JP3664216B2 - Black magnetic particle powder for black magnetic toner and black magnetic toner using the black magnetic particle powder - Google Patents

Description

【０１４３】
磁性酸化鉄粒子５
磁性酸化鉄粒子１の凝集が解きほぐされた八面体状マグネタイト粒子粉末２０ｋｇと水１５０ｌとを用いて、前記発明の実施の形態と同様にして八面体状マグネタイト粒子粉末を含むスラリーを得た。得られた八面体状マグネタイト粒子粉末を含む再分散スラリーのｐＨ値を４．０とした。次に、該スラリーに水を加えスラリー濃度を９８ｇ／ｌに調整した。このスラリー１５０ｌを加熱して６０℃とし、このスラリー中に１．０ｍｏｌ／ｌの硫酸アルミニウム溶液２７２２ｍｌ（八面体状マグネタイト粒子粉末に対してＡｌ換算で１．０重量％に相当する）を加え、３０分間保持した後、水酸化ナトリウム水溶液を用いてｐＨ値を７．５に調整した。続いてこのスラリー中に３号水ガラス２５４ｇ（八面体状マグネタイト粒子に対してＳｉＯ_２換算で０．５重量％に相当する）を加え３０分間熟成した後、酢酸を用いてｐＨ値を７．５に調整した。この状態で３０分間保持した後、濾過、水洗、乾燥、粉砕して粒子表面がアルミニウムの水酸化物及びケイ素の酸化物により被覆されている八面体状マグネタイト粒子粉末を得た。
【０１４４】
この時の主要製造条件を表２に、得られた八面体状マグネタイト粒子粉末の諸特性を表３に示す。
【０１４５】
【表２】

【０１４６】
【表３】

【０１４７】
磁性酸化鉄粒子６〜８
磁性酸化鉄粒子の種類、表面処理工程における添加物の種類、量を種々変えた以外は磁性酸化鉄粒子５と同様にして表面処理済磁性酸化鉄粒子粉末を得た。
【０１４８】
この時の主要処理条件を表２に、得られた磁性酸化鉄粒子粉末の諸特性を表３に示す。
【０１４９】
実施例１〜８、比較例１〜５
被処理粒子粉末の種類、オルガノシラン化合物による被覆工程におけるアルコキシシランの有無、種類及び添加量、エッジランナー処理条件、カーボンブラック微粒子粉末の付着工程におけるカーボンブラック微粒子粉末の種類及び添加量、エッジランナーによる処理条件を種々変えた以外は、前記発明の実施の形態と同様にして黒色磁性複合粒子粉末を得た。実施例１〜８の各実施例で得られた黒色磁性複合粒子粉末は、電子顕微鏡観察の結果、カーボンブラック微粒子粉末がほとんど認められないことから、カーボンブラック微粒子粉末のほぼ全量が、アルコキシシランから生成するオルガノシラン化合物被覆に付着していることが確認された。
【０１５０】
尚、使用したカーボンブラック微粒子粉末Ａ乃至Ｃの諸特性を表４に示す。
【０１５１】
【表４】

【０１５２】
この時の主要処理条件を表５に、得られた黒色磁性複合粒子粉末の諸特性を表６に示す。
【０１５３】
尚、比較例１は、アルコキシシランを被覆することなく、球状マグネタイト粒子粉末とカーボンブラック微粒子粉末とをエッジランナーで混合攪拌して得られた処理粒子粉末である。この処理粒子粉末の電子顕微鏡写真（×２００００）を図４に示す。図４の電子顕微鏡写真に示される通り、カーボンブラック微粒子粉末が球状マグネタイト粒子粉末の粒子表面に付着しておらず、両粒子粉末がバラバラに混在していることが認められた。
【０１５４】
【表５】

【０１５５】
【表６】

【０１５６】
＜黒色磁性トナーの製造＞
実施例９〜１６及び比較例６〜１４
実施例１〜８の黒色磁性複合粒子粉末、芯粒子１〜４の磁性酸化鉄粒子粉末、比較例１の磁性酸化鉄粒子粉末とカーボンブラック微粒子粉末との混合粉末及び比較例２〜５の黒色磁性粒子粉末を用いて前記発明の実施の形態と同様にして黒色磁性トナーを得た。
【０１５７】
この時の主要製造条件及び諸特性を表７及び表８に示す。
【０１５８】
【表７】

