JP2014029512A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic toner capable of suppressing a phenomenon of 'ghost' in which image density decreases on the second turn of a developing sleeve, and suppressing a phenomenon of 'void' in which the whole image drops, even in a high temperature and high humidity environment for a long period of time.SOLUTION: The magnetic toner comprises magnetic toner particles containing a binder resin and a magnetic material, and inorganic fine particles. The inorganic fine particles are silica fine particles. When apparent density and true density of the magnetic toner are denoted by B and A, respectively, and tapping density measured by tapping the toner 30 times after the apparent density is measured is denoted by P, B/A is 0.39 or more and 0.47 or less and an initial density change rate is 14.0 or more and 18.0 or less. A value of [total energy quantity (mJ)/toner density (g/ml)] of the magnetic toner measured by a powder fluidity measuring device including a rotary propeller blade is 200 or more and 300 or less.

Description

  The present invention relates to a toner used in electrophotography, electrostatic recording, magnetic recording, and the like.

In copiers and printers, the lifespan of the devices has been reduced along with the miniaturization of the devices. In view of these points, an advantageous one-component development system is preferably used.
From the viewpoint of downsizing the apparatus, it is important to reduce the volume of each member. In the one-component development method, toner is transported to a development region using a toner carrier (hereinafter also referred to as a development sleeve) and developed. In addition, charge application to the toner is performed mainly by frictional charging by rubbing between the toner and a frictional charge applying member such as a developing sleeve in a region where the toner is regulated by a toner regulating member (hereinafter also referred to as a developing blade). . Particularly in terms of downsizing the apparatus, it is an important technique to reduce the diameter of the developing sleeve.
From the standpoint of extending the service life, it is important to increase the toner filling amount and reduce the toner consumption per printed sheet. It is necessary to create a technology that can obtain sufficient image quality even with the used toner.
It has been found that various technical problems arise when combined with the reduction in the diameter of the developing sleeve described above. One of them is the problem of “white spots” in which the development efficiency is remarkably lowered in the second half of durable use in a high temperature and high humidity environment, and the density of the second round of the developing sleeve is lowered, and “negative ghosts” in which the density of the developing sleeve is reduced There is. (Hereafter, they are called “white spots” and “ghosts”)
The white spots and ghosts cause the toner flow to drop when the toner deteriorates, and the toner is replaced in an area where the entire toner is circulated and the developing blade is rubbed (hereinafter referred to as the blade nip). This is because it is not performed properly. In the magnetic one-component developing system, toner is attracted to the developing sleeve and conveyed by a magnetic roller included in the developing sleeve. In particular, when the diameter of the developing sleeve is reduced in the magnetic one-component development method, the magnetic force is also reduced because the magnetic roller needs to be reduced in size. For this reason, the force for attracting and conveying the toner is weakened, and the circulation of the toner in the toner cartridge (CRG) is deteriorated. In addition, in order to properly frictionally charge the entire toner, toner circulation in the blade nip is required such that the toner in contact with the developing sleeve or the developing blade in the blade nip is replaced with the toner not in contact. . However, the deteriorated toner has poor circulation and the fluidity of the toner is lowered. For this reason, toner replacement is less likely to occur in the blade nip, and charged toner is generated when the same toner is repeatedly rubbed. For this reason, in the second half of the endurance use, the charged-up toner increases in the second and subsequent cycles from the first cycle of the developing sleeve, thereby generating a “ghost” in which the density varies. Further, as the toner proceeds to the latter half of the endurance use, the amount of toner charged up increases, resulting in a decrease in development efficiency and “white spots” that the entire image is missing.
Many studies have been made so far to improve toner fluidity.
In Patent Document 1, two types of silica having different hydrophobicities are externally added, and mention is made of the effect on image defects in a high temperature and high humidity environment.
Patent Document 2 mentions an effect on developability in a high-temperature and high-humidity environment by externally adding highly hydrophobic silica fine particles.
On the other hand, many studies have been made to attach external additives other than silica to toner particles.
Patent Document 3 proposes a technique that can withstand long-term use by adding resin particles having a large particle size other than silica and improving fluidity.
However, it is expected that the above-described ghost and white spot problems will become more severe as the device becomes smaller and has a longer life, and may be a problem in the future. With such a background, even with the conventional technology, the problem cannot be solved and there is still room for improvement.

JP 2009-229785 A JP 2008-151893 A Japanese Patent Application No. 2009-517934

An object of the present invention is to provide a magnetic toner capable of solving the above problems.
Specifically, a magnetic toner that can suppress “ghost” in which the image density of the second round of the developing sleeve decreases and “white spot” in which the entire image is lost over a long period of time even in a high-temperature and high-humidity environment. It is to provide.

The present inventors have found that the problem can be solved by defining the apparent density of the magnetic toner, the density change rate of the magnetic toner in the tap test, and the ease of loosening from the compacted state of the magnetic toner. Completed. That is, the present invention is as follows.
A magnetic toner containing magnetic toner particles containing a binder resin and a magnetic material, and inorganic fine particles,
The inorganic fine particles are silica fine particles;
The apparent density of the magnetic toner is B (g / cm ³ ), the true density is A (g / cm ³ ), and the tap density measured by tapping 30 times from the state where the apparent density is measured is P (g / cm ³ ), B / A is 0.39 or more and 0.47 or less,
The initial density change rate obtained from the following formula (1) is 14.0 or more and 18.0 or less,
The [total energy amount (mJ) / toner density (g / ml)] of the magnetic toner measured by a powder fluidity measuring apparatus equipped with a rotary propeller blade is 200 mJ / (g / ml). The magnetic toner is 300 mJ / (g / ml) or less.
(Formula 1) Initial density change rate = {1- (B / P)} × 100

  According to the present invention, there is provided a magnetic toner capable of suppressing “ghost” in which the image density of the second round of the developing sleeve is lowered and “white-out” in which the entire image is lost over a long period of time even in a high temperature and high humidity environment. can do.

The figure which shows an example of an image forming apparatus Diagram showing the boundary of the diffusion index The figure which plotted the coverage X1 and diffusion index of the toner used for the Example and the comparative example Schematic diagram showing an example of a mixing treatment apparatus that can be used for external addition mixing of inorganic fine particles The schematic diagram which shows an example of a structure of the stirring member used for a mixing processing apparatus Schematic diagram showing the configuration of a stirring member used for evaluation of total energy Explanatory drawing of pattern for evaluating negative ghost

The present invention is as follows.
A magnetic toner containing magnetic toner particles containing a binder resin and a magnetic material, and inorganic fine particles,
The inorganic fine particles are silica fine particles;
The apparent density of the magnetic toner is B (g / cm ³ ), the true density is A (g / cm ³ ), and the tap density measured by tapping 30 times from the state where the apparent density is measured is P (g / cm ³ ), B / A is 0.39 or more and 0.47 or less,
The initial density change rate obtained from the following formula (1) is 14.0 or more and 18.0 or less,
The [total energy amount (mJ) / toner density (g / ml)] of the magnetic toner measured by a powder fluidity measuring apparatus equipped with a rotary propeller blade is 200 mJ / (g / ml). The magnetic toner is 300 mJ / (g / ml) or less.
(Formula 1) Initial density change rate = {1- (B / P)} × 100

According to the study by the present inventors, by using the magnetic toner as described above (hereinafter also simply referred to as toner), the image density on the second circumference of the developing sleeve can be maintained over a long period even in a high temperature and high humidity environment. It is possible to suppress “ghost” that decreases and “white spots” that the entire image is missing.
Here, it is considered that “ghost” and “white spot” occurring in a high temperature and high humidity environment are caused by the following causes.
As the toner is used in a high-temperature, high-humidity environment, the toner is subjected to friction at the blade nip and stress by other members, so that the external additive of the toner is embedded and the toner deteriorates, and sufficient fluidity can be secured. Disappear. If the durable use is continued in this state, it becomes difficult for the toner to be replaced at the blade nip, so that the same toner is repeatedly rubbed by the developing blade, and a charged toner is generated. If development is performed in such a state, the development efficiency is remarkably lowered, and “white spots” are generated in which the entire image is missing. Further, when the toner filling amount is increased and the number of printed sheets is increased (long life), the deterioration of the toner becomes severe.
On the other hand, when the diameter of the developing sleeve is reduced, the magnetic roller included in the developing sleeve also needs to be reduced in diameter, so that the magnetic force is weakened and toner circulation in the toner cartridge (CRG) is deteriorated. In the CRG in which the toner circulation is deteriorated, the toner heated by the frictional heat in the vicinity of the blade nip collides with the toner in other places, and an aggregate of toner is formed at the blade nip entrance. Since the toner agglomerates are formed at the blade nip entrance, toner replacement in the blade nip is further suppressed. From the above, in the second half of the endurance use, the same toner is repeatedly rubbed at the blade nip, and charged toner is generated. As the charged-up toner accumulates, the development efficiency is remarkably lowered, and “white spots” occur in the second half of the endurance use. In addition, as a phenomenon before the “white spot” occurs, if the charged toner accumulates in the blade nip, the replacement of the toner on the developing sleeve is reduced. The amount of applied toner decreases. For this reason, a “ghost” in which a density difference occurs between the first and second rounds of the developing sleeve is generated.

The present inventors consider that the following points are important in order to suppress the “ghost” and “white spot” in the latter half of the durable use.
(1) The external additive is difficult to be embedded in the toner particles even if the durable use is promoted. (Suppression of toner deterioration)
(2) Even when the toner is deteriorated, the toner is replaced in the blade nip.
In particular, in order to solve (2), the following three points are important.
(2-1) Toner Circulation This indicates the toner circulation due to the magnetic force of the magnetic roller.
(2-2) Ease of supplying toner This indicates that the toner is likely to change from the fluidized state to the compacted state at the blade nip.
(2-3) Ease of toner loosening from the compacted state This indicates the ease of toner loosening from the compacted state at the blade nip, and indicates that the chargeability of the toner is maintained by the developing blade.
By solving these problems simultaneously, the present inventors have found that ghosts and white spots can be suppressed over a long period of time even in a high temperature and high humidity environment. In particular, a correlation has been found between “apparent density / true density, initial density change rate, and total energy (to be abbreviated as TE)”, which will be described later, and “replacement of toner at the blade nip”. It came to.

Below, the detail of the form of this invention is demonstrated.
The magnetic toner of the present invention defines toner circulation and toner replacement at the blade nip as follows.
The magnetic toner of the present invention contains magnetic toner particles and inorganic fine particles, the inorganic fine particles are silica fine particles, the apparent density of the magnetic toner is B (g / cm ³ ), and the true density is A (g / Cm ³ ), the ratio of B to A [B / A] is 0.39 or more and 0.47 or less, preferably 0.41 or more and 0.45 or less.
By controlling B / A within the above-mentioned range, the apparent density of the toner when the toner is loosened from the compacted state is smaller than the true density of the toner, and the circulatory property of the toner can be controlled within the range required by the present invention. . A toner having a small B / A indicates that when the toner is loosened from the compacted state, the toner is loosened up to one toner particle, and the toner bites into the air to increase the volume. Since the toner entrained with air can reduce the contact with the adjacent toner, the adhesion force acting between the toners can be reduced. Thereby, even when the toner deteriorates in a high-temperature and high-humidity environment, the circulation property of the toner can be improved.
The apparent density of the toner can be controlled within the above range by adjusting the amount and type of silica fine particles contained in the toner, the particle diameter and the circularity of the toner particles, and may be achieved by any method. When B / A is 0.39 or more and 0.47 or less, the toner circulation is high, so that the toner is circulated by the magnetic force of the magnetic roller even in a high-temperature and high-humidity environment where the remaining amount of toner is small. Toner is also supplied near the blade nip.
That is, the effect (2-1) can be obtained. In particular, when a small-diameter developing sleeve is mounted, the magnetic force of the magnetic roller is reduced, thereby deteriorating toner circulation. Even under such conditions, the effects of the present invention can be obtained by controlling B / A within the scope of the present invention.
When B / A is larger than 0.47, the apparent density of the toner is relatively larger than the true density of the toner. In order to make B / A larger than 0.47, the toner density is increased by using toner particles having a greater degree of circularity of the toner particles, or the true density of the toner is decreased by reducing the amount of magnetic material. There is a need. However, when the apparent density is increased by increasing the circularity of the toner particles, the filling rate of the toner particles is increased and the toner is easily packed, so that the circulation of the toner is weakened, and the effect of (2-1) is achieved. Can not demonstrate. Further, when the amount of the magnetic material is greatly reduced, the toner circulation by the magnetic force of the magnetic roller is weakened, so that the effect (2-1) cannot be exhibited. As a result, toner is not supplied to the vicinity of the blade nip in the second half of durable use in a high-temperature and high-humidity environment, resulting in ghost and white spots.
On the other hand, when B / A is smaller than 0.39, the apparent density of the toner becomes relatively smaller than the true density of the toner. In order to make B / A smaller than 0.39, it is possible to reduce the apparent density of the toner by decreasing the circularity of the toner particles or the particle size of the silica fine particles, or increase the amount of the magnetic material. It is necessary to increase the true density. However, when the apparent density is reduced by reducing the particle size of the silica fine particles or the circularity of the toner particles, the contact area between the toners increases, the adhesion between the toners increases, and the toner circulation property decreases. , (
The effect of 2-1) cannot be exhibited. Further, when the true density is increased by increasing the amount of magnetic material, the weight per toner particle is increased, so that the circulation property of the toner is lowered and the effect (2-1) cannot be exhibited. As a result, the toner is not supplied to the vicinity of the blade nip in the second half of durable use in a high temperature and high humidity environment, resulting in ghosting and white spots.

