JP4868111B2 - Iron-based black particle powder for toner - Google Patents

Description

  The present invention provides an iron-based black particle powder for toner that is excellent in coloring power and has a magnetization value as low as possible.

  The iron-based black particle powder according to the present invention can be used as a pigment and paint exhibiting black color, a coloring material for a resin composition, and the like, particularly when used in a non-magnetic black toner. Due to the excellent dispersibility of the black particle powder in the product, it is possible to provide a non-magnetic black toner that has high coloring power and exhibits stable chargeability even in a high temperature and high humidity environment.

  Black pigments such as magnetite particle powder, ilmenite particle powder, and carbon black have long been widely used as colorants for paints, printing inks, cosmetics, rubber / resin compositions, and the like.

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

  However, since magnetite particles have magnetism, they tend to be magnetically aggregated between the particles, and it is difficult to say that they are excellent in dispersibility.

  Recently, with the increase in the speed and image quality of laser beam printers and digital copying machines, there has been a strong demand for improving the characteristics of black toner as a developer. For this purpose, black toner has sufficient blackness. It is strongly required to have it.

  Furthermore, in recent years, full-color printing has been promoted, and non-magnetic toner is used as a corresponding printer or copying machine.

  Therefore, there is a demand for black toner that is non-magnetic or has a magnetization value as small as possible and can be adapted to the current system.

  As described above, improvement of various characteristics of the black nonmagnetic toner is strongly demanded. In black nonmagnetic toner, it is known that the characteristics of the black pigment contained in the toner have a great influence on the development characteristics, and various characteristics of the black nonmagnetic toner are mixed and dispersed in the black nonmagnetic toner. There is a close relationship with various characteristics of black pigments, and there is a strong demand for further improvements in characteristics of black pigments used in black nonmagnetic toners.

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

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

  Therefore, there is a demand for black particle powder that is excellent in blackness and has a magnetization value as low as possible and excellent dispersion in a resin composition.

Conventionally, ilmenite particle powder obtained by hydrothermal treatment (Patent Document 1) as a black iron-based particle powder, and a black pigment comprising a mixed composition of Fe ₂ TiO ₅ and Fe ₂ O ₃ —FeTiO ₃ solid solution (Patent Document 2), black complex oxide (Patent Documents 3 and 4), Fe ₂ O ₃ —FeTiO ₃ solid solution or Fe ₂ having a specific BET specific surface area value (nitrogen adsorption method) and a low saturation magnetization value An iron-based black particle powder (Patent Document 5) having a mixed composition of an O ₃ —FeTiO ₃ solid solution and an iron-based oxide having a spinel structure is known.

JP-A-1-298028 JP-A-3-2276 JP 2003-15362 A JP 2004-151699 A JP 2004-161608 A

  An iron-based black particle powder that is excellent in coloring power and has a magnetization value as low as possible is currently most demanded, but has not yet been obtained.

That is, Patent Document 1 describes that Ti ³⁺ is used to obtain ilmenite particle powder having a uniform particle size by hydrothermal treatment, but it is produced by hydrothermal treatment and is hardly industrial.

The non-magnetic particle powder described in the above-mentioned Patent Document 2 contains Fe ₂ TiO ₅ and thus has a low magnetization value. However, the surface hydroxyl group is not taken into consideration, the coloring power is low, and the blackness is low. It is hard to say that you are satisfied.

  The black complex oxides described in Patent Documents 3 and 4 do not take into account the surface hydroxyl groups, and are difficult to say that the coloring power is low and the blackness is satisfied.

  The iron-based black particle powder described in Patent Document 5 is not considered with respect to the surface hydroxyl groups of the particles, and it is difficult to say that the coloring power is sufficient.

  Then, this invention makes it a technical subject to obtain the iron-type black particle powder which is excellent in coloring power, and has a low magnetization value.

