JP2015125302A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner that gives a good image with stable image density and no fogging regardless of a use environment, and can suppress generation of transfer failure even under such conditions that an image forming apparatus is reduced in size or used for a long period of time.SOLUTION: The toner contains titanium oxide fine particles and silica fine particles as external additives, and the toner contains rutile type titanium oxide fine particles having a major axial diameter of 30 to 500 nm, a minor axial diameter of 10 to 80 nm, and a ratio of major axial diameter/minor axial diameter of 2.0 or more and 8.0 or less, by 0.1 to 1.0 pts.mass per 100 pts.mass of toner particles, with a content ratio of the titanium oxide to silica ranging from 0.4 to 30.0. A coverage X1 of the toner particle surface by the silica fine particles, obtained by X-ray photoelectron spectrometry (ESCA), is 40.0 to 75.0 area%. When a theoretical coverage by the silica fine particles is denoted by X2, X1 and X2 satisfy X1/X2≥-0.0042×X1+0.62. An embedding percentage of the external additives in the toner particles is 25 to 60%.

Description

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

  Conventionally, in an electrophotographic system, an electrostatic latent image carrier (hereinafter also referred to as a photoconductor) generally made of a photoconductive substance is charged by various means, and further exposed to an electrostatic latent image on the surface of the photoconductor. Form. Next, the electrostatic latent image is developed with toner on a toner carrier (hereinafter also referred to as a developing sleeve) to form a toner image, and the toner image is transferred to a transfer material such as paper, and then heat, pressure, and heat and pressure are applied. By fixing the toner image on the transfer material, a copy or print is obtained. At this time, the toner remaining on the photoreceptor without being transferred to the transfer material after the transfer is cleaned by various methods, and the above-described steps are repeated.

In recent years, copying apparatuses and printers using electrophotography have been required to have higher speed, higher image quality, and smaller size, and it has been necessary to provide high-definition images while accelerating the process speed of the apparatus. However, the increase in the load increases the load on the toner, and problems with development performance such as a decrease in image density due to toner deterioration tend to occur.
On the other hand, reducing the diameter of the developing sleeve is an important technique in terms of downsizing. Charging of toner is performed mainly by frictional charging caused by friction between the toner and a frictional charging applying member such as a developing sleeve in a region where the toner is regulated by a toner regulating member (hereinafter referred to as a developing blade).

In particular, in the case of the developing sleeve having a reduced diameter as described above, the developing area of the developing nip portion is narrowed, so that it is difficult for the toner to fly from the developing sleeve. For this reason, a phenomenon called so-called charge-up occurs in which only a part of the toner is excessively charged, which may cause various image defects.
For example, when the toner is charged up, the image density may be lowered due to the toner staying on the developing sleeve, or image defects such as fogging may occur due to uneven charging of the toner. The “fogging” means a phenomenon in which toner adheres to a non-image portion that should originally be white and the density increases.
In addition, if a solid black image is output in a high-temperature and high-humidity environment as an image defect caused by charge-up, the toner sticks to the photoreceptor, and the toner is not efficiently transferred to the transfer material, and the solid black image is blurred white. This will cause an adverse effect on the image (hereinafter referred to as transfer omission).

The reason why transfer loss occurs in a high temperature and high humidity environment is as follows.
There are various electric volume resistance values (hereinafter referred to as volume resistance values) of the transfer material. In particular, in a high-temperature and high-humidity environment, the volume resistance value decreases when the transfer material absorbs moisture. The resistance value tends to increase.
However, for transfer materials with low volume resistance such as moisture-absorbing paper, the transfer current escapes to the body such as a pre-transfer guide member or a fixing device that guides the conveyance upstream of the paper conveyance via the transfer material, In some cases, transfer omission due to insufficient transfer current may occur. On the other hand, if the transfer current is set to a high value in consideration of the current escape of the transfer material with a low volume resistance value, the transfer effect of the transfer material with a high volume resistance value, such as paper that has not absorbed moisture, is caused by an excessive transfer current. Will occur. In particular, in the latter half of durable use in which the durability deterioration of the toner is promoted, the charge of the toner tends to drop, and such transfer omission appears remarkably.
Therefore, a toner that can be efficiently transferred with a transfer material having a low volume resistance value such as moisture-absorbing paper is preferable even when the transfer current is low.

