JPH1145001A - Magnet roller, production thereof, developing roller using the magnet roller, and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent image. SOLUTION: This magnet roller in which a magnet main body part and a shaft part are integrally molded is molded with a bond magnet composition mixed with Sr ferrite having the Sr/Ba ratio of 1-100. The difference between the magnetic poles having maximum and minimum magnetic forces of the magnet roller is defined as >=100 G. At the time of executing molding, the magnet main body part is thrust by an ejecting pin to be removed from a mold. A gate is provided in a metallic mold, so as to correspond to the outer periphery or end face part of the magnet main body part or the outer peripheral part of the shaft part and the bond magnet composition is injected through the gate. This developing roller is composed of the magnet roller or roller obtained by this method. and a sleeve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine or a printer, an electrostatic recording apparatus, or the like, and a photosensitive drum or belt holding an electrostatic latent image, paper, OHP, photographic paper, or the like. Roller, which is used as a developing roller for supplying a developer to an image forming body such as a toner to form a visible image on the surface of the image forming body, a method of manufacturing the magnet roller, and a magnet roller and a sleeve. More specifically, with respect to the developing roller and the developing device using the developing roller, it is possible to obtain a magnet roller that can easily increase the magnetic force at low cost and a magnet roller that is excellent in dimensional accuracy by reducing man-hours. The present invention relates to a method for manufacturing a magnet roller, a developing roller using the magnet roller, and a developing device.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus, a developing method for visualizing an electrostatic latent image on a latent image holding member such as a photosensitive drum is known. A so-called jumping in which a magnet roller formed by a bonded magnet is provided in a rotating sleeve as a roller, and a magnetic developer (toner) carried on the surface of the sleeve flies onto the latent image holding member by a magnetic force characteristic of the magnet roller. There has been known a developing method of supplying toner to the surface of a latent image holding member by a phenomenon to visualize an electrostatic latent image.

Heretofore, the above magnet roller has been conventionally injection-molded using a mold in which a magnetic field is arranged and a pellet-like bonded magnet composition in which a magnetic powder such as ferrite is mixed with a binder of a thermoplastic resin such as nylon or polypropylene. It is manufactured by molding or extruding to form a roller and magnetizing it to desired magnetic properties. In this case, usually, a shaft portion for supporting the roller is provided at both ends of the roller, but the shaft portion at both ends or one end is integrated with the roller body to reduce the manufacturing cost and increase the magnetic force. It has been proposed to form a bonded magnet composition.

However, the conventional magnet roller in which the shaft portion at both ends or one end portion is formed integrally with the roller body portion from the bonded magnet composition has the following disadvantages. (1) With the recent development of electrophotographic technology, the quality of images has been improved. In this case, in order to obtain a higher quality image, it is necessary to further increase the magnetic force of a specific magnetic pole (for example, a developing pole) among the performances of the magnet roller, but ferrite powder is used as the magnetic powder. In the conventional magnet roller formed of the bonded magnet composition, even the magnetic pole having the highest magnetic force has a limit of about 1000G,
There is a limit to the magnetic force generated by the magnet roller on the sleeve surface. (2) In general, it is conceivable to increase the amount of added magnetic powder in order to develop a high magnetic force. However, the fluidity of the bonded magnet composition at the time of forming the magnet roller is extremely reduced, and the In such cases, the obtained magnet body and shaft are not sufficiently filled with resin, and the surface cannot transfer the mold surface accurately, resulting in reduced dimensional accuracy. Unfilled areas may occur. (3) When the shaft portions at both ends or one end are formed integrally with the roller body with the bonded magnet composition, the contact area with the mold is increased, so that it is difficult to take out the magnet roller from the mold. There are cases where the number of steps is increased and the dimensional accuracy of the magnet roller is deviated when the mold is removed.

A conventional developing roller comprising the above-mentioned magnet roller and a sleeve rotatably disposed along the outer periphery of the developing roller, if used for a long period of time, transports the developer, blade or developer in the developing device. Rubbing of the roller causes abrasion on the surface thereof, which may cause troubles such as a function of transporting and charging the developer and an image defect called ghost in an image depending on the type of the developer. Furthermore, in order to improve the functions such as developer conveyance and charging to obtain a high-quality image, fine irregularities having an appropriate roughness may be provided on the sleeve surface. There is a drawback that the state of the minute unevenness changes, and a high quality image cannot be obtained. Such wear problems can occur with any sleeve made of any material,
This is particularly noticeable when the sleeve is formed from an aluminum alloy which is a relatively soft metal.

Therefore, recently, in order to improve the wear resistance of the sleeve surface, it has been proposed to provide a plating film made of a material different from these base materials on the surface of the aluminum alloy or stainless steel sleeve. (JP-A-3-41485). However, when forming a plating film, an electroplating film with a thickness of several microns or more is required to improve the wear resistance of the sleeve,
When such plating is performed, the thickness of the plating film varies, so that the dimensional accuracy of the sleeve is reduced, and as a result, the quality of the image is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a magnet roller which can easily produce a high magnetic force at a low cost and a magnet roller which can reduce man-hours and have excellent dimensional accuracy. Manufacturing method, a developing roller using the magnet roller, a developing roller capable of improving the abrasion resistance of the surface and reliably obtaining a high-quality image without a ghost phenomenon, and a method using the developing roller. It is an object of the present invention to provide a developing device.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that a bonded magnet composition in which a magnetic powder is dispersed in a resin binder and a magnet body and When a magnet roller is obtained by integrally molding shaft portions protruding from both ends or one end of the magnet main body, the strontium / barium element ratio (Sr / Ba ratio) is 1 to 10 as the magnetic powder.
It has been found that by using ferrite of No. 0, a high magnetic force can be obtained without impairing the fluidity of the bonded magnet composition during molding, and a magnet roller with high magnetic force and excellent dimensional accuracy can be obtained.

Therefore, according to the present invention, as a first magnet roller, a magnet main body and a shaft protruding from both ends or one end of the magnet main body with a bonded magnet composition in which magnetic powder is dispersed in a resin binder are integrally formed. In the molded magnet roller, the magnetic powder has a strontium / barium element ratio (Sr / Ba ratio) of 1 to 1.
The present invention provides a magnet roller which is ferrite No. 00.

The present inventor has also proposed a method of forming a plurality of magnetic poles by integrally molding a magnet main body and a shaft protruding from both ends or one end of the magnet main body with a bonded magnet composition in which magnetic powder is dispersed in a resin binder. In the case of obtaining a magnet roller having a magnetic pole, the anisotropy of the magnetic pole can be increased by setting the difference between the magnetic force of the high magnetic pole having the maximum magnetic force and the magnetic force of the low magnetic pole having the minimum magnetic force to be 100 G or more. In addition, it has been found that the magnetic force of a specific magnetic pole (for example, a developing pole) can be set relatively high, and a high-quality image can be obtained.

Accordingly, the present invention provides, as a second magnet roller, a magnet body portion and a shaft portion projecting from both ends or one end of the magnet body portion with a bonded magnet composition in which magnetic powder is dispersed in a resin binder. In a molded magnet roller, having a plurality of magnetic poles,
Also, a magnet roller is provided in which a difference between a magnetic force of a high magnetic pole having a maximum magnetic force and a magnetic force of a low magnetic pole having a minimum magnetic force is 100 G or more.

Further, the present inventor has made intensive studies to achieve the above object by improving the manufacturing method. As a result, the bonded magnet composition in which magnetic powder is dispersed in a resin binder is melted into a mold cavity. Injection injection molding, the magnet body portion and the shaft portion projecting from both ends or one end of the magnet body portion are integrally formed with the bonded magnet composition, and when the magnet roller is obtained, the mold is divided. By pushing the magnet body portion with an eject pin and removing the magnet roller composed of the magnet body portion and the shaft portion from the mold, a magnet roller having excellent dimensional accuracy without warpage or breakage is required. Can be easily and reliably obtained without increasing the outer peripheral surface portion or the end surface portion of the magnet main body to be molded or A gate is provided in the mold corresponding to the outer peripheral surface portion of the shaft portion, and the bonded magnet composition is injected and injected into the cavity of the mold through the gate, so that the bonded magnet composition in the cavity is formed. It has been found that the flow of the particles can be made uniform, and a decrease in dimensional accuracy due to a defective filling of the bonded magnet composition and the occurrence of a defective due to the non-filling can be reliably prevented.

