesin Only the resin is dissolved to form the resin coating layer 11B in which the unevenness 11b from which the particulate fluororesin 11f is removed is formed as shown in FIG. 3B.
Further, foam molding is performed using the mold in which the coating layers 11A and 11B as described above are formed, so that a large number of holes 52h are formed on the surface on the outer peripheral side of the shaft 51 as shown in FIG. The foam roller 50 including the foamed elastic body 52 can be manufactured (see, for example, Patent Document 1).
JP 2002-326239 A

However, when the resin coating layer is formed by spraying the particulate fluororesin, there is a variation in the blowing of the resin from the injection nozzle, so as shown in FIGS. 4 (a) and 4 (b) A thick portion and a thin portion of the coating layer 11A were formed not only in the longitudinal direction of the inner surface of the member 10 but also in the circumferential direction (in this figure, the thickness of the coating layer is enlarged). The average thickness of the coating layer is about 20 μm, and Rz is about 20 to 30 μm).
Therefore, when the foamed elastic body 52 is foam-molded using the mold made of the cylindrical member 10 as described above, the variation in the holes 52h on the surface of the foamed elastic body 52 shown in FIG. In addition, the variation in the surface cell diameter of the foamed elastic body 52 is increased, and as a result, there is a problem that the toner conveyance amount is not uniform and the image is shaded.

  The present invention has been made in view of conventional problems, and manufactures a foam roller having a foamed elastic body having a uniform surface roughness and having a small variation in surface cell diameter, which is preferably used in an image forming apparatus. An object of the present invention is to provide a method for manufacturing a roller mold that can be used.

According to the first aspect of the present invention, an inner portion of a cylindrical member into which the foam molding material is charged for molding a roller having a foam elastic layer formed by molding the foam molding material on the outer peripheral side of the shaft. A method for producing a roller mold having a coating layer made of a fluororesin on a surface, wherein the nozzle and the cylindrical member are rotated while relatively rotating an injection nozzle for spraying a coating agent containing the fluororesin and the cylindrical member. Are moved relative to each other a plurality of times in the longitudinal direction, and the rotation direction is reversed every movement.
A second aspect of the present invention is the method for manufacturing a roller mold according to the first aspect, wherein the coating agent containing the fluororesin contains a particulate fluororesin.
A third aspect of the present invention is the roller mold manufacturing method according to the second aspect, wherein the particulate fluororesin is polytetrafluoroethylene.
According to a fourth aspect of the present invention, in the roller mold manufacturing method according to any one of the first to third aspects, the variation in the preheating temperature of the cylindrical member is within 10 ° C.

According to the present invention, when manufacturing a roller mold having a coating layer made of a fluororesin on the inner surface of a cylindrical member, the injection nozzle for spraying a particulate fluororesin such as polytetrafluoroethylene (PTFE) and the cylinder While relatively rotating the member, the nozzle and the cylindrical member are relatively moved in the longitudinal direction a plurality of times, and the rotation direction is reversed every time the movement is performed. Variations in the thickness and surface roughness of the coating layer can be reduced. Therefore, by using the roller mold manufactured in this way, a foam roller having a uniform surface roughness suitably used in an image forming apparatus and having a foamed elastic body with little variation in surface cell diameter is manufactured. can do.
At this time, if the variation in the preheating temperature of the cylindrical member is controlled to be within 10 ° C., the variation in the thickness of the coating layer can be further reduced.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
FIG. 1A is a view showing a method for manufacturing a roller mold according to the best mode of the present invention. In this example, the inner surface 10 m of a cylindrical member 10 constituting the mold is formed into a particulate shape using an injection nozzle 20. When spraying the fluororesin, the preheating heating temperature of the cylindrical member 10 is controlled within a range of 60 ° C. ± 2 ° C., and the spray nozzle 20 is moved to one side of the cylindrical member 10 while rotating the cylindrical member 10. It is made to reciprocate from this edge part to the other edge part, and the rotation direction of the said cylindrical member 10 is reversed by an outward path and a return path.
Here, when the inner diameter of the cylindrical member 10 is about 20 mm, the rotational speed of the cylindrical member 10 is in the range of 5 to 1000 rpm and the moving speed (pulling speed) of the injection nozzle 20 is set. 10-2000 mm / sec. It is preferable to set it as the range. The concentration of the fluororesin is preferably 10 to 100%, and the coating amount is preferably 0.1 to 0.5 g / piece.
In this way, when the injection nozzle 20 is reciprocated inside the cylindrical member 10 and the rotation direction of the cylindrical member 10 is reversed between the forward path and the return path, the locus of the injection nozzle 20 is as shown in FIG. As shown in FIG. 1, the scanning directions are crossed between the forward path A and the backward path B. Therefore, as shown in FIG. This is greatly reduced by spraying again with the fluororesin. As a result, as shown in FIGS. 2A and 2B, the coating layer 11 </ b> Z with greatly reduced variations in thickness and surface roughness can be formed on the inner surface 10 m of the cylindrical member 10. Even if the fluororesin is simply layered twice by spraying, it is possible to reduce the thickness variation of the coating layer 11Z as compared with the conventional case. However, as in this example, in the forward path A and the return path B, The improvement effect is remarkable when the rotation direction of the cylindrical member 10 is reversed.
Further, at this time, it is important to control the variation in the preheating temperature of the cylindrical member 10 within 10 ° C., thereby stabilizing the drying property of the fluororesin, and thus the variation in the surface roughness of the coating layer 11Z. Can be further reduced.