  As means for improving transferability, various methods (Patent Documents 1 to 3) such as external addition of inorganic fine powder to toner particles have been proposed. Patent Document 1 discloses that titanium oxide having a siloxane-bonded silane condensate on the surface is externally added to toner base particles. Patent Document 2 discloses that the liberation rate of external additives such as needle-like titanium oxide and the coverage of the toner particle surface are controlled. Patent Document 3 discloses that the saturation moisture content of the toner is controlled, an external additive having a controlled hydrophobicity is added, and the coverage is controlled.

  Although these technologies certainly have a certain effect on transferability, the problem is not solved in the case where the diameter of the developing sleeve is reduced as described above or in the latter half of durable use in a severer high temperature and high humidity environment, There was still room for improvement.

JP 2010-101953 A JP 2003-207942 A JP 2009-229785 A

An object of the present invention is to provide a toner capable of solving the above problems.
Specifically, it is a toner that can provide a stable image density and a good image without fog regardless of the use environment. Even in the downsizing of an image forming apparatus and severe endurance tests (repeated use tests), there is no transfer omission. An object of the present invention is to provide a toner capable of suppressing the generation.

The present inventors have found that the problem can be solved by defining the externally added state of titanium oxide fine particles and silica fine particles having specific shapes to the toner, and the present invention has been completed. That is, the present invention is as follows.
Toner particles containing a binder resin and a colorant;
Titanium oxide fine particles and silica fine particles as external additives,
A toner having
The titanium oxide fine particles are:
The major axis diameter is 30 nm or more and 500 nm or less,
The minor axis diameter is 10 nm or more and 80 nm or less,
Rutile-type titanium oxide fine particles having a major axis diameter / minor axis diameter ratio of 2.0 or more and 8.0 or less,
The titanium oxide fine particle content is 0.1 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the toner particles,
The ratio of the content of the silica fine particles to the content of the titanium oxide fine particles in the toner is 0.4 or more and 30.0 or less, and the surface of the toner particles obtained by an X-ray photoelectron spectrometer (ESCA) The coverage X1 by the silica fine particles is 40.0 area% or more and 75.0 area% or less,
When the theoretical coverage by the silica fine particles is X2, the diffusion index represented by the following formula 1 satisfies the following formula 2,
The toner according to claim 1, wherein an embedding rate of the external additive in the toner particles is 25% or more and 60% or less.
(Formula 1) Diffusion index = X1 / X2
(Expression 2) Diffusion index ≧ −0.0042 × X1 + 0.62

  According to the present invention, it is a toner capable of obtaining a stable image density and a good image without fog regardless of the use environment, and can suppress the occurrence of transfer omission even in downsizing of an image forming apparatus and severe durability test. It is possible to provide toner.

The figure which shows an example of an image forming apparatus Diagram showing the boundary of the diffusion index 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

Hereinafter, embodiments of the present invention will be described. The toner of the present invention is
Toner particles containing a binder resin and a colorant;
Titanium oxide fine particles and silica fine particles as external additives,
A toner having
The titanium oxide fine particles are:
The major axis diameter is 30 nm or more and 500 nm or less,
The minor axis diameter is 10 nm or more and 80 nm or less,
Rutile-type titanium oxide fine particles having a major axis diameter / minor axis diameter ratio of 2.0 or more and 8.0 or less,
The titanium oxide fine particle content is 0.1 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the toner particles,
The ratio of the content of the silica fine particles to the content of the titanium oxide fine particles in the toner is 0.4 or more and 30.0 or less,
The coverage X1 with the silica fine particles on the surface of the toner particles determined by an X-ray photoelectron spectrometer (ESCA) is 40.0 area% or more and 75.0 area% or less,
When the theoretical coverage by the silica fine particles is X2, the diffusion index represented by the following formula 1 satisfies the following formula 2,
The toner is characterized in that the embedding rate of the external additive in the toner particles is 25% or more and 60% or less.
(Formula 1) Diffusion index = X1 / X2
(Expression 2) Diffusion index ≧ −0.0042 × X1 + 0.62

According to the study by the present inventors, by using the toner as described above, it is a toner that can obtain a stable image density regardless of the use environment and a good image without fogging, and downsizing the image forming apparatus. In addition, the occurrence of transfer omission can be suppressed even in a severe durability test.
Here, it is considered that the problem of transfer omission occurs due to the following causes.