Accordingly, the present invention provides, as a first manufacturing method, a bonded magnet composition obtained by dispersing magnetic powder in a resin binder using a mold, and using the bonded magnet composition to form a magnet main body and the magnet. By integrally molding a shaft portion protruding from both ends or one end of the main body portion, dividing the mold and pushing the magnet main body portion with an eject pin, the magnet roller including the magnet main body portion and the shaft portion A method of manufacturing a magnet roller, which is characterized in that the bonded magnet composition in which magnetic powder is dispersed in a resin binder is injected into a cavity of the mold in a molten state. Then, a magnet main body and a shaft protruding from both ends or one end of the magnet main body are integrally formed with the bonded magnet composition. In the method for manufacturing a gnet roller, a gate is provided in the mold corresponding to an outer peripheral surface portion or an end surface portion of the magnet main body portion to be molded or an outer peripheral surface portion of the shaft portion, and the cavity of the mold is passed through the gate. And a method of manufacturing a magnet roller, wherein the bonded magnet composition is injected and injected into the inside.

The first and second magnet rollers and the magnet rollers obtained by the first and second manufacturing methods are used, and a cylindrical sleeve is rotatably arranged along the outer periphery of these magnet rollers. A developing roller composed of a cylindrical sleeve rotatably disposed and a magnet roller disposed inside the sleeve, and a developing roller formed on the outer peripheral surface of the sleeve by a magnetic characteristic of the magnet roller. Forming a thin layer of the developer by carrying the developer, in this state, bringing the developer close to the image forming body, and supplying the developer by flying the developer onto the surface of the latent image holding member by the magnetic characteristics of the magnet roller; By forming a visible image on the surface of the image forming body, a good image can be reliably obtained by the good magnetic properties of the magnet roller.

Accordingly, the present invention comprises, as a first developing roller, a cylindrical sleeve rotatably disposed and a magnet roller disposed inside the sleeve. A developer is carried on the outer peripheral surface of the sleeve by the magnetic characteristics of the sleeve, and a thin layer of the developer is formed. In the developing roller for forming a visible image on the surface of the image forming body by supplying the developer by flying, the magnet roller may be the first or second magnet roller of the present invention or the first or second magnet roller of the present invention. A developing roller, which is a magnet roller obtained by the first or second manufacturing method, is provided.

The inventor of the present invention has proposed a developing roller comprising a cylindrical sleeve rotatably disposed and a magnet roller disposed inside the sleeve. As a result of examining the dimensional relationship, when the inner diameter of the sleeve was X mm,
By setting the outer diameter of the magnet roller disposed inside the sleeve in the range of (X-4) to (X-0.2) mm, the magnetic force of the magnet roller is effectively developed as a developing roller. According to the magnetic characteristics of the magnet roller, a developer is carried on the outer peripheral surface of the sleeve to form a thin layer of the developer, and in this state, the magnetic characteristics of the magnet roller are brought close to the image forming body. By spraying the developer on the surface of the image forming body to form a visible image on the surface of the image forming body, it was found that a high quality image could be obtained.

Accordingly, the present invention comprises, as a second developing roller, a cylindrical sleeve rotatably disposed and a magnet roller disposed inside the sleeve. A developer is carried on the outer peripheral surface of the sleeve by the magnetic characteristics of the sleeve, and a thin layer of the developer is formed. In the developing roller for forming a visible image on the surface of the image forming body by supplying the developer by flying, when the inner diameter of the sleeve is X mm, the outer diameter of the magnet roller is (X-4). To (X-0.2) mm.

Further, the present inventor has repeatedly studied to obtain a developing roller capable of improving the abrasion resistance of the surface and reliably obtaining a high-quality image free of a ghost phenomenon. A developing roller having a magnet roller, in particular, a cylindrical sleeve rotatably disposed, and a magnet roller disposed inside the sleeve, the magnetic roller having a magnetic roller formed on the outer peripheral surface of the developing roller. The developer is carried according to the characteristics to form a thin layer of the developer, and in this state, the developer is caused to fly to the surface of the image forming body by the magnetic characteristics of the magnet roller in the vicinity of the image forming body and supplied. When a visible image is formed on the surface of the image forming body, a resin component capable of improving the abrasion resistance of the surface is provided on the surface of the developing roller. If JIS K71 as a resin component
By using a resin component having an elongation at break of 10% or less according to the provisions of 13, the wear resistance of the developing roller surface can be improved without lowering the dimensional accuracy of the developing roller surface such as a sleeve. The present inventors have found that a high-quality image free from image defects such as a ghost phenomenon can be reliably obtained over a long period of time, and the present invention has been completed.

Therefore, according to the present invention, as a third developing roller, a thin layer of the developer is formed by carrying the developer on the outer peripheral surface of the developing roller by the magnetic characteristics of the magnet roller. A developing roller that forms a visible image on the surface of the image forming body by supplying the developer by flying it onto the surface of the image forming body by the magnetic characteristics of the magnet roller;
A developing roller having a resin component having an elongation at break of 10% or less according to K7113 is provided.

Here, in the third developing roller, the surface roughness of the developing roller changes by applying the resin component to the surface of the developing roller such as a sleeve. Therefore, the present inventor has conducted further studies to ensure proper surface roughness without impairing the effect of the application of the resin component even after the application of the resin component. As a result, the surface of the developing roller such as the sleeve is formed. The surface roughness of the base material,
By optimizing the relationship with the thickness of the resin component applied to the surface of the sleeve and the like, and forming the resin component having a low elongation ratio thinner than the surface roughness of the base material of the developing roller surface such as the sleeve, a good surface is obtained. When the roughness can be maintained and the JIS 10-point average roughness Rz of the surface of the base material such as the sleeve is a and the thickness of the resin component applied to the surface of the base material is b, the relationship is 0.01 < By adjusting so that b / a <2, it has been found that development characteristics and durability can be improved while maintaining an appropriate surface roughness and maintaining good developer transportability.

Therefore, the present invention provides, as a preferred embodiment of the third developing roller, a JIS 10-point average roughness Rz of the surface of the base material constituting the surface portion of the developing roller, a being given to the surface of the base material. Where b is the thickness of the resin component that
The third developing roller satisfies the relationship of 01 <b / a <2.

The first to third developing rollers are:
A thin-layered developer carried on the outer peripheral surface is supplied by flying onto the surface of the image forming body by the magnetic properties of the magnet roller to form a visible image on the surface of the image forming body. A latent image holding member having an electrostatic latent image held on the surface of a photoreceptor or the like is used as a body, and a developer is supplied to the surface of the latent image holding member to visualize the electrostatic latent image on the surface of the latent image holding member. It is preferably used in such a case, and can reliably reproduce a high-quality image on the surface of the latent image holding member.

Accordingly, in the present invention, the developer is brought close to the surface of the latent image holding member which holds the electrostatic latent image on the surface while the developer is carried on the outer peripheral surface, and the developer is transferred to the latent image holding member. In a developing device comprising a developing roller for adhering to the electrostatic latent image on the surface of the holding member to visualize the electrostatic latent image, the first, second, or third developing roller according to the present invention may be used as the developing roller. The present invention provides a developing device characterized by using.

Hereinafter, the present invention will be described in more detail.
The first and second magnet rollers of the present invention are, for example, as shown in FIG. 1, a bonded magnet composition in which a magnetic powder is dispersed in a resin binder, and a magnet main body 1 and both ends or one end of the magnet main body. 2 protruding from the shaft (two shafts 2 and 2 protruding from both ends in the figure)
Is a magnet roller formed integrally.

