JP2008242239A - Toner supply roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner supply roller that prevents insufficient image density. <P>SOLUTION: When the number of cells that are open in the circumferential face 2a of an elastic layer 2 is 100%, the number of cells having opening diameter of 300 μm or greater is 10% or more, and the number of cells having opening diameter of 100 μm or smaller is 10% or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In an image forming apparatus such as a copying machine or a printer, the present invention supplies toner (developer) to an image forming body such as a photoreceptor or paper and supplies the toner to a developing roller that forms a visible image on the surface. More particularly, the present invention relates to a toner supply roller that is preferably used as a toner supply roller used for the purpose and a method for manufacturing the same, and more particularly to a toner that can optimize toner supply capability and prevent image density deficiency of the visible image.

  In an image forming apparatus using an electrophotographic system such as a copying machine or a printer, a toner (developer) is supplied to an image forming body such as a photoconductor or paper to form a visible image on the surface of the developing roller. To supply the toner, a toner supply roller is used.

  FIG. 1 is a side view showing such a toner supply roller, FIG. 2 is a developed view of the outer peripheral surface of the elastic layer viewed from the outside in the radial direction, and FIG. 3 is a cross-sectional view showing the vicinity of the outer peripheral surface of the elastic layer. The toner supply roller 10 includes a polyurethane elastic layer 2 formed around the shaft 1, and a large number of cells 3 are formed on the outer peripheral surface 2 a of the elastic layer 2. Many cells 4 that do not open to the surface are also formed inside the elastic layer 2, and many of these cells 4 are cells 3 that open to the outer peripheral surface 2 a directly or via other cells 4. Communicate with.

  FIG. 4 is a schematic diagram showing the toner supply roller 10 mounted on the image forming apparatus. The toner supply roller 10 rotates against the developing roller 11 while being pressed against each other and has a predetermined charge. A new toner 12 adjusted to have an amount is pumped up from the hopper 14, and the pumped toner 12 is held on the outer peripheral surface 2 a and is conveyed to the pressing portion 15 that presses the developing roller by the depression allowance δ. While supplying new toner 12 to the roller 11, the old toner 13 is scraped off from the developing roller 11, the scraped toner 13 is held on the outer peripheral surface 2 a and conveyed to the hopper 14 where the old toner 13 is discharged and collected. It works as follows.

  In order to give such a function to the toner supply roller 10, it is necessary to open a large number of cells 3 capable of holding toner on the outer peripheral surface 2 a of the elastic layer 2, In order to increase the amount of storage, a polyurethane cell having a continuous cell structure including a large number of cells 4 communicating with the cells 3 opened on the surface is also used.

In order to form such a toner supply roller 10, the total area of the cells having a size of 100 to 800 μm occupies 20% or more of the total opening area among the cells 3 opening on the outer peripheral surface 2 a of the elastic layer 2. (For example, refer to Patent Document 1).
JP 2000-56556 A

  However, in the above-described prior art, the definition of the cell opening area distribution is too wide (loose). In fact, a visible image is formed by an image forming apparatus equipped with a toner supply roller having an elastic layer having such a cell opening area distribution. However, it is difficult to increase the amount of toner supplied to the developing roller. There was a problem that it could not be surely prevented.

  The present invention has been made in view of such problems, and an object thereof is to provide a toner supply roller that does not cause insufficient image density.

  <1> is an arrangement in which an elastic layer containing a large number of cells opened on the outer peripheral surface is arranged around the shaft, and the toner rotates by pressing the peripheral surfaces against the developing roller provided in the image forming apparatus. In the toner supply roller, the number of cells opening on the outer peripheral surface is 100%, the number of cells having an opening diameter of 300 μm or more is 10% or more, and the number of cells having an opening diameter of 100 μm or less is The toner supply roller is characterized by being 10% or more.

  According to <1>, the number of cells having an opening diameter of 300 μm or more is 10% or more and the opening diameter is 100 μm or less, assuming that the number of cells opening on the outer peripheral surface of the elastic layer is 100%. As described later in detail, a large cell can be surrounded by a rigid wall, which causes the toner supply roller to be pressed against the developing roller. When the outer peripheral surface is compressed and deformed, it is deformed to the back of the cell, so that the toner confined in the back of the cell can be discharged from the cell, increasing the amount of toner supply and insufficient image density. The problem can be solved.