In the magnetic toner of the present invention, when the tap density measured by tapping 30 times from the state in which the apparent density of the toner is measured is P (g / cm ³ ), the initial density change obtained from the following formula (1) The rate is 14.0 or more and 18.0 or less, preferably 15.0 or more and 17.0 or less.
(Formula 1) Initial density change rate = (1−B / P) × 100
By controlling the initial density change rate within the above range, the amount of magnetic toner supplied to the blade nip can be controlled within an appropriate range. A toner having a large initial density change rate is a toner having a large density change due to tapping. A toner having a large density change due to tapping means that the toner is easily changed to a compacted state by vibration. For this reason, in the blade nip, the toner is compressed by the vibration caused by the rubbing between the developing sleeve and the developing blade. That is, by increasing the initial density change rate, the toner density change in the blade nip can be increased and the compacted state can be maintained. Although details of the mechanism of this effect are not known, the inventors presume as follows.
First, the tap density measured by tapping 30 times from the state in which the apparent density of the toner is measured as defined in the present invention is smaller than the tap density of the conventional JIS K5101. Easy to express the state. This is because, with the conventional tap density of 600 taps, the toner filling rate is gradually optimized by the tapping vibration, and the density change due to the adhesion state of the silica fine particles on the toner surface cannot be measured.
For this reason, with the conventional tap density, it is impossible to detect the adhesion or covering state of the silica fine particles on the toner surface and the fluidity of the toner imparted by the silica fine particles. The ratio of the apparent density to the tap density measured by tapping 30 times from the state where the apparent density of the toner is measured as defined in the present invention [that is, the above B / P] is the adhesion or covering state of the silica fine particles, and The change in density of the toner in the vicinity of the blade nip can be expressed in consideration of the fluidity of the toner provided by the silica fine particles. The toner in the vicinity of the blade nip in a high temperature and high humidity environment is deteriorated by embedding silica fine particles, and the fluidity is greatly reduced. For this reason, by using a toner having a large initial density change rate, even in a state where silica fine particles are embedded, the density change of the toner is large in the blade nip, so that the compacted state can be maintained.
The magnetic toner whose initial density change rate specified in the present invention falls within the range of 14.0 or more and 18.0 or less has an apparent density with respect to the tap density measured by tapping 30 times from the state where the apparent density of the toner is measured. A toner with a small ratio. By controlling the initial density change rate within this range, the toner necessary for development can be supplied to the blade nip even under conditions where the toner deteriorates in a high temperature and high humidity environment. For this reason, the effect of (2-2) can be acquired.
When the initial density change rate is less than 14.0, the ratio of the apparent density to the tap density measured by tapping 30 times from the state where the apparent density of the toner is measured is large, so that the compaction state can be maintained in the blade nip. Can not. As a result, the same toner receives the rubbing of the developing blade a plurality of times, so that charged toner is generated. As a result, in a high-temperature and high-humidity environment, toner is not supplied near the blade nip, causing ghost and white spots.
In the present invention, the initial density change rate can be adjusted to the above range by controlling the true density of the toner, the shape of the toner, the type and amount of silica fine particles, and the adhesion state thereof.
First, a method of increasing the change in the apparent density and the density at the time of tapping can be considered by setting the true density of the toner low by reducing the amount of the magnetic material of the magnetic toner. However, when the true density of the magnetic toner is less than 1.50, the initial density change rate increases, but the developability decreases and the image density tends to decrease. For this reason, the harmful effect is great as an electrophotographic developer.
Further, when the average circularity is less than 0.960 as the shape of the toner, the initial density change rate tends to be difficult to adjust within the above range even if the external addition state of the silica fine particles is controlled. When the toner has a shape with many irregularities, the frictional resistance between the toner particles is increased, so that it is considered that the density change during tapping is suppressed. Therefore, in order to achieve the above range, it is preferable that the toner has a high degree of circularity with an average circularity of 0.960 or more. In the present invention, the average circularity of the toner is more preferably 0.970 or more. Further, when the average circularity of the toner is 0.960 or more, it is preferable to coat the toner with an appropriate external additive under appropriate conditions.
As an example, a method of using silica fine particles as an external additive and adding a relatively large amount can be considered. However, in this case, although the initial density change rate is increased, there is a case where the low temperature fixability is lowered, and there is a case where member contamination is caused by an increase in free silica fine particles. Many.
Therefore, the present inventors do not externally add a large amount of silica fine particles, but by controlling the aggregation state and the coating state of the silica fine particles, the amount of silica fine particles that does not affect other performance as a developer can be reduced. It is considered preferable to control the density change rate within the above range.
For example, as one form of external addition mixing conditions for silica fine particles, the power of the drive unit 8 of the external addition device shown in FIG. 4 is externally added under weak conditions of 0.06 W / g or more and 0.15 W / g or less. Thereafter, there is a two-stage external addition in which external addition is performed under a strong condition of 0.20 W / g or more and 2.0 W / g or less. Since the external addition device shown in FIG. 4 can increase the number of collisions between toner particles in a narrow clearance portion, the force applied to the silica fine particles by the collision can be increased. Due to this effect, the external addition device shown in FIG. 4 can loosen the silica fine particles from the secondary particles to the primary particles, thereby increasing the toner coverage. Furthermore, compared with the one-stage external addition, the two-stage external addition of the above-mentioned external addition conditions diffuses the silica fine particles under a weak condition, loosens the silica fine particles under a strong condition, and efficiently puts a certain amount of silica fine particles on the toner particle surface. Can be attached. Therefore, the initial density change rate can be controlled within the above range without adding a large amount of silica fine particles.

In the present invention, [total energy amount (mJ) / toner density (g / ml)] (hereinafter also referred to as TE / density) measured by a powder fluidity measuring device equipped with a rotary propeller blade of a magnetic toner. Is 200 mJ / (g / ml) or more and 300 mJ / (g / ml) or less, preferably 220 mJ / (g / ml) or more and 280 mJ / (g / ml) or less. This [TE / density] is an index indicating the ease of releasing the toner from the compacted state, and is a numerical value of the physical resistance that the blade receives when the blade enters the compacted toner layer.
The present inventors have found that the ease of loosening of the magnetic toner at the blade nip can be controlled by controlling [TE / density] within the above-mentioned range. In the present invention, [TE / density] represents a force necessary to loosen the toner compaction state as shown in the following measurement method. At the blade nip, the developing blade loosens the compacted state of the toner. For this reason, the toner whose [TE / density] is in the above range can be easily loosened from the compacted state, and the toner can be uniformly loosened by the developing blade. That is, the effect (2-3) can be obtained.
When [TE / Density] is greater than 300 mJ / (g / ml), the force required to unravel the toner from the compacted state is large, so that the toner cannot be sufficiently unraveled by the rubbing of the developing blade. There is unevenness in the amount of loading on the sleeve. For this reason, the same toner that could not be developed is repeatedly rubbed against the developing blade, resulting in a charged toner.

By providing a toner that satisfies all of (2-1), (2-2), and (2-3) as described above, in a high-temperature and high-humidity environment that has been difficult to achieve with the prior art. In this case, toner replacement at the blade nip can be achieved for the first time.
The magnetic toner of the present invention defines the ease of embedding silica particles during durable use as follows. The embedding of silica fine particles occurs with toner deterioration. The present inventors have found that there is a correlation between “TE / density” defined in the present invention and “embedded state of silica fine particles”. As a reason for this, the present inventors speculate as follows.
In order to control [TE / density] within the scope of the present invention, it is conceivable to adopt a method according to any one of the achievement methods (A) to (C). The methods (A) to (C) may be performed independently, but may be achieved by combining a plurality of methods.
(A) Method of optimizing the particle size distribution of the magnetic toner and optimizing the amount of fine powder and coarse powder to control the packing property (B) Increasing the shape (average circularity) and surface smoothness of the magnetic toner particles, and between the toner particles (C) A method of adhering a plurality of organic and / or inorganic fine particles with optimized surface energy, degree of hydrophobicity, particle size, etc. to the surface of the magnetic toner. [TE / density] can be reduced by sharpening the particle size distribution. By sharpening the particle size distribution, it is possible to eliminate unevenness in the adhesion state of the silica fine particles between the toner particles and to eliminate the toner particle from being caught when the toner particles are released from the compacted state. As a result, the friction coefficient between the toner particles is reduced in the blade nip portion that receives the rubbing of the developing blade, and embedding of silica fine particles in the second half of the endurance use can be suppressed. In (B), [TE / density] can be reduced by increasing the average circularity of the magnetic toner particles. By increasing the average circularity, by reducing the contact area between the toner particles, it is possible to reduce the adhesion between the toner particles working in the compacted state. As a result, the friction coefficient caused by the contact of the toner particles can be reduced, and the embedding of the silica fine particles can be suppressed. In (C), [TE / density] can be reduced by appropriately attaching inorganic fine particles to the surface of the magnetic toner particles. By adhering high-fluidity inorganic fine particles to the toner, the fluidity of the toner when it is released from the compacted state can be enhanced. As a result, the friction of the toner that is received when the toner is compacted can be reduced by the high fluidity silica, so that embedding of silica fine particles can be suppressed.
As described above, even if any of the methods (A), (B), and (C) is adopted, [TE / density] can be reduced and the embedding of silica fine particles is suppressed. In the magnetic toner of the present invention, the [TE / density] is controlled in the range of 200 mJ / (g / ml) or more and 300 mJ / (g / ml) or less, so that the silica fine particles become toner particles in a high temperature and high humidity environment. It is possible to suppress the phenomenon that the toner is buried in the surface and the fluidity of the toner is lowered. That is, the effect (1) can be obtained.
2 in the above-mentioned (1) and (2), “the external additive is difficult to be embedded in the toner particles even if the durable use is advanced”, and “the replacement of the toner in the blade nip occurs even when the toner is deteriorated”. The present inventors consider that ghosts and white spots can be solved for a long time even under a high temperature and high humidity environment for the first time by two synergistic effects.

The magnetic material used in the magnetic toner of the present invention is mainly composed of triiron tetroxide or γ-iron oxide, and may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, and aluminum. Good. The shape of the magnetic material includes a polyhedron, octahedron, hexahedron, sphere, needle shape, flake shape, etc., but a polyhedron, octahedron, hexahedron, sphere and the like having a small anisotropy can reduce the image density. It is preferable in terms of enhancement. The amount of the magnetic substance contained in the magnetic toner of the present invention is preferably 50 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer or binder resin.
In addition, as magnetic characteristics when 79.6 kA / m is applied, the coercive force (Hc) is preferably 1.6 to 12.0 kA / m, and the magnetization strength (σs) is 30 to 90 Am ² / m.
Preferably, the residual magnetization (σr) is 1 to 10 Am ² / kg.

The magnetic toner of the present invention preferably contains a wax. The wax preferably includes a hydrocarbon wax. Other wax components include the following. Amide waxes, higher fatty acids, long chain alcohols, ketone waxes, ester waxes, and derivatives such as these graft compounds and block compounds. If necessary, two or more wax components may be used in combination. Among these, when the hydrocarbon wax by the Fischer-Tropsch method is used, the high temperature offset resistance can be kept good while maintaining the developability well for a long time. These hydrocarbon waxes may contain an antioxidant within a range that does not affect the chargeability of the toner.
The content of the wax is preferably 4.0 parts by mass or more and 30.0 parts by mass or less, more preferably 10.0 parts by mass or more and 25.0 parts by mass or less with respect to 100 parts by mass of the binder resin. is there.

In the toner of the present invention, a charge control agent can be contained in the magnetic toner particles as necessary. By adding a charge control agent, the charge characteristics can be stabilized, and the optimum triboelectric charge amount can be controlled according to the development system.
As the charge control agent, a known one can be used, and a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Further, when the magnetic toner particles are produced by a direct polymerization method, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous medium is particularly preferable.
The magnetic toner of the present invention can contain these charge control agents alone or in combination of two or more.
The blending amount of the charge control agent is preferably 0.3 parts by mass or more and 10.0 parts by mass or less, more preferably 0.5 parts by mass with respect to 100 parts by mass of the polymerizable monomer or binder resin. The amount is 8.0 parts by mass or more.

