JP2008096789A - Black toner - Google Patents

Abstract

It is an object of the present invention to provide a black toner having a small particle diameter that achieves high resolution, is excellent in fine line reproducibility, is excellent in charging stability performance and durability stability performance.
In a black toner having black toner particles containing at least a binder resin and a colorant and at least one kind of inorganic fine powder,
The black toner has a magnetization value (σs) of 2.0 Am ² / kg or less at an external magnetic field of 796 kA / m,
The binder resin includes (a) a polyester resin, (b) a hybrid resin component having a polyester unit and a vinyl polymer unit, or (c) a mixture thereof.
The colorant comprises an iron-titanium composite oxide, contains a compound selected from a silane coupling agent and silicone oil, and contains 20 to 70 parts by mass with respect to 100 parts by mass of the binder resin.
The black toner particles are characterized in that the intensity ratio of Si to Ti in the fluorescent X-ray measurement is in the range of 2.0 to 5.0%.
[Selection figure] None

Description

  The present invention relates to a toner used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet recording method, and the like, and a manufacturing method thereof. Specifically, the present invention relates to a light printing machine, a copying machine, a toner image formed in advance on an electrostatic latent image carrier, and then transferred onto a transfer material to form an image and fixed under heat pressure to obtain an image. The present invention relates to black toner used in printers and fax machines.

  Conventionally, many methods are known as electrophotographic methods. In general, the surface of a latent image carrier made of a photoconductive material is uniformly charged by corona charging or direct charging by a charging roller or the like. After that, an electric latent image is formed on the latent image carrier by irradiation of light energy, etc., and then this electric latent image is developed with positively or negatively charged toner to form a toner image. Accordingly, after transferring the toner image to a transfer material such as paper, the toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy. The toner remaining without being transferred to the transfer material at the time of transfer is cleaned by various methods, and the above steps are repeated.

  Development methods for visualizing the electric latent image are roughly classified into a dry development method and a wet development method. The dry development method is divided into a method using a two-component developer composed of toner and carrier and a method using a one-component developer composed only of toner.

  In recent years, image forming apparatuses using electrophotography such as printers and copiers are receiving various requests such as downsizing and weight reduction, high speed and high productivity, energy saving, high reliability, low price, and maintenance-free. Therefore, it is required to form a higher resolution image. In particular, an image formed with black toner is required to be reproduced very finely and faithfully even in a fine portion not only in a black and white image forming apparatus but also in a full color image forming apparatus. For this reason, the toner needs further improvement in development stability and charging stability.

  The toner used in these image forming apparatuses is generally formed by dispersing toner particles in which a colorant such as a dye or pigment, a wax as a release agent, a charge control agent, and the like are dispersed in a thermoplastic resin. If necessary, an inorganic fine powder such as silica is attached to or adhered to the surface of the substrate.

  As the colorant used for the black toner, generally, a black colorant such as carbon black or magnetite is used. Carbon black has good blackness at a relatively low price, but its dispersibility in the binder resin may be low, and the carbon black exposed on the surface will cause image quality deterioration such as fogging and durability deterioration. There was a problem. Further, since carbon black has conductivity, black toner has conductivity, and development stability and charging stability are likely to be lowered. Further, when used in a full-color image forming apparatus, the transferability is different from other color toners such as cyan toner, magenta toner, and yellow toner, which causes deterioration in image quality.

  On the other hand, magnetite is often used as a colorant and a magnetic substance in a magnetic toner for a magnetic one-component development system. Magnetite has a relatively large electrical resistance value compared to carbon black, and relatively good development stability and charging stability can be obtained, but the electrical resistance value and coloring power still have points to be improved. . In particular, when full-color image formation is performed, magnetite has higher conductivity than pigments used for color toners, and hardly exhibits the same electrostatic behavior.

  Also, since magnetic toner generally contains a large amount of magnetite, it is difficult to improve the low-temperature fixing performance of the toner. In particular, when used in a full-color image forming apparatus, since the fixability of other color toners such as cyan toner, magenta toner, and yellow toner differs from magnetic toner, the glossiness of the image tends to be non-uniform.

  Furthermore, although the magnetic toner used for the magnetic one-component development method is stable in development, the chargeability is not sufficient. For example, when combined with a non-magnetic two-component color toner, carbon Similar to the case of using black, image deterioration due to a difference in transferability is likely to occur. In addition, when magnetic toner is used in a two-component development method, the chargeability is improved, but the agent circulation due to the magnetization of the toner is likely to be insufficient, and the toner tends to adhere to a magnetic carrier or a developing roll as a developer support. In some cases, the image deteriorates during durability.

  In order to solve these problems, a toner using a nonmagnetic or weakly magnetic black pigment has been proposed (for example, Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4). These toners have a small saturation magnetization and can be used in a two-component development system. However, according to the study by the present inventors, these toners have insufficient blackness of the black colorant, the reflection density is sufficiently high, and high-quality black characters and fine lines cannot be expressed. In addition, even when the black pigment itself has a sufficiently high degree of blackness, if the black pigment is dispersed in the binder resin, a problem that a sufficient image density cannot be obtained with a black toner alone or a red-black image can be obtained. There was a problem of becoming.

Further, a toner containing a low magnetization metal oxide and defining the color of a fixed image has been proposed (Patent Document 5). However, the above metal oxide is reddish black and cannot be used substantially for black toner unless used in combination with a blue pigment. A colorant has also been proposed (for example, Patent Document 6). However, when the magnetization is lowered, a certain level of image density is obtained in the solid image portion, but there is a problem that the halftone portion is reddish. A black pigment powder using an iron-titanium composite oxide and having a saturation magnetization of 5 to 40 Am ² / kg has also been introduced (for example, Patent Document 7). However, as described above, when used in a two-component development method or in combination with a color toner in a full-color image forming apparatus, it is more severe when used in a one-component development system or cleanerless system aimed at further miniaturization. It was a thing.

  When producing a black toner using a vinyl resin as a binder resin for a magnetic black toner, the colorant particles dispersed in the toner binder resin can be obtained by using a colorant whose surface is hydrophobized. It is known that the property can be improved (for example, Patent Document 8). Further, a magnetic black toner using a polyester-based resin in which the colorant surface is subjected to a hydrophilic treatment in order to improve dispersibility is known, but the dispersibility has not been improved sufficiently yet. The colorant used for the black toner generally tends to aggregate and is not easy to uniformly disperse in the resin. When the surface of the colorant is made hydrophilic, the dispersibility in the resin is improved, and self-aggregation of the colorant is likely to occur.

Japanese Patent Laid-Open No. 2002-221821 JP 2004-102154 A Japanese Patent Laid-Open No. 3-220666 JP 2004-54094 A JP 2002-196528 A JP-A-3-002276 JP 2004-161608 A JP 2005-107520 A

  As described above, non-magnetic or weakly magnetic black pigments have been proposed, but the problems of colorants, such as increasing coloring power, increasing blackness, and lowering the magnetization value, developability, However, the problems such as transferability and fixability, which are manifested in the production of toner, are not compatible. For example, when the coloring power of the colorant is low, it is possible to solve these problems by performing (1) increasing the amount of the colorant in the toner, (2) increasing the amount of toner loaded, etc. Although it is possible, when the amount of the colorant as in (1) is increased, deterioration in image quality is promoted when used in a non-magnetic contact one-component developer and cleanerless system as shown in FIG. . In the process cartridge shown in FIG. 2, a developing roller (elastic roller) 19 is pressed against the developing unit 15 so that a nip portion is formed on the photosensitive drum 10. An application roller 12 is provided in pressure contact. Further, a charging roller 11 and a cleaning blade 13 are provided in pressure contact with the photosensitive drum 10. It is considered that the colorant exposed on the toner surface was liberated and caused member contamination at the press contact portion. Further, when the toner adheres to the non-image area or the amount of untransferred toner increases, the toner consumption tends to increase.

  In addition, as the density of the black toner increases, the electrical behavior of development and transfer changes, and defects such as image unevenness and image omission tend to occur, especially when used as a black toner for full-color electrophotographic methods. became. Similarly, in the case of (2), problems are likely to occur in each process of fixing, developing, and transferring.

  Therefore, a black toner having a strong coloring power and a high blackness is required with the smallest amount of colorant. At the same time, it is necessary to prevent self-aggregation of the colorant, improve dispersibility in the binder resin, and suppress exposure to the toner surface.

  Further, when these non-magnetic or weak magnetic colorants are used for the black toner and used as a full-color colorant, there is a problem that the black background is not smooth. One cause of the roughness is due to the gloss difference with other color toners such as cyan toner, magenta toner, and yellow toner. In this regard, the molecular weight of the binder resin of the black toner is controlled, and the binder resin is further configured. By changing the monomer species to be used, it is possible to reproduce the uniform gloss by controlling the viscoelastic characteristics and the melting point. However, even in such a case, it was difficult to suppress the halftone roughness of the black background. The reason for this is that even if the viscoelastic properties and melting point are controlled in the solid part, the transferability and especially the fixing property at low temperature when isolated dots are different between the black toner and the color toner, and particularly appear in the halftone part. It is done.

  An object of the present invention is to solve the above-mentioned problems, to achieve high resolution, to provide a black toner having a small particle diameter which is excellent in fine line reproducibility, excellent in charging stability performance and durability stability performance.

  In addition, the present invention suppresses graininess (roughness) from a low image density area to a high image density area, and can form a high-quality black image having no redness or blueness. It is an object to provide a toner.

  The present invention also provides a black toner that has the same transferability as that of other color toners, has excellent gloss, and can stably form a high-resolution full-color image even in a color image forming apparatus. The task is to do.

  Furthermore, the object of the present invention is to achieve high image resolution and minimize deterioration of the photosensitive drum even when aiming to reduce the size of the color image forming apparatus such as space saving and maintenance-free. It is possible to provide an image forming apparatus which can be used and has excellent durability.

According to the present invention, in a black toner having black toner particles containing at least a binder resin and a colorant and at least one kind of inorganic fine powder,
The black toner has a magnetization value (σs) of 2.0 Am ² / kg or less at an external magnetic field of 796 kA / m,
The binder resin includes (a) a polyester resin, (b) a hybrid resin component having a polyester unit and a vinyl polymer unit, or (c) a mixture thereof.
The colorant comprises an iron-titanium composite oxide, contains a compound selected from a silane coupling agent and silicone oil, and contains 20 to 70 parts by mass with respect to 100 parts by mass of the binder resin.
The black toner particles are characterized in that the intensity ratio of Si to Ti in the fluorescent X-ray measurement is in the range of 2.0 to 5.0%.