  Embodiments of the present invention will be described with reference to the drawings. As described above with reference to FIG. 1, the toner supply roller 10 includes a polyurethane elastic layer 2 formed around the shaft 1, and FIG. 5 shows an outer peripheral surface of the elastic layer. As shown in the developed view as seen from the outside in the radial direction, a large number of cells 3 are formed on the outer peripheral surface 2a, and the outer periphery is shown in FIG. Many cells 4 that do not open to the surface 2a are also formed in the elastic layer, and many of these cells 3 and 4 are in communication with each other to form a communication cell structure.

In the toner supply roller 10 of the present invention, the total number of cells 3 opened in the outer peripheral surface 2a is 100%, the number of cells having an opening diameter of 300 μm or more is 10% or more, and the diameter of the opening is 100 μm or less. It is characterized by a number of 10% or more. Here, in the present specification, when the shape of the opening of the cell 3 is not circular, the diameter is the longest diameter L _{1 of the} opening (that is, the longest separation distance is provided) as illustrated in FIG. , The distance between the two points P ₁ and P ₂ on the opening edge) and the minor axis L ₂ of the opening (that is, in a direction perpendicular to the direction connecting the two points P ₁ and P ₂ giving the major axis L ₁₎ The distance between the two points Q ₁ and Q ₂ on the opening edge, which is the longest distance between them, is defined as an average value.

  The operation of the surface cell structure as described above will be described below. First, as in the conventional toner supply roller, the distribution of the opening area of the cells opening on the surface is shown in FIG. 7 where the horizontal axis indicates the opening diameter (μm) and the vertical axis indicates the number ratio (%) of the cells. As shown in the graph, when the toner is of a narrow width, most of the toner is accommodated in a cell 93 having a large volume and having an area equal to or larger than the average value of the distribution. In the vicinity thereof, since there is no small cell far from the cell 93, it is surrounded by a thin wall 97 as shown in a sectional view in FIG.

  In this case, as shown in the cross-sectional view of FIG. 8B, the wall 97 is deformed at the portion where the toner supply roller is pressed against the developing roller 11, but the portion is in contact with the developing roller 11 because of its low rigidity. Only is crushed and deformed, and the base of the wall 97 does not change. For this reason, the shape of the bottom of the cell 93 hardly changes, and therefore the toner 20 accommodated in the bottom of the cell 93 is not discharged from the cell 93.

  That is, in order for the toner supply roller to have a sufficient discharge capability, there are a sufficient number of cells both large enough to hold toner and small enough to form a rigid wall. In a toner supply roller with a narrow distribution of the opening area of the cells, there are few cells that are large enough to hold toner, while small enough to form a rigid wall. The number of cells is small, and therefore, the required discharge capacity cannot be carried.

  On the other hand, in the toner supply roller 10 according to the present invention, the distribution of the opening area of the cell opening on the surface is shown in FIG. 9A and FIG. In addition to the large cell 3A having a cell diameter of 300 μm or more, there are many cells 3B having a cell diameter of 100 μm or less, as shown in the graph in which the vertical axis represents the cell number ratio (%). The wall 7 around 3A is thick as shown in the cross-sectional view of FIG. 10A. Therefore, the wall 7 is deformed at the pressing portion 15 where the toner supply roller 10 is pressed against the developing roller 11. Since the rigidity of the wall 7 is high when it is forced to move, not only the portion that contacts the developing roller 11 but also its base deforms, and as a result, the bottom of the cell 3A also greatly deforms and vibrates. The toner 20 contained in the bottom of 3A is the cell 3 It becomes easy to be exhaled.

