JP5072213B2 - 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, copying in an electrophotographic apparatus is performed as follows. That is, first, as shown in FIG. 9, the toner 11 in the toner box is supplied to the surface of the developing roll 14 via the toner supply roll 13, and this toner 11 is further layered with the developing roll 14. It is charged by frictional charging with the blade 15. Then, the charged toner is attached to the electrostatic latent image (original image) formed on the surface of the photosensitive drum 10 to form a toner image, which is passed through the transfer unit 12 to copy paper 16. It is transferred and fixed on top.

  The toner 11 not adhered to the electrostatic latent image and remaining on the surface of the developing roll 14 is scraped off by the toner supply roll 13, collected in the toner box, and reused.

  The toner supply roll 13 is generally composed of a shaft body 1 and a sponge elastic layer 2 made of urethane foam formed on the outer peripheral surface thereof. The sponge elastic layer 2 stably holds the toner 11. In addition to the toner supply performance to be supplied to the developing roll 14, the toner scraping performance for reliably scraping off the toner 11 remaining on the surface of the developing roll 14 is required. That is, if the toner scraping performance is insufficient, the remaining toner remains on the surface of the developing roll 14 and causes toner filming.

  Therefore, in order to improve the toner scraping performance, it is conceivable to set the hardness of the sponge elastic layer 2 high. However, the stress applied to the toner 11 increases, which may cause problems such as deterioration of the toner 11. Yes, not an effective measure.

On the other hand, instead of increasing the hardness of the sponge elastic layer 2, there has been proposed a structure in which a plurality of protrusions extending in the axial direction are provided on the surface thereof at a predetermined pitch (for example, see Patent Document 1).
JP 11-38749 A

  As shown in Patent Document 1, in order to form a plurality of ridges extending in the axial direction on the surface of the sponge elastic layer 2, (1) after forming the sponge elastic layer on the outer peripheral surface of the shaft body, In addition, by forming a plurality of grooves extending in the axial direction by cutting or the like in the circumferential direction at a predetermined pitch, the portion between the adjacent grooves is formed as the above-mentioned ridge, (2) sponge elasticity As a mold for forming the layer 2, two methods are conceivable in which a special one in which grooves corresponding to the above-described protrusions are formed on the inner peripheral surface thereof is used.

  However, in the method (1), since the sponge elastic layer 2 has a low hardness, there is a problem that it is deformed and cannot be processed accurately when cutting or the like is attempted. And if it is going to raise processing accuracy, it will take time and productivity will fall. Further, in the above method (2), not only cost and time are required for manufacturing the mold, but also if the inner peripheral surface of the mold is not polished with high accuracy, the protruding line of the sponge elastic layer 2 is formed in the mold at the time of demolding. Therefore, there is a problem that the burden of polishing work is large.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a toner supply roll that can be obtained without labor and high cost and has excellent toner supply performance and toner scraping performance. .

In order to achieve the above object, the present invention provides a toner supply roll having a shaft body and a sponge elastic layer formed by molding along the outer peripheral surface of the shaft body, the sponge elastic layer being Are formed in a state in which coarse opening recesses having an average opening diameter of 1000 to 3000 μm are scattered, and an average opening is formed between the inner peripheral surfaces of the coarse opening recesses and the coarse opening recesses. A toner supply roll in which a large number of fine opening recesses having a diameter of 150 to 300 μm are distributed and formed is a first gist.

In particular, the present invention provides a second toner supply roll in which the coarse opening recess is formed by transferring the inner peripheral surface of the mold during molding or by laser processing after molding. Among these, a third aspect is a toner supply roll in which the average depth of the coarse opening recess is set to ½ or less of the average opening diameter of the coarse opening recess.

  In the present invention, the above-mentioned “average opening diameter” means that the surface of the sponge elastic layer is observed with an electron microscope, and the opening diameters of coarse opening recesses or fine opening recesses on the surface are measured with respect to any 10 pieces. This is the average of the values obtained. The above “average depth” means that the sponge elastic layer is cut in the thickness direction, the cross section is observed with an electron microscope, and the depth of the coarse opening recesses opened on the surface of the sponge elastic layer is determined for any 10 It is the average value of the measured values.

