JP2002080224A - Black magnetic particle powder for black magnetic toner and black magnetic toner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black magnetic particle powder for a black magnetic toner having black color of depth together with excellent photo-durability and fluidity. SOLUTION: This black magnetic toner comprises black magnetic complexed particle powder having average particle size of 0.06 to 1.0 μm in which the particle surface of magnetite powder is coated by an organosilane compound or polysiloxane derived from an alkoxysilane, and an organic blue pigment adheres to at least a portion of the coating, wherein the amount of the adhered organic blue pigment is 1 to 50 pts.wt. to 100 pts.wt. of the magnetite particle powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a black magnetic particle powder for a black magnetic toner which has a deep black color and is excellent in light resistance and fluidity.

[0002]

2. Description of the Related Art In recent years, a main developing method is a one-component developing method that does not require a carrier, and a black toner is provided with a charge having the opposite sign to that of an electrostatic latent image by friction between a black toner and a carrier. A two-component developing method is known in which a black toner is attached to the surface of an electrostatic latent image by electrostatic attraction and the charge is neutralized to develop the toner. Magnetite is used as a magnetic toner in these resins. Composite particles obtained by mixing and dispersing magnetic particle powders such as particle powders are widely used.

In recent years, there has been a strong demand for improvements in the properties of magnetic toners as the quality and speed of copying machines, such as image density and gradation, have increased.

That is, the magnetic toner is used for a copied line image,
It is required that the solid area image has a high degree of blackness and darkness.

[0005] This fact is described in the 27th issue of "Total Materials for Development and Practical Use of Toner Materials" published by Japan Science Information Co., Ltd.
As described on page 2, "High image density is a characteristic of powder development, but greatly affects image characteristics together with fog density described later."

[0006] Further, there is a strong demand for improving the properties of magnetic toners, especially for improving the fluidity.

This fact is described in Japanese Patent Application Laid-Open No. 53-949.
No. 32, "Such a high-resistance magnetic toner has a drawback that it has poor flowability due to its high resistance and tends to cause uneven development. In other words, a high-resistance magnetic toner for PPC is difficult to transfer. While it can maintain the required charge, it is also slightly charged by friction charging or mechano-electret in the manufacturing process even in processes that do not need to be charged other than the transfer process, such as in the toner bottle or the surface of the magnetic roll. It is liable to cause charge aggregation, which causes a decrease in fluidity. "Another object of the present invention is to provide a high-resistance magnetic toner for PPC having improved fluidity to develop the toner. It is intended to obtain a high-quality indirect copy without unevenness, and therefore with excellent resolution and gradation. "

[0008] The above-mentioned improvement in the fluidity of the magnetic toner is increasingly required with the recent decrease in the particle size of the magnetic toner.

[0009] This fact indicates that, as printers such as ICPs are widely deployed on page 121 of the above-mentioned "Total Materials for Development and Practical Use of Toner Materials", higher image quality is required. High resolution and high definition printers are required.Table 1 shows the relationship of resolution when various toners are used, but a small diameter wet toner can provide high resolution. In order to enhance the resolution, it is necessary to reduce the diameter of the toner .... As a report using the small-diameter toner, it is possible to improve the background fog and further reduce the consumption by using the toner of 8.5 to 11 μm.
In addition, when a 6 to 10 micron polyester-based toner is used, there are proposals for improving image quality, stabilizing chargeability, and improving developer life. However, many problems must be solved when using small diameter toner. There are manufacturability, sharpness of particle size distribution, improvement of fluidity, etc. ".

Further, since the magnetic toner is stored for a long time after being printed on the recording paper, it is required that the magnetic toner has excellent light resistance in order to maintain a clear printed surface.

The characteristics of the magnetic toner are closely related to the characteristics of the magnetic particle powder mixed and dispersed in the magnetic toner. In particular, the magnetic particle powder exposed on the surface of the magnetic toner is developed. It is known to affect properties.

That is, the degree of blackness and darkness of the magnetic toner is as follows:
It greatly depends on the degree of blackness and darkness of the magnetic particle powder which is a black pigment contained in the magnetic toner.

As the black pigment, magnetite particles which are practical in terms of magnetic properties such as saturation magnetization value and coercive force value, price and color tone are widely used. However, since the blackness of the magnetite particle powder is not sufficient for magnetic toner, carbon black fine particle powder may be added in addition to the magnetite particle powder. Since the carbon black fine particle powder also has a function as a resistance regulator, the volume specific resistance value is reduced to less than 1 × 10 ¹³ Ωcm when added and mixed in an unnecessarily large amount for the purpose of increasing blackness, It is known that the toner cannot be used as an insulating or high-resistance magnetic toner.

[0014] When the carbon black fine particles are added and mixed in an unnecessarily large amount, the dispersibility of the magnetite particles in the binder resin is also hindered.

Therefore, there is a demand for magnetic particles having a sufficient blackness comparable to the blackness of carbon black added to the magnetic toner.

On the other hand, since the fluidity of the magnetic toner also depends greatly on the surface state of the magnetic particles exposed on the surface of the magnetic toner, it is strongly required that the magnetic particles themselves have excellent fluidity. I have.

Further, since the light fastness of the magnetic toner also depends on the characteristics of the magnetic particle powder in the magnetic toner, improvement in the light fastness of the magnetic particle powder itself is expected.

Conventionally, various attempts have been made to improve the blackness of magnetite particle powder mixed and dispersed in the black magnetic toner in order to improve the blackness of the black magnetic toner. A method in which an organosilane compound generated from alkoxysilane is coated on the surface, a method of attaching carbon black to the organosilane compound coating (Japanese Patent Application Laid-Open No. H11-305480, etc.), (JP-A-60-26954) and a method of coloring magnetic particle powder with a dye (JP-A-59-57249).

[0019]

The black magnetic particle powder for black magnetic toner, which has a deep black color and is excellent in light resistance and fluidity, is the most demanded at present, but has not been obtained yet. .

That is, it is difficult to say that the above-mentioned magnetic particle powder has a deep black color, as shown in the following comparative examples.

The above-mentioned method aims at obtaining a color toner for a color image having a good hue, and does not disclose obtaining a black toner having a deep black color.

In the above-mentioned method, since the magnetite particles are colored with a dye, it is difficult to say that the light fastness is sufficient as shown in the comparative example described later.

Therefore, an object of the present invention is to provide a black magnetic particle powder for a black magnetic toner which has a deep black color and is excellent in light resistance and fluidity.

[0024]

The above technical problems can be achieved by the present invention as described below.

That is, according to the present invention, an average particle in which the surface of a magnetite particle powder is coated with an organosilane compound or polysiloxane formed from alkoxysilane, and at least a part of the coating is coated with an organic blue pigment. A black magnetic toner comprising black magnetic composite particles having a diameter of 0.06 to 1.0 [mu] m, wherein the amount of the organic blue pigment is 1 to 50 parts by weight based on 100 parts by weight of the magnetite particles. Black magnetic particles for use in the present invention (Invention 1).

Further, in the present invention, the particle surface of the magnetite particle powder of the present invention 1 is made of at least one kind selected in advance from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide. Black magnetic particle powder for black magnetic toner, characterized by being coated with an intermediate coating (the present invention 2).

