JP3551204B2 - Black magnetic iron oxide particle powder - Google Patents

Description

【００８９】
【表２】

【００９０】
＜黒色磁性酸化鉄粒子粉末の疎水化処理＞
実施例１２〜１５；
【００９１】
実施例１２
実施例１で得られた磁化値σ_１０００が３５．０Ａｍ ^２ ／ｋｇ、帯電量が−２０μＣ／ｇであり、Ｌ^＊値が１８、ａ^＊値が＋０．５である黒色磁性酸化鉄粒子粉末１０ｋｇをシンプソンミックスマーラー（サンドミルＭＰＵＶ−２：（株）松本鋳造鉄工所製）に投入し、シランカップリング剤（γ−クロロプロピルトリメトキシシラン：Ａ−１４３：日本ユニカー製）を１００ｇを添加してで線荷重３０ｋｇ／ｃｍで６０分間処理した。
【００９２】
得られた疎水化処理された黒色磁性酸化鉄粒子粉末は、磁化値σ_１０００が３４．５Ａｍ ^２ ／ｋｇ、帯電量が−５５μＣ／ｇであり、Ｌ^＊ 値が１７、ａ^＊ 値が＋０．５であった。
【００９３】
実施例１３〜１５
疎水化処理剤の種類を変えた以外は実施例１２と同様にして疎水化処理された黒色磁性酸化鉄粒子粉末を得た。
【００９４】
この時の諸特性を表３に示す。
【００９５】
【表３】

【００９６】
【発明の効果】
本発明に係る黒色磁性酸化鉄粒子粉末は、前出実施例にも示す通り、磁化値σ_１０００が小さく、しかも、負の帯電量が大きく、黒色度に優れている黒色磁性酸化鉄粒子粉末であるから、樹脂中への分散性にも優れているので、負に帯電させる磁性トナー用、磁性キャリア用材料粒子粉末として好適である。
【００９７】
また、本発明に係る黒色磁性酸化鉄粒子粉末は、磁性トナー中に含まれる磁性酸化鉄粒子粉末の含有量を多くすることができるので、高濃度現像及び高解像度の負に帯電させる磁性トナー用材料粒子粉末として好適である。
【００９８】
また、本発明に係る黒色磁性酸化鉄粒子粉末は、黒色度に優れているから塗料用、印刷インキ用、ゴム・プラスチック用の黒色着色顔料粉末としても使用できる。
【図面の簡単な説明】
【図１】磁性酸化鉄粒子粉末のチタン化合物の含有量と磁化値σ_１０００との関係を示す図である。
【図２】磁性酸化鉄粒子粉末のチタン化合物の含有量と帯電量との関係を示す図である。[0001]
[Industrial applications]
The invention uses a magnetic field79.58 kA / m (1 kOe)Magnetization value at₁₀₀₀(Hereinafter, simply “magnetization value σ₁₀₀₀" The present invention relates to a black magnetic iron oxide particle powder having a small negative charge amount, a large negative charge amount, and excellent blackness.
[0002]
The main use of the black magnetic iron oxide particles according to the present invention is as material particles for magnetic toners and magnetic carriers.
[0003]
[Prior art]
Black magnetic iron oxide particles are widely used as black colored pigment powders for paints, printing inks, rubbers and plastics because of their black color.
[0004]
In addition, magnetite particles among black magnetic iron oxide particles are ferromagnetic particles. Therefore, by mixing and dispersing them in resin to form composite particles, material particles for magnetic toner for electrostatic copying are used. And as a material particle powder for magnetic carriers.
[0005]
In any of the above-mentioned fields, there is no end to the demand for higher performance and higher quality, and there is a strong demand for improving the properties of the particle powder, especially for having good dispersibility in resin.
[0006]
The magnetite particle powder as the material particle powder for the magnetic toner must have a good mixing property with the resin (‥‥ VII) described in JP-A-55-65406.Normally, the particle size of the toner is several tens μm or less. The degree of microscopic mixing is important for the characteristics of the toner.
[0007]
Regarding the magnetite particle powder as the material particle powder for the magnetic carrier, JP-A-61-53660 discloses "{according to the present invention}, the dispersibility of the primary particles is improved, and the magnetic powder is uniformly dispersed. The difference in chargeability and magnetic properties between the magnetic developer particles is reduced.
[0008]
Usually, the magnetite particle powder is produced by a so-called wet method, which is produced directly from an aqueous solution.
[0009]
The wet method means that a suspension containing an Fe-containing precipitate obtained by mixing an aqueous ferrous salt solution such as ferrous sulfate and an alkaline aqueous solution such as sodium hydroxide and sodium carbonate is mixed at 60 to 100 ° C. (Japanese Patent Publication No. 44-668, etc.).