  The surface of the colorant is covered with a silane coupling agent having a polar group selected from an epoxy group, a carboxyl group, an amino group, a methacryloxy group, and an acryloxy group, or silicone oil.

  As the colorant, a compound having a structure shown below is used.

The water vapor adsorption amount when the relative pressure of the colorant is 0.5 is 0.4 to 0.6 mg / m ² .

The colorant contains FeTiO ₃ —Fe ₂ O ₃ solid solution as a main component.

  The number average particle diameter of the colorant is 0.1 to 0.3 μm, and the standard deviation σ / number average particle diameter of the colorant is 45% or less.

  The colorant contains an iron-titanium composite oxide and is contained in an amount of 25 to 60 parts by mass with respect to 100 parts by mass of the binder resin.

  The acid value of the binder resin is 15 to 40 mgKOH / g.

The black toner has a dielectric loss ratio (tan δ) at 10 ⁵ Hz in the range of 0.005 to 0.010.

The magnetization value (σs) of the toner at an external magnetic field of 796 kA / m is 1.5 Am ² / kg or less.

  The black toner contains a release agent, and the release agent has an endothermic peak at 60 to 90 ° C. in an endothermic curve in differential thermal analysis (DSC) measurement.

  The black toner contains an organometallic compound, and the organometallic compound is an aromatic carboxylic acid derivative selected from an aromatic oxycarboxylic acid and an aromatic alkoxycarboxylic acid, or a metal compound of the aromatic carboxylic acid derivative. It is.

  When the black toner of the present invention is used, a toner having excellent durability with little image deterioration during continuous printing can be obtained. In particular, the durability can be improved by a cleanerless type or non-magnetic one-component type developing device.

  According to the present invention, black toner capable of forming a high-quality black image having no redness or bluishness while suppressing graininess (roughness) from a low image density region to a high image density region. Can provide.

  The present invention also provides a black toner that has the same transferability as that of other color toners, has excellent gloss, and can stably form a high-resolution full-color image even in a color image forming apparatus. it can.

  As a result of intensive studies, the present inventors have found that when an iron-titanium composite oxide is used as a colorant, (1) the colorant can be prevented from being detached from the toner by controlling the dispersion state in the toner. It is possible to suppress the contamination of the member and improve the durability, and (2) the colorant characteristics such as coloring power and blackness can be sufficiently extracted, and the characteristics relating to electrophotography such as development, transfer and fixing are also It has been found that a black toner having sufficiently improved characteristics can be supplied.

  In the present invention, in order to control the dispersion state of the colorant, attention was paid to the chemical composition of the binder resin and the colorant surface. By applying a compound having a functional group with high affinity to each of them, that is, a surface treatment agent, to the colorant, the dispersibility of the colorant can be increased and self-aggregation of the colorant can be prevented. If the amount of the surface treatment agent is insufficient, a sufficient effect for dispersion control cannot be obtained, and if it is excessive, self-aggregation tends to occur.

  By combining the polarity of the surface of the iron-titanium composite oxide with that of the resin, it is considered that the affinity of the interface between the iron-titanium composite oxide and the resin is increased and the dispersibility of the colorant is improved. The polar group such as carboxyl group and ester bond that the resin has and the polar group that the surface treatment agent has due to electrostatic interaction, although it is weak, there are many points of interaction, so it plays a role as a whole. This is probably because of this.

  The surface treatment agent used in the present invention is a compound called a silane coupling agent or a silane monomer, and an alkoxysilane having a polar group selected from an epoxy group, a carboxyl group, an amino group, a methacryloxy group, and an acryloxy group is preferable. For example, compounds as listed below can be used.

  Among these, it is preferable to use a silane coupling agent having an epoxy group such as glycidoxypropyltrimethoxysilane and glycidoxypropyltriethoxysilane. It is considered that the affinity between the carbonyl carbon of the binder resin and the epoxy oxygen of the surface treatment agent is increased by electrostatic interaction, and the dispersibility is improved.

Further, a silicone oil may be used as the surface treatment agent, and a silicone oil having a polar group selected from an epoxy group, a carboxyl group, an amino group, a methacryloxy group, and an acryloxy group at the side chain or the terminal is desirable. For example, the following silicone oil can be used. In Formula 3, n represents a number average degree of polymerization. In order to apply uniformly, the viscosity of the silicone oil is preferably 4 cSt (mm ² / s) or less at 25 ° C. If it exceeds 4 cSt (mm ² / s), the viscosity increases and stirring becomes difficult. From the viewpoint of viscosity, n is preferably 6 or less. These surface treatment agents have both good adhesion to the surface of the iron-titanium composite oxide and affinity with the resin. Furthermore, instead of silicone oil, a silicone resin having a polar group selected from an epoxy group, a carboxyl group, an amino group, a methacryloxy group, and an acryloxy group at the side chain or terminal may be used.

  Of these, silicone oil having a glycidyl group is particularly preferable. For example:

  When these surface treatment agents and iron-titanium composite oxide are combined, the surface of the iron-titanium composite oxide can be uniformly coated. The silanol group produced by hydrolysis of alkoxysilane is considered to have a high affinity with the solid solution of titanium-oxygen, and in particular, expresses a good affinity with the solid solution of titanium-oxygen on the surface.

  The black toner particles of the black toner of the present invention preferably have a Si to Ti intensity ratio in the range of 2.0 to 5.0% in the fluorescent X-ray measurement. Si atoms and silanol groups have relatively good affinity with Ti. When the strength ratio of Si to Ti is less than 2.0%, the durability is lowered, particularly when a nonmagnetic contact one-component developing device is used, and the conventional problem cannot be solved. At this time, the amount of the surface treatment agent for the colorant is insufficient, the affinity for the binder resin is not increased, the dispersibility of the colorant in the binder resin is not sufficient, and the colorant is detached. Conceivable. On the other hand, when the strength ratio of Si to Ti exceeds 5.0%, the colorant tends to self-aggregate, which may cause problems such as a decrease in blackness and a decrease in coloring power. The amount is excessive. Furthermore, when the environment such as atmospheric temperature and humidity changes, there arises a problem that it becomes difficult to obtain a stable image. This is presumably because the colorant exposed on the surface of the black toner adsorbs water vapor in the atmosphere, so that the chargeability tends to decrease.

  In order to satisfy the present invention, the amount of the surface treatment agent used is preferably in the range of 0.20 to 1.00% by mass with respect to the iron-titanium composite oxide. By being in this range, it is considered that the surface treatment agent can form a stable layer on the colorant surface.

  It was found that the dispersibility of the colorant in the binder resin is improved by using the surface treatment agent as described above and keeping the treatment amount within the above range, and the present invention has been achieved.

  Regarding the surface treatment method, the iron-titanium composite oxide is dispersed in an aqueous medium while maintaining the primary particle size, and at the same time, the surface treatment is performed while hydrolyzing the coupling agent. The surface treatment method in an aqueous medium is less likely to cause coalescence between the colorants compared to the treatment in the gas phase, and the surface treatment is performed in a state of almost primary particles. Processing is achieved.

  The method of treating the iron oxide surface while hydrolyzing the coupling agent in an aqueous medium does not require the use of a coupling agent that generates gas, such as chlorosilanes and silazanes. Furthermore, a high-viscosity coupling agent, which has been difficult to achieve satisfactory treatment because the colorant particles can be easily combined with each other in the gas phase, has a great effect on the surface treatment.

  In the present invention, the aqueous medium is a medium containing water as a main component. Specific examples of the aqueous medium include water itself, water added with a small amount of a surfactant, water added with a pH adjusting agent, and water added with an organic solvent. The surfactant is preferably added in an amount of 0.1 to 5% by mass with respect to water.

  Stirring is sufficiently performed so that the colorant particles can maintain the primary particles in the aqueous medium with a mixer having a stirring blade (specifically, a high shear force mixing device such as an attritor or a TK homomixer). Good to do.

  The binder resin of the present invention desirably contains a polyester resin. In general, it is known that a toner using a polyester resin is excellent in fixability. Toner used for full-color copying machines and full-color printers is required to have low-temperature fixability as well as gloss control, and preferably has a polyester resin that can be fixed with a small amount of heat.

  Moreover, since the polyester resin has a polar ester bond, the dispersibility of the colorant of the present invention can be improved. Usually, when the toner material kneaded material is pulverized, the toner material kneaded material is easily broken at the interface between the resin and the colorant. Therefore, the colorant is often exposed on the toner particle surface. When the colorant is exposed on the surface of the toner particles, when used in a two-component cleanerless system or a non-magnetic contact one-component system, there is a problem that the durability is lowered as described above.

  The toner of the present invention may be blended with a hybrid resin component in addition to the polyester resin. By blending the hybrid resin component, the resin can be easily pulverized during toner production. As a result, the exposure of the colorant can be further suppressed.

  When the surface-treated iron-titanium composite oxide used in the present invention and a resin having a vinyl copolymer such as styrene and acrylic acid were used, the dispersibility of the colorant was not significantly improved.

According to the present invention, in the toner used for one-component or two-component development, the black toner has a magnetization value (σs) at an external magnetic field of 796 kA / m of 2.0 Am ² / kg or less, more preferably 1.5 Am ² / kg. In the following, in a two-component system, it is more preferable to set it to 1.0 Am ² / kg or less.

In a one-component developer, when the magnetization value (σs) exceeds 2.0 Am ² / kg, streak stains may occur at the rear end of the image.

In the two-component development, when the magnetization value (σs) exceeds 2.0 Am ² / kg, the presence of toner released from the development carrier is increased on the developer carrier (developing roller) of the developing device. In this case, even if the cycle progresses, a phenomenon called so-called spinning occurs that is not used for development. Due to the presence of toner in the developer carrier, charge transfer between the developer carrier and the development carrier becomes insufficient, resulting in a decrease in the electric field strength in the development region, and image defects such as a reduction in development efficiency and ghosting. It becomes easy to cause.

