JP2004161608A - Iron-based black particle powder and black toner containing iron-based black particle powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide iron-based black particle powder having excellent blackness and low magnetization value as much as possible, used as a coloring material for a black pigment, coating material or resin composition and exhibiting excellent blackness particularly in the case of being used for non-magnetic black toner and to provide the black toner having low magnetization. <P>SOLUTION: The iron-based black particle powder is composed of an FeTiO<SB>3</SB>-Fe<SB>2</SB>O<SB>3</SB>solid solution or a mixed composition of an FeTiO<SB>3</SB>-Fe<SB>2</SB>O<SB>3</SB>solid solution and an iron-based oxide having spinel type structure, contains 10.0-40.0 atom% Ti per total Fe expressed in terms of Ti and has 5-40 Am<SP>2</SP>/kg saturation magnetization value, a blackness L<SP>*</SP>value of 6-13 and 0.01-0.5 μm average particle diameter. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention provides an iron-based black particle powder having an excellent blackness and a magnetization value as low as possible.

  The non-magnetic black particle powder according to the present invention can be used as a pigment and a paint exhibiting black, a coloring material for a resin composition, and the like. An excellent black toner having a low magnetization value can be provided.

  BACKGROUND ART Black pigments such as magnetite particle powder, ilmenite particle powder, and carbon black have been widely used as coloring agents for paints, printing inks, cosmetics, rubber / resin compositions, and the like since ancient times.

  In particular, composite particles obtained by mixing and dispersing black magnetic iron oxide particles such as magnetite particles in a resin are widely used in magnetic toners used as electrophotographic developers.

  In recent years, as the speed and image quality of laser beam printers and digital copiers have increased, there has been a strong demand for improved characteristics of the black toner as a developer. It is strongly required to have.

  Further, in recent years, full-color printing has been promoted, and non-magnetic toner has been used for corresponding printers and copiers.

  Therefore, there is a demand for a black non-magnetic toner which is non-magnetic or has a magnetization value as small as possible and is compatible with the current system.

  As described above, there is a strong demand for improvement of various characteristics of the black non-magnetic toner. Black non-magnetic toner, in particular, the black pigment contained in the toner, is known to greatly affect the development characteristics, various characteristics of the black non-magnetic toner and the black non-magnetic toner are mixed and dispersed There is a close relationship with the characteristics of the black pigment, and there is a strong demand for further improvement of the characteristics of the black pigment used in the black non-magnetic toner.

  That is, in order to obtain a black non-magnetic toner having excellent blackness, it is required that the black particle powder has a sufficient blackness and more excellent dispersibility. Furthermore, in order to be compatible with the current system using a non-magnetic toner, a non-magnetic particle powder having a magnetization value as low as possible is required as a black particle powder.

On the other hand, although carbon black is non-magnetic, it is difficult to disperse in a vehicle or a resin composition because the particle size is a fine particle powder having an average particle diameter of about 0.005 to 0.05 μm. It is known that since the powder has a high density of about 0.1 g / cm ³ , it is difficult to handle and the workability is poor.

  Therefore, there is a demand for a black particle powder having excellent blackness and a magnetization value as low as possible.

Ilmenite particle powder obtained by hydrothermal treatment as a black iron-based particle powder (Patent Document 1), a black pigment composed of a mixed composition of Fe ₂ TiO ₅ and Fe ₂ O ₃ —FeTiO ₃ solid solution (Patent Reference 2), black magnetic iron oxide particles having a magnetization value σ ₁₀₀₀ of 20 to 50 Am ² / kg and containing 0.5 to 10.0 atomic% of titanium with respect to the total Fe (Patent Document 3), titanium Is known (Patent Document 4).

JP-A 1-298028 JP-A-3-2276 JP-A-8-34617 JP-A-2002-196528

  Iron-based black particle powders having excellent blackness and as low a magnetization value as possible have been most demanded at present, but have not been obtained yet.

That is, Patent Document 1 mentioned above describes that ilmenite particle powder is obtained by hydrothermal treatment using Ti ³⁺ , but it is manufactured by hydrothermal treatment and is hardly industrial.