A region where the developing sleeve and the developing blade are rubbed is referred to as a blade nip. According to a long-term durability test, the toner is stressed by rubbing at the blade nip, and the external additive is embedded, resulting in a change in toner physical properties such as fluidity in the early and late durability, resulting in "toner deterioration". . Further, when the developing sleeve is reduced in size in response to downsizing, charged-up toner is likely to be generated, and charging is likely to be uneven.
As a result, for example, not only image defects such as fogging on non-image areas are likely to occur, but also various problems are likely to occur due to increased adhesion between the toner and other members. For example, when the charged-up toner stays on the developing sleeve, the image density tends to decrease.

  In addition, as described above, the toner deteriorated by stress due to long-term durability has poor fluidity, and therefore poor circulation in the blade nip, and the entire toner is not easily frictionally charged. At this time, the charged-up toner tends to increase the adhesion force with the photoreceptor. Further, when image output is performed on a transfer material having a low volume resistance value such as moisture-absorbing paper in a high-temperature and high-humidity environment, the transfer current escapes, so the toner is very difficult to transfer, and transfer omission occurs.

  In order not to cause such problems, it is important to suppress the deterioration of the toner, at the same time, suppress the charge-up, and reduce the adhesion between the photosensitive member and the toner. For this purpose, it is important to first contain silica fine particles as an external additive and to make the coverage X1 40.0 area% or more and 75.0 area% or less. Furthermore, when the theoretical coverage ratio X2 is set, it is important to control the diffusion index (= X1 / X2) within a specific range.

The number average particle diameter of primary particles of silica fine particles is preferably 5 nm or more and 20 nm or less, more preferably 5 nm or more and 15 nm or less, and further preferably 7 nm or more and 15 nm or less.
The coverage X1 is preferably 45.0 area% or more and 70.0 area% or less, and more preferably 45.0 area% or more and 68.0 area% or less.
Here, when the coverage X1 is less than 40.0 area%, the intended effect of the present invention cannot be obtained. On the other hand, when the coverage X1 exceeds 75.0 area%, the low-temperature fixability may be hindered.
By controlling the coverage X1 and the diffusion index as described above, it is possible to greatly suppress toner deterioration caused by long-term use of the toner.

When the primary particle size of the silica fine particles is relatively small and the number average particle size of the primary particles is less than 5 nm, the silica fine particles are likely to aggregate with each other and also exist as aggregates on the toner particle surface. When the silica fine particles are present as an aggregate, when the durability use test is repeated, the silica fine particles are easily released from the surface of the toner particles due to the rubbing between the toners.
Therefore, even if silica fine particles are added so as to adjust the coverage X1 in the early stage of durable use, the coverage by the silica fine particles tends to decrease in the latter half of durable use. Further, since the aggregate is used, the silica particles are more likely to be embedded in the toner due to the force between the silica particles, and the toner physical properties at the initial stage of durable use and the late stage of durable use are likely to be greatly different and toner deterioration is likely to occur.

On the other hand, in the present invention, the silica fine particles can be highly uniformly diffused on the surface of the toner particles by simultaneously controlling the coverage X1 and the diffusion index.
In this case, since the silica fine particles are attached to the surface of the toner particles in a state closer to the primary particles, the silica fine particles are hardly detached from the surface of the toner particles even in the durability use test. Further, since the silica fine particles are in a state closer to the primary particles, the probability that the silica fine particles are in contact with each other is reduced, and it is possible to suppress the toner particles from being easily embedded in the toner particles. .

  In the present invention, it is important that the external additive embedding rate in the toner particles is 25% or more and 60% or less. Preferably, it is 30% or more and 55% or less. As described above, by controlling the coverage and the diffusion index and setting the embedding rate within the above range, the adhesion between the photosensitive member and the toner can be reduced for the first time.

The reason for this is not clear, but the present inventors consider as follows.
In order to reduce the adhesion between the photoconductor and the toner, it is very important that an external additive which is an inorganic fine particle is interposed between the photoconductor and the toner particles. As described above, it is considered that the state of the toner particle surface is made more uniform by embedding the external additive highly uniformly diffused in a specific state. As a result, it is considered that the adhesion between the toner and the photoconductor can be reduced because the probability that the external additive intervenes when the toner and the photoconductor are in contact with each other can be maximized.

