JP2007250897A - Bond magnet, magnet roll, and development roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bond magnet, a magnet roll, and a development roll which achieve reuse of a sintered magnet. <P>SOLUTION: The magnet roll 14 includes the magnet block 20 composed of bond magnets that contain magnetic powder containing sintered magnet powder made by powdering a sintered magnet, and contains a bonding agent bonding together the magnetic powder. The magnet roll 14 also includes a shaft 18 having the outer peripheral surface to which the magnet block 20 is attached. Specifically, in the magnet roll 14, the magnet block 20 is composed of the bond magnets, which contain the magnetic powder containing sintered magnet powder made by powdering a sintered magnet. This achieves reuse of a sintered magnet by using sintered magnet powder made by powdering a scrapped sintered magnet, etc. , for the bond magnet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bonded magnet, a magnet roll, and a developing roll.

In recent years, from the viewpoints of resource depletion and environmental protection, efforts for reuse (recycling, reuse) have been actively made in various fields.
JP-A-11-154604 Japanese Patent Laid-Open No. 11-133749

  However, sintered magnets are mounted on motors and the like of many electrical appliances, but even if the electrical appliances are collected, most of them are disposed of without being reused. In addition, in the production stage of sintered magnets, many materials (waste materials) that have become out of specification due to, for example, cracks, defects, dimensional deviations, etc., are disposed of without being reused. Therefore, the inventors have repeated research on the reuse of the waste material of such a sintered magnet, and as a result, have newly found a technique suitable for the reuse of the sintered magnet.

  That is, an object of the present invention is to provide a bonded magnet, a magnet roll, and a developing roll in which a sintered magnet is reused.

  The bonded magnet which concerns on this invention contains the magnetic powder containing the sintered magnet powder which pulverized the sintered magnet, and the binder which couple | bonds magnetic powder. In this bonded magnet, the magnetic powder contains sintered magnet powder. Therefore, the sintered magnet can be reused by using the sintered magnet powder obtained by pulverizing the waste material of the sintered magnet for the bond magnet.

  The sintered magnet powder is preferably a reuse material. In this case, a sufficient amount of sintered magnet powder can be easily obtained.

  A magnet roll according to the present invention includes a magnet block constituted by a bonded magnet including a sintered magnetic powder obtained by pulverizing a sintered magnet, and a binder for binding the magnetic powder, and a magnet block on an outer peripheral surface. And a shaft to which is attached.

  In this magnet roll, the magnet block is composed of a bonded magnet, and in this bonded magnet, the magnetic powder contains sintered magnet powder. Therefore, the sintered magnet can be reused by using the sintered magnet powder obtained by pulverizing the waste material of the sintered magnet for the bond magnet.

  The sintered magnet powder is preferably a reuse material. In this case, a sufficient amount of sintered magnet powder can be easily obtained.

  Further, at least one magnet block may be attached to the shaft, and the magnet block may have a substantially fan-shaped cross section. In this case, the degree of freedom in designing the magnetic force pattern is higher than when the magnet block is cylindrical.

  A plurality of magnet blocks may be attached to the shaft, and at least two of the plurality of magnet blocks may have different contents of the sintered magnet powder contained in the magnetic powder. In this case, the magnetic characteristics of each magnet block are adjusted by varying the content of the sintered magnet powder. For example, the content of sintered magnet powder can be reduced in magnet blocks that require high magnetic properties, and the content of sintered magnet powder can be increased in magnet blocks that do not require high magnetic properties. A large amount of sintered magnets can be reused while maintaining the required magnetic properties. That is, by using the magnet roll having the above structure, further effective utilization of sintered magnets such as reuse materials is realized.

  The developing roll according to the present invention includes a magnet block composed of a bonded magnet including a sintered magnetic powder obtained by pulverizing a sintered magnet, and a binder for binding the magnetic powder, and a magnet block on the outer peripheral surface. A magnet roll having a shaft to which the magnet roll is attached, a sleeve for housing the magnet roll, and a flange attached to the end opening of the sleeve.

  In this developing roll, the magnet block of the magnet roll is constituted by a bonded magnet, and in this bonded magnet, the magnetic powder contains sintered magnet powder. Therefore, the sintered magnet can be reused by using the sintered magnet powder obtained by pulverizing the waste material of the sintered magnet for the bond magnet.

  The sintered magnet powder is preferably a reuse material. In this case, a sufficient amount of sintered magnet powder can be easily obtained.

