JPH05100565A - Developing roll - Google Patents

Abstract

PURPOSE:To suppress the fluctuations in the electric resistance over the entire part of the developing roll to a lower level even if there is unequal coating of an adhesive by constituting a resin magnet layer and a conductive base body of an adhesive layer contg. 0.2 to 5wt.% carboxyl group. CONSTITUTION:This developing roll has the conductive base body 1 consisting of a stainless steel, etc., the resin magnet 3 and the adhesive layer 2a contg. 0.2 to 5wt.% carboxyl group. The electric resistance of the conductive base body 1 and the surface of the resin magnet layer 3 of the developing roll constituted in such a manner is given by the sum of the electric resistance of the adhesive layer 2a and the electric resistance of the resin magnet layer 3. The adhesive contg. 0.2 to 5wt.% carboxyl group is used in order to decrease the electric resistance of the adhesive layer 2a. The electric resistance of the adhesive layer is decreased in this way and the difference in the electric resistance between the adhesive and the resin magnet layer is decreased. The developing roll which can suppress the fluctuations in the electric resistance in spite of the presence of the unequal coating is thus obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a facsimile,
Further, the present invention relates to a developing roll used in an electrophotographic developing device such as a laser printer, and more specifically, to a developing roll for a direct contact electrophotographic developing method which does not use a sleeve in which the developer directly contacts the surface of the developing roll. .

[0002]

2. Description of the Related Art In recent years, a sleeveless developing roll has been used in one system of an electrophotographic developing apparatus such as a copying machine or a facsimile. This product usually has an adhesive layer formed on a columnar or cylindrical conductive substrate, on which a resin magnet layer is arranged as a magnetic dielectric, and its surface has a fine surface finish. There are many.

FIG. 2 is a sectional view of a conventional developing roll. In FIG. 2, 1 is a conductive substrate, 2 is an adhesive layer, and 3 is a resin magnet layer. As shown in FIG. 3, such a developing roll applies a current from the conductive substrate 1 in the radial direction to give an electric potential to the surface of the resin magnet layer 3 and a difference between the surface of the resin magnet layer 3 and the electric potential on the photosensitive drum. To convey the toner onto the photosensitive drum. Since the developing roll is an application of cylindrical resistance, it is necessary that the resin magnet layer has no variation in electric resistance. Therefore, it is possible to improve the kneading state of the resin magnet layer and reduce the variation of constituent raw materials as compared with the conventional case. It has been understood to be the most important issue for stabilizing the characteristics of the roll.

[0004]

However, in the above conventional structure, the electric resistance of the adhesive layer is significantly higher than the electric resistance of the resin magnet layer, so that the electric resistance of the adhesive layer is the electric resistance of the entire developing roll. However, even if the quality of the resin magnet layer is good, there is a problem that the electric resistance varies greatly if there is uneven coating of the adhesive. Also, since the adherend is a resin magnet layer and a substantially conductive resin, which is a conductive substrate, and a metal, it is necessary to use a commonly used nitrile rubber-based or acrylic-based material to bond them with sufficient adhesive strength. The adhesive layer needs to have a certain thickness, but when the adhesive layer is thick, there is a problem that uneven coating is likely to occur and variation in electric resistance is likely to occur.

The present invention is intended to solve the above-mentioned conventional problems, and by using an adhesive having a small electric resistance as an adhesive for adhering the resin magnet layer and the conductive substrate, the adhesive layer and the resin magnet are used. It reduces the difference in the electrical resistance of the layers, which means that even if the adhesive has uneven coating,
An object of the present invention is to provide a developing roll capable of suppressing variations in the electric resistance of the entire developing roll to be small.

[0006]

The developing roll of the present invention which has achieved this object has a constitution in which a resin magnet layer and a conductive substrate are adhered by an adhesive layer containing 0.2 to 5 wt% of a carboxyl group. is doing.

[0007]

By using the adhesive containing 0.2 to 5 wt% of the carboxyl group, the electric resistance of the adhesive layer is reduced, and the difference in electric resistance between the adhesive and the resin magnet layer can be reduced. It is possible to obtain a developing roll that can suppress variations in electric resistance even if there is uneven coating of the adhesive.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a schematic structure of a developing roll of the present invention, in which 1 is a conductive substrate such as stainless steel and 3 is a resin magnet layer. And 2a is an adhesive layer containing 0.2 to 5 wt% of a carboxyl group in the main component. In the developing roll configured in this way,
Electric resistance R between the conductive substrate 1 and the surface of the resin magnet layer 3
Is given by the sum of the electric resistance of the adhesive layer 2a and the electric resistance of the resin magnet layer 3 as shown in Equation 1.

[0009]

[Equation 1]

As shown in this equation, if the electric resistance of the adhesive layer 2a can be made small and the difference in electric resistance between the adhesive layer 2a and the resin magnet layer 3 can be made small, the adhesive layer 2a occupies the entire electric resistance R. The contribution of the electric resistance is also reduced, and the influence of uneven coating of the adhesive on the electric resistance of the entire developing roll is also reduced. As a result, a developing roll having a small variation in the electric resistance can be obtained. In the present invention, in order to reduce the electric resistance of the adhesive layer 2a, 0.2% is added to the main component.
An adhesive containing ˜5 wt% carboxyl groups was used.