[0010]
However, the magnetite particle powder obtained by the above wet method has a magnetization value σ₁₀₀₀Is 50-75Am ² / KgAnd magnetic cohesion easily occurs, which is an obstacle to improvement in dispersibility.
[0011]
Therefore, in order to further improve the dispersibility in the resin, the magnetization value σ₁₀₀₀There is a strong demand for magnetite particle powder having a small particle size. In particular, when magnetite particle powder is used as a material powder for a magnetic toner, the magnetization value σ is required to achieve high image quality.₁₀₀₀There is a strong demand for magnetite particle powder having a small particle size. This fact will be described below.
[0012]
As electrostatic copying machines have become smaller and have higher performance such as higher speed, there has been a strong demand for magnetic toners that can improve the properties of magnetic toners, that is, high-density development and high resolution.
[0013]
The properties of the magnetic toner are closely related to the properties of the magnetic particles contained in the resin.To enable high-density development, the content of the magnetic particles contained in the resin must be increased. However, if the content of the magnetic particle powder is increased, the magnetic toner remains as an aggregate on the latent image after development due to the magnetic aggregation of the magnetic particle powder, and the fine latent image is faithfully reproduced. It is difficult to obtain high resolution.
[0014]
This fact is described in Japanese Unexamined Patent Publication No. 4-184354, "‥‥ A toner which is faithful to a signal and faithful to an original, that is, faithful to a latent image and developed at a high density is required. However, it is difficult to satisfy such advanced requirements using a toner containing a magnetic substance.For example, if the content of the magnetic substance is simply increased by increasing the coloring power of the magnetic toner to obtain a high density, The image quality deteriorates and high resolution cannot be satisfied, because the size of the spike is related to the magnetic force of the toner, and the spike increases as the magnetic material increases. Tends to remain as agglomerates due to cohesion on the latent image after toner development, making it difficult to faithfully reproduce a fine latent image. Reduced content of Although it is conceivable to reduce the magnetic cohesive force, in addition to the decrease in the coloring power, a decrease in developability due to an increase in the amount of charge and a decrease in toner production efficiency may occur. It is possible to improve, but it is also difficult to put it into practical use, especially because it may worsen the environmental dependency. 依存 Therefore, some proposals have been made to adjust the magnetic force to obtain high-performance toner. ‥‥ ”and ‥‥ 適当 ‥‥ ‥‥ ‥‥ ‥‥ 適当 適当 適当 適当 適当 適当 適当 ‥‥ 適当 適当 適当 適当 適当 ‥‥ 適当 再現. で ‥‥ で 再現 ‥‥ 線 再現 再現 ‥‥ 再現 再現. It is as described.
[0015]
Therefore, in order to obtain a magnetic toner capable of high-density development and high resolution, even if the content of the magnetic particle powder contained in the resin is large, magnetic cohesive force does not occur even if the content of the magnetic particle powder is large. Magnetization value σ₁₀₀₀Is required to be as small as possible and exhibit a black color.
[0016]
The chargeability of the magnetic toner material particles is described in Japanese Patent Application Laid-Open No. Sho 60-117259, "‥‥ Toner needs to be adjusted to be positively or negatively charged according to the type of photoreceptor. In view of the magnetic particles such as magnetite from the viewpoint, the magnetic particles have the property of being negatively charged.The characteristics of such magnetic particles are the characteristics of the magnetic particles exposed on the toner surface when used in a magnetic toner provided with positive chargeability. It is estimated that the presence of a positively charged portion and a negatively charged portion on the surface of one toner particle due to the presence of the toner particles, and that the charging characteristics differ for each toner particle.In the one-component developing method using magnetic toner, It is assumed that this is one of the causes of markedly abnormal copy image characteristics, and it is desired to make the magnetic particles in the toner positively chargeable. The magnetic particles used for the toner are preferably positively charged, and the magnetic particles used for the negatively chargeable toner are preferably negatively charged. Further, the charge amount of each toner is adjusted to an appropriate range so as to be compatible with the developing device. It is necessary.
[0017]
Regarding the charge amount of the toner, a good image cannot be obtained if the charge amount of the toner is not appropriate. The absolute value of the toner charge amount is 5 to 50 μc. The concentration is preferably 5 to 40 μc / g, more preferably 5 to 30 μc / g, and if it is less than 5 μc / g, the sharpness of the image becomes poor, and the background is stained. In a high-temperature and high-humidity environment, a problem such as a decrease in image density becomes a problem, etc. If it is more than 50 μc / g, electrostatic cohesion increases, image quality decreases, and thin line reproducibility becomes insufficient. In a low-humidity environment, the mirror image with the toner carrier becomes unnecessarily large, which causes a decrease in image density, etc. As described in “‥‥”, the charge amount of the toner is set to 5 to 40 μc / g. It has been demanded.