In addition, there is no restriction | limiting in particular as a material of the said cylindrical member 10, In addition to metal members, such as iron, aluminum, and stainless steel, engineer plastics, ceramics, etc., such as polycarbonate, polyamide, polyacetal, and polybutylene terephthalate, should be used. I can. Stainless steel is the most suitable from the viewpoint of strength and cost.
In addition, as the fluororesin for forming the coating layer 11Z, polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoroethylene copolymer (FEP), tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene-hexafluoroethylene-perfluoro (alkyl vinyl ether) terpolymer (EPE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene alternating copolymer Examples include coalescence (ETFE) and polyvinyl fluoride (PVF). Polytetrafluoroethylene is particularly preferable from the viewpoint of heat resistance, releasability, stability, chemical resistance, and the like.
Moreover, you may use what mixed the polyimide in these fluororesins.

Next, a method for manufacturing a foam roller using the cylindrical member 10 as a roller mold will be described taking as an example the case where the foam elastic layer is a polyurethane foam.
First, after setting a shaft made of aluminum, stainless steel, or the like in the roller mold, a well-known polyurethane foam molding material such as a polyol component, a polyisocyanate component, a foaming material, or a conductivity imparting agent is placed in the mold. A predetermined amount is cast and foaming is started at a temperature in the range of 20-65 ° C. After the cavity of the mold was filled with polyurethane foam, the temperature was maintained at 70 to 120 ° C. for a predetermined time, and then the mold was removed to form a large number of holes on the outer peripheral side of the shaft. A foam roller having an elastic layer made of polyurethane foam is obtained.
The coating layer 11Z formed on the inner surface of the roller mold manufactured by the manufacturing method of the present example has a surface roughness variation of Rz = 1 to 5 μm and a thickness variation of small. It is possible to obtain a foam roller having a foamed elastic body having a roughness and a small variation in surface cell diameter.

Thus, according to the best mode, when the coating layer 11Z is formed by spraying the particulate fluororesin on the inner surface 10m of the cylindrical member 10 used for the molding of the foam roller, the cylindrical member 10 is formed. As the injection nozzle 20 is reciprocated from one end portion of the cylindrical member 10 to the other end portion while rotating the rotation direction, the rotation direction of the cylindrical member 10 is reversed between the forward path A and the return path B. Variations in the thickness of the coating layer 11Z can be greatly reduced.
At this time, if the variation in the preheating temperature of the cylindrical member 10 is controlled within 10 ° C., the variation in the thickness of the coating layer 11Z can be further reduced.
In the above-described best mode, the cylindrical member 10 is rotated, but the spray nozzle 20 may be rotated.

Examples The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following.
Experiment 1
A cylindrical stainless steel having an inner diameter of 18 mm and a length of 250 mm used for the foam roller mold is preheated to 60 ° C., and the cylindrical nozzle is rotated at a rotational speed of 500 rpm, while the injection nozzle is set to 500 mm / sec. By moving at a pulling speed, the polytetrafluoroethylene having an average particle diameter of 20 μm is applied twice on the inner surface of the cylindrical stainless steel by spraying, dried, and the surface roughness of the coating layer is adjusted. Variation was measured. The coating amount was 0.2 g / piece, and the preheating temperature was controlled in the range of 60 ° C. ± 2 ° C. (temperature variation was 4 ° C.).
When polytetrafluoroethylene was applied twice, the surface roughness variation of the formed coating layer was 3 μm in the case where the rotational direction was reversed between the forward path and the backward path (Example 1). In the case where the rotation directions were the same (Comparative Example 1), the variation in the surface roughness of the coating layer was 10 μm.
Moreover, when the polyurethane foam roller was foam-molded using the roller mold of Example 1, the surface cell diameter of urethane was 150 to 230 μm. On the other hand, when the roller mold of Comparative Example 1 was used, the surface cell diameter of urethane was 50 to 500 μm.
Thereby, it was confirmed that the roller mold manufactured by the manufacturing method of the present invention reduces variations in the surface roughness of the coating layer. Further, by using this roller mold, it is possible to produce a foam roller having a foamed elastic body having a uniform surface roughness suitably used in an image forming apparatus and having a small variation in surface cell diameter. confirmed.