Further, according to the present invention, the surface of the magnetite particles is coated with an organosilane compound or polysiloxane formed from alkoxysilane, and carbon black is adhered to the coating. An organosilane compound or polysiloxane formed from silane is coated, and the organic magnetic blue pigment is attached to at least a part of the coating. The black magnetic composite particles have an average particle diameter of 0.06 to 1.0 μm, and A black magnetic particle powder for a black magnetic toner, wherein the amount of the organic blue pigment attached is 1 to 50 parts by weight based on 100 parts by weight of the magnetite particle powder (Invention 3).

Also, in the present invention, the particle surface of the magnetite particle powder of the present invention 3 is made of at least one kind selected from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide in advance. Black magnetic particle powder for black magnetic toner, characterized by being coated with an intermediate coating (the present invention 4).

Further, the present invention is a black magnetic toner using the black magnetic particle powder according to any one of the present inventions 1 to 4.

The structure of the present invention will be described in more detail as follows.

First, the black magnetic particles according to the present invention will be described.

In the black magnetic particle powder according to the present invention, the surface of the magnetite particle powder as the core particle powder is coated with an organosilane compound or polysiloxane formed from alkoxysilane, and a part of the coating is coated with an organic compound. It is composed of black composite magnetic particles having an average particle diameter of 0.06 to 1.0 μm to which a blue pigment is attached.

Considering the blackness of the obtained black magnetic particle powder, the surface of the magnetite particle powder is coated with an organosilane compound or polysiloxane formed from alkoxysilane, and carbon black adheres to the coating. Magnetite particles are preferred.

The coating amount of the organosilane compound or polysiloxane in the magnetite particle powder in which carbon black is adhered to the surface of the magnetite particle via an organosilane compound or polysiloxane formed from alkoxysilane is determined by the amount of the organosilane compound-coated magnetite particle powder. Alternatively, the amount of carbon black is 0.02 to 5.0% by weight based on the weight of the polysiloxane-coated magnetite particle powder,
It is 1 to 25 parts by weight with respect to 0 parts by weight.

The adhering carbon black may be either a carbon black layer or a partly adhering carbon black layer. Even if the alkoxysilane or polysiloxane is partially exposed, the organic black pigment may be used. An adhesion process can be performed.

The magnetite particles have a sphericity (average longest diameter / average shortest diameter) such as spherical, granular, hexahedral, octahedral, and polyhedral (hereinafter, referred to as “sphericity”) of 1 or more and less than 2. Any of anisotropic particles and anisotropic particles having an axial ratio (average major axis diameter / average minor axis diameter) (hereinafter, referred to as “axial ratio”) of 2 or more such as needle-like, spindle-like, and rice-grain-like. You may.
Considering the fluidity of the obtained black magnetic particle powder, the particle shape of the magnetite particles is preferably isotropic particles, more preferably spherical. The sphericity of the spherical particles is 1.0 to
1.4, preferably 1.0 to 1.3.

The average particle size of the magnetite particles (average major axis diameter in the case of anisotropic particles) is 0.05.
5 to 0.95 μm, preferably 0.065 to 0.75 μm
m, more preferably 0.065 to 0.45 μm.

When the average particle size exceeds 0.95 μm, the obtained black magnetic particles become coarse particles and the coloring power is reduced. When the particle size is less than 0.055 μm, aggregation tends to occur due to an increase in intermolecular force due to finer particles. Therefore, the surface of the magnetite particle powder is uniformly coated with alkoxysilane or polysiloxane, and the organic blue pigment is used. Uniform adhesion treatment becomes difficult.

When the particle shape of the magnetite particles is anisotropic, the upper limit of the axial ratio is preferably 20 and more preferably 1
8, even more preferably 15. The upper limit of the axis ratio is 2
If it exceeds 0, the entanglement of the particles increases, and it becomes difficult to uniformly coat the surfaces of the magnetite particles with the alkoxysilane or polysiloxane and to uniformly coat the particles with the organic blue pigment.

The geometric standard deviation of the particle diameter (long axis diameter in the case of anisotropic particles) of the magnetite particles is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1. 6 or less. When the geometric standard deviation value exceeds 2.0, uniform dispersion is hindered by the existing coarse particles, so that the surface of the magnetite particle powder is uniformly coated with alkoxysilane or polysiloxane and the organic blue pigment is uniformly dispersed. Makes it difficult to perform uniform adhesion treatment. The lower limit of the geometric standard deviation is 1.01.
Those less than 01 are difficult to obtain industrially.

The BET specific surface area of the magnetite particles is 0.5 m ² / g or more. The BET specific surface area value is 0.
If it is less than 5 m ² / g, the magnetite particles are coarse or particles are sintered between the particles and the particles, and the obtained black magnetic particles are coarse particles and the coloring power is reduced. In consideration of the coloring power of the black magnetic particle powder, the BET specific surface area value is preferably 1.0 m ² / g or more, more preferably 1.5 m ² / g or more. Considering the uniform coating treatment with the alkoxysilane or polysiloxane and the uniform adhesion treatment with the organic blue pigment on the surface of the magnetite particle powder, the upper limit is 95 m.
² / g, preferably 90 m ² / g or less, more preferably 85 m ² / g or less.

The fluidity of the magnetite particles is about 25 to 43. Among magnetite particle powders of various shapes, spherical particle powders have excellent fluidity, but still have a fluidity index of 30 to 43.
It is about. In addition, the fluidity of the magnetite particle powder to which the carbon black is attached has a fluidity index of 44.
About 60.

As for the color tone of the magnetite particles, the lower limit of the L ^* value is 7.0 and the upper limit is 18.0, preferably 16.
The lower limit of the a ^* value exceeds about 0.0, the upper limit is about 7.0, preferably about 6.0, the lower limit of the b ^* value is -1.0, and the upper limit is 6 0.0, preferably about 5.0. Regarding the color tone of the magnetite particle powder to which the carbon black is attached, the lower limit of the L ^* value is 2.7, the upper limit is 14.5, preferably about 14.0, and the lower limit of the a ^* value is 0. And the upper limit is about 7.0, preferably about 6.0, and the lower limit of the b ^* value is -1.0, and the upper limit is about 6.0, preferably about 5.0. L ^* value is 1
If it exceeds 8.0, the lightness becomes high, and black magnetic particles having sufficient blackness cannot be obtained. a
^{* When the} value exceeds 7.0, the reddish color is so strong that black magnetic particle powder having a deep color tone cannot be obtained.

The light resistance of the magnetite particle powder was determined by the evaluation method described below so that the lower limit of ΔE ^* exceeded 5.0,
The upper limit is 12.0, preferably 10.0.

The volume resistivity of the magnetite particles is usually about 1.0 × 10 ^{6 to} 5.0 × 10 ⁷ Ω · cm.

The magnetic properties of the magnetite particles are such that the coercive force value is 0.8 to 31.8 kA / m (10 to 400 Oe).
Degree, preferably 1.6-30.2 kA / m (20-3
80 Oe) and 795.8 kA / m (10 k
Oe) in a magnetic field of 50 to 91 Am ² in a magnetic field
/ Kg (50-91 emu / g), preferably 6
0~90Am be about ^{2 / kg (60~90emu / g)} , residual magnetization value 1~35Am ² / kg (1~35
emu / g), preferably 3 to 30 Am ² / kg
(3 to 30 emu / g).