The magnetic toner of the present invention contains magnetic toner particles and inorganic fine particles. In the present invention, the inorganic fine particles are silica fine particles.
As an aspect of the silica fine particles used in the present invention, those produced by hydrophobizing the silica raw material with silicone oil can be preferably exemplified.
As another embodiment of the silica fine particles used in the present invention, those produced by subjecting the silica raw material to a hydrophobic treatment with a silicone oil and a silane compound and / or a silazane compound are preferably exemplified.
The degree of the hydrophobization treatment is preferably 70% or more, more preferably 80% or more, as measured by a methanol titration test, from the viewpoint of suppressing a decrease in chargeability in a high-temperature and high-humidity environment. .
Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, and fluorine modified silicone oil.
The kinematic viscosity at 25 ° C. of the silicone oil used for the silica fine particles is preferably 30 cSt or more and 500 cSt or less. When the kinematic viscosity is in the above range, it becomes easy to control the uniformity when the silica base is hydrophobized with silicone oil. Furthermore, the kinematic viscosity of the silicone oil is closely related to the molecular chain length of the silicone oil, and thus affects the number of molecular ends. It is preferable that the kinematic viscosity is in the above-mentioned range because the degree of aggregation of the silica fine particles is less deteriorated. A more preferable range of the viscosity of the silicone oil at 25 ° C. is 40 cSt or more and 300 cSt or less. Examples of the apparatus for measuring the viscosity of the silicone oil include a thin tube type kinematic viscometer (manufactured by Kashiwagi Scientific Instruments Co., Ltd.) or a fully automatic microkinematic viscometer (manufactured by Viscotech Co., Ltd.).
Examples of the silane compounds include alkoxysilanes such as methoxysilane, ethoxysilane, and propoxysilane, halosilanes such as chlorosilane, bromosilane, and iodosilane, hydrosilanes, alkylsilanes, arylsilanes, vinylsilanes, acrylic silanes, and epoxy. Examples thereof include silanes, silyl compounds, siloxanes, silylureas, silylacetamides, and silane compounds simultaneously having different substituents of these silane compounds. By using these silane compounds, fluidity, transferability and charge stabilization can be obtained. A plurality of these silane compounds may be used.
Specific examples include trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyl. Trichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldi Siloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane And dimethylpolysiloxane having 2 to 12 siloxane units per molecule, and having one hydroxyl group in Si at the terminal unit. You may use these as a 1 type, or 2 or more types of mixture.
The silazane compound is a general term for compounds having a Si—N bond in the molecule. Specifically, dimethyldisilazane, trimethyldisilazane, tetramethyldisilazane, pentamethyldisilazane, hexamethyldisilazane, octamethyltrisilazane, hexamethylcyclotrisilazane, tetraethyltetramethylcyclotetrasilazane, tetraphenyldimethyldi Examples include silazane, dipropyltetramethyldisilazane, dibutyltetramethyldisilazane, dihexyltetramethyldisilazane, dioctyltetramethyldisilazane, diphenyltetramethyldisilazane, octamethylcyclotetrasilazane, and the like. Moreover, you may use the organic fluorine-containing silazane compound etc. which substituted these silazane compounds partially with the fluorine etc. Particularly in the present invention, hexamethyldisilazane is preferably used.

As the silica raw material, both so-called wet silica produced by vapor phase oxidation of silicon halides, so-called dry method or dry silica called fumed silica, and so-called wet silica can be used. is there.
The silica fine particles used in the present invention are preferably those that have been crushed during or after the hydrophobization treatment step. Further, when the hydrophobizing treatment is performed in two stages, it is possible to perform the crushing treatment between the hydrophobizing treatment steps.
The apparent density of the silica fine particles used in the present invention is preferably 15 g / L or more and 45 g / L or less, and more preferably 18 g / L or more and 30 g / L or less. The apparent density of the silica fine particles being in the above range indicates that the silica fine particles are hardly densely packed and a large amount of air is trapped between the silica fine particles, and the apparent density is lower than that of the prior art. Therefore, even in the toner to which the silica fine particles are externally added, the toners are hardly clogged closely and the adhesion force can be reduced, so that toner deterioration in a high temperature and high humidity environment is suppressed.
Means for controlling the apparent density of the silica fine particles within the above range include the particle size of the silica raw material used for the silica fine particles, the presence / absence and the strength of the above-mentioned crushing treatment, the treatment amount of the hydrophobizing agent such as silicone oil, etc. It is mentioned to adjust. By reducing the particle size of the silica raw material, the BET specific surface area of the silica fine particles to be obtained becomes large and a large amount of air can be interposed, so that the apparent density can be reduced. Further, by performing the crushing treatment, relatively large secondary particles contained in the silica fine particles can be loosened into relatively small secondary particles, and the apparent density can be reduced. In order to produce silica fine particles having a very low apparent density as in the present invention, it is effective to perform a crushing treatment. As a means for the crushing process, a pin type crusher, a swivel type crusher, a collision type crusher, or the like is used.

The hydrophobic treatment with the silicone oil and the hydrophobic treatment with the silane compound and / or the silazane compound may be either dry treatment or wet treatment.
The specific procedure for the hydrophobic treatment with silicone oil is, for example, by reacting silica fine particles in a solvent in which silicone oil is dissolved (preferably a solvent adjusted to pH 4 with an organic acid or the like), and then removing the solvent. To do. Thereafter, a crushing process may be performed. Subsequently, when performing a hydrophobization treatment with a silane compound and / or a silazane compound, the specific procedure is to put the crushed silicone oil-treated silica fine particles into a solvent in which these are dissolved and to react. Thereafter, the solvent is removed and a crushing treatment is performed. Further, the following method may be used. For example, in the hydrophobic treatment with silicone oil, silica fine particles are placed in a reaction vessel. Then, alcohol water is added with stirring in a nitrogen atmosphere, silicone oil is introduced into the reaction vessel to perform a hydrophobization treatment, and the mixture is further heated and stirred to remove the solvent, followed by pulverization treatment. In the hydrophobization treatment with a silane compound and / or a silazane compound, the silane compound and / or the silazane compound is introduced and the hydrophobization treatment is performed with stirring in a nitrogen atmosphere. . In the silica fine particles used in the present invention, it is one of preferred embodiments that both the hydrophobization treatment of the silicone oil and the hydrophobization treatment with the silane compound and / or the silazane compound are performed. You may go first.
In the present invention, it is preferable that the silicone oil is chemically immobilized on the surface of the silica base material in the hydrophobic treatment with the silicone oil. Therefore, it is preferable to perform a heat treatment in order to chemically fix it. The heating temperature is preferably 100 ° C. or higher, and the higher the heating temperature, the more preferable. This heat treatment step is preferably performed immediately after the silicone oil treatment, but when the crushing treatment is performed, the heat treatment step may be performed after the crushing treatment step.

In order to impart good fluidity to the toner, the silica base material preferably has a specific surface area (BET specific surface area) measured by a BET method by nitrogen adsorption of 130 m ² / g or more and 330 m ² / g or less. . In the case of this range, the fluidity and chargeability imparted to the toner are easily secured through durable use. The BET specific surface area of the silica base material is more preferably 200 m ² / g or more and 320 m ² / g or less.
The specific surface area (BET specific surface area) measured by the BET method by nitrogen adsorption is measured according to JISZ8830 (2001). As a measuring device, an “automatic specific surface area / pore distribution measuring device TriStar 3000 (manufactured by Shimadzu Corporation)” which employs a gas adsorption method by a constant volume method as a measuring method is used.
Further, the number average particle size of the primary particles of the silica raw material used in the present invention is preferably 3 nm or more and 50 nm or less, and more preferably 5 nm or more and 40 nm or less.

The silica fine particles used in the present invention are preferably produced by subjecting the silica raw material to a hydrophobic treatment with silicone oil and a silane compound and / or silazane compound. Further, when the carbon amount derived from the hydrophobic treatment of the silica fine particles is C, and the carbon amount derived from the hydrophobic treatment of the silica fine particles with the silane compound and / or silazane compound is C (A), C is 4. It is preferably 0% by mass or more and 10.0% by mass or less, and the percentage [C (A) / C × 100 (%)] of C (A) to C preferably satisfies the following formula 2.
(Formula 2) 5 ≦ C (A) / C × 100 (%) ≦ 20
[C (A) / C] being in the above range means that the amount of carbon [C] derived from the total hydrophobizing agent in the silica fine particles is added so as to be able to coat the silica base, and This indicates that the amount of carbon [C (A)] derived from the silane compound and / or silazane compound is less than the amount of carbon derived from the silicone oil. In order to hydrophobize the silica base material under such conditions, it is preferable to hydrophobize the surface of the silica base material that could not be hydrophobized with silicone oil with a silane compound and / or a silazane compound. As a result, it is possible to stably obtain silica fine particles having a high degree of hydrophobicity. Thereby, the ease of toner loosening can be greatly improved. Although details of the reason why the ease of unraveling can be improved are not clear, the present inventors consider as follows. Of the silicone oil molecule ends on the surface of the silica fine particles, only one end has a degree of freedom, which affects the cohesiveness between the silica fine particles. On the other hand, by performing the hydrophobizing treatment satisfying the above formula 2, the silicone oil molecular terminals are hardly present on the outermost surface of the silica fine particles, and the cohesiveness of the silica fine particles can be greatly reduced. As a result, the cohesiveness between the toners when the silica fine particles are externally added can be greatly reduced, and the ease of toner loosening can be improved.

The magnetic toner of the present invention preferably contains silica fine particles of 0.40 parts by mass or more and 1.50 parts by mass or less per 100 parts by mass of the magnetic toner particles.
By controlling the content of the silica fine particles within the above range, the fluidity of the toner is controlled within an appropriate range, the occurrence of toner deterioration is suppressed, and a good image can be easily obtained through durable use.
When the content of the silica fine particles is less than 0.40 parts by mass, the fluidity of the toner may not be sufficient, and the deterioration of the toner tends to be promoted.

In the magnetic toner of the present invention, the coverage X1 with silica fine particles on the toner surface determined by an X-ray photoelectron spectrometer (ESCA) is 50.0 area% or more and 75.0 area% or less, and the theoretical coverage with silica fine particles. Is preferably X2, the diffusion index represented by the following formula 3 preferably satisfies the following formula 4.
(Formula 3) Diffusion index = X1 / X2
(Expression 4) Diffusion index ≧ −0.0042 × X1 + 0.62
The coverage X1 can be calculated from the ratio of the Si element detection intensity when the toner is measured to the Si element detection intensity when the silica fine particle is measured by ESCA. The coverage X1 indicates the proportion of the area of the toner particle surface that is actually covered with silica fine particles.
When the coverage X1 is 50.0 area% or more and 75.0 area% or less, it is easy to control the fluidity and chargeability of the toner to a good state through durable use. When the coverage X1 is less than 50.0 area%, it tends to be difficult to obtain the ease of toner loosening described later. For this reason, under the severe evaluation conditions as described above, the fluidity is likely to be lowered due to the deterioration of the toner, and the releasability from the developing sleeve is likely to be insufficient. It becomes a trend.
On the other hand, the theoretical coverage X2 by the silica fine particles is calculated by Formula 5 using the number of parts by mass of the silica fine particles per 100 parts by mass of the magnetic toner particles, the particle diameter of the silica fine particles, and the like. This indicates the ratio of the area that can theoretically cover the toner particle surface.
(Equation 5) Theoretical coverage X2 (area%) = 3 ^1/2 / (2π) × (dt / da) × (ρt / ρa) × C × 100
da: Number average particle diameter of silica fine particles (D1)
dt: weight average particle diameter of toner (D4)
ρa: True specific gravity of silica fine particles ρt: True specific gravity of toner C: Mass of silica fine particles / Mass of toner (C is the content of silica fine particles in the toner described later)

The physical meaning of the diffusion index represented by Equation 3 is shown below.
The diffusion index indicates the difference between the actual coverage ratio X1 and the theoretical coverage ratio X2. The degree of this divergence is considered to indicate the number of silica fine particles laminated in two and three layers in the vertical direction from the surface of the magnetic toner particles. Ideally, the diffusion index is 1, but this is a case where the coverage ratio X1 coincides with the theoretical coverage ratio X2, and there is no state where there are no two or more layers of silica particles (that is, the silica particles are This is a case where the magnetic toner surface is covered with a single layer). On the other hand, when the silica fine particles are present as secondary particles on the surface of the magnetic toner, a difference between the actually measured coverage and the theoretical coverage is generated, and the diffusion index is lowered. In other words, the diffusion index can be paraphrased as indicating the amount of silica fine particles present as secondary particles.
In the present invention, the diffusion index is preferably in the range represented by the above formula 4, and this range is considered to be larger than that of the toner manufactured by the conventional technique. A large diffusion index indicates that the amount of silica fine particles on the surface of the magnetic toner particles that are present as secondary particles is small and the amount that is present as primary particles is large. As described above, the upper limit of the diffusion index is 1.
It is preferable that the coverage X1 and the diffusion index satisfy the range represented by Equation 4 at the same time because the ease of toner loosening during pressurization can be improved. The present inventors consider this reason as follows.
Until now, it has been considered that the ease of toner loosening is improved by increasing the coverage X1 by externally adding a large amount of an external additive having a small particle size of about several nm. On the other hand, according to the study by the present inventors, it was found that when the ease of loosening of toners having different diffusion indexes was measured with the same coverage ratio X1, there was a difference in the ease of loosening of the toner. Furthermore, when the ease of loosening is measured while applying pressure, a more remarkable difference is observed. In particular, the present inventors consider that the behavior of the toner in the blade nip is more reflected on the ease of toner loosening during pressurization. For this reason, the present inventors consider that it is preferable to adjust the diffusion index to an appropriate range in addition to the coverage X1 in order to more precisely control the ease of toner loosening during pressurization.
Although the details of the reason why the ease of toner loosening is improved when the coverage X1 and the diffusion index satisfy the range represented by Equation 4 at the same time, the present inventors speculate as follows. doing. It is considered that when toner is present in a narrow and high pressure place such as a blade nip, the toner tends to be in a state of “meshing” so that external additives existing on the surface do not collide with each other. . At this time, if there are many silica fine particles present as secondary particles, the influence of meshing will increase, and it will be difficult to quickly loosen the toners.
In particular, when the toner is deteriorated, silica fine particles existing as primary particles are buried in the toner particle surface, and the fluidity of the toner is lowered. At that time, it is presumed that the influence of meshing between silica fine particles existing as secondary particles that are not buried becomes large, and hinders the ease of loosening of the toner. In the magnetic toner of the present invention, since many silica fine particles are present as primary particles, even when the toner is deteriorated, it is difficult for the toner to bite between the toner particles. Very easy to loosen into a single grain. That is, it has become possible to further improve the ease of toner loosening, which was difficult only by controlling the conventional coverage X1.
The boundary line of the diffusion index in the present invention is a function with the coverage X1 as a variable in the range where the coverage X1 is 50.0 area% or more and 75.0 area% or less. The calculation of this function is empirically obtained from the phenomenon that the toner is easily loosened when pressurized when the coverage X1 and the diffusion index are obtained by changing the silica fine particles, external addition conditions, and the like.