[0018]
As described in the publication, “‥‥ stabilizes the chargeability of the toner by using a magnetic material whose surface is hydrophobized, and ‥‥”, a magnetic material whose particle surface is hydrophobized. That is, while using zinc ferrite or zinc-manganese ferrite particles whose particle surface has been subjected to hydrophobic treatment, negatively chargeable colloidal silica or positively chargeable colloidal silica is externally added as shown in each example of the publication. The charge amount of the toner is adjusted.
[0019]
The charge amount of the magnetite particles obtained by the above-mentioned wet method is about 0 to -10 μC / g, and as described above, the magnetite particles are dispersed in the resin to realize a magnetic toner capable of high-density development and high resolution. Is difficult to do. Therefore, to increase the content of the magnetic particle powder contained in the resin, or, without using a colorant such as carbon black, high density development, to obtain a magnetic toner capable of high resolution, The magnetic particles are required to have a large charge amount and be black.
[0020]
Conventionally, the magnetization value σ₁₀₀₀Examples of the magnetic particle powder having a small particle size include zinc ferrite particles and zinc-manganese ferrite particles having a spinel-type crystal structure described in JP-A-4-184354. Also, the magnetization value σ₁₀₀₀Is very small and a black pigment powder is described in JP-A-3-2276.
[0021]
[Problems to be solved by the invention]
However, the magnetization value σ₁₀₀₀, And black magnetic iron oxide particles having a large negative charge have not yet been obtained.
[0022]
That is, regarding general-purpose magnetite particle powder, a so-called granular magnetite particle powder having an octahedral or hexahedral shape has a magnetization value σ.₁₀₀₀Is 50-70Am ² / KgAnd the charge amount is about −5 to −10 μC / g, and the spherical magnetite particle powder has a magnetization value σ₁₀₀₀Is 60-75Am ² / KgAnd the charge amount is about 0 to −7 μC / g.
[0023]
Further, the zinc ferrite particles and zinc-manganese ferrite particles described in JP-A-4-184354 described above have a magnetization value σ₁₀₀₀Is 10 to 40Am ² / KgAnd the charge amount is about 0 to −15 μC / g, but as shown in Comparative Example 1 below, the hue is not black but brown, so the blackness is insufficient as a material for magnetic toner. .
[0024]
Further, the black pigment particle powder described in JP-A-3-2276 described above contains a titanium compound in an amount of 15.0 to 50.0 atomic% in terms of Ti with respect to all Fe in the magnetite particles, Magnetization value σ₁₀₀₀0.5 to 5.0Am ² / KgTherefore, it has almost no magnetism and is not suitable as a material particle powder for a magnetic toner or a magnetic carrier. The publication does not disclose or suggest the amount of charge.
[0025]
Then, the present invention provides a₁₀₀₀It is an object of the present invention to obtain black magnetic iron oxide particles having a small particle size, a large negative charge, and excellent blackness.
[0026]
[Means for solving the problem]
The technical problem can be achieved by the present invention as described below.
[0027]
That is, according to the present invention, the magnetization value σ₁₀₀₀Is 20-50Am ² / KgAnd containing a titanium compound in an amount of 0.5 to 10.0 atomic% in terms of Ti with respect to all Fe in the black magnetic iron oxide particles.For a magnetic toner having a charge amount of -10 to -70 µC / gIt is a black magnetic iron oxide particle powder.
[0029]
The configuration of the present invention will be described in more detail as follows.
[0030]
In the present invention, the content of the titanium compound in the black magnetic iron oxide particles is 0.5 to 10.0 atomic% in terms of Ti with respect to all Fe in the black magnetic iron oxide particles. When the content of the titanium compound is less than 0.5 atomic%, the magnetization value σ₁₀₀₀Is 50Am ² / KgHowever, the negative charge amount is small. If it exceeds 10.0 atomic%, the magnetization value σ₁₀₀₀Is 20Am ² / KgTherefore, it is not preferable as a magnetic toner material powder. The preferred content is 0.5-8.0 at%, more preferably 1.0-8.0 at%.
[0031]
Magnetization value σ of black magnetic iron oxide particles in the present invention₁₀₀₀Is 20-50Am ² / KgIt is. Magnetization value σ₁₀₀₀Is 20Am ² / KgIf it is less than 1, the magnetization value becomes too small, so that it is not preferable as a material powder for magnetic toner. 50Am ² / KgWhen the ratio exceeds, the cohesive force due to magnetism increases, and the dispersibility in the resin decreases. Preferably 25 to 50Am ² / KgAnd more preferably 25 to 48Am ² / KgIt is.