Next, the result of the variation measurement of the electrical characteristics of the example of the present invention and the comparative example performed for confirming the effect of the present invention will be described. A thermoplastic resin obtained by copolymerizing 85% by weight of vinyl chloride monomer, 13% by weight of vinyl acetate monomer and 2% by weight of fumaric acid which is one kind of unsaturated dicarboxylic acid is dissolved in methyl ethyl ketone at a concentration of 5% by weight,
This was an adhesive solution. This is spray-sprayed on a notched stainless steel shaft and dried at 50 ° C for 20 minutes,
An adhesive layer having a thickness of 10 μm from the center of the shaft to one end and a thickness of 100 μm from the center of the shaft to the other end was formed to intentionally form a difference in thickness of the adhesive layers. The resin magnet layer was composed of 70% by weight of chlorinated polyethylene, 29.5% by weight of ethylene / vinyl acetate copolymer, and 0.5% by weight of phenolic antioxidant, and 40% by volume of a resin mixture and 60% by volume of Ba ferrite. Was mixed with a mixer and then kneaded with a hot roll mill at 120 ° C. to obtain a plastic resin ferrite kneaded product for molding, which was formed into a thickness of 1 mm from the surface of the shaft by an extruder equipped with a crosshead die on the shaft. It was produced by coating molding at 140 ° C. With respect to the developing rolls of the examples of the present invention thus produced, measurement points were taken in regions of the surface of the molded article having different adhesive thicknesses, and the apparent volume resistivity was measured at each value. The results are shown in Table 1. Further, except that an adhesive containing no fumaric acid was used, a developing roll having substantially the same components and configurations as those of the above-described examples was prepared as a comparative example, and also for this, similar to the above-mentioned examples, an apparent volume at a predetermined value was also obtained. The specific resistance was measured. The results are shown in Table 1.

[0012]

[Table 1]

As is apparent from Table 1, according to the developing roll of this embodiment, the difference in the thickness of the adhesive layer has a small effect on the variation in the electric resistance of the entire developing roll, which is caused by the uneven coating of the adhesive. It can be seen that the variation in the electric resistance caused by this can be reduced.

Although the content of the carboxyl group to be introduced is 4 wt% in the above embodiment, it is 0.2 wt% to 5 wt%.
It may be in the range of wt%. If the amount is less than this, it cannot be expected to contribute to the improvement of metal adhesion. Preferably 0.5
It is more than wt%. On the other hand, if it is 5 wt% or more, complex formation with a metal salt or the like inevitably present in the dielectric body is likely to occur, and the electrical characteristics fluctuate based on this, which is not preferable. It is more preferably 3 wt% or less.

The carboxyl groups are provided for copolymerization in the main resin in the form of unsaturated dicarboxylic acids. As the unsaturated dicarboxylic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid and the like can be used. Since itaconic acid, mesaconic acid, and citraconic acid have an alkyl group at the base of the carboxyl group, the polarization of the carboxyl group itself is weak, and the conductivity is slightly inferior to that of fumaric acid or maleic acid. Therefore, fumaric acid and maleic acid are preferable. Maleic acid having a carboxyl group at the cis position is more preferable because it has good metal adhesion.

Although the type of adhesive is thermoplastic in the above embodiment, it may be thermosetting or any other widely used adhesive, and may be appropriately selected from these depending on the purpose and manufacturing method. You can use it. A pressure sensitive adhesive can also be used if sufficient adhesive strength is obtained. It is preferably thermoplastic. This is because it is suitable for simultaneous adhesion in the coating molding step of the developing roll. Further, it is preferable from the standpoint of processability to use an adhesive containing an inferior amount of vinyl acetate or the like having a low softening point. Although the spraying method was used as the coating method in the above-mentioned examples, ordinary methods such as a coating method, a dipping method, and a transfer method can be used.

The average thickness of the adhesive is preferably 100 μm or less. If the average thickness of the adhesive exceeds 100 μm, not only the electric resistance value of the developing roll but also the electrical properties such as the relative dielectric constant are excessively affected, the adhesive strength is weakened, and there is a problem that the coating process is troublesome. Furthermore, uneven coating is likely to occur, which is not preferable. In order to easily realize a thin coating, it is preferable to apply it in a solvent diluted state. The emulsion type is not preferable because of the presence of foreign substances such as dispersants and emulsifiers and the presence of pinholes.

The resin magnet means a permanent magnet powder filled in a thermoplastic resin, a thermosetting resin or rubber, and barium ferrite, strontium ferrite or the like can be used as the magnet powder used in the resin magnet of the present invention. These may be isotropic or anisotropic. This may be surface-treated with a silane-based or titanate-based coupling agent. As the binder, those containing a thermoplastic resin, unvulcanized rubber, vulcanized rubber, etc. as a main component and containing a plasticizer, a stabilizer, a lubricant, a vulcanizing agent or a crosslinking agent, a filler, etc. can be used. It is preferable to use a thermoplastic resin. Those requiring a vulcanization step or a crosslinking step are not preferable because the electrical characteristics of the molded product vary depending on the progress of the reaction.