FIG. 2 shows the production of a magnetic toner in which the coverage X1 is arbitrarily changed by changing the amount of silica fine particles to be added using three types of external mixing conditions, and the relationship between the coverage X1 and the diffusion index is plotted. It is a graph. Of the magnetic toners plotted in this graph, it was found that the magnetic toner plotted in the region satisfying the expression 4 sufficiently improves the ease of loosening during pressurization.
Here, although details are not known about the reason why the diffusion index depends on the coverage X1, the present inventors presume as follows. In order to improve the ease of loosening of the magnetic toner at the time of pressurization, it is better that the amount of silica fine particles present as secondary particles is small, but the influence of the covering ratio X1 is not a little. As the coverage X1 increases, the ease of loosening of the magnetic toner gradually improves, so that the allowable amount of silica fine particles present as secondary particles increases. Thus, the boundary line of the diffusion index is considered to be a function with the coverage X1 as a variable. That is, there was a correlation between the coverage X1 and the diffusion index, and it was experimentally determined that it is preferable to control the diffusion index according to the coverage X1.
When the diffusion index is in the range of Equation 6 shown below, the amount of silica fine particles present as secondary particles increases, and the effect of suppressing deterioration of the magnetic toner is reduced, and the magnetic toner is easily loosened. Therefore, it tends to cause “white spots” and “ghosts” in the latter half of durable use.
(Expression 6) Diffusion index <−0.0042 × X1 + 0.62

  The toner of the present invention preferably has a weight average particle diameter (D4) of 6.0 μm or more and 10.0 μm or less, more preferably 7.0 μm or more, 9 from the viewpoint of the balance between developability and fixability. 0.0 μm or less.

  The average circularity of the magnetic toner used in the present invention is preferably 0.960 or more, and more preferably 0.970 or more. When the average circularity of the magnetic toner is 0.960 or more, the toner has a spherical shape or a shape close to it, and is excellent in fluidity and easily suppresses embedding of silica fine particles. For this reason, it becomes easy to maintain high developability even in the latter half of durable use.

  The true density of the magnetic toner of the present invention is preferably 1.40 or more and 1.70 or less, more preferably 1.50 or more and 1.65 or less. When the true density A of the magnetic toner is 1.40 or more and 1.70 or less, it is considered that the addition amount of the magnetic substance contained in the magnetic toner is appropriately adjusted. Circulation can be improved.

Hereinafter, the method for producing the magnetic toner of the present invention will be exemplified, but the present invention is not limited thereto. The method for producing the magnetic toner of the present invention is not particularly limited, and a known method can be used.
In the case of producing by a pulverization method, for example, a binder resin and a magnetic material, and other additives such as a release agent as necessary are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill. Thereafter, the toner material is dispersed or dissolved by using a heat kneader such as a heating roll, a kneader, and an extruder to disperse or dissolve the toner material. After cooling and solidification, pulverization, classification, and if necessary, surface treatment is performed to obtain magnetic toner particles. Get. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.
The pulverization can be performed by a method using a known pulverizer such as a mechanical impact type or a jet type. Further, in order to obtain a magnetic toner having a preferable circularity of the present invention, it is preferable to further heat and pulverize or to supplementarily apply a mechanical impact force. Further, a hot water bath method in which finely pulverized (classified as necessary) magnetic toner particles are dispersed in hot water, a method of passing in a hot air stream, or the like may be used.
Examples of means for applying a mechanical impact force include a method using a mechanical impact pulverizer such as a kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industry. Further, there is a method in which a mechanical impact force is applied to the magnetic toner by a force such as a compressive force or a frictional force, as in a device such as a mechano-fusion system manufactured by Hosokawa Micron Corporation or a hybridization system manufactured by Nara Machinery Co., Ltd.

The magnetic toner particles used in the present invention are preferably those produced in an aqueous medium such as a dispersion polymerization method, an association aggregation method, a dissolution suspension method, and a suspension polymerization method. More preferably, it is manufactured.
The suspension polymerization method is a method in which a polymerizable monomer and a magnetic substance, and other additives such as a polymerization initiator, a crosslinking agent, and a charge control agent are uniformly dissolved or dispersed as required to form a polymerizable monomer. A meter composition is obtained. Thereafter, the polymerizable monomer composition is dispersed in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer using a suitable stirrer, and then the polymerizable monomer in the polymerizable monomer composition is used. The toner is polymerized to obtain toner particles having a desired particle size. The toner particles obtained by this suspension polymerization method (hereinafter, also referred to as “polymerized toner particles”) have a substantially spherical shape, so that the toner particles have a predetermined average circularity and the fluidity of the toner. Is preferable because it can be increased.
In the production of the polymerized toner particles according to the present invention, known monomers can be used as the polymerizable monomer constituting the polymerizable monomer composition. Among these, styrene or a styrene derivative is preferably used alone or mixed with another polymerizable monomer from the viewpoint of the development characteristics and durability of the toner.
In the present invention, the polymerization initiator used in the suspension polymerization method preferably has a half-life of 0.5 hours or more and 30.0 hours or less during the polymerization reaction. Moreover, it is preferable that the addition amount of a polymerization initiator is 0.5 to 20.0 mass parts with respect to 100 mass parts of polymerizable monomers.
Specific examples of the polymerization initiator include azo or diazo polymerization initiators and peroxide polymerization initiators.
In the suspension polymerization method, a crosslinking agent may be added during the polymerization reaction, and a preferable addition amount is 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer. .
Here, as the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound, a carboxylic acid ester having two double bonds, a divinyl compound, and three or more. These compounds having a vinyl group are used alone or as a mixture of two or more.
Hereinafter, the production of magnetic toner particles by the suspension polymerization method will be specifically described, but the present invention is not limited thereto. The above-mentioned polymerizable monomer and magnetic material are appropriately added, and a polymerizable monomer composition uniformly dissolved or dispersed by a disperser such as a homogenizer, a ball mill, or an ultrasonic disperser is used as a dispersion stabilizer. Suspend in an aqueous medium containing At this time, the particle size of the obtained toner particles becomes sharper by using a disperser such as a high-speed stirrer or an ultrasonic disperser to obtain a desired toner particle size all at once. The polymerization initiator may be added at the same time as other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Also, a polymerization initiator dissolved in a polymerizable monomer or solvent can be added immediately after granulation and before starting the polymerization reaction.
After granulation, stirring may be performed using a normal stirrer to such an extent that the particle state is maintained and particle floating and sedimentation are prevented.
As the dispersion stabilizer, known surfactants, organic dispersants, or inorganic dispersants can be used. In particular, inorganic dispersants are less likely to produce harmful ultrafine powders, and because of their steric hindrance, dispersion stability is obtained, so even if the reaction temperature is changed, stability is not easily lost, and washing is easy and does not adversely affect the toner. Therefore, it can be preferably used. Examples of such inorganic dispersants include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, phosphate polyvalent metal salts such as hydroxyapatite, carbonates such as calcium carbonate and magnesium carbonate, calcium metasuccinate, calcium sulfate, Examples thereof include inorganic salts such as barium sulfate and inorganic compounds such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide.
These inorganic dispersants are preferably used in an amount of 0.20 parts by mass or more and 20.00 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer. Moreover, the said dispersion stabilizer may be used independently and may use multiple types together. Furthermore, you may use together 0.0001 mass part or more and 0.1000 mass part or less surfactant with respect to 100 mass parts of polymerizable monomers.
The polymerization temperature in the polymerization reaction of the polymerizable monomer is set to a temperature of 40 ° C. or higher, generally 50 ° C. or higher and 90 ° C. or lower.
After the polymerization of the polymerizable monomer is completed, the obtained polymer particles are filtered, washed, and dried by a known method to obtain magnetic toner particles. The magnetic toner of the present invention can be obtained by adding silica fine particles to the magnetic toner particles and adhering them to the surface of the magnetic toner particles. It is also possible to add a classification process to the manufacturing process (before mixing of the silica fine particles) to remove coarse powder and fine powder contained in the magnetic toner particles.
In addition to the above silica fine particles, particles having a primary particle number average particle diameter (D1) of 80 nm or more and 3 μm or less may be added to the magnetic toner of the present invention. For example, lubricants such as fluororesin powder, zinc stearate powder and polyvinylidene fluoride powder; abrasives such as cerium oxide powder, silicon carbide powder and strontium titanate powder; spacer particles such as silica affect the effect of the present invention. A small amount can be used.

As the mixing processing apparatus for externally mixing the silica fine particles, a known mixing processing apparatus can be used, but an apparatus as shown in FIG. 4 in that the initial density change rate and [TE / density] can be easily controlled. Is preferred.
FIG. 4 is a schematic diagram showing an example of a mixing treatment apparatus that can be used when externally mixing the silica fine particles used in the present invention.
The mixing processing apparatus is configured to take a share in a narrow clearance portion with respect to the magnetic toner particles and the silica fine particles, so that the surface of the magnetic toner particles is loosened from the secondary particles to the primary particles. Can adhere to.
Further, as will be described later, the coverage X1 and the diffusion index are preferable in the present invention in that the magnetic toner particles and the silica fine particles are easily circulated in the axial direction of the rotating body, and are easily sufficiently uniformly mixed before the fixing proceeds. Easy to control to range.
On the other hand, FIG. 5 is a schematic diagram showing an example of the configuration of the stirring member used in the mixing treatment apparatus.
Hereafter, the external addition mixing process of the said silica fine particle is demonstrated using FIG.4 and FIG.5.
The mixing treatment apparatus for externally mixing silica fine particles has a rotating body 2 having at least a plurality of stirring members 3 installed on the surface, a drive unit 8 that rotationally drives the rotating body, and a gap between the stirring member 3 and the stirring member 3. The main body casing 1 is provided.
The clearance (clearance) between the inner peripheral portion of the main body casing 1 and the stirring member 3 gives a uniform share to the magnetic toner particles and adheres to the surface of the magnetic toner particles while loosening the silica fine particles from the secondary particles to the primary particles. It is important to keep it constant and minute to make it easier to do.
Further, in this apparatus, the diameter of the inner peripheral portion of the main body casing 1 is not more than twice the diameter of the outer peripheral portion of the rotating body 2. FIG. 4 shows an example in which the diameter of the inner peripheral portion of the main body casing 1 is 1.7 times the diameter of the outer peripheral portion of the rotating body 2 (the diameter of the body portion excluding the stirring member 3 from the rotating body 2). If the diameter of the inner peripheral portion of the main body casing 1 is less than or equal to twice the diameter of the outer peripheral portion of the rotating body 2, the processing space in which the force acts on the magnetic toner particles is appropriately limited. A sufficient impact force is applied to the silica fine particles.
It is important to adjust the clearance according to the size of the main casing. Setting the diameter of the inner peripheral portion of the main casing 1 to about 1% or more and 5% or less is important in that a sufficient share is applied to the silica fine particles. Specifically, when the diameter of the inner peripheral part of the main body casing 1 is about 130 mm, the clearance is about 2 mm or more and about 5 mm or less. When the diameter of the inner peripheral part of the main body casing 1 is about 800 mm, the clearance is about 10 mm or more and 30 mm or less. It should be about.
In the external addition mixing step of the silica fine particles in the present invention, the rotating body 2 is rotated by the drive unit 8 using a mixing processing device, and the magnetic toner particles and the silica fine particles introduced into the mixing processing device are stirred and mixed. Then, silica fine particles are externally added and mixed on the surface of the magnetic toner particles.
As shown in FIG. 5, at least a part of the plurality of stirring members 3 serves as a stirring member 3a for feeding that sends magnetic toner particles and silica fine particles in one axial direction of the rotating body as the rotating body 2 rotates. It is formed. Further, at least a part of the plurality of stirring members 3 is formed as a return stirring member 3b that returns the magnetic toner particles and the silica fine particles to the other direction in the axial direction of the rotating body 2 as the rotating body 2 rotates. .
Here, when the raw material inlet 5 and the product outlet 6 are provided at both ends of the main casing 1 as shown in FIG. 4, the direction from the raw material inlet 5 toward the product outlet 6 (in FIG. 4). (Right direction) is called “feed direction”.
That is, as shown in FIG. 5, the plate surface of the feeding stirring member 3a is inclined so as to feed the magnetic toner particles in the feeding direction (13). On the other hand, the plate surface of the stirring member 3b is inclined so as to send the magnetic toner particles and silica fine particles in the return direction (12).
Thus, the external addition mixing process of the silica fine particles is performed on the surface of the magnetic toner particles while repeatedly performing the feed (13) in the “feed direction” and the feed (12) in the “return direction”.
The stirring members 3a and 3b are a set of a plurality of members arranged at intervals in the circumferential direction of the rotating body 2. In the example shown in FIG. 5, the stirring members 3a and 3b form a pair of two members on the rotating body 2 at an interval of 180 degrees, but three members at an interval of 120 degrees or an interval of 90 degrees. It is good also as a set of many members, such as four sheets.
In the example shown in FIG. 5, a total of 12 stirring members 3a and 3b are formed at equal intervals.
Further, in FIG. 5, D indicates the width of the stirring member, and d indicates an interval indicating the overlapping portion of the stirring member. From the viewpoint of efficiently feeding the magnetic toner particles and the silica fine particles in the feeding direction and the returning direction, it is preferable that D has a width of about 20% to 30% with respect to the length of the rotating body 2 in FIG. FIG. 5 shows an example of 23%. Furthermore, it is preferable that the stirring members 3a and 3b have some overlap d between the stirring member 3b and the stirring member when an extension line is drawn in the vertical direction from the end position of the stirring member 3a. As a result, it is possible to efficiently share the silica fine particles that are secondary particles. D is preferably 10% or more and 30% or less in terms of applying a share.
Regarding the shape of the blade, in addition to the shape shown in FIG. 5, if the magnetic toner particles can be fed in the feeding direction and the returning direction and the clearance can be maintained, the shape having a curved surface or the tip blade portion May be a paddle structure coupled to the rotating body 2 by a rod-shaped arm.