[0032]
When the black magnetic iron oxide particles in the present invention are used for a magnetic toner or a magnetic carrier, the charge amount of the particles is −10 to −70 μC / g. When the charge amount is less than −10 μC / g, the charge amount of the magnetic toner when the content of the magnetic iron oxide particles contained in the normal magnetic toner is 30 to 50 wt% is lower than the appropriate range. Is not preferred. If it exceeds -70 μC / g, the charge amount in the case of magnetic toner becomes high, and electrostatic aggregation may occur. Preferably it is -10 to -60 [mu] C / g, more preferably -15 to -60 [mu] C / g.
[0033]
The blackness of the black magnetic iron oxide particles according to the present invention is defined as lightness L.^*A value from 0 to 25,^*The value is -1.0 to +1.0 (L^*Value and a^*Values are CIE1976 (L^*, A^*, B^*) The value displayed in the uniform perceived color space. ). Lightness L^*When the value exceeds 25, the blackness is insufficient. Preferably it is 0-20. a^*When the value is negatively larger than -1.0, greenness is increased and blackness is reduced. If the value exceeds +1.0, the redness becomes strong and the blackness decreases. Preferably it is -1.0 to +0.8.
[0034]
Next, a method for producing the black magnetic iron oxide particles according to the present invention will be described.
[0035]
Examples of the particles to be treated, which are starting materials, include magnetite particle powder and hematite particle powder.
[0036]
First, the magnetite particle powder of the particles to be treated is composed of (1) an aqueous ferrous salt solution and Fe in the aqueous ferrous salt solution.²⁺A suspension containing a ferrous hydroxide colloid having a pH value of 10 or more obtained by reacting an aqueous solution of an alkali hydroxide having an equivalent weight or more with respect to a octahedron was formed by an oxidation reaction in which an oxygen-containing gas was passed through the suspension. A method for obtaining magnetite particle powder (Japanese Patent Publication No. 44-668), (2) an aqueous ferrous salt solution and Fe in the aqueous ferrous salt solution²⁺Oxygen-containing gas is passed through a suspension containing a ferrous hydroxide colloid having a pH value in the range of 6 to 7.5 obtained by reacting an aqueous solution of an alkali hydroxide having an equivalent weight or less with respect to To generate magnetite core particles, and then aerating the suspension containing the magnetite core particles and the ferrous hydroxide colloid with an oxygen-containing gas at a pH value in the range of 8 to 9.5 to thereby form the suspension. A method for obtaining hexahedral magnetite particle powder by performing a growth reaction of magnetite core particles (JP-A-3-201509), and (3) an aqueous ferrous salt solution and Fe in the aqueous ferrous salt solution²⁺Oxygen-containing gas is passed through a suspension containing ferrous hydroxide colloid obtained by reacting 0.80 to 0.99 equivalents of alkali hydroxide with respect to, thereby producing spherical magnetite particles. After the first stage and the completion of the first stage reaction, residual Fe²⁺To obtain a magnetite particle powder having a spherical shape by adding 1.00 equivalent or more of alkali hydroxide to the mixture and oxidizing the mixture at a pH value of 10 or more (Japanese Patent Publication No. Sho 62-51208).
[0037]
Next, the hematite particle powder of the particles to be treated is obtained by, for example, a method of heating and oxidizing each magnetite particle powder obtained by the above methods (1) to (3) in the temperature range of 500 to 900 ° C. in the air. Can be
[0038]
When hematite particles are directly produced from an aqueous solution, for example, JP-B-38-9852, JP-B-60-3012, JP-A-51-8193, JP-A-62-128927. The methods described in the official gazette and Japanese Patent Application Laid-Open No. 62-128930 can be employed.
[0039]
The magnetite particle powder or the hematite particle powder as the particles to be treated may be particles having a granular or spherical shape, and particles having a size of about 0.05 to 0.35 μm can be used. There is a correlation between the size of the particles to be treated and the size of the product particles, and the smaller the particles to be treated, the smaller the product particles, and the larger the particles to be treated, the larger the product particles. Tends to be obtained.
[0040]
The black magnetic iron oxide particle powder according to the present invention is, for example, a magnetite particle powder whose particle surface is coated with a titanium compound, or a reduced powder obtained by reducing a hematite particle powder whose particle surface is coated with a titanium compound. It can be manufactured by a method of baking by heating at a temperature of 650 to 850 ° C. in a non-oxidizing atmosphere and then pulverizing.