The particle shape and particle size of the black magnetic particles according to the present invention greatly depend on the particle shape and particle size of magnetite particles as core particles, and have a particle morphology similar to core particles.

That is, the black magnetic particles according to the present invention are:
When isotropic magnetite particles are used as the core particles, the average particle diameter is 0.06 to 1.0 μm, preferably 0.06 to 1.0 μm.
7 to 0.8 μm, more preferably 0.07 to 0.5 μm
Having a sphericity of 1 or more and less than 2, preferably 1-1.
8, when the anisotropic magnetite particles are used as core particles, the average major axis diameter is 0.06 to 1.0 μm, preferably 0.07 to 0.8 μm, more preferably 0.07 to 0.8 μm.
0.5 μm, and the axial ratio is 2 to 20, preferably 2 to
18, more preferably 2 to 15.

The average particle diameter of the black magnetic particle powder is 1.0 μm.
If it exceeds m, the particle size is too large and the coloring power is reduced. When the average particle diameter is less than 0.1 μm, aggregation tends to occur due to an increase in intermolecular force due to finer particles, so that dispersibility in a binder resin during magnetic toner production decreases.

If the upper limit of the axial ratio of the black magnetic particles exceeds 20, the particles in the binder resin during the production of the magnetic toner tend to be more narrowed, and the dispersibility tends to decrease.

The geometric standard deviation of the particle diameter (long axis diameter in the case of anisotropic particles) of the black magnetic particles is preferably 2.0 or less, and the lower limit is 1.01, more preferably 1.
01 to 1.8, still more preferably 1.0 to 1.8.
1 to 1.6. When the geometric standard deviation value exceeds 2.0, the coloring power of the black magnetic particle powder is liable to be reduced by the existing coarse particles. 1.01 geometric standard deviation
Less than is difficult to obtain industrially.

The BET specific surface area of the black magnetic particles is
1.0 to 100 m ² / g, preferably 1.5 to 9
5 m ² / g, more preferably 2.0~90m ² / g. When the BET specific surface area value is less than 1.0 m ² / g, the particles are coarse, or the particles are sintered between the particles, and the coloring power is reduced. BET
When the specific surface area value exceeds 100 m ² / g, aggregation tends to occur due to an increase in intermolecular force due to finer particles, so that dispersibility in a binder resin during magnetic toner production decreases.

The fluidity of the black magnetic particles is preferably in the range of 44 to 90, more preferably 45 to 90.
90, and even more preferably 46 to 90. When the fluidity index is less than 44, it is difficult to say that the fluidity is more excellent, and it is difficult to further improve the fluidity of the obtained magnetic toner. Further, inconveniences such as clogging of the hopper are likely to occur in the manufacturing process, and handling becomes difficult.

The color tone of the black magnetic particle powder is L^*Lower bound of value
Value is 3.0, upper limit is 13.5, preferably 11.0,
More preferably 10.0, a^*The upper limit of the value is 0.
0, preferably -0.1, more preferably -0.2, below
Limit value is -2.0, b^*The lower limit of the value is -3.0, higher
The limit value is 5.5, preferably 5.0. According to the present invention
Of the black magnetic particle powder, carbon black adheres
When magnetite particles are used as core particles, the color tone is L
^*The lower limit of the value is 2.0, and the upper limit is 11.0, preferably
10.0, more preferably 8.5, a^*Upper value limit
A value of 0.0, preferably -0.1, more preferably-
0.2, the lower limit is -2.0, b^*The lower limit of the value is-
2.5, and the upper limit is 5.5, preferably 5.0. L
^*When the value exceeds 13.5, lightness increases and black
It is hard to say that the chromaticity is excellent. a ^*Value exceeds 0.0
Has a deeper color due to strong redness
It is hard to say that it is a black magnetic particle powder.

The light resistance of the black magnetic particle powder is ΔE ^* value of 5.0 or less, preferably 4.0 or less in the evaluation method described later.

The desorption rate of the organic blue pigment in the black magnetic particles is preferably 15% or less, more preferably 12% or less. When the desorption rate of the organic blue pigment exceeds 15%, uniform dispersion may be hindered by the desorbed organic blue pigment, and the hue of the desorbed portion of the magnetite particle powder may be black magnetic composite particles. Since it appears on the surface of the powder particles, it is difficult to obtain a uniform hue.

The volume resistivity of the black magnetic particles is
1.0 × 10 ⁵ Ω · cm or more, and preferably 3.0
× 10 ^{5 to} 1.0 × 10 ⁷ Ω · cm. If the volume resistivity is less than 1.0 × 10 ⁵ Ω · cm, the volume resistivity of the black magnetic toner to be obtained is undesirably reduced.

The magnetic properties of the black magnetic particle powder can be controlled by selecting the particle size and shape of the magnetite particles, and the coercive force value is 0 as in the case of the magnetic particle powder generally used for magnetic toner. 0.8 to 31.8 kA / m
(10-400 Oe), preferably 1.6-30.2 k
A / m (20-380 Oe), 795.8 kA
/ M (10 kOe) in a magnetic field of 50
^{~91Am 2 / kg (50~91emu / g} ), ^{preferably, 60~90Am} 2 / kg ^(60~90emu /
g) and the residual magnetization value is from 1 to 35 Am ² / kg (1
３５35 emu / g), preferably 3 to 30 Am ² / kg
(3 to 30 emu / g).

The black magnetic particle powder according to the present invention may be provided, if necessary, by pre-adhering the particle surface of the magnetite particle powder.
Aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide may be coated with an intermediate coating of at least one selected from the group consisting of:
The desorption of the organic blue pigment from the surface of the magnetite particle powder can be further reduced as compared to the case where the organic blue pigment is not coated with the intermediate coating.

The coating amount of the intermediate coating is calculated by converting the magnetite particles coated with the intermediate coating into Al,
iO ₂ terms or terms of Al quantity and 0.01 to 20 wt% in total of SiO ₂ equivalent amount is preferred.

When the amount is less than 0.01% by weight, the effect of reducing the desorption rate of the organic blue pigment cannot be obtained. 0.01 ~
With the coating amount of 20% by weight, the effect of reducing the desorption rate of the organic blue pigment can be sufficiently obtained.

The black magnetic particle powder according to the present invention coated with the intermediate coating has almost the same particle size and geometric standard deviation as the black magnetic particle powder according to the present invention not coated with the intermediate coating. Value, BET specific surface area value, volume specific resistance value, fluidity, color tone (L ^* value, a ^* value, b ^* value), light fastness ΔE ^* value, and magnetic properties. The desorption rate of the organic blue pigment is improved by coating the intermediate coating, and the desorption rate is preferably 12% or less, more preferably 10% or less.

Further, the black magnetic particle powder according to the present invention comprises:
If necessary, the surface of the magnetite particles may be coated with an intermediate coating and then subjected to carbon black.

