JP4517920B2 - Toner supply roll - Google Patents

Description

  The present invention relates to a toner supply roll used in electrophotographic apparatuses such as copying machines, printers, and facsimiles.

  In general, for copying in an electrophotographic apparatus, an original image is formed as an electrostatic latent image on the surface of a photosensitive drum D (see FIG. 4), and a toner image is formed by attaching toner to the electrostatic latent image. This is done by transferring and fixing the image onto a copy sheet. As shown in FIG. 4, the toner image is formed on the surface of the developing roll G by supplying toner from the toner box to the surface of the developing roll G as shown in FIG. And the layer forming blade B are charged by frictional charging and then attached to the electrostatic latent image. The remaining toner that is not attached to the electrostatic latent image and remains on the surface of the developing roll G is scraped off by the toner supply roll A ′, returned to the toner box, and then an agitator (stirrer) in the toner box. ) And is reused.

Accordingly, the toner supply roll A ′ is required to have a toner scraping performance for reliably scraping off the toner remaining on the surface of the developing roll G in addition to a toner supplying performance for stably supplying the toner to the developing roll G. . Therefore, the toner supply roll A ′ is generally an elastic roll including the shaft body 1 and a sponge elastic layer 2 ′ formed on the outer peripheral surface thereof. It exhibits supply performance and toner scraping performance (see, for example, Patent Document 1).
JP 2004-45656 A

  However, there is a problem in that toner filming and ghosting occur when an image is output by an actual machine (such as a copying machine). Therefore, as a result of repeated researches on the cause by the present inventors, the cause is that when the charging property of the developing roll G and the toner supply roll A ′ is strong, the toner is supplied from the toner supply roll A ′ to the developing roll G. It was found that the toner was excessively charged in combination with the subsequent triboelectric charging by the layer forming blade B.

  The present invention has been made in view of such knowledge, and an object thereof is to provide a toner supply roll capable of suppressing toner charging.

  In order to achieve the above object, a toner supply roll of the present invention is a toner supply roll having a shaft body and a sponge elastic layer formed along the outer peripheral surface of the shaft body. The composition is made of a sponge composition containing a fluorine-modified polyol.

  The inventors of the present invention have further studied based on the above knowledge in order to suppress the charging that occurs when the toner is supplied from the toner supply roll to the developing roll. As a result of the research, it has been found that when a fluorine-modified polyol is added to the sponge composition of the sponge elastic layer, the frictional force between the toner supply roll and the developing roll is lowered. Moreover, since the sponge composition containing the fluorine-modified polyol has a characteristic that it is easily charged negatively, it has been found that the frictional charging of the toner is further suppressed with respect to the negatively charged toner. Reached.

  In the toner supply roll of the present invention, since the fluorine-modified polyol is blended with the sponge composition of the sponge elastic layer, the frictional force with the developing roll is reduced, and the toner is supplied from the toner supply roll to the developing roll. The charging of the toner can be suppressed by suppressing the charging that occurs at the time. For this reason, even if the subsequent triboelectric charging between the developing roll and the layer forming blade is performed, the toner is not excessively charged, and as a result, neither toner filming nor ghost occurs.

  In particular, when the blending ratio of the fluorine-modified polyol in the sponge composition of the sponge elastic layer is in the range of 0.1 to 30 parts by weight in 100 parts by weight of the polyol component used in the sponge composition, Charging can be more effectively suppressed.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an embodiment of the toner supply roll of the present invention. In this toner supply roll A, a sponge elastic layer 2 is formed on the outer peripheral surface of the shaft 1, and this sponge elastic layer 2 is formed from a sponge composition containing a fluorine-modified polyol.

  Here, the forming material of the shaft body 1 constituting the toner supply roll A of the present invention, the sponge composition of the sponge elastic layer 2, and the like will be described.

  The shaft body 1 may be solid or hollow. Examples of the material for forming the shaft body include metal materials such as iron, stainless steel, and aluminum, polyacetal (POM), acrylonitrile butadiene styrene copolymer (ABS), polycarbonate, and nylon. Such as plastic. And you may apply | coat an adhesive agent, a primer, etc. to the outer peripheral surface of the said shaft body 1 as needed.