As the method for forming the magnetic dielectric layer on the above-mentioned conductive substrate, various ordinary methods are appropriately selected.
For example, there is a method in which a rubber magnet sheet is wound around a substrate and pressure-bonded, and a more preferable method is a conductive substrate surface coated with an adhesive by a thermoplastic resin magnet material by an injection molding method or an extrusion molding method. The method of coating and molding can be exemplified.

[0020]

As described above, according to the present invention, the main component of the adhesive layer of the dielectric developing roll contains 0.2 to 5 wt% of carboxyl group, so that the electric resistance of the adhesive layer is reduced and the adhesive agent Since the difference in electrical resistance between the resin layer and the resin magnet layer has been reduced, it is possible to minimize variations in the electrical resistance of the entire developing roll caused by uneven coating of the adhesive, and the occurrence of image defects is extremely low. A developing roll can be provided. In addition, it is suitable for mass production because the allowable range of uneven coating of adhesive can be expanded compared to conventional developing rolls.
It can also contribute to the improvement of productivity.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing the outline of a developing roll of the present invention.

FIG. 2 is an explanatory sectional view showing the outline of a conventional developing roll.

FIG. 3 is an explanatory cross-sectional view showing an operation mode of a current passing through a developing roll.

[Explanation of symbols]

 1 Conductive Substrate 2 Adhesive Layer 2a Adhesive Layer 3 Resin Magnet Layer

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[Procedure amendment]

[Submission date] August 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Paragraph number 0006

[Correction method] Change

[Correction content]

[0006]

The developing roll of the present invention which has achieved this object has a constitution in which a resin magnet layer and a conductive substrate are adhered by an adhesive layer containing 0.2 to 5 wt% of a carboxyl group- containing compound. have.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] Paragraph number 0007

[Correction method] Change

[Correction content]

[0007]

By using the adhesive containing 0.2 to 5 wt% of the carboxyl group- containing compound, the electric resistance of the adhesive layer is reduced, and the difference between the electric resistance of the adhesive and the resin magnet layer is reduced. It is possible to obtain a developing roll capable of suppressing variations in electric resistance even if there is uneven coating of the adhesive.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Paragraph number 0008

[Correction method] Change

[Correction content]

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a schematic structure of a developing roll of the present invention, in which 1 is a conductive substrate such as stainless steel and 3 is a resin magnet layer. 2a is an adhesive layer containing 0.2 to 5 wt% of a carboxyl group- containing compound in the main component. In the developing roll configured as described above, the electric resistance R between the surface of the conductive substrate 1 and the surface of the resin magnet layer 3 is the sum of the electric resistance of the adhesive layer 2a and the electric resistance of the resin magnet layer 3 as shown in Formula 1. Given in.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] Paragraph number 0010

[Correction method] Change

[Correction content]

As shown in this equation, if the electric resistance of the adhesive layer 2a can be made small and the difference in electric resistance between the adhesive layer 2a and the resin magnet layer 3 can be made small, the adhesive layer 2a occupies the entire electric resistance R. The contribution of the electric resistance is also reduced, and the influence of uneven coating of the adhesive on the electric resistance of the entire developing roll is also reduced. As a result, a developing roll having a small variation in the electric resistance can be obtained. In the present invention, in order to reduce the electric resistance of the adhesive layer 2a, 0.2% is added to the main component.
An adhesive containing ˜5 wt% of a carboxyl group- containing compound was used.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] Paragraph number 0014

[Correction method] Change

[Correction content]

Although the content of the carboxyl group- containing compound to be introduced is 4 wt% in the above embodiment, it is 0.2
It may be in the range of 5 wt% to 5 wt%. If the amount is less than this, it cannot be expected to contribute to the improvement of metal adhesion. It is preferably 0.5 wt% or more. On the other hand, if it is 5 wt% or more, complex formation with a metal salt or the like inevitably present in the dielectric body is likely to occur, and the electrical characteristics fluctuate based on this, which is not preferable. It is more preferably 3 wt% or less.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] Paragraph number 0020

[Correction method] Change

[Correction content]

[0020]

As described above, according to the present invention, the main component of the adhesive layer of the dielectric developing roll is 0.2 to 5 wt% of carboxyl group.
By including the contained compound, the electrical resistance of the adhesive layer was reduced and the electrical resistance difference between the adhesive layer and the resin magnet layer was reduced. It is possible to minimize the variation in resistance, and it is possible to provide an excellent developing roll with extremely few image defects. Further, since the allowable range of uneven coating of the adhesive can be expanded as compared with the conventional developing roll, it is suitable for mass production and can contribute to improvement of productivity.

Claims (1)

[Claims] 1. The resin magnet layer and the conductive substrate are 0.2
A developing roll bonded with an adhesive layer containing a carboxyl group of ˜5 wt%.