The coating according to the present invention comprises an organosilane compound (hereinafter referred to as an "organosilane compound") formed from the alkoxysilane represented by the chemical formula (1), a polysiloxane represented by the chemical formula (2), and a chemical compound represented by the chemical formula (3). Modified polysiloxane, a terminally modified polysiloxane represented by Chemical Formula 4, or a mixture thereof.

[0065]

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As the alkoxysilane, specifically,
Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, etc. Can be

In consideration of the adhesion effect and the desorption rate of the organic blue pigment, an organosilane compound formed from methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, isobutyltrimethoxysilane, phenyltriethoxysilane is preferable. Organosilane compounds generated from triethoxysilane and methyltrimethoxysilane are more preferred.

[0068]

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[0069]

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[0070]

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In consideration of the adhesion effect and the desorption rate of the organic blue pigment, a polysiloxane having a methyl hydrogen siloxane unit, a polyether-modified polysiloxane, and a terminal carboxylic acid-modified polysiloxane having a terminal modified with a carboxylic acid are preferred.

The coating amount of the organosilane compound or polysiloxane is preferably 0.02 to 5.0% by weight in terms of Si with respect to the organosilane compound-coated magnetite particle powder or the polysiloxane-coated magnetite particle powder. , More preferably 0.03 to 4.0% by weight.
And still more preferably 0.05 to 3.0% by weight.

When the amount is less than 0.02% by weight, it is difficult to attach 1 part by weight or more of the organic blue pigment to 100 parts by weight of the magnetite particle powder.

If it exceeds 5.0% by weight, the organic blue pigment is added in an amount of 1 to 100 parts by weight of the magnetite particle powder.
Since 50 parts by weight can be adhered, there is no point in coating more than necessary.

The organic blue pigment in the present invention is a phthalocyanine-based pigment such as metal-free phthalocyanine blue, phthalocyanine blue (copper phthalocyanine), fast sky blue (sulfonated copper phthalocyanine) or alkali blue. When considering the color tone, it is preferable to use phthalocyanine blue.

In particular, when light resistance is taken into consideration, low chlorinated copper phthalocyanine and NC-type (non-crystal)
copper phthalocyanine or NC type low chlorinated copper phthalocyanine is preferred.

The adhesion amount of the organic blue pigment is 1 to 50 parts by weight based on 100 parts by weight of the magnetite particle powder.

If the amount is less than 1 part by weight, it is difficult to obtain black magnetic particles having sufficient light resistance, fluidity and desired color tone because the amount of the organic blue pigment attached is insufficient. .

When the amount exceeds 50 parts by weight, the obtained black magnetic particle powder has sufficient light fastness, fluidity, and desired color tone, but has a large amount of the organic blue pigment adhered thereto. The pigment is easily detached, and as a result, the dispersibility in the binder resin during the production of the magnetic toner may be reduced.

Next, the black magnetic toner according to the present invention will be described.

The black magnetic toner according to the present invention comprises the black magnetic particle powder for a black magnetic toner and a binder resin, and optionally contains a releasing agent, a coloring agent, a charge control agent, and other additives. May be contained.

The black magnetic toner has an average particle diameter of 3 to 15.
μm, preferably 5 to 12 μm.

The ratio of the binder resin to the black magnetic particle powder is 50 to 900 parts by weight, preferably 50 to 400 parts by weight, based on 100 parts by weight of the black magnetic particle powder.

As the binder resin, a vinyl polymer obtained by polymerizing or copolymerizing vinyl monomers such as styrene, alkyl acrylate and alkyl methacrylate can be used. Examples of the styrene monomer include styrene and a substituted product thereof. Examples of the alkyl acrylate monomer include acrylic acid, methyl acrylate, ethyl acrylate, and butyl acrylate.

The above-mentioned copolymer has a styrene component of 50 to 50%.
It is preferred to contain 95% by weight.

As the binder resin, a polyester resin, an epoxy resin, a polyurethane resin, or the like can be used in combination with the vinyl polymer, if necessary.

The fluidity index of the black magnetic toner is 70 to 100, preferably 71 to 100, and more preferably 72 to 100. If it is less than 70, it is difficult to say that the fluidity is more excellent.

The color tone of the black magnetic toner is L^*Lower value
Is 2.0, the upper limit is 13.5, preferably 11.0.
More preferably 10.0, a^*The upper limit of the value is 0.
0, preferably -0.1, more preferably -0.2, below
Limit value is -2.0, b^*The lower limit of the value is -3.0, higher
The limit value is 5.5, preferably 5.0. L^*Value is 1
If it exceeds 3.5, the lightness increases and the blackness is excellent.
It is hard to say that it is. a ^*If the value exceeds 0.0
Is a black magnet with a deep color tone due to its strong redness
It is hard to say toner.

The light fastness of the black magnetic toner is evaluated by a ΔE ^* value of 5.0 or less, preferably 4.
0 or less.

The volume resistivity of the black magnetic toner is as follows.
0 × 10 ¹³ Ω · cm or more, preferably 3.0 × 10 ¹³ Ω · cm or more.
10 ¹³ Ω · cm or more, more preferably 5.0 × 10
¹³ Ω · cm or more. If it is less than 1.0 × 10 ¹³ Ω · cm, the charge amount tends to change depending on the usage environment of the toner, and the characteristics tend to be unstable. The upper limit is 1.0
× 10 ¹⁷ Ω · cm or less.

Magnetic properties of the black magnetic toner according to the present invention
Is usually the magnetic toner used for developing the electrostatic latent image.
Similarly, the coercive force value is 0.8-31.8 kA / m (10-4
00 Oe), preferably 1.6-30.2 kA / m (2
0 to 380 Oe), and 795.8 kA / m (10
kOe) in a magnetic field of 10 to 85 Am
²/ Kg (10-85 emu / g), preferably 20-
80 Am²/ Kg (20-80 emu / g), residual magnetization
Value is 1 to 20 Am²/ Kg (1-20 emu / g), good
Preferably 2-15 Am²/ Kg (2 to 15 emu / g)
And in a magnetic field of 79.6 kA / m (1 kOe)
Magnetization value of 7.5 to 65 Am²/ Kg (7.5-
65 emu / g), preferably 10 to 60 Am²/ Kg
(10 to 60 emu / g) and the residual magnetization value is 0.5 to 15
Am²/ Kg (0.5-15 emu / g), preferably
1.0 to 13 Am²/ Kg (1.0-13 emu / g)
It is.

Next, a method for producing the black magnetic particles according to the present invention will be described.

The magnetite particle powder to which carbon black as the core particle powder in the present invention has adhered is obtained by mixing the magnetite particle powder with alkoxysilane or polysiloxane, and coating the particle surface of the magnetite particle powder with alkoxysilane or polysiloxane. Next, it can be obtained by mixing magnetite particle powder coated with alkoxysilane or polysiloxane and carbon black fine particle powder.

The surface of the magnetite particle powder can be coated with alkoxysilane or polysiloxane by mechanically mixing and stirring the magnetite particle powder and the alkoxysilane solution or polysiloxane, or by mixing the magnetite particle powder with the alkoxysilane or polysiloxane solution. What is necessary is just to mix and stir mechanically while spraying polysiloxane. Almost all of the added alkoxysilane or polysiloxane is coated on the surface of the magnetite particle powder.