【０１５９】
【表８】

【０１６０】
【発明の効果】
本発明に係る黒色磁性粒子粉末は、流動性及び黒色度が優れているとともに、粒子表面から脱離するカーボンブラック微粒子粉末が少ないことにより、結着剤樹脂中への分散性が優れているので、高画質及び高速の黒色磁性トナー用黒色磁性粒子粉末として好適である。
【０１６１】
また、本発明に係る黒色磁性粒子粉末は、分散性が優れているので、取り扱いやすく作業性に優れており、工業的に好ましいものである。
【０１６２】
そして、上記流動性が優れているとともに黒色度が優れている黒色磁性粒子粉末を用いた黒色磁性トナーもまた流動性が優れているとともに黒色度が優れているので、高画質及び高速の黒色磁性トナーとして好ましいものである。
【０１６３】
また、本発明に係る黒色磁性トナーは、黒色磁性粒子粉末の分散性が優れていることに起因して、磁性トナー粒子表面に露出している黒色磁性粒子粉末の個々が分離、独立して存在しているので、カーボンブラック微粒子粉末が存在することによる体積固有抵抗値の低下がなく、高抵抗乃至絶縁性磁性トナーとして好適である。
【０１６４】
【図面の簡単な説明】
【０１６５】
【図１】 発明の実施の形態で使用した球状マグネタイト粒子粉末の粒子構造を示す電子顕微鏡写真（×２００００）である。
【０１６６】
【図２】 発明の実施の形態で使用したカーボンブラック微粒子粉末の粒子構造を示す電子顕微鏡写真（×２００００）である。
【０１６７】
【図３】 発明の実施の形態で得られた黒色磁性粒子粉末の粒子構造を示す電子顕微鏡写真（×２００００）である。
【０１６８】
【図４】 比較のために示した球状マグネタイト粒子粉末とカーボンブラック微粒子粉末との混合粉末の粒子構造を示す電子顕微鏡写真（×２００００）である。[0001]
[Industrial application fields]
The present invention provides black magnetic particles for black magnetic toners that are excellent in fluidity and blackness, and are excellent in dispersibility in a binder resin due to a small amount of carbon black fine particle powder that is detached from the particle surface. An object of the present invention is to provide a powder and a black magnetic toner using the black magnetic particle powder.
[0002]
[Prior art]
Conventionally, as one of the electrostatic latent image developing methods, a so-called one-component magnetism is used in which a composite particle in which magnetic particle powder such as magnetite particle powder is mixed and dispersed in a resin without using a carrier is used as a developer. Developing methods using toner are widely known and widely used.
[0003]
One-component magnetic toners are roughly classified into a CPC system using a low-resistance magnetic toner and a PPC system using an insulating or high-resistance magnetic toner.
[0004]
The former has conductivity and is developed by charging the magnetic toner by electrostatic induction due to the latent image charge. However, the electrostatic toner loses the charge of the magnetic toner during the period from development to transfer. It was not suitable for PPC of the system. To compensate for this drawback, the latter volume resistivity value is 10¹⁴A magnetic toner having an insulating or high resistance of Ω · cm or more has been developed.
[0005]
In this insulating or high-resistance magnetic toner, it is known that magnetic particles exposed from the surface of the magnetic toner affect development characteristics.
[0006]
Recently, with the improvement in image quality and speed of copying machines such as image density and gradation, there has been a strong demand for improving the properties of insulating or high-resistance magnetic toners, especially developer, as a developer. ing.
[0007]
Regarding this fact, Japanese Patent Application Laid-Open No. 53-94932 “Such high-resistance magnetic toner has a high resistance, so it has poor fluidity and easily develops unevenness. That is, for PPC. The high-resistance magnetic toner can maintain the charge necessary for transfer, but in the toner bottle or on the surface of the magnetic roll, it is not necessary to be charged other than the transfer process. It is easy to cause charge aggregation due to slight electrification caused by electrets, etc., which leads to a decrease in fluidity. ”,“ Another object of the present invention is to improve the flowability of PPC. By providing a resistance magnetic toner, it is possible to obtain a high-quality indirect copy with no development unevenness, and hence excellent resolution and gradation.
[0008]
Further, the above-described improvement in fluidity of magnetic toner is strongly demanded as the magnetic particle size of insulating or high-resistance magnetic toner is recently reduced.
This fact requires that the quality of image quality be improved as printers such as ICP are widely deployed on page 121 of “General Materials for Toner Material Development and Practical Use” published by Nippon Kagaku Information Co., Ltd. The appearance of high-resolution and high-definition printers is particularly required, and Table 1 shows the relationship between the resolution when various toners are used, but wet toner with a small diameter can produce high resolution. In order to improve resolution, it is necessary to reduce the toner diameter .... As a report using small diameter toner, the use of 8.5 μ to 11 μ toner improves the background fogging and further reduces the consumption. In addition, when a polyester toner of 6 to 10 μm is employed, there are proposals for improving the image quality, stabilizing the charging property, and improving the developer life.
However, many problems must be solved when using small diameter toner. Manufacturability, sharpness of particle size distribution, fluidity improvement, etc. exist. Is as described.
[0009]
Further, currently used black magnetic toner is required to have a high degree of blackness and darkness in a copied line image and solid area image.
This fact is based on “Toner Material Development / Practical Application Technical Data” on page 272 “High image density is a characteristic of powder development, but it greatly affects image characteristics along with the fog density described later. It is as described.
[0010]
The properties of the magnetic toner and the properties of the magnetic particle powder mixed and dispersed in the magnetic toner are closely related.
[0011]
That is, since the fluidity of the magnetic toner greatly depends on the surface state of the magnetic particles exposed on the surface of the magnetic toner, it is strongly required that the fluidity of the magnetic particles themselves is excellent.
[0012]
Similarly, the degree of blackness and darkness of the magnetic toner also greatly depends on the degree of blackness and darkness of the magnetic particle powder, which is a black pigment contained in the magnetic toner.
[0013]
As black pigments, magnetite particle powders that are practical in terms of magnetic properties such as saturation magnetization and coercive force, price, and color tone are widely used. In addition to the magnetite particle powder, carbon black fine particle powder and the like may be further added. However, when a large amount of carbon black fine particle powder is used, the volume resistivity decreases, and it cannot be used as an insulating or high resistance magnetic toner.
[0014]
Further, since the addition of a large amount of carbon black fine particle powder becomes a factor that inhibits the dispersibility of the magnetite particle powder in the binder resin, the amount of carbon black fine particle powder added to the binder resin is acceptable. There is a strong demand for as little as possible.
[0015]
Various attempts have been made to improve the fluidity of the magnetite particle powder mixed and dispersed in the black magnetic toner in order to improve the fluidity of the black magnetic toner. For example, (1) the shape of the magnetite particle powder is changed. There are a spherical method (Japanese Patent Laid-Open No. 59-64852, etc.), and (2) a method in which a silicon compound is exposed on the surface of magnetite particle powder (Japanese Patent Publication No. 8-25747).
[0016]
[Problems to be solved by the invention]
The black magnetic particle powder for black magnetic toner, which is excellent in fluidity and blackness and has excellent dispersibility in the binder resin, is currently the most demanded, and has such characteristics. Black magnetic particle powder has not been obtained yet.
[0017]
That is, the known magnetite particle powders having a spherical shape are superior in fluidity compared to cubic magnetite particle powders, octahedral magnetite particle powders, etc., but are still not sufficient. In addition, the blackness is low.
[0018]
Similarly, the magnetite particle powder having a silicon compound exposed on the surface of the above-mentioned known particles is also not sufficiently fluid and has a low blackness.
[0019]
When the carbon black fine particle powder is added to improve the blackness of these known magnetite particle powders, the dispersibility of the magnetite particle powder in the binder resin is inhibited as described above.
[0020]
Therefore, the present invention has a technical problem to obtain black magnetic particle powder for black magnetic toner having excellent fluidity and blackness, and excellent dispersibility in a binder resin.
[0021]
[Means for solving the problems]
The technical problem can be achieved by the present invention as follows.
[0022]
That is, according to the present invention, the surface of the magnetic iron oxide particles having an average particle size of 0.055 to 0.95 μm is coated with an organosilane compound generated from alkoxysilane, and the organosilane compound coating has an average particle size of 0. A black magnetic composite particle powder having a carbon black fine particle powder of 0.002 to 0.05 μm adhered thereto, wherein the total amount of the carbon black fine particle powder is 1 to 25 parts by weight with respect to 100 parts by weight of the magnetic iron oxide particle powder. Black magnetic particle powder for black magnetic toner, characterized in that there is an aluminum hydroxide, aluminum oxide, silicon as a lower layer on the particle surface of magnetic iron oxide particle powder having an average particle diameter of 0.055 to 0.95 μm One or two or more types selected from hydroxides and silicon oxides are coated and formed as an upper layer from alkoxysilane. A black magnetic composite particle powder coated with a nosilane compound and having a carbon black fine particle powder having an average particle size of 0.002 to 0.05 μm attached to the organosilane compound coating, and the total amount of the carbon black fine particle powder 1 to 25 parts by weight with respect to 100 parts by weight of the magnetic iron oxide particle powder, and a black magnetic toner using any one of the black magnetic particle powders.
[0023]
The configuration of the present invention will be described in more detail as follows.
[0024]
First, the black magnetic particle powder according to the present invention will be described.
[0025]
In the black magnetic particle powder according to the present invention, the surface of the magnetic iron oxide particle powder having an average major axis diameter of 0.055 to 0.95 μm as the core particle is coated with an organosilane compound generated from alkoxysilane, It consists of black magnetic composite particles in which carbon black fine particles having an average particle size of 0.002 to 0.05 μm are attached to the organosilane compound coating.
[0026]
Magnetic iron oxide particle powder is magnetite particle powder (FeO _x・ Fe₂O₃  0 <X ≦ 1), maghemite particle powder (γ-Fe₂O₃) And mixed particle powders thereof. Considering the blackness of the resulting black magnetic composite particle powder, magnetite particle powder is preferred.
[0027]
The particle shape of the magnetic iron oxide particle powder is isotropic particles such as spherical, granular, hexahedral, octahedral, and polyhedral shapes and an axial ratio (average major axis diameter / average minor axis diameter) (hereinafter referred to as “axis ratio”). ) May be any of two or more anisotropic particles such as needles, spindles, and rice grains. Considering the fluidity of the resulting black magnetic composite particle powder, the magnetic iron oxide particles are preferably isotropic particles, more preferably spherical.
