JP2989092B2 - Method for regenerating Mn-Zn ferrite carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for recovering used Mn.
The present invention relates to a method for regenerating a Zn-based ferrite carrier by performing a two-stage heat treatment. This method is a technique of recovering and reusing a ferrite carrier used as a developer in an electrophotographic printer or the like.

[0002]

2. Description of the Related Art A ferrite carrier used as a developer in an electrophotographic printer or the like, when used to some extent, causes adhesion of toner and peeling of a coating resin.
They are replaced and collected because the print quality deteriorates.

As a method for regenerating a recovered ferrite carrier, there is a technique disclosed in Japanese Patent Application Laid-Open No. 63-212945. Here, the first heating operation for heating and removing the attached matter and the second heating operation for adjusting the electric resistance changed by the first heating operation are performed. The conditions of the first heating operation are approximately 200 to 900 ° C., preferably 400 to 800 ° C. in an oxidizing atmosphere, and the conditions of the second heating operation are ± 30 ° C. with respect to the firing conditions at the time of ferrite particle production.
0 ° C., preferably ± 200 ° C. In the embodiment,
In each case, the first heating operation is performed at 700 ° C., and the second heating operation is performed at 1100 ° C.

[0004]

The ferrite carrier is made of Mn-Zn because of its low resistance, high saturation magnetization and relatively close properties to magnetite.
A system is used. In the case of this Mn-Zn based ferrite carrier, usually, Fe ₂ O ₃
The amount is more than stoichiometric. Therefore, when heat treatment is performed in a high-temperature oxidizing atmosphere as in the related art, a hetero-phase is precipitated and magnetic properties are deteriorated.

An object of the present invention is to provide a method for regenerating a recovered carrier of Mn-Zn ferrite so that it can be reused without significantly deteriorating magnetic properties.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a primary heat treatment is performed on a recovered used Mn-Zn ferrite carrier in air at a temperature higher than a temperature at which adhered toner and coating resin can be removed and lower than 500 ° C. This is a method for regenerating a Mn-Zn ferrite carrier that is subjected to a secondary heat treatment in a nitrogen atmosphere at 400 to 600 ° C., cooled as it is in a nitrogen atmosphere, and coated again with a resin for characteristic adjustment.
Here, the primary heat treatment is preferably performed at 400 to 450 ° C., and the secondary heat treatment is preferably performed at 450 to 550 ° C. in a nitrogen atmosphere. In the production of a Mn-Zn ferrite carrier (new), the firing temperature is usually from 1250 to 1
300 ° C. Therefore, the primary and secondary heat treatment temperatures of the present invention are both considerably lower than the firing temperature.

[0007]

The Mn-Zn ferrite is easily oxidized and the oxidation causes a hematite layer to be formed on the surface to deteriorate magnetic properties. Completely remove the resin,
Moreover, the oxidation reaction of the Mn-Zn-based ferrite carrier can be suppressed, and the deterioration of the magnetic properties can be reduced as much as possible. Then, the secondary heat treatment is performed in a nitrogen atmosphere at 400 to 600 ° C.
By adjusting the temperature to a low temperature, the required electromagnetic characteristics are adjusted, and the deterioration of the magnetic characteristics is suppressed. In some cases, the magnetic characteristics deteriorated by the primary heat treatment are restored to near the original state.

[0008] The primary heat treatment is performed in the air to remove the coating resin. The temperature at which the coating resin scatters can be determined by thermogravimetric analysis or the like. According to the analysis result, although it depends on the type of the coating resin used, it can be usually removed by heating to about 370 ° C. in air. The primary heat treatment temperature was set at less than 500 ° C. and the secondary heat treatment temperature was set at 400 to 600 ° C. From the characteristic distribution diagram of the heating temperature-saturation magnetization σs, the characteristics of the reproduced carrier are significantly larger than those of the new carrier. This is so as not to decrease.