For example, even if only the embedding rate is controlled in the state of an aggregate, some external additives in the aggregate are completely buried or some external additives are not buried at all. Will be.
As a result, the portion that is not buried moves on the surface of the toner particles, and the portion where the external additive is not attached is exposed, so that the probability that the portion is not in direct contact with the photoreceptor increases. As a result, the adhesion between the photoconductor and the toner cannot be reduced.

On the other hand, as in the present invention, even when the covering ratio is above a certain level and the diffusion index is controlled, if the embedding ratio of the external additive is less than 25%, the share of the toner is applied in the durability use test. As a result, the external additive is easily detached, and a portion where the photoreceptor and the toner particles are in direct contact is likely to appear.
On the contrary, when the embedding rate of the external additive exceeds 60%, the circulation property of the toner tends to be lowered, and once there is a portion where the toner particles and the photoreceptor are in direct contact, the toner does not rotate. In some cases, the external additive cannot intervene and it is difficult to separate the toner from the photoreceptor.
The coverage and diffusion index will be described in detail later.

Further, it is important that the toner of the present invention contains fine titanium oxide particles, the fine titanium oxide particles have a rutile structure, and the major axis diameter and minor axis diameter are in a specific range.
By adding titanium oxide fine particles having a specific structure and shape in a state where silica fine particles are highly uniformly diffused, the present inventors can highly uniformly diffuse titanium oxide fine particles on the toner particle surface. I found out. As a result, the effect of suppressing the charge-up of the toner by the titanium oxide fine particles can be sufficiently exerted, the adhesion force between the toner and the photoreceptor can be reduced, and the transfer omission on the absorbent paper can be suppressed in a high temperature and high humidity environment. At the same time, it was found that remarkable effects can be obtained.
In particular, when the silica fine particles are in an aggregated state, the silica fine particles adhere around the titanium oxide fine particles, and thus it is difficult to sufficiently exert the toner charge-up suppressing effect.

As described above, by highly uniformly diffusing the two types of inorganic fine particles, the titanium oxide fine particles adhere to the surface of the toner particles in a highly uniformly diffused state, so that charge-up can be effectively suppressed.
Then, for example, even in image formation using a transfer material having a low volume resistance value such as moisture absorbent paper after long-term durability use in a high-temperature and high-humidity environment, the toner can be appropriately charged throughout the developing sleeve. And transfer omission can be suppressed. In this case, the effect of suppressing the charge-up can be sufficiently exhibited, and problems caused by the charge-up of the toner can be suppressed.

By simultaneously controlling the coverage ratio, diffusion index, and external additive embedding ratio, it is possible to suppress toner deterioration, simultaneously suppress charge-up, and reduce the adhesion between the photoreceptor and the toner. For the first time.
In the present invention, the titanium oxide fine particles have a major axis diameter of 30 nm or more and 500 nm or less, a minor axis diameter of 10 nm or more and 80 nm or less, and a ratio of major axis diameter / minor axis diameter of 2.0 or more and 8.0 or less. It is important to be. The major axis diameter is preferably 30 nm to 300 nm, more preferably 30 nm to 150 nm. The minor axis diameter is preferably 10 nm or more and 50 nm or less. The ratio of major axis diameter / minor axis diameter is preferably 2.5 or more and 8.0 or less.
By being in this range, since the titanium oxide fine particles are not easily embedded in the toner even in the durability use test, the charge-up suppressing effect is easily obtained even in the latter half of the durability use.

When the major axis diameter is less than 30 nm or the minor axis diameter is less than 10 nm, the titanium oxide fine particles are easily embedded in the toner, the spacer effect is hardly exhibited, and the effect of suppressing transfer omission in the latter half of the endurance use is hardly obtained.
Further, when the major axis diameter exceeds 500 nm or the minor axis diameter exceeds 80 nm, the release of titanium oxide fine particles from the toner becomes remarkable, and it is difficult to obtain a sufficient charge-up suppressing effect.
When the ratio of the major axis diameter / minor axis diameter is smaller than 2.0, the contact area with the toner particles is small because it is nearly spherical, and the effect of adhesion of the toner tends to be small, and it is easy to release from the toner. Become.
On the other hand, when the ratio of the major axis diameter / minor axis diameter is larger than 8.0, the shape of the titanium oxide fine particles becomes extremely rod-shaped or needle-shaped, and the contact area with the toner or other external additives becomes large. As a result, the spacer effect tends to be small and the durability tends to deteriorate.