[0028]
In the case of isotropic particles, the magnetic iron oxide particles have an average particle size of 0.055 to 0.95 μm, preferably 0.065 to 0.75 μm, more preferably 0.065 to 0.45 μm. The ratio of the longest diameter to the shortest diameter is 1 or more and less than 2, preferably 1 to 1.8. In the case of anisotropic particles, the average major axis diameter is 0.055 to 0.95 μm, preferably 0.00. 065 to 0.75 μm, more preferably 0.065 to 0.45 μm, and the axial ratio is 2 to 20, preferably 2 to 15 and more preferably 2 to 10.
[0029]
When the average particle diameter exceeds 0.95 μm, the resulting black magnetic composite particle powder becomes coarse particles and the coloring power is reduced. If the particle size is less than 0.055 μm, aggregation is likely to occur due to an increase in intermolecular force due to particle miniaturization. Therefore, uniform coating treatment with alkoxysilane on the particle surface of the magnetic iron oxide particle powder and carbon black fine particle powder A uniform adhesion process becomes difficult.
[0030]
When the axial ratio of anisotropic particles exceeds 20, entanglement of particles increases, and uniform coating treatment with alkoxysilane and uniform adhesion treatment with carbon black fine particle powder on the surface of magnetic iron oxide particle powder. It becomes difficult.
[0031]
The geometric standard deviation value of the particle diameter of the magnetic iron oxide particle powder (major axis diameter in the case of anisotropic particles) is preferably 2.0 or less, more preferably 1.8 or less, still more preferably 1.6 or less. It is. When the geometric standard deviation value exceeds 2.0, the coarse particles present inhibit the uniform dispersion of the binder resin in the binder resin. Processing and uniform adhesion treatment with carbon black fine particle powder become difficult. The lower limit value of the geometric standard deviation value is 1.01, and those less than 1.01 are difficult to obtain industrially.
[0032]
The magnetic iron oxide particle powder has a BET specific surface area of 0.5 m.²/ G or more. BET specific surface area is 0.5m²When the particle size is less than / g, the magnetic iron oxide particle powder is coarse or particles are sintered between the particles, and the resulting black magnetic composite particle powder is coarse and has a coloring power. descend. Considering the coloring power of the black magnetic composite particle powder, the BET specific surface area value is preferably 1.0 m.²/ G or more, more preferably 3.0 m²/ G or more. Considering the uniform coating treatment with the alkoxysilane and the uniform adhesion treatment with the carbon black fine particle powder on the surface of the magnetic iron oxide particle powder, the upper limit is 70 m.²/ G, preferably 50 m²/ G or less, more preferably 20 m²/ G or less.
[0033]
As for the fluidity of the magnetic iron oxide particle powder, the fluidity index is about 25 to 43. Among various types of magnetic iron oxide particle powders, spherical particle powders are excellent in fluidity, but still have a fluidity index of about 30 to 43.
[0034]
The blackness of magnetic iron oxide particles is usually L in the case of magnetite particles.^*The lower limit of the value exceeds 18.0, and the upper limit is 25.0, preferably 24.0. In the case of maghemite particle powder, usually L^*The lower limit of the value exceeds 18.0, and the upper limit is 34, preferably 32. L^*When the value exceeds the above upper limit, the brightness becomes high and black magnetic composite particle powder having sufficient blackness cannot be obtained.
[0035]
The magnetic properties of the magnetic iron oxide particles are such that the coercive force value is about 10 to 350 Oe, preferably about 20 to 330 Oe, and the saturation magnetization value in a magnetic field of 10 KOe is about 50 to 91 emu / g, preferably 60 to 90 emu. The residual magnetization value in a magnetic field of 10 KOe is about 1 to 35 emu / g, preferably about 3 to 30 emu / g.
[0036]
The particle shape and particle size of the black magnetic particle powder according to the present invention largely depend on the particle shape and particle size of the magnetic iron oxide particle powder as the core particle powder, and have a particle form similar to the magnetic iron oxide particle. And has a slightly larger particle size than the magnetic iron oxide particles.
[0037]
That is, the black magnetic particle powder according to the present invention has an average particle diameter of 0.06 to 1.0 μm, preferably 0.07 to 1.0 mm when the isotropic magnetic iron oxide particle powder is used as the core particle powder. An anisotropic magnetic iron oxide particle powder having a length of 0.8 μm, more preferably 0.07 to 0.5 μm, and a ratio of the longest diameter to the shortest diameter of 1 or more and less than 2, preferably 1 to 1.8 Is a core particle powder, the average major axis diameter is 0.06 to 1.0 μm, preferably 0.07 to 0.8 μm, more preferably 0.07 to 0.5 μm, and the axial ratio is 2. -20, preferably 2-15, more preferably 2-10. .
[0038]
When the average particle diameter exceeds 1.0 μm, the black magnetic particle powder becomes coarse particles and the coloring power is reduced. When the particle size is less than 0.06 μm, aggregation is likely to occur due to an increase in intermolecular force due to finer particles, so that the dispersibility in the binder resin during the production of the magnetic toner is lowered.
[0039]
The upper limit of the axial ratio of anisotropic particles is preferably 20, more preferably 18, and still more preferably 15. When it exceeds 20, the fineness of the particles in the binder resin increases and the dispersibility tends to decrease.
[0040]
The geometric standard deviation value of the black magnetic particle powder is preferably 2.0 or less, and the lower limit is 1.01, more preferably in the range of 1.01 to 1.8, and still more preferably 1.01. ~ 1.6. When the geometric standard deviation value exceeds 2.0, the coloring power of the black magnetic particle powder tends to decrease due to the existing coarse particles. Those having a geometric standard deviation value of less than 1.01 are difficult to obtain industrially.
[0041]
The BET specific surface area value of the black magnetic particle powder is 1 to 200 m.²/ G, preferably 2 to 150 m²/ G, more preferably 2.5 to 100 m²/ G. BET specific surface area value is 1m²If it is less than / g, the particles are coarse or the particles are sintered between the particles and the coloring power is reduced. BET specific surface area value is 200m²When the amount exceeds / g, aggregation tends to occur due to an increase in intermolecular force due to finer particles, so that the dispersibility in the binder resin during the production of the magnetic toner is lowered.
[0042]
The fluidity of the black magnetic particle powder is preferably in the range of a fluidity index of 44 to 80, more preferably 45 to 80, and even more preferably 46 to 80. When the fluidity index is less than 44, it is difficult to say that the fluidity is sufficient, and it is difficult to improve the fluidity of the obtained magnetic toner. In addition, problems such as hopper clogging are likely to occur in the manufacturing process, making handling difficult.
[0043]
The blackness of the black magnetic particle powder has an upper limit of L when magnetite particle powder is used as the core particle powder.^*The value is 20.0, preferably 19.0, more preferably 18.0. When maghemite particle powder is used as the core particle powder, the upper limit is L^*The value is 20.0, preferably 19.5, more preferably 19.0. L^*When the value exceeds 20.0, the brightness is high and the blackness is not sufficient. The lower limit of blackness is L^*The value is 15.
[0044]
The dispersibility of the black magnetic particle powder in the binder resin is preferably 4 or 5, more preferably 5, based on the dispersibility evaluation method described below.
[0045]
The desorption rate of the carbon black fine particle powder of the black magnetic particle powder is preferably 20% or less, more preferably 10% or less. When the desorption rate of the carbon black fine particle powder exceeds 20%, the dispersed carbon black fine particle powder may inhibit uniform dispersion in the binder resin during the production of the magnetic toner.
[0046]
The magnetic properties of the black magnetic particle powder can be controlled by selecting the type and particle shape of the magnetic iron oxide particles, and the coercive force value is 10 to 350 Oe, similar to the magnetic particle powder normally used for magnetic toner. The saturation magnetization value in a magnetic field of 10 KOe is about 50 to 91 emu / g, preferably about 60 to 90 emu / g, and the residual magnetization value in a magnetic field of 10 KOe is about 20 to 330 Oe. About 1 to 35 emu / g, preferably about 3 to 30 emu / g can be used.
[0047]
The organosilane compound in the black magnetic particle powder isChemical 3It produces | generates through the drying thru | or a heating process from the alkoxysilane represented by these.
<Chemical Formula 3>R_aSiX_4-a
R: -C₆H₅,-(CH₃)₂CHCH₂, -N-C_mH_{2m + 1}
X: -OCH₃, -OC₂H₅
m: an integer from 1 to 18
a: integer from 0 to 3
[0048]
Specific examples of the alkoxysilane include methyltriethoxysilane, dimethyldiethoxysilane, tetraethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, tetramethoxysilane, and phenyltrimethoxy. Examples include silane, diphenyldimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane.
[0049]
In view of the adhesion effect and desorption rate of the carbon black fine particle powder, an organosilane compound formed from methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, isobutyltrimethoxysilane, and phenyltriethoxysilane is preferable, and methyltriethoxysilane An organosilane compound produced from methyltrimethoxysilane is most preferred.
[0050]
The coating amount of the organosilane compound is preferably 0.02 to 5.0% by weight in terms of Si with respect to the organosilane compound-coated magnetic iron oxide particle powder. More preferably, it is 0.03-2.0 weight%, More preferably, it is 0.05-1.5 weight%.
[0051]
When it is less than 0.02% by weight, it is difficult to sufficiently adhere the carbon black fine particle powder to the magnetic iron oxide particles to such an extent that the flowability and blackness of the obtained black magnetic particle powder can be improved.
[0052]
When the amount exceeds 5.0% by weight, the carbon black fine particle powder can be sufficiently adhered to the magnetic iron oxide particles, but the flowability and blackness of the obtained black magnetic composite particle powder are saturated, so the coating is more than necessary. There is no meaning to do.
[0053]
As the carbon black fine particle powder in the black magnetic particle powder, commercially available furnace black, channel black or the like can be used, and specifically, MA100, MA7, # 1000, # 2400B, # 30, MA8, MA11, # 50. , # 52, # 45, # 2200B, MA600, etc. (trade name: Mitsubishi Chemical Co., Ltd.) SEAST 9H, SEAST 7H, SEAST 6, SEAST 3H, SEAST 300, SEAST FM, etc. (trade name, Tokai Carbon Co., Ltd.) (Made)) can be used. Considering the affinity with the organosilane compound, MA100, MA7, # 1000, # 2400B, and # 30 are preferable.
