JPH10116717A - 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, etc., in a specific range is mixed into hematite and granulated, and the granulated matter is sintered with low oxygen or in an air, 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 50 to 65mol%, a Ca compound 0 to 2.0wt.% when converted into Ca, an Si compound 0 to 3.0wt.% when converted into Si, and the remaining hematite are arranged, and next, the arranged matter obtained in the arrangement step 1 is mixed and pulverized by a mixture step 2 and a pulverizing step 3 in a granulating step 4, and the powder is granulated. This granulated matter is sintered during low oxygen or during an air in a calcination step 5, 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 in 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,
It is an object of the present invention to realize an oxide magnetic material having good magnetization, resistivity characteristics and coercive force and a carrier using the same by mixing a Mn compound or the like into hematite and firing in low oxygen or air.

[0007]

Means for solving the problem will be described with reference to FIG. In FIG. 1, the blending step 1 comprises 50 to 65 mol% of a Mn compound, 0 to 2.0 wt% of Ca compound in terms of Ca,
In this step, hematite is blended in an amount of 0 to 3.0 wt% in terms of conversion, and hematite as the balance.

The granulating step 4 is a step of granulating the mixed powder. In the firing step 5, the granulated material is heated to, for example, 1300 ° C.
And firing in low oxygen or air.

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, 50 to 65 mol% of a Mn compound, 0 to 2.0 wt% of a Ca compound in terms of Ca, 0 to 3.0 wt% of a Si compound in terms of Si, and hematite as a balance, The powder mixed and mixed in the granulating step 4 is granulated, and the granulated material is calcined in low oxygen or air at, for example, 1300 ° C. in the calcining step 5 to produce an oxide magnetic material. I have.

In the coating step 7, the oxide magnetic material is coated with a resin to manufacture a carrier. Therefore, a Mn compound, further a Ca compound and S
The i-compound is mixed with 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.

[0012]

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

FIG. 1 is a block diagram showing an embodiment of the present invention.
In FIG. 1, the blending step 1 is performed in the Mn compounds 50 to 6
5 mol%, Ca compound is 0 to 2.0 wt% in terms of Ca
%, The Si compound is 0 to 3.0 wt% in terms of Si, and hematite as the balance.

In the mixing step 2, the mixed powder obtained by mixing the Mn compound, the Ca compound and the Si compound, and the hematite mixed in the mixing step 1 is mixed with -CC- or -C.
This is a step of mixing 0.1 to 4.0 wt% of a liquid substance or a powder substance having = C- in the molecule.

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 heat-treated in low oxygen or air at a temperature of, for example, 1300 ° C. for 2 hours, and a magnetic phase having a spinel structure and a non-magnetic phase are mixed. This is a step of forming a powder.

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 iron oxide and the Mn compound, which are the main components, and the Ca compound and the Si compound are granulated in a predetermined composition, and are fired in the air (or low oxygen) from the beginning.
By performing in an atmosphere, the magnetization under a practical magnetic field can be 35.
An oxide magnetic material that was an emu / g or more oxide magnetic material and did not cause dielectric breakdown even when the electric field characteristic of resistivity was 5000 V / cm could be produced. Further, the coercive force at that time is also 10 Oe or less, and the conventional Mg-based or Ca
A value (10 Oe or less) which was difficult to realize even in the system (about 20 to 50 Oe) was obtained.

FIG. 2 shows an experimental example (part 1) of the present invention. This is because Mn as a main component is 25 to 8 in terms of MnO.
0 mol%, the remaining Fe ₂ O ₃ , and CaCO ₃
0～5.0Wt% with Ca terms, after mixing them 0～10.0Wt% of SiO ₂ in terms of Si as the starting material, polyvinyl alcohol is added to 2.0 wt%, it was mixed with water to powder A slurry having a concentration of 50 wt% was prepared, stirred for 1 hour with an attritor, and then granulated with a spray drier.
Thereafter, the mixture was calcined at about 1300 ° C. for 2 hours in an electric furnace while controlling the oxygen concentration (constant oxygen concentration at 21% O ₂ ) to obtain an oxide magnetic material. FIG. 5A shows a heating pattern. The manufactured oxide magnetic material is embedded in a sample resin holder having a diameter of 6 mm, and is embedded in a VSM (vibrating magnetometer).
The magnetic properties of kOe (maximum magnetization σs) were measured (see FIG. 5C). 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 examples shown in FIGS. 2 and 3 will be described. FIG. 2A shows 1300 ° C. and 1,0% O _2.
This is an experimental example. -Examples 1 to 3 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 50 mol%, but the lower limit of Fe ₂ O ₃ is 3%.
5 mol%. In this case, the minimum value of the magnetization is 43.5 emu / g, the maximum value of the coercive force is 8.5 Oe, and the minimum value of the resistivity characteristic is 5000 V / cm. Magnetization 35 emu / g,
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.