  In the sponge composition of the sponge elastic layer 2, a polyol component and an isocyanate component used for producing a flexible polyurethane foam are used, and a fluorine-modified polyol is used for a part of the polyol component. By using this fluorine-modified polyol, the frictional force with the developing roll G (see FIG. 4) can be reduced. As a result, charging that occurs when toner is supplied from the toner supply roll A to the developing roll G can be suppressed, and charging of the toner can be suppressed. From the viewpoint of suppressing charging of the toner, the blending ratio of the fluorine-modified polyol is preferably in the range of 0.1 to 30 parts by weight in 100 parts by weight of the polyol component. Examples of the fluorine-modified polyol include Lumiflon LF200 (manufactured by Asahi Glass Co., Ltd.), Zeffle GK510 (manufactured by Daikin Co., Ltd.), foblin Z-DOL1000 (manufactured by Solvay Solexis), foblin Z-tetraol (manufactured by Solvay Solexis), Examples thereof include MF-100 (manufactured by Gemco), and these are used alone or in combination of two or more.

  Examples of the polyol component include polyether polyol, polyester polyol, polymer polyol and the like, and these are used alone or in combination of two or more. The isocyanate component is not particularly limited as long as it is a polyisocyanate having two or more functions. For example, 2,4- (or 2,6-) tolylene diisocyanate (TDI), orthotoluidine diisocyanate (TODI), naphthylene diisocyanate. (NDI), xylylene diisocyanate (XDI), 4,4'-diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI, polymethylene polyphenyl isocyanate, polymeric polyisocyanate, and the like. These may be used alone or in combination of two or more. Used. If necessary, in addition to the polyol component and the isocyanate component, a crosslinking agent, a foaming agent (water, low-boiling substances, gas bodies, etc.), a surfactant, a catalyst, a flame retardant, a filler, and a conductivity-imparting agent. Further, an antistatic agent or the like may be appropriately blended.

  Next, a method for producing the toner supply roll A will be described. That is, first, a molding die for forming the sponge elastic layer 2 is prepared. Next, an adhesive or the like is applied to the outer peripheral surface of the shaft body 1 as necessary, and this is coaxially installed in the hollow portion of the molding die and sealed, and then the sponge composition of the sponge elastic layer 2 is formed. Inject. Then, foaming and curing is performed to form the sponge elastic layer 2. Thereafter, the mold is removed to obtain the toner supply roll A.

  In the toner supply roll A thus obtained, the outer peripheral surface portion of the sponge elastic layer 2 has most of the cells C forming the sponge elastic layer 2 open to the outside, and the average opening diameter (this average diameter) The opening diameter is an average value of the opening diameters of any 10 cells C, and the opening diameter of each cell C is obtained by measuring the opening diameter at any one position of each cell C by surface observation with an electron microscope. Is not particularly limited, but is usually set in the range of 100 to 800 μm. That is, when the average opening diameter is less than 100 μm, the toner that has entered the cell C tends to be difficult to come out, and when it exceeds 800 μm, the toner conveyance amount tends to decrease, and in any case, the image quality may deteriorate. Because there is. The average cell diameter of the cells C inside the sponge elastic layer 2 (this average cell diameter is an average value of the cell diameters of arbitrary 10 cells C, and the cell diameter of each cell C is determined by the sponge elastic layer 2). Is measured in an electron microscope by measuring the diameter of one arbitrary position of each cell C.) is equal to or larger than the average opening diameter and is set in the range of 100 to 1000 μm. It is preferable. That is, when the average cell diameter is less than 100 μm, the toner tends to be easily clogged in the cell C, and when it exceeds 1000 μm, the amount of toner entering the cell C tends to be too much. This is because there is a risk of deterioration. Further, the inside of the sponge elastic layer 2 can suppress the deterioration of the toner, and the opening 4 having the average opening diameter is formed in all or part of the cell film 3 existing at the boundary between the adjacent cells C. The cell C preferably has an open cell structure in which the cells C are all or partly connected three-dimensionally, but may have a closed cell structure that is not so.

  In addition, the average opening diameter and the average cell diameter of the cell C can be adjusted by changing the expansion ratio when the sponge elastic layer 2 is formed. For example, when the size of the cell C is in the above range (average opening diameter is in the range of 100 to 800 μm, average cell diameter is in the range of 100 to 1000 μm), the expansion ratio is set to about 5 to 20 times.

