JPS58145622A - Magnetic carrier particle - Google Patents

Abstract

PURPOSE:Magnetic carrier particles having a wide range of change in resistance value, obtained by constituting a ferrite having a composition shown by a specific formula calculated as a bivalent or trivalent metal oxide. CONSTITUTION:Magnetic carrier particles comprising a ferrite having a composition shown by the formulaIcalculated as a bivalent or trivalent metal oxide. In the formula, M is Mn or Zn or a combination of Mn with one or more of Zn, Cu, Mg and Co. When M contains Mn and one or more other elements, a molar ratio of Mn to M is >=0.05, and when M contains Mg, a molar ratio of Mg to M is <0.05; x is >53mol%. MO in the formulaIis preferably a substance shown by the formula II, X is Zn or a combination of Zn with one or more of Cu, Mg and Co in the formula II; y is >=0.05 and <1. The ferrite particles have a spinel structure, <= about 1,000mu average particle diameter, and about 10<4>-10<14>OMEGA at 100V impressed voltage.

Description

[Detailed description of the invention] ■ Background of the invention Technical field The present invention relates to magnetic carrier particles.

More specifically, it relates specifically to magnetic carrier particles for use in magnetic brush development.

Prior art and its problems In magnetic brush development, it has been proposed to use so-called soft ferrite as carrier particles (
U.S. Patent No. 3839029, U.S. Patent No. 3914181, U.S. Patent No. 39296
No. 57, etc.).

Carrier particles made of such ferrite exhibit magnetic properties equivalent to conventional iron powder carriers, and unlike iron powder carriers, there is no need to provide a layer such as resin on the surface, so they are durable. It is extremely expensive.

In this case, the composition of ferrite actually used as carrier particles is (MO)+oo-□(Fe2O2
)

By the way, according to the research results of the present inventors, even if the ferrite particles have the same composition, if the surrounding atmosphere during firing is controlled,
It has been found that the resistance of the particles changes. and,
By changing the resistance of the carrier particles, images with divine gradation can be obtained, and various image qualities can be selected.

Furthermore, by changing the resistance, it is possible to obtain optimum characteristics for various types of throwaway devices.

For this reason, it can be said that the larger the change in resistance value 11'' caused by changing the firing atmosphere, the more preferable the ferrite particles are.

However, as mentioned above, Fe203it 53 mol%
-1 itself has a high resistance value for those with a composition of 8 degrees or higher,
The resulting image density is low. Furthermore, even if the firing atmosphere is changed, the change in resistance value is small, the rate of change in gradation is small, and the image quality cannot be arbitrarily selected.

■Purpose of the invention The present invention was made in consideration of the above-mentioned circumstances, and
The main purpose is to provide a ferrite carrier particle composition with a much wider range of resistance change than conventional methods.

The inventors of the present invention have repeatedly conducted various studies for this purpose, and as a result have completed the present invention.

That is, the present invention provides divalent metal oxides or trivalent gold bm
The magnetic carrier particles are characterized in that they are made of ferrite having a composition expressed by the above formula IJ in terms of oxide.

Formula (l J (MO)+oo −z (Fe20s)
x (In the above formula, M represents Mn, Zn, or a combination of Mn and one or more of Zn, Ou, Mg, and Co. However, if M is an element other than Mn, When containing one or more of the following, the atomic ratio Ii of Mrl in M
0.05 or more.

In addition, when M contains MH, the atomic ratio of Mg in M is 005
less than

Furthermore, X is more than 53 mol% canine. )111 Specific Configuration of the Invention The specific configuration of the present invention will now be described in detail.

In the above formula, M consists of only Mn 4 or Zn, or Mn and Zn, Ou, Mg and c.

It is any combination of 2 to 5 types of elements, including one or more of the following.

On the other hand, Fe1kX converted to Fe203 is 53 mol1]
It's big. When X is 53 mol % or more, the range of change in resistance value becomes small.

When %X becomes 54 mol% or more, the range of resistance value change becomes extremely large.

On the other hand, there is no particular limit on the upper limit of X, and it is 10
It only needs to be less than 0 mol%. In terms of saturation magnetization, it is preferable that X is 99 mol%, more preferably 90 mol% or more. At this time, the saturation magnetization is extremely large, and carriers may adhere to the photoreceptor.
This is because carriers are almost never scattered from the magnetic brush.

On the other hand, M is the same as above, and even if M consists only of Mn(5) or Zn, Mn and other Z
It may be made of one or more of n, Cu, Mg and Co. However, when M contains one or more other elements in addition to Mn, the atomic ratio of Mn in M is 0.
05 or higher.

This is because when the atomic ratio of Mn is less than 0.05, the saturation magnetization decreases and carrier adhesion and carrier removal as described above increase.

In addition, when Mg is included in M, the atomic ratio of Mg is 0.
It is less than 05.

Among the compositions represented by the above formula (IJ),
It is preferable that MO in formula (i) is represented by the above formula (II).

Formula (II') (MnO)y (XO)+-y In the above formula (II), X is Zn or Zn and Cu
, Mg and co. yijO, 05 or more and less than 1.