[0041]
When magnetite particle powder whose particle surface is coated with a titanium compound is used, the magnetization value σ₁₀₀₀Is preferable because particles having a small particle size are easily obtained.
[0042]
When a hematite particle powder whose particle surface is coated with a titanium compound is used, the coated hematite particle powder is previously reduced at 350 to 500 ° C. in a reducing atmosphere (for example, hydrogen gas) to obtain a particle surface. Are magnetite particles coated with a titanium compound, and are fired and heated at a temperature of 650 to 850 ° C. in a non-oxidizing atmosphere.
[0043]
As the titanium compound, titanyl sulfate (TiOSO₄), Titanium tetrachloride, titanium trichloride and the like.
[0044]
The addition amount of the titanium compound is 0.5 to 10.0 atomic% in terms of Ti with respect to all Fe in the particles to be treated. When the addition amount of the titanium compound is less than 0.5 atomic%, the magnetization value σ₁₀₀₀Is 50Am ² / KgHowever, the charge amount is small. If it exceeds 10.0 atomic%, the magnetization value σ₁₀₀₀Is 20Am ² / KgTherefore, it is not preferable as a material powder for a magnetic toner. The preferred content is 0.5 to 8.0 atomic%, and more preferably 1.0 to 8.0 atomic%.
[0045]
As the non-oxidizing atmosphere, N₂  Gas or the like can be used. If the atmosphere is an oxidizing or reducing atmosphere, the intended black magnetic iron oxide particles cannot be obtained.
[0046]
The heating and firing temperature is in the range of 650 to 850 ° C. If the temperature is lower than 650 ° C., the solid phase reaction between the magnetite particles and the titanium compound does not sufficiently occur, and the desired black magnetic iron oxide particles cannot be obtained. When the temperature exceeds 850 ° C., sintering between the particles of the black magnetic particles is remarkable, and it is difficult to obtain the effect of preventing sintering. Preferably it is 650-750 degreeC.
[0047]
If necessary, the particles to be treated may be coated with a known sintering inhibitor before heating and firing. In this case, it is possible to prevent sintering between particles and particles during heating and firing, and to obtain black magnetic iron oxide particles having excellent dispersibility.
[0048]
Further, as the sintering inhibitor which does not impair various properties of the intended black magnetic iron oxide particles, a compound comprising one or more of elements selected from Al, Si, Zr and P may be used. it can. By using a suitable sintering inhibitor, the chargeability can be improved.
[0049]
The amount of the sintering inhibitor is 0.1 to 15.0 atomic% based on the total Fe in the black magnetic iron oxide particles. In order to obtain a sufficient sintering prevention effect, the content is preferably 0.1 atomic% or more. If it exceeds 15.0 atomic%, a solid phase reaction between the particles to be treated and the titanium compound does not sufficiently occur. It is difficult to obtain the black magnetic iron oxide particles intended for the present invention.
[0050]
Pulverization is usually performed using ball mills, attritors, vibrating mills, and other grinding machines, Simpson mix mullers, multimills, Stotts mills, backflow kneaders, Eirich mills, wet pan mills, melangers, whirlmixes, wheel-type kneaders, etc. And a kneading machine such as a blade-type kneading machine or a grinder.
[0051]
The black magnetic iron oxide particles according to the present invention may be coated with a well-known hydrophobizing agent such as a coupling agent, silicone or a higher fatty acid. The coating amount of the hydrophobizing agent is 0.05 to 2.0% by weight in terms of carbon element with respect to the black magnetic particle powder. If the amount is less than 0.01% by weight, the hydrophobicity is insufficient and the dispersibility is insufficiently improved. If the content exceeds 2.0% by weight, the entire amount of the hydrophobizing agent is not coated on the surface of the black magnetic iron oxide particles, and the hydrophobizing agent alone is present, which is not preferable.
[0052]
Coupling agents include silane coupling agents, titanate coupling agents, aluminate coupling agents, etc., silicones include silicone oils, and higher fatty acids include stearic acid, isostearic acid, palmitic acid, isopalmitic acid, and olein. Acids and the like.
[0053]
In order to improve the chargeability, it is preferable to treat the surface of the magnetic iron oxide particles with a single molecular weight calculated from the coating area per molecule of the hydrophobizing agent. Among the agents, γ-chloropropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane or the like, or silicon oil, etc., when the black magnetic iron oxide particles obtained in the present invention are subjected to hydrophobic treatment, the black This is preferable because the negative charge amount of the magnetic iron oxide particles can be further increased.