First, the first magnet roller will be described. As shown in FIG. 1, the magnet roller is made of a bonded magnet composition in which a magnetic powder is dispersed in a resin binder. In a magnet roller formed integrally with a shaft portion 2 protruding from both ends or one end,
Strontium / barium element ratio (Sr / Ba ratio) is 1
~ 100 ferrites are used.

Examples of the resin binder include polyamide resins such as nylon 6 and nylon 12, polystyrene resins, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyphenylene sulfide resin (PPS), and ethylene-vinyl acetate copolymer. Polyolefins such as coalescing resin (EVA), ethylene-ethyl acrylate resin (EEA), epoxy resin, ethylene-vinyl alcohol copolymer resin (EVOH), polypropylene resin, polyethylene and polyethylene copolymer, and the structure of these polyolefins Modified polyolefins into which reactive functional groups such as a maleic anhydride group, a carboxyl group, a hydroxyl group, and a glycidyl group have been introduced, and one or more of these can be used in combination. Although not particularly limited, polyamide resins, particularly nylon 6 having a number average molecular weight of 8,000 to 10,500 are preferably used among them.

As the magnetic powder dispersed in the binder, an anisotropic or isotropic ferrite is used. In the first magnet roller of the present invention,
As the ferrite, one having a strontium / barium element ratio (Sr / Ba ratio) of 1 to 100 is used.

Here, the quantification of the Sr / Ba ratio can be performed by a usual elemental analysis method. Specifically, the analysis method includes electron beam microanalysis (EPMA) and wavelength dispersive X-ray spectroscopy (WDX). ), Energy dispersive X-ray spectroscopy (E
DX), X-ray fluorescence analysis, inductively coupled plasma emission analysis (I
CP-AES). For example, when performing quantification by the above-mentioned EDX, Hitachi S-
Using a commercially available analyzer such as 2700, the accelerating voltage is 25k.
Analysis is performed under appropriate conditions such as eV, magnification 500 times, and beam current 0.1 nA, and the Sr / Ba ratio is calculated from the peak values of strontium (Sr) and barium (Ba) in the obtained EDX scattered X-ray spectrum. Is what you can do. The more preferable range of the Sr / Ba ratio is 1
10 to 10.

The ferrite used as the magnetic powder is not particularly limited, but has an average particle size of 1.
BET at 2 to 1.55 μm, especially 1.3 to 1.5 μm
Specific surface area is 1 to 2.5 m ² / g, especially 1.2 to 1.7 m ²
/ G of particles. In this case, the average particle diameter is measured by a constant pressure air permeation method,
The BET specific surface area is a value measured by an N ₂ gas adsorption method using a specific surface area measuring device.

The mixing ratio of the ferrite as the magnetic powder is appropriately selected according to the required strength of the magnetic force, and is not particularly limited. Weight% (density is 2.5 ~
(About 3.5 g / cm ³ ).

In addition to the binder component and the magnetic powder, a filler having a large reinforcing effect such as mica, whisker, talc, carbon fiber, glass fiber, etc. can be added to the above-mentioned bonded magnet composition, if necessary. That is, when the magnetic force required for the molded product is relatively low and the filling amount of the magnetic powder is small, the rigidity of the molded product tends to be low. In such a case, mica, whisker, etc. The molded article can be reinforced by adding a filler. In this case, the filler preferably used in the present invention is preferably mica or whisker, and the whisker is a non-oxide whisker made of silicon carbide, silicon nitride or the like, or Zn.
Metal oxide whiskers made of O, MgO, TiO ₂ , SnO ₂ , Al ₂ O _{3 and the} like, and double oxide whiskers made of potassium titanate, aluminum borate, basic magnesium sulfate, etc., are exemplified. Among them, double oxide whiskers are particularly preferably used because they can be easily combined with plastic.

The mixing ratio when these fillers are used is not particularly limited, but is usually 2 to 2 of the total composition.
It is about 32% by weight, especially about 5 to 20% by weight. In addition,
Additives other than the above fillers may be added to the bonded magnet composition as long as the object of the present invention is not deviated.

The first magnet roller is formed by integrally molding the magnet main body 1 and at least one end of the shaft 2 with the above-described bonded magnet composition. In this case, the molding method is not particularly limited. A conventionally known injection molding method or extrusion molding method can be suitably adopted, and in particular, a first manufacturing method or a second manufacturing method of the present invention described later, or a first and a second manufacturing method thereof. It is preferable to mold by a method combining the methods.

The magnet roller is formed by molding the above bonded magnet composition as shown in FIG. 1 and magnetizing it to desired magnetic properties. In this case, the magnetizing method is such that a mold is used at the time of molding. A magnetic field is arranged around the cavity to orient the magnetic powder and then demagnetized and re-magnetized, or a method of magnetizing with the magnetic field simultaneously with molding is preferably employed. Can be.

Next, as shown in FIG. 1, the second magnet roller of the present invention is composed of a magnet body 1 and both ends or one end of the magnet body 1 with a bonded magnet composition in which magnetic powder is dispersed in a resin binder. In the magnet roller formed by integrally forming the protruding shaft portion 2, the difference between the magnetic force of the high magnetic pole having the plurality of magnetic poles and the magnetic force of the low magnetic pole having the minimum magnetic force is 100G or more. As described above, the more preferable difference between the magnetic force of the high magnetic pole and the magnetic force of the low magnetic pole is 200 to 400 G or more.

In this case, the number of magnetic poles is not particularly limited as long as it is two or more.
In this case, magnetic poles of the same polarity may be adjacent to each other.

The high magnetic pole having the maximum magnetic force is not particularly limited, but is preferably a developing pole (a pole that causes a developer to fly to a partner member such as an image forming body). When it is desired to further increase the magnetic force of the developing pole, the magnetic force of the other magnetic pole having the same polarity as that of the developing pole can be reduced to relatively improve the magnetic force of the developing pole. High quality images can be obtained.

This magnet roller is formed of a bonded magnet composition in which magnetic powder is dispersed in a resin binder. In this case, the resin binder, magnetic powder, filler, and other additives constituting the bonded magnet composition are And the same as the first magnet roller. In this case, as the magnetic powder, ferrite having the same physical properties as those used in the first magnet roller is preferably used, but the magnetic powder is not limited to this, and ordinary ferrite or other magnetic powder is used. Powder can also be used.

Other magnetic powders include strontium-free ferrite powders such as barium ferrite and S
Rare earth alloy powders such as m-Co alloy, Nd-FB alloy and Ce-Co alloy can be exemplified.

The first and second magnet rollers are:
As described above, the magnet main body 1 and at least one end of the shaft portion 2 are integrally formed from the above-described bonded magnet composition. However, if necessary, a drive for rotating the shaft portion 2 with a magnet roller is performed. A gear may be provided, and in this case, a rotary drive gear may be formed integrally with the shaft portion 2 using the bonded magnet composition. As shown in FIG. 2, a semicircular or other fitting portion 21 is formed at the distal end of the shaft portion 2, and the shaft portion 2 is used as a mating member by the fitting portion 21. It may be fixed to a fixed part, and FIGS. 2 (B1), (B2),
As shown in (C1) and (C2), the shaft portion 2 having the fitting portion 21 is replaced with a frusto-conical or columnar large-diameter portion 22.
a, 22b may be formed at the end of the magnet main body 1.

The second magnet roller can also suitably employ a conventionally known injection molding method or extrusion molding method. In particular, a first manufacturing method of the present invention, which will be described later, The manufacturing method, or the first and second
It is preferable to mold by a method combining the production methods of the above.

Next, in each of the first and second manufacturing methods of the present invention, a bonded magnet composition in which magnetic powder is dispersed in a resin binder is molded using a mold, and the bonded magnet composition is magnetized with the bonded magnet composition. A magnet roller is obtained by integrally molding a main body and a shaft protruding from both ends or one end of the magnet main body.