That is, the present inventors further developed the sponge elastic layer having both the toner supply performance and the toner scraping performance without increasing the hardness of the sponge elastic layer. Repeated research. As a result, the concave openings distributed on the outer peripheral surface of the molded sponge elastic layer are not all aligned with the same or approximate size, but are scattered coarse openings and the inner peripheral surfaces of the open concave sections. When a large number of fine openings distributed between them are mixed, an excellent toner scraping performance can be obtained by the opening edge of the coarse opening, and an excellent toner can be obtained by the large number of fine openings. The present inventors have found that supply performance can be obtained and have reached the present invention.

In the toner supply roll of the present invention, coarse opening recesses having an average opening diameter of 1000 to 3000 μm are dotted on the outer peripheral surface of the die-formed sponge elastic layer, and the inner periphery of the opening recesses of the coarse opening recesses that are scattered. A large number of fine opening recesses having an average opening diameter of 150 to 300 μm are distributed between the surface and the coarse opening recesses . Therefore, an excellent toner scraping performance can be obtained by the opening edges of the coarse opening recesses scattered without increasing the hardness of the sponge elastic layer, and an excellent toner can be obtained by the fine opening recesses distributed in large numbers. Supply performance can be obtained.

As described above, in order to open the coarse opening concave portion and the fine opening concave portion on the outer peripheral surface of the sponge elastic layer in a state of being mixed with each other, on the inner peripheral surface of the sponge elastic layer forming die, In this mold, a sponge elastic layer having a large number of fine foam cells that become fine openings is molded, and the convex part on the inner peripheral surface of the mold is used as the outer periphery of the sponge elastic layer. or transferred to a surface by first molding the sponge elastic layer only is a number distribution forming fine openings recess on its outer peripheral surface, by Rukoto interspersed at predetermined intervals coarse opening recess by laser processing, simple purpose of A toner supply roll can be obtained.

  In the present invention, when the coarse opening recess is shaped by the convex portion formed on the inner peripheral surface of the mold as described above, the convex portion is scattered and the peripheral portion thereof is usually a curve such as a circle, There is no problem such as difficulty in demolding unless the inner peripheral surface of the mold is polished with high accuracy, as in the case of forming the ridges with grooves formed on the inner peripheral surface of the mold, and efficiently. Can be produced. Also, when forming a sponge elastic layer in which two types of large and small foam cells are mixed, it is not necessary to control the shape and distribution state of the foam cells themselves, and production can be performed relatively efficiently.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this embodiment.

  FIG. 1 shows an embodiment of the toner supply roll of the present invention. This toner supply roll includes a shaft body 1 and a sponge elastic layer 2 formed on the outer peripheral surface thereof, and the hardness of the sponge elastic layer 2 is set in a range of 100 to 350 g. And the outer peripheral surface is as shown in FIG. 2 (schematic plan view) and FIG. 3 (schematic sectional view) which expanded the part X enclosed with the chain line in FIG.

  The hardness of the sponge elastic layer 2 is, for example, a value obtained as follows. That is, as shown in FIG. 4A, the toner supply roll is supported by the shaft body 61 at both ends, and the sponge elastic layer 62 is fixed to a jig having a plate-like pressing surface (50 mm × 50 mm, thickness 7 mm). This is a value expressed by a load (g) at a displacement of 1 mm when pressed at a speed of 10 mm / min. However, as shown in FIG. 4 (b), the above-mentioned hardness is measured at a total of 8 measurement points, 2 in the axial direction (width direction) and 4 in every 90 ° in the circumferential direction. Is shown. The larger this value, the higher the hardness of the sponge elastic layer 62, that is, the harder it is.

  On the outer circumferential surface of the sponge elastic layer 2 (returning to FIGS. 2 and 3), coarse opening recesses 3 having large opening diameters are scattered at an appropriate interval, and the gaps between the coarse opening recesses 3 are scattered. A large number of fine opening recesses 4 having a small diameter are formed and distributed.