  Further, at least one magnet block may be attached to the shaft, and the magnet block may have a substantially fan-shaped cross section. In this case, the degree of freedom in designing the magnetic force pattern is higher than when the magnet block is cylindrical.

  A plurality of magnet blocks may be attached to the shaft, and at least two of the plurality of magnet blocks may have different contents of the sintered magnet powder contained in the magnetic powder. In this case, the magnetic characteristics of each magnet block are adjusted by varying the content of the sintered magnet powder. For example, the content of sintered magnet powder can be reduced in magnet blocks that require high magnetic properties, and the content of sintered magnet powder can be increased in magnet blocks that do not require high magnetic properties. A large amount of sintered magnets can be reused while maintaining the required magnetic properties. That is, by using the magnet roll having the above structure, further effective utilization of sintered magnets such as reuse materials is realized.

  According to the present invention, a bonded magnet, a magnet roll, and a developing roll in which a sintered magnet is reused are provided.

  Embodiments of a magnet block manufacturing method and its mold according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps. In addition, the present invention is not limited to the following embodiment, and is merely an embodiment.

  FIG. 1 is a schematic perspective view of a developing roll 10 according to an embodiment of the present invention, and FIGS. 2 and 3 are a sectional view taken along line II-II and a sectional view taken along line III-III, respectively, of the developing roll 10 shown in FIG. FIG.

  As shown in FIGS. 1 to 3, the developing roll 10 includes a long cylindrical metal sleeve 12, a magnet roll 14 disposed inside the sleeve 12, and end openings 12 a and 12 b of the sleeve 12. It is comprised with a pair of flange 16A, 16B fixed by fitting.

  Furthermore, the magnet roll 14 includes a round bar-shaped shaft 18 made of a high-strength material such as metal, and five long magnet blocks 20 (20A to 20E) fixed to the outer peripheral surface 18a of the shaft 18. It is configured.

As shown in the cross-sectional view of FIG. 3, each magnet block 20 has a substantially fan-shaped cross section perpendicular to the longitudinal direction. More specifically, the cross-sectional shape of each magnet block 20 has a first arc A ₁ having substantially the same curvature as the curvature of the outer peripheral surface 18 a of the shaft 18, and the same center of curvature and opening as the first arc A _1. a second arc a ₂ is larger curvature radius than the first arc a ₁ has the corner, the first arc a ₁ and the second two lines straight line connecting the corresponding end points of the arc a ₂ The shape is formed by the minutes L ₁ and L ₂ . A curved surface in which the first arc A ₁ extends in the longitudinal direction of the magnet block 20 is an inner peripheral curved surface 20 a of the magnet block 20, and the second arc A ₂ also extends in the longitudinal direction of the magnet block 20. The curved surface is the outer peripheral curved surface 20b of the magnet block 20, and a pair of planes in which the _two line segments L ₁ and L ₂ extend in the longitudinal direction of the magnet block 20 are both side planes 20c and 20d of the magnet block 20. It has become.

  The polarities on the outer peripheral curved surface 20b of each of the magnet blocks 20A to 20E are as indicated by reference numerals N and S in FIG. That is, the magnet blocks 20 </ b> A to 20 </ b> E are arranged on the outer peripheral curved surface 20 b so that the magnet block 20 </ b> A serves as the N pole and the S pole and the N pole appear alternately in the positive rotation direction of the sleeve 12. The N pole magnet block 20A functions as a pumping pole, the S pole magnet block 20B functions as a layer regulating pole, the N pole magnet block 20C functions as a developing pole, and the S pole magnet block 20D collects. The N pole magnet block 20E functions as a separation pole.

And each magnet block 20 is being fixed to the outer peripheral surface 18a of the shaft 18 by the adhesive agent which is not shown in figure in the inner peripheral curved surface 20a. Since the magnet roll 14 includes a plurality of magnet blocks 20 as described above, the degree of freedom in designing the magnetic force pattern is higher than when a cylindrical magnet block is used. Incidentally, both the first opening angle of the arc A ₁ of each magnet block 20 cross section also has a 60-degree, five magnet block 20A~20E is fixed so as to be adjacent to each other. That is, the shaft 18 is not completely surrounded by the magnet block 20, and the block missing portion 22 where the magnet block 20 does not exist is formed around the shaft 18.

  A gap having a predetermined distance d is formed between the outer peripheral surface 14 a of the magnet roll 14 formed by the outer peripheral curved surface 20 b of the magnet block 20 and the inner peripheral surface 12 c of the sleeve 12.