First, a first manufacturing method will be described. This first manufacturing method is, for example, as shown in FIG. 3, a two-part mold in which an upper mold 31 and a lower mold 32 are joined in a separable manner. 3, the bonded magnet composition is injected and injected into the cavity 33 of the mold 3, and the magnet main body 1 and the shaft 2 protruding from both ends or one end of the magnet main body 1 (in FIG. After integrally forming the shaft portions 2, 2), as shown in FIG. 3 (B), the upper die 31 and the lower die 32 are separated from each other, and the magnetic roller is fixed by an eject pin 4 provided on the upper die. Of the magnet body 1 and the shafts 2 and 2 are released from the mold 3 by pushing the magnet body 1 of the above. Excellent accuracy And the magnet roller is obtained easily and reliably without increasing the number of processes.

Here, the mold 3 only needs to have the eject pin 4, and the other structure can be the same as that of a conventional ordinary mold. May be divided into three or more. Further, the eject pin may be provided so as to press the magnet main body 1 portion of the obtained magnet roller. In this case, it is preferable to perform demolding by pressing the magnet roller evenly along the length direction. For this reason, as shown in FIG. 3, both ends and an intermediate portion are pressed along the length direction of the magnet roller. It is preferable to provide the eject pins at three places. However, when the length of the magnet roller is short, two places at both ends or one place at the center in the longitudinal direction may be pressed.
Conversely, if the length is long, it is preferable to provide eject pins at four or more locations along the length direction. Further, if the magnet roller has a large diameter, a plurality of eject pins may be provided along the circumferential direction of the roller. It is preferable that the ejection pins are provided and the outer peripheral surface of the magnet main body 1 is pressed as evenly as possible to perform the demolding.

The eject pin 4 is not particularly limited, but is preferably formed by processing a concave surface having the same curvature as the outer peripheral surface of the magnet main body 1 of the magnet roller for forming the tip. Thereby, the outer peripheral surface of the magnet main body 1 can be formed into a smooth curved surface as designed. The diameter of the eject pin 4 is not particularly limited, but is usually about 2 to 4 mm.

Next, the second manufacturing method will be described. In the second manufacturing method, a bonded magnet composition in which a magnetic powder is dispersed in a resin binder is injected and injected into a mold cavity. When a magnet roller is obtained by integrally molding a magnet main body portion and a shaft portion protruding from both ends or one end of the magnet main body portion with a bonded magnet composition, for example, as shown in FIG. A gate (not shown) is provided in the mold 3 corresponding to the outer peripheral surface portion 5a or the end surface portion 5b of the magnet main body 1 or the outer peripheral surface portion 5c of the shaft portion 2, and the mold 3 is passed through the gate. In this case, the bonded magnet composition is injected into the cavity 33, whereby the flow of the bonded magnet composition in the cavity 33 can be made uniform. Decrease in dimensional accuracy filling by failure of de magnet composition, is intended to reliably prevent to high-performance magnet roller occurrence of defects due unfilled can be surely obtained.

That is, conventionally, when the magnet main body 1 and the shaft 2 are integrally formed with the bonded magnet composition by injection molding, the bonded magnet composition is indicated by reference numeral 5d in FIG. Injection and injection into the cavity 33 from the end face of the shaft portion 2 is performed. However, in this method, there is a case where the resin cannot be completely filled to every corner in the cavity 33, and the obtained magnet roller The magnet body 1 and the shafts 2 and 2 cannot accurately transfer the cavity surface of the mold, resulting in reduced dimensional accuracy,
There may be places where the resin is not filled inside, but the resin is filled from the outer peripheral surface portion 5a or the end surface portion 5b of the magnet main body 1 or the outer peripheral surface portion 5c of the shaft portion 2 as described above. Accordingly, the flow of the resin is made uniform, and such a disadvantage does not occur, and a magnet roller having excellent dimensional accuracy can be reliably obtained.

The gate may be provided at any position as long as it corresponds to the outer peripheral surface portion 5a or the end surface portion 5b of the magnet main body 1 or the outer peripheral surface portion 5c of the shaft portion 2. The number of gates may be one or more, and is appropriately selected according to the size of the magnet roller, but usually prevents the occurrence of welds, flow marks, etc., except when a large magnet roller is used. For this reason, it is preferable that the number is one.

When carrying out the first and second manufacturing methods, molding conditions other than those described above can be ordinary conditions. In this case, a magnetic field is formed around the cavity 33 of the mold 3 used for molding, and the magnet is magnetized simultaneously with the molding according to the target magnetic force pattern, or the magnetic powder in the bonded magnet composition is removed. It can be oriented to a desired state.

The bonded magnet compositions used in the first and second production methods are obtained by dispersing and mixing magnetic powder in a resin binder and blending a filler and other additives as necessary. In this case, as the resin binder, magnetic powder, filler, and the like, the resin binder, magnetic powder, and filler exemplified in the first and second magnet rollers can be used, and of course, other materials may be used. .

The first and second magnet rollers and the magnet rollers obtained by the first and second manufacturing methods are used in a developing mechanism of an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus. It is preferably used as a magnet roller to be used. In particular, as shown in FIGS. 4 and 5, it is preferably used as a magnet roller 7 disposed inside a developing sleeve 6 which rotates while carrying a toner 10 on its surface. By using the magnet roller according to the present invention, a good image can be reliably obtained due to the good magnetic properties of the magnet roller.

Accordingly, the present invention provides, as a first developing roller, for example, a developing roller in which these magnet rollers are disposed inside a rotating sleeve. The first developing roller carries a developer on the outer peripheral surface of the sleeve by a magnetic property of the magnet roller to form a thin layer of the developer. A visible image is formed on the surface of the image forming body by supplying the developer by flying it onto the surface of the image forming body due to the magnetic characteristics of the roller. For example, as shown in FIG. The developing roller of the present invention comprising a sleeve 6 and a magnet roller 7 is provided between a toner applying roller 8 for supplying the toner and a photosensitive drum 9 (image forming body) holding the electrostatic latent image. Is arranged in a state where the outer peripheral surface of the drum 6 is close to the surface of the photosensitive drum 9, and the sleeve 6, the photosensitive drum 9, and the toner applying roller 8 are respectively rotated in the arrow direction in FIG. 10 is supplied to the surface of the sleeve 6 by the toner application roller 8, the toner is carried on the surface of the sleeve 6 by the magnetic characteristics of the magnet roller 7 and conveyed, and the toner is arranged into a uniform thin layer by the layering blade 11. In this state, when the sleeve 6 rotates and the toner is conveyed to a portion close to the photosensitive drum 9,
The toner formed in the thin layer flies from the surface of the sleeve 6 onto the latent image on the photosensitive drum 9 due to the magnetic characteristics of the magnet roller 7 and adheres, and the electrostatic latent image on the photosensitive drum 9 is visualized. . In the drawing, reference numeral 12 denotes a transfer unit, which transfers a toner image to a recording medium such as paper. Reference numeral 13 denotes a cleaning unit. The remaining toner is removed.

Further, according to the present invention, as the second developing roller, like the developing roller shown in FIGS.
A developer (toner) 10 is carried on the outer peripheral surface of the sleeve 6 by the magnetic characteristics of the magnet roller 7 to form a thin layer of the toner 10. The toner 10 is caused to fly and supplied to the surface of the image forming body 9 by the magnetic characteristics of the magnet roller 7 in the vicinity of the image forming body (photosensitive drum) 9 so that a visible image is formed on the surface of the image forming body 9. In the developing roller to be formed, the inner diameter a of the sleeve 6 is set to X mm
When the outer diameter b of the magnet roller is (X−
4) A developing roller characterized by having a thickness of (X-0.2) mm.

In the developing roller, the magnetic force of the magnet roller 7 is effectively expressed as the developing roller by optimizing the positional relationship based on the dimensions of the sleeve 6 and the magnet roller 7 disposed inside the sleeve. To obtain high quality images.