The non-magnetic particle powder described in Patent Document 2 described above contains Fe ₂ TiO ₅ and thus has a low magnetization value. However, as shown in Comparative Examples below, the non-magnetic particle powder has low coloring power and satisfies blackness. It is hard to say.

The black magnetic iron oxide particles described in Patent Document 3 described above have a Ti content of 0.5 to 10 atomic% and a magnetization value σ ₁₀₀₀ in a magnetic field of 79.58 kA / m (1 kOe) of ²⁰ to 50 Am ^2. / Kg (20 to 50 emu / g), which is high, and cannot be said to be sufficiently compatible with non-magnetic systems.

Patent Document 4 described above describes a black toner containing a metal oxide having a magnetization of 40 Am ² / kg (40 emu / g) or less. In Examples, a blue pigment is used together with Ti-containing magnetite particle powder. Therefore, it is difficult to obtain a satisfactory hue by using the Ti-containing magnetite particles alone.

  Therefore, an object of the present invention is to obtain iron-based black particles having excellent blackness and a low magnetization value.

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

That is, the present invention comprises a FeTiO ₃ —Fe ₂ O ₃ solid solution or a mixed composition of a FeTiO ₃ —Fe ₂ O ₃ solid solution and an iron-based oxide having a spinel structure, and the Ti content is Ti It is 10.0 to 40.0 atomic% in conversion, the saturation magnetization value is 5 to 40 Am ² / kg, the blackness L ^* value is 6 to 13, and the average particle diameter is 0.01 to 0.50 μm. It is an iron-based black particle powder characterized by the following (Invention 1).

Further, the present invention is, ₍₁₎ FeTiO 3 _-Fe 2 _{O 3} solid solution or FeTiO ₃ -Fe mixed composition of iron-based oxide having ₂ O ₃ solid solution and spinel structure 80 to 99.9 weight and (2 A) a blue pigment of 0.1 to 20% by weight, a Ti content of 10.0 to 40.0 atom% in terms of Ti with respect to all Fe, a saturation magnetization of 5 to 40 Am ² / kg, It is an iron-based black particle powder having a degree L ^* value of 6 to 13 and an average particle size of 0.01 to 0.50 μm (Invention 2).

  Further, the present invention provides a black toner using the iron-based black particle powder of the present invention 1 or 2. (Invention 3)

  The iron-based black particle powder according to the present invention is excellent in blackness and has as low a magnetization value as possible, and thus is suitable as a pigment and a paint exhibiting black, a coloring material for a resin composition, a filler, and the like.

  The black non-magnetic toner produced by using the iron-based black particle powder according to the present invention has a high degree of blackness and a low magnetization value, and thus is suitable as a non-magnetic toner.

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

  First, the iron-based black particle powder according to the present invention will be described.

Black iron-based particles according to the present invention _consists of a mixed composition of iron-based oxide having a FeTiO _{3 -Fe} 2 _O 3 solid solution or FeTiO ₃ -Fe ₂ O ₃ solid solution and spinel structure. The iron-based oxide having a spinel structure is, for example, a Fe ₃ O ₄ -γ-Fe ₂ O ₃ solid solution. When Fe ₂ O _{3 is used} alone (does not contain FeTiO ₃ ), the color is red and the blackness desired by the present invention cannot be obtained. When FeTiO _{3 is used} alone (does not contain Fe ₂ O ₃ ), heat treatment at a higher temperature is required, and the obtained particles have a large particle diameter, and thus a desired coloring power cannot be obtained.

The content of the Fe ₃ O ₄ -γ-Fe ₂ O ₃ solid solution in the iron-based black particle powder according to the present invention is determined by the (104) plane of FeTiO ₃ -Fe ₂ O ₃ in the peak intensity of the X-ray diffraction described later. The peak intensity of the (220) plane of Fe ₃ O ₄ -γ-Fe ₂ O ₃ is preferably 1: 0.05 to 1: 0.5 with respect to the peak intensity of If it exceeds 0.5, the magnetization value becomes high, and it is difficult to adapt to the current system using non-magnetic toner. More preferably, it is 1: 0.07 to 1: 0.45.