In the present invention, it is important that the titanium oxide fine particles are of the rutile type.
Titanium oxide includes a rutile type and an anatase type crystal system. Of these, anatase-type titanium oxide has a volume resistance of about 10 ⁷ Ω · cm, which is generally low. Therefore, especially in a high-temperature and high-humidity environment, the leakage of triboelectric charge tends to be quick, and in terms of stabilizing triboelectric charging. Not enough. Rutile titanium oxide contrast, since the volume resistivity is as high as about ^{10 10 Ω · cm~10 18 Ω ·} cm, acts very effectively in terms of stabilizing the triboelectric charge quantity.

In general, titanium oxide is known to have several peaks in X-ray diffraction. It is known that when the titanium oxide crystal system is anatase type, it has a characteristic and large peak around 2θ = 25.3, and when it is rutile type, it has a characteristic big peak around 2θ = 27.5. Identification is possible.
Although the raw material and manufacturing method of the rutile-type titanium oxide fine particles used in the present invention are not particularly limited, manufacturing examples are shown below.

  Slurry metatitanic acid is produced by hydrolyzing a dispersion obtained by using ilmenite as a starting material and decomposing it with sulfuric acid. After adjusting the pH of this metatitanic acid slurry, it is filtered, fired and crushed to obtain titanium oxide. While dispersing the obtained titanium oxide in the solution, a hydrophobizing agent is added dropwise and reacted. A rutile type titanium oxide can be obtained by performing a filtration, a heat processing, and a crushing process for this.

  The surface of rutile-type titanium oxide fine particles is preferably treated with a hydrophobizing agent. Examples of the hydrophobic treatment agent that can be preferably used in the present invention include silicone oil and silicone varnish. Among them, a silane coupling agent or a self-crosslinking agent such as methyl hydrogen type silicone oil is preferable for durability stability.

Particularly preferably used is a silane coupling agent, which has the general formula RmSiYn.
R: alkoxy group
M: integer from 1 to 3
Y: hydrocarbon group including alkyl group, vinyl group, glycidoxy group, methacryl group N: an integer of 1 to 3
For example, the following may be mentioned. Vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxy Silane coupling agents such as silane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, octyltrimethoxysilane, octyltriethoxysilane.

The treatment amount of the hydrophobizing agent is 1 part by mass to 50 parts by mass, preferably 3 parts by mass to 40 parts by mass with respect to 100 parts by mass of the titanium oxide fine particles, and the degree of hydrophobicity is 20% to 98%, preferably 30. % To 90%, more preferably 40% to 80%.
When the degree of hydrophobicity is less than 20%, the decrease in charge amount due to long-term standing in a high-temperature and high-humidity environment becomes large, which may lead to a decrease in developability. On the other hand, if the degree of hydrophobicity exceeds 98%, it becomes difficult to control the charge of titanium oxide itself, and as a result, the toner may be charged up under low humidity.

In the present invention, it is important that the titanium oxide fine particles are contained in an amount of 0.1 to 1.0 part by mass per 100 parts by mass of the toner. More preferably, it is 0.1 to 0.6 parts by mass.
When the amount is less than 0.1 parts by mass, it is difficult to sufficiently obtain the effect of suppressing the charge-up, and it is particularly difficult to suppress transfer deterioration due to durability. When the amount is more than 1.0 part by mass, contamination of the member due to an increase in the amount released from the toner particles tends to occur, and the low-temperature fixability may be lowered.

In the present invention, it is important that the ratio of the content of the silica fine particles to the content of the titanium oxide fine particles in the toner is 0.4 or more and 30.0 or less. More preferably, it is 0.7 or more and 20.0 or less.
When the content ratio of the silica fine particles is smaller than 0.4, the titanium oxide fine particles are excessive with respect to the silica fine particles, and thus it is difficult to control the embedding rate with the external additive.
On the other hand, when the content ratio of the silica fine particles is larger than 30.0, the titanium oxide fine particles are too small with respect to the silica fine particles, so that it is difficult to obtain the effect of suppressing the charge-up.