  The opening of the coarse opening concave portion 3 is a portion that exhibits toner scraping performance by the opening edge portion on the outer peripheral surface of the sponge elastic layer 2, and the average opening diameter is set to 1000 to 3000 μm. That is, if the average opening diameter is out of the above range, the toner scraping performance decreases. The average depth (denoted by D in FIG. 3) from the surface of the coarse opening recess 3 is set to ½ or less of the average opening diameter of the coarse opening recess 3 to achieve excellent toner scraping performance. It is suitable for obtaining. In order to obtain excellent toner supply performance, the interval between the coarse opening recesses 3 (indicated by E in FIG. 2) is set to an interval such that 3 to 8 fine opening recesses 4 are arranged therebetween. Is preferred.

  On the other hand, the opening of the fine opening concave portion 4 is a portion that expresses toner supply performance by accommodating toner in the opening concave portion on the outer peripheral surface of the sponge elastic layer 2 and has an average opening diameter of 150 to 300 μm. Is set. That is, when the average opening diameter is out of the above range, the toner supply performance is deteriorated.

  According to the toner supply roll having the above-described configuration, an excellent toner scraping performance is expressed and distributed in a large number by the opening edges of the coarse opening recesses 3 scattered without increasing the hardness of the sponge elastic layer 2. Excellent toner supply performance can be exhibited by the fine opening recess 4. Therefore, the electrophotographic apparatus equipped with this toner supply roll is free from problems associated with toner supply and scraping, and can maintain excellent image quality for a long period of time.

  Next, the material for forming the toner supply roll of the present invention will be described.

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

  The material for forming the sponge elastic layer 2 may be any material as long as it has been conventionally used for forming the sponge elastic layer 2 of the toner supply roll. A polyurethane foam obtained by combining a polyol component and an isocyanate component used in the production of is preferable.

  Examples of the polyol component include polyolefin polyols such as polyether polyol, polyester polyol, polybutadiene polyol, and polyisobutylene polyol, 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), naphthy Examples include diisocyanate (NDI), xylylene diisocyanate (XDI), 4,4′-diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI, polymethylene polyphenyl isocyanate, and polymeric polyisocyanate. Used together.

  Furthermore, in addition to the polyol component and isocyanate component, if necessary, 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. , Antistatic agents and the like can be appropriately blended.

  The toner supply roll of the present invention can be produced, for example, as follows using the material for forming the shaft body 1 and the sponge elastic layer 2. That is, first, the shaft body 1 is loaded into a predetermined mold as shown in FIG. The mold includes a cylindrical mold 21 having a length substantially equal to the axial length of the sponge elastic layer 2 (see FIG. 1) of the toner supply roll, and caps 22 that close both ends of the cylindrical mold 21. When the mold is clamped, the shaft 1 is supported coaxially with the cylindrical mold 21 by the cap 22, and a molding cavity 23 is formed in the cylindrical mold 21 to give the final roll shape of the target toner supply roll. It has become.

  Then, on the inner peripheral surface of the cylindrical mold 21, a coarse opening is formed in the outer peripheral surface of the sponge elastic layer 2 as shown in FIG. 6 (schematic cross-sectional view) in which a portion Y surrounded by a chain line in FIG. 5 is enlarged. Convex portions 30 for shaping the concave portion 3 (see FIG. 3) are projected at predetermined intervals.

Then, after the material for forming the sponge elastic layer 2 (polyurethane foam composition or the like) is injected into the molding cavity 23 of the mold and foamed and cured, the sponge elastic layer 2 is integrally formed around the shaft body 1. Demold. On the outer peripheral surface of the sponge elastic layer 2 of the toner supply roll obtained in this manner, the coarse opening concave portions 3 formed by the convex portions 30 provided on the cylindrical mold 21 side are formed in a dotted state. A large number of fine opening recesses 4 made of foam cells are distributed between the inner peripheral surface of the coarse opening recesses 3 and the coarse opening recesses 3 .