[0095] The coated alkoxysilane may be partially coated as an organosilane compound generated from the alkoxysilane, which is generated through a coating process. Even in this case, the subsequent attachment of the organic blue pigment is not affected.

In order to uniformly coat the surface of the magnetite particle powder with the alkoxysilane or polysiloxane, it is preferable to previously disaggregate the magnetite particle powder using a pulverizer.

Equipment for mixing and stirring magnetite particle powder and alkoxysilane or polysiloxane, and mixing and stirring an organic blue pigment and magnetite particle powder coated with alkoxysilane or polysiloxane on the particle surface include powders. A device capable of applying a shearing force to the body layer is preferable, and in particular, a device capable of simultaneously performing shearing, spatula and compression, such as a wheel-type kneader, a ball-type kneader, a blade-type kneader, and a roll-type kneader Can be used. In practicing the present invention, a wheel-type kneader can be used more effectively.

Specific examples of the wheel-type kneader include edge runners (synonyms for “mix miller”, “Simpson mill”, and “sand mill”), multi-mul, stots mill, wet pan mill, conner mill, and ring miller. And the like, preferably an edge runner, a multiple, a Stotts mill, a wet pan mill, and a ring muller, and more preferably an edge runner. Examples of the ball-type kneader include a vibration mill and the like. Specific examples of the blade type kneader include a Henschel mixer, a planetary mixer, and a Nauta mixer. Specific examples of the roll-type kneader include an extruder.

The conditions for mixing and stirring the magnetite particle powder and the alkoxysilane or polysiloxane are such that the alkoxysilane or polysiloxane is coated as uniformly as possible on the particle surface of the magnetite particle powder.
The linear load is 19.6 to 1960 N / cm (2 to 200 kg
/ Cm), preferably 98-1470 N / cm (10-
150 kg / cm), more preferably 147 to 980 N
/ Cm (15-100 kg / cm), processing time is 5-1
The processing conditions may be appropriately adjusted within a range of 20 minutes, preferably 10 to 90 minutes. The stirring speed is 2 to 2000 rpm
m, preferably 5 to 1000 rpm, more preferably 1
The processing conditions may be appropriately adjusted within the range of 0 to 800 rpm.

The mixing and stirring with the magnetite particle powder is performed by adding N
It is preferable to perform the treatment by purging an inert gas such as ₂ .

The addition amount of the alkoxysilane or polysiloxane is preferably 0.15 to 45 parts by weight based on 100 parts by weight of the magnetite particle powder. With an addition amount of 0.15 to 45 parts by weight, 1 to 50 parts by weight of the organic blue pigment can be attached to 100 parts by weight of the magnetite particle powder.

After coating the surface of the magnetite particle powder with alkoxysilane or polysiloxane, an organic blue pigment is added, and the mixture is stirred to adhere the organic blue pigment to the alkoxysilane coating or polysiloxane coating. If necessary, drying or heat treatment may be further performed.

The organic blue pigment is preferably added little by little over time, especially over about 5 to 60 minutes.

The conditions during the mixing and stirring were such that the linear load was 19.6 to 1960 so that the organic blue pigment adhered uniformly.
N / cm (2-200 Kg / cm), preferably 98-
1470 N / cm (10 to 150 kg / cm), more preferably 147 to 980 N / cm (15 to 100 kg / cm)
cm), the treatment time is 5 to 120 minutes, preferably 10 to 9 minutes.
The processing conditions may be appropriately adjusted within a range of 0 minutes. The stirring speed is 2 to 2000 rpm, preferably 5 to 1000 rpm.
The processing conditions may be appropriately adjusted within the range of rpm, more preferably in the range of 10 to 800 rpm.

The addition amount of the organic blue pigment is 1 to 50 parts by weight based on 100 parts by weight of the magnetite particle powder. If the amount of the organic blue pigment is out of the above range, the desired black magnetic particle powder cannot be obtained.

The heating temperature in the drying or heating treatment is usually preferably from 40 to 200 ° C., more preferably 6 to 200 ° C.
The heating time is preferably from 10 minutes to 12 hours, more preferably from 30 minutes to 3 hours.

The alkoxysilane used for coating the obtained black magnetic particle powder is coated with an organosilane compound finally produced from the alkoxysilane through these steps.

If necessary, the magnetite particle powder is selected from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide before mixing and stirring with alkoxysilane or polysiloxane. It may be coated with at least one kind of intermediate coating.

The coating with the intermediate coating is carried out by adding an aluminum compound, a silicon compound or both compounds to an aqueous suspension obtained by dispersing the magnetite particle powder and mixing and stirring, or if necessary, mixing. After stirring p
By adjusting the H value, the particle surface of the magnetite particle powder is coated with an intermediate coating comprising at least one selected from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide. Then, the mixture is filtered, washed with water, dried and pulverized. If necessary, a deaeration / consolidation treatment may be performed.

As the aluminum compound, aluminum salts such as aluminum acetate, aluminum sulfate, aluminum chloride and aluminum nitrate, and alkali aluminates such as sodium aluminate can be used.

As the silicon compound, No. 3 water glass, sodium orthosilicate, sodium metasilicate and the like can be used.

Next, a method for producing the black magnetic toner according to the present invention will be described.

The black magnetic toner according to the present invention can be produced by a known method of mixing, kneading, and pulverizing a predetermined amount of a binder resin and a predetermined amount of black magnetic particle powder.
Specifically, the black magnetic particle powder and the binder resin, if necessary, a mold release agent, a colorant, a charge control agent, after sufficiently mixing a mixture to which other additives are added by a mixer, By dispersing the black magnetic particle powder and the like in the binder resin by a heat kneading machine, and then cooled and solidified to obtain a resin kneaded product, by pulverizing and classifying the resin kneaded product to a desired particle size. can get.

As the mixer, a mixer such as a Henschel mixer or a ball mill can be used.
As the heating kneader, a roll mill, a kneader, a twin-screw extruder, or the like can be used. The pulverization can be performed by a pulverizer such as a cutter mill and a jet mill, and the classification can also be performed by a known air classification as described in Japanese Patent No. 2683142.

As another method for obtaining a black magnetic toner, there is a suspension polymerization method or an emulsion polymerization method. In the suspension polymerization method, the polymerizable monomer and the black magnetic particle powder, if necessary, a colorant, a polymerization initiator, a cross-linking agent, a charge control agent, a mixture added with other additives is dissolved or dispersed. The obtained monomer composition is added to an aqueous phase containing a suspension stabilizer with stirring, granulated, and polymerized to a desired particle size.

In the emulsion polymerization method, the desired particles can be obtained by adding the emulsifier during the polymerization by dispersing the monomer and the black magnetic particle powder in water and, if necessary, a polymerization initiator and the like. Obtained by size.

[0117]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention is as follows.
It is as follows.

The average particle diameter or the average major axis diameter and average minor axis diameter of the particles are all electron micrographs (× 20,000).
Was longitudinally and laterally enlarged by a factor of two, and the major axis diameter and the minor axis diameter of 350 particles shown in the photograph were measured, and the average value was shown.

The axial ratio is represented by the ratio between the average major axis diameter and the average minor axis diameter, and the sphericity is represented by the ratio between the average maximum major axis and the average minimum minor axis.