  Here, a cell having a cell diameter of 300 μm or more can accommodate a large amount of toner. However, when such a cell is less than 10% in the number of cells, the toner supply roller 10 As a result, the capacity of toner on the outer peripheral surface 2a of the toner decreases and the discharge capacity of the toner inevitably decreases. On the other hand, the cell having a diameter of 100 μm or less has a low capacity for storing toner, but has a rigid wall as described above. However, if such a cell 3B is less than 10%, the rigid wall 7 cannot be formed around the large cell 3A. Even in this case, the discharge capability of the toner 20 from the cell 3A cannot be improved.

  In addition, if the number ratio of cells having a cell diameter of 300 μm or more is too large, the probability that cells having a cell diameter of 300 μm or more are close to each other increases, and as a result, the rigidity of the cells having a cell diameter of 100 μm or less is increased. Since the discharge capacity is reduced because it becomes difficult to form a smooth wall, the number ratio of cells having a cell diameter of 300 μm or more is preferably 50% or less, while the number ratio of cells having a cell diameter of 100 μm or less is If it becomes too large, the total volume of the cells opening on the surface cannot be secured sufficiently, and the toner holding capacity is lowered. Therefore, the number ratio of cells having a cell diameter of 100 μm or less is preferably 30% or less. .

  The toner supply roller 10 having the above characteristics can be formed as follows, for example. That is, as shown in a cross-sectional view in FIG. 11, the shaft 1 is disposed in a cylindrical mold 31, and both ends of the mold 31 are closed with caps 32 to form a cavity 33, and then a polyurethane material is injected into the cavity 33 Then, it is foam-cured in the mold. As a material to be injected, a material obtained by stirring and mixing polyol, isocyanate, water, and a catalyst is used.

  Then, when the elastic layer 2 is molded using the mold 31, by using a formulation as shown in the examples described later, the cell opening area as shown in FIG. 9 (a) and FIG. 9 (b) is obtained. An elastic layer having a distribution can be formed.

  A cylindrical mold 31 is used, and the shaft 1 is disposed therein according to the above description, and both ends of the mold 31 are closed with caps 32, and then polyol, isocyanate, water, and catalyst are stirred therein. The mixed materials are injected and foam-cured in a mold to prepare a plurality of types of toner supply roller samples, and Examples 1 to 3 and Comparative Examples 1 to 3 are respectively prepared according to the composition of the injected materials. It was.

  Then, with respect to the toner supply rollers 10 in these examples, these rollers were mounted on the corresponding printers, an image output test was performed, and image density was checked using a Macbeth densitometer to make a determination. Further, for the toner supply roller of each example, the ratio of the number of cells 3 having a diameter of 100 μm or less and the ratio of the number of diameters of 300 μm or more of the cells 3 opened on the outer peripheral surface were calculated, and the toner discharge performance was also measured. Table 1 shows the evaluation results and the formulations used for preparing the samples of each example.

The number ratio of the cells 3 opened to the outer peripheral surface 2a of the toner supply roller 10 in each example is obtained by taking micrographs at 12 randomly selected outer peripheral surfaces for each toner supply roller (magnification 100 times, field of view). Area 20 (μm) ² , image processing of the obtained image, in all these 12 places, calculate the area for each of the cells that open to the outer peripheral surface, the total number, the diameter of 100μm or less, the diameter of 300μm or more The number of cells was calculated and the above-mentioned number ratio was obtained, where the diameter of the opening of the cell was, as described above, the major axis of the opening (that is, the two points on the opening edge where the mutual separation distance was the longest). The distance between the two points on the opening edge, the longest separation distance measured along a direction perpendicular to the direction connecting the two points giving the major axis. Calculated as an average value with the distance) It was.

  In addition, the toner discharge capacity of each example toner supply roller is 50 mm on the flat plate while pressing the toner supply roller of each example with the elastic layer filled with toner against the flat plate with a pressure that gives a recess of 1 mm. In the meantime, the weight of the toner discharged on the flat plate was measured to determine the toner discharge capability.

  The toner supply rollers 10 in these examples are all finished to the same size. The diameter of the shaft was 6 mm, the diameter of the elastic layer 2 was 15 mm, and the length was 260 mm.