[0054]
The average particle size of the carbon black fine particle powder is about 0.002 to 0.05 μm, more preferably about 0.002 to 0.035 μm.
[0055]
If it is less than 0.002 μm, the carbon black fine particle powder becomes too fine, making it difficult to handle.
[0056]
If it exceeds 0.05 μm, the particle size of the carbon black fine particle powder becomes too large relative to the particle size of the magnetic iron oxide particle powder, so that the adhesion strength to the organosilane compound coating becomes insufficient, and the carbon black fine particle powder As a result, the dispersibility of the toner in the binder resin may be reduced during the production of the magnetic toner.
[0057]
The ratio between the average particle size of the magnetic iron oxide particle powder and the average particle size of the carbon black fine particle powder is preferably 2 or more. If it is less than 2, the particle size of the carbon black fine particle powder becomes too large relative to the particle size of the magnetic iron oxide particle powder, resulting in insufficient adhesion strength to the organosilane compound coating, and the desorption rate of the carbon black fine particle powder. As a result, the dispersibility of the binder resin in the production of the magnetic toner may decrease.
[0058]
The adhesion amount of the carbon black fine particle powder is 1 to 25 parts by weight with respect to 100 parts by weight of the magnetic iron oxide particle powder.
[0059]
When the amount is less than 1 part by weight, the adhesion amount of the carbon black fine particle powder is insufficient, and it becomes difficult to obtain black magnetic composite particle powder having sufficient fluidity and blackness.
[0060]
When the amount exceeds 25 parts by weight, the resulting black magnetic composite particle powder has sufficient fluidity and blackness, but the carbon black fine particle powder tends to be detached because the carbon black fine particle powder has a large amount of adhesion. As a result, the dispersibility of the binder resin in the production of the magnetic toner may be reduced.
[0061]
If necessary, the black magnetic particle powder has one or two kinds of magnetic iron oxide particle powder selected from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide in advance. It may be coated as described above (hereinafter referred to as “aluminum hydroxide coating”), and compared with the case where it is not coated with aluminum hydroxide or the like, it is dispersed in the binder resin during magnetic toner production. More improved.
[0062]
The coating amount of aluminum hydroxide or the like is Al equivalent to the magnetic iron oxide particle powder coated with aluminum hydroxide or the like, SiO₂Conversion or Al conversion amount and SiO₂The total amount with the converted amount is preferably 0.01 to 50% by weight.
[0063]
If it is less than 0.01% by weight, the effect of improving the dispersibility in the binder resin during the production of the magnetic toner cannot be obtained.
[0064]
If it exceeds 50% by weight, the effect of improving the dispersibility in the binder resin during the production of the magnetic toner can be obtained, but there is no point in covering more than necessary.
[0065]
In the black magnetic particle powder according to the present invention, the surface of the magnetic iron oxide particle powder is coated with an aluminum hydroxide or the like, the particle surface of the magnetic iron oxide particle powder is not coated with an aluminum hydroxide or the like About the same particle size, geometric standard deviation value, BET specific surface area value, fluidity, blackness L as in the case of the black magnetic particle powder according to the present invention^*Value, desorption rate of carbon black fine particle powder and magnetic properties.
[0066]
The black magnetic particle powder according to the present invention can be obtained by the following production method.
[0067]
First, a method for producing magnetic iron oxide particles in the present invention will be described.
[0068]
The isotropic magnetite particle powder consists of (1) ferrous salt aqueous solution and Fe in the ferrous salt aqueous solution.²⁺A method for producing octahedral magnetite particle powder by aeration of oxygen-containing gas into a suspension containing ferrous hydroxide colloid having a pH value of 10 or more obtained by reacting with an alkaline aqueous solution having an equivalent or more equivalent to ( Japanese Patent Publication No. 44-668). (2) Ferrous salt aqueous solution and Fe in the ferrous salt aqueous solution²⁺Magnetite core particles by aerating an oxygen-containing gas to a suspension containing ferrous hydroxide colloid having a pH value in the range of 6.0 to 7.5 obtained by reacting with an alkaline aqueous solution having an equivalent amount or less with respect to A hexahedral magnetite particle powder is obtained by aerating an oxygen-containing gas in the pH value range of 8.0 to 9.5 to the ferrous salt reaction aqueous solution containing the magnetite core particles and the ferrous hydroxide colloid. A generating method (Japanese Patent Laid-Open No. 3-201509). (3) Ferrous salt aqueous solution and Fe in the ferrous salt aqueous solution²⁺Magnetite core particles by aerating an oxygen-containing gas to a suspension containing ferrous hydroxide colloid having a pH value in the range of 6.0 to 7.5 obtained by reacting with an alkaline aqueous solution having an equivalent amount or less with respect to To produce residual Fe²⁺It can be obtained by a method (Japanese Examined Patent Publication No. Sho 62-51208) of adding spherical hydroxide of an equivalent amount or more and heating and oxidizing at a pH value of 10 or more.
[0069]
The isotropic maghemite particle powder can be obtained by heating the isotropic magnetite particle powder in the range of 300 to 600 ° C. in the air.
[0070]
Anisotropic magnetite particle powder is a ferrous hydroxide colloid obtained by reacting an aqueous ferrous salt solution with alkali hydroxide, alkali carbonate or alkali hydroxide / alkaline carbonate, iron carbonate, and iron-containing precipitate. While controlling the pH value and temperature of the suspension containing the above, a needle-like, spindle-like or rice granular goethite particle powder is produced by aeration of an oxygen-containing gas through the suspension to oxidize the goethite The particle powder can be obtained by filtration, washing with water, and drying, followed by heat reduction at 300 to 800 ° C. in a reducing gas.
[0071]
The anisotropic maghemite particle powder can be obtained by heating and oxidizing the anisotropic magnetite particle powder in an oxidizing gas in the range of 300 to 600 ° C.
[0072]
The magnetic iron oxide particle powder is coated with alkoxysilane by mechanically mixing and stirring the magnetic iron oxide particle powder and the alkoxysilane solution, or spraying the alkoxysilane solution on the magnetic iron oxide particle powder. It is only necessary to mix and stir. Almost all of the added alkoxysilane is coated on the surface of the magnetic iron oxide particles.
[0073]
In order to coat the alkoxysilane uniformly on the surface of the magnetic iron oxide particle powder, it is preferable that the agglomeration of the magnetic iron oxide particle powder is previously unraveled using a pulverizer. As an apparatus for mixing and stirring, an edge runner, a Henschel mixer, or the like can be used.
[0074]
The conditions during mixing and stirring may be adjusted as appropriate so that the surface ratio of the magnetic iron oxide particles is covered with alkoxysilane as uniformly as possible, such as the amount ratio, linear load, stirring speed, and mixing stirring time. 20 minutes or more is preferable.
[0075]
The amount of alkoxysilane added is preferably 0.15 to 45 parts by weight with respect to 100 parts by weight of magnetic iron oxide particle powder. When the amount is less than 0.15 parts by weight, it is difficult to sufficiently adhere the carbon black fine particle powder to such an extent that the blackness and fluidity can be improved. When it exceeds 45 parts by weight, the carbon black fine particle powder can be sufficiently adhered, but there is no meaning to add more than necessary.
[0076]
After coating the surface of the magnetic iron oxide particle powder with alkoxysilane, the carbon black fine particle powder is added, followed by mixing and stirring to adhere the carbon black fine particle powder to the alkoxysilane coating, followed by drying or heat treatment.
[0077]
The carbon black fine particle powder is preferably added over a period of about 5 to 60 minutes while taking a small amount of time.
[0078]
Conditions for mixing and stirring may be appropriately adjusted such that the amount ratio, linear load, stirring speed, mixing and stirring time, etc. so that the carbon black fine particle powder adheres uniformly, and the treatment time is preferably 20 minutes or more.
[0079]
The addition amount of the carbon black fine particle powder is 1 to 25 parts by weight with respect to 100 parts by weight of the magnetic iron oxide particle powder. When the amount is less than 1 part by weight, the amount of carbon black fine particle powder attached is insufficient, and black magnetic composite particle powder having sufficient blackness and fluidity cannot be obtained. When the amount exceeds 25 parts by weight, sufficient blackness and fluidity can be obtained, but the amount of carbon black fine particle powder increases, so that the carbon black fine particle powder is easily detached from the particle surface. Dispersibility in the binder resin during production is reduced.
[0080]
The heating temperature in the drying or heating step is usually preferably 40 to 200 ° C, more preferably 60 to 150 ° C, and the treatment time is preferably 10 minutes to 12 hours, more preferably 30 minutes to 3 hours. Alkoxysilane becomes an organosilane compound by this drying or heating process.
[0081]
The magnetic iron oxide particle powder may be one kind selected from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide in advance of mixing and stirring with the alkoxysilane solution, if necessary. You may coat | cover with 2 or more types.
[0082]
The coating with aluminum hydroxide or the like is performed by adding an aluminum compound, a silicon compound or both of the compounds to an aqueous suspension obtained by dispersing magnetic iron oxide particle powder, and mixing and stirring, or as necessary. , By adjusting the pH value after mixing and stirring, the particle surface of the magnetic iron oxide particle powder is selected from the group consisting of aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide, or Cover with two or more, then filter, wash, dry and grind. If necessary, a deaeration / consolidation process may be further performed.
[0083]
As the aluminum compound, aluminum salts such as aluminum acetate, aluminum sulfate, aluminum chloride, and aluminum nitrate, alkali aluminates such as sodium aluminate, alumina sol, and the like can be used.
[0084]
The addition amount of the aluminum compound is 0.01 to 50% by weight in terms of Al with respect to the magnetic iron oxide particle powder. When the amount is less than 0.01% by weight, it is difficult to coat the particle surface with a sufficient amount of aluminum hydroxide and the like. I can't get it. If it exceeds 50% by weight, the coating effect is saturated, so there is no point in adding more than necessary.