(6) of the composition represented by the above formula [a] In this case, y is 005 to 0.99. Especially when it comes to 01 to 07, more favorable results are obtained.

Furthermore, the atomic ratio of Zn in X is 1 or 0.3
It is preferable that the value is less than 1.

At this time, the saturation magnetization becomes extremely high.

In addition, X is Zn and 2aI of other Ou, Mg, Co
Alternatively, when a combination of three types is used, the composition ratio of Cu + Mg to Co can be set arbitrarily.

Such ferrite particles have a spinel structure.

Ferrite particles with such a composition generally contain:
It is good if it is within 5 mol% of the total.

Such ferrite particles are usually It has an average particle size of 1000 μm or more.

Generally, a coating layer is not formed on the surface of the particles, and they are used as magnetic carrier particles as they are.

The resistance of the ferrite particles constituting the magnetic carrier particles of the present invention as described above is within the range of 10 4 to 10 14 Ω, particularly 10 5 to 10 12 Ω, when 100 V is applied, when the following measurements are performed.

[2] Within such a resistance value range, the resistance value of the ferrite particles of the present invention changes continuously by changing the firing conditions described below, and the maximum change ratio reaches 105 to 101O. , an electrostatic image of any image quality can be appropriately selected.

The resistance measurement of ferrite particles is performed as follows, imitating the magnetic brush development method.

That is, at an electrode gap of 8, the N pole and S1i! l
Face the i. In this case, the surface magnetic flux density of the magnetic pole is 1
50' Onauss, opposing magnetic pole area is 10X3011
11111. Between the magnetic poles, interelectrode gap 811ff
At l+, nonmagnetic parallel flat electrodes are placed, a test sample 200rn9 is placed between the electrodes, and the sample is held between the electrodes by magnetic force. In this way, resistance can be measured using an insulation resistance meter or an ammeter.

Note that when the resistance measured in this manner exceeds 1014Ω, the image density decreases.

On the other hand, if it is less than 104 Ω, more carriers will adhere to the photoreceptor, and there will also be a tendency for resolution, single gradation, etc. to be low, and image quality to be high contrast.

Furthermore, the saturation magnetization "i" of the ferrite particles in the present invention
n is preferably 35 emu/Si' or more and Ruco. At this time, the so-called carrier attraction in which the carrier adheres to the photoreceptor is eliminated, and the scattering of the carrier during repeated development is eliminated. In this case, when "." is 40 emu/9 or more, a more preferable result is obtained.

Magnetic carrier particles made of such ferrite particles are generally described in U.S. Pat. No. 3,839,029 and U.S. Pat.
No. 3,926,657 (9), etc.

That is, first, a corresponding metal oxide is prepared.

Next, solvent 7, usually water, is added, for example i: yl<' -
The slurry is made into a slurry using Lumil, etc., and a dispersant, a binder, etc. are added as necessary.

Then, it is granulated and dried using a spray dryer.

Thereafter, firing is performed in a predetermined firing atmosphere and furnace U density profile at 9°. Firing follows a conventional method.

In this case, if the molecular oxygen partial pressure during firing is reduced, the resistance value is reduced. When the oxygen partial pressure of the firing atmosphere is continuously changed from air to arsenic atmosphere, the resistance value of the particles changes continuously.

! After completion of 1ffi, the particles are crushed or dispersed and then classified to a desired particle size to produce the magnetic carrier particles of the present invention.

(10) 1v Specific effects of the invention The magnetic carrier particles of the invention are used in combination with a toner on the image side. In this case, there are no restrictions on the type of toner used and the toner concentration.

Further, in obtaining an electrostatic copy image, there is no particular restriction on the magnetic brush development method, photoreceptor, etc. used, and a quiet M''0 copy image can be obtained according to the known magnetic brush development method.

The magnetic carrier particles of the present invention have a wide resistance (i1p change ratio) ranging from 105 to 1010 by producing the magnetic carrier particles by changing the firing atmosphere.

Therefore, carrier particles that give an appropriate image can be easily obtained depending on the type of copying apparatus. In addition, the image quality of the child can be selected.

Furthermore, since there is no need to form a film on the surface, the durability is good.

In addition, the saturation magnetization is 35 emu/1 or more, and so-called carrier attraction and carrier scattering, in which carriers adhere to the photoreceptor, are less likely to occur.

V. Specific Examples of the Invention The present invention will now be described in more detail with reference to specific examples.

Actual rolling example 1 In terms of molar ratio in terms of divalent metal oxide and Fe203, the composition of 6 yuzu shown in Table 1 (sample shop 1 to 6
) The corresponding metal oxides were prepared.

Next, 1 part of water was added per 1 part of this blended composition, and mixed in a mail mill for 5 hours to form a slurry.
Dispersants and binders! Four doses were added.

Next, the mixture was granulated and dried using a spray dryer at a temperature of 15()''C or higher.

Each granule was heated in a rotary kiln at a maximum temperature of 1350 ml in an air atmosphere and a nitrogen atmosphere, respectively.
Calcined at ℃.

This bale was crushed and classified into 811 particles with an average particle size of only 45 μm.
Two types of ferrite particles were obtained.