[0054]
The hydrophobizing treatment may be either a dry treatment or a wet treatment, but is preferably performed by a dry treatment. In this case, a wheel-type kneader, a grinder, a Henschel mixer, or the like can be used. The addition amount is preferably from 0.25 to 5.0% by weight based on the black magnetic iron oxide particles. If the addition amount is less than 0.25% by weight, hydrophobization is insufficient, and exceeds 5.0% by weight. In this case, the entire hydrophobizing agent is not adsorbed on the particle surface, and the non-adsorbed hydrophobizing agent alone exists.
[0055]
[Action]
The operation of the present invention having the above-described configuration is as follows.
[0056]
The zinc ferrite particles of Comparative Example 1 obtained in the same manner as described in JP-A-4-184354 described above have a magnetization value σ₁₀₀₀Is 31.5Am ² / Kg, The charge amount is −10 μC / g, and L^*The value is 20, but a^*The value is +1.2 and it is brownish.
[0057]
Further, the black pigment particle powder described in the above-mentioned JP-A-3-2276 has a black Fe powder.₂TiO₅And Fe₂O₃-FeTiO₃  Although it is a polycrystalline particle powder having a mixed composition with a solid solution, the magnetization value σ₁₀₀₀Is 0.5 to 5.0Am ² / KgBlack pigment particle powder having almost no magnetism.
[0058]
The present inventors have paid attention to the black pigment particle powder described in JP-A-3-2276, and by improving this pigment particle powder, it is not possible to obtain an excellent black magnetic iron oxide particle powder for magnetic toner. I thought about it and studied it further.
[0059]
First, the charge amount of the black pigment particle powder was measured. As a result, the charge amount was about -15 to -30 μC / g. For this reason, the charge amount was increased by adding a titanium compound to the magnetite particle powder.
[0060]
Next, the content of the titanium compound contained in the magnetite particle powder and the magnetization value σ₁₀₀₀As a result of various investigations on the relationship with, as shown in FIG. 1, when a titanium compound of 0.5 to 10.0 atomic% in terms of Ti was contained with respect to all Fe in the magnetic iron oxide particles, Magnetization value σ₁₀₀₀Is 20-50Am ² / KgIt was found that a magnetic iron oxide particle powder was obtained.
[0061]
Further, as shown in FIG. 2, when a titanium compound exceeding 0.5 atomic% in terms of Ti is contained with respect to all Fe in the magnetic iron oxide particle powder, the charge amount of the magnetic iron oxide particle powder becomes − It was found that magnetic iron oxide particles exceeding 10 μC / g could be obtained.
[0062]
Further, the blackness of the magnetic iron oxide particle powder when the titanium compound is contained in an amount of 0.5 to 10.0 atomic% in terms of Ti with respect to all Fe in the magnetic iron oxide particle powder has a lightness L.^*A value in the range of 0 to 25,^*Since the value was in the range of -1.0 to +1.0, it was found that the blackness was excellent.
[0063]
From the above results, the magnetization value σ of the granular magnetite particle powder₁₀₀₀Is 50-70Am ² / KgThe charge amount was about -5 to -10 μC / g, but the magnetization value σ₁₀₀₀Is 20-45Am ² / KgAnd the charge amount became about -20 to -40 [mu] C / g.
[0064]
Also, the magnetization value σ of the spherical magnetite particle powder₁₀₀₀Is 60-75Am ² / KgHad a charge amount of about 0 to -7 [mu] C / g.₁₀₀₀Is 20-45Am ² / KgAnd the charge amount became about -15 to -35 [mu] C / g.
[0065]
Thus, the magnetization value σ is smaller than that of the magnetite particles which are the particles to be treated.₁₀₀₀30Am ² / KgThus, the negative charge amount could be more than doubled.
[0066]
That is, the black magnetic iron oxide particles according to the present invention have a magnetization value σ₁₀₀₀Is small, the negative charge amount is large, and the blackness is excellent. Therefore, when the magnetic toner is dispersed and mixed in a resin to form a magnetic toner, the content of the magnetic iron oxide particles contained in the magnetic toner can be increased. It is also excellent as a material powder for use.
[0067]
It should be noted that in the above-mentioned JP-A-3-2276, “{magnetite particle powder and hematite particle powder” may be particles of any shape such as granular, spherical, or acicular, and can be used. ” The description and `` マ グ Reduced powder obtained by reducing magnetite particle powder whose particle surface is coated with a titanium compound, a mixed powder of magnetite particle powder and titanium compound or a hematite particle powder whose particle surface is coated with a titanium compound, respectively Is obtained by heating and calcining at a temperature of 700 ° C. or more in a non-oxidizing atmosphere and then pulverizing. As described in “‥‥”, needle-like particles can also be used. Can be obtained by heating and baking the mixed powder at a temperature of 700 ° C. or more in a non-oxidizing atmosphere.