The sleeve 6 constituting the developing roller is not particularly limited, and a normal sleeve formed of a resin or a metal material such as an aluminum alloy, stainless steel, a copper alloy or the like can be used. It is preferable to use a sleeve on the surface of which a resin having a specific elongation described later is applied. Further, the magnet roller 7 constituting the developing roller is not particularly limited, and a roller formed of a normal bonded magnet composition or a roller formed of a sintered magnet can be used. It is preferable to use the first and second magnet rollers or the magnet rollers manufactured by the first or second manufacturing method of the present invention.

Further, according to the present invention, as the third developing roller, for example, like the developing roller shown in FIGS. A magnetic roller 7 disposed on the inner side, and a developer (toner) 10 is carried on the outer peripheral surface of the sleeve 6 by a magnetic characteristic of the magnet roller 7 to form a thin layer of the toner 10. A visible image is formed on the surface of the image forming member 9 by flying the toner 10 onto the surface of the image forming member 9 by the magnetic characteristics of the magnet roller 7 in proximity to the image forming member (photosensitive drum) 9 and supplying the toner. The present invention provides a developing roller in which a resin component having an elongation at break of 10% or less according to JIS K7113 is applied to a surface portion, specifically, an outer peripheral surface of the sleeve 6.

The developing roller is provided with a resin component having the above-mentioned specific elongation rate on the surface of the developing roller such as the sleeve 6, so that the surface of the developing roller,
The wear resistance is improved without lowering the dimensional accuracy of the surface, and a high-quality image free from image defects such as a ghost phenomenon can be reliably obtained over a long period of time.

Here, although the mechanism of preventing the image density from being reduced due to long-term use by applying the resin component to the surface of the developing roller such as the sleeve 6 is not clear, it is presumed as follows. That is, the presence of a resin component having a very low elongation at break elongation of 10% or less on the surface of the developing roller such as the sleeve 6 can effectively prevent the abrasion of the surface of the developing roller during development. In addition, even if the resin component is used for a long period of time, the change in characteristics of the resin component is extremely small, and a good surface state is maintained. Further, in this developing roller, the charging performance of the developer can be appropriately controlled by appropriately selecting the resin component according to the application and the developer, and a good image can be reliably obtained. is there.

The sleeve 6 used for the third developing roller can be made of a usual material such as a resin or a metal material such as an aluminum alloy, stainless steel, or a copper alloy, and is particularly limited. Although not necessarily, usually, a sleeve made of an aluminum alloy is preferably used in terms of material cost, workability, and the like.

The sleeve 6 of the third developing roller
Although a resin component is applied to the surface of a cylindrical base material made of the above-described metal material or the like, but is not particularly limited in this case, in order to improve image quality, before the resin component is applied. Fine irregularities due to blasting or the like can be formed on the surface of the base material of the sleeve 6. As a method of blast treatment, air blast method of pressure type or suction type, vacuum blast method, water blast method,
Any method such as a centrifugal blast method may be used. The abrasive used for the blasting process can be selected from cast iron grid, steel grid, copper slag, nickel slag, fused alumina, silicon carbide, and the like. The sleeve 6 is used for the purpose of improving the adhesion to the resin component. Glass beads, plastic beads, sand, or walnut shells may be used to polish or clean the surface of the base material. The processing conditions such as pressure, distance, and angle of the blast processing are not particularly limited, and can be set according to the shape of the target minute unevenness, the degree of surface polishing, and the like.

Further, in order to improve the adhesion between the surface of the base material of the sleeve 6 and the resin component, an appropriate pre-treatment other than the blast treatment may be performed on the surface of the base material before the resin component is applied. it can. Examples of pretreatment include solvent washing, acid / alkali washing, water washing, flame treatment, corona discharge treatment, plasma treatment, etc. Water washing and plasma treatment are particularly effective in terms of high treatment effect and the need for waste liquid treatment. It is suitable.

The third developing roller according to the present invention comprises:
In the developing roller of FIG. 4, that is, in the developing roller of FIG. 4, a resin component having an elongation at break of 10% or less according to JIS K7113 is applied to the surface of the sleeve 6.
In this case, there is a developing roller of a type in which a developer is carried on the surface of a magnet roller and a developer is supplied to an image forming body without using a sleeve. In the case of this type of developing roller, the above resin is applied to the surface of the magnet roller. Ingredients are provided.

The resin component is not particularly limited as long as it has the above-mentioned elongation percentage.
Urea resin, melamine resin, alkyd resin, modified alkyd resin such as phenol-modified / silicone-modified, oil-free alkyd resin, acrylic resin, silicone resin, fluorine resin, phenol resin, polyamide resin, epoxy resin, polyester resin, maleic acid resin, Urethane resins and the like can be mentioned. Among these, from the viewpoints of film-forming properties and adhesion, in particular, selected from urea resins, melamine resins, silicone resins, phenol resins, various modified alkyd resins, oil-free alkyd resins, acrylic resins, and moisture-curable urethane resins. Species or two or more resins are preferably used. Among them, various modified alkyd resins or mixed resins of melamine resins and oil-free alkyd resins and phenol resins are preferably used because of low elongation and high mechanical strength. . In addition, melamine resins are preferably used because they have an electron supply property due to unpaired electrons of the nitrogen group in the resin, and phenol resins are preferably used because they have electronic dielectric properties due to their high dielectric constant. Is done.

Here, the resin component is J as described above.
10% elongation at break according to IS K7113
The following, preferably 5% or less is used. In this case, if the elongation at the time of the break exceeds 10%, the deformation of the roller surface becomes large, the toner control becomes difficult, and the density of the image is reduced.

The resin component may or may not contain a conductive material, and can be appropriately selected according to the adjustment of the resistance of the roller surface such as the sleeve 6 and the like. Although not particularly limited, when a conductive material is added, a conductive powder is suitably used, and carbon black is particularly preferably used.

As a means for applying such a resin component to the surface of the developing roller such as the sleeve 6, a method of surface-treating the sleeve 6 or the like with a resin solution containing the above resin component is suitably employed. In this case, after preparing the resin solution, the surface treatment can be performed by a spray method, a roll coater method, a dipping method, or the like. For example, for the surface treatment by dipping, a method of immersing the resin solution in a resin solution at room temperature for 5 seconds to 5 minutes, preferably 10 seconds to 1 minute, pulling it up, and drying it can be adopted. When the spray method is adopted, the concentration of the resin in the processing solution can be set higher than that of the dipping method, and for example, a resin whose concentration is adjusted to 10 to 60% can be used. The solvent for preparing the resin solution may be any solvent as long as it dissolves the resin, but usually, methanol, ethanol,
Lower alcohols such as isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, toluene and xylene are preferably used.

Although the surface treatment with the resin component described above can reduce the friction of the surface of the developing roller such as the sleeve to some extent, various additives can be used to further reduce the friction. In this case, silicone resin, silicone resin powder, fluorine-based and silicone-based surfactants, silicone-based coupling agent and silica powder can be used as additives capable of reducing friction without lowering the uniformity of the surface treatment. It is preferably used.

Examples of the silicone resin include those soluble in a solvent, for example, methyl silicone, methyl phenyl silicone, modified products thereof, and silicone epoxy block copolymer.

Examples of the silicone resin powder include methyl silicone or methyl phenyl silicone polymer,
Examples include fine powder of an amino group-modified silicone polymer, and those having a true spherical shape and an amorphous shape having an average particle size of 0.1 to 100 μm are preferably used.

Examples of the fluorinated surfactant include ionic surfactants in which an alkyl fluoride is bonded to a carboxylic acid, a carboxylate, or a sulfonic acid salt, and nonionic surfactants in which an alkyl fluoride is bonded to an alcohol or an ether. And polymer-based polymers such as polymers and copolymers containing alkyl fluoride in the side chain and main chain.

Examples of the silicone-based surfactant include high-molecular-weight surfactants such as conjugates of methyl silicone such as siloxane oxyethylene with hydrophilic and lipophilic segments, and copolymers of methyl silicone and acrylic segments. Things.