  The Ti content of the iron-based black particle powder according to the present invention is 10.0 to 40.0 atomic% based on the total Fe. If the content is less than 10 atomic%, the magnetization value becomes high, and it is difficult to adapt to the current system using non-magnetic toner. If it exceeds 40 atomic%, the desired blackness and coloring power cannot be obtained because unreacted Ti compounds remain. More preferably, it is 12 to 35 atomic%, and still more preferably, it is 20 to 33.3 atomic%.

The saturation magnetization value of the iron-based black particle powder according to the present invention is 5 to 40 Am ² / kg. When the saturation magnetization is less than ₅ Am ² / kg, an impurity phase such as Fe ₂ TiO ₅ is easily generated, and it is difficult to easily obtain a desired blackness. If it exceeds 40 Am ² / kg, it is difficult to adapt to the current system using a non-magnetic toner, it is difficult to obtain a desired image density, and fogging is observed. Preferably it is 5-30 Am < ² > / kg, More preferably, it is 5-25 Am < ² > / kg.

The blackness L ^* of the iron-based black particle powder according to the present invention is 6 to 13. When the blackness L ^* exceeds 13, it cannot be said that the blackness is excellent, and it cannot be used as a black pigment. If it is less than 6, it cannot be produced industrially. It is preferably from 6 to 12.5, more preferably from 6 to 11.5.

  The average particle size of the iron-based black particle powder according to the present invention is 0.01 to 0.50 μm. If the average particle size is less than 0.01 μm, the desired blackness cannot be obtained. If it exceeds 0.50 μm, the desired coloring power cannot be obtained. Preferably it is 0.04 to 0.24 µm, more preferably 0.08 to 0.20 µm.

The BET specific surface area of the iron-based black particle powder according to the present invention is preferably 3 to 60 m ² / g. When the BET specific surface area value is less than 3 m ² / g, the nonmagnetic black particle powder is coarse, or the particles and the particles are sintered to form coarse particles, resulting in reduced coloring power. If it exceeds 60 m ² / g, it will be difficult to obtain a desired blackness. Preferably it is 6-30 m < ² > / g, More preferably, it is 7-20 m < ² > / g.

  The coloring power of the iron-based black particle powder according to the present invention is preferably from 35 to 45 in the case where the coloring power in the evaluation method described below is used. When the coloring power exceeds 45, it is difficult to obtain a sufficient image density when a nonmagnetic black toner using the nonmagnetic black particle powder is used. Nonmagnetic black particles having a tinting power of less than 35 cannot be produced industrially. More preferably, it is 35 to 44.

Black iron-based particles according to the present invention _2, the mixed composition of iron-based oxide having a FeTiO 3 _-Fe 2 _{O 3} solid solution or FeTiO ₃ -Fe ₂ O ₃ solid solution and spinel structure, containing a blue pigment Is preferred. By including a blue pigment, the degree of blackness and coloring power are further improved.

  The content of the blue pigment in the iron-based black particle powder according to the second aspect of the present invention is 0.1 to 20% by weight. If it is less than 0.1% by weight, the effect on blackness is small. If it exceeds 20% by weight, the hue of the blue pigment becomes close. Preferably it is 1 to 10% by weight.

The iron-based black particle powder according to the second aspect of the present invention has a composition, an average particle diameter, and a magnetization value substantially equal to those described above, and a blackness L ^* of preferably 6 to 12, more preferably 6 to 11, and coloring. The force is preferably from 30 to 43.5 when indicated by the color of the evaluation method described later.

  The blue pigment in the present invention may be a known one, and examples thereof include alkali blue, phthalocyanine blue, cobalt blue, and ultramarine blue.

  In addition, the iron-based black particle powder according to the present invention may include, in addition to iron and titanium, one or more elements selected from Mg, Al, Si, P, Mn, Co, Ni, Cu, and Zn. May be contained in an amount of 0 to 10 atomic% with respect to the total amount.

  Next, a method for producing the iron-based black particle powder according to the present invention will be described.

The iron-based black particle powder according to the present invention uses magnetite particles having a Fe2 ⁺ content of 17 to 28% by weight in terms of FeO, and coats the surface of the particles with a titanium compound. It can be obtained by calcination after heating and baking in a temperature range of 880 ° C.