The above-mentioned problems can be solved by optimizing the colorant used in the black toner, the amount thereof, and the binder resin as described above. However, the black toner of the present invention has a dielectric loss ratio at 10 ⁵ Hz ( By setting tan δ to 0.010 or less, an image with less roughness can be obtained. When the dielectric loss ratio is larger than 0.010, the transfer efficiency is lowered and the quality of characters is lowered. Further, “fogging” in which the toner adheres to the non-image portion becomes conspicuous and is not desirable.

  The colorant of the present invention forms iron hydroxide colloidal particles from iron (II) ions in the presence of an alkali in an aqueous medium, and obtains an iron-titanium composite oxide by doping with titanium. Iron-titanium composite oxide particles having a sharp particle size distribution can be obtained.

  The colorant according to the present invention preferably has a standard deviation / number average diameter (σ / Dp) of 45% or less. In order to increase the dispersibility of the colorant, it is desirable that (σ / Dp) is in the above range. When (σ / Dp) exceeds 45%, the sintered portion due to heat treatment increases, making it difficult to obtain the desired blackness. In addition, the dispersibility in the resin is deteriorated, making it difficult to obtain a desired image density. Preferably it is 40% or less. The standard deviation σ of the particle diameter of the colorant according to the present invention is preferably 0.01 to 0.18 μm.

  When the above binder resin and a colorant whose surface has been modified with an appropriate amount of a surface treatment agent are used, image deterioration is suppressed during continuous printing, and durability is improved. In particular, when used in a cleanerless system and a non-magnetic contact one-component developing device, the effect is easily obtained. The colorant released from the black toner tends to cause image deterioration such as a decrease in dot reproducibility by scratching the photosensitive drum or scraping a member in the developing unit. In the black toner of the present invention, the detachment of the colorant can be suppressed and the durability can be improved. Further, by controlling the dispersion state of the colorant in the toner, a toner having sufficient blackness can be obtained.

  On the other hand, it is effective to use a colorant that has a uniform particle size and is less likely to cause aggregation during toner production. With respect to the iron-titanium composite oxide that is the colorant of the present invention, it is possible to obtain a colorant having a uniform particle size without forming aggregates by lowering the temperature during heating and firing. Furthermore, the surface treatment agent selected from the silane coupling agent and silicone oil used for the colorant has the property of melting and crushing at the temperature during kneading, and can suppress the self-aggregation of the colorant when it is made into a toner. It became so.

  Next, the composite oxide of iron titanium that is a colorant used in the present invention will be described in more detail.

  The black toner preferably has a maximum peak at 2θ = 32.5 to 33.1 degrees in X-ray diffraction, and the half width of the peak is preferably 0.25 degrees or less. More preferably, it is 0.23 degrees or less, and further preferably 0.20 or less. This is possible by controlling the crystal of the complex oxide of iron titanium which is the colorant of the present invention.

The colorant of the present invention has a crystal structure containing a FeTiO ₃ —Fe ₂ O ₃ solid solution as a main component. This compound has a corundum structure in which Fe of hematite (Fe ₂ O ₃ ) having a trigonal structure is replaced with Ti. The (104) plane, which is the main peak in X-ray diffraction, is hematite and has a peak at 2θ = 33.1 to 33.2. As the replacement of Fe atoms with Ti atoms proceeds, the diffraction angle in X-ray diffraction shifts to the narrow angle side. When the half width of this peak exceeds 0.25 degrees, the content of titanium present in the colorant is non-uniformly present, and the dispersion in the toner tends to be non-uniform. For this reason, it is difficult to obtain a sufficient density, and toner characteristics such as fixing and transfer performance tend to be inferior. In addition, the full width at half maximum tends to increase due to the reduction of the single crystallite. In this case, the toner tends to be reddish, and it becomes difficult to obtain a good black toner. In the colorant of the present invention, when one particle is composed of polycrystals and the constituent crystallite is small, a colorant having sufficient resistance is obtained by a decrease in resistance at the interface between the crystallites. Hateful. For this reason, the performance at the time of development and transfer is lowered, and when it is used in combination with color toner, it is easily recognized as image unevenness. In addition, when the crystallite is small, even when the particle size of the colorant which is a polycrystal is increased, it is easy to obtain a reddish colorant and it is difficult to obtain a colorant having good blackness.

The BET specific surface area of the iron-titanium composite oxide according to the present invention is preferably 3 to 15 m ² / g. When the BET specific surface area is less than 3 m ² / g, the particles become coarse particles and the coloring power decreases. If it exceeds 15 m ² / g, it is difficult to obtain the desired blackness. More preferably, it is 6-12 m < ² > / g, More preferably, it is 6.5-11 m < ² > / g.

The black colorant used in the present invention preferably has a water vapor adsorption amount of 0.4 to 0.6 mg / m ² per colorant unit area at 25 ° C. and 50% relative humidity. By being in this range, it is considered that the affinity between the colorant surface and the binder resin is increased, and the dispersibility is improved. When the water vapor adsorption amount is less than 0.4 mg / m ² , the toner is likely to be charged up in a low-temperature and low-humidity environment, and the durability may be reduced. Further, when the water vapor adsorption amount exceeds 0.6 mg / m ² , fog may occur in a high temperature and high humidity environment. Preferably it is 0.4-0.6 mg / m < ² > in order to provide the dispersion control of this coloring agent, and environmental stability.

  The titanium content of the iron-titanium composite oxide according to the present invention is preferably 10 to 38 atomic%. When the titanium content is less than 10 atomic%, it becomes difficult to obtain particle powder having a desired blackness, and when the titanium content exceeds 38 atomic%, it is difficult to obtain a colorant having a high concentration.

The constituent phase of the iron-titanium composite oxide according to the present invention is preferably a FeTiO ₃ —Fe ₂ O ₃ solid solution. Further, it may be a mixture of two or more selected from compounds such as FeTiO ₃ —Fe ₂ O ₃ solid solution and Fe ₂ TiO ₅ , Fe ₂ TiO ₄ —Fe ₃ O ₄ solid solution, FeTiO ₃ , FeTiO _{4, and the} like. Spinel iron oxides such as Fe ₃ O ₄ and γ-Fe ₂ O ₃ , which are raw materials, may be present, but in order to lower the magnetization of the colorant and the magnetization of the toner, these abundances are made as much as possible. Less is better.

  As for the coloring power of the iron titanium complex oxide which concerns on this invention, 35-44 are preferable. When the coloring power exceeds 44, it is difficult to obtain a sufficient image density when the nonmagnetic black toner using the iron-titanium composite oxide is used. An iron-titanium composite oxide having a coloring power of less than 35 cannot be produced industrially. More preferably, it is 35-43.

  The iron-titanium composite oxide according to the present invention is desirably contained in an amount of 20 to 70 parts by mass with respect to 100 parts by mass of the binder resin. More preferably, it is 25 to 60 parts by mass. When the amount is less than 20 parts by mass, even when the iron-titanium composite oxide of the present invention is used, the image density tends to be low because the hiding power becomes insufficient. When the amount is more than 70 parts by mass, the density and blackness are excellent, but the fixing property is lowered, and the transfer performance is also lowered, which easily causes image unevenness and roughness. Although the dispersibility of the colorant is increased by applying a surface treatment, the liberated colorant may reduce the durability.

  The iron-titanium composite oxide according to the present invention includes one or more elements selected from Na, Mg, Al, Si, P, Mn, Co, Ni, Cu, and Zn in addition to iron titanium. And 5 atomic% or less may be included with respect to the total amount of titanium.

The iron-titanium composite oxide of the present invention may further contain a composite oxide containing Na, NaFeTi ₃ O ₈ . X-ray diffraction has a peak at 2θ = 28.5 to 29.5. With the addition amount of Na, the presence of the compound increased, and the X-ray intensity increased. The compound has a large blackness and makes it easy to achieve both a concentration and a color as compared with the case where the iron-titanium composite oxide FeTiO ₃ —Fe ₂ O ₃ solid solution is used alone. However, containing a large amount of Na in these composite oxides makes it difficult to satisfy the tint in the processing step, as the particles become finer. When Na is contained, it is desirable to appropriately adjust the Na content.

When NaFeTi ₃ O ₈ is contained, it can be achieved by adding a sodium compound to a black precipitate or an aqueous suspension containing them that forms a FeTiO ₃ —Fe ₂ O ₃ solid solution at the time of preparation. Examples of the sodium compound include sodium hydroxide, sodium sulfate, sodium carbonate, and sodium chloride.

  The toner of the present invention is a mixture of these raw materials, melted and kneaded, and then pulverized by mechanical impact to obtain a target particle size by air classification, suspension polymerization, dissolution suspension, emulsification A toner that obtains toner particles by granulation or the like can be used.

  In the present invention, the binder resin preferably contains (a) a polyester resin, (b) a hybrid resin component having a polyester unit and a vinyl polymer unit, or (c) a mixture thereof.

  The binder resin is mainly composed of a polyester resin, and particularly preferably contains a “polyester unit”. “Polyester unit” refers to a portion derived from polyester, and as a polyester monomer constituting the polyester unit, a polyhydric alcohol, a polycarboxylic acid, a polycarboxylic anhydride, or two or more carboxyl groups are included. Carboxylic acid components such as polycarboxylic acid esters can be used as raw material monomers.

Specifically, for example, as the dihydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis ( 4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2 -Alkylene oxide adducts of bisphenol A such as bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane;
Ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1, Examples include 6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, and hydrogenated bisphenol A.

  Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Can be mentioned.

  Examples of the carboxylic acid component include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as oxalic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; And succinic acid substituted with 12 to 12 alkyl groups or anhydrides thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid or anhydrides thereof;

  The polyester resin has a bisphenol A derivative represented by the following general formula (1) as an alcohol component, and a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof, or a lower alkyl ester thereof (for example, A polyester resin obtained by condensation polymerization of fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) as an acid component is preferable because it has good charging characteristics as a color toner.

〔式中、Ｒはエチレン基およびプロピレン基から選ばれる一種以上であり、ｘ、ｙは１以上の整数であり、かつｘ＋ｙの平均値は２〜１０である。〕

[In the formula, R is at least one selected from an ethylene group and a propylene group, x and y are integers of 1 or more, and the average value of x + y is 2 to 10. ]

  Examples of the trivalent or higher polyvalent carboxylic acid component for forming a polyester resin having a crosslinking site include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2 , 4-Naphthalenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, and acid anhydrides and ester compounds thereof. The use amount of the trivalent or higher polyvalent carboxylic acid component is preferably 0.1 to 1.9 mol% based on the total monomers.