As the silicon-based coupling agent, not only an ordinary silane coupling agent but also an amino group at the terminal,
Includes silanes into which isocyanate groups, vinyl groups, etc. have been introduced.

These may be used alone or in combination of two or more. In addition, a fluororesin also effectively acts as a friction reducing agent. The amount of the friction reducing agent to be used is 1 to 100 parts by weight, preferably 10 to 75 parts by weight, based on 100 parts by weight of the resin component. When an ionic conductive material is used as the conductive material, the amount of the ionic conductive material to be added to the resin solution is adjusted by the amount of the resin component 10.
It is preferably 0.001 to 1 part by weight based on 0 part by weight.

Here, the base material constituting the surface portion of the developing roller of the present invention, that is, the sleeve 6 in the developing roller of FIG. 4 is not particularly limited, but the surface roughness of the base material of the sleeve 6 That is, the surface roughness (JIS 10 point average roughness Rz) of the sleeve 6 before applying the resin component to the surface.
(Μm)) as a, and b as the thickness (μm) of the resin component applied on the base material of the sleeve 6, 0.01
It is preferable to adjust the surface roughness of the base material of the sleeve 6 and the thickness of the resin component so as to satisfy the relationship of <b / a <2, thereby maintaining an appropriate surface roughness. Charging property and durability can be improved while maintaining excellent developer transportability. Note that if b / a ≧ 2,
In some cases, the surface roughness of the sleeve 6 becomes low and the toner conveyance amount becomes insufficient. On the other hand, when b / a ≦ 0.01, the durability is lowered and the effect of the present invention may not be sufficiently obtained. .

In this case, the surface roughness a of the base material of the sleeve 6 and the thickness b of the resin component need only satisfy the above relationship, and are not particularly limited. Roughness a, that is, JIS 10-point average roughness Rz of the base material surface
Is 30 μm or less, particularly 0.1 to 30 μm,
The thickness b of the resin component is preferably about 15 μm, while the thickness b of the resin component may be a thickness satisfying the above relationship with respect to such a suitable surface roughness Rz (a). The thickness is preferably about 0.5 to about 0.5 μm, particularly preferably about 15 to 1 μm. The surface roughness of the sleeve 6 after the application of the resin component is not particularly limited.
S10 point average roughness Rz 30 μm or less, particularly 10 to 1 μm
m is preferable.

Here, the resin component applied to the surface of the sleeve 6 by the above-described surface treatment, even if it is in the form of a film that covers the entire surface of the sleeve 6, is contained in the concaves of minute irregularities on the surface of the sleeve 6. Even if the component is in a dispersed state, the sleeve 6 further covers most of the surface of the sleeve 6,
It may be in a state where the tip portion of the convex portion of the minute unevenness on the surface is partially exposed. In this case, the thickness b of the resin component is the average thickness of the resin component applied to the surface of the sleeve 6 in these various forms, and can be measured by the following method. For example, it can be obtained by dividing the surface of the sleeve into a plurality of 1 cm × 1 cm square sections, observing the cross section, measuring the thickness of each resin, and dividing the total of these thicknesses by the number of measurement sections. The means for observing the thickness of the resin component is not particularly limited, and a known means such as an electron or optical microscope can be used.

There is no particular limitation on the magnet roller 7 constituting the third developing roller, and a roller formed of a usual bonded magnet composition or a roller formed of a sintered magnet can be used. It is preferable to use the first and second magnet rollers of the present invention or the magnet rollers manufactured by the first or second manufacturing method of the present invention. The size and positional relationship between the magnet roller 7 and the sleeve 6 are not particularly limited, and the magnet roller 7 and the sleeve 6 may be arranged in a normal state. It is preferable to arrange so as to satisfy the dimensional relationship between the sleeve 6 and the sleeve 6.

Each of the first to third developing rollers according to the present invention can be incorporated in a normal developing device using a developer such as toner or carrier, and particularly, an electrostatic latent image is held on the surface of a photosensitive drum or the like. Supply the developer to the latent image holding member
It is suitably used for a developing device for visualizing a latent image on the surface of the latent image holding member, and can be used by being incorporated in, for example, the developing device shown in FIG.

The first to third developing rollers are
As shown in FIG. 5, it is preferably used when the electrostatic latent image held on the surface of the photosensitive drum 9 is visualized with a developer. Is not limited to the photosensitive drum described above, but may be a belt-shaped or other non-drum-shaped latent image holding member, or paper as a recording medium, OH
The present invention can be suitably applied to a use in which a developer is directly supplied to paper sheets such as P and photographic paper to form a visible image on these paper sheets. For example, as in a mechanism disclosed in Japanese Patent Application Laid-Open No. 8-129293, in a state where a back electrode roller is disposed on the back side of paper such as paper or OHP, a developer is applied to the front side of the paper sheet. By bringing the carried developing roller close to and flying the developer on the developing roller toward the back electrode roller while controlling the developer on the aperture electrode, the paper disposed between the back electrode roller and the developing roller is controlled. The developing roller of the present invention can also be suitably used as a developing roller for supplying a developer to the leaves and forming a visible image on the paper.

[0080]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 Using the mold shown in FIG. 3, a bonded magnet composition having the following composition was injected and injected from a portion corresponding to the outer peripheral surface portion of the magnet main body indicated by reference numeral 5a in the figure. Thus, a magnet roller in which the magnet main body 1 and the shaft portion 2 were integrally formed as in the case of the roller shown in FIG. 1 was formed. At this time, the cavity 3 of the mold 3
A magnetic field is formed around 3 and magnetized simultaneously with molding.
The magnetic pattern of the N pole was 2 poles and the S pole was 2 poles. After the molding is completed, as shown in FIG. 3 (B), the mold 3 is separated and the magnet main body 1 is separated by three eject pins 4.
By pressing the surface, the roller is released from the mold 3 and the length of the magnet body 1 is 310 mm and the outer diameter is 16 m.
m, a magnet roller having a shaft portion 2 with a diameter of 6 mm was obtained. In addition, each eject pin 4 was processed at its tip end surface into a concave curved surface having the same curvature as that of the surface of the magnet main body 1.

Bonded magnet composition (pellet) Binder: Nylon-6 (number average molecular weight = 10000) 10% by weight Magnetic powder: Sr ferrite (Sr / Ba ratio = 3.4, average particle diameter = 1.43 μm, BET) Specific surface area = 1.7 m ² / g) 90% by weight Injection molding conditions Cylinder temperature: 290 to 300 ° C. Mold temperature: 110 to 120 ° C. Injection pressure: 700 [kg / cm ² ]

With respect to the obtained magnet roller, the following items were evaluated. Surface magnetic force measurement A probe was placed near the surface of the magnet roller, and the surface magnetic force was measured while rotating the magnet roller with a Gauss meter. The magnetic force of the magnetic pole having the maximum magnetic force was 900 G and the magnetic force of the magnetic pole having the minimum magnetic force was 600 G. Yes, the difference in magnetic force between the maximum magnetic pole and the minimum magnetic pole was 300G. There was no disturbance of magnetic force near the eject pin traces and no disturbance of the magnetic force near the eject pin traces. Also,
The rollers had no warpage and maintained good dimensional accuracy. Appearance Appearance was good and there was no disturbance of magnetic force in the length direction.

Comparative Example 1 A magnet roller was obtained in the same manner as in Example 1, except that a bonded magnet composition having the following composition was used. Bonded magnet composition (pellet) Binder: Nylon-6 (number average molecular weight = 10000) 10% by weight Magnetic powder: Ba ferrite (Sr / Ba ratio = 0.5, average particle diameter = 1.44 μm, BET specific surface area = 1.6 m ² / g) 90% by weight

The following items were evaluated for the obtained magnet roller. When the surface magnetic force was measured in the same manner as in Example 1, the magnetic force of the magnetic pole having the maximum magnetic force was 500 G, the magnetic force of the magnetic pole having the minimum magnetic force was 250 G, and the magnetic pole having the maximum magnetic force and the magnetic pole having the minimum magnetic force were measured. The difference in magnetic force was 250G.