The upper limit of MnO is 65 mol%, and the lower limit of MnO is 50 mol%. At this time,
The minimum value of the magnetization is 43.5 emu / g, the maximum value of the coercive force is 8.5 Oe, and the minimum value of the resistivity characteristic is 5000 V / cm.
5 emu / g, coercive force 10 Oe or less, resistivity characteristic 500
It corresponds to 0 V / cm or more and is judged to have good magnetic properties.

FIG. 2 (b) shows a temperature of 1300 ° C., 21.0 ° C.
This is an experimental example of% O ₂ (in air). This is because 1300 ° C. of 1.0% O ₂ of FIG.
It was in air (21.0% O ₂ ).

Examples 1 to 3 show experimental examples in which the magnetization, coercive force, and resistivity characteristics are all good. Here, 'is the upper limit 50 mol% of Fe ₂ O _3,' is lower 35 mole% of Fe ₂ O _3. In these cases, the minimum value of the magnetization is 38.0 emu, the maximum value of the coercive force is 9.5 Oe, and the minimum value of the resistivity characteristic is 5000 V / cm.
In each case, the magnetization is 35 emu / g, the coercive force is 10 Oe or less, and the resistivity characteristic is 50.
It corresponds to 00 V / cm or more, and is judged to have good magnetic properties.

Is an upper limit of 65 mol% of MnO;
'Is the lower limit of 50 mol% of MnO. this','
, The minimum value of the magnetization is 38.0 emu, the maximum value of the coercive force is 9.5 Oe, and the minimum value of the resistivity characteristic is 5000 V /
cm, 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, all of which are considered to be good magnetic characteristics, and are judged to have good magnetic characteristics.

FIG. 2C shows a graph at 1300 ° C. and 21.0 ° C.
This is an experimental example of% O ₂ (in air). This is because Fe ₂ O ₃ is constant at 42 mol%, MnO is 58 mol%, CaCO ₃ is constant at 0.00 wt% and 0.20 wt% in terms of Ca,
An experimental example when SiO ₂ is changed from 0.00 wt% to 10 wt% in terms of Si will be described.

Examples 1 to 6 show experimental examples in which the magnetization, coercive force and resistivity characteristics are all good. Here, is 41 emu / g of magnetization, and SiO ₂ is converted to Si
The upper limit is 3.00 wt% in conversion. Is magnetization 40.0e
mu / g, and the lower limit of SiO ₂ is 0.00w in terms of Si.
t%.

FIG. 2 (d) shows 1300 ° C., 21.0 ° C.
This is an experimental example of% O ₂ (in air). This is because Fe ₂ O ₃ is constant at 42 mol%, MnO is 58 mol%, SiO ₂ is constant at 0.00 wt% and 0.01 wt% in terms of Si, and C
An experimental example when aCO ₃ is changed from 0.00 wt% to 5 wt% in terms of Ca is shown.

Examples 1 to 6 show experimental examples in which the magnetization, coercive force and resistivity characteristics are all good. Here, the magnetization becomes 40.5 emu / g, and CaCO ₃
Becomes 2.00 wt% in terms of Ca. Is magnetization 4
0.0 emu / g, and the lower limit of CaCO ₃ is 0.00 wt% in terms of Ca.