  In the hybrid resin of the present invention, it is preferable that the vinyl resin component and / or the polyester resin component contain a monomer component capable of reacting with both resin components. Examples of the monomer constituting the polyester resin component that can react with the vinyl polymer include unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid, and itaconic acid, or anhydrides thereof. Among the monomers constituting the vinyl polymer component, those capable of reacting with the polyester resin component include those having a carboxyl group or a hydroxy group, and acrylic acid or methacrylic acid esters.

  As a method for obtaining a hybrid resin, which is a reaction product of a vinyl resin and a polyester resin, a polymer containing a monomer component capable of reacting with each of the vinyl resin and the polyester resin listed above is present. A method obtained by polymerizing one or both resins is preferred.

As a polymerization initiator used when manufacturing the vinyl resin of this invention, the following are mentioned, for example. 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (-2,4-dimethylvaleronitrile), 2 , 2′-azobis (-2methylbutyronitrile), dimethyl-2,2′-azobisisobutyrate, 1,1′-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyro Nitrile, 2,2′-azobis (2,4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2,2′-azobis (2-methyl-propane), methyl ethyl ketone Ketone peroxides such as peroxide, acetylacetone peroxide, cyclohexanone peroxide;
2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-tert-butyl peroxide, tert -Butylcumyl peroxide, di-cumyl peroxide, α, α'-bis (tert-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5 5-trimethylhexanoyl peroxide, benzoyl peroxide, m-trioyl peroxide, di-isopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxide Sidicarbonate, di-2-ethoxyethyl peroxycarbonate, di-methoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, tert-butyl peroxyacetate, tert-butyl peroxyisobutyrate, tert-butyl peroxyneodecanoate, tert-butyl peroxy 2-ethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxybenzoate, tert-butyl Peroxyisopropyl carbonate, di-tert-butyl peroxyisophthalate, tert-butyl peroxyallyl carbonate, tert-amyl peroxy 2-ethylhexanoe Di-tert-butylperoxyhexahydroterephthalate, di-tert-butylperoxyazelate.

  Examples of the production method capable of preparing a preferable binder resin used in the toner of the present invention include the production methods shown in the following (1) to (6).

  (1) A method in which a vinyl resin, a polyester resin and a hybrid resin component are blended after production, and the blend is produced by dissolving and swelling in an organic solvent (for example, xylene) and then distilling off the organic solvent. The hybrid resin component is synthesized by separately producing a vinyl polymer and a polyester resin, then dissolving and swelling in a small amount of an organic solvent, adding an esterification catalyst and alcohol, and performing a transesterification reaction by heating. The ester compound used can be used.

  (2) A method for producing a polyester unit and a hybrid resin component in the presence of a vinyl polymer unit after the production. The hybrid resin component is produced by a reaction between a vinyl polymer unit (a vinyl monomer can be added if necessary) and a polyester monomer (alcohol, carboxylic acid) and / or polyester. Also in this case, an organic solvent can be appropriately used.

  (3) A method for producing a vinyl polymer unit and a hybrid resin component in the presence of a polyester unit after the production thereof. The hybrid resin component is produced by a reaction between a polyester unit (a polyester monomer can be added if necessary) and a vinyl monomer and / or a vinyl polymer unit.

  (4) After producing the vinyl polymer unit and the polyester unit, a hybrid resin component is produced by adding a vinyl monomer and / or a polyester monomer (alcohol, carboxylic acid) in the presence of these polymer units. Also in this case, an organic solvent can be appropriately used.

  (5) After producing the hybrid resin component, a vinyl monomer and / or polyester monomer (alcohol, carboxylic acid) is added to carry out addition polymerization and / or condensation polymerization to produce a vinyl polymer unit and a polyester unit. Is done. In this case, as the hybrid resin component, those produced by the production methods (2) to (4) can be used, and those produced by a known production method can be used as necessary. Furthermore, an organic solvent can be used as appropriate.

  (6) A vinyl polymer unit, a polyester unit, and a hybrid resin component are produced by mixing a vinyl monomer and a polyester monomer (alcohol, carboxylic acid, etc.) and continuously performing addition polymerization and condensation polymerization reaction. Furthermore, an organic solvent can be used as appropriate.

  In the production methods (1) to (5) above, the polymer unit having a plurality of different molecular weights and crosslinking degrees can be used as the vinyl polymer unit and / or the polyester unit.

  The black toner of the present invention desirably has a binder resin having a polar site such as an ester bond or a urethane bond. Therefore, the compound selected from the group consisting of a silane coupling agent and a silicone oil is used as the iron titanium composite oxide according to the present invention. It is considered that the surface of the colorant is close to the polarity of the binder resin and the dispersibility of the colorant is improved.

  The acid value of the binder resin in the present invention is preferably 15 to 40 mgKOH / g. By being in this range, the dispersibility of the colorant during the binding is improved. When the acid value of the binder resin is less than 15 mgKOH / g, an increase in the charge amount in durability, so-called charge-up is likely to occur, and it becomes difficult to maintain the image density over a long period of time. In addition, when the acid value of the binder resin exceeds 40 mgKOH / g, there is no tendency to charge up, but the tendency to decrease the charge amount particularly in a high temperature and high humidity environment, so-called “white background fogging” due to so-called charge-down occurs. As a result, the image quality is degraded. White background fogging is a phenomenon in which non-image areas are stained with a developer.

  Examples of the release agent used in the present invention include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight olefin copolymers, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; Oxides of such aliphatic hydrocarbon waxes; waxes based on fatty acid esters such as aliphatic hydrocarbon ester waxes; and fatty acid esters such as deoxidized carnauba wax that have been partially or fully deoxidized. It is done. Furthermore, a partially esterified product of a fatty acid such as behenic acid monoglyceride and a polyhydric alcohol; a methyl ester compound having a hydroxyl group obtained by hydrogenating vegetable oils and the like. Particularly preferred waxes are aliphatic hydrocarbon waxes such as paraffin wax, polyethylene wax, and Fischer-Tropsch wax that have a short molecular chain and little steric hindrance and excellent mobility.

  In the toner used in the present invention, a toner used for oilless fixing having a binder resin, a colorant, a release agent, and an inorganic fine powder is preferable. The binder resin contains a polyester unit, and the release agent is carbonized. It is a hydrogen-based wax, and in the endothermic curve in the differential thermal analysis measurement of the toner, the temperature of the maximum endothermic peak is preferably 60 ° C. to 90 ° C. When the temperature is lower than 60 ° C., the heat-resistant storage characteristics are inferior. For this reason, it is impossible to perform low-temperature fixing, which is desirable from the viewpoint of energy saving, and a load that requires a large pressure is required in the fixing configuration.

  The release agent used in the present invention preferably has a content of 1 to 10 parts by mass, and more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin. If the content is less than 1 part by mass, the releasability may not be exhibited well at the time of oilless fixing, or the low-temperature fixing property may not be satisfied. When it exceeds 10 parts by mass, the release agent tends to ooze out to the toner surface, and white spots may be deteriorated.

  Further, a wax as a release agent may be added as a wax dispersion master batch.

  As the wax dispersion masterbatch, one or more monomers selected from (i) polyester resin, (ii) hydrocarbon wax, (iii) styrene monomer, and (meth) acrylic acid monomer are used. It is preferable to have at least the synthesized copolymer and polyolefin.

  The toner of the present invention can be used in combination with a known charge control agent. Examples of such charge control agents include organometallic complexes, metal salts, and chelate compounds such as monoazo metal complexes, acetylacetone metal complexes, hydroxycarboxylic acid metal complexes, polycarboxylic acid metal complexes, and polyol metal complexes. In addition, carboxylic acid derivatives such as metal salts of carboxylic acids, carboxylic acid anhydrides and esters, and condensates of aromatic compounds are also included. As the charge control agent, phenol derivatives such as bisphenols and calixarenes are also used.

The charge control agent used in the present invention is preferably an aromatic carboxylic acid derivative selected from an aromatic oxycarboxylic acid and an aromatic alkoxycarboxylic acid, or a metal compound of the aromatic carboxylic acid derivative. The metal is preferably a divalent or higher valent metal atom. The following are mentioned as a bivalent metal. Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Pb ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ , Cu ²⁺ . As the divalent metal, Zn ²⁺ , Ca ²⁺ , Mg ²⁺ and Sr ²⁺ are preferable. Examples of the trivalent or higher metal include Al ³⁺ , Cr ³⁺ , Fe ³⁺ , and Ni ³⁺ . Among these metals, Al ³⁺ and Cr ³⁺ are preferable, and Al ³⁺ is particularly preferable.

  In the present invention, an aluminum compound of di-tert-butylsalicylic acid is particularly preferable as the charge control agent.

  In the present invention, the charge control agent preferably has a content of 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 0.1 parts by mass, the change in the charge amount of the toner in an environment from high temperature and high humidity to low temperature and low humidity may become large. If the amount is more than 10 parts by mass, the toner may be inferior in low-temperature fixability.

  As the colorant of the color toner used in combination with the black toner, known pigments and dyes can be used alone or in combination. Examples of dyes include the following. C. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modern Tread 30, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modern Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Basic green 6.

  Examples of the magenta coloring pigment used as a full-color image forming toner include the following. C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209, 238, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35.

Although such a pigment may be used alone, it is more preferable from the viewpoint of the image quality of a full-color image to improve the sharpness by using a dye and a pigment together. Examples of the magenta dye include the following. C. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disper thread 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27, C.I. I. Oil-soluble dyes such as Disperse Violet 1;
C. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, C.I. I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

  Examples of the color pigment for cyan include the following. C. I. Pigment blue 2, 3, 15, 16, 17; I. Acid Blue 6; I. A copper phthalocyanine pigment having 1 to 5 phthalimidomethyl groups substituted on Acid Blue 45 or a phthalocyanine skeleton. Particularly preferred is C.I. I. Pigment Blue 15: 3.