Hereinafter, the present invention will be described in more detail with reference to schematic views of the apparatus shown in FIGS.
The apparatus shown in FIG. 4 includes a rotating body 2 having at least a plurality of stirring members 3 installed on the surface thereof, a drive unit 8 that rotationally drives the rotating body 2, and a main casing provided with a gap between the stirring member 3 and the main body casing. 1 and a jacket 4 on the inner side of the main body casing 1 and the side surface 10 of the rotating body end, through which a cooling medium can flow.
Further, the apparatus shown in FIG. 4 discharges the raw material inlet 5 formed in the upper portion of the main casing 1 and the externally mixed toner from the main casing 1 to introduce magnetic toner particles and silica fine particles. For this purpose, it has a product outlet 6 formed in the lower part of the main casing 1.
Further, in the apparatus shown in FIG. 4, a raw material inlet inner piece 16 is inserted into the raw material inlet 5, and a product outlet inner piece 17 is inserted into the product outlet 6.
In the present invention, first, the raw material inlet inner piece 16 is taken out from the raw material inlet 5, and magnetic toner particles are introduced into the processing space 9 from the raw material inlet 5. Next, silica fine particles are introduced into the treatment space 9 from the raw material inlet 5, and the raw material inlet inner piece 16 is inserted. Next, the rotating body 2 is rotated by the drive unit 8 (11 indicates the direction of rotation), and the processed material introduced above is externally added while being stirred and mixed by a plurality of stirring members 3 provided on the surface of the rotating body 2. Mix.
Note that the order of loading may be such that the silica fine particles are first charged from the raw material inlet 5 and then the magnetic toner particles are charged from the raw material inlet 5. Further, after the magnetic toner particles and the silica fine particles are mixed in advance by a mixer such as a Henschel mixer, the mixture may be supplied from the raw material input port 5 of the apparatus shown in FIG.
More specifically, as the external additive mixing treatment condition, the power of the driving unit 8 is controlled to be 0.2 W / g or more and 2.0 W / g or less, so that the coverage X1 and the diffusion index defined in the present invention are determined. Is preferable in obtaining. Moreover, it is more preferable to control the power of the drive unit 8 to 0.6 W / g or more and 1.6 W / g or less.
When the power is lower than 0.2 W / g, the coverage X1 is difficult to increase and the diffusion index tends to be too low. On the other hand, when it is higher than 2.0 W / g, the diffusion index increases, but the silica fine particles tend to be embedded too much.
Although it does not specifically limit as processing time, Preferably it is 3 minutes or more and 10 minutes or less. When the treatment time is shorter than 3 minutes, the coverage X1 and the diffusion index tend to be low.
Although the rotation speed of the stirring member at the time of external mixing is not particularly limited, the shape of the stirring member 3 in the apparatus in which the volume of the processing space 9 of the apparatus shown in FIG. 4 is 2.0 × 10 ⁻³ m ³ is shown in FIG. The number of rotations of the stirring member is preferably 800 rpm or more and 3000 rpm or less. By being 800 rpm or more and 3000 rpm or less, it becomes easy to obtain the coverage X1 and the diffusion index defined in the present invention.
Further, in the present invention, a particularly preferable processing method is to have a pre-mixing step before the external addition mixing processing operation. By including the pre-mixing step, the silica fine particles are highly uniformly dispersed on the surface of the magnetic toner particles, so that the coverage X1 is likely to be increased and the diffusion index is likely to be further increased.
More specifically, as pre-mixing processing conditions, the power of the drive unit 8 is set to 0.06 W / g or more and 0.20 W / g or less, and the processing time is set to 0.5 minutes or more and 1.5 minutes or less. It is preferable. If the load power is lower than 0.06 W / g or the processing time is shorter than 0.5 minutes as the premixing processing condition, sufficient uniform mixing is difficult to perform as premixing. On the other hand, when the premixing treatment conditions are such that the load power is higher than 0.20 W / g or the treatment time is longer than 1.5 minutes, the silica fine particles are formed on the surface of the magnetic toner particles before sufficiently uniform mixing. There is a case where it is fixed.
Regarding the rotation speed of the stirring member in the pre-mixing process, when the volume of the processing space 9 of the apparatus shown in FIG. 4 is 2.0 × 10 ⁻³ m ³ and the shape of the stirring member 3 is as shown in FIG. The rotation speed of the stirring member is preferably 50 rpm or more and 500 rpm or less. By being 50 rpm or more and 500 rpm or less, it becomes easy to obtain the coverage X1 and the diffusion index defined in the present invention.
After completion of the external addition mixing process, the product discharge port inner piece 17 is taken out from the product discharge port 6, the rotating body 2 is rotated by the drive unit 8, and the magnetic toner is discharged from the product discharge port 6. From the obtained magnetic toner, coarse particles and the like are separated by a sieve such as a circular vibrating sieve as necessary to obtain a magnetic toner.

  Next, an example of an image forming apparatus that can suitably use the magnetic toner of the present invention will be described in detail with reference to FIG. In FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier (hereinafter also referred to as a photoconductor), which includes a charging member (charging roller) 117, a developing device 140 having a toner carrier 102, a transfer member (transfer charging roller). ) 114, a cleaner container 116, a fixing device 126, a pickup roller 124, and the like. The electrostatic latent image carrier 100 is charged by the charging roller 117. Then, exposure is performed by irradiating the electrostatic latent image carrier 100 with laser light from the laser generator 121, and an electrostatic latent image corresponding to the target image is formed. The electrostatic latent image on the electrostatic latent image carrier 100 is developed with a one-component toner by the developing device 140 to obtain a toner image, and the toner image is transferred in contact with the electrostatic latent image carrier via a transfer material. The image is transferred onto the transfer material by the roller 114. The transfer material on which the toner image is placed is conveyed to the fixing device 126 and fixed on the transfer material. Further, the toner partially left on the electrostatic latent image carrier is scraped off by the cleaning blade and stored in the cleaner container 116.

Next, it describes regarding the measuring method of each physical property which concerns on this invention.
<Measurement Method of Apparent Density and Tap Density of Magnetic Toner and Calculation Method of Initial Density Change>
The apparent density and tap density of the magnetic toner are measured by the following method using a powder property evaluation apparatus (powder tester, manufactured by Hosokawa Micron).
Magnetic toner was uniformly supplied from above through a sieve having a mesh size of 608 μm (24 mesh) into a cylindrical container having a diameter of 5.03 cm and a volume of 100 cm ³ for 30 seconds. The supply speed at this time was adjusted so that the magnetic toner was sufficiently filled in the cylindrical container in 30 seconds. Leveling immediately after supplying 30 seconds magnetic toner of the upper surface of the cylindrical container by a blade, and measuring the magnetic toner mass of the cylindrical container, to obtain the apparent density (g / cm ³⁾ of the magnetic toner mass ÷ 100. This operation was performed 5 times, and the average value was defined as the apparent density (g / cm ³ ) in the present invention.
After measuring the apparent density, a cylindrical cap is fitted into the cylindrical container, and magnetic toner is added to the upper edge of the container, and tapping with a tap height of 1.8 cm is performed 30 times. After completion, the cap is removed, and the magnetic toner on the upper surface of the cylindrical container is scraped off with a blade, and the magnetic toner mass in the cylindrical container is measured. A tap density (g / cm ³ ) is obtained. This operation was performed 5 times, and the average value was defined as the tap density in the present invention.
On the other hand, the initial density change rate was determined from the initial density change rate = (1−B / P) × 100.

<Measurement method of total energy (TE) amount; total energy)>
TE in the present invention is measured using a powder fluidity analyzer (powder rheometer FT-4, manufactured by Freeman Technology) (hereinafter abbreviated as FT-4) equipped with a rotary propeller blade.
Specifically, the measurement is performed by the following operation. In all operations, the propeller blade is a 23.5 mm diameter blade dedicated to FT-4 measurement (see FIG. 6A). The rotation axis is in the normal direction around the center of the 23.5 mm × 6.5 mm blade plate. The blade plate is smoothly twisted counterclockwise such that both outermost edge portions (12 mm from the rotating shaft) are 70 ° and a portion 6 mm from the rotating shaft is 35 ° (FIG. 6). (See (b)), and the material is SUS.
First, a dedicated container for FT-4 measurement [a split container (model number: C4031) having a diameter of 25 mm and a volume of 25 ml, a height of about 51 mm from the bottom of the container to the split part. Hereinafter, it is also simply referred to as a container. The toner powder layer is formed by compressing 24 g of toner left in a 60 ° C. environment at 23 ° C. for 3 days.
For compression of the toner, a compression test piston (diameter 24 mm, height 20 mm, lower mesh tension) is used instead of the propeller blade.
(1) Consolidation operation of toner 8 g of toner is added to the above-mentioned container exclusively for FT-4 measurement. A compression piston dedicated to FT-4 measurement is attached and consolidation is performed at 40N for 60 seconds. Further, 8 g of toner is added, and the compression operation is performed three times in a similar manner so that a total of 24 g of the compacted toner is in a dedicated container.
(2) Split operation A toner powder layer having the same volume (25 ml) is formed by scraping off the toner powder layer at the split portion of the above-described FT-4 measurement container and removing the toner on the toner powder layer.
(3) Measurement operation (A) The peripheral speed of the blade (the peripheral speed of the outermost edge of the blade) in the clockwise direction (the direction in which the toner powder layer is not pushed in by the rotation of the blade) with respect to the surface of the toner powder layer ) Is 10 mm / sec, and the angle between the trajectory drawn by the outermost edge of the moving blade and the surface of the powder layer (hereinafter referred to as “blade trajectory angle”) is the vertical entry speed to the toner powder layer. The propeller blade is advanced to a position 10 mm from the bottom of the toner powder layer at a speed of 5 (deg).
(B) Thereafter, in the clockwise rotation direction with respect to the surface of the toner powder layer, the peripheral speed of the blade is set to 60 mm / sec. deg), and the propeller blade is advanced from the bottom of the toner powder layer to a position of 1 mm.
(C) Thereafter, in the counterclockwise rotation direction with respect to the surface of the toner powder layer, the peripheral speed of the blade is 10 mm / sec, the extraction speed in the vertical direction from the toner powder layer is 5 The speed is set to (deg), and the blade is moved to a position of 80 mm from the bottom surface of the toner powder layer to perform extraction. When the extraction is completed, the toner attached to the blade is wiped off by rotating the blade alternately in small clockwise and counterclockwise directions.
In the measurement operation (A), the propeller blade is rotated to enter the toner powder layer in the container, and the measurement is started from a position 60 mm from the bottom surface of the toner powder layer. TE is defined as the sum of rotational torque and vertical load obtained when the propeller-type blade is advanced. By dividing the obtained TE by the toner density in the cell at the time of measurement (the toner density is automatically measured by FT-4), [TE / density] in the present invention is obtained. The reason for dividing by the density is to eliminate factors such as filling efficiency during measurement.

