JPH10116716A - Oxide magnetic material and carrier using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently manufacture carriers using an oxide magnetic material, by a method wherein an Mn compound and an Li compound in a specific range are mixed into hematite and granulated, and the granulated matter is sintered at a temperature in a specific range with low oxygen, etc., and magnetization and resistivity characteristics of a specific value or more and a coercive force of a specific value or less are set. SOLUTION: In an arrangement step 1, an Mn compound 31 to 65mol%, an Li compound 5 to 20mol% and the remaining hematite are arranged, and the arranged matter obtained in the arrangement step 1 is mixed and pulverized by a mixture step 2 and a powdering step 3 in a granulating step 4, and the powder is granulated. This granulated matter is sintered at 1150 to 1300 deg.C during low oxygen or during an air, whereby an oxide magnetic material set to be magnetization 35emu or more, a coercive force 100e or less and resistivity characteristics 5000V/cm or more is manufactured. The oxide magnetic material is coated with resin a coating step 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an oxide magnetic material and a carrier using the same. The oxide magnetic material used for the carrier, which is a toner carrier used in copiers, printers, etc., has sufficient magnetization and resistivity characteristics in a clean carrier containing no heavy metal due to problems such as concerns about environmental pollution in recent years. Things are desired.

[0002]

2. Description of the Related Art When used as a developer for a printer or the like, an oxide magnetic material needs to have a certain degree of magnetization under a practical magnetic field and to have a certain degree of resistivity characteristics.

[0003]

Conventionally, when an oxide magnetic material is used as a developer in a printer or the like, a low magnetization under a practical magnetic field generally causes the carrier to adhere to a photosensitive member. .

Further, the characteristic of magnetization is very sensitive to the atmosphere, and is affected by the oxygen concentration or the air introduction temperature during processing such as resistance adjustment, causing problems such as a decrease in magnetization.

Further, there is no carrier called a clean carrier that simultaneously satisfies the high magnetization and high resistivity characteristics of the core itself. In some cases, Mg-based or Ca-based carriers cannot be used depending on the device due to resistance, coercive force, and magnetization characteristics. This is particularly caused by the problem of coercive force, and has been remarkably caused in the Ca-based material when atmosphere sintering or resistance treatment is performed for the purpose of increasing the resistance of the core itself.

[0006] The present invention solves these problems,
With the object of mixing an Mn compound and a Li compound into hematite and firing in low oxygen or air, the purpose is to realize an oxide magnetic material having good magnetization, resistivity characteristics and coercive force and to manufacture a carrier using the same. I have.

[0007]

Means for solving the problem will be described with reference to FIG. In FIG. 1, the blending step 1 comprises 31 to 65 mol% of a Mn compound, a Li compound 5
This is a step of blending about 20 mol% and the balance of hematite.

The granulating step 4 is a step of granulating the mixed powder. In the firing step 5, the granulated material is
It is fired in low oxygen or air at 00 ° C.

The coating step 7 is a step of coating the oxide magnetic material with a resin to generate a carrier. Next, a manufacturing method will be described.

In the blending step 1, 31 to 65 mol% of the Mn compound, 5 to 20 mol% of the Li compound and the balance of hematite are blended, and the powder blended and mixed in the granulating step 4 is granulated. The granulated material is calcined in low oxygen or air at 1150 to 1300 ° C. to produce an oxide magnetic material.

In the coating step 7, the oxide magnetic material is coated with a resin to manufacture a carrier. Therefore, it is possible to mix an Mn compound and a Li compound into hematite and fire it in low oxygen or air to produce an oxide magnetic material having good magnetization, resistivity characteristics and coercive force, and a carrier using the same. Become.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment and operation of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 is a block diagram showing an embodiment of the present invention.
In FIG. 1, the compounding step 1 includes the Mn compounds 31 to 6
In this step, 5 mol%, 5 to 20 mol% of a Li compound and the balance of hematite are blended.

In the mixing step 2, a liquid substance or powder containing -CC- or -C = C- in a molecule is added to a mixed powder obtained by mixing the Mn compound, the Li compound and hematite mixed in the mixing step 1. 0.1-4.0 wt of substance
% Mixing process.

The pulverizing step 3 is a step of wet-pulverizing the mixture obtained in the mixing step 2 with an attrition mill to prepare a slurry having a mixed powder concentration of about 50% by weight. The granulation step 4 is a step for producing spherical granules. here,
After the slurry is stirred for 1 hour with an attritor, it is dried with hot air using a spray dryer to form spherical granules.