In addition, the shape and magnetic force of each magnet block 20 can be appropriately changed according to the required magnetic flux density and magnetization pattern. For example, with respect to the shape of the magnet block 20, the first opening angle of the arc A ₁ of the cross section of the magnet block 20 is not limited to 60 degrees, can be increased or decreased for each magnet block as required.

  The magnet roll 14 described above is disposed in the sleeve 12 and is rotatably supported by a pair of flanges 16A and 16B located at both ends of the sleeve 12. Here, the flange 16A and the flange 16B are formed with holes 24A and 24B, respectively, along the central axis thereof. Bearings 26A and 26B (rotatingly supporting the shaft 18 are provided inside the holes 24A and 24B, respectively. For example, a sintered oil-impregnated bearing is attached.

  Next, the constituent material of the magnet block 20 (20A to 20E) described above will be described.

  Among the magnet blocks 20, the magnet block 20 </ b> C that functions as a developing electrode is a rubber magnet or a plastic magnet, and is mainly composed of magnetic powder such as ferrite or Nd—Fe—B and rubber-based binder or plastic-based binder. It consists of and. Of the magnet block 20, the magnet blocks 20A, 20B, 20D, and 20E other than the magnet block 20C are rubber magnets, and are mainly composed of magnetic powder and a rubber-based binder. That is, each of the magnet blocks 20 included in the magnet roll is composed of a plastic magnet or a rubber magnet bonded magnet.

  Here, the magnetic powder of the magnet blocks 20A, 20B, 20D, and 20E that are rubber magnets will be described in more detail.

  This magnetic powder is composed of a new material that is generally used (that is, a material that is not a reuse material or a recycling material) and a sintered magnet powder that is a reuse material. The sintered magnet powder to be used is, for example, a sintered magnet such as a waste material produced in the manufacturing stage of a ferrite sintered magnet or a waste material recovered by use, a predetermined particle size (for example, It is pulverized to a few tens of microns). This sintered magnet powder is kneaded with the above-mentioned new material or binder, and used for production of a magnet block.

  Here, “reuse material” means the reuse of other products or the reuse of defective products or scraps generated in the production process of other products. It is clearly distinguished from “recycled materials” which means the reuse of defective products and scraps generated in

  Note that the amount of recycled materials is limited because they are scraps and collected items generated by the product itself. On the other hand, reuse materials are abundant because many reused products of other products can be used. Therefore, a sufficient amount of sintered magnet powder can be easily obtained by using a reuse material as the sintered magnet powder. In particular, sintered ferrite magnets are used in large amounts, and therefore a large recovery amount is expected. In addition, because of the extremely stable structure, the magnet composition and the alteration of the structure are not a problem. Ferrite sintered magnets are usually required to have as high magnetic properties as possible, making it difficult to use recycled materials as ferrite sintered magnets again. This is because necessary magnetic characteristics cannot be obtained or even if it is obtained, the cost is very high. Taking these situations into consideration, it can be said that using a ferrite sintered magnet as the sintered magnet powder of the present invention is extremely useful.

  As described above, in the magnet roll 14, the magnet block 20 is configured by a rubber magnet (that is, a bonded magnet), and in this rubber magnet, the magnetic powder includes sintered magnet powder that is a reuse material. It is. Since this sintered magnet powder is obtained by pulverizing a waste material of a sintered magnet and pulverizing it, the magnet roll 14 can realize reuse of the sintered magnet.

  In place of the magnet block 20C corresponding to the development pole described above, a magnet block 20F having a structure shown in FIG. 4 may be employed. The magnet block 20 </ b> F is composed of two members, a first block piece 21 and a second block piece 23. The first block piece 21 has the same substantially fan-shaped cross section as the magnet block 20C, and a groove 21a is formed at the center of the outer peripheral curved surface 20b. The groove 21a has a rectangular cross section and is formed over the entire length of the magnet block 20F along the extending direction of the magnet block 20F. The second block piece 23 has substantially the same shape and substantially the same size as the groove 21a formed in the first block piece 21, and is entirely embedded in the groove 21a.