[0085]
As the silicon compound, No. 3 water glass, sodium orthosilicate, sodium metasilicate, colloidal silica and the like can be used.
[0086]
The amount of silicon compound added is SiO to the magnetic iron oxide particle powder.₂It is 0.01 to 50% by weight in terms of conversion. If it is less than 0.01% by weight, it is difficult to coat a sufficient amount of silicon oxide etc. on the particle surface, and the effect of improving the dispersibility in the binder resin during magnetic toner production is obtained. I can't. If it exceeds 50% by weight, the coating effect is saturated, so there is no point in adding more than necessary.
[0087]
When the aluminum compound and the silicon compound are used in combination, the amount added is equivalent to the amount in terms of Al and SiO2 with respect to the magnetic iron oxide particles.₂The total amount with the converted amount is preferably 0.01 to 50% by weight.
[0088]
Next, the black magnetic toner according to the present invention will be described.
[0089]
The black magnetic toner according to the present invention comprises the black magnetic particle powder for a black magnetic toner and a binder resin, and contains a release agent, a colorant, a charge control agent, other additives and the like as necessary. Also good.
[0090]
The black magnetic toner according to the present invention has an average particle diameter of 3 to 15 μm, preferably 5 to 12 μm.
[0091]
The ratio of the binder resin to the black magnetic particle powder is 50 to 900 parts by weight, preferably 50 to 400 parts by weight, based on 100 parts by weight of the black magnetic particle powder.
[0092]
As the binder resin, a vinyl polymer obtained by polymerizing or copolymerizing vinyl monomers such as styrene, alkyl acrylate ester and alkyl methacrylate ester can be used. Examples of the styrene monomer include styrene and substituted products thereof. Examples of the alkyl acrylate monomer include acrylic acid, methyl acrylate, ethyl acrylate, and butyl acrylate.
[0093]
The copolymer preferably contains 50 to 95% by weight of a styrene component.
[0094]
As the binder resin, a polyester resin, an epoxy resin, a polyurethane resin, or the like can be used in combination with the vinyl polymer as necessary.
[0095]
The black magnetic toner according to the present invention has a fluidity index of 70 to 100, preferably 71 to 100, more preferably 72 to 100. If it is less than 70, the fluidity is not sufficient.
[0096]
The blackness of the black magnetic toner according to the present invention is L^*The value is 20 or less, preferably 19.8 or less, more preferably 19.5 or less. When it exceeds 20, the brightness becomes high and the blackness is not sufficient. The lower limit is L^*The value is about 15.
[0097]
The volume resistivity of the black magnetic toner is 1.0 × 10¹³Ω · cm or more, preferably 3.0 × 10¹³Ω · cm or more, more preferably 5.0 × 10¹³Ω · cm or more. 1.0 × 10¹³If it is less than Ω · cm, the charge amount is likely to change depending on the toner usage environment, and the characteristics tend to be unstable. The upper limit is 10¹⁵It is about Ω · cm.
[0098]
The magnetic properties of the black magnetic toner are generally 10 to 350 Oe, preferably 20 to 330 Oe, and have a saturation magnetization value in a magnetic field of 10 KOe, similar to the magnetic toner used for electrostatic latent image development. 10 to 85 emu / g, preferably 20 to 80 emu / g, residual magnetization value is 1 to 20 emu / g, preferably 2 to 15 emu / g, and saturation magnetization value in a magnetic field of 1 KOe is 7.5 to 65 emu. / G, preferably 10 to 60 emu / g, and the residual magnetization value is 0.5 to 15 emu / g, preferably 1.0 to 13 emu / g.
[0099]
The black magnetic toner according to the present invention can be produced by a known method by mixing, kneading and pulverizing a predetermined amount of binder resin and a predetermined amount of black magnetic particle powder. Specifically, after sufficiently mixing the black magnetic particle powder and the binder resin, if necessary, a mixture further added with a release agent, a colorant, a charge control agent, other additives, etc., using a mixer, Disperse black magnetic particle powder and the like in the binder resin with a heating kneader, then solidify by cooling to obtain a resin kneaded product, and pulverize and classify the resin kneaded product to obtain a black magnetic particle having a desired particle size. Toner can be obtained.
[0100]
As the mixer, a mixer such as a Henschel mixer or a ball mill can be used. As the heating kneader, a roll mill, a kneader, a biaxial 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 the classification can also be performed by known air classification or the like as described in Japanese Patent No. 2683142.
[0101]
As another method for obtaining the black magnetic toner, there is a suspension polymerization method or an emulsion polymerization method. In the suspension polymerization method, a polymerizable monomer and black magnetic particle powder are dissolved or dispersed in a mixture containing a colorant, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives as necessary. The resulting monomer composition can be added to an aqueous phase containing a suspension stabilizer while stirring, granulated, and polymerized to form black magnetic toner particles having a desired particle size.
[0102]
In the emulsion polymerization method, the monomer and the black magnetic particle powder have a desired particle size by adding an emulsifier to the process of carrying out polymerization by further dispersing a colorant, a polymerization initiator, etc. in water if necessary. Black magnetic toner particles can be formed.
[0103]
DETAILED DESCRIPTION OF THE INVENTION
A typical embodiment of the present invention is as follows.
[0104]
The average particle diameter or average major axis diameter and average minor axis diameter of magnetite particle powder, maghemite particle powder, black magnetic particle powder, and carbon black fine particle powder are four times as long as the electron micrograph (× 20000) in the vertical and horizontal directions, respectively. The fixed direction diameter was measured for each of about 350 particles shown in the enlarged photograph, and the average value was shown.
[0105]
The axial ratio is shown as the ratio of the average major axis diameter to the average minor axis diameter.
[0106]
The geometric standard deviation value of the particle was indicated by a value obtained by the following method. That is, a statistical method based on the actual particle diameter (major axis diameter) and the number of particles obtained by calculating a value obtained by calculating the particle diameter (major axis diameter) of the particles shown in the above enlarged photograph. According to logarithmic normal probability paper, the particle diameter (major axis diameter) is plotted on the horizontal axis and the cumulative number of particles belonging to each of the predetermined particle diameter (major axis) sections (under the cumulative sieve) is plotted on the vertical axis in percentage. To do.
[0107]
The value of the particle diameter (major axis diameter) corresponding to the number of particles of 50% and 84.13% is read from this graph, and the geometric standard deviation value = the particle diameter (long) at 84.13% under the integrated sieve. (Axial diameter) / A value calculated according to the particle diameter (major axis diameter) (geometric mean diameter) at 50% under the total sieve. The closer the geometric standard deviation value is to 1, the better the particle size distribution.
[0108]
The specific surface area value was indicated by a value measured by the BET method.
[0109]
Each of the amount of Al and Si present inside the particle surface and the surface of the black magnetic particle powder and the amount of Si contained in the organosilane compound coated on the black magnetic particle powder are “fluorescence X-ray analyzer 3063M type” ( Rigaku Denki Kogyo Co., Ltd.) was used, and the measurement was performed in accordance with “General Rules for Fluorescence X-ray Analysis” of JIS K0119.
[0110]
The amount of carbon adhering to the black magnetic particle powder was determined by measuring the amount of carbon using “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 type” (manufactured by Horiba, Ltd.).
[0111]
The flowability of magnetic iron oxide particle powder, black magnetic particle powder, and black magnetic toner is determined by using a powder tester (trade name, manufactured by Hosokawa Micron Corporation), the angle of repose (degrees), the degree of compression (%), and the spatula angle (degrees). Each powder characteristic value of the degree of aggregation was measured, and each index was calculated by replacing each measured value with a numerical value of the same standard, and each index was indicated as a total fluidity index. The closer the fluidity index is to 100, the better the fluidity.
[0112]
The blackness of the magnetic iron oxide particle powder, black magnetic particle powder and black magnetic toner was measured by mixing 0.5 g of a sample and 1.5 cc of castor oil with a Hoover type Mahler to form a paste, and 4.5 g of clear lacquer was added to the paste. In addition, an application piece (coating thickness: about 30 μm) was prepared by kneading and coating, and applying onto a cast-coated paper using a 6 mil applicator, and the multi-light source spectrocolorimeter MSC-IS-2D ( Measured according to JIS Z 8729 using Suga Test Instruments Co., Ltd.^*Indicated by value.
[0113]
Where L^*The value represents lightness and L^*It shows that blackness is excellent, so that a value is small.
[0114]
The desorption rate of the carbon black fine particle powder adhering to the black magnetic particle powder was shown by the value obtained by the following method. The closer the desorption rate is to 0, the smaller the amount of carbon black fine particle powder desorbed from the particle surface.
[0115]
3 g of black magnetic particle powder and 40 ml of ethanol were placed in a 50 ml settling tube, subjected to ultrasonic dispersion for 20 minutes, and then allowed to stand for 120 minutes to separate the black magnetic particle powder and detached carbon black fine particle powder due to the difference in specific gravity. . Next, 40 ml of ethanol was again added to the black magnetic particle powder, and the mixture was further subjected to ultrasonic dispersion for 20 minutes and then allowed to stand for 120 minutes to separate the black magnetic particle powder from the detached carbon black fine particle powder. This black magnetic particle powder was dried at 100 ° C. for 1 hour, and the carbon content was measured using the above-mentioned “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 type” (manufactured by Horiba Seisakusho Co., Ltd.). The value was the desorption rate of the carbon black fine particle powder.
[0116]
Desorption rate of carbon black fine particle powder = {(Wa-We) / Wa} × 100
Wa: carbon black fine particle powder adhesion amount of black magnetic particle powder
We: Black magnetic particle powder adhesion amount of black magnetic particle powder after desorption test