  Examples of the color pigment for yellow include the following. C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 83, 93, 97, 155, 180, 185, C.I. I. Bat yellow 1, 3, 20

  The amount of the colorant used in the color toner is preferably 1 to 15 parts by mass, more preferably 3 to 12 parts by mass, and 4 to 10 parts by mass with respect to 100 parts by mass of the binder resin. More preferably. When the content of the colorant is more than 15 parts by mass, the transparency is lowered, and in addition, the reproducibility of intermediate colors as typified by human skin color is likely to be lowered, and further, the chargeability of the toner is stabilized. And the low-temperature fixability becomes difficult to obtain. When the content of the colorant is less than 1 part by mass, the coloring power is low, so that a large amount of toner must be used to obtain the density, the dot reproducibility is easily impaired, and a high-quality image with a high image density. Is difficult to obtain.

  Moreover, the colorant used for the black toner of the present invention can be used in combination with the iron-titanium composite oxide and the known pigments and dyes listed above for adjusting the black hue.

  In the present invention, the black toner preferably has a weight average diameter (D4) of 3.0 to 7.0 μm. While toner of small particle size such as fine line reproducibility of image and coloring power is excellent, problems of reduction of toner diameter such as white background fogging and charge-up during durability are likely to occur due to toner charge distribution control. In particular, when there is non-uniformity of the colorant, a problem is likely to occur in order to make full use of these small particle size toners. In the present invention, it has become possible to solve these problems with small particle diameters and to achieve a clear image.

  The weight average particle diameter of the toner used in the present invention is 3.0 to 7.0 μm as described above. Preferably, it is 4.0 to 6.5 μm. A weight average particle size of less than 3.0 μm is not preferred because current electrophotographic systems are prone to cleaning failures and charge control is difficult. On the other hand, if it exceeds 7.0 μm, the dot reproducibility may decrease as the resolution of the image increases, which is not preferable.

  To the black toner of the present invention, inorganic fine powder is externally added and used for the purpose of improving durability, fluidity, chargeability and transferability. The inorganic fine powder externally added to the surface of the black toner is one of the inorganic fine powders, and at least one of titanium oxide, alumina oxide, and silica. Use of fine particles having a particle size (peak value of the number distribution) of 50 nm or less in combination is preferable for improving toner fluidity. In addition to the inorganic fine powder, when an inorganic fine powder having an average particle diameter (number distribution peak value) of 80 to 200 nm is used in combination, when the black toner of the present invention is used for the two-component developer, the toner is separated from the carrier. It is preferable when functioning as a spacer particle for improving.

  Examples of the magnetic carrier used in the two-component developer of the present invention include, for example, surface oxidized or unoxidized metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth, and their magnetic alloys or magnetic oxidation. And magnetic ferrite.

  Furthermore, a binder-type carrier in which magnetic powder is dispersed in a resin can also be used. In the present invention, it is preferable to use a coated carrier in which the above-described magnetic carrier is used as a carrier core and the surface of the carrier core is coated with a coating material.

  In a coated carrier, the method of coating the surface of the carrier core with a coating material includes a method in which the coating material is dissolved or suspended in a solvent and applied to the carrier core, or a method of simply mixing in a powder state. Applicable.

  Examples of the carrier core coating material include polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, styrene resin, acrylic resin, polyamide, polyvinyl butyral, and aminoacrylate resin. These are used alone or in plural.

  Although the processing amount of the said coating | covering material should just be determined suitably, Preferably it is 0.1-30 mass% with respect to a resin coat carrier, More preferably, 0.5-20 mass% is good.

  The carrier used in the present invention preferably has a 50% volume average particle size of 10 to 80 μm, more preferably 20 to 70 μm.

  When the 50% volume average particle size of the carrier is less than 10 μm, the packing of the two-component developer is strengthened, the mixing property of the toner and the carrier is lowered, the toner chargeability is difficult to be stabilized, and the carrier Adhesion to the surface of the photosensitive drum is likely to occur.

  When the 50% volume average particle size of the carrier exceeds 80 μm, the chance of contact with the toner is reduced, so that low-charge toner is mixed and fogging is likely to occur. Furthermore, since toner scattering tends to occur, it is necessary to lower the toner concentration setting in the two-component developer, and it may be impossible to form an image with a high image density.

  As a method of adjusting the magnetic carrier so as to have the above 50% volume average particle size and a specific particle size distribution, for example, classification by using a sieve can be performed. In particular, in order to classify with high accuracy, it is preferable to repeat several times using a sieve having an appropriate mesh size. It is also effective to use a mesh whose shape is controlled by plating or the like.

As a particularly preferred carrier, the surface of a magnetic core particle such as a magnetic ferrite core particle is coated with a resin coating material such as a silicone resin, a fluorine resin, a styrene resin, an acrylic resin, and a methacrylate resin on the carrier core.
Preferably it is 0.01-5 mass%, More preferably, it is 0.1-1 mass%, contains 70 mass% or more of 250 mesh pass and 400 mesh on carrier particles, and has a 50% volume average particle size. Examples thereof include magnetic carriers having a particle size distribution adjusted to 10 to 80 μm.

  The magnetic carrier and the toner of the present invention can be mixed and used in a form having a specific surface area.

  When a two-component developer is prepared by mixing a toner and a magnetic carrier, for example, when a carrier having a 50% volume average particle size of 40 μm is used, the mixing ratio is 2 to 15 mass as the toner concentration in the developer. %, Preferably 3 to 13% by mass, more preferably 4 to 10% by mass, usually good results are obtained. If the toner concentration is less than 2% by mass, the image density tends to be low, and if it exceeds 15% by mass, fogging or in-machine scattering tends to occur and the useful life of the developer tends to be shortened. When a magnetic carrier having a small particle diameter is used, it is effective to appropriately increase the toner concentration in the developer in order to adjust the specific surface area of the magnetic carrier and the charge amount of the toner.

  The two-component developer toner concentration is preferably about 4% by mass to 12% by mass in consideration of charging amount application, fogging, image density, white spot prevention, and the like.

  When the black toner of the present invention is used in a non-magnetic one-component development system, particularly good characteristics such as durability can be obtained. The following reasons can be considered.

  When the dispersibility of the colorant is improved, the colorant exposed on the toner surface is reduced, and the release of the colorant from the toner can be suppressed. Here, the colorant detached from the toner not only causes image defects by contaminating or scraping the developing member, but can also cause deterioration of the main body. Therefore, in order to improve durability, it is necessary to suppress separation of the colorant.

  The black toner of the present invention can improve the dispersibility of the colorant by combining the type of the colorant, the type and amount of the surface treatment agent, and the binder resin composition. As a result, for example, even when used in a one-component cleanerless system, high-quality images can be obtained over a long period of time.

  Next, the image forming method of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of development, transfer, and fixing processes of a full-color laser beam printer of a non-magnetic contact one-component development system which is an image forming apparatus embodying the present invention.

  In FIG. 1, the process stations 1a, 1b, 1c, and 1d form black, yellow, magenta, and cyan images, respectively. In each process station, image formation is performed as follows.

  The photosensitive drum 2 is uniformly charged by the charging roller 3, and then an information signal is exposed by a light emitting element 4 such as a laser to form an electrostatic latent image, which is visualized by the developing device 5. Next, the visible image is directly transferred to the transfer sheet S by the charge of the opposing transfer roller 14. The toner remaining without being transferred onto the photosensitive drum is removed by the cleaning device 6.

  The transfer paper S on which the four color toner images are laminated is mixed and fixed by heat and pressure in the fixing unit 18 and is discharged out of the apparatus as a full-color image.

  FIG. 2 is a block diagram showing an example of a process station, which includes 30 photosensitive drums, 31 developing elastic rollers, 32 regulating blades, 33 cleaning blades, and 34 charging rollers. The toner T is contained in 35 developing containers.

  On the other hand, for evaluation as a two-component developer, Canon CP2150 was used as an image forming apparatus. Since this machine recycles the untransferred toner on the photosensitive drum, toner with low durability tends to cause deterioration in image quality.

  A suitable method for measuring physical properties related to the present invention will be described below.

<Number average particle diameter (Dp) measurement method of iron-titanium composite oxide and calculation formula of standard deviation σ of particle size>
Using statistical diffraction (Digitizer KD4620, manufactured by Graphtec Co., Ltd.), 350 particles were arbitrarily measured on the particles of the image taken by electron microscope observation, and the number average value (Dp) and standard deviation σ were obtained.

Moreover, it computed according to the following formula from the said number average diameter Dp (micrometer) and the said standard deviation (sigma) (micrometer). The smaller the value of the particle size distribution, the better the particle size distribution.
Coefficient of variation of particles (%) = (σ / Dp) × 100

<Peak intensity of Si and Ti atoms by fluorescent X-ray>
The sample is press-molded using a sample press molding machine (MAEKAWA Testing machine (manufactured by MFG Co., Ltd.). The press applies a pressure of 196000 kPa (2000 kgw / cm ² ) for about 30 seconds to a sample of about 4 g. A measurement piece having a thickness of about 2 mm and a diameter of about 39 mm was produced.

  Next, the Kα peak angles of Si atoms and Ti atoms are obtained from the 2θ table, and the sample is put into a fluorescent X-ray analyzer SYSTEM 3080 (manufactured by Rigaku Corporation), and the X-ray intensity (kcps) of each sample is calculated. Asked. The fluorescent X-ray analysis was performed according to JIS K0119 general X-ray fluorescence analysis rules.

〔Measurement condition〕
Measurement potential, voltage 50kV-50mA
2θ angle a
Crystal plate LiF
Measurement time 60 seconds

<Method for separating colorant from black toner>
3 g of the black toner of the present invention is dissolved in 100 mL of xylene and decanted. This was repeated three times, and the resulting precipitate was dried overnight in a vacuum dryer, and then the colorant was isolated.

<Measurement method of X-ray diffraction of toner>
X-ray diffraction measurement of the black toner of the present invention was performed under the following conditions using CuKα rays.