When the Fe ²⁺ content of the magnetite particles in the present invention is less than 17% by weight in terms of FeO, an unnecessary phase is generated, and the blackness is reduced. Magnetite exceeding 28% by weight is difficult to produce industrially. More preferably, it is 18 to 27% by weight.

The magnetite particle powder in the present invention preferably has an average particle size of 0.007 to 0.4 μm, more preferably 0.02 to 0.20 μm, and a BET specific surface area of 3 to 80 m ² / g, more preferably 6 to 30 m ² / g.

  The magnetite particle powder can be obtained by a conventional method.For example, oxygen is added to a ferrous salt reaction solution containing a ferrous hydroxide salt colloid obtained by reacting an aqueous ferrous salt solution with an aqueous alkaline solution. It can be obtained by ventilating the contained gas.

  Examples of the titanium compound used in the present invention include titanyl sulfate, titanium tetrachloride, and titanium trioxide.

  The addition amount of the titanium compound is preferably 10 to 40 atomic% based on Fe. More preferably, it is 20 to 33.3 atomic%.

  The coating of the titanium compound on the magnetite particle powder is performed by adding the titanium compound to an aqueous suspension containing the magnetite particles and coating the surface of the magnetite particles with the titanium compound using an aqueous alkali hydroxide solution or an aqueous alkali carbonate solution. Let it. In the coating reaction, it is preferable to maintain the reaction pH immediately after the addition of the titanium compound without lowering the pH value of the reaction solution.

  When the different metal element is contained, it may be contained in the magnetite particles in advance, or a salt composed of various metal elements in an aqueous solution in which the surface of the magnetite particles is coated with a titanium compound, or various metals. A solution containing an element may be added.

  The atmosphere for heating and firing in the present invention is preferably under a non-oxidizing atmosphere, and under an oxidizing atmosphere, it is difficult to obtain iron-based black particles having a high blackness.

  The temperature range of the heating and firing in the present invention is preferably from 650 to 880 ° C., and if it is lower than 650 ° C., the solid-phase reaction between the magnetite particles and the Ti compound becomes insufficient, and the desired iron-based black particle powder may be obtained. If the temperature exceeds 880 ° C., an unnecessary phase is generated, which is not preferable. More preferably, it is 700 to 850 ° C.

  The iron-based black particle powder according to the second aspect of the present invention can be obtained by adding and mixing and pulverizing a blue pigment during the pulverization.

Black iron-based particles containing a blue pigment according to the present invention _2, a mixed composition of iron-based oxide having a FeTiO 3 _-Fe 2 _{O 3} solid solution or FeTiO ₃ -Fe ₂ O ₃ solid solution and spinel structure A blue pigment may be mixed, or may be adhered to the particle surface of FeTiO ₃ —Fe ₂ O ₃ solid solution or FeTiO ₃ —Fe ₂ O ₃ solid solution and iron-based oxide having a spinel structure. . Further, a paste may be attached to the particle surface of the iron-based black particle powder, and a blue pigment may be attached or covered via the attached paste. In addition, as the sizing agent, an organosilane compound or polysiloxane generated from alkoxysilane can be used.

  Next, a non-magnetic toner containing the iron-based black particles according to the present invention will be described.

  The black magnetic toner according to the present invention is composed of the iron-based black particles according to the present invention and a binder resin, and may contain a release agent, a colorant, a charge control agent, other additives, and the like, if necessary. .

The black non-magnetic toner has an average particle diameter of usually 3 to 15 μm, preferably 5 to 12 μm, and a magnetization value (saturation magnetization value) as low as possible, for example, usually 30 Am ² / kg or less, preferably 20 Am ² / kg or less.

  The ratio of the binder resin to the iron-based black particles is usually 0.1 to 900 parts by weight, preferably 17 to 185 parts by weight, based on 100 parts by weight of the binder resin.

  As the binder resin, a vinyl polymer obtained by polymerizing or copolymerizing a vinyl monomer such as a polyester resin, a styrene-acryl copolymer resin, styrene, an alkyl acrylate and an 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 copolymer preferably contains 50 to 95% by weight of a styrene component.