[0068]
However, as shown in Comparative Example 4 below, when the particles to be treated are acicular magnetite particles, the magnetization value σ₁₀₀₀Is 36.0Am ² / KgThe charge amount is −15 μC / g, and a^*Value is +0.8, but L^*Since the value is 27, the lightness L^*Since the value is large and there is a problem with blackness, the black magnetic iron oxide particles intended for the present invention cannot be obtained. The magnetic field of the obtained black magnetic iron oxide particles was79.58 kA / mThe residual magnetization value σr at 25Am ² / KgTherefore, magnetic aggregation is likely to occur and dispersion may be poor, which is not preferable.
[0069]
Further, as shown in Comparative Example 5 below, when the mixed powder of the magnetite particle powder and the titanium compound was heated and fired at a temperature of 700 ° C. in a non-oxidizing atmosphere, the magnetization value σ₁₀₀₀Is 45.0Am ² / Kg, The charge amount is −12 μC / g, and L^*Value is 23, but a^*Since the value is +1.2 and the redness is strong, there is a problem in blackness, so that the black magnetic iron oxide particles intended for the present invention cannot be obtained.
[0070]
Further, when the titanium compound in the predetermined range in the present invention is mixed with the magnetite particles, it is difficult to uniformly mix the titanium compound and the magnetite particles, and the obtained magnetic iron oxide particles are used to form a magnetic toner. In such a case, it is difficult to uniformly disperse the particles, so that it is difficult to reduce the difference in chargeability and magnetic characteristics between the magnetic developer particles.
[0071]
【Example】
Next, the present invention will be described with reference to Examples and Comparative Examples.
[0072]
The shapes of the particles in the following examples and comparative examples were observed with a transmission electron microscope and a scanning electron microscope.
[0073]
The amount of Ti is a value measured by an inductively coupled plasma emission spectrometer (ICAP-575, manufactured by Nippon Jarrell Ash).
[0074]
The magnetic properties of the magnetic particles were measured using a “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.).79.58 kA / m (1 kOe)It is a value measured under.
[0075]
The charge amount was determined by a blow-off measurement method. The measurement was performed using TB-200 (manufactured by Toshiba Chemical Co., Ltd.) as a measuring instrument, using TEFV200 / 300 (manufactured by Powdertech) as a carrier, setting the concentration of magnetic iron oxide particles to 5%, and mixing for 30 minutes.
[0076]
Blackness is L^*(Brightness) and a^*These values are shown as values, and these are obtained by using a light source spectrophotometer MSC-IS-2D (manufactured by Suga Test Instruments Co., Ltd.) to obtain L^*Value and a^*Each color was measured, and the CIE (Commission Internationale de l'Eclairage) 1976 (L^*, A^*, B^*) Values expressed according to the uniform perceived color space.
[0077]
A blackness measurement sample piece was prepared by kneading 0.5 g of black magnetic iron oxide particles containing a titanium compound and 0.5 cc of castor oil with a Hoover-type muller to form a paste, and adding 4.5 g of clear lacquer to the paste. It was obtained by kneading to form a coating and applying it to a cast-coated paper using a 6 mil applicator.
[0078]
<Production of black magnetic iron oxide particles>
Examples 1 to 11, Comparative Examples 1 to 6;
[0079]
Example 1 An average diameter of 0.2 μm and a magnetization value σ₁₀₀₀Is 66.0Am ² / Kg10 kg of spherical magnetite particles having a charge amount of -4 μC / g₄  Is dispersed in an aqueous solution containing 0.065 mol (corresponding to 5.0 atomic% in terms of Ti with respect to the total Fe in the magnetic iron oxide particles), and then NaOH is added to the mixture. The pH value was adjusted to 9.0 by precipitation, and a hydroxide of titanium was deposited on the particle surface. The pH value was adjusted to 7.0 by adding dilute sulfuric acid, followed by filtration, washing with water, and drying. To obtain a spherical black magnetic iron oxide particle powder coated with the hydroxide.
[0080]
10 kg of spherical black magnetic iron oxide particles having the particle surface coated with titanium hydroxide₂After baking by heating at 700 ° C. for 60 minutes under a gas flow, the mixture is treated with a Simpson mix muller (Sandmill MPUV-2: manufactured by Matsumoto Cast Iron Works) at a linear load of 30 kg / cm for 60 minutes to obtain black magnetic iron oxide particles. Obtained.
[0081]
The Ti content of the black magnetic iron oxide particles was 5.2 atomic% based on the total Fe in the particles. Also, the magnetization value σ₁₀₀₀Is 35.0Am ² / Kg, The charge amount is −21 μC / g, and L^*Value is 18, a^*The value was +0.4.