[0009]

FIG. 1 shows a reproduction processing flow of the present invention. First, the Mn-Zn-based ferrite recovery carrier 10 was subjected to a primary heat treatment at 450 ° C. in air to remove deposits on the carrier surface, thereby obtaining a primary heat-treated product 12. The saturation magnetization of the primary heat-treated product 12 was 83.18 emu / g.
The original Mn-Zn ferrite carrier (new)
Has a saturation magnetization of 86.65 emu / g. Next, a secondary heat treatment was performed in order to adjust electric resistance that was deteriorated by the primary heat treatment. In that case, in order to prevent the saturation magnetization from deteriorating further, it was performed at 500 ° C. in a 100% nitrogen atmosphere, and was cooled as it was. The resulting secondary heat-treated product 14 had a saturation magnetization of 85.78 emu / g. This secondary heat-treated product 14 was coated with a resin to obtain a recycled carrier 16. This regenerated carrier had the same electrical resistance as a new carrier (new) and had good printing results.

On the basis of the above results, an experiment was carried out to manufacture a reproduced carrier by changing the primary heat treatment temperature and the secondary heat treatment temperature, and the saturation magnetization was measured. First, in addition to the above 450 ° C., the primary heat treatment temperature was set to 500 ° C. and 60 ° C.
At a temperature of 0 ° C., a primary heat-treated product was produced. Their saturation magnetization is as shown in Table 1. It can be seen that the higher the heat treatment temperature, the more the saturation magnetization deteriorates.

[0011]

[Table 1]

Next, for the primary heat-treated product, 300
A secondary heat-treated product was produced by changing the secondary heat treatment temperature in the range of -700 ° C. Table 2 shows their saturation magnetization (emu / g). It can be seen that the saturation magnetization is greatly deteriorated when the secondary heat treatment temperature is too high or too low.

[0013]

[Table 2]

FIG. 2 shows the relationship between the primary and secondary heat treatment temperatures and the saturation magnetization σs through various experiments. This shows that the primary heat treatment temperature is set on the horizontal axis and the secondary heat treatment temperature is set on the vertical axis, and the condition range and the degree of saturation magnetization are shown. As a result, the primary heat treatment temperature is reduced to 5
It can be seen that when the secondary heat treatment temperature is less than 00 ° C. and the secondary heat treatment temperature is 400 to 600 ° C., the saturation magnetization becomes approximately 80 emu / g or more. Most preferably, the primary heat treatment temperature is about 450 ° C. and the secondary heat treatment temperature is about 500 ° C. Under these optimum conditions, the saturation magnetization slightly reduced by the primary heat treatment is recovered by the secondary heat treatment, and exhibits extremely good characteristics almost equivalent to a new Mn-Zn ferrite carrier.

[0015]

According to the present invention, as described above, the primary heat treatment is performed in air at less than 500 ° C.
Since it is a regeneration method in which secondary heat treatment is performed in a nitrogen atmosphere at 600 ° C., a recovery carrier of Mn—Zn-based ferrite is
It is possible to regenerate the carrier so that it can be used again without any problem in the performance as a carrier, with no reduction in the saturation magnetization within an allowable limit without precipitation of a heterogeneous phase.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a reproduction processing flow according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between primary and secondary heat treatment temperatures and saturation magnetization.

[Explanation of symbols]

 Reference Signs List 10 recovery carrier 12 primary heat-treated product 14 secondary heat-treated product 16 recycled carrier

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/10

Claims (2)

(57) [Claims] 1. A primary heat treatment of the recovered used Mn—Zn-based ferrite carrier in air at a temperature higher than a temperature at which the attached toner and the coating resin can be removed and lower than 500 ° C. , 400~600 ℃ of nitrogen
A secondary heat treatment in an elementary atmosphere, cooling as it is in a nitrogen atmosphere, and coating with a resin again.
A method for regenerating a Zn-based ferrite carrier. 2. The method according to claim 1, wherein the first heat treatment is performed at 400 to 450 ° C., and the second heat treatment is performed at 450 to 550 ° C. in a nitrogen atmosphere.