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

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

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

  As the mixer, a Henschel mixer, a ball mill or the like can be used. As the heat 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 or a jet mill, and can be performed by a known air classification or the like.

  Other methods for obtaining a black magnetic toner include a suspension polymerization method and an emulsion polymerization method. In the suspension polymerization method, the polymerizable monomer and the black magnetic iron oxide particles are further dissolved, if necessary, by adding a colorant, a polymerization initiator, a crosslinking agent, a charge control agent, and a mixture containing other additives. It is obtained by adding the dispersed monomer composition to an aqueous phase containing a suspension stabilizer while stirring, granulating, and polymerizing to obtain a desired particle size. In the emulsion polymerization method, the monomer and the non-magnetic black particles are adjusted to a desired particle size by adding an emulsifier in the process of performing polymerization by further dispersing a colorant and a polymerization initiator in water as necessary. It can be obtained by:

<Action>
It is presumed that the iron-based black particle powder according to the present invention has excellent blackness because the use of magnetite containing a large amount of Fe ²⁺ does not generate an unnecessary phase that inhibits blackness even when heat treatment is performed. are doing.

  It is presumed that the iron-based black particle powder according to the present invention has excellent blackness and low magnetization value because the amount of magnetite is reduced as much as possible.

  Furthermore, in the present invention, by mixing a blue pigment, the degree of blackness and coloring power is further improved,

  A typical embodiment of the present invention is as follows.

  The average particle diameter of each particle was measured by measuring the particle diameter of 350 particles shown in the electron micrograph, and the average value was shown.

The constituent phases of the particles were identified by X-ray diffraction (tube: Cu). _Further, FeTiO _{3 -Fe} 2 _O 3 solid solution and _Fe 3 _O 4 peak intensity ratio of _-γ-Fe 2 _{O 3} solid _{solution, Fe} 3 _{O 4} to the peak intensity of the (104) plane of FeTiO _{3 -Fe} 2 _O 3 solid solution Calculated from the peak intensity of the (220) plane of the -γ-Fe ₂ O ₃ solid solution.

  The specific surface area value was indicated by a value measured by a BET method using “Mono Sorb MS-II” (manufactured by Yuasa Ionics Co., Ltd.).

  The magnetic properties of the iron-based black particle powder are values measured under a magnetic field of 796 kA / m (10 kOe) using a “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.).

  The content of dissimilar metal elements such as Ti and Al, Si, and Cu in the iron-based black particle powder was determined by a calibration curve method using a “fluorescent X-ray analyzer RIX-2100” (manufactured by Rigaku Corporation). It was measured.

The Fe ²⁺ content was indicated by a value determined by the following chemical analysis method.

  That is, under an inert gas atmosphere, 25 cc of a mixed solution containing phosphoric acid and sulfuric acid at a ratio of 2: 1 to 0.5 g of black magnetic iron oxide particles or iron-based black particles was added, and the black magnetic iron oxide particles were added. Alternatively, the iron-based black particle powder is dissolved. After adding a few drops of diphenylamine sulfonic acid as an indicator to this diluted solution of the aqueous solution, redox titration was performed using an aqueous solution of potassium dichromate. The end point was defined as the time when the diluting liquid turned purple, and it was calculated from the amount of the aqueous solution of dichromic acid used up to the end point.

The blackness of the iron-based black particle powder was determined by kneading 0.5 g of a sample and 0.5 ml of castor oil with a Hoover-type muller to form a paste. A coated piece (coating thickness: about 30 μm) applied on paper using a 150 μm (6 mil) applicator was prepared, and the color of the coated piece was measured using a spectral colorimeter color guide (manufactured by BYK-Gardner GmbH). And JIS Z 8929, the color index (L ^* value).

The coloring power of the iron-based black particle powder is as follows. 0.5 g of a sample, 0.5 ml of castor oil and 1.5 g of titanium dioxide are kneaded with a Hoover-type muller into a paste, and 4.5 g of clear lacquer is added to the paste. A coated piece (coating thickness: about 30 μm) was prepared by coating with a 150 μm (6 mil) applicator on a cast-coated paper, and a spectral colorimeter color guide (BYK-Gardner GmbH) was prepared for the coated piece. And colorimetric index (L ^* value) according to JIS Z 8929.