<Quantification method of silica fine particles>
(1) Quantification of content of silica fine particles in magnetic toner (standard addition method)
3 g of magnetic toner is placed in an aluminum ring having a diameter of 30 mm, and pellets are produced at a pressure of 10 tons. Then, the intensity of silicon (Si) is obtained by wavelength dispersive X-ray fluorescence analysis (XRF) (Si intensity-1). The measurement conditions may be those optimized by the XRF apparatus to be used, but all the series of intensity measurements are performed under the same conditions. Silica fine particles having a primary particle number average particle size of 12 nm are added to the magnetic toner in an amount of 1.0 mass% with respect to the magnetic toner, and mixed by a coffee mill.
After mixing, after pelletizing in the same manner as described above, the strength of Si is obtained in the same manner as described above (Si strength -2). The same operation is performed to obtain Si strength (Si strength-3, Si strength-4) in a sample in which silica fine particles are added and mixed at 2.0 mass% and 3.0 mass% with respect to the toner. The silica content (mass%) in the toner is calculated by the standard addition method using Si strengths −1 to 4.
(2) Separation of silica fine particles from magnetic toner 5 g of magnetic toner is weighed in a 200 ml polycup with a lid using a precision balance, added with 100 ml of methanol, and dispersed for 5 minutes with an ultrasonic disperser. Attract magnetic toner with a neodymium magnet and discard the supernatant. After repeating the operation with methanol and discarding the supernatant three times, 100 ml of 10% NaOH and “Contaminone N” (non-ionic surfactant, anionic surfactant, organic builder pH7 precision measuring instrument washing A few drops of a 10% by weight aqueous neutral detergent solution (manufactured by Wako Pure Chemical Industries, Ltd.) are added and mixed gently, and then allowed to stand for 24 hours. Then, it isolate | separates again using a neodymium magnet. At this time, rinse with distilled water repeatedly so that NaOH does not remain. The collected particles are sufficiently dried by a vacuum dryer to obtain particles A. By the above operation, the externally added silica fine particles are dissolved and removed.
(3) Measurement of Si intensity in particle A 3 g of particle A is put in an aluminum ring having a diameter of 30 mm, a pellet is prepared at a pressure of 10 tons, and the intensity of Si is obtained by wavelength dispersive X-ray fluorescence analysis (XRF). (Si strength -5). The silica content (mass%) in the particles A is calculated using Si strength -5 and Si strength -1 to 4 used in the determination of the silica content in the magnetic toner.
(4) Separation of magnetic material from toner To 5 g of particles A, 100 ml of tetrahydrofuran is added and mixed well, followed by ultrasonic dispersion for 10 minutes. Attract magnetic particles with a magnet and discard the supernatant. This operation is repeated 5 times to obtain particles B. By this operation, organic components such as resin other than the magnetic substance can be almost removed. However, since there is a possibility that the insoluble content of tetrahydrofuran in the resin may remain, it is preferable to burn the remaining organic component by heating the particle B obtained by the above operation to 800 ° C., and the particle obtained after the heating. C can be approximated to the magnetic material contained in the toner.
By measuring the mass of the particles C, the magnetic substance content W (% by mass) in the magnetic toner can be obtained. At this time, in order to correct the increase in the oxidation amount of the magnetic material, the mass of the particle C is multiplied by 0.9666 (Fe ₂ O ₃ → Fe ₃ O ₄ ). By substituting each quantitative value into the following equation, the amount of silica particles added externally is calculated.
Externally added silica fine particle content (mass%) = silica content in magnetic toner (mass%) − silica content in particles A (mass%)

<Measurement method of coverage X1>
The coverage X1 with the silica fine particles on the toner surface is calculated as follows.
The following apparatus is used under the following conditions, and elemental analysis of the toner surface is performed.
-Measuring device: Quantum 2000 (trade name, manufactured by ULVAC-PHI Co., Ltd.)
・ X-ray source: Monochrome Al Kα
-Xray Setting: 100 μmφ (25 W (15 KV))
・ Photoelectron extraction angle: 45 degrees ・ Neutralization condition: Combined use of neutralizing gun and ion gun ・ Analysis area: 300 × 200 μm
・ Pass Energy: 58.70eV
・ Step size: 1.25eV
・ Analysis software: Maltipak (PHI)
Here, for the calculation of the quantitative value of Si atoms, peaks of C 1c (BE 280 to 295 eV), O 1s (BE 525 to 540 eV) and Si 2p (BE 95 to 113 eV) were used. used. The quantitative value of the Si element obtained here is Y1. Next, in the same manner as the elemental analysis of the toner surface described above, the elemental analysis of the silica fine particles is performed, and the obtained quantitative value of the Si element is Y2.
In the present invention, the coverage X1 with silica fine particles on the toner surface is defined by the following equation using Y1 and Y2.
Coverage ratio X1 (area%) = Y1 / Y2 × 100
In order to improve the accuracy of this measurement, it is preferable to measure Y1 and Y2 twice or more.
When obtaining the quantitative value Y2, if the silica fine particles used for the external addition can be obtained, measurement may be performed using the silica fine particles.
When silica fine particles separated from the toner surface are used as a measurement sample, the silica fine particles are separated from the toner particles according to the following procedure.
1) In the case of magnetic toner First, in 10 mL of ion exchange water, 10% by weight aqueous solution of neutral detergent for cleaning a precision measuring instrument having a pH of 7, comprising non-ionic surfactant, anionic surfactant, and organic builder. 6 ml of Wako Pure Chemical Industries, Ltd.) is added to prepare a dispersion medium. To this dispersion medium, 5 g of toner is added and dispersed with an ultrasonic disperser for 5 minutes. After that, it is set on “KM Shaker” (model: V.SX) manufactured by Iwaki Sangyo Co., Ltd. and shaken for 20 minutes under the condition of 350 reciprocations per minute. Thereafter, the toner particles are restrained using a neodymium magnet, and the supernatant is collected. Silica fine particles are collected by drying the supernatant. If a sufficient amount of silica fine particles cannot be collected, this operation is repeated.
In this method, when an external additive other than the silica fine particles is added, the external additive other than the silica fine particles is also collected. In such a case, the silica fine particles may be selected from the collected external additive using a centrifugal separation method or the like.
2) In the case of non-magnetic toner: 160 g of sucrose (manufactured by Kishida Chemical) is added to 100 ml of ion-exchanged water, and dissolved with a hot water bath to prepare a sucrose concentrate. A sucrose concentrate 31 g and 6 mL of Contaminone N are put into a centrifuge tube to prepare a dispersion. 1 g of toner is added to this dispersion and the mass of toner is loosened with a spatula or the like.
The centrifuge tube is shaken with the above shaker for 20 minutes under the condition of 350 reciprocations per minute. After shaking, the solution is replaced with a glass tube for swing rotor (50 mL), and centrifuged with a centrifuge at 3500 rpm for 30 min. In the glass tube after centrifugation, toner is present in the uppermost layer and silica fine particles are present in the lower aqueous solution side. The lower layer aqueous solution is collected, centrifuged, sucrose and silica fine particles are separated, and silica fine particles are collected. If necessary, centrifugation is repeated, and after sufficient separation, the dispersion is dried and silica fine particles are collected.
As in the case of the magnetic toner, when an external additive other than the silica fine particles is added, the external additive other than the silica fine particles is also collected. Therefore, silica fine particles are selected from the collected external additives using a centrifugal separation method or the like.

<Weight average particle diameter (D4) and particle size distribution of magnetic toner>
The weight average particle diameter (D4) of the magnetic toner is calculated as follows (also calculated in the case of magnetic toner particles). As a measuring device, a precise particle size distribution measuring device “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter, Inc.) using a pore electrical resistance method equipped with an aperture tube of 100 μm is used. For setting the measurement conditions and analyzing the measurement data, the attached dedicated software “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter, Inc.) is used. The measurement is performed with 25,000 effective measurement channels.
As the electrolytic aqueous solution used for the measurement, special grade sodium chloride is dissolved in ion-exchanged water so as to have a concentration of about 1% by mass, for example, “ISOTON II” (manufactured by Beckman Coulter, Inc.) can be used.
Prior to measurement and analysis, the dedicated software is set as follows.
On the “Change Standard Measurement Method (SOM)” screen of the dedicated software, set the total count in the control mode to 50000 particles, set the number of measurements once, and set the Kd value to “standard particles 10.0 μm” (Beckman Coulter, Inc.) Set the value obtained using By pressing the “Threshold / Noise Level Measurement Button”, the threshold and noise level are automatically set. In addition, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the “aperture tube flush after measurement” is checked.
In the “Pulse to particle size conversion setting” screen of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bin, and the particle size range is set to 2 μm to 60 μm.
The specific measurement method is as follows.
(1) About 200 ml of the electrolytic solution is placed in a glass 250 ml round bottom beaker exclusively for Multisizer 3, set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rpm. Then, dirt and bubbles in the aperture tube are removed by the “aperture flush” function of the dedicated software.
(2) About 30 ml of the electrolytic aqueous solution is put into a glass 100 ml flat bottom beaker. In this, "Contaminone N" (nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for pH7 precision measuring instrument cleaning, made by organic builder, manufactured by Wako Pure Chemical Industries, Ltd. About 0.3 ml of a diluted solution obtained by diluting 3) with ion-exchanged water is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are incorporated with the phase shifted by 180 degrees, and an ultrasonic disperser “Ultrasonic Dispersion System Tetora 150” (manufactured by Nikka Ki Bios) having an electrical output of 120 W is prepared. About 3.3 l of ion-exchanged water is placed in the water tank of the ultrasonic disperser, and about 2 ml of Contaminone N is added to the water tank.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. And the height position of a beaker is adjusted so that the resonance state of the liquid level of the electrolyte solution in a beaker may become the maximum.
(5) In a state where the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves, about 10 mg of magnetic toner is added to the electrolytic aqueous solution little by little and dispersed. Then, the ultrasonic dispersion process is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water tank is appropriately adjusted so as to be 10 ° C. or higher and 40 ° C. or lower.
(6) To the round bottom beaker (1) installed in a sample stand, the electrolytic aqueous solution (5) in which magnetic toner is dispersed is dropped using a pipette, and the measurement concentration is adjusted to about 5%. To do. Measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed with the dedicated software attached to the apparatus, and the weight average particle diameter (D4) is calculated. The “average diameter” on the “analysis / volume statistics (arithmetic average)” screen when the graph / volume% is set in the dedicated software is the weight average particle diameter (D4).

<Method for measuring number average particle diameter of primary particles of silica fine particles>
The number average particle size of the primary particles of the silica fine particles is calculated from the silica fine particle image on the surface of the magnetic toner photographed by Hitachi Ultra High Resolution Field Emission Scanning Electron Microscope S-4800 (Hitachi High-Technologies Corporation). The image capturing conditions of S-4800 are as follows.
(1) Sample preparation A thin conductive paste is applied to a sample table (aluminum sample table 15 mm × 6 mm), and magnetic toner is sprayed thereon. Further, air is blown to remove excess magnetic toner from the sample stage and sufficiently dry. The sample stage is set on the sample holder, and the height of the sample stage is adjusted to 36 mm by the sample height gauge.
(2) S-4800 observation condition setting The number average particle diameter of the primary particles of the silica fine particles is calculated using an image obtained by the reflected electron image observation of S-4800. Since the reflected electron image has less charge-up of the silica fine particles than the secondary electron image, the particle size of the silica fine particles can be accurately measured.
Liquid nitrogen is poured into the anti-contamination trap attached to the S-4800 mirror until it overflows, and is placed for 30 minutes. The “PC-SEM” of S-4800 is activated and flushing (cleaning of the FE chip as an electron source) is performed. Click the acceleration voltage display part of the control panel on the screen and press the [Flushing] button to open the flushing execution dialog. Confirm that the flushing intensity is 2 and execute. Confirm that the emission current by flashing is 20-40 μA. Insert the sample holder into the sample chamber of the S-4800 mirror. Press [Origin] on the control panel to move the sample holder to the observation position.
Click the acceleration voltage display section to open the HV setting dialog, and set the acceleration voltage to [0.8 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select [Up (U)] and [+ BSE] for the SE detector, and select [+ BSE] in the selection box on the right. L. A. 100] to select a mode in which observation is performed with a reflected electron image. Similarly, in the [Basic] tab of the operation panel, the probe current of the electron optical system condition block is set to [Normal], the focus mode is set to [UHR], and the WD is set to [3.0 mm]. Press the [ON] button in the acceleration voltage display section of the control panel to apply the acceleration voltage.
(3) Calculation of number average particle diameter (D1) of silica fine particles (above da) Drag in the magnification display section of the control panel to set the magnification to 100000 (100k). The focus knob [COARSE] on the operation panel is rotated, and the aperture alignment is adjusted when the focus is achieved to some extent. Click [Align] on the control panel to display the alignment dialog and select [Beam]. The STIGMA / ALIGNMENT knob (X, Y) on the operation panel is rotated to move the displayed beam to the center of the concentric circle. Next, [Aperture] is selected, and the STIGMA / ALIGNMENT knobs (X, Y) are turned one by one to stop the movement of the image or adjust the movement to the minimum. Close the aperture dialog and focus with auto focus. Repeat this operation two more times to focus.
Thereafter, the particle diameter of at least 300 silica fine particles on the surface of the magnetic toner is measured to obtain an average particle diameter. Here, since some silica fine particles exist as agglomerates, the number average particle size of primary particles of silica fine particles (by calculating the maximum diameter of those that can be confirmed as primary particles and arithmetically averaging the obtained maximum diameter ( D1) Obtain (da).