Measuring instrument used: Rigaku Denki Co., Ltd., fully automatic X-ray diffractometer RINT-TTRII
X-ray tube: Cu
Tube voltage: 50KV
Tube current: 300 mA
Scan mode: continuous scan speed: 4 deg. / Min
Sampling interval: 0.020 deg.
Start angle (2θ): 3 deg.
Stop angle (2θ): 60 deg.
Divergence slit: Open Divergence length restriction slit: 10.00mm
Scattering slit: Open Light receiving slit: Open Using curved monochromator

In the measurement of the diffraction angle and the half-value width of a specific peak, the following items were changed and measured in order to increase the measurement accuracy.
Scan mode: FT mode Counting time: 1.0 sec
Sampling interval: 0.005 deg.
Start angle (2θ): 32 deg.
Stop angle (2θ): 34 deg. 2θ = 32.0-34.0 degree range

<BET specific surface area value of iron-titanium composite oxide>
Using “Mono Sorb MS-II” (manufactured by Yuasa Ionics Co., Ltd.), the BET multipoint method by N2 adsorption is used. As a sample pretreatment, deaeration is performed at 50 ° C. for 10 hours.

<Measurement of toner particle or toner particle size distribution>
As a measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter Inc.) is used. As the electrolytic solution, an about 1% NaCl aqueous solution is used. As the electrolytic solution, an electrolytic solution prepared using primary sodium chloride or, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan) can be used.

  As a measurement method, 0.1 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) is added as a dispersant to 30 ml of the electrolytic solution, and then 2 mg of a measurement sample is added. The electrolyte solution in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser, and the volume and number of the sample are measured for each channel by the measuring device using a 100 μm aperture as the aperture. Volume distribution and number distribution are calculated. From these obtained distributions, the weight average particle diameter of the sample is determined. As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 00 μm; 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32-40.30 μm are used.

<Measurement of magnetization of iron-titanium composite oxide and toner>
The strength of magnetization of the iron-titanium composite oxide and the toner is determined from the magnetic properties and the true density. For the true density, data measured with a dry automatic densimeter “Acpic 1330” manufactured by Shimadzu Corporation was used. The magnetic properties of the colorant and toner can be measured using “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.). As a measuring method, a cylindrical plastic container is filled with a colorant or a toner so as to be sufficiently dense, while an external magnetic field of 10 kilo-Oersted (796 kA / m) is formed, and in this state, the color filled in the container is filled. The magnetization moment of the agent or toner is measured. Further, the actual mass of the colorant or toner filled in the container is measured to determine the magnetization intensity (Am ² / kg) of the colorant or toner.

<Method for measuring acid value>
Samples 2 to 10 g are weighed into a 200 to 300 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of methanol: toluene = 30: 70 is added to dissolve the resin. If solubility is poor, a small amount of acetone may be added. Using a mixed indicator of 0.1% bromthymol blue and phenol red, titration is performed with a pre-standardized N / 10 caustic potash to alcohol solution, and the acid value is obtained from the consumption of the alcohol potash solution by the following calculation.
Acid value = KOH (ml) x N x 56.1 / sample weight (where N is a factor of N / 10 KOH)

<Measurement method of endothermic peak of wax>
It measures according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device) and DSC-7 (manufactured by Birkin Lermer). The measurement sample is precisely weighed in an amount of 2 to 10 mg, preferably 5 mg. This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rise rate of 10 ° C./min at room temperature and normal humidity within a measurement temperature range of 30 to 200 ° C. In this temperature raising process, an endothermic peak of the main peak of the DSC curve in the temperature range of 30 to 200 ° C. is obtained.

  Next, a black toner evaluation method using the image forming apparatus will be described. For the one-component development system, a Canon EP85 cartridge was filled with the toner of the present invention, and a Canon laser beam printer LBP5500 modified machine was used for image output. For the two-component developing system, a developing device of the same machine as Canon CP2150 was used. Both evaluations were performed under normal temperature and normal humidity (23 ° C., 65% Rh). As the paper, plain paper (color laser copier paper TKCLA4; manufactured by Canon) was used. Unless otherwise specified, fixing was performed with a main body fixing device.

<White background fog>
Photosensitive so that the image area density is about 1.4, and the potential difference between the white background potential (VD) and the DC component (VDC) of the developing bias applied to the developing sleeve is 150 V (Vback). The potential on the body was adjusted. Under this condition, a solid white image was formed, the photoconductor was stopped during the image formation, and the toner on the photoconductor before the transfer process was peeled off using Mylar tape and pasted on paper. In addition, the mylar tape was directly pasted on paper as a reference.

Regarding the measurement, DENSOMETER TC-6DS manufactured by Tokyo Denshoku Technical Center was used to measure the reflectance (%), and the difference from the reference was set as the fog value.
A: The difference in reflectance on the photoconductor is 0.5% or less, which is good.
B: The difference in reflectance on the photoconductor is 1.0% or less and cannot be identified as an image.
C: The difference in reflectance on the photoconductor exceeds 1.0%, but it does not appear as an image, and there is no problem in actual use.
D: The difference in reflectance on the photoconductor exceeds 1.0%, and fog is seen on the white background portion of the image.

<Dot reproducibility evaluation method>
On plain paper (color laser copier paper TKCLA4; manufactured by Canon), an image-printing test was performed using the 80 μm × 50 μm checker pattern shown in FIG. 3, and the presence or absence of a black portion was observed with a microscope. It evaluated according to.
A: Not more than 2 defects in 100 dots Very good dot reproducibility.
B: 3 to 5 defects in 100 pieces Good dot reproducibility.
C: 6 to 10 defects in 100 pieces. Acceptable dot reproducibility.
D: 11 or more defects out of 100

<Durability evaluation method>
Durability evaluation was carried out by printing characters at a printing area ratio of 4%, and determining the number of smears due to defective charging on the image and the solid image density by Macbeth at that time. When the smudge did not occur, image printing was continued up to 1000 sheets. It means that the greater the number of smudges, and the higher the image density at that time, the better the durability.
A: Very good with no stains B: 1 to 5 sheets with stains in 1000 sheets, good C: 6 to 10 sheets with stains in 1000 sheets D: No more than 11 sheets with contamination in 1000 sheets

<Fixability evaluation method>
An image was produced so that the applied amount in the case of a solid black image (FFH) was 1.0 mg / cm ² . Next, a halftone image (30H) was produced under this contrast condition, and taken out as an unfixed image without passing through the fixing device. On the other hand, the fixing device of laser jet 4100 (manufactured by Hewlett Packard) was removed, and an external fixing test apparatus capable of controlling the temperature was produced. The above-mentioned unfixed image was fixed on A4 paper while changing the fixing temperature using this apparatus. The obtained fixed image was subjected to cold offset evaluation as to whether or not the image was peeled off by a rubbing test. In the rubbing test, it was judged that the image was peeled off when the image density reduction rate exceeded 10% when rubbing 10 times with Silbon paper at a load of 4.9 kPa. Further, a hot offset evaluation was performed visually to determine whether or not the image of the previous circumference appeared on the white background portion after one round of the fixing device. The paper feed speed of the fixing device was set to 100 mm / s.

A cold offset test was performed to determine whether or not the image was peeled off in the obtained fixed image rubbing test, and a hot offset evaluation was performed to determine whether or not the image of the previous periphery appeared on the white background portion after one cycle of the fixing device.
A: The solid image has a fixable range of 40 ° C. or more, and no offset occurs in the halftone area in this area.
B: The solid image fixing range is 30 to 40 ° C., and no offset occurs in the halftone area in this area.
C: The solid image has a fixable range of 30 to 40 ° C., but an offset occurs in the halftone area in this area.
D: The fixing range is less than 30.

<Image density measurement method>
Regarding the image density, a solid image of 0.6 mg / cm ² was output on plain paper (color laser copier paper TKCLA4; manufactured by Canon) and evaluated using a reflection densitometer 500 Series Spectrodensitometer manufactured by X-rite.
A: Very good 1.50 or more B: Good 1.40 or more and less than 1.50 C: No practical problem 1. 20 or more and less than 1.40 D: Somewhat difficult 1. Less than 1.20

<Measurement method of black hue>
Using the toner and the modified machine, seven steps (0.10 g / cm ² , 0.15 g / cm ² , 0.20 g / cm ² , 0.25 g / cm2) on paper (color laser copier paper TKCLA4, manufactured by Canon) cm ² , 0.30 g / cm ² , 0.35 g / cm ² , and 0.40 g / cm ² ) to form a fixed image, and for each fixed image, use Spectroscan and SpectroLino manufactured by Gretag Macbeth. Used (measuring condition: D65, viewing angle 2 degrees), CIE a ^* and b ^* values were measured. Plot the chromaticity against the 7 loadings, draw a curve that smoothly connects each point, and calculate the value C ^* that maximizes the distance from the origin (a ^* = 0, b ^* = 0) on the curve. Asked. The evaluation criteria are as follows.
A: C ^{* The} maximum value is within 5.
B: C ^{* The} maximum value is within 10.
C: C ^{* The} maximum value exceeds 10.

C ^* is determined by C ^* = ((a ^* ) ² + (b ^* ) ² ) ^1/2 .

(Production Example 1 of Black Colorant)
17.8 L of a 1.8 mol / L ferrous sulfate aqueous solution was added to 22.2 L of a 2.76 N NaOH solution to obtain a reaction solution containing a total amount of 40 L and a pH 6.5 iron hydroxide colloid. Thereafter, the temperature of the reaction solution was raised to 90 ° C., air was passed through for 100 minutes, and 18 L of a 0.48 mol / L titanyl sulfate aqueous solution was added to form a black precipitate. During this time, the temperature was maintained at 90 ° C. and pH 6.5.

The black precipitate was filtered off, washed with water, dried at 60 ° C., and further heated and fired at 730 ° C. for 60 minutes under a N ₂ gas flow, and then pulverized to obtain a fired pigment 1 which was an iron-titanium composite oxide. . The constituent phase of the calcined pigment 1 was a FeTiO ₃ —Fe ₂ O ₃ solid solution.

100 parts by mass of the calcined pigment 1 Silane coupling agent A (3-glycidoxypropyltrimethoxysilane)
0.40 parts by mass

Water 300 parts by mass Methanol 50 parts by mass The pH of the above mixture was adjusted to 8.5 and sufficiently stirred. The produced black colorant was washed and dried to obtain black colorant 1. The pH of the aqueous solution is preferably 7 to 10 because the silane coupling agent is likely to be cyclized by intramolecular hydrogen bonding at low pH, and the interaction with the resin is weakened at high pH.

The resulting black colorant 1 has a number average particle size (Dp) of 0.19 μm, a standard deviation σ of 0.073 μm, (σ / Dp) of 38.4%, and a BET specific surface area value of 9.9 m ² / g. The magnetization value (σs) at an external magnetic field of 796 kA / m was 3.5 Am ² / kg.