  The image density using the black toner is obtained by printing solid black (A4) on the manufactured black toner using an electrophotographic printer (MICROLINE 600CL manufactured by Oki Electric Industry Co., Ltd.), and calculating the solid black image density from RD914 (product). Name, manufactured by MACBETH). The higher the value, the better the image density, and practically 1.30 or more is required.

The fog using the black toner was evaluated using the solid black (A4) used for the measurement of the blackness of the toner for electrophotography described above by visually observing the presence or absence of fog, and evaluated according to the following four grades.
：: very good (not generated)
：: good (almost no occurrence)
△: Practical (slight generation is observed)
×: Not practical

<Production of iron-based black particle powder>
Example 1
An aqueous solution containing 38.9 mol of titanyl sulfate in an aqueous suspension containing 10 kg of spherical magnetite particle powder (average particle diameter 0.15 μm, BET specific surface area 10.8 m ² / g, FeO content 25.6% by weight) (Corresponding to 30 atomic% in terms of Ti with respect to the total Fe of the magnetite particle powder). Note that NaOH was added to the mixture so that the pH of the reaction solution did not decrease during the addition. Then, after adjusting the pH value of the mixed solution to 8.0 and depositing a hydrated oxide of titanium on the surface of the magnetite particles, filtration, washing and drying are performed to coat the particle surface with the hydrated oxide of titanium. The obtained spherical black magnetic iron oxide particles were obtained.

After heating 10 kg of the spherical black magnetic iron oxide particles whose surface is coated with a hydrated oxide of titanium at 750 ° C. for 60 minutes under a N ₂ gas flow, a Simpson mix muller (Sandmill MPUV-2: Matsumoto Co., Ltd.) (Cast Iron Works) at a linear load of 30 kg / cm for 60 minutes to obtain iron-based black particle powder.

The Ti content of the obtained iron-based black particle powder was 29.9 atomic% based on the total Fe. The saturation magnetization σs was 10.5 Am ² / kg, the L ^* value representing blackness was 9.7, and the tinting strength was 40.4. The average particle size is 0.17 μm as shown in the electron micrograph of FIG. 1, and as shown in the X-ray diffraction diagram of FIG. 2, FeTiO ₃ —Fe ₂ O ₃ solid solution and Fe ₃ O ₄ —γ-Fe ₂ O ₃ It was a mixture of solid solutions. Peak intensity of (220) plane of _{Fe 3 O 4 -γ-Fe 2} O 3 with respect to (104) plane of FeTiO ₃ -Fe ₂ O ₃ was 1: 0.09.

Examples 2 to 10, Comparative Examples 2 to 7
Iron-based black particles were obtained in the same manner as in Example 1 except that the type of magnetite, the amount of the titanium compound added, and the temperature of the heating and firing treatment were variously changed.

  The production conditions at this time are shown in Table 1, and various characteristics of the obtained nonmagnetic black particle powder are shown in Table 2.

Comparative Example 1 (Additional test experiment of Example 1 in JP-A-3-2276)
100 g of granular magnetite particle powder (average particle diameter 0.2 μm, magnetization value 85.0 emu / g) is dispersed and mixed in an aqueous solution containing 0.26 mol of TiOSO ₄ (corresponding to Ti / Fe = 20.0 atomic%). Then, the mixture was neutralized by adding NaOH, and a hydroxide of Ti was deposited on the surface of the particles at pH 8, followed by filtration and drying. As a result of X-ray fluorescence analysis, the amount of Ti (IV) of the obtained granular magnetite particles having the particle surface coated with a hydroxide of Ti was 21.0 atom with respect to Fe (II) and Fe (III). %Met.

50 g of the granular magnetite particle powder having the particle surface coated with a hydroxide of Ti was calcined at 750 ° C. for 120 minutes under a N ₂ gas flow, and then pulverized to obtain a black particle powder.

The Ti content of the obtained black particle powder was 21.0 atomic% based on the total Fe. The saturation magnetization σs was 0.6 Am ² / kg, the L ^* value representing blackness was 14.1, and the tinting strength was 46.9. The average particle diameter was 0.25 μm, and as shown in the X-ray diffraction diagram of FIG. 3, it was a mixture of Fe ₂ O ₃ —FeTiO ₃ solid solution and Fe ₂ TiO ₅ .