Furthermore, the liberation rate of the titanium oxide fine particles is preferably 50% or less, more preferably 30% or less, and still more preferably 20% or less. When the liberation rate is within this range, the effect of suppressing the charge-up is easily exhibited, and the effect of reducing the adhesion force with the photoreceptor is easily obtained. In addition, although the detail of the measuring method of the release rate of titanium oxide microparticles | fine-particles is mentioned later, it is a release rate when it was made to forcibly release in aqueous solution halfway. The embedding rate of the external additive described above contributes to both the silica fine particles and the titanium oxide fine particles, and is not directly related to the release rate of the titanium oxide fine particles.
Examples of means for controlling the liberation rate of the titanium oxide fine particles within the above range include adjustment of power and treatment time during external addition mixing treatment. The rate of liberation can be increased by reducing the power during external addition or by shortening the treatment time. Moreover, the liberation rate can be lowered by increasing the power during the external addition mixing process or by increasing the processing time.

In the present invention, as described above, it is possible to suppress toner deterioration by controlling the coverage and diffusion index. For example, the number of printed sheets is increased by increasing the amount of toner filling. In some cases, the toner may be deteriorated.
In order for the uniform charging and suppression of charge-up as described so far to be properly performed even when the toner deteriorates, the friction at the blade nip is reduced to a single toner even in the end of durable use. It is important that the toner be easily loosened as is done.
The above-described coverage and diffusion index are closely related to this “phenomenon in which the toner is easy to loosen one by one even when the toner deteriorates”.

Next, in the toner of the present invention, the “external addition state of silica fine particles” is defined as follows.
In the toner of the present invention, the coverage X1 with silica fine particles on the surface of the toner particles determined by an X-ray photoelectron spectrometer (ESCA) is 40.0 area% or more and 75.0 area% or less. Further, the toner is characterized in that the diffusion index represented by the following formula 1 satisfies the following formula 2 when the theoretical coverage by silica fine particles is X2.
(Formula 1) Diffusion index = X1 / X2
(Expression 2) 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 40.0 area% or more and 75.0 area% or less, the fluidity and charging property of the toner can be controlled to be in a good state through the durability use test. When the coverage X1 is less than 40.0 area%, it is not possible to obtain sufficient ease of toner loosening described later. For this reason, depending on the evaluation conditions and environment, the toner is likely to deteriorate and the fluidity deteriorates.

On the other hand, the theoretical coverage X2 by the silica fine particles is calculated from the following formula 4 using the number of parts by mass of the silica fine particles per 100 parts by mass of the toner particles, the particle size of the silica fine particles, and the like. This indicates the ratio of the area that can theoretically cover the toner particle surface.
(Equation 4) Theoretical coverage x2 (area%) = 3 ^1/2 / (2Π) × (dT / dA) × (ρT / ρT) × C × 100
dA: number average particle diameter of silica fine particles (d1)
dA: Toner weight average particle diameter (d4)
ρa: true specific gravity of silica fine particles ρt: true specific gravity of toner C: mass of silica fine particles / mass of toner (= mass part of silica fine particles / (mass part of silica fine particles + 100)

The embedding rate of the external additive is calculated by the following formula.
(Formula 5) Embedding ratio of external additive (%) = 100− (Bt−Bm) / Br × 100
Bt: BET of toner
Bm: BET of toner particles
Br: Theoretical value of BET that increases when an external additive is simply added to the toner (BET is the specific surface area (m ² / g) by nitrogen adsorption measured by the BET method)
(Formula 6) Br = [(BET of external additive 1 (B1) × parts by mass of external additive 1/100) + (BET of external additive 2 (B2) × parts by mass of external additive 2/100) + ... (BET of external additive n (Bn) x number of parts by mass of external additive N / 100)]
(In the present invention, since silica fine particles and titanium oxide fine particles are used as the external additive, the BET and the parts by mass are used as the external additives 1 and 2, respectively.)
The specific surface area by nitrogen adsorption measured by the BET method of the external additive is measured according to JIS Z8830 (2001). The measuring device will be described later.