(Production Examples of Black Colorant-2 to 3, 11, 12)
Except for changing the addition amount of the silane coupling agent A to 0.60, 0.30, 0.15, and 1.2 parts by mass, respectively, the same method as in Production Example-1 of the production example of the black colorant, Black colorant 2, black colorant 3, black colorant 11, and black colorant 12 were obtained.

(Production Example 4 for Black Colorant)
Silane coupling agent B (3-carboxypropyltriethoxysilane) instead of silane coupling agent A

を０．４２質量部用いた以外は、黒色着色剤の製造例の製造例−１と同じ方法で、黒色着色剤４を得た。

The black colorant 4 was obtained by the same method as the manufacture example-1 of the manufacture example of a black colorant except having used 0.42 mass part.

(Production Example of Black Colorant-5)
Instead of silane coupling agent A, silane coupling agent C (3-aminopropyltrimethoxysilane)

を０．３０質量部用いた以外は、黒色着色剤の製造例の製造例−１と同じ方法で、黒色着色剤５を得た。

The black colorant 5 was obtained by the same method as the manufacture example-1 of the manufacture example of a black colorant except having used 0.30 mass part.

(Production Example of Black Colorant-6)
Silane coupling agent D (3-methacryloxypropyltrimethoxysilane) instead of silane coupling agent A

を０．４２質量部用いた以外は、黒色着色剤の製造例の製造例−１と同じ方法で、黒色着色剤６を得た。

The black coloring agent 6 was obtained by the same method as the manufacture example-1 of the manufacture example of a black coloring agent except having used 0.42 mass part.

(Production Example of Black Colorant-7)
Silane coupling agent E (3-acryloxypropyltrimethoxysilane) instead of silane coupling agent A

を０．３０質量部用いた以外は、黒色着色剤の製造例の製造例−１と同じ方法で、黒色着色剤７を得た。

The black colorant 7 was obtained by the same method as the manufacture example-1 of the manufacture example of a black colorant except having used 0.30 mass part.

(Production Example of Black Colorant-8)
Baked Pigment 1 100 parts by weight Silicone oil a having a glycidyl group in the side chain and represented by the following structural formula (number average degree of polymerization n = 4) 1.50 parts by weight are mixed and sufficiently stirred to obtain a black colorant. 8 was obtained.

(Production Example of Black Colorant-9)
Silane coupling agent F (3-glycidoxypropyltriethoxysilane) instead of silane coupling agent A

を０．４５質量部用いた以外は、黒色着色剤の製造例の製造例−１と同じ方法で、黒色着色剤９を得た。

The black colorant 9 was obtained by the same method as the manufacture example-1 of the manufacture example of a black colorant except having used 0.45 mass part.

(Production Example of Black Colorant-10)
To an aqueous suspension containing 10 kg of spherical magnetite particle powder, an aqueous solution containing 43.6 mol of titanyl sulfate (corresponding to 30 atomic% in terms of Ti with respect to the total Fe of the magnetite particle powder) is added. In addition, NaOH was added to the mixed solution so that the pH of the reaction solution was maintained at 8.5 or higher during the addition. Next, after adjusting the pH of the mixed solution to 8.0 and depositing the hydrous titanium oxide on the surface of the magnetite particles, the titanium oxide is coated with titanium hydrous oxide by filtration, washing and drying. A spherical black magnetic iron oxide particle powder was obtained.

1 kg of spherical black magnetic iron oxide particle powder having the particle surface coated with a hydrous oxide of titanium was heated and calcined at 790 ° C. for 120 minutes under a N ₂ gas flow, and then pulverized to obtain calcined pigment 2.

100 parts by mass of the calcined pigment 2 Silane coupling agent A (3-glycidoxypropyltrimethoxysilane)
0.40 parts by mass Water 800 parts by mass The pH of the above mixture was adjusted to 6 and sufficiently stirred. The generated black colorant was washed and dried to obtain a black colorant 10.

(Production Example of Black Coloring Agent-13)
Spherical magnetite (fired pigment 3) 100 parts by weight (number average particle size 0.21 μm, BET specific surface area 12.5 m ² / g, magnetization value (σs) at an external magnetic field of 796 kA / m is 21 A m ² / kg) A black colorant 13 was obtained in the same manner as in Production Example-1 of black colorant except that it was used instead of 1.

(Production Example of Black Colorant-14)
The calcined pigment 2 was used as it was to obtain a black colorant 14.

(Production Example of Black Colorant-15)
17.8 L of a 1.8 mol / L ferrous sulfate aqueous solution was added to 22.2 L of a 2.76 N NaOH solution to obtain a reaction solution containing a total amount of 40 L and a pH 6.5 iron hydroxide colloid. Thereafter, the temperature of the reaction solution was raised to 85 ° C., air was passed through for 200 minutes, and 18 L of a 0.48 mol / L aqueous solution of titanyl sulfate was added to form a black precipitate. During this time, the temperature was maintained at 85 ° C. and pH 6.0.

The black precipitate was separated by filtration, washed with water, dried at 60 ° C., and 4.2 g of sodium sulfate was added to and mixed with 100 g of the black precipitate. Next, the obtained mixture was heated and calcined at 730 ° C. for 60 minutes under a N ₂ gas flow, and then pulverized to obtain a sodium-containing iron-titanium composite oxide (calcined pigment 4).

Baked pigment 4 100 parts by mass Silane coupling agent A 0.40 parts by mass Water 300 parts by mass Methanol 50 parts by mass The pH of the above mixture was adjusted to 8.5 and sufficiently stirred. The produced colorant was washed and dried to obtain a black colorant 15. At this time, the pH of the aqueous solution is preferably 7 to 10.

The resulting black colorant 15 has a number average particle size (Dp) of 0.22 μm, a standard deviation σ of 0.057 μm, (σ / Dp) of 25.9%, and a BET specific surface area value of 10.3 m ² / g. The magnetization value (σs) at an external magnetic field of 796 kA / m was 0.30 Am ² / kg.

(Production Example of Black Colorant-16)
17.8 L of a 1.8 mol / L ferrous sulfate aqueous solution was added to 22.2 L of a 2.76 N NaOH solution to obtain a reaction solution containing a total amount of 40 L and a pH 6.5 iron hydroxide colloid. Thereafter, the temperature of the reaction solution was raised to 90 ° C., air was passed through for 100 minutes, and 20 L of a 0.48 mol / L aqueous solution of titanyl sulfate was added to form a black precipitate. Thereafter, a NaOH solution was added, and the temperature was maintained at 90 ° C. and pH 12.0.

The black precipitate was separated by filtration, washed with water, dried at 60 ° C., and 4.2 g of sodium sulfate was added to and mixed with 100 g of the black precipitate. Next, the obtained mixture was heated and fired at 810 ° C. for 60 minutes under a N ₂ gas flow, and then pulverized to obtain a sodium-containing iron-titanium composite oxide (fired pigment 5). The constituent phase of the calcined pigment 5 was a mixture of a FeTiO ₃ —Fe ₂ O ₃ solid solution and NaFeTi ₃ O ₈ .

Baked pigment 5 100 parts by mass Silane coupling agent A 0.40 parts by mass Water 300 parts by mass Methanol 50 parts by mass The pH of the above mixture was adjusted to 8.5 and sufficiently stirred. The produced colorant was washed and dried to obtain a black colorant 16. At this time, the pH of the aqueous solution is preferably 7 to 10.

The resulting black colorant 16 has a number average particle diameter (Dp) of 0.23 μm, a standard deviation σ of 0.069 μm, (σ / Dp) of 30.0%, and a BET specific surface area value of 6.9 m ² / g. The magnetization value (σs) at an external magnetic field of 796 kA / m was 1.0 Am ² / kg.

The reason why NaFeTi ₃ O ₈ was detected in the black colorant 16 is thought to be that the pH was set high by adding an NaOH solution before filtering the black precipitate.

(Method for producing hybrid resin-1)
As a vinyl copolymer,
1.9 mol of styrene,
0.21 mol of 2-ethylhexyl acrylate,
Fumaric acid 0.15 mol,
α-methylstyrene dimer 0.03 mol,
Dicumyl peroxide 0.05 mol
In a dropping funnel. Also,
7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane,
3.0 mol of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane,
Succinic acid 3.0 mol,
Trimellitic anhydride 2.0 mol,
Fumaric acid 5.0 mol
In addition, 0.2 g of dibutyltin oxide was placed in a 4-liter four-necked flask made of glass, and a thermometer, a stirring rod, a condenser and a nitrogen introducing tube were attached and placed in a mantle heater. Next, after the inside of the flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and the mixture of the vinyl resin monomer, the crosslinking agent and the polymerization initiator was added from the previous dropping funnel while stirring at a temperature of 145 ° C. Was added dropwise over 4 hours. Subsequently, the temperature was raised to 200 ° C. and reacted for 5 hours to obtain a hybrid resin A. The acid value of the hybrid resin A was 29 mgKOH / g.

(Polyester resin production example 1)
3.6 mol of polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane,
Polyoxyethylene (2.2) -2, 1.4 mol of 2-bis (4-hydroxyphenyl) propane,
Terephthalic acid 3.0 mol,
Trimellitic anhydride 0.2 mol,
1.7 mol of fumaric acid
Then, 0.1 g of dibutyltin oxide was placed in a 4-liter four-necked flask made of glass, and a thermometer, a stirring rod, a condenser and a nitrogen introduction tube were attached and placed in a mantle heater. The polyester resin A was obtained by reacting at 220 ° C. for 4 hours under a nitrogen atmosphere. The acid value of the polyester resin A was 36 mgKOH / g.

(Polyester resin production example 2)
1.6 mol of polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane,
Polyoxyethylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane 3.4 mol,
Terephthalic acid 2.0 mol,
Trimellitic anhydride 0.3 mol,
2.7 mol of fumaric acid
Was reacted in the same manner as in Polyester Resin Production Example 1 to obtain a polyester resin B. The acid value of the polyester resin B was 20 mgKOH / g.