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

That is, the ratio (S _H2O / S _N2 ) of the specific surface area value (S _H2O ) by water vapor adsorption and the specific surface area value (S _N2 ) by nitrogen adsorption is 0.75 to 1.25, and the saturation magnetization value is 5 Am ^2. It is an iron-based black particle powder for toner, comprising iron-titanium composite oxide particle powder of less than / kg (Invention 1).

Further, in the present invention, the ratio (S _H2O / S _N2 ) of the specific surface area value (S _H2O ) by water vapor adsorption and the specific surface area value (S _N2 ) by nitrogen adsorption is 0.80 to 1.00, and saturated magnetization It is an iron-based black particle powder for toner, characterized by comprising an iron-titanium composite oxide particle powder having a value of less than 5 Am ² / kg (Invention 2).

Further, according to the present invention, in the iron-titanium composite oxide particle powder of the present invention 1 or 2, the water vapor adsorption amount per unit area (V _0.6 -V) when the relative pressure is between _{0.3 and 0.6. 0.3} ) is an iron-based black particle powder for toner, which is 0.3 mg / m ² or less (Invention 3).

  The present invention also provides the iron-based black particles for toner according to any one of the present inventions 1 to 3, wherein the iron-titanium composite oxide particle powder has an average particle size of 0.05 to 0.40 μm. It is a powder (Invention 4).

  The present invention also provides an iron-based black particle powder for toner according to any one of the first to fourth iron-titanium composite oxide particles according to the present invention, wherein the Ti content is 10 to 38 atomic%. There is (Invention 5).

According to the present invention, in the iron-titanium composite oxide particle powder according to any one of the present invention 1 to 5, the constituent phase has at least a FeTiO ₃ —Fe ₂ O ₃ solid solution. It is a particle powder (Invention 6).

Further, the present invention is the iron-titanium composite oxide particle powder of the present invention 6, further comprising an iron-based oxide having a spinel structure and / or Fe ₂ TiO _5. It is a powder (Invention 7).

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

  The black toner using the iron-based black particle powder according to the present invention has a high coloring power due to its excellent dispersibility in the resin composition, and also exhibits a stable chargeability even in a high-temperature and high-humidity environment. be able to.

  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.

The iron-based black particle powder according to the present invention has a ratio (S _H2O / S _N2 ) of a specific surface area value (S _H2O ) by water vapor adsorption and a specific surface area value (S _N2 ) by nitrogen adsorption to 0.75 to 1.25. It is. When S _H2O / S _N2 is less than 0.75, the amount of surface hydroxyl groups of the particles is reduced, and when S _H2O / S _N2 is greater than 1.25, the amount of surface hydroxyl groups is larger than necessary. Therefore, when the resin composition is formed, the dispersibility in the resin is deteriorated, so that a desired coloring power cannot be obtained. Preferably it is 0.82-1.00, More preferably, it is 0.80-1.00.

The specific surface area value (S _H2O ) by water vapor adsorption of the iron-based black particle powder according to the present invention is preferably 2.25 to 18.75.

The specific surface area value (S _N2 ) by nitrogen adsorption of the iron-based black particle powder according to the present invention is preferably 3 to 15 m ² / g. When the BET specific surface area value is less than 3 m ² / g, the iron-based black particle powder is coarse or becomes coarse particles in which the particles and particles are sintered together, and the coloring power is reduced. When it exceeds 15 m ² / g, it becomes difficult to obtain a desired blackness. More preferably, it is 6-14 m < ² > / g, More preferably, it is 6.5-13 m < ² > / g.

The iron-based black particle powder according to the present invention has a water vapor adsorption amount per unit area (V _0.6 -V _0.3 ) of 0.3 mg / m ² or less when the relative pressure is between _{0.3 and 0.6.} It is preferable that When the toner is produced using iron-based black particle powder exceeding 0.3 mg / m ² , the charging performance in a high temperature and high humidity environment is inferior, which is not preferable. More preferably, it is 0.28 mg / m ² or less.