  And the 2nd block piece 23 is comprised with the new material with a high magnetic characteristic. Thereby, the magnetic characteristics of the entire magnet block 20F are at a level that satisfies the required characteristics. On the other hand, the 1st block piece 21 is comprised with the magnetic powder containing sintered magnet powder. That is, even if the development pole magnet block is difficult to use a sintered magnet because it originally has high magnetic properties, by combining the first and second block pieces 21 and 23 described above, In the developing pole magnet block 20F, the sintered magnet can be reused, and the cost of the entire magnet block 20F can be reduced. That is, by employing the magnet block 20F instead of the magnet block 20C, further reuse of the sintered magnet and cost reduction can be realized while maintaining the magnetic characteristics required for the development pole.

  In addition, the content rate of the sintered magnet powder of the reuse material contained in magnetic powder may be made to correspond in each magnet block 20, and may differ in the range of 10 to 100% suitably for every magnet block 20, for example. . In general, since the new material is superior in magnetic properties compared to the sintered magnet powder of the reuse material, the magnetic properties such as the magnetic force of the magnet block 20 are increased by reducing the content of the sintered magnet powder. On the contrary, since the sintered magnet powder of the reuse material is lower in cost than the new material, the production cost of the magnet block 20 can be reduced by increasing the content of the sintered magnet powder. In other words, by adjusting the content of the sintered magnet powder in the magnetic powder according to the function of the magnet block 20, the balance between the magnetic properties and the manufacturing cost of the magnet roll 14 as a whole is realized at a high level. be able to.

  Here, the magnetic characteristics required for each magnet block 20 of the magnet roll 14 will be described with reference to FIGS.

FIG. 5A is a view showing a conventional magnet roll R having the same form as the magnet roll 14 according to the above embodiment, and the five magnet blocks B _{1 to} B ₅ are a magnet block 20C and a magnet block. 20D, magnet block 20E, magnet block 20A, and magnet block 20B, respectively. FIG. 5B shows a magnetic force pattern M of the magnet roll R, and the magnetic pole peaks P _{1 to} P ₅ correspond to the magnet blocks B _{1 to} B ₅ , respectively. Symbols D _{1 to} D ₅ in FIG. 5B indicate lower limit values of magnetic characteristics (that is, magnetic force) required for the magnetic pole peaks P _{1 to} P ₅ .

In the magnet roll R shown in FIG. 5, the magnet blocks B _{1 to} B ₅ are all made of a new material. Therefore, all of these magnet blocks B _{1 to} B ₅ have high magnetic characteristics, and each of the magnet blocks B _{1 to} B ₅ greatly exceeds the lower limit values D _{1 to} D ₅ of the required magnetic characteristics. It has a strong magnetic pattern.

FIG. 6A is a view showing a magnet roll R1 similar to the magnet roll 14 according to the above-described embodiment, and five magnet blocks B _{1 to} B ₅ are a magnet block 20C, a magnet block 20D, a magnet block 20E, It corresponds to the magnet block 20A and the magnet block 20B, respectively. FIG. 6B shows a magnetic pattern M1 (solid line) of the magnet roll R1 and a magnetic pattern M (broken line) for comparison.

Of the magnet blocks B _{1 to} B ₅ of the magnet roll R ₁ , the magnet block B ₂ is made of magnetic powder including sintered magnet powder of reuse material, and the other magnet blocks B ₁ , B _{3 to} B ₅ are Consists of new materials. Magnet block _{B 2,} specifically, the magnetic powder 90 wt%, is composed of a proportion of the binder (NBR) 10 wt%, the sintered magnet powder content of at the magnetic powder is in the 80 wt%.

The magnetic force pattern M1 of the magnet roll R1 is such that the magnetic pole peaks P ₁ , P _{3 to} P ₅ corresponding to the magnet blocks B ₁ , B _{3 to} B ₅ made of a new material have their lower limit values D ₁ , D It is beyond the ₃ ~D _5. Then, with respect to the magnetic pole peak P ₂ of the magnet blocks B ₂ composed of a magnetic powder comprising a sintered magnet powder reuse material, has to exceed the lower limit value D _2. Specifically, although the magnetic pole peak P ₂ is reduced by about 30% compared to the case of the magnet block using the new material, the other magnetic pole peaks P including the magnetic pole peak P ₁ corresponding to the developing pole are included. ₃ to P ₅ in rather substantial effect, no effect on the product properties.

7 (a) is a view showing a magnet roll 14 similar magnet roll R2 according to the embodiment, five magnet block _B 1 .about.B ₅ is magnet block 20C, magnet block 20D, magnet block 20E, It corresponds to the magnet block 20A and the magnet block 20B, respectively. FIG. 7B shows a magnetic pattern M2 (solid line) of the magnet roll R2 and a magnetic pattern M (broken line) for comparison.