[0117]
The dispersibility of the black magnetic particle powder in the binder resin was determined by photographing a cross section of the obtained black magnetic toner particle using an optical microscope (BH-2, manufactured by Olympus Optical Co., Ltd.). It was determined by counting the number of undispersed agglomerated particles at × 200) and evaluated in 5 stages. 5 indicates the best dispersion state.
1: 0.25mm²More than 50 per
2: 0.25 mm²10 or more and less than 50 per
3: 0.25 mm²5 to less than 10 per
4: 0.25mm²1 to less than 5 per
5: Undispersed material not recognized
[0118]
The average particle size of the black magnetic toner was measured using a laser diffraction particle size distribution analyzer (model HELOSLA / KA, manufactured by SYMPATEC).
[0119]
The volume resistivity of the black magnetic toner was measured by first measuring 0.5 g of a sample to be measured, and using a KBr tablet molding machine (manufactured by Shimadzu Corporation), 140 kg / cm.²A cylindrical sample to be measured was prepared by performing pressure molding at a pressure of 1 m.
[0120]
Next, after the sample to be measured was exposed to a temperature of 25 ° C. and a relative humidity of 60% for 12 hours or more, the sample to be measured was set between the stainless steel electrodes. A resistance value R (Ω) was measured by applying a voltage of 15V.
[0121]
Next, the area A (cm) of the upper surface of the sample to be measured (cylindrical)²) And thickness t (cm) were measured, and each measured value was inserted into the following equation to obtain a volume resistivity X (Ω · cm).
X (Ω · cm) = R × (A / t)
[0122]
The magnetic properties of the magnetic iron oxide particle powder and the black magnetic particle powder were measured using an “oscillating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.) up to an external magnetic field of 10 KOe. The magnetic properties of the black magnetic toner were measured over an external magnetic field of 1 KOe and 10 KOe.
[0123]
<Manufacture of black magnetic particle powder>
Spherical magnetite particle powder (average particle diameter 0.23 μm, geometric standard deviation value 1.42 and BET specific surface area value 9.2 m shown in the electron micrograph (× 20000) in FIG.²/ G, blackness L^*(20.6, flowability index 35, coercive force value 61 Oe, saturation magnetization value 84.9 emu / g at 10 KOe, residual magnetization value 7.8 emu / g at 10 KOe) The mixture was stirred using a stirrer and further passed through a “TK pipeline homomixer” (product name, manufactured by Tokushu Kika Kogyo Co., Ltd.) three times to obtain a slurry containing spherical magnetite particle powder.
[0124]
Next, the slurry containing the spherical magnetite particle powder was passed five times at a shaft rotational speed of 2000 rpm using a horizontal sand grinder “Mighty Mill MHG-1.5L” (product name, manufactured by Inoue Seisakusho Co., Ltd.). A dispersed slurry containing particle powder was obtained.
[0125]
The obtained dispersion slurry had a sieve residue of 0% at 325 mesh (aperture 44 μm). The dispersed slurry was filtered and washed with water to obtain a cake of spherical magnetite particles. After drying this spherical magnetite particle powder cake at 120 ° C., 11.0 kg of the dried powder was put into an edge runner “MPUV-2 type” (product name, manufactured by Matsumoto Casting Iron Works Co., Ltd.), and 30 kg / cm The mixture was agitated for 30 minutes to loosen the agglomeration of the particles.
[0126]
Next, a methyltriethoxysilane solution obtained by mixing and diluting 110 g of methyltriethoxysilane with 200 ml of ethanol is added to the spherical magnetite particle powder that has been deagglomerated while the edge runner is operated. The mixture was stirred for 60 minutes with a linear load of.
[0127]
Next, carbon black fine particle powder (particle shape: granular, average particle diameter 0.022 μm, geometric standard deviation value 1.68, BET specific surface area value 134 m shown in the electron micrograph (× 20000) of FIG.²/ G, blackness L^*Value 16.6) 990 g was added over 10 minutes while running the edge runner, and further mixed and stirred for 60 minutes at a linear load of 60 kg / cm to adhere the carbon black fine particle powder to the methyltriethoxysilane coating. Thus, black magnetic composite particle powder was obtained.
[0128]
The obtained black magnetic composite particle powder was aged at 105 ° C. for 60 minutes using a dryer, and the remaining water, ethanol, and the like were volatilized. This black magnetic particle powder had an average particle diameter of 0.24 μm as shown in the electron micrograph (× 20000) of FIG. The black magnetic particle powder has a geometric standard deviation value of 1.42 and a BET specific surface area value of 10.2 m.²/ G, fluidity index 46, blackness L^*The magnetic properties are 18.5, the carbon black desorption rate is 7.5%, and the magnetic properties are such that the coercive force value is 61 Oe, the saturation magnetization value at 10 KOe is 77.3 emu / g, and the residual magnetization value at 10 KOe is 7.1 emu. The coating amount of the organosilane compound produced from methyltriethoxysilane was 0.31% by weight in terms of Si. Also from the electron micrograph shown in FIG. 3, since almost no carbon black fine particle powder is observed, it can be seen that almost all of the carbon black fine particle powder is attached to the organosilane compound coating formed from methyltriethoxysilane. It was.
[0129]
<Production of black magnetic toner containing black magnetic particle powder>
400 g of the above black magnetic particle powder, 540 g of styrene-butyl acrylate-methyl methacrylate copolymer resin (molecular weight 130,000, styrene / butyl acrylate / methyl methacrylate = 82.0 / 16.5 / 1.5), 60 g of polypropylene wax (molecular weight) 3,000) and 15 g of the charge control agent were put into a Henschel mixer, and the mixture was stirred and mixed at a temperature of 60 ° C. for 15 minutes. The obtained mixed powder is melt-kneaded at 140 ° C. with a continuous biaxial kneader (T-1), and the obtained kneaded product is cooled, coarsely pulverized and finely pulverized in air, and then classified into black. A magnetic toner was obtained.
[0130]
The obtained black magnetic toner has an average particle size of 9.7 μm, a dispersibility of 5, a fluidity index of 73, a blackness of L^*The value is 18.3 and the volume resistivity value is 1.0 × 10¹⁴Ω · cm, coercive force value of 60 Oe, saturation magnetization value at 10 KOe is 32.6 emu / g, residual magnetization value at 10 KOe is 4.3 emu / g, saturation magnetization value at 1 KOe is 25.9 emu / g, residual magnetization at 1 KOe The value was 3.5 emu / g.
[0131]
[Action]
The most important point in the present invention is that the magnetic iron oxide particle powder having an average particle diameter of 0.055 to 0.95 μm, and if necessary, aluminum hydroxide, aluminum oxide on the surface of the magnetic iron oxide particle powder, An organosilane compound produced from alkoxysilane is coated on the particle surface of any one of magnetic iron oxide particles coated with one or more selected from silicon hydroxide and silicon oxide. A black magnetic composite particle powder in which carbon black fine particle powder having an average particle size of 0.002 to 0.05 μm is adhered to the organosilane compound coating, and the total amount of the carbon black fine particle powder is magnetic iron oxide The black magnetic particle powder, which is 1 to 25 parts by weight with respect to 100 parts by weight of the particle powder, has excellent fluidity and blackness, and is the surface of the particle. This is the fact that there are few carbon black fine particle powders to be detached. This is the fact that the black magnetic particle powder is excellent in dispersibility in the binder resin when the black magnetic toner is produced.
[0132]
Regarding the reason why the flowability of the black magnetic particle powder is excellent, the present inventor found that the carbon black fine particle powder that normally behaves as an aggregate due to the fine particles is the black magnetic particle powder according to the present invention. Is uniformly and densely attached to the surface of the magnetic iron oxide particle powder, so that the carbon black fine particle powder is present in a dispersed state close to the primary particles, and a large number of fine irregularities are present on the surface of the magnetic iron oxide particle. It is thought to be due to forming.
[0133]
As for the reason why the blackness of the black magnetic particle powder is excellent, the present inventor cancels the color of the core particle powder by the carbon black fine particle powder uniformly and densely attached to the particle surface of the magnetic iron oxide particle powder, This is thought to be due to the original color of the carbon black fine particle powder.
[0134]
As for the reason why there are few carbon black fine particle powders desorbed from the particle surface of the black magnetic particle powder, the present inventor explained that the metal element such as Si, Al, Fe, etc. contained in the inside or the surface of the magnetic iron oxide particle powder. Metallosiloxane bond (≡Si-OM) (where M is an iron-based black particle such as Si, Al, Fe, etc.) It is considered that the organosilane compound to which the carbon black fine particle powder is attached is firmly bonded to the particle surface of the magnetic iron oxide particle powder. .
[0135]
The reason for the excellent dispersibility of the black magnetic particle powder in the binder resin during the production of the magnetic toner is that the present inventor attributed that the carbon black fine particle powder desorbed from the particle surface of the black magnetic particle powder is small. In addition, the dispersion in the system is not hindered by the carbon black fine particle powder, and the carbon black fine particle powder adheres to the particle surface of the black magnetic particle powder, resulting in irregularities on the particle surface and suppressing contact between the particles. I think it will be done.
[0136]
The fact that the black magnetic toner according to the present invention obtained using the black magnetic particle powder is excellent in fluidity and blackness.
[0137]
Regarding the reason why the flowability of the black magnetic toner is excellent, the present inventor has found that the black magnetic particle powder in which the carbon black fine particle powder is uniform and present in a large amount is exposed on the surface of the black magnetic toner, and the This is thought to be due to the formation of fine irregularities.
[0138]
The reason why the black magnetic toner is excellent in blackness is that the present inventor believes that black magnetic particle powder having excellent blackness is blended in the black magnetic toner.
[0139]
【Example】
Next, examples and comparative examples are given.
[0140]
Magnetic iron oxide particles 1-4
Various magnetic iron oxide particle powders obtained by a known production method were prepared, and magnetic iron oxide particle powders that were deagglomerated were obtained in the same manner as in the above embodiment.
[0141]
Various characteristics of the magnetic iron oxide particle powder are shown in Table 1.
[0142]
[Table 1]