The saturation magnetization value of the iron-based black particle powder according to the present invention is less than 5 Am ² / kg. When the saturation magnetization value exceeds 5 Am ² / kg, it is difficult to easily adapt to the current system using non-magnetic toner, it becomes difficult to obtain a desired image density, and the possibility of fogging is high. Become. Preferably, it is 4.5 Am ² / kg or less.

  The average particle diameter of the iron-based black particle powder according to the present invention is preferably 0.05 to 0.40 μm. When the average particle size is less than 0.05 μm, desired blackness cannot be obtained. If it exceeds 0.40 μm, the desired coloring power cannot be obtained. Preferably it is 0.08-0.35 micrometer, More preferably, it is 0.10-0.32 micrometer.

  The titanium content of the iron-based black particle powder according to the present invention is preferably 10 to 38 atomic%.

Examples of the constituent phase of the iron-based black particle powder according to the present invention include FeTiO ₃ —Fe ₂ O ₃ solid solution, Fe ₂ TiO ₅ , Fe ₂ TiO ₄ —Fe ₃ O ₄ solid solution, FeTiO ₃ , Fe ₂ TiO _{4 and the} like. Or a mixture of two or more of the above compounds. Also, _Fe 3 _{O 4} and a raw material, spinel iron oxide such as _γ-Fe 2 _{O 3} may be present.

  The coloring power of the iron-based black particle powder according to the present invention is preferably 35 to 44 when indicated by the color development of the evaluation method described later. When the coloring power exceeds 44, it is difficult to obtain a sufficient image density when the non-magnetic black toner using the iron-based black particle powder is used. Iron-based black particle powder having a coloring power of less than 35 cannot be produced industrially. More preferably, it is 35-43.

  The iron-based black particle powder according to the present invention contains one or more elements selected from Mg, Al, Si, P, Mn, Co, Ni, Cu and Zn in addition to iron and titanium. It may be contained in an amount of 0 to 10 atomic% based on 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 can be obtained by firing and firing titanium-containing magnetite particles in a non-oxidizing atmosphere at a temperature range of 650 to 850 ° C.

  The titanium-containing magnetite particle powder is obtained, for example, by aerating an oxygen-containing gas to a ferrous salt reaction solution containing a ferrous hydroxide colloid obtained by reacting a ferrous salt aqueous solution and an alkaline aqueous solution. In the production method for obtaining magnetite, a titanium compound may be added to a ferrous salt reaction solution containing a ferrous hydroxide colloid while an oxygen-containing gas is being passed.

  The aqueous ferrous salt solution used in the present invention is preferably an aqueous iron sulfate solution.

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

  The titanium compound is preferably added simultaneously with the addition of the titanium compound by adding an alkali hydroxide aqueous solution, an alkali carbonate aqueous solution or the like to maintain the pH value of the aqueous suspension at 6.0 or more.

  In the present invention, the surface of the titanium-containing magnetite particles may be further coated with a titanium compound.

  The titanium-containing magnetite particle powder is coated with a titanium compound by adding an aqueous alkali hydroxide solution, an aqueous alkali carbonate solution, or the like to the water suspension containing the titanium-containing magnetite particles before adding the titanium compound. At the same time as the addition, an aqueous alkali hydroxide solution, an aqueous alkali carbonate solution or the like is preferably added to maintain the pH value of the aqueous suspension.

The titanium content of the titanium-containing magnetite particle powder is preferably 10 to 38 atomic%. When it is out of the above range, the number of sintered parts due to heat treatment increases and the coloring power decreases. More preferably, it is 12-33.3 atomic%.
The magnetite particles preferably contain at least 3 atomic% or more of titanium. If it is less than 3 atomic%, the number of sintered parts due to the heat treatment increases and the coloring power decreases. More preferably, it is 5 atomic% or more.