Among the magnet blocks B _{1 to} B ₅ of the magnet roll R ₂ , the magnet block B ₂ , the magnet block B _3, and the magnet block B ₅ are composed of magnetic powder containing sintered magnet powder of reuse material, and other magnets. Blocks B ₁ and B ₄ are made of a new material. Specifically, the magnet block B ₂ and the magnet block B ₅ are composed of 90 wt% magnetic powder and 10 wt% binder (NBR), and the content of sintered magnet powder in the magnetic powder is 80 wt%. It has become. Magnet block _{B 3} is specifically, the magnetic powder 90 wt%, is composed of a proportion of the binder (NBR) 10 wt%, the sintered magnet powder content is has a 50 wt% in the magnetic powder.

In the magnetic force pattern M2 of the magnet roll R2, the magnetic pole peaks P ₁ and P ₄ corresponding to the magnet blocks B ₁ and B ₄ made of a new material naturally exceed the lower limit values D ₁ and D ₄ . And also regarding the magnetic pole peaks P ₂ , P ₃ , P ₅ of the magnetic blocks B ₂ , B ₃ , B ₅ made of magnetic powder including sintered magnet powder of reuse material, the lower limit values D ₂ , D ₃ , It has become a thing of more than D _5. Specifically, the magnetic pole peaks P ₂ and P ₅ are reduced by about 30% compared to the case of the magnet block using the new material, and the magnetic pole peak P ₃ is compared to the case of the magnet block using the new material. Although it is reduced by about 20%, the magnetic pole peak P ₁ and the magnetic pole peak P ₅ corresponding to the developing pole are not substantially affected and do not affect the product characteristics.

FIG. 8A is a view showing a magnet roll R3 similar to the magnet roll 14 according to the embodiment, and the five magnet blocks B _{1 to} B ₅ are a magnet block 20F, a magnet block 20D, a magnet block 20E, It corresponds to the magnet block 20A and the magnet block 20B, respectively. FIG. 8B shows a magnetic pattern M3 (solid line) of the magnet roll R3 and a magnetic pattern M (broken line) for comparison.

The magnet block B ₁ corresponding to the developing pole includes a grooved block piece (corresponding to the first block piece 21 described above) and a block piece embedded in the groove (corresponding to the second block piece 23 described above). The block pieces with grooves are made of magnetic powder containing sintered magnet powder of reuse material, and the block pieces embedded in the grooves are made of new material. Specifically, the grooved block piece is composed of 90 wt% magnetic powder and 10 wt% binder (NBR), and the content of sintered magnet powder in the magnetic powder is 80 wt%. . The magnet block _B 2 .about.B ₅ other than the magnet blocks _{B 1} represents is composed of a new material.

Force pattern M3 of the magnet roll R3, the magnetic pole peak _P 2 to P _5, corresponding to the magnet block _B 2 .about.B ₅ composed of a new material, is greater than the lower limit value _D 2 to D ₅ of course. Then, with respect to the magnetic pole peak P ₁ of the magnet block B _1, which is composed of the two block pieces, it has to exceed the lower limit value D _1. Specifically, although the magnetic pole peak P ₁ is slightly decreased (about 5%) as compared with the case of the magnet block composed of only the new material, it does not affect the product characteristics and is at a sufficient level. The magnetic force is maintained. By using ferrite sintered magnets, sintered magnets of metal magnets, bonded magnets, and bonded magnets of ferrite magnetic powder with higher magnetic properties as the constituent material of the block pieces embedded in the grooves, high magnetic properties at the development pole can be obtained. Realized.

  As explained in detail above, the magnet roll employs a plurality of magnet blocks having a substantially sector cross section (not a single cylindrical magnet block), and among these magnet blocks, a magnet corresponding to the developing pole Regarding the block (that is, the magnet block 20C), it is composed of a new material, the content of sintered magnet powder is kept low, or it is composed of first and second block pieces and the second block piece is made of a new material. High magnetic characteristics can be maintained by configuring. On the other hand, the magnet blocks corresponding to other than the developing electrode (that is, the magnet blocks corresponding to the magnet blocks 20A, 20B, 20D, and 20E) are composed of magnetic powder having a high content of sintered magnet powder of reuse material. As a result, the sintered magnet is effectively reused while maintaining the required product characteristics, although there is a certain degree of decrease in magnetic characteristics.