The geometric standard deviation value of the particles was represented by a value obtained by the following method. That is, a value obtained by measuring the particle diameter (major axis diameter) of the particles shown in the enlarged photograph is statistically calculated from the actual particle diameter (major axis diameter) and the number of the particles calculated from the measured values. According to the method, the horizontal axis represents the particle diameter (major axis diameter) of the particles, and the vertical axis represents the cumulative number of particles (below the integrated screen) belonging to each of the predetermined particle diameter (major axis diameter) sections on a lognormal probability paper. Plot with.

From the graph, it is found that the number of particles is 50.
% And a particle diameter (major axis diameter) corresponding to 84.13%, respectively, and a geometric standard deviation value = 8 under the integrated screen.
4. Particle size at 13% (major axis diameter) / Under integrated screen 5
The value was calculated according to the particle diameter (major axis diameter) (geometric mean diameter) at 0%. The closer the geometric standard deviation value is to 1, the more
It means that the particle size distribution is excellent.

The specific surface area was indicated by a value measured by the BET method.

The amounts of Al and Si present inside the particles and on the surface of the magnetite particles and the amount of Si contained in the organosilane compound or polysiloxane formed from the alkoxysilane were determined by X-ray fluorescence analysis. The measurement was performed according to JIS K0119 “General rules for X-ray fluorescence analysis” using “Apparatus 3063M” (manufactured by Rigaku Corporation).

The amount of each Si contained in each of the organosilane compound or polysiloxane formed from silicon oxide, silicon hydroxide and alkoxysilane covering the surface of the magnetite particle powder is determined by the treatment. The amount of Si was measured at each stage after the process, and the value was obtained by subtracting the amount of Si measured at the stage before the treatment process from the measured value.

The amount of carbon black and organic blue pigment adhering to the black magnetic particles was determined by measuring the carbon amount using a Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 (Horiba, Ltd.). I asked by doing.

The fluidity of the magnetite particle powder, the black magnetic particle powder and the black magnetic toner was measured using a Powder Tester (manufactured by Hosokawa Micron Corporation) using the angle of repose (degree),
Each powder characteristic value such as compression degree (%), spatula angle (degree), and cohesion degree was measured, each index was obtained by replacing each measured value with the same reference value, and the fluidity was calculated by summing each index. It was indicated by an index. The closer the fluidity index is to 100, the better the fluidity is.

The color tone of the magnetite particle powder, the black magnetic particle powder, the organic blue pigment and the black magnetic toner was determined by kneading 0.5 g of a sample and 1.5 ml of castor oil with a Hoover-type muller to form a paste. After adding 4.5 g, the mixture was kneaded and made into a paint to prepare a coated piece (coating thickness: about 30 μm) applied on a cast-coated paper using a 150 μm (6 mil) applicator. The color index L ^* value, a ^* value, and b ^* value were measured according to JIS Z 8729 using "Color Guide 45/0" (manufactured by BYK Japan KK).

Here, the L ^* value represents lightness, and the smaller the L ^* value, the better the blackness. Also, a ^*
The value represents redness, and a smaller a ^* value indicates less redness.

The light fastness of the magnetite particle powder, the black magnetic particle powder, the organic blue pigment and the black magnetic toner was determined by blending 10 g of the sample powder, 16 g of aminoalkyd resin and 6 g of thinner in a 140 ml glass bottle together with 90 g of 3 mm φ glass beads. After adding and then mixing and dispersing with a paint shaker for 45 minutes, 50 g of aminoalkyd resin was added, and the mixture was further dispersed with a paint shaker for 5 minutes.
(× 70 mm × 150 mm) (JIS G-3141) with a thickness of 150 μm and dried to form a coating film. Half of the measurement sample piece is covered with a metal foil, and an eye super UV tester (SUV-W13 ( Using Iwasaki Electric Co., Ltd.), ultraviolet rays were continuously irradiated at an irradiation intensity of 100 mW / cm ² for 6 hours, and then covered with a metal foil to obtain a color tone (L) between the unirradiated part and the irradiated part. ^* Value, a ^* value, and b ^* value) were measured, and indicated by ΔE ^* value calculated according to the following equation 1 based on the measurement value of a portion that was not irradiated with ultraviolet rays by covering with a metal foil.

[0130]

(Equation 1) ΔE^*Value = ((ΔL^*value)²+ (Δa^*value)²
+ (Δb^*value)²)^1/2  ΔL^*Value: L of sample to be compared with or without UV irradiation^*Value of
Difference Δa^*Value: a with or without UV irradiation of the sample to be compared^*Value of
Difference Δb^*Value: b of the sample to be compared with / without UV irradiation^*Value of
difference

The desorption rate (%) of the organic blue pigment adhering to the black magnetic particles was shown by the value obtained by the following method. The closer the desorption rate of the organic blue pigment is to 0%, the smaller the desorption amount of the organic blue pigment from the particle surface of the black magnetic particle powder is.

3 g of black magnetic particle powder and 40 m of ethanol
was placed in a 50 ml sedimentation tube, subjected to ultrasonic dispersion for 20 minutes, and allowed to stand still for 120 minutes to separate the black magnetic particle powder and the separated organic blue pigment by the sedimentation speed. Then
Ethanol (40 ml) was again added to the black magnetic particle powder, ultrasonic dispersion was further performed for 20 minutes, and the mixture was allowed to stand for 120 minutes to separate the separated organic blue pigment from the black magnetic particle powder. This black magnetic particle powder is dried at 80 ° C. for 1 hour,
The amount of the organic blue pigment was measured, and the value determined according to the following equation 2 was defined as the desorption rate (%) of the organic blue pigment.

[0133]

## EQU2 ## Desorption rate (%) of organic blue pigment = ｛(Wa-W)
e) / Wa｝ × 100 Wa: Amount of organic blue pigment attached to black magnetic particle powder We: Amount of organic blue pigment attached to black magnetic particle powder after desorption test

The dispersibility of the black magnetic particles in the binder resin can be determined by photographing a cross section of the obtained black magnetic toner particles using an “optical microscope BH-2” (manufactured by Olympus Optical Industries, Ltd.). It was determined by counting the number of undispersed aggregated particles in the obtained micrograph (× 200), and was evaluated on a scale of 1 to 5. 5 indicates that the dispersion state is the best. 1: 0.25 mm 50 or more per ² 2: 0.25 mm less than 50 10 or more per ² 3: 0.25 mm ² per 5 or more 10 than 4: 1 or more per 0.25 mm ² Less than 5 5: No undispersed material was found

The average particle size of the black magnetic toner is described in “Laser diffraction particle size distribution analyzer model HELOSL”.
A / KA "(manufactured by SYMPATEC).

The volume resistivity of the magnetite particle powder, the black magnetic particle powder and the black magnetic toner was determined by first measuring 0.5 g of the particle powder to be measured, and using a “KBr tablet press”.
1.372 × 10 using (Shimadzu Corporation)
Pressure molding was performed at a pressure of ⁷ Pa (140 kg / cm ² ) to produce a cylindrical sample to be measured.