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

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

  The temperature range of the heating and baking in the present invention is preferably 650 to 850 ° C. When the temperature range is less than 650 ° C., the solid phase reaction between the magnetite particles and the Ti compound becomes insufficient, and the intended iron-based black particle powder can be obtained. It is difficult, and when it exceeds 850 ° C., an unnecessary phase is generated, which is not preferable. More preferably, it is 680-830 degreeC.

  What is necessary is just to grind | pulverize the particle powder after heat-firing by a conventional method.

<Action>
In recent years, binder resins for toners tend to introduce hydrophilic functional groups in order to improve fixability. In the present invention, it is found that there is a close correlation between the amount of hydroxyl groups on the pigment surface, that is, the degree of water vapor adsorption and the dispersion of the pigment in the toner, in order to suitably use the pigment in the toner binder resin. It was. That is, if the surface hydroxyl group amount of the pigment is too small or too large, the dispersibility in the resin composition will be poor.
Therefore, in the present invention, the specific surface area value (S _H2O ) by water vapor adsorption of the iron-based black particle powder is measured, and the specific surface area value (S _H2O ) by water vapor adsorption and the specific surface area value (S _N2 ) by nitrogen adsorption method are used. The iron-based black particle powder having high coloring power and stable chargeability even in a high-temperature and high-humidity environment by being excellent in dispersibility in the resin composition by controlling the ratio of It is what.

  The iron-based black particle powder according to the present invention has low magnetization and excellent coloring power because the reactivity during heat treatment increases and the heat treatment can be performed at a lower temperature. The inventor presumes that the remaining granular iron-based black particle powder could be obtained.

  The reason why the saturation magnetization value of the iron-based black particle powder according to the present invention is low is that, by including a titanium compound in the magnetite, the reactivity of the magnetite and the titanium compound during the heat treatment is increased, so that unreacted The inventor presumes that the residual amount of the magnetite component is as low as possible.

  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 particle diameter was indicated.

The specific surface area value (S _N2 ) by nitrogen adsorption was shown as a value measured by the BET method by N ₂ adsorption using “Mono Sorb MS-II” (manufactured by Yuasa Ionics Co., Ltd.).

The specific surface area value (S _H2O ) by water vapor adsorption was degassed for 2 hours at 120 ° C. using a “water vapor adsorption device BELSORP18” (manufactured by Nippon Bell Co., Ltd.) at 25 ° C. The water vapor adsorption isotherm was measured at the adsorption temperature, and indicated by a value measured by the BET method in a relative pressure range of 0.05 to 0.30.

The water vapor adsorption amount per unit area (V _0.6 -V _0.3 ) is a value obtained from the water vapor adsorption amount difference between the relative pressures 0.30 and 0.60 on the water vapor adsorption isotherm measured above. It was.

  The constituent phases of the particles were identified using “X-ray diffractometer RINT-2500” (manufactured by Rigaku Corporation, tube: Cu).

  The magnetic characteristics 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 Industry Co., Ltd.).

  The content of Ti in the iron-based black particle powder was measured by a calibration curve method using a “fluorescence X-ray analyzer RIX-2100 type” (manufactured by Rigaku Corporation).

  The gloss representing the dispersibility of the iron-based black particle powder is obtained by kneading 0.5 g of a sample and 0.5 ml of castor oil with a Hoover-type Mahler to form a paste, adding 4.5 g of clear lacquer to this paste, and kneading it into a paint. Then, a coated piece (coating thickness: about 30 μm) coated on a cast-coated paper using a 150 μm (6 mil) applicator is prepared, and a digital gonio-gloss meter (made by UGV-5D Suga Test Instruments) is used for the coated piece. The light reflectance (%) measured at an incident angle of 60 °.