<Method for Measuring Average Circularity of Magnetic Toner Particles>
The average circularity of the magnetic toner particles is measured by a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation) under the measurement and analysis conditions at the time of calibration work (also measured in the case of magnetic toner).
A specific measurement method is as follows. First, about 20 ml of ion-exchanged water from which impure solids are removed in advance is put in a glass container. In this, "Contaminone N" (nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for pH7 precision measuring instrument cleaning, made by organic builder, manufactured by Wako Pure Chemical Industries, Ltd. About 0.2 ml of a diluted solution obtained by diluting the solution with ion exchange water about 3 times by mass. Further, about 0.02 g of a measurement sample is added, and dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of a dispersion liquid may become 10 to 40 degreeC. As the ultrasonic disperser, a desktop type ultrasonic cleaner disperser (for example, “VS-150” (manufactured by VervoCrea)) having an oscillation frequency of 50 kHz and an electric output of 150 W is used. Ion exchange water is added, and about 2 ml of the above-mentioned Contaminone N is added to this water tank.
For the measurement, the flow type particle image analyzer equipped with “UPlanApro” (magnification: 10 ×, numerical aperture: 0.40) as an objective lens is used. It was used. The dispersion prepared according to the above procedure is introduced into the flow type particle image analyzer, and 3000 magnetic toner particles are measured in the total count mode in the HPF measurement mode. Then, the binarization threshold at the time of particle analysis is set to 85%, the analysis particle diameter is limited to the equivalent circle diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the magnetic toner particles is obtained.
In the measurement, automatic focus adjustment is performed using standard latex particles (eg, “RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A” manufactured by Duke Scientific) diluted with ion-exchanged water before starting the measurement. Thereafter, it is preferable to perform focus adjustment every two hours from the start of measurement.
In the present invention, a flow type particle image measuring apparatus that has been calibrated by Sysmex Corporation and that has been issued a calibration certificate issued by Sysmex Corporation is used. Measurement is performed under the measurement and analysis conditions when the calibration certificate is received, except that the analysis particle diameter is limited to a circle equivalent diameter of 1.985 μm or more and less than 39.69 μm.
The measurement principle of the flow-type particle image measuring device “FPIA-3000” (manufactured by Sysmex Corporation) is to take a flowing particle as a still image and perform image analysis. The sample added to the sample chamber is fed into the flat sheath flow cell by a sample suction syringe. The sample fed into the flat sheath flow is sandwiched between sheath liquids to form a flat flow. The sample passing through the flat sheath flow cell is irradiated with strobe light at 1/60 second intervals, and the flowing particles can be photographed as a still image. Further, since the flow is flat, the image is taken in a focused state. The particle image is picked up by a CCD camera, and the picked-up image is image-processed at an image processing resolution of 512 × 512 pixels (0.37 × 0.37 μm per pixel), the contour of each particle image is extracted, and the particle image The projected area S, the perimeter L, etc.
Next, the equivalent circle diameter and the circularity are obtained using the area S and the peripheral length L. The equivalent circle diameter is the diameter of a circle having the same area as the projected area of the particle image, and the circularity is a value obtained by dividing the circumference of the circle obtained from the equivalent circle diameter by the circumference of the projected particle image. Defined and calculated by the following formula.
Circularity = 2 × (π × S) ^1/2 / L
When the particle image is circular, the circularity is 1.000. The greater the degree of irregularities on the outer periphery of the particle image, the smaller the circularity. After calculating the circularity of each particle, the range of the circularity of 0.200 to 1.000 is divided into 800, the arithmetic average value of the obtained circularity is calculated, and the value is defined as the average circularity.

<Measurement of apparent density of silica fine particles>
The apparent density of silica fine particles is measured by slowly adding a measurement sample placed on a paper to a 100 ml graduated cylinder to 100 ml, and obtaining the mass difference between the graduated cylinder before and after adding the sample by calculate. When adding the sample to the graduated cylinder, be careful not to strike the paper.
Apparent density (g / L) = (mass (g) when 100 ml was charged) /0.1

<Measurement method of carbon amount derived from hydrophobization treatment of silica fine particles>
Carbon amount [C (mass%)] derived from hydrophobic treatment of silica fine particles, and carbon amount [C (A) (mass%)] derived from hydrophobic treatment of silica fine particles with a silane compound and / or silazane compound Is measured by the following procedure.
(Extraction of silicone oil)
(1) Place 0.50 g of silica fine particles and 40 ml of chloroform in a beaker and stir for 2 hours.
(2) Stop stirring and let stand for 12 hours.
(3) The sample is filtered and washed three times with 40 ml of chloroform.
(Measurement of carbon content)
The sample is burned at 1100 ° C. in an oxygen stream, and the amount of generated CO and CO ₂ is measured by IR absorbance to measure the amount of carbon in the sample. By comparing the amount of carbon before and after extraction of chloroform, the amount of carbon derived from the hydrophobization treatment with the silane compound and / or silazane compound [C (A) (mass%)], derived from the hydrophobization treatment of the silica fine particles The amount of carbon [C (mass%)] is calculated.
(1) 2 g of sample is put into a cylindrical mold and pressed.
(2) 0.15 g of the pressed sample is precisely weighed, placed on a combustion board, and measured with Horiba EMA-110.
(3) Let the carbon amount measured after chloroform extraction be [C (A) (mass%)] derived from the hydrophobization process by a silane compound and / or a silazane compound. The amount of carbon measured before chloroform extraction is defined as the amount of carbon [C (mass%)] derived from the hydrophobization treatment of silica fine particles.

<Measurement method of true density of toner and silica fine particles>
The true density of the toner and silica fine particles was measured by a dry automatic densimeter autopycnometer (manufactured by Yuasa Ionics). The conditions are as follows.
Cell: SM cell (10 ml)
Sample amount: about 2.0 g (toner), 0.05 g (silica fine particles)
This measurement method measures the true density of a solid / liquid based on a gas phase substitution method. Similar to the liquid phase replacement method, it is based on Archimedes' principle, but uses a gas (argon gas) as a replacement medium, and therefore has high accuracy for micropores.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, all the parts and% of an Example and a comparative example are mass references | standards unless there is particular notice.

<Production example of magnetic body 1>
During an aqueous ferrous sulfate solution, 1.10 eq of sodium hydroxide solution from 1.00 relative to iron element, the amount of _P 2 _{O 5} to an iron element to be 0.15% by mass in terms of phosphorus, the iron element On the other hand, SiO ₂ in an amount of 0.50% by mass in terms of silicon element was mixed to prepare an aqueous solution containing ferrous hydroxide. The pH of the aqueous solution was 8.0, and an oxidation reaction was performed at 85 ° C. while blowing air to prepare a slurry liquid having seed crystals.
Subsequently, after adding ferrous sulfate aqueous solution so that it may become 0.90 to 1.20 equivalent with respect to the original alkali amount (sodium component of caustic soda) to this slurry liquid, the slurry liquid is maintained at pH 7.6, The oxidation reaction was promoted while blowing air to obtain a slurry liquid containing magnetic iron oxide. After filtration and washing, the water-containing slurry was once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample was put into another aqueous medium without drying, stirred and redispersed with a pin mill while circulating the slurry, and the pH of the redispersed liquid was adjusted to about 4.8. Then, 1.6 parts by mass of n-hexyltrimethoxysilane coupling agent with respect to 100 parts by mass of magnetic iron oxide (the amount of magnetic iron oxide was calculated as a value obtained by subtracting the water content from the water-containing sample) was added with stirring. Hydrolysis was performed. Thereafter, the mixture was sufficiently stirred, and the dispersion was subjected to surface treatment at a pH of 8.6. The produced hydrophobic magnetic material is filtered with a filter press, washed with a large amount of water, dried at 100 ° C. for 15 minutes, and then at 90 ° C. for 30 minutes. 0.21 μm magnetic body 1 was obtained.

<Example of production of polyester resin 1>
The following components were placed in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, and reacted for 10 hours while distilling off the water produced at 230 ° C. under a nitrogen stream.
-Bisphenol A propylene oxide 2 mol adduct 75 parts by mass-Bisphenol A propylene oxide 3 mol adduct 25 parts by mass-100 parts by mass terephthalic acid-0.25 parts by mass titanium catalyst (titanium dihydroxybis (triethanolamate))
Next, the reaction was carried out under reduced pressure of 5 to 20 mmHg, and when the acid value became 2 mgKOH / g or less, it was cooled to 180 ° C., 10 parts by weight of trimellitic anhydride was added, taken out after reaction for 2 hours under normal pressure sealing, After cooling to 0, pulverization gave polyester resin 1. The obtained polyester resin 1 had a main peak molecular weight (Mp) of 10,500 as measured by gel permeation chromatography (GPC).

In the present invention, silica fine particles having physical properties shown in Table 2 were prepared under the following production conditions.
<Production Example of Silica Fine Particle 1>
A solution obtained by diluting 20 parts by mass of dimethyl silicone oil (kinematic viscosity at 25 ° C .: 50 cSt) with 10,000 parts by mass of hexane, fumed silica (silica base; spherical, number average particle size of primary particles: 8 nm) 100 parts by mass Part was gradually added and reacted at 130 ° C., and then the solvent was removed (Table 1: Oil treatment). Then, what was pulverized using a pin type pulverizer is put into a solution in which 10 parts by mass of 90% methanol water and 10 parts by mass of hexamethylene disilazane are dissolved in 10,000 parts by mass of hexane. By reacting (Table 1: Silazane treatment), the solvent and by-products were removed to obtain silica fine particles 1. The number average particle diameter of the primary particles of the obtained silica fine particle 1 was 6 nm. The physical properties of the silica fine particles 1 are shown in Table 2.

<Production example of silica fine particles 2 to 10>
In the production example of the silica fine particles 1, the same procedure was carried out except that the particle size of the silica raw material, the number of added silicone oil, the strength of the crushing treatment, the order of the silazane treatment and the oil treatment of the hydrophobization treatment were changed. Silica fine particles 2 to 10 were produced as shown in FIG. In addition, the silazane treatment was not performed in the production of the silica fine particles 7. The physical properties of the obtained silica fine particles 2 to 10 are shown in Table 2.

<Production Example of Magnetic Toner Particle 1>
After 450 parts by mass of 0.1 M Na ₃ PO ₄ aqueous solution was added to 720 parts by mass of ion-exchanged water and heated to 60 ° C., 67.7 parts by mass of 1.0 M CaCl ₂ aqueous solution was added to stabilize the dispersion. An aqueous medium containing the agent was obtained.
-Styrene 78.0 parts by mass-n-butyl acrylate 22.0 parts by mass-Divinylbenzene 0.6 parts by mass-Iron complex of monoazo dye (T-77: Hodogaya Chemical Co., Ltd.) 3.0 parts by mass Magnetic body 1 90.0 parts by mass / Polyester resin 1 5.0 parts by mass The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.) to obtain a polymerizable monomer composition. . The obtained polymerizable monomer composition was heated to 60 ° C., and 15.0 parts by mass of Fischer-Tropsch wax (HNP-51, manufactured by Nippon Seiwa Co., Ltd., melting point: 74 ° C., number average molecular weight Mn: 500) was added. After adding, mixing and dissolving, 7.0 parts by mass of dilauroyl peroxide as a polymerization initiator was dissolved to obtain a toner composition.
The toner composition was put into the aqueous medium, and granulated by stirring at 12,000 rpm for 10 minutes with a TK homomixer (Special Machine Industries Co., Ltd.) in an N ₂ atmosphere at 60 ° C. Thereafter, the mixture was reacted at 74 ° C. for 6 hours while stirring with a paddle stirring blade.
After completion of the reaction, the suspension was cooled, washed with hydrochloric acid, filtered and dried to obtain magnetic toner particles 1. Table 3 shows the physical properties of the magnetic toner particles 1 thus obtained.

<Production example of magnetic toner particles 2 to 5>
In the production example of magnetic toner particles 1, the rotational speed of the homomixer is reduced to 11000 rpm (magnetic toner particles 2), 10500 rpm (magnetic toner particles 3), 9000 rpm (magnetic toner particles 4), and 7500 rpm (magnetic toner particles 5). Magnetic toner particles 2 to 5 were produced in the same manner except that. Table 3 shows the physical properties of the magnetic toner particles 2 to 5 obtained.

<Production Example of Magnetic Toner Particle 6>
Magnetic toner particles 6 were obtained in the same manner as in the production example of magnetic toner particles 1 except that the amount of magnetic substance 1 added was changed to 55.0 parts by mass instead of 90.0 parts by mass. Table 3 shows the physical properties of the magnetic toner particles 6 thus obtained.

<Example of production of magnetic toner particles 7>
Magnetic toner particles 7 were obtained in the same manner as in the production example of magnetic toner particles 1 except that the amount of magnetic substance 1 added was changed to 110.0 parts by mass instead of 90.0 parts by mass. Table 3 shows the physical properties of the magnetic toner particles 7 obtained.

<Production Example of Magnetic Toner Particle 8>
Magnetic toner particles 8 were obtained in the same manner as in the production example of magnetic toner particles 1 except that the amount of magnetic substance 1 added was changed to 50.0 parts by mass instead of 90.0 parts by mass. Table 3 shows the physical properties of the magnetic toner particles 8 obtained.

<Example of production of magnetic toner particles 9>
Magnetic toner particles 9 were obtained in the same manner as in the production example of magnetic toner particles 1 except that the amount of magnetic substance 1 added was changed to 115.0 parts by mass instead of 90.0 parts by mass. Table 3 shows the physical properties of the magnetic toner particles 9 obtained.