Experiment 2
Next, in order to examine the influence of the variation in the preheating temperature of the cylindrical stainless steel, when the preheating temperature is 60 ° C. ± 2 ° C. and the coating layer is formed (Example 1), the preheating temperature is 60 ° C. ± 6 ° C. As a comparison, a case where a coating layer was formed (Example 2) was compared.
The coating layer was applied twice by spraying, and the rotation direction was reversed between the forward path and the return path.
As a result, in Example 1, the variation in surface roughness was 3 μm. On the other hand, even in Example 2 in which the control range of the preheating temperature was large, it was found that the variation in the surface roughness of the coating layer was 4 μm, which was larger than Example 1, but significantly improved compared to Comparative Example 1 above. .
Moreover, when the polyurethane foam roller was foam-molded using the roller mold of Example 1, the surface cell diameter of urethane was 150 to 210 μm. On the other hand, when the roller mold of Example 2 was used, the surface cell diameter of urethane was 100 to 250 μm, which was slightly larger than that of Example 1, but was significantly improved compared to Comparative Example 1 above. I understood.
Experiment 3 (reference experiment)
Next, in order to examine the influence of the variation in preheating temperature when the rotation direction is the same in the forward path and the return path, when the coating layer is formed with the preheating temperature of cylindrical stainless steel set to 60 ° C. ± 2 ° C. (Comparative Example) 1) was compared with the case where the preheat temperature was 60 ° C. ± 6 ° C. and the coating layer was formed (Comparative Example 2). The coating layer was applied by spraying twice in the same manner as in Experiment 2 above, and the rotation direction was the same in the forward path and the return path.
As a result, in Comparative Example 1, the variation in surface roughness was 10 μm. On the other hand, in Comparative Example 2 in which the control range of the preheating temperature was large, the variation in the surface roughness of the coating layer was 12 μm, which was larger than that in Comparative Example 1.
Moreover, when the polyurethane foam roller was foam-molded using the roller mold of Comparative Example 1, the surface cell diameter of urethane was 50 to 500 μm. On the other hand, when the roller mold of Comparative Example 2 was used, the surface cell diameter of urethane was as large as 1000 μm at the maximum, and the generation of skin was also observed in part.
According to Experiment 2 and Experiment 3, the roller mold manufactured by controlling the preheating temperature within ± 5 ° C. has a small variation in the surface roughness of the coating layer, and the foam manufactured using this roller mold It was confirmed that the roller had a uniform surface cell diameter.

  As described above, according to the present invention, the variation in the thickness of the coating layer 11Z made of the fluororesin formed on the inner surface of the cylindrical member used for the molding of the foam roller can be greatly reduced. It is possible to manufacture a foam roller having a foamed elastic body that has a uniform surface roughness and that has a small variation in surface cell diameter.

It is a figure which shows the manufacturing method of the roller mold which concerns on the best form of this invention. It is a schematic diagram which shows the state of the coating of the roller mold by this invention. It is a figure which shows the manufacturing method of the conventional roller mold. It is a schematic diagram which shows the state of the coating of the conventional roller mold.

Explanation of symbols

10 cylindrical member, 10 m inner surface of cylindrical member, 20 injection nozzle,
11Z coating layer.

Claims (4)

  A roller having a coating layer made of a fluororesin on the inner surface of a cylindrical member into which the foamed molding material is formed for molding a roller having a foamed elastic layer formed by molding a foam molding material on the outer peripheral side of the shaft A method for manufacturing a mold, wherein the nozzle and the cylindrical member are relatively moved in the longitudinal direction a plurality of times while relatively rotating the spray nozzle for spraying a coating agent containing a fluororesin and the cylindrical member. A method for producing a roller mold, characterized in that the rotational direction is reversed every movement.   The method for manufacturing a roller mold according to claim 1, wherein the coating agent containing the fluororesin contains a particulate fluororesin.   The roller mold manufacturing method according to claim 2, wherein the particulate fluororesin is polytetrafluoroethylene. The method for manufacturing a roller mold according to any one of claims 1 to 3, wherein the variation in preheating temperature of the cylindrical member is within 10 ° C.

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