  As is apparent from Table 1, the number of cells opened on the outer peripheral surface is assumed to be 100%, the number of cells having an opening diameter of 300 μm or more is 10% or more, and the number of cells having an opening diameter of 100 μm or less is 10 Only when it is at least%, printing with a good image density is possible, and otherwise a good image cannot be obtained. In addition, when the blending ratio of moisture and kaolinizer No1 is increased, the distribution ratio of large cell diameter is increased, while when the blending ratio of kaolinizer No31 is increased, the distribution ratio of small cell diameter is increased. It has been found that there is a tendency to increase, and it has been found that this can be used to control the cell diameter distribution.

*1) 三洋化成工業(株)製, ポリエーテルポリオール
*2) 架橋剤
*3) 東レ・ダウコーニングシリコーン(株)製, シリコーン整泡剤
*4) 花王(株)製, アミン触媒
*5) 花王(株)製, アミン触媒
*6) ＴＤＩ−８０と粗ＴＤＩの混合物中の質量比を示す。なお, ＴＤＩ−８０は, ２,４-トリレンジイソシアネート（Ａ）と２,６-トリレンジイソシアネート（Ｂ）との質量比（Ａ／Ｂ）が80／20の混合物である。
*7) ポリイソシアネート成分系の使用量を指数表示したものである。（ＮＣＯインデックス ＝ （ポリイソシアネート成分系中のＮＣＯのモル数／ポリオール成分系中の水を含めたイソシアネート反応性活性水素基の合計モル数）×100）

* 1) Polyether polyol, manufactured by Sanyo Chemical Industries
* 2) Cross-linking agent
* 3) Silicone foam stabilizer manufactured by Toray Dow Corning Silicone Co., Ltd.
* 4) Made by Kao Corporation, amine catalyst
* 5) Made by Kao Corporation, amine catalyst
* 6) The mass ratio in the mixture of TDI-80 and crude TDI is shown. TDI-80 is a mixture having a mass ratio (A / B) of 2,4-tolylene diisocyanate (A) to 2,6-tolylene diisocyanate (B) of 80/20.
* 7) The amount of polyisocyanate component system used is indicated by an index. (NCO index = (number of moles of NCO in polyisocyanate component system / total number of moles of isocyanate-reactive active hydrogen groups including water in polyol component system) × 100)

It is a side view showing a toner supply roller. FIG. 4 is a development view of an outer peripheral surface of an elastic layer of a toner supply roller as viewed from the outside in the radial direction. FIG. 4 is a cross-sectional view showing the vicinity of the outer peripheral surface of an elastic layer of a toner supply roller. FIG. 4 is a schematic diagram illustrating a toner supply roller that is attached to the image forming apparatus. It is the expanded view which looked at the outer peripheral surface of the elastic layer from the radial direction outer side. It is sectional drawing of the outer peripheral surface vicinity of an elastic layer. 7 is a graph showing a distribution of cell opening diameters in a conventional toner supply roller. FIG. 6 is a cross-sectional view in the vicinity of the outer peripheral surface of an elastic layer, showing a change in shape when an open cell is pressed in a conventional toner supply roller. 6 is a graph showing a distribution of cell opening diameters in the toner supply roller according to the present invention. FIG. 6 is a cross-sectional view in the vicinity of the outer peripheral surface of an elastic layer, showing a change in shape when an open cell is pressed in a toner supply roller according to the present invention. It is sectional drawing which shows the metal mold | die used for forming a toner supply roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 2a The outer peripheral surface of an elastic layer 3 The cell opened to an outer peripheral surface 3 The cell of opening diameter 300 micrometers or more 3 The cell of opening diameter 100 micrometers or less 4 The cell not opening on the surface 7 Wall 10 Toner supply roller 11 Developing roller 12 New toner 13 Old toner 14 Hopper 15 Pressing portion 20 Toner 31 Cylindrical mold 31a Inner peripheral surface of mold 32 Cap 33 Cavity

Claims (1)

Toner supply for supplying toner by rotating around the shaft while pressing the peripheral surfaces against the developing roller provided in the image forming apparatus. In Laura
The number of cells opening in the outer peripheral surface is 100%, the number of cells having an opening diameter of 300 μm or more is 10% or more, and the number of cells having an opening diameter of 100 μm or less is 10% or more. Toner supply roller.

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