FIG. 3 (e) shows a temperature of 1300 ° C., 21.0 ° C.
This is an experimental example of% O ₂ (in air). This is because SiO ₂
0.01 wt% in terms of i, CaCO ₃ is 0.1% in terms of Ca.
An experimental example is shown in which Fe ₂ O ₃ and MnO are changed while keeping constant at 20 wt%.

Examples 1 to 3 show experimental examples in which the magnetization, coercive force and resistivity characteristics are all good. Here, the magnetization becomes 49.0 emu / g, and the upper limit of MnO is 65 mol%. 'Becomes 54.5 emu / g of magnetization, and the lower limit is 50 mol%.

According to the experimental examples shown in FIGS. 2A to 3E, 50 to 65 mol% of the Mn compound is 0 to 2.0 wt% in terms of Ca. 3.0 wt% Fe ₂ O ₃ was found to be the balance.

FIG. 4 shows an experimental example (part 3) of the present invention. (A) of FIG. 4 shows that CaCO ₃ is 0.2 w
An experiment example ((c) in FIG. 2) when the constant is set to t% is represented by a line graph. Here, the horizontal axis is SiO ₂
Represents the added amount (wt%) of the sample, and the vertical axis represents the magnetization (emu / g).
Represents Here, the magnetization (emu / g) is 35 emu / g
g or more is good.

FIG. 4 (b) is a line graph showing an experimental example (FIG. 2 (d)) when SiO ₂ is fixed at 0.01 wt% in terms of Si. here,
The horizontal axis represents the amount of CaCO ₃ added (wt%), and the vertical axis represents the magnetization (emu / g). Here, magnetization (emu / g)
Is preferably 35 emu / g or more.

FIG. 5 shows an explanatory diagram of the present invention. FIG. 5A shows a heating temperature characteristic during sintering. In this method, heating is performed at a temperature rising rate of 200 ° C./H during firing, and the temperature is maintained for 2 hours after the firing temperature reaches, for example, 1300 ° C., and then a temperature drop of 200 ° C./H is performed. 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. 5B 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 oxide magnetic material B. D. Is the resistivity characteristic (B.
D. ). FIG. 5C is an explanatory diagram of the magnetization (saturated magnetization) of the present invention. This is an explanatory diagram when measuring the magnetization in FIGS. 2 and 3. The horizontal axis represents the intensity HOe of the applied magnetic field, and the vertical axis represents the magnetization intensity M em at that time.
u. The vibrating magnetometer is, for example, 1 kO
In the state where the magnetic field e is applied, the magnetization intensity Msemu of the powder in which the magnetic phase and the nonmagnetic phase are mixed at that time is measured. Then, the saturation magnetization is determined by the following equation: δs = Ms / (weight of powder) [emu / g] (1) The value obtained by the equation (1) is the magnetization emu / g in FIGS.

[0038]

As described above, according to the present invention,
An Mn compound, and further a Ca compound and a Si compound are mixed into 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. became. Thus, the additive Ca compound and the Si compound are simultaneously added to the iron oxide and Mn compounds, which are the main components, and the calcination is performed in the air (or in low oxygen) from the beginning to obtain a predetermined magnetization,
Coercive force and resistivity characteristics can be obtained.

[Brief description of the drawings]

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

FIG. 2 is an experimental example (part 1) of the present invention.

FIG. 3 is an experimental example (part 2) of the present invention.

FIG. 4 is an experimental example (3) of the present invention.

FIG. 5 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 (4)

[Claims] 1. A method in which 50 to 65 mol% of a Mn compound is mixed with hematite and granulated, and the granulated material is fired to have a magnetization of 35 emu or more, a coercive force of 10 Oe or less, and a resistivity characteristic of 5000 V / cm or more. An oxide magnetic material characterized by the following. 2. The method according to claim 1, wherein in addition to 50 to 65 mol% of the Mn compound, 0 to 2.0 wt% of Ca compound in Ca conversion and 0 to 3.0 wt% of Si compound in Si conversion are mixed with hematite. The oxide magnetic material according to claim 1, wherein: 3. The oxide magnetic material according to claim 1, wherein the firing is performed in low oxygen or in air. 4. A carrier coated with the oxide magnetic material produced according to any one of claims 1 to 3.