  On the other hand, when one cylindrical magnet block is adopted for the magnet roll, if the magnet block is composed of magnetic powder including sintered magnet powder of reuse material, the content of the sintered magnet powder is determined for the entire magnet block. It must be uniform. In this case, the amount of the sintered magnet powder that can be contained is inevitably determined to be an amount that does not fall below the level (lower limit) of the developing electrode that requires the highest magnetic characteristics, and the utilization efficiency of the sintered magnet powder is reduced. Very bad. This is because, with respect to the magnetic poles other than the developing pole, the required magnetic property level is lower than that of the developing electrode, so even if a large amount of sintered magnet powder is contained, the lower limit value of the required magnetic property is reduced. This is because only the sintered magnet powder of the same amount (content ratio) as that of the developing electrode can be contained, although it can be designed to be sufficiently exceeded.

  That is, in the magnet roll 14, it is composed of a plurality of magnet blocks 20, and the content ratio of the sintered magnet powder can be varied for each magnet block 20, so that the magnetic characteristics of each magnet block are adjusted, More sintered magnet powder can be reused in the magnet roll 14. Further, when the magnet block 20 has a substantially fan-shaped cross section, the magnetic force pattern shape can be easily changed as compared with the case where the magnet block is cylindrical, so that the magnetic force pattern can be designed with a high degree of freedom. can do.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the magnet block is not limited to a fan-shaped cross section, and may be a cylindrical magnet block through which a shaft is inserted. Moreover, it is not necessary to use the bonded magnet in which the sintered magnet powder is contained in all of the plurality of magnet blocks, and an embodiment in which a bonded magnet in which at least one of the sintered magnet powder is contained may be used. Moreover, the bonded magnet of the present invention can be applied to magnets that do not require so high magnetic properties (for example, toy magnets, stationery magnets, sheet magnets, etc.) other than the magnet roll magnet block.

1 is a schematic perspective view of a developing roll according to an embodiment of the present invention. It is the II-II sectional view taken on the line of the image development roll shown in FIG. FIG. 3 is a sectional view of the developing roll shown in FIG. 1 taken along the line III-III. It is the figure which showed the magnet roll in the aspect different from the magnet roll shown in FIG. It is the figure which showed the magnet roll which concerns on a prior art, and its magnetic force pattern. It is the figure which showed the magnet roll equivalent to the magnet roll shown in FIG. 3, and its magnetic force pattern. It is the figure which showed the magnet roll equivalent to the magnet roll shown in FIG. 3, and its magnetic force pattern. It is the figure which showed the magnet roll equivalent to the magnet roll shown in FIG. 4, and its magnetic force pattern.

Explanation of symbols

10 ... developing _{roller, 14, R, R 1 ~R} 3 ... magnet roll, 18 ... shaft, 20,20A～20F ... magnet block.

Claims (10)

Magnetic powder containing sintered magnet powder obtained by pulverizing a sintered magnet;
A bonded magnet comprising a binder for binding the magnetic powder.   The bonded magnet according to claim 1, wherein the sintered magnet powder is a reuse material. A magnetic block including a sintered magnet powder obtained by powdering a sintered magnet, and a magnet block including a bonded magnet including a binder for binding the magnetic powder;
A magnet roll having a shaft to which the magnet block is attached to an outer peripheral surface.   The magnet roll according to claim 3, wherein the sintered magnet powder is a reuse material.   The magnet roll according to claim 3 or 4, wherein at least one magnet block is attached to the shaft, and the magnet block has a substantially fan-shaped cross section.   A plurality of the magnet blocks are attached to the shaft, and at least two of the plurality of magnet blocks have different content ratios of the sintered magnet powder contained in the magnetic powder. The magnet roll as described in any one of these. A magnet block composed of a magnetic powder containing sintered magnet powder obtained by pulverizing a sintered magnet, a bond magnet including a binder that binds the magnetic powder, and a shaft to which the magnet block is attached to an outer peripheral surface. A magnet roll having
A sleeve for accommodating the magnet roll;
A developing roll comprising a flange attached to an end opening of the sleeve.   The developing roll according to claim 7, wherein the sintered magnet powder is a reuse material.   The developing roll according to claim 7 or 8, wherein at least one of the magnet blocks is attached to the shaft, and the magnet block has a substantially fan-shaped cross section. A plurality of the magnet blocks are attached to the shaft, and at least two of the plurality of magnet blocks have different content rates of the sintered magnet powder contained in the magnetic powder. The developing roll according to any one of the above.

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