  Further, as a method of forming the opening 4 in the cell film 3 existing at the boundary portion between the adjacent cells C, in the production of the toner supply roll A, a nozzle or the like is rotated while the toner supply roll A is rotated after demolding. And a method of injecting a high-pressure gas (a gas such as air or nitrogen) onto the sponge elastic layer 2 using the above. As a result, the high-pressure gas diffuses into the sponge elastic layer 2 and the opening action of the cell film 3 is remarkably exhibited. As a result, the opening 4 is formed in the cell film 3 existing at the boundary between adjacent cells C. . The degree of formation of the opening 4 can be adjusted by changing the pressure of the gas to be injected.

  In another embodiment of the toner supply roll of the present invention, as shown in FIG. 2, a cross-sectional view of a surface portion of the sponge elastic layer 2 (a cross-sectional view taken along a plane perpendicular to the axis) of the sponge elastic layer 2 A plurality of ridges (having a rectangular cross-sectional shape) T are formed on the outer peripheral surface at a constant pitch P in the circumferential direction in parallel with the central axis of the roll. Each ridge T is formed to have a substantially uniform height H and a substantially uniform width W, and is continuous from one end edge to the other end edge of the sponge elastic layer 2. The plurality of ridges T improve the toner scraping performance. The rest is the same as the toner supply roll A shown in FIG. 1, and the same reference numerals are given to the same parts.

  The toner supply roll A also has a sponge composition of the sponge elastic layer 2 that is mixed with a fluorine-modified polyol, thereby reducing the frictional force with the developing roll G (see FIG. 4). The charging that occurs when the toner is supplied from the toner supply roll A to the developing roll G can be suppressed, and the charging of the toner can be suppressed.

  As described above, by using the toner supply roll A according to each of the above embodiments, charging is suppressed when toner is supplied from the toner supply roll A to the developing roll G (see FIG. 4). Even if friction charging with the layer forming blade B is performed, the toner is prevented from being overcharged. As a result, toner filming and ghosting are also prevented.

  Next, examples will be described together with comparative examples.

  As described below, a toner supply roll (see FIG. 2) in which ridges were formed on the outer peripheral surface of the sponge elastic layer was prepared using a shaft forming material, a sponge composition of the sponge elastic layer, and the like. For the formation of the sponge elastic layer, a mold having a concave groove corresponding to the ridge was formed on the inner peripheral surface.

[Shaft]
A SUM22 solid cylindrical shaft body having a diameter of 5 mm was prepared.

[Preparation of sponge composition of sponge elastic layer]
Polyether polyol (manufactured by Mitsui Chemicals, EP-828, OH value = 28) 90 parts by weight, polymer polyol (manufactured by Mitsui Chemicals, POP-31-28, OH value = 28), 10 parts by weight, fluorine-modified polyol (Solvay -1 part by weight made by Solexis, foblin Z-DOL1000), 2 parts by weight diethanolamine, 3 parts by weight of silicone foam stabilizer (manufactured by Nippon Unicar Co., Ltd., L-5309), 2 parts by weight water, tertiary amine catalyst (Kao Corporation) KAO.31) 0.5 part by weight, tertiary amine catalyst (Tosoh Corporation, Toyocat HX-35) 0.1 part by weight, DBTDL 0.1 part by weight, and isocyanate (Sumitomo Bayer Urethane Co., Ltd. Joule VT-80, NCO% = 45) 30.5 parts by weight were blended to prepare a sponge composition of a sponge elastic layer.

[Production of toner supply roll]
A shaft body is coaxially set on the molding die and the sponge composition of the sponge elastic layer is filled in the molding space. Then, the molding die is placed in an oven and foamed and cured (60 ° C. × 30 Minutes), a sponge elastic layer (outer diameter 16 mm) was formed on the outer peripheral surface of the shaft body. On the outer peripheral surface of the sponge elastic layer, a plurality of ridges having a rectangular cross-sectional shape were formed at a predetermined pitch P (0.6 mm) in the circumferential direction in parallel with the central axis of the roll. As for the dimensions of each ridge, the width W was 0.4 mm and the height H was 0.2 mm. In addition, each dimension of the said protruding item | line observed the cross section of the toner supply roll with the electron microscope, measured about arbitrary 10 non-isopod trapezoid shapes, and took those average values.