Example 2, Comparative Example 2 A pipe having an inner diameter of 18 mm and an inner diameter of 2 mm were formed using an aluminum alloy [6063].
A 7 mm pipe is prepared, and each outer peripheral surface is pressurized air blasted using Alundum # 46 to adjust the surface roughness to 7.0 μm in JIS 10-point average roughness Rz. It was created.

The two sleeves thus obtained were arranged rotatably, and the magnet roller of Example 1 was arranged inside each sleeve to produce two types of developing rollers. The surface magnetic force of each of the developing rollers was measured by the following method. Place the probe near the sleeve surface of the developing roller for surface magnetic force measurement ,
The surface magnetic force was measured while rotating the sleeve with a Gauss meter, and the maximum magnetic force was determined. Table 1 shows the results.

[0088]

[Table 1]

Example 3 Example 1 was repeated except that molding was performed under the following conditions using a bonded magnet composition having the following composition.
A magnet roller was obtained in the same manner as described above. Bonded magnet composition (pellet) Binder: 10% by weight of ethylene-ethyl acrylate (EEA) Magnetic powder: 90% by weight of Sr ferrite Injection molding conditions Cylinder temperature: 230 to 250 ° C Mold temperature: 50 to 70 ° C Injection pressure: 700 [Kg / cm ² ]

On the other hand, a pipe having an inner diameter of 18 mm was prepared using an aluminum alloy [6063], and the outer peripheral surface thereof was subjected to a pressurized air blast treatment using Alundum # 46 to determine the surface roughness according to JIS 10 point average roughness. 7.0μ at Rz
m and a sleeve was made.

Next, a mixed resin obtained by mixing an oil-free alkyd resin and a melamine resin (in this order, Beccolite M-6402 and Super Beckamine L110, both manufactured by Dainippon Ink and Chemicals, Inc.) at a ratio of 4: 1 was mixed in toluene. To 10
A resin solution was prepared by dissolving the solution in a concentration by weight, and the sleeve was immersed in the resin solution, pulled up, heated and dried, and subjected to a surface treatment. Observing the fracture surface of this sleeve, the thickness of the mixed resin applied to the sleeve surface by the surface treatment was 5 μm (average, the same applies hereinafter).
Met.

On the other hand, JIS K7113 was used by using a mixed resin of the above oil-free alkyd resin and melamine resin.
Prepare the first type test piece specified in JIS K71
When a tensile test was performed according to the provisions of Example 13, the elongation at break was less than 3%.

The developing roller having the same configuration as that shown in FIG. 4 was prepared by disposing the magnet roller inside the sleeve.

Example 4 Example 3 was repeated except that the surface treatment of the sleeve was performed using a resin solution in which a resol type phenol resin PR50232 (manufactured by Sumitomo Durez) was dissolved in a methyl ethyl ketone solvent at a concentration of 10% by weight.
A developing roller was prepared in the same manner as described above. Observation of the fracture surface of this sleeve revealed that the thickness of the phenol resin applied to the sleeve surface by the surface treatment was 2 μm.

On the other hand, using the above phenol resin, JIS
Prepare the first test piece specified in K7113,
When a tensile test was performed in accordance with IS K7113, the elongation at break was less than 3%.

Example 5 Carbon black Printix 35 was used as a conductive agent in a phenol resin for surface treatment.
A developing roller was prepared in the same manner as in Example 4, except that the surface treatment of the sleeve was performed by adding 20 phr (manufactured by Degussa). Observation of the fracture surface of this sleeve revealed that the thickness of the phenolic resin to which the carbon black was added to the surface of the sleeve by the surface treatment was 3 μm.
m.

On the other hand, a first type test piece specified in JIS K7113 was prepared using the phenol resin to which the carbon black was added, and a tensile test according to JIS K7113 was performed. 3
%. When the resistance value of this resin was measured, it was 104 Ωcm, and it was confirmed that the resin was rendered conductive by the addition of carbon.

Example 6 A developing roller was prepared in the same manner as in Example 3 except that the surface treatment of the sleeve by dipping was repeated several times, and the resin applied to the sleeve surface was thickened. When the fracture surface of this sleeve was observed, the thickness of the resin applied to the surface of the sleeve by the surface treatment was 20 μm.

Comparative Example 3 Soluble Copolymer Nylon CM8
A developing roller was prepared in the same manner as in Example 3, except that the surface treatment of the sleeve was performed using a resin solution of 000 (manufactured by Toray Industries, Ltd.) in methanol at a concentration of 15% by weight. Observation of the fracture surface of this sleeve revealed that the thickness of the nylon applied to the sleeve surface by the surface treatment was 5 μm.

On the other hand, a first type test piece specified in JIS K7113 was prepared using the above soluble copolymerized nylon, and a tensile test was performed in accordance with JIS K7113. The elongation at break was 100% or more. Met.

Comparative Example 4 A developing roller was prepared in the same manner as in Example 3 except that the surface treatment was not applied to the sleeve.

The following durability tests were performed on the developing rollers obtained in Examples 3 to 6 and Comparative Examples 3 and 4. The developing device shown in FIG. 5 was constructed using the developing rollers of Examples 3 to 6 and Comparative Examples 3 and 4, and this was incorporated into a laser beam printer to obtain five types of pitch patterns of 0.1 mm to 3 mm. Were continuously printed.
When the number of printed sheets reached 5,000, 15,000, and 40,000, respectively, the developing roller was taken out, and the roughness (JIS 10-point average roughness Rz) of the sleeve surface was measured. Further, a change in an image with an increase in the number of printed sheets was confirmed. Table 2 shows the results.

[0103]

[Table 2]

As is clear from Table 2, according to the developing rollers of Examples 3 to 6 according to the present invention, the roughness of the sleeve surface hardly changes even after long-term continuous use, and the developer is conveyed. No image deterioration due to defects or the like was observed even after printing 40,000 sheets. In particular, the rollers of Examples 3 to 5, in which the surface roughness (a) of the base material of the sleeve and the thickness (b) of the resin component on the surface are optimized, are excellent in developer transportability and have an image of good density. Was obtained with certainty. On the other hand, in the developing rollers of Comparative Examples 3 and 4, the surface roughness greatly changes as the number of printed sheets increases, and the image of the developing roller starts from around 10,000 sheets in Comparative Example 3 and from around 15,000 sheets in Comparative Example 4, respectively. Degradation, and in particular, the occurrence of ghosts became remarkable.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a magnet roller of the present invention.

FIG. 2 shows another example of the magnet roller of the present invention, wherein (A1) to (C1) are partial perspective views, and (A2) to (C).
2) is a partial sectional view.

3A and 3B are schematic cross-sectional views illustrating a manufacturing method of the present invention, wherein FIG. 3A shows a state during injection molding, and FIG.

FIG. 4 is a schematic view illustrating an example of a developing roller of the present invention.