  In the formation of the sponge elastic layer 2 in the mold, when the expansion ratio is set to about 5 to 20, the average opening diameter of the fine opening recesses 4 opened on the surface of the sponge elastic layer 2 is 150 to 300 μm. It can be formed in the range.

  In addition, the foam cell that becomes the fine opening recess 4 may be a closed cell, an open cell, or a mixture of them, but each foam cell may have appropriate connectivity. For example, after the demolding, when the toner supply roll is rotated around the shaft body 1 and a high-pressure gas (gas such as air or nitrogen) is sprayed onto the sponge elastic layer 2 using a nozzle or the like, The gas diffuses into the sponge elastic layer 2 due to the resistance of the shaft 1, and the walls between the foamed cells and the foamed cells can be partially broken and communicated. The degree of communication can be adjusted by changing the pressure of the injected gas.

  In the above manufacturing method, the sponge elastic layer 2 is not formed directly on the shaft body 1, but is formed via at least one other elastic layer 40 (one layer in FIG. 6) as shown in FIG. It may be. In that case, using the forming material for forming the other elastic layer 40 on the shaft body 1, as in the case of forming the sponge elastic layer 2, the outer periphery of the shaft body 1 is formed using a mold. After the other elastic layer 40 is integrally formed, the shaft body 1 with the elastic layer 40 is loaded into a forming die (see FIG. 5) for forming the sponge elastic layer 2 and is placed on the outer periphery of the elastic layer 40. The sponge elastic layer 2 can be integrally formed. Of course, the other elastic layer 40 is cut into a cylindrical shape from an existing sponge molded body, and this is integrated with the shaft body 1 so that the sponge elastic layer 2 is integrally formed on the outer periphery thereof. Also good.

  Moreover, the coarse opening recessed part 3 formed in the outer peripheral surface of the sponge elastic layer 2 does not shape the convex part 30 provided in the inner peripheral surface of the cylindrical mold 21 as in the above-described manufacturing method, but the fine opening recessed part 4. Alternatively, the sponge elastic layer 2 in which only a large number of distributions are formed may be prepared first, and the coarse opening recesses 3 may be scattered at predetermined intervals on the outer peripheral surface thereof by laser processing or the like.

  Further, the coarse opening recess 3 formed on the outer peripheral surface of the sponge elastic layer 2 may be formed simultaneously with the fine opening recess 4 by the foamed cell. In this case, by adjusting the type and composition of each material in the material composition for forming the sponge elastic layer 2, the coarse opening recess 3 and the fine opening recess 4 that are set to a specific size are simultaneously formed into the sponge elastic layer. It can form so that it may open in 2 outer peripheral surfaces. In this case, it is preferable to adjust the cell diameter distribution of the foamed cells obtained by foaming to a distribution as shown in FIG. 8, for example.

Next, examples of the present invention will be described together with comparative examples.
[Example 1]
Using the following shaft body and sponge composition for forming a sponge elastic layer, a toner supply roll having specific coarse opening recesses and fine opening recesses formed on the outer peripheral surface of the sponge elastic layer according to the following procedure (FIG. 2 and FIG. (See FIG. 3). In order to give a coarse opening recess to the outer peripheral surface of the sponge elastic layer, the inner peripheral surface of the mold for forming the sponge elastic layer is etched to form hemispherical convex portions having a diameter of 1500 μm on an average of 20 to ² per cm ^2. It formed at random so that it might become 40 pieces.

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

<Sponge composition of sponge elastic layer>
90 parts by weight of polyether polyol (Mitsui Chemicals, EP-828, OH number = 28), 10 parts by weight of polymer polyol (Mitsui Chemicals, POP-31-28, OH number = 28), 2 parts by weight of diethanolamine, Silicon foam stabilizer (manufactured by Nihon Unicar Co., Ltd., L-5309) 3 parts by weight, water 2 parts by weight, tertiary amine catalyst (Kao Co., Ltd., Kaulizer No. 31) 0.5 part by weight, tertiary amine catalyst ( Tosoh Corporation, Toyocat HX-35) 0.1 parts by weight, DBTDL 0.1 parts by weight, and isocyanate (Sumitomo Bayer Urethane Co., Ltd., Sumijoule VT-80, NCO% = 45) 30.5 parts by weight Thus, a sponge composition for forming a sponge elastic layer was prepared.