(Vinyl resin production example 1)
2.0 mol of styrene, 0.24 mol of butyl acrylate, 0.16 mol of fumaric acid, 0.04 mol of dimer of α-methylstyrene, and 0.05 mol of dicumyl peroxide were placed in a dropping funnel. Moreover, 7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxy) are used as materials for the polyester unit. (Phenyl) propane (3.0 mol), terephthalic acid (3.0 mol), trimellitic anhydride (2.0 mol), fumaric acid (5.0 mol) and dibutyltin oxide (0.2 g) were put into a reaction vessel, and a thermometer, a stirring rod, a condenser, and nitrogen were introduced. A tube was attached to the reaction vessel, and the inside of the reaction vessel was replaced with nitrogen gas. While stirring, the temperature was gradually raised, and while stirring at a temperature of 15 ° C., the monomer of the vinyl copolymer, the crosslinking agent and the polymerization initiator were added dropwise from the previous dropping funnel over 5 hours. Next, the temperature was raised to 200 ° C. and reacted for 4 hours to obtain a vinyl resin A. The obtained vinyl resin A had an acid value of 15 mgKOH / g and Tg of 61 ° C.

<Example 1>
Black toner 1 was prepared by the following method.

Polyester resin A 100 parts by mass Black pigment 1 30 parts by mass Wax A (endothermic peak temperature by paraffin wax DSC 72 ° C) 3 parts by mass Aluminum compound of di-tert-butylsalicylic acid (charge control agent) 0.5 Part by mass The material of the above formulation was mixed well with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), and then a twin-screw kneader (PCM-45 type, Ikegai Iron Works ( Kneading). The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely pulverized toner was pulverized using a collision-type airflow pulverizer using high-pressure gas. The obtained finely pulverized product had a weight average diameter of 4.8 μm. Next, fine powder and coarse powder were simultaneously removed from the obtained finely pulverized product by a multi-division classifier utilizing the Coanda effect, whereby black toner particles 1 were obtained.

  To 100 parts by mass of the obtained black toner particles 1, 0.5 parts by mass of hydrophobized titanium oxide having an average particle diameter of 40 nm and 1.5 parts by mass of amorphous silica having an average particle diameter of 110 nm were externally mixed. A black toner 1 was obtained. The obtained black toner 1 had a weight average particle diameter (D4) of 5.6 μm and a number average particle diameter (Dp) of 4.8 μm. Table 3 shows the characteristics of the black toner 1.

  For non-magnetic contact one-component development, a modified model of Canon full color laser beam printer LBP-5500 is used, and for two-component development, Canon CP2150 is used to evaluate various characteristics of black toner 1 in electrophotography. It was. The evaluation results are shown in Table 4, respectively.

<Examples 2-14, Comparative Examples 1-8>
The black toners 2 to 23 used in Examples 2 to 14 and Comparative Examples 1 to 8 were produced under the same conditions as in Example 1. However, the materials shown in Table 2 were used. Subsequently, each was evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4, respectively. Wax B is a paraffin wax having an endothermic peak temperature of 85 ° C. by DSC.

<Example 15>
A cyan toner was prepared by the following method.

(First kneading step)
-60 parts by weight of polyester resin A-First paste pigment with a solid content of 40% by weight obtained by removing water from the pigment slurry to some extent from the filtration step of Cu phthalocyanine and without passing through the drying step (remaining amount) 100 mass parts of the above raw materials are first charged in a kneader-type mixer with the above formulation, and heated under non-pressurization while mixing. When the maximum temperature (necessarily determined by the boiling point of the solvent in the paste. In this case, about 90 to 100 ° C.) is reached, the pigment in the aqueous phase is distributed or transferred to the molten resin phase, and this is confirmed. After that, the mixture is further melted and kneaded for 30 minutes to sufficiently transfer the pigment in the paste. Then, once the mixer was stopped and hot water was discharged, the temperature was further raised to 130 ° C., heated and melted and kneaded for about 30 minutes, the pigment was dispersed and the water was distilled off, and the process was completed. The kneaded product was taken out and cooled to obtain a first kneaded product. The water content of the first kneaded product was about 0.5% by mass.

(Second kneading step)
Polyester resin A 92.5 parts by mass The first kneaded product (pigment particle content 40% by mass) 12.5 parts by mass Wax A (endothermic peak Tg = 68 ° C. by paraffin DSC) 4 parts by mass -Aluminum compound of tert-butylsalicylic acid (charge control agent) 0.5 part by mass The material of the above formulation was mixed well with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), and then the temperature was 130 ° C. Kneading with a twin-screw kneader (PCM-30 type, manufactured by Ikekai Tekko Co., Ltd.) The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The resulting coarsely pulverized toner was pulverized using a collision-type airflow pulverizer using high-pressure gas in the same manner as in Example 1, and fine powder and coarse powder were simultaneously and strictly removed with a multi-division classifier to obtain cyan toner particles 1 Got.

  To 100 parts by mass of the obtained cyan toner particles 1, 1.0 part by mass of titanium oxide having an average particle diameter of 40 nm hydrophobized and 1.5 parts by mass of amorphous silica having an average particle diameter of 110 nm are externally mixed. Cyan toner 1 was obtained. The obtained cyan toner 1 had a weight average particle diameter of 5.5 μm.

  A developer was prepared by mixing 92 parts by mass of magnetic carrier 1 with 8 parts by mass of the cyan toner using a tumbler mixer.

  Next, instead of Cu phthalocyanine (C.I. Pigment Blue 15: 3), C.I. I. Pigment Yellow 74, C.I. I. Pigment Red 122 was added so as to have the content shown in Table 2. After that, yellow toner 1 and magenta toner 1 were prepared in the same manner as in Example Cyan 1. Further, using the black toner 1 produced in Example 1, four color developers were prepared.

  After that, when full-color image evaluation was performed with the two evaluation machines used in Example 1, a clear and full-color image without image defects was obtained.

<Example 16>
A black toner was prepared in the same manner as in Example 1 except that 30 parts by mass of black colorant 15 was used instead of 30 parts by mass of black colorant 1 in Example 1, and black toner 24 was obtained.

  Subsequently, the same evaluation as in Example 1 was performed. The results are shown in Table 3 and Table 4. The image density of the black toner 24 was higher than the image density of the black toner 1.

<Example 17>
In Example 1, a black toner was prepared in the same manner as in Example 1 except that 30 parts by mass of the black colorant 1 was used instead of 30 parts by mass of the black colorant 1, and a black toner 25 was obtained.

  Subsequently, the same evaluation as in Example 1 was performed. The results are shown in Table 3 and Table 4. The image density of the black toner 25 was higher than the image density of the black toner 1.

1 is a schematic configuration diagram of a full-color image forming apparatus. It is explanatory drawing of the process station of a full-color image forming apparatus. It is explanatory drawing of the checker pattern used for dot reproducibility evaluation.

Explanation of symbols

S ... paper 1 ... process station 2 ... photosensitive drum 3 ... charge roller 4 ... exposure device 5 ... developing means 6 ... cleaning device 7 ... transfer conveyor belt 8 ... driving roller 9 ... driven roller 10 ... belt stretching roller 11 ... belt Stretching roller 12 ... Adsorption roller 13 ... Constant current power supply 14 ... Transfer roller 15 ... Feeding section 16 ... Feeding roller 17 ... Registration roller pair 18 ... Fixing device 19 ... Discharge tray 20 ... Reconveying path 21 ... Reconveying roller

Claims (16)

In a black toner having black toner particles containing at least a binder resin and a colorant and at least one kind of inorganic fine powder,
The black toner has a magnetization value (σs) of 2.0 Am ² / kg or less at an external magnetic field of 796 kA / m,
The binder resin includes (a) a polyester resin, (b) a hybrid resin component having a polyester unit and a vinyl polymer unit, or (c) a mixture thereof.
The colorant comprises an iron-titanium composite oxide, contains a compound selected from a silane coupling agent and silicone oil, and contains 20 to 70 parts by mass with respect to 100 parts by mass of the binder resin.
The black toner particles, wherein the black toner particles have an intensity ratio of Si to Ti in a fluorescent X-ray measurement in a range of 2.0 to 5.0%.   The surface of the colorant is covered with a silane coupling agent having a polar group selected from an epoxy group, a carboxyl group, an amino group, a methacryloxy group, and an acryloxy group, or silicone oil. Black toner. The black toner according to claim 1, wherein the colorant uses any one of compounds having the following structures.

4. The black toner according to claim 1, wherein a water vapor adsorption amount when the relative pressure of the colorant is 0.5 is 0.4 to 0.6 mg / m ² . The black toner according to claim 1, wherein the colorant contains a FeTiO ₃ —Fe ₂ O ₃ solid solution as a main component. 6. The black toner according to claim 1, wherein the colorant contains FeTiO ₃ —Fe ₂ O ₃ solid solution and NaFeTi ₃ O ₈ .   The number average particle diameter of the colorant is 0.1 to 0.3 μm, and the standard deviation σ of the particle diameter of the colorant / number average particle diameter is 45% or less. The black toner according to any one of the above.   The black toner according to claim 1, wherein the colorant contains an iron-titanium composite oxide and is contained in an amount of 25 to 60 parts by mass with respect to 100 parts by mass of the binder resin.   9. The black toner according to claim 1, wherein the binder resin has an acid value of 15 to 40 mg KOH / g. The black toner according to claim 1, wherein the black toner has a dielectric loss ratio (tan δ) at 10 ⁵ Hz of 0.010 or less. 11. The black toner according to claim 1, wherein a magnetization value (σs) of the toner at an external magnetic field of 796 kA / m is 1.5 Am ² / kg or less.   The black toner contains a release agent, and the release agent has an endothermic peak at 60 to 90 ° C. in an endothermic curve in differential thermal analysis (DSC) measurement. Black toner according to crab.   The black toner contains an organometallic compound, and the organometallic compound is an aromatic carboxylic acid derivative selected from an aromatic oxycarboxylic acid and an aromatic alkoxycarboxylic acid, or a metal compound of the aromatic carboxylic acid derivative. The black toner according to claim 1, wherein the toner is a black toner.   14. The black toner according to claim 1, wherein the black toner has a weight average diameter (D4) of 3.0 to 7.0 μm.   The black toner according to claim 1, wherein the black toner is used in a developing device of a non-magnetic one-component developing system.   16. The black toner according to claim 1, wherein the black toner is used in a cleanerless type electrophotographic apparatus.

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