FIG. 5 is a schematic view showing an example of the developing device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet main body part 2 Shaft part 3 Die 31 Upper mold 32 Lower mold 4 Eject pin 6 Sleeve 7 Magnet roller 8 Roller for toner application 9 Photosensitive drum (latent image holder) 10 Toner (developer) 11 Layering blade 12 Transfer part 13 Cleaning part 14 Cleaning blade

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eiji Eifuku 1-10-21-303, Yoshiyuki Fujisawa-shi, Kanagawa Prefecture (72) Inventor Kotaro Takebe 1-64-13, Sakura, Setagaya-ku, Tokyo (72) Inventor Taihei Goto 150-7-303, Kashio-cho, Totsuka-ku, Yokohama-shi, Kanagawa

Claims (23)

[Claims] 1. A magnet roller, wherein a magnet main body and a shaft protruding from both ends or one end of the magnet main body are integrally formed of a bonded magnet composition in which magnetic powder is dispersed in a resin binder. But,
Strontium / barium element ratio (Sr / Ba ratio) is 1
Magnet roller which is a ferrite of ~ 100. 2. The ferrite has an average particle diameter of 1.35.
BET specific surface area of 1.6 to 1.9 m ² / g at １．５1.5 μm
The magnet roller according to claim 1, wherein: 3. The resin binder has a number average molecular weight of 8
The nylon 6 of 000 to 10500.
The described magnet roller. 4. A plurality of magnetic poles in a magnet roller, wherein a magnet main body and a shaft protruding from both ends or one end of the magnet main body are integrally formed with a bonded magnet composition in which magnetic powder is dispersed in a resin binder. And a difference between the magnetic force of the high magnetic pole having the maximum magnetic force and the magnetic force of the low magnetic pole having the minimum magnetic force is 100 G or more. 5. The magnet roller according to claim 4, wherein the high magnetic pole having the maximum magnetic force is a developing pole. 6. A bonded magnet composition in which magnetic powder is dispersed in a resin binder is molded using a mold, and the bonded magnet composition is used to form a magnet main body and a shaft protruding from both ends or one end of the magnet main body. By integrally molding, the mold is divided and the magnet body portion is pushed by an eject pin to push off the magnet roller composed of the magnet body portion and the shaft portion from the mold. Method of manufacturing a magnet roller. 7. The method for manufacturing a magnet roller according to claim 6, wherein a tip end surface of the eject pin is a curved surface having substantially the same curvature as a curvature of an outer peripheral surface of the magnet main body. 8. A bonded magnet composition in which magnetic powder is dispersed in a resin binder is injected into a cavity of a mold in a molten state, and the bonded magnet composition is used to form a magnet main body and both ends or one end of the magnet main body. In a method of manufacturing a magnet roller for integrally molding a shaft portion protruding from a mold, a gate is formed on the mold corresponding to an outer peripheral surface portion or an end surface portion of the molded magnet main body portion or an outer peripheral surface portion of the shaft portion. A method for manufacturing a magnet roller, comprising: injecting and injecting the bonded magnet composition into a cavity of the mold through the gate. 9. An image forming apparatus comprising: a cylindrical sleeve rotatably disposed; and a magnet roller disposed inside the sleeve, and developing on an outer peripheral surface of the sleeve by a magnetic characteristic of the magnet roller. Forming a thin layer of the developer by carrying the developer, and in this state, the developer is caused to fly and supplied to the surface of the image forming body by the magnetic characteristics of the magnet roller in the vicinity of the image forming body. A developing roller for forming a visible image on the surface of the image forming body, wherein the magnet roller is the magnet roller according to any one of claims 1 to 3. 10. A developing device comprising: a cylindrical sleeve rotatably disposed; and a magnet roller disposed inside the sleeve, and developing on an outer peripheral surface of the sleeve by a magnetic characteristic of the magnet roller. Carrying a developer to form a thin layer of the developer, in this state, in the vicinity of the image forming body,
6. A developing roller for forming a visible image on the surface of the image forming body by supplying the developer by flying the surface of the image forming body according to the magnetic characteristics of the magnet roller, wherein the magnet roller comprises: A developing roller, which is the magnet roller according to 1. 11. A sleeve, which is rotatably disposed, and has a magnet roller disposed inside the sleeve, and develops on an outer peripheral surface of the sleeve by a magnetic characteristic of the magnet roller. Carrying a developer to form a thin layer of the developer, in this state, in the vicinity of the image forming body,
8. A developing roller for forming a visible image on the surface of the image forming body by flying and supplying the developer to the surface of the image forming body according to the magnetic characteristics of the magnet roller, wherein the magnet roller is provided. 6. A developing roller manufactured by the manufacturing method according to 1. 12. A developing device comprising: a cylindrical sleeve rotatably disposed; and a magnet roller disposed inside the sleeve, wherein a magnetic property of the magnet roller causes development on an outer peripheral surface of the sleeve. Carrying a developer to form a thin layer of the developer, in this state, in the vicinity of the image forming body,
9. A developing roller for forming a visible image on the surface of the image forming body by supplying the developer by flying the surface of the image forming body according to the magnetic characteristics of the magnet roller, wherein the magnet roller is configured as described in claim 8. A developing roller manufactured by a manufacturing method. 13. A developing device comprising: a cylindrical sleeve rotatably disposed; and a magnet roller disposed inside the sleeve, wherein a magnetic property of the magnet roller causes development on an outer peripheral surface of the sleeve. Carrying a developer to form a thin layer of the developer, in this state, in the vicinity of the image forming body,
In the developing roller for forming a visible image on the surface of the image forming body by flying and supplying the developer to the surface of the image forming body by the magnetic characteristics of the magnet roller, when the inner diameter of the sleeve is X mm The outer diameter of the magnet roller is (X-4) to (X-0.2) m
m. 14. A developer is carried on the outer peripheral surface of the developing roller by a magnetic characteristic of the magnet roller to form a thin layer of the developer. In the developing roller that forms a visible image on the surface of the image forming body by supplying the developer by flying over the surface of the image forming body, the elongation at break according to JIS K7113 is 10% on the surface portion. A developing roller having the following resin component. 15. When the JIS 10-point average roughness Rz of the surface of the base material forming the surface portion of the developing roller is a and the thickness of the resin component applied to the surface of the base material is b, 0.01
15. The developing roller according to claim 14, wherein a relationship of <b / a <2 is satisfied. 16. The method according to claim 16, wherein the resin component is a urea resin, a melamine resin, an alkyd resin, a modified alkyd resin, an oil-free alkyd resin, an acrylic resin, a silicone resin.
16. The developing roller according to claim 14, wherein the developing roller contains one or more selected from a phenol resin and a moisture-curable urethane resin. 17. A developing roller comprising: a cylindrical sleeve rotatably disposed; and a magnet roller disposed inside the sleeve, wherein the resin component is applied to a surface portion of the sleeve. Claim 14
17. The developing roller according to any one of claims 16 to 16. 18. The developer is carried on the surface of the latent image holding member by rotating while approaching the surface of the latent image holding member holding the electrostatic latent image on the surface while the developer is carried on the outer peripheral surface. A developing device comprising a developing roller for visualizing the electrostatic latent image by adhering to the electrostatic latent image, wherein the developing roller according to claim 9 is used as the developing roller. 19. The developer is carried on the surface of the latent image holding member by rotating while approaching the surface of the latent image holding member holding the electrostatic latent image on the surface while the developer is carried on the outer peripheral surface. A developing device comprising a developing roller for adhering the electrostatic latent image to visualize the electrostatic latent image, wherein the developing roller according to claim 10 is used as the developing roller. 20. The developer is carried on the surface of the latent image holding member by rotating while approaching the surface of the latent image holding member holding the electrostatic latent image on the surface while the developer is carried on the outer peripheral surface. A developing device comprising: a developing roller that adheres to an electrostatic latent image to visualize the electrostatic latent image, wherein the developing roller according to claim 11 is used as the developing roller. 21. The developer is carried on the surface of the latent image holding member by rotating while approaching the surface of the latent image holding member holding the electrostatic latent image on the surface while the developer is carried on the outer peripheral surface. 13. A developing device comprising a developing roller for adhering to an electrostatic latent image to visualize the electrostatic latent image, wherein the developing roller according to claim 12 is used as the developing roller. 22. When the developer is carried on the outer peripheral surface, the developer is brought close to the surface of the latent image holding member holding the electrostatic latent image on the surface, and the developer rotates the electrostatic latent image on the surface of the latent image holding member. 14. A developing device comprising a developing roller that adheres to an electrostatic latent image to visualize the electrostatic latent image, wherein the developing roller according to claim 13 is used as the developing roller. 23. The developer is carried on the surface of the latent image holding member by rotating while approaching the surface of the latent image holding member holding the electrostatic latent image on the surface while the developer is carried on the outer peripheral surface. 18. A developing device comprising a developing roller for adhering the electrostatic latent image to visualize the electrostatic latent image, wherein the developing roller according to any one of claims 14 to 17 is used as the developing roller. A developing device.