[0143]
Magnetic iron oxide particles 5
A slurry containing octahedral magnetite particle powder was obtained in the same manner as in the above-described embodiment using 20 kg of octahedral magnetite particle powder in which the aggregation of magnetic iron oxide particles 1 was unraveled and 150 l of water. The pH value of the redispersed slurry containing the octahedral magnetite particle powder obtained was 4.0. Next, water was added to the slurry to adjust the slurry concentration to 98 g / l. 150 l of this slurry was heated to 60 ° C., and 2722 ml of 1.0 mol / l aluminum sulfate solution (corresponding to 1.0 wt% in terms of Al with respect to octahedral magnetite particle powder) was added to the slurry, After maintaining for 30 minutes, the pH value was adjusted to 7.5 using an aqueous sodium hydroxide solution. Subsequently, in this slurry, 254 g of No. 3 water glass (on the octahedral magnetite particles, SiO 2₂(Corresponding to 0.5% by weight in terms of conversion) and aging for 30 minutes, and then adjusting the pH value to 7.5 with acetic acid. This state was maintained for 30 minutes, followed by filtration, washing with water, drying and pulverization to obtain octahedral magnetite particle powder whose particle surface was coated with aluminum hydroxide and silicon oxide.
[0144]
The main production conditions at this time are shown in Table 2, and various properties of the obtained octahedral magnetite particle powder are shown in Table 3.
[0145]
[Table 2]