  The production conditions at this time are shown in Table 1, and various properties of the obtained iron-based black particle powder are shown in Table 2.

In Comparative Examples 5 and _6, in addition to mixed composition of Fe ₂ O ₃ -FeTiO 3 and _{Fe 3 O 4 -γ-Fe 2} O 3, Ti unreacted compound remained.

Examples 11 to 15
Non-magnetic black particle powders were obtained in the same manner as in Examples 2 to 6, except that each blue pigment was added during the pulverization treatment in Examples 2 to 6.

  Table 3 shows the production conditions at this time and various characteristics of the obtained iron-based black particle powder.

<Manufacture of electrophotographic toner>
Example 16
A composition obtained by mixing the iron-based black particle powder obtained in Example 1 with a Henschel mixer at the following mixing ratio is melt-kneaded using a twin-screw extruder (trade name: S-1 manufactured by Kurimoto Iron & Steel Co., Ltd.). Then, the kneaded product was cooled and then pulverized. This was classified into a volume average particle diameter of 8 to 10 μm (trade name, manufactured by Coal Counter Co., Ltd .: measured by Multisizer), and 100 parts by weight of the obtained toner powder was added to hydrophobic silica fine powder (trade name, manufactured by Aerosil Japan Co., Ltd.) : RX-200) 0.5 parts by weight was externally added to obtain an electrophotographic toner.

100 parts by weight of a styrene-acrylic copolymer resin,
(Hymer SB-308: manufactured by Sanyo Chemical Industries, Ltd.)
25 parts by weight of iron-based black particle powder,
0.5 parts by weight of negative charge control agent,
(BONTRON E-84: manufactured by Orient Chemical Co., Ltd.)
5 parts by weight of low molecular weight wax.
(Viscole 550-P: manufactured by Sanyo Chemical Industries, Ltd.)

  The obtained electrophotographic toner had an initial image density of 1.45 and no fogging (◎ out of four levels).

Examples 17 to 30, Comparative Examples 9 to 15
A non-magnetic toner was obtained in the same manner as in Example 16 except that the type of the non-magnetic black particle powder was variously changed.

  Table 4 shows the processing conditions and various characteristics of the obtained non-magnetic black toner.

  The iron-based black particle powder according to the present invention is excellent in blackness and has as low a magnetization value as possible, and thus is suitable as a pigment and a paint exhibiting black, a coloring material for a resin composition, a filler, and the like.

The black non-magnetic toner produced by using the iron-based black particle powder according to the present invention has a high degree of blackness and a low magnetization value, and thus is suitable as a non-magnetic toner.

3 is an electron micrograph of the nonmagnetic black particle powder obtained in the embodiment of the present invention. (Magnification 20000) 4 is an X-ray diffraction pattern of the non-magnetic black particle powder obtained in the embodiment of the present invention. 5 is an X-ray diffraction pattern of the non-magnetic black particle powder obtained in Comparative Example 1.

Claims (3)

It is composed of a FeTiO ₃ —Fe ₂ O ₃ solid solution or a mixed composition of a FeTiO ₃ —Fe ₂ O ₃ solid solution and an iron-based oxide having a spinel structure, and the Ti content is 10.0 to less than the total Fe in terms of Ti. 40.0 at%, a saturation magnetization value of 5 to 40 Am ² / kg, a blackness L ^* value of 6 to 13, and an average particle size of 0.01 to 0.50 μm. Iron-based black particle powder. _{(1) FeTiO 3 -Fe 2 O} 3 solid solution or FeTiO ₃ -Fe ₂ O ₃ mixed composition of iron-based oxide having a solid solution and spinel structure 80 to 99.9 weight and (2) Blue pigment 0.1 -20 wt.%, The Ti content is 10.0-40.0 atomic% in terms of Ti with respect to the total Fe, the saturation magnetization value is 5-40 Am ² / kg, and the blackness L ^* value is 6 To 13 and an average particle diameter of 0.01 to 0.50 μm. A black toner using the iron-based black particle powder according to claim 1 or 2.

Images