<Production Example of Magnetic Toner Particle 10>
Styrene acrylic copolymer 100 parts by mass (mass ratio of styrene and n-butyl acrylate is 78.0: 22.0, main peak molecular weight Mp is 10,000)
• 90 parts by mass of magnetic substance 1 • Iron complex of monoazo dye (T-77: Hodogaya Chemical Co., Ltd.) 2 parts by mass • Fischer-Tropsch wax (HNP-51) 4 parts by mass (manufactured by Nippon Seiwa Co., Ltd., melting point: 74 ° C., number average molecular weight Mn: 500)
The above mixture was premixed with a Henschel mixer, then melt kneaded with a biaxial extruder heated to 110 ° C., and the cooled kneaded product was coarsely pulverized with a hammer mill to obtain a coarsely pulverized toner product. The obtained coarsely pulverized product was coated with a mechanical pulverizer turbo mill (manufactured by Turbo Kogyo Co., Ltd .; coated with chromium alloy plating containing chromium carbide on the rotor and stator surfaces (plating thickness 150 μm, surface hardness HV1050)). And then pulverized by mechanical pulverization. The finely pulverized product obtained was classified and removed simultaneously with a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect.
The obtained raw material toner particles were subjected to surface modification and fine powder removal using a surface modification device faculty (manufactured by Hosokawa Micron Corporation) to obtain magnetic toner particles 10. The surface modification and fine powder removal conditions using the surface modification equipment faculty were as follows. The rotational peripheral speed of the dispersion rotor was 150 m / sec, and the amount of finely pulverized product was 7.6 kg per cycle. The time (cycle time: the time from the end of the raw material supply to the opening of the discharge valve) was 82 seconds. The temperature when discharging the toner particles was 44 ° C. Table 3 shows the physical properties of the magnetic toner particles 10 thus obtained.

<Production Example of Magnetic Toner Particle 11>
100 parts by mass of magnetic toner particles 10 and 0.50 parts by mass of silica fine particles 6 were mixed with a Henschel mixer FM10C (Mitsui Miike Chemical Co., Ltd.) and externally added before the hot air treatment. In this case, the external addition conditions were a rotation speed of 3000 rpm and a treatment time of 2 minutes. Next, the magnetic toner particles externally added before the hot air treatment are subjected to surface modification by Meteole Inbo (manufactured by Nippon Pneumatic Industry Co., Ltd.), which is a device for modifying the surface of the magnetic toner particles by blowing hot air. It was. The conditions for the surface modification were a raw material supply rate of 2 kg / hr, a hot air flow rate of 700 L / min, and a discharge hot air temperature of 300 ° C. Table 3 shows the physical properties of the magnetic toner particles 11 obtained by the hot air treatment.

<Production Example of Toner 1 for Example>
The magnetic toner particles 1 obtained in the production example of the magnetic toner particles 1 were externally mixed using the apparatus shown in FIG.
In the present embodiment, the apparatus shown in FIG. 4 uses an apparatus in which the diameter of the inner peripheral portion of the main casing 1 is 130 mm and the volume of the processing space 9 is 2.0 × 10 ⁻³ m ^3. The rated power was 5.5 kW, and the shape of the stirring member 3 was that shown in FIG. Then, the overlap width d of the stirring member 3a and the stirring member 3b in FIG. 5 is 0.25D with respect to the maximum width D of the stirring member 3, and the clearance between the stirring member 3 and the inner periphery of the main body casing 1 is 3.0 mm. .
In the apparatus configuration described above, 100 parts by mass of the magnetic toner particles 1 and 0.70 parts by mass of the silica fine particles 4 were put into the apparatus shown in FIG.
After introducing the magnetic toner particles and silica fine particles, premixing was performed in order to uniformly mix the magnetic toner particles and silica fine particles. The premixing conditions were such that the power of the drive unit 8 was 0.10 W / g (the rotational speed of the drive unit 8 was 150 rpm) and the processing time was 1 minute.
After the pre-mixing, an external additive mixing process was performed. The external mixing process conditions are such that the outermost end peripheral speed of the stirring member 3 is adjusted so that the power of the drive unit 8 is constant at 0.60 W / g (the rotational speed of the drive unit 8 is 1400 rpm), and the processing time For 5 minutes. Table 4 shows the external additive mixing conditions.
After the external addition and mixing treatment, coarse particles and the like were removed with a circular vibration sieve equipped with a screen having a diameter of 500 mm and an opening of 75 μm, to obtain Example Toner 1. Example toner 1 was magnified and observed with a scanning electron microscope, and the number average particle diameter of primary particles of silica fine particles on the surface of the magnetic toner was measured to be 8 nm. Table 4 shows the external addition conditions and physical properties of Example Toner 1.

<Examples of Production of Toners 2 to 22 for Examples and Toners 1 to 11 for Comparative Examples>
In the production example of the toner 1 for the example, the toner 2 for the example was similarly changed except that the type of silica fine particles, the amount of the silica fine particles, the magnetic toner particles, the external addition device, and the external addition conditions shown in Table 4 were changed. To 22 and Comparative toners 1 to 11 were produced. Table 5 shows the physical properties of the obtained toners 2 to 22 for examples and toners 1 to 11 for comparative examples.
Here, when using a Henschel mixer as an external device, Henschel mixer FM10C (Mitsui Miike Chemical Co., Ltd.) was used. In some production examples, the pre-mixing step was not performed.
FIG. 3 shows a plot of coverage X1 and diffusion index of toners 1 to 22 for the examples and toners 1 to 11 for the comparative examples.

<Example 1>
As an image forming apparatus, LBP-3100 (manufactured by Canon Inc.) equipped with a developing sleeve having a small diameter of 10 mm was used, and the printing speed was modified from 16 sheets / minute to 24 sheets / minute. Furthermore, the cartridge was modified to double the toner filling amount.

[Evaluation of durability]
Using the above-described modified machine, using the toner 1 for the example, a horizontal line with a printing rate of 1.5% was applied in a single sheet intermittent mode for 3 days in a high temperature and high humidity environment (32.5 ° C./80% RH). , 15000 sheets (5000 sheets per day) were printed. By evaluating under such conditions, a large amount of stress is received on the magnetic toner, so that the durability performance can be evaluated under more severe conditions.
<Evaluation of image density at the initial stage of durable use under high-temperature and high-humidity environment (HH) (hereinafter referred to as Evaluation 1)>
A solid black image portion is formed in a high temperature and high humidity environment (32.5 ° C./80% RH) at the initial stage of durable use (10th sheet), and the density of this solid black image is measured by a Macbeth reflection densitometer (manufactured by Macbeth). Measured with Judgment criteria for the evaluation of the reflection density of the solid black image (Evaluation 1) are as follows. The evaluation results are shown in Table 6.
A: Very good (above 1.45)
B: Good (from 1.40 to less than 1.45)
C: Normal (from 1.35 to less than 1.40)
D: Inferior (less than 1.35)
In this evaluation, what is considered to be a level having no practical problem is an image density of rank C or higher.

<Evaluation of negative ghost (hereinafter referred to as evaluation 2) and evaluation of blank area (hereinafter referred to as evaluation 3)>
In the durability evaluation, “negative ghost” described later was evaluated at the end of the second day of durable use (when 10,000 sheets were printed). Further, at the end of the third day of durable use (at the time of printing 15,000 sheets), evaluation of “white spot” described later was performed.
As a result, it was possible to obtain an image having a uniform density with almost no ghost and white spots compared to the initial durability.
[Negative Ghost Evaluation]
In the image evaluation regarding the negative ghost, in a high temperature and high humidity environment (32.5 ° C./80% RH), a solid black image band was output for one round of the developing sleeve, and then a halftone image was output. A schematic diagram of the pattern is shown in FIG.
In the evaluation method, the Macbeth density at the place where the solid black image is formed in the first turn (black print portion) and the place where the solid black image is not formed (non-image portion) in the second turn of the developing sleeve of one printed image. The difference in reflection density measured by a reflectometer was calculated as follows. In the negative ghost, the image density of the black print portion in the first turn of the developing sleeve is generally higher than the image density of the non-image portion in the first turn of the developing sleeve. This is a ghost phenomenon in which the shape of the pattern produced in the first round appears as it is. The density difference here was evaluated by measuring the reflection density difference.
“Reflection density difference” = {reflection density (reflection density of the image that was the non-image portion on the first development sleeve)} − {reflection density (reflection of the image that was the black printing portion on the first development sleeve) concentration)}
It is evaluated that the negative ghost is not generated as the reflection density difference is smaller. Table 6 shows the results of evaluation (Evaluation 2) at the end of the second day of durable use (when printing 10,000 sheets), as a comprehensive evaluation of negative ghosts, in four stages A, B, C, and D.
(Evaluation criteria)
A: 0.00 or more and less than 0.10 B: 0.10 or more and less than 0.15 C: 0.15 or more and less than 0.20 D: 0.20 or more In this evaluation, it is considered that there is no practical problem. The image density is higher than C rank.

[Evaluation of white spots]
The evaluation of white spots is that a solid black image is output at high temperature and high humidity (32.5 ° C / 80% RH) at the end of the third day of durable use (when printing 15,000 sheets). A case where the density of the obtained solid black image was 0.3 or more lower than the density of the solid black image output at the initial stage of durable use (10th sheet) was defined as white. The density of the solid black image was measured with a Macbeth reflection densitometer (manufactured by Macbeth). White spots were evaluated according to the following criteria. The evaluation results are shown in Table 6.
A: No white spots (very good)
B: The density of the second half of the image is slightly light but no white spots occur (good)
C: Some white spots (width less than 1.0 cm) are observed in the latter half of the image (no problem in practical use)
D: White spots are observed in the second half of the image (practically problematic)

<Examples 2 to 22>
In Example 1, the same evaluation was performed using the toners 2 to 22 for Examples.
As a result, it was possible to obtain images having no practical problems in all the evaluated items. The evaluation results are shown in Table 6.

<Comparative Examples 1 to 11>
In Example 1, the same evaluation was performed using the toners 1 to 11 for comparative examples. As a result, in all the magnetic toners, “white spots” became a practical problem. The evaluation results are shown in Table 6.

1: main body casing, 2: rotating body, 3, 3a, 3b: stirring member, 4: jacket, 5: raw material inlet, 6: product outlet, 7: central shaft, 8: drive unit, 9: processing space, 10: Rotating body end side surface, 11: Rotating direction, 12: Return direction, 13: Feeding direction, 16: Inner piece for raw material inlet, 17: Inner piece for product outlet, d: Overlapping portion of stirring member interval,
D: width of stirring member, 100: electrostatic latent image carrier (photoconductor), 102: toner carrier, 103: developing blade, 114: transfer member (transfer charging roller), 116: cleaner container, 117: charging member (Charging roller), 121: Laser generator (latent image forming means, exposure device), 123: Laser, 124: Pickup roller, 125: Conveyor belt, 126: Fixing device, 140: Developer, 141: Stirring member

Claims (6)

A magnetic toner containing magnetic toner particles containing a binder resin and a magnetic material, and inorganic fine particles,
The inorganic fine particles are silica fine particles;
The apparent density of the magnetic toner is B (g / cm ³ ), the true density is A (g / cm ³ ), and the tap density measured by tapping 30 times from the state where the apparent density is measured is P (g / cm ³ ), B / A is 0.39 or more and 0.47 or less,
The initial density change rate obtained from the following formula (1) is 14.0 or more and 18.0 or less,
The [total energy amount (mJ) / toner density (g / ml)] of the magnetic toner measured by a powder fluidity measuring apparatus equipped with a rotary propeller blade is 200 mJ / (g / ml). The magnetic toner is 300 mJ / (g / ml) or less.
(Formula 1) Initial density change rate = {1- (B / P)} × 100   The magnetic toner according to claim 1, wherein an average circularity of the magnetic toner is 0.960 or more.   The magnetic toner according to claim 1, wherein a true density of the magnetic toner is 1.50 or more and 1.65 or less.   The magnetic toner according to claim 1, wherein the apparent density of the silica fine particles is 15 g / L or more and 45 g / L or less. The silica fine particles are manufactured by hydrophobizing a silica base material with silicone oil and a silane compound and / or a silazane compound,
When the carbon amount derived from the hydrophobization treatment of the silica fine particles is C, and the carbon amount derived from the hydrophobization treatment of the silica fine particles with the silane compound and / or silazane compound is C (A), the C is It is 4.0 mass% or more and 10.0 mass% or less, The percentage [C (A) / Cx100 (%)] with respect to C of this C (A) satisfy | fills following formula 2. Item 5. The magnetic toner according to any one of Items 1 to 4.
(Formula 2) 5 ≦ C (A) / C × 100 (%) ≦ 20 The magnetic toner contains the silica fine particles in an amount of 0.40 parts by mass to 1.50 parts by mass per 100 parts by mass of the magnetic toner particles, and the surface of the magnetic toner obtained by an X-ray photoelectron spectrometer (ESCA) is used. The coverage X1 with silica fine particles is 50.0 area% or more and 75.0 area% or less, and when the theoretical coverage with the silica fine particles is X2, the diffusion index represented by the following formula 3 satisfies the following formula 4. The magnetic toner according to claim 1, wherein the magnetic toner is a magnetic toner.
(Formula 3) Diffusion index = X1 / X2
(Expression 4) Diffusion index ≧ −0.0042 × X1 + 0.62

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