The coloring power of the iron-based black particle powder is as follows: 0.5 g of sample, 0.5 ml of castor oil and 1.5 g of titanium dioxide are kneaded with a Hoover type Mahler to form a paste, and 4.5 g of clear lacquer is added to this paste, kneading, An application piece (coating thickness: about 30 μm) was prepared by applying a 150 μm (6 mil) applicator on cast-coated paper, and a spectrocolorimeter color guide (manufactured by BYK-Gardner GmbH) was applied to the application piece. The color was used and measured, and the color index (L ^* value) was indicated according to JIS Z 8729.

Example 1
<Manufacture of iron-based black particle powder>
17.8 L of a 1.8 mol / L ferrous sulfate aqueous solution was added to 22.2 L of a 2.76 N NaOH solution to obtain a reaction solution containing a total amount of 40 L and a pH 6.5 iron hydroxide colloid. Thereafter, the temperature of the reaction solution was raised to 90 ° C., air was passed through for 100 minutes, and 20 L of a 0.48 mol / L titanyl sulfate aqueous solution was added to form a black precipitate. During this time, the temperature was maintained at 90 ° C. and pH 6.5.
The black precipitate was separated by filtration, washed with water, dried at 60 ° C., further heated and fired at 730 ° C. under a N ₂ gas flow, and then pulverized to obtain iron-based black particle powder.

The resulting black particles were _is a _{S H2 O} is 11.9m ² / _{g, S N2} is ^{_{12.8m 2 / g, S H2O /}} S N2 is 0.93, the relative pressure is 0. The water vapor adsorption amount per unit area (V _0.6 −V _0.3 ) between 3 and _0.6 was 0.19 mg / m ² . The saturation magnetization value σs was 1.2 Am ² / kg, the average particle size was 0.11 μm, and the titanium content with respect to the total iron was 29.7 atomic%. The gloss was 82%, and the L ^* value representing the tinting strength was 39.2. The constituent phase was FeTiO ₃ —Fe ₂ O ₃ solid solution.

Examples 2 and 3
An iron-based black particle powder was obtained in the same manner as in Example 1 except that the type and addition amount of the titanium compound, the pH of the reaction solution, and the temperature of the heat treatment were varied.

Example 4
In the same manner as in Example 1, a reaction solution containing an iron hydroxide colloid having a total amount of 40 L and a pH of 6.5 was obtained. Thereafter, the temperature of the reaction solution was raised to 90 ° C., and air was passed through for 100 minutes, and 3.3 L of 0.48 mol / L titanyl sulfate aqueous solution was added to form a black precipitate. During this time, the temperature was maintained at 90 ° C. and pH 6.5.
Subsequently, 16.7 L of 0.48 mol / L titanyl sulfate aqueous solution was added to the aqueous solution containing this black precipitate. In addition, NaOH was added to this aqueous solution so that the pH of the aqueous solution at the time of addition was maintained at 8.5 or more. Thereafter, the pH of the aqueous solution was adjusted to 8.0.
The black particle powder coated with the hydrated titanium oxide was filtered, washed with water, dried, further heated and fired at 790 ° C. under a N ₂ gas flow, and then pulverized to obtain iron-based black particle powder.

The obtained iron-based black particle powder has SH ² _O of 4.3 m ² / g, S _N2 of 5.2 m ² / g, S _H2O / S _N2 of 0.84, and a relative pressure of The amount of water vapor adsorbed per unit area (V _0.6 -V _0.3 ) between _{0.3 and 0.6} was 0.22 mg / m ² . The saturation magnetization value σs was 4.7 Am ² / kg, the average particle size was 0.22 μm, and the titanium content with respect to the total iron was 29.9 atomic%. The gloss was 78%, and the L ^* value representing the coloring power was 42.9. The constituent phase was a mixture of FeTiO ₃ —Fe ₂ O ₃ solid solution and Fe ₃ O ₄ —γ-Fe ₂ O ₃ solid solution.

Examples 5 and 6
The same as in Example 4 except that the type and amount of the titanium compound added at the time of magnetite formation, the pH of the reaction solution, the type and amount of the titanium compound used for the coating treatment, and the temperature of the heating and firing treatment were variously changed. Thus, iron-based black particle powder was obtained.