In the calcination step 5, the granules obtained in the granulation step 4 are subjected to a heat treatment in a low oxygen atmosphere or in air at a temperature in the range of 1150 to 1300 ° C. for 2 hours to form a magnetic phase having a spinel structure and a non-magnetic phase. This is a step of forming a powder mixed with a magnetic phase.

In the sieving step 6, the baked and sized powder is sieved with a predetermined sieve. Here, for example,
The powder sieved with a 100 μm sieve is used as a product of the oxide magnetic material.

The coating step 7 is a step of coating the oxide magnetic material sieved in the sieving step 6 with a resin. Here, a fluoroacrylic resin was dissolved in a toluene solvent, the carrier was coated on the core material at 1.0 wt% using a fluidized bed, and dried by heating at 100 ° C. for 2 hours to obtain a coated carrier.

As described above, the main composition of iron oxide, Mn compound and Li compound is granulated with a predetermined composition.
By performing the firing in an air atmosphere from the beginning, the oxide magnetic material having a magnetization of 35 emu / g or more under a practical magnetic field and having no dielectric breakdown even when the electric field characteristic of resistivity is 5000 V / cm is obtained. Could be manufactured. Carriers in the two components of iron oxide and Mn compound can be easily conceived from the region of conventional ferrite and the like,
By mixing the Li compound therein, firing at a relatively lower temperature than that of conventional ferrite became possible.

The coercive force of the Mg-based material, which has been considered to be lower than that of the conventional Ca-based material, is about 20 to 30 Oe after the resistance treatment. It is less than 10 Oe (see FIG. 2 described later).

FIG. 2 shows an experimental example of the present invention. this is,
₃₀ to 65 mol% of Fe as a main component in terms of Fe ₂ O ₃ ;
Mn is 50 to 70 mol% in terms of MnO, and Li is Li ₂ O
8-30 mol% in conversion, polyvinyl alcohol 2.0w
After adding t%, the mixture was mixed with water to obtain a slurry having a powder concentration of 50% by weight, stirred for 1 hour with an attritor, and then granulated with a spray drier. Thereafter, the oxygen concentration (0 to 21% O ₂₎
In an electric furnace while controlling the oxygen concentration at a constant
Calcination was performed at 0 ° C. for 2 hours to obtain an oxide magnetic material. FIG. 3A shows a heating pattern. VSM embedded with the manufactured oxide magnetic material in a sample resin holder with a diameter of 6 mm
(Vibration magnetometer) 1 kOe magnetic characteristics (maximum magnetization σ)
s) was measured (see FIG. 3 (c)). In addition, the static resistivity and the like were measured using a jig as shown in FIG. The electrode size is circular and 5 mm in diameter.

Next, the experimental example of FIG. 2 will be described. Examples 1 to 5 show experimental examples in which the magnetization, coercive force, and resistivity characteristics are all good. Where F
The upper limit of e ₂ O ₃ is 49.0 mol%, and the lower limit of Fe ₂ O ₃ is 30.0 mol%. At this time, the minimum value of the magnetization is 49 emu, the maximum value of the coercive force is 8.0 Oe, and the minimum value of the resistivity characteristic is 5000 V / cm, and the magnetization is 35 emu / g which is a guideline for judging that the magnetic characteristics are good. ,
This corresponds to a coercive force of 10 Oe or less and a resistivity characteristic of 5000 V / cm or more, and is determined to have good magnetic characteristics.

Is an upper limit of 65.0 mol% of MnO,
Is the lower limit of 31.0 mol% of MnO. In this case, the minimum value of the magnetization is 46 emu / g, the maximum value of the coercive force is 7.0 Oe, and the minimum value of the resistivity characteristic is 5000 V / c.
m, the magnetization is 35 emu / g, the coercive force is 10 Oe or less, and the resistivity is 5
000 V / cm or more, and is judged to have good magnetic properties.

The upper limit of Li ₂ CO ₃ is 20.0 mol%, and the lower limit of Li ₂ CO ₃ is 5.0 mol%. In this case, the minimum value of the magnetization is 50 emu / g, the maximum value of the coercive force is 6.5 Oe, and the minimum value of the resistivity characteristic is 500 emu / g.
0 V / cm, all of which correspond to a magnetization of 35 emu / g, a coercive force of 10 Oe or less, and a resistivity characteristic of 5000 V / cm or more, which are criteria for judging that magnetic properties are good, and are judged to have good magnetic properties.