When Xi group analysis and quantitative chemical analysis were performed on each of the obtained heptagonalite particles, it was confirmed that each particle had a spinel structure and a metal composition corresponding to the above-mentioned blending ratio.

Next, the saturation magnetization '%' of each of the obtained heptagonal light particles
(emu/t) and resistance (Ω) when 100V was applied were measured.

In this case, the saturation magnetization "□" was measured with a vibrating sample type magnetometer.

In addition, the resistance was determined by measuring 1 of the 200 μ sample as described above.
The resistance when 00V was applied was measured using an insulation resistance meter.

Was it measured for each composition? Table 1 below shows the resistance RA in salt 1 air firing in clay firing, the resistance RN in chamber firing, and the resistance change ratio RA/RN.

Furthermore, using each of the ferrite particles as described above as magnetic carrier particles, at a toner concentration of 11.5% by weight,
Commercially available two-component toner (-P average particle size 11.5 large, 1.5μ
m) to prepare a developer.

(13) Using each developer, magnetic brush development was performed using a commercially available electrostatic copying machine.

In this case, the surface magnetic flux density of the magnetic roller for the magnetic brush is 1000 Gauss, and the rotation speed is 90 rpm. Also, the magnetic roller-photoreceptor gap is 4.
0±0.3M.

Furthermore, a selenium photoreceptor was used as the photoreceptor, and the highest surface potential was 5oov.

Using Eastman Kodak gray steel,
Using the above electrostatic copying machine, a toner image is obtained on plain paper,
The image density at an original density (OD) of 1.0 was determined, and the N of the particles fired in a nitrogen atmosphere and the ID of the particles fired in air were determined for each composition.
) The difference from A was calculated.

The results are also listed in Table 1.

In addition, most of the magnetic carrier particles had almost no carrier adhesion to the photoreceptor, and almost no carrier scattering, but samples A5 and 6 with Fe20353 mol% or more (14) were fired in air. σ is 40 emu/In? As a result, carrier adhesion and carrier scattering were observed.

(15) From the results shown in Table 1, it can be seen that (the magnetic carrier particles of the present invention in which the Fe203 content It can be seen that the degree is extremely large.

In the above, when the firing atmosphere was a mixed gas of air and nitrogen and the mixing ratio was variously changed, it was confirmed that the resistance and image density changed continuously between the above values.

Example 2 Magnetic carrier particles were prepared according to Example 1 with the composition shown in Table 2, and the above RA was obtained.

RN, RA-RN and (more) N-(ID
) A was measured.

The results are shown in Table 2.

From the results shown in Table 2, the effects of the present invention are clear.

In samples A9 to A16, 40 emu/11" or higher was obtained, indicating that there was almost no carrier pull or carrier dropout, or in samples A7 and A8, □ was 20
It was less than e+nu/li', and carrier pull and carrier scattering were large.

Applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Agent Patent Attorney Tadashi Ishii - (19) (18) Teito Mitsuru j]'E (spontaneous) 1. Indication of the case 1982 Patent Application No. 20964 2. Invention Name of Magnetic Carrier Particle 3, Relationship with the case of the person making the amendment Patent applicant's office
Nihonbashi-chome 13-1, Chuo-ku, Tokyo Name
(306) TDC Co., Ltd. Representative Hiroshi Otoshi 4, Agent 171 Address 5-17-11 Nishiikebukuro, Toshima-ku, Tokyo
Goyabe Building 1st Floor Telephone: 988-16806, The statement in the column "3. Detailed explanation of the invention" in the statement of contents of the amendment is amended as shown in F.

l) In the 19th line of page 8, "Parallel plate electrode J" is corrected to "Parallel plate electrode J."

2) In the 16th line of the 12th page, the phrase ``No air atmosphere'' is corrected to ``Nitrogen atmosphere containing oxygen.''

3) On page 13, line 13, replace “in the air” with “
Corrected as j in a nitrogen atmosphere containing oxygen.

4) On page 14, line 14, it says “1 in the air,”
"In a nitrogen atmosphere containing oxygen."

5) In the 6th line of page 17, 1 air and 1 are corrected to ``oxygen and''.

6) In Table 2 on page 18, as the sample amount and the R/RN value of 14 (wood invention), I'lOj is written as 07j.
and correct it.

7) R of sample amount 15 (comparison) in Table 2 on page 18
The value of /RN is 1m1oj.
Correct as n.

8) Samples 1i and 16 (wood invention) in Table 2 on page 18
As the R/RN value of i'lo j, i
Correct as to”j.

-12:

Claims (1)

[Claims] Divalent metal fluoride or trivalent metal oxide? ! Magneto carrier particles characterized by being composed of ferrite having a composition expressed by the following formula (I3) in terms of +. Formula CI) (MO)100-X(Fe20s)x (In the above formula, Mr , Mn, Zn1 or Mn and Zn
, Cu, Mg and co. However, M is 1 of other elements in addition to Mn.
When more than one species is included, the atomic ratio of ~1n in M is 0.05 or more. In addition, when M or Mg is included, the atomic ratio of Mg in M is 0.
It is less than 05. ) Furthermore, x is greater than 53 mol%.