  Using the same sponge composition as in Example 1, a toner supply roll (see FIG. 1) in which no protrusions were formed on the outer peripheral surface of the sponge elastic layer was produced. For forming the sponge elastic layer, a molding die having an inner peripheral surface formed as a mirror surface was used. Other than that, it was the same as in Example 1 above.

  In the sponge composition of the sponge elastic layer of Example 2, the blending ratio of the fluorine-modified polyol was changed to 5 parts by weight. Other than that was carried out similarly to the said Example 2.

[Comparative Example 1]
In the sponge composition of the sponge elastic layer of Example 1, the fluorine-modified polyol was not blended. Other than that, it was the same as in Example 1 above.

[Comparative Example 2]
In the sponge composition of the sponge elastic layer of Example 2, the fluorine-modified polyol was not blended. Other than that was carried out similarly to the said Example 2.

  Using the toner supply rolls of Examples 1 to 3 and Comparative Examples 1 and 2 thus obtained, each characteristic was evaluated according to the following criteria. These results are also shown in Table 1 below.

[Toner charge amount]
Each toner supply roll is incorporated in a developing device of a commercially available printer, and as shown in FIG. 3, after the toner layer 32 is formed on the surface of the developing roll G, the toner in the toner layer 32 is sucked by the suction pump 33, The toner charge amount was measured using a Faraday gauge 34. In the figure, 35 is a filter, 36 is an insulator pipe, 37 is an electrometer, and 38 and 39 are conductors separated from each other.

[Slidability]
An adhesive tape (SPV-A-303S, manufactured by Nitto Co., Ltd.) is attached on a flat plate so that the adhesive surface is on top, and each toner supply roll is placed on the adhesive surface, and then 1N is applied to each toner supply roll. Rolled with horizontal force applied. As a result, when the time required for rolling each toner supply roll to 100 mm is 4 seconds or less, it is difficult to reach the adhesive tape. Those exceeding the thickness were evaluated as x because the friction coefficient was large because they easily attached to the adhesive tape.

[Copy quality]
Each toner supply roll was incorporated into a developing device of a commercially available printer, an image was printed, and the copy image was visually evaluated. As a result, a case where there was no image defect such as a ghost and the image was good was evaluated as ◯, a case where the image defect was minor was evaluated as Δ, and a case where the image defect was difficult to put into practical use was evaluated as ×.

[Durable image quality]
Each toner supply roll was incorporated into a developing device of a commercially available printer, and a character string having a toner density of 5% was output up to 10,000 sheets. Then, the evaluation of the copied image was performed visually. As a result, a case where there was no image defect such as color loss due to toner filming and the image was good was evaluated as ◯, a case where the image defect was minor was evaluated as Δ, and a case where the image defect was difficult to be practically used was evaluated as X.

  From the results of Table 1 above, the toner supply rolls of Examples 1 to 3 are less charged to the toner than the toner supply rolls of Comparative Examples 1 and 2, and image defects due to overcharging are copied. It can be seen that neither an image nor a copy image after endurance has occurred.

  Further, even when MF-100 (manufactured by Gemco) or Fomblin Z-tetraol (manufactured by Solvay Solexis) was used as the fluorine-modified polyol in Examples 1 to 3, the same results as above were obtained.

FIG. 3 is an explanatory diagram (partially enlarged cross-sectional view) schematically showing an embodiment of a toner supply roll of the present invention. FIG. 6 is a cross-sectional view of a surface portion schematically showing another embodiment of the toner supply roll of the present invention. FIG. 6 is an explanatory diagram illustrating a method for measuring a toner charge amount. FIG. 4 is an explanatory diagram schematically illustrating an arrangement state of a toner supply roll, a developing roll, and a photosensitive drum.

Explanation of symbols

1 shaft body 2 sponge elastic layer

Claims (2)

  A toner supply roll having a shaft body and a sponge elastic layer formed along the outer peripheral surface of the shaft body, wherein the sponge elastic layer is made of a sponge composition containing a fluorine-modified polyol. A toner supply roll.   The toner supply roll according to claim 1, wherein the blending ratio of the fluorine-modified polyol in the sponge composition is in the range of 0.1 to 30 parts by weight in 100 parts by weight of the polyol component used in the sponge composition.

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