Next, after the sample to be measured was exposed to an environment of a temperature of 25 ° C. and a relative humidity of 60% for 12 hours or more, the sample to be measured was set between stainless steel electrodes, and “Wheatstone Bridge TYPE2768” (Yokogawa Hokushin Electric Co., Ltd.) (Manufactured by K.K.) and a resistance R (Ω) was measured by applying a voltage of 15V.

Next, the area A (cm ² ) and the thickness t ₀ (cm) of the upper surface of the sample to be measured (cylindrical) were measured, and
And insert the respective measured values into the volume resistivity (Ω ·
cm).

[0139]

## EQU3 ## Volume specific resistance (Ω · cm) = R × (A / t ₀ )

The magnetic properties of the magnetite particle powder, the black magnetic particle powder and the black magnetic toner were measured using a vibration sample magnetometer VSM-3S-15 (manufactured by Toei Kogyo Co., Ltd.) and an external magnetic field of 795.8 kA / m (10 kOe). The magnetic properties of the black magnetic toner are as follows: an external magnetic field of 79.6 kA / m (1 kOe) and 795.8 kA / m.
(10 kOe).

<Production of Black Magnetic Particle Powder> Spherical magnetite particle powder (average particle diameter: 0.27 μm, geometric standard deviation: 1.48, sphericity: 1.2, BET specific surface area: 5.5 m)
² / g, blackness L ^* value 10.9, a ^* value 0.20, b ^*
Value 3.61, light fastness ΔE ^* value 7.1, fluidity index 37,
Volume specific resistance value 4.8 × 10 ⁶ Ω · cm, coercive force value 5.
0 kA / m (63 Oe), 795.8 kA / m (10 k
Oe) saturation magnetization value of 85.0 Am ² / kg (8
5.0emu / g), residual magnetization value 8.0Am ² / kg
(8.0 emu / g)) In order to disintegrate 20 kg, 20 kg of pure water was brought into contact with 150 l of pure water using a stirrer.
The mixture was passed through a “TK pipeline homomixer” (manufactured by Tokushu Kika Kogyo Co., Ltd.) three times to obtain a slurry containing spherical magnetite particles.

Next, the slurry containing the spherical magnetite particles was passed through a horizontal sand grinder “Mighty Mill MHG-1.5L” (manufactured by Inoue Mfg. Co., Ltd.) five times at a shaft rotation speed of 2000 rpm, and
A dispersion slurry containing spherical magnetite particles was obtained.

325 mesh of the obtained dispersion slurry
The sieve residue at (opening 44 μm) was 0%. The dispersion slurry was separated by filtration and washed with water to obtain a cake of spherical magnetite particle powder. After drying the cake of the spherical magnetite particle powder at 120 ° C., the dry powder 11.0 k
g into an edge runner “MPUV-2” (manufactured by Matsumoto Casting Iron Works), and mixed and stirred at 294 N / cm (30 kg / cm) for 30 minutes while blowing 2 l of nitrogen per minute. Was loosened loosely.

Next, methyltriethoxysilane (trade name: TSL8123: manufactured by GE Toshiba Silicone Co., Ltd.)
A methyltriethoxysilane solution obtained by mixing and diluting 110 g with 200 ml of ethanol is added to the spherical magnetite particle powder in which the agglomeration of the particles has been released while operating the edge runner, and 588 N / cm (60 K
(g / cm) under a linear load for 30 minutes to form a coating on the surface of the spherical magnetite particles.
The stirring speed at this time was 22 rpm.

Next, phthalocyanine blue A (particle shape: granular, average major axis diameter 0.06 μm, BET specific surface area value 680 m ² / g, L ^* value 5.2, a ^* value 9.7, b ^* value− 21.8, 825 g of light fastness ΔE ^* value 24.5) were added over 10 minutes while the edge runner was running,
Further, at a linear load of 588 N / cm (60 Kg / cm), 20
After mixing and stirring for minutes, phthalocyanine blue was adhered onto the methyltriethoxysilane coating, and then heat-treated at 105 ° C. for 60 minutes using a drier to obtain black composite magnetite particle powder. The stirring speed at this time was 22 rpm.

The obtained black composite magnetic particles had an average particle size of 0.27 μm. The black composite magnetic particles have a sphericity of 1.2 and a geometric standard deviation of 1.
48, BET specific surface area value of 6.2 m ² / g, fluidity index of 50, blackness L ^* value of 7.5, a ^* value of -0.43,
The b ^* value was -0.28, the light resistance ΔE ^* value was 3.9, the volume resistivity was 8.8 × 10 ⁵ Ω · cm, and the desorption rate of phthalocyanine blue was 5.7%. The magnetic properties are as follows: the coercive force value is 4.9 kA / m (62 Oe), 795.8 kA / m
(10 kOe) at a saturation magnetization of 77.1 Am ² /
kg (77.1 emu / g), the residual magnetization value is 7.2 Am
^{2 /} kg (7.2 emu / g).

As a result of electron micrograph observation, almost no phthalocyanine blue was observed, indicating that almost all of the phthalocyanine blue had adhered to the organosilane compound coating formed from methyltriethoxysilane.

The coating amount of the organosilane compound formed from methyltriethoxysilane was 0.15% by weight in terms of Si, and the adhesion amount of the organic blue pigment was 4.61% by weight in terms of C (100% by weight of spherical magnetite particle powder). Parts by weight).

<Production of Black Magnetic Toner> 450 g of the above-described black composite magnetic particle powder, styrene-butyl acrylate-
550 g of methyl methacrylate copolymer resin (molecular weight 13
000, styrene / butyl acrylate / methyl methacrylate = 82.0 / 16.5 / 1.5), 55 g of polypropylene wax (molecular weight: 3,000) and 15 g of a charge controlling agent were charged into a Henschel mixer, and the temperature in the bath was adjusted to 60 °. Stirring was performed at 150C for 15 minutes. The obtained mixed powder is melt-kneaded at 140 ° C. in a continuous twin-screw kneader (T-1), and the obtained kneaded material is cooled in air, coarsely pulverized, finely pulverized, then classified, and black A magnetic toner was obtained.

The resulting black magnetic toner had an average particle size of 10.0 μm, a dispersibility of 5, a fluidity index of 77, a blackness L ^* value of 8.1, an a ^* value of -0.14, and b. ^* Value is -0.
22, light resistance ΔE ^* value of 3.2, volume resistivity value of 3.2.
8 × 10 ¹⁴ Ω · cm, coercive force value of 4.9 kA / m (6
1Oe), the saturation magnetization at 795.8 kA / m (10 kOe) is 33.4 Am ² / kg (33.4 emu /
g) and a residual magnetization value of 4.2 Am ^{2 /} kg (4.2 emu)
/ G), the saturation magnetization at 79.6 kA / m ( ¹ kOe) is 25.8 Am ^{2 /} kg (25.8 emu / g),
Residual magnetization value is 3.4 Am ^{2 /} kg (3.4 emu / g)
Met.

[0151]

The most important point in the present invention is that the black magnetic particle powder in which an organic blue pigment is adhered to the surface of the magnetite particle powder via an organosilane compound or polysiloxane has a deep black color and has light resistance. And excellent fluidity.