[0082]
Comparative Example 1
40 l of a solution having an NaOH concentration of 183 g / l was charged into a bubble oxidation type reaction tower having an internal volume of 180 l, and then Fe²⁺Neutralization was carried out by adding 36 l of a solution having a concentration of 135 g / l to the NaOH solution with stirring (the residual NaOH was about 4.7 g / l). To this was added 50 l of a solution of zinc hydroxide having a pH of 11.3 (Zn concentration was 40 g / l), and Fe was added.²⁺A reaction solution having a concentration of about 39 g / l was prepared.
[0083]
While maintaining the temperature of the reaction solution at 80 ° C., air was blown at a rate of 10 l / min to perform an oxidation reaction. The reaction was completed in 7 hours. Next, the reaction precipitate was separated by filtration, washed with water, and dried to obtain a zinc ferrite particle powder.
[0084]
10 kg of the above zinc ferrite particle powder was treated with a Simpson mix muller (Sandmill MPUV-2: manufactured by Matsumoto Cast Iron Works) at a linear load of 30 kg / cm for 60 minutes.
[0085]
The obtained zinc ferrite particle powder has a magnetization value σ₁₀₀₀Is 31.5Am ² / Kg, The charge amount is −10 μC / g, and L^*Value is 20, a^*The value was +1.2 and the color was brown.
[0086]
Examples 2 to 11, Comparative Examples 2 to 6
Kind of particles to be treated, kind of titanium compound in coating step with titanium compound, addition amount and pH value at neutralization, presence / absence, kind and amount of treatment with sintering inhibitor, temperature and time in heat treatment step, and crushing treatment The magnetic iron oxide particle powder was obtained in the same manner as in Example 1 except that the line load in was varied.
In Comparative Example 5, the spherical magnetite particle powder and TiOSO₄After dry mixing with the powder, a heat treatment was performed.
[0087]
Tables 1 and 2 show the main production conditions and various characteristics at this time.
[0088]
[Table 1]

[0089]
[Table 2]

[0090]
<Hydrophobic treatment of black magnetic iron oxide particles>
Examples 12 to 15;
[0091]
Example 12
Magnetization value σ obtained in Example 1₁₀₀₀Is 35.0Am ² / Kg, The charge amount is −20 μC / g, and L^*Value is 18, a^*10 kg of black magnetic iron oxide particles having a value of +0.5 were charged into a Simpson mix muller (Sandmill MPUV-2: manufactured by Matsumoto Cast Iron Works), and a silane coupling agent (γ-chloropropyltrimethoxysilane: A-143: manufactured by Nippon Unicar) and treated with a linear load of 30 kg / cm for 60 minutes.
[0092]
The resulting magnetically treated black magnetic iron oxide particles have a magnetization value σ₁₀₀₀Is 34.5Am ² / Kg, The charge amount is −55 μC / g, and L^*Value 17, a^*The value was +0.5.
[0093]
Examples 13 to 15
A black magnetic iron oxide particle powder subjected to hydrophobic treatment was obtained in the same manner as in Example 12, except that the type of the hydrophobic treatment agent was changed.
[0094]
Table 3 shows various characteristics at this time.
[0095]
[Table 3]

[0096]
【The invention's effect】
The black magnetic iron oxide particles according to the present invention have a magnetization value σ, as shown in the above Examples.₁₀₀₀It is a black magnetic iron oxide particle powder that has a small negative charge amount and a large negative charge, and is excellent in blackness. It is suitable as a carrier material particle powder.
[0097]
Further, the black magnetic iron oxide particles according to the present invention can increase the content of the magnetic iron oxide particles contained in the magnetic toner. It is suitable as a material particle powder.
[0098]
Further, since the black magnetic iron oxide particles according to the present invention have excellent blackness, they can be used as black coloring pigment powders for paints, printing inks, rubber and plastics.
[Brief description of the drawings]
FIG. 1 shows the content of the titanium compound and the magnetization value σ of the magnetic iron oxide particles.₁₀₀₀FIG.
FIG. 2 is a graph showing the relationship between the content of a titanium compound in a magnetic iron oxide particle powder and the charge amount.

Claims (1)

The magnetization value σ _{1000 at a} magnetic field of 79.58 kA / m is 20 to 50 Am ² / kg , and 0.5 to 10.0 atomic% of titanium in terms of Ti with respect to all Fe in the black magnetic iron oxide particles. A black magnetic iron oxide particle powder for a magnetic toner containing a compound and having a charge amount of -10 to -70 [mu] C / g .

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