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

Comparative Example 1
17.8 L of a 1.8 mol / L ferrous sulfate aqueous solution was added to 22.2 L of a 2.76 N NaOH solution to obtain a reaction solution containing an iron hydroxide colloid having a total amount of 40 L and pH 6.5. Thereafter, the temperature of the reaction solution was raised to 90 ° C., and air was passed through for 100 minutes to produce a black precipitate. During this time, the temperature was maintained at 90 ° C. and pH 6.5.
Next, 20 L of a 0.48 mol / L aqueous solution of titanyl sulfate was added to the aqueous solution containing the black precipitate. In addition, NaOH was added to this aqueous solution so that the pH of the aqueous solution at the time of addition was maintained at 8.5 or more. Thereafter, the pH of the aqueous solution was adjusted to 8.0.
The black particle powder coated with the hydrated titanium oxide was filtered off, washed with water, dried, heated and fired at 730 ° C. under N ₂ gas flow, and then pulverized to obtain iron-based black particle powder.

The obtained black particle powder has S _H2O of 10.8 m ² / g, S _N2 of 10.3 m ² / g, S _H2O / S _N2 of 1.05, and a relative pressure of 0.00. The amount of water vapor adsorbed per unit area (V _0.6 -V _0.3 ) between 3 and _0.6 was 0.25 mg / m ² . The saturation magnetization value σs was 14.3 Am ² / kg, the average particle size was 0.15 μm, and the titanium content with respect to the total iron was 29.8 atomic%. The gloss was 69%, and the L ^* value representing the coloring power was 44.8. The constituent phase was a mixture of FeTiO ₃ —Fe ₂ O ₃ solid solution and Fe ₃ O ₄ —γ-Fe ₂ O ₃ solid solution.

Comparative Example 2
The black particle powder coated with the hydrated titanium oxide obtained in the same manner as in Comparative Example 1 was heated and fired at 810 ° C. under N ₂ gas flow, and then pulverized to obtain iron-based black particle powder.

The resulting black particle powder has an S _H2O of 1.8 m ² / g, a S _N2 of 3.2 m ² / g, a S _H2O / S _N2 of 0.56, and a relative pressure of 0.8. The amount of water vapor adsorption per unit area (V _0.6 -V _0.3 ) between 3 and _0.6 was 0.15 mg / m ² . The saturation magnetization value σs was 3.8 Am ² / kg, the average particle size was 0.43 μm, and the titanium content relative to the total iron was 29.8 atomic%. The gloss was 71%, and the L ^* value representing the coloring power was 50.1. The constituent phase was a mixture of FeTiO ₃ —Fe ₂ O ₃ solid solution, Fe ₃ O ₄ —γ-Fe ₂ O ₃ solid solution and Fe ₂ TiO ₅ .

Comparative Example 3
30 L of 0.48 mol / L titanyl sulfate aqueous solution was added to the aqueous solution containing the black precipitate obtained in the same manner as in Comparative Example 1. In addition, NaOH was added to this aqueous solution so that the pH of the aqueous solution at the time of addition was maintained at 8.5 or more. Thereafter, the pH of the aqueous solution was adjusted to 8.0.
The black particle powder coated with the hydrated titanium oxide was filtered off, washed with water, dried, heated and fired at 730 ° C. under N ₂ gas flow, and then pulverized to obtain iron-based black particle powder.

The obtained black particle powder has S _H2O of 19.2 m ² / g, S _N2 of 14.8 m ² / g, S _H2O / S _N2 of 1.30, and a relative pressure of 0. The amount of water vapor adsorbed per unit area (V _0.6 -V _0.3 ) between 3 and _0.6 was 0.35 mg / m ² . The saturation magnetization value σs was 1.1 Am ² / kg, the average particle size was 0.11 μm, and the titanium content with respect to the total iron was 44.9 atomic%. The gloss was 64%, and the L ^* value representing the coloring power was 48.9. The constituent phase was FeTiO ₃ —Fe ₂ O ₃ solid solution.