<Production of toner supply roll>
The shaft is coaxially set on the molding die, the die is clamped, 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. By × 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, coarse opening recesses having an average opening diameter of 1500 μm are randomly arranged (ie, scattered) at an average rate of 20 to 40 per 1 cm ² . And between the coarse opening recessed part and the coarse opening recessed part, many fine opening recessed parts obtained by foaming hardening at the time of sponge elastic layer shaping | molding are distributed. In addition, the average opening diameter of the said fine opening recessed part was 200 micrometers.

[Comparative Example 1]
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. Other than that, it was the same as in Example 1 above.

[Examples 2 to 5, Comparative Examples 2 to 5]
By changing the composition of the sponge composition in Example 1 and the shape of the protrusions formed on the inner peripheral surface of the mold, it is formed on the outer peripheral surface of the sponge elastic layer as shown in Tables 1 and 2 below. The average opening diameter of the coarse opening recess and the average opening diameter of the fine opening recess were different from those of Example 1.

  The hardness of each of the toner supply rolls of Examples 1 to 5 and Comparative Examples 1 to 5 thus obtained was measured by the method described above (see FIG. 4). Each toner supply roll was incorporated in a toner cartridge, and this toner cut ridge was left in a low-temperature and low-humidity (15 ° C. × 10%) environment for 7 days, then set in a color laser printer and imaged. Then, the toner supply performance was evaluated by visually evaluating whether or not the initial copy image has uneven density. Further, the toner scraping performance was also evaluated by visually evaluating whether or not the initial copy image had a defect such as a ghost. In addition, all the said evaluation was made into three grade evaluation of favorable ... (circle), some defect ... (triangle | delta), and defect ... x. The used toner had an average particle size of 7 to 10 μm. These results are shown in Tables 1 and 2 below.

  From the results of Tables 1 and 2, the toner supply rolls of Examples 1 to 5 are superior in both toner supply performance and toner scraping performance as compared with the toner supply rolls of Comparative Examples 1 to 5. I understand that.

FIG. 3 is a schematic explanatory view showing an embodiment of a toner supply roll of the present invention. It is a principal part enlarged plan view of FIG. It is a principal part expanded sectional view of FIG. It is explanatory drawing which shows the method of measuring the hardness of the urethane sponge layer of a toner supply roll, Comprising: (a) is a front view, (b) is a side view. FIG. 6 is a schematic explanatory view showing an example of a mold used for manufacturing the toner supply roll of the present invention. It is a principal part expanded sectional view of the said shaping | molding die. FIG. 6 is a schematic explanatory view showing another embodiment of the toner supply roll of the present invention. FIG. 10 is a diagram showing a cell diameter distribution of a sponge elastic layer in still another embodiment of the toner supply roll of the present invention. 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

2 Sponge elastic layer 3 Coarse opening recess 4 Fine opening recess

Claims (3)

A toner supply roll having a shaft body and a sponge elastic layer formed by molding along the outer peripheral surface of the shaft body, and having an average opening diameter of 1000 to 3000 μm on the outer peripheral surface of the sponge elastic layer. In addition, a large number of fine opening recesses having an average opening diameter of 150 to 300 μm are distributed between the inner peripheral surfaces of the coarse opening recesses and the coarse opening recesses. A toner supply roll which is formed. The toner supply roll according to claim 1, wherein the coarse opening recess is formed by transfer of the inner peripheral surface of the mold during molding or laser processing after molding. 3. The toner supply roll according to claim 1, wherein an average depth of the coarse opening recess is set to ½ or less of an average opening diameter of the coarse opening recess.

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