The reason why the black magnetic particle powder having a deep black color is obtained in the present invention is not yet clear, but an organic blue pigment was selected as a pigment for reducing the redness of the magnetite particle powder. The red color of the black composite magnetic particle powder is exhibited by selecting alkoxysilane or polysiloxane as a sizing agent by which the organic blue pigment can be firmly fixed to the magnetite particle powder.
^* It is estimated that the value was reduced to 0 or less.

The reason why the magnetic particle powder according to the present invention is excellent in light resistance is that magnetite particle powder, which is originally poor in light resistance, is coated with an organosilane compound or polysiloxane having excellent light resistance, It is believed that the adhesion of the excellent organic blue pigment improved the light resistance of the black magnetic particle powder.

Regarding the reason that the black magnetic particle powder has excellent fluidity, the present inventor has proposed that the organic blue pigment is uniformly and densely adhered to the surface of the magnetite particle powder. This is considered to be due to the formation of a large number of fine irregularities.

The black magnetic toner according to the present invention obtained by using the above-described black magnetic particle powder to which the organic blue pigment is adhered has a light resistance while maintaining a high resistance of 1 × 10 ¹³ Ω · cm or more. This is the fact that it has a deep black color with excellent properties and fluidity.

Regarding the reason why the fluidity of the black magnetic toner is excellent, the present inventor has proposed that the black magnetic particles having the organic blue pigment adhered to the surface of the magnetite particles are
This is considered to be due to the formation of a large number of fine irregularities exposed on the surface of the black magnetic toner.

Regarding the reason why the black magnetic toner exhibits a deep black color, the present inventors have found that the L ^* value is sufficiently low and the a ^*
This is considered to be due to the fact that black magnetic particle powder having a deep black color having a value of 0 or less was incorporated into the black magnetic toner.

[0158]

Next, examples and comparative examples will be described.

Magnetite particles 1 to 4: Magnetite particles having the properties shown in Table 1 were prepared as magnetite particles.

[0160]

[Table 1]

Magnetite 5 A slurry containing octahedral magnetite particle powder was obtained in the same manner as in the embodiment of the present invention using 20 kg of octahedral magnetite particle powder in which agglomeration of magnetite 1 was disentangled and 150 l of water. Was. The pH value of the redispersed slurry containing the obtained octahedral magnetite particles was adjusted to 10.5 using an aqueous sodium hydroxide solution, and then water was added to the slurry to adjust the slurry concentration to 98 g / l. . 150 l of this slurry was heated to 60 ° C., and 1.0 mol / l of NaAlO ₂
5444 ml of a solution (corresponding to 1.0% by weight in terms of Al with respect to the octahedral magnetite particles) was added, and 30
After holding for minutes, the pH was adjusted to 7.5 with acetic acid. Next, 139 g of No. 3 water glass was added to the slurry.
(Corresponding to 0.2% by weight in terms of SiO _{2 with} respect to the octahedral magnetite particles), and the mixture was aged for 30 minutes. Then, the pH was adjusted to 7.5 using acetic acid. After keeping in this state for 30 minutes, filtration, washing with water, drying, and pulverization were performed to obtain octahedral magnetite particle powder whose particle surface was coated with aluminum hydroxide and silicon oxide.

Table 2 shows the production conditions, and Table 3 shows the properties of the obtained surface-treated magnetite particles.

Magnetites 6 and 7: The surface of the particles was coated in the same manner as the core particles 4 except that the magnetite particles 2 and 3 were used and the type and amount of the surface coating were variously changed. The coated magnetite particle powder was obtained.

The production conditions at this time are shown in Table 2, and various properties of the obtained surface-treated magnetite particle powder are shown in Table 3. In addition, A of the kind of the coating material in the surface treatment step is a hydroxide of aluminum, and S represents an oxide of silicon.

[0165]

[Table 2]

[0166]

[Table 3]

Organic blue pigments A to C: Phthalocyanine blue having various properties shown in Table 4 were prepared as organic blue pigments.

[0168]

[Table 4]

Examples 1 to 7 and Comparative Examples 1 to 5: Types and amounts of additives in the coating step with alkoxysilane and polysiloxane, linear load and time of edge runner treatment, organic blue in the step of adhering organic blue pigment Black composite magnetic particle powder was obtained in the same manner as in the embodiment of the invention except that the kind and amount of the pigment, the line load and the time of the edge runner treatment were variously changed.

Table 5 shows the production conditions at this time, and Table 6 shows various properties of the obtained black composite magnetic particle powder.

Comparative Example 6 (Example 1 of JP-A-59-57249) 100 parts by weight of magnetite particles 1 were mixed with 5 parts by weight of oil black as a blue dye and methanol 1
After being immersed in a solution dissolved in 00 parts by weight, methanol was distilled off.

Table 6 shows the properties of the obtained particles.

[0173]

[Table 5]

[0174]

[Table 6]

Examples 8 to 14 and Comparative Examples 7 to 16: Magnetic toners were obtained in the same manner as in the embodiment of the present invention, except that the types of the black magnetic particles were variously changed.

Table 7 shows the production conditions at this time, and Table 8 shows various characteristics of the obtained magnetic toner.

[0177]

[Table 7]

[0178]

[Table 8]

[0179]

[Table 9]

[0180]

The black magnetic particle powder according to the present invention has a deep black color and is excellent in fluidity and light resistance, and is therefore suitable as a black magnetic particle powder for magnetic toner.

The black magnetic toner according to the present invention has a deep blackness, and is excellent in fluidity and light resistance.
It is suitable as a black magnetic toner.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroko Morii 1-4, Meiji Shinkai, Otake City, Hiroshima Prefecture F-term in Otake Creative Center, Toda Kogyo Co., Ltd. 2H005 AA02 AA03 CA12 CA21 CA26 CB07 CB08 CB18 DA04 DA05 DA10 EA05 EA07 4G002 AA04 AB05 AE01 AE02

Claims (5)

[Claims] An average particle diameter of 0.06, wherein an organosilane compound or polysiloxane formed from alkoxysilane is coated on the surface of the magnetite particle powder, and an organic blue pigment is attached to at least a part of the coating. ~
A black magnetic particle powder for black magnetic toner, comprising 1.0 μm of black magnetic composite particle powder, wherein the amount of the organic blue pigment is 1 to 50 parts by weight based on 100 parts by weight of the magnetite particle powder. . 2. The intermediate coating according to claim 1, wherein the surface of the magnetite particles is at least one selected from the group consisting of aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide. Black magnetic particle powder for black magnetic toner, which is coated with a black magnetic particle. 3. The surface of the magnetite particle powder is coated with an organosilane compound or polysiloxane formed from alkoxysilane, and the coating is coated with carbon black, and further formed on the carbon black from alkoxysilane. An organosilane compound or polysiloxane is coated, and an organic blue pigment is attached to at least a part of the coating.
Black magnetic particle powder for black magnetic toner, comprising black magnetic composite particle powder having a thickness of 1 μm, wherein the amount of the organic blue pigment to be attached is 1 to 50 parts by weight based on 100 parts by weight of the magnetite particle powder. 4. The intermediate coating according to claim 3, wherein the surface of the magnetite particle powder is at least one selected from the group consisting of aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide. Black magnetic particle powder for black magnetic toner, which is coated with a black magnetic particle. 5. A black magnetic toner using the black magnetic particle powder according to any one of claims 1 to 4.