[0146]
[Table 3]

[0147]
Magnetic iron oxide particles 6-8
Surface-treated magnetic iron oxide particles were obtained in the same manner as the magnetic iron oxide particles 5 except that the types of magnetic iron oxide particles and the types and amounts of additives in the surface treatment step were varied.
[0148]
Table 2 shows the main treatment conditions at this time, and Table 3 shows various properties of the obtained magnetic iron oxide particles.
[0149]
Examples 1-8, Comparative Examples 1-5
Types of particles to be treated, presence / absence of alkoxysilane in the coating process with organosilane compound, type and addition amount, edge runner treatment conditions, type and addition amount of carbon black fine particle powder in the adhesion process of carbon black fine particle powder, depending on edge runner A black magnetic composite particle powder was obtained in the same manner as in the above embodiment except that the treatment conditions were changed. As for the black magnetic composite particle powder obtained in each of Examples 1 to 8, almost no carbon black fine particle powder was observed as a result of electron microscope observation. It was confirmed that it adhered to the resulting organosilane compound coating.
[0150]
Table 4 shows the characteristics of the carbon black fine particles A to C used.
[0151]
[Table 4]

[0152]
Table 5 shows the main treatment conditions at this time, and Table 6 shows the characteristics of the obtained black magnetic composite particle powder.
[0153]
Comparative Example 1 is a treated particle powder obtained by mixing and stirring spherical magnetite particle powder and carbon black fine particle powder with an edge runner without coating with alkoxysilane. An electron micrograph (× 20000) of this treated particle powder is shown in FIG. As shown in the electron micrograph of FIG. 4, it was confirmed that the carbon black fine particle powder was not attached to the particle surface of the spherical magnetite particle powder, and both particle powders were mixed apart.
[0154]
[Table 5]

[0155]
[Table 6]

[0156]
<Manufacture of black magnetic toner>
Examples 9-16 and Comparative Examples 6-14
Black magnetic composite particle powder of Examples 1 to 8, magnetic iron oxide particle powder of core particles 1 to 4, mixed powder of magnetic iron oxide particle powder and carbon black fine particle powder of Comparative Example 1, and black of Comparative Examples 2 to 5 Using the magnetic particle powder, a black magnetic toner was obtained in the same manner as in the above embodiment.
[0157]
Tables 7 and 8 show the main production conditions and various characteristics at this time.
[0158]
[Table 7]

[0159]
[Table 8]

[0160]
【The invention's effect】
Since the black magnetic particle powder according to the present invention is excellent in fluidity and blackness, and has a low dispersibility in the binder resin due to a small amount of carbon black fine particle powder that is detached from the particle surface. It is suitable as a black magnetic particle powder for high-quality and high-speed black magnetic toner.
[0161]
Moreover, since the black magnetic particle powder according to the present invention is excellent in dispersibility, it is easy to handle and excellent in workability, and is industrially preferable.
[0162]
The black magnetic toner using the black magnetic particle powder having excellent fluidity and blackness is also excellent in fluidity and blackness. It is preferable as a toner.
[0163]
In addition, the black magnetic toner according to the present invention is separated and independently present in the black magnetic particle powder exposed on the surface of the magnetic toner particle due to the excellent dispersibility of the black magnetic particle powder. Therefore, there is no decrease in the volume resistivity due to the presence of the carbon black fine particle powder, and it is suitable as a high resistance or insulating magnetic toner.
[0164]
[Brief description of the drawings]
[0165]
FIG. 1 is an electron micrograph (× 20000) showing the particle structure of spherical magnetite particle powder used in an embodiment of the invention.
[0166]
FIG. 2 is an electron micrograph (× 20000) showing the particle structure of the carbon black fine particle powder used in the embodiment of the invention.
[0167]
FIG. 3 is an electron micrograph (× 20000) showing the particle structure of the black magnetic particle powder obtained in the embodiment of the invention.
[0168]
FIG. 4 is an electron micrograph (× 20000) showing the particle structure of a mixed powder of spherical magnetite particle powder and carbon black fine particle powder shown for comparison.

Claims (3)

The surface of the magnetic iron oxide particles having an average particle size of 0.055 to 0.95 μm is coated with an organosilane compound generated from the alkoxysilane shown in Chemical Formula 1 , and the organosilane compound coating has an average particle size of 0.00. Black magnetic composite particle powder to which carbon black fine particle powder of 002 to 0.05 μm is adhered, and the amount of carbon black fine particle powder adhered is 1 to 25 parts by weight with respect to 100 parts by weight of the magnetic iron oxide particle powder. A black magnetic particle powder for black magnetic toner, wherein
<Chemical formula 1>
R _a SiX _{4-a
R: -C 6 H 5, -} (CH 3) 2 CHCH 2, -n-C m H 2m + 1
_{X: -OCH 3, -OC 2 H} 5
m: an integer from 1 to 18
a: integer from 0 to 3 One kind selected from aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide as a lower layer on the particle surface of magnetic iron oxide particles having an average particle size of 0.055 to 0.95 μm or Two or more types are coated, and an organosilane compound generated from an alkoxysilane shown in Chemical Formula 2 is coated as an upper layer, and carbon black fine particle powder having an average particle size of 0.002 to 0.05 μm is coated on the organosilane compound coating. Black magnetic composite particle powder adhering, wherein the carbon black fine particle powder is attached in an amount of 1 to 25 parts by weight with respect to 100 parts by weight of the magnetic iron oxide particle powder. Magnetic particle powder.
<Chemical formula 2>
R _a SiX _{4-a
R: -C 6 H 5, -} (CH 3) 2 CHCH 2, -n-C m H 2m + 1
_{X: -OCH 3, -OC 2 H} 5
m: an integer from 1 to 18
a: integer from 0 to 3   A black magnetic toner using the black magnetic particle powder according to claim 1.

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