In Comparative Examples 1 to 4, the portions marked with “x” in the magnetization and coercive force are portions that do not correspond to magnetization of 35 emu / g and coercive force of 10 Oe or less, which are guidelines for judging that magnetic properties are good.

As can be seen from the above description, from the results of the experiment shown in FIG. 2, 30 to 49 mol% of Fe ₂ O ₃ .31.0 to 65.0 mol% of MnO. 5.0 of Li ₂ CO _3. It has been found that an oxide magnetic material having good magnetization, coercive force, and resistivity characteristics can be obtained when the content is in the range of ２20.0 mol%.

FIG. 3 shows an explanatory diagram of the present invention. FIG. 3A shows a heating temperature characteristic during sintering. This is because the sintering is carried out at a temperature rising rate of 200 ° C./H, the sintering temperature is kept at, for example, 1200 ° C. for 2 hours, and then the temperature is lowered by 200 ° C./H. At that time, the atmosphere control is stopped when a predetermined temperature is reached. Here, the atmosphere control is 21% O ₂ as shown in the figure.
(Air).

FIG. 3B schematically shows how the static resistivity is measured. Applying a voltage between the electrodes,
The current flowing at that time is measured, and the resistivity R
(Ω · cm) is calculated. B. D. The electric field strength is
When the voltage applied between the electrodes is gradually increased, the electric current suddenly increases, and the electric field strength which causes a breakdown (BD) is measured, and the value (V / cm) at that time is measured. Represent. In this example, the electrode size is circular and the diameter is 5 mm.
The sample (oxide magnetic material) is placed in the container (1), a constant voltage V is applied between the electrodes on both sides, the current I flowing at that time is measured, and the measured value is substituted into the formula shown in the figure to determine the resistivity.

The B.V. of the oxide magnetic material obtained as described above was used. D. Is the resistivity characteristic (BD) in the right column of FIG. FIG. 3C is an explanatory diagram of the magnetization (saturated magnetization) of the present invention. This is an explanatory diagram when measuring the magnetization in FIG. The horizontal axis represents the intensity H Oe of the applied magnetic field, and the vertical axis represents the magnetization intensity Memu at that time. The vibrating magnetometer measures a magnetization strength Msemu of a powder in which magnetite and a non-magnetic phase are mixed at that time in a state where a magnetic field of, for example, 1 kOe is applied as shown in the figure. Then, the saturation magnetization is determined by the following equation: δs = Ms / (weight of powder) [emu / g] (1) The magnetization emu / g shown in FIG. 2 is obtained by the equation (1).

[0030]

As described above, according to the present invention,
An Mn compound and a Li compound are mixed in hematite and calcined in low oxygen or air to produce an oxide magnetic material having good magnetization, resistivity characteristics and coercive force, and a carrier using the same. Was. By suppressing iron oxide, which is the main composition, to an appropriate amount, Fe ₃ O ₄ → F when firing in air (or in low oxygen).
By suppressing e ₂ O ₃ , suppressing the accompanying decrease in magnetization, and adding an appropriate amount of a Li compound, predetermined magnetization control and resistivity characteristics can be obtained. Further, it has become possible to manufacture an oxide magnetic material having good characteristics in a very simple process without performing the resistance treatment which has been performed as a conventional resistivity adjustment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention.

FIG. 2 is an experimental example of the present invention.

FIG. 3 is an explanatory diagram of the present invention.

[Explanation of symbols]

 1: compounding step 2: mixing step 3: pulverizing step 4: granulating step 5: firing step 6: sieving step 7: coating step

Claims (3)

[Claims] 1. A mixture of 31 to 65 mol% of a Mn compound, 5 to 20 mol% of a Li compound and the balance of hematite is granulated, and the granulated material is fired at 1150 to 1300 ° C. to maintain a magnetization of 35 emu or more. An oxide magnetic material having a magnetic force of 10 Oe or less and a resistivity characteristic of 5000 V / cm or more. 2. The oxide magnetic material according to claim 1, wherein said firing is performed in low oxygen or air. 3. A carrier coated with the oxide magnetic material produced according to claim 1 or 2.