  It is clear that all of the iron-based black particle powders according to the present invention have a glossiness of 75% or more and are excellent in dispersibility.

Example 1
<Manufacture of toner for electrophotography>
Using the iron-based black particle powder obtained in Example 1, the composition mixed by the Henschel mixer at the following mixing ratio was melt-kneaded using a biaxial extrusion kneader (trade name: S-1 manufactured by Kurimoto Steel). The kneaded product was cooled and then finely pulverized. This was classified into a volume average particle diameter of 8 to 10 μm (trade name manufactured by Colecounter, Inc., measured by Multisizer). : RX-200) 0.5 part by weight was externally added to obtain an electrophotographic toner.

100 parts by weight of styrene-acrylic copolymer resin,
(Heimer SB-308: 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.
(Biscol 550-P: Sanyo Chemical Industries, Ltd.)

  The obtained electrophotographic toner had an initial image density of 1.55 and no fogging (◎ out of 4 steps).

Example 2
A nonmagnetic toner was obtained in the same manner as in Use Example 1 except that the black particle powder was changed to that obtained in Comparative Example 1.

  Table 3 shows the treatment conditions and various characteristics of the obtained nonmagnetic black toner.

  Since the iron-based black particle powder according to the present invention has a high coloring power and a magnetization value as low as possible, it is suitable as a pigment and paint exhibiting black, a coloring material for a resin composition, a filler, and the like.

The black toner using the iron-based black particle powder according to the present invention has a high coloring power due to its excellent dispersibility in the resin composition, and also exhibits a stable chargeability even in a high-temperature and high-humidity environment. be able to.

Claims (7)

An iron-based black particle powder for toner comprising a titanium-titanium composite oxide particle powder obtained by heating and firing titanium-containing magnetite particles in a temperature range of 650 to 850 ° C. in a non-oxidizing atmosphere, The ratio (S _H2O / S _N2 ) of the specific surface area value (S _H2O ) due to water vapor adsorption and the specific surface area value (S _N2 ) due to nitrogen adsorption of the iron-based black particle powder is 0.75 to 1.25, and is saturated toner for black iron-based particles which magnetization is characterized and der than 5am 2 / ^kg Turkey. An iron-based black particle powder for toner comprising a titanium-titanium composite oxide particle powder obtained by heating and firing titanium-containing magnetite particles in a temperature range of 650 to 850 ° C. in a non-oxidizing atmosphere, The ratio (S _H2O / S _N2 ) of the specific surface area value (S _H2O ) by water vapor adsorption and the specific surface area value (S _N2 ) by nitrogen adsorption of the iron-based black particle powder is 0.80 to 1.00 and is saturated toner for black iron-based particles which magnetization is characterized and der than 5am 2 / ^kg Turkey. 3. The iron-titanium composite oxide particle powder according to claim 1, wherein the water vapor adsorption amount per unit area (V _0.6 −V _0.3 ) is 0 when the relative pressure is between _{0.3 and 0.6.} An iron-based black particle powder for toner, which is ³ mg / m ² or less. In iron-titanium composite oxide particles of any crab of claims 1 to 3, toner for black iron-based particles, wherein the average particle diameter of 0.05～0.40Myuemu. In iron-titanium composite oxide particles of any crab of claims 1 to 4, toner for black iron-based particles, wherein the Ti content is 10 to 38 atomic%. In iron-titanium composite oxide particles of any crab of claims 1 to 5, a toner for black iron-based particles, characterized in that the configuration phase has at least FeTiO ₃ -Fe ₂ O ₃ solid solution. The iron-based black particle powder for toner according to claim 6, further comprising an iron-based oxide having a spinel structure and / or Fe ₂ TiO ₅ .