The physical meaning of the diffusion index represented by the above formula 1 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 toner particle surface. 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 fine particles. On the other hand, when the silica fine particles are present on the surface of the toner particles as aggregates, 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 an aggregate.

  In the present invention, it is important that the diffusion index is in the range represented by the above formula 2, and this range is considered to be larger than that of the toner manufactured by the conventional technique. A large diffusion index indicates that among the silica fine particles on the toner particle surface, the amount existing as an aggregate is small and the amount existing as a primary particle is large. As described above, the upper limit of the diffusion index is 1.

The present inventors have found that when the coverage X1 and the diffusion index satisfy the range represented by Formula 2 at the same time, the ease of toner loosening during pressing can be greatly improved.
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, it was also clarified that when the ease of loosening was measured while applying pressure, a more remarkable difference was 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 the diffusion index is very important in addition to the coverage ratio X1 in order to more precisely control the ease of toner loosening during pressurization.
Although the details of the reason why the ease of loosening of the toner is improved when the coverage ratio X1 and the diffusion index satisfy the range represented by Formula 2 at the same time are not understood, the present inventors presume 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 aggregates, the influence of meshing becomes too great, and it becomes difficult to loosen the toners quickly.
In particular, when the toner deteriorates, the silica particles are buried in the toner particle surface, and the fluidity of the toner decreases. At that time, it is presumed that the influence of meshing between the silica fine particles present as aggregates not buried is increased, and the ease of loosening of the toner is hindered.

In the 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 toners to bite into each other. Very easy to loosen into grains. That is, it has become possible to dramatically improve “easiness of toner loosening” that has been difficult only by controlling the conventional coverage X1.
Therefore, in the conventional toner, the toner deteriorated by the stress has poor circulation in the blade nip, and the entire toner is not easily frictionally charged, and the transfer residual toner tends to increase. The problem was solved with toner.

That is, in the toner of the present invention, deterioration is suppressed, and at the same time, even when the toner is deteriorated, the ease of loosening of the toner can be maintained, and at the same time, adhesion to the developing blade and the developing sleeve is reduced. Therefore, the toner circulates well in the blade nip.
As a result, the entire toner is properly charged, and various problems associated with uneven charging and charge-up can be greatly improved.
The boundary line of the diffusion index in the present invention is a function with the coverage ratio X1 as a variable in the range where the coverage ratio X1 is 40.0 area% or more and 75.0 area% or less. The calculation of this function was 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 is a graph plotting the relationship between the coverage ratio X1 and the diffusion index by producing a toner in which the coverage ratio X1 is arbitrarily changed by changing the amount of silica fine particles to be added using three types of external additive mixing conditions. It is. Of the toners plotted in this graph, it was found that the toner plotted in the region satisfying the expression 2 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 toner at the time of pressurization, it is better that the amount of the silica fine particles present as the secondary particles is small, but the influence of the coverage X1 is not a little. As the coverage X1 increases, the ease of loosening of the 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 important to control the diffusion index according to the coverage X1.
When the diffusion index is in the range of Equation 3 shown below, the amount of silica fine particles present as an aggregate increases, and it is difficult to suppress toner deterioration and to sufficiently improve the ease of toner loosening. The effects intended by the present invention cannot be sufficiently exhibited.
(Formula 3) Diffusion index <−0.0042 × X1 + 0.62

As described above, even in a high-temperature and high-humidity environment, it is possible to suppress the occurrence of transfer omission due to the control of the externally added state such as the coverage ratio, diffusion index, and embedding rate, and the synergistic effect of specific titanium oxide fine particles. The present inventors consider that this is caused.
Examples of the binder resin used in the toner of the present invention include vinyl resins, polyester resins, epoxy resins, and polyurethane resins. It does not specifically limit and these conventionally well-known resin can be used. Among these, it is preferable to contain a polyester resin or a vinyl resin from the viewpoint of achieving both chargeability and fixability.

Specific examples and compositions of the polymerizable monomer for the polyester resin are as follows.
Examples of the divalent alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1, 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and bisphenol represented by formula (A) and derivatives thereof;

（式中、Ｒはエチレンまたはプロピレン基であり、Ｘ，Ｙはそれぞれ０以上の整数であり、かつ、Ｘ＋Ｙ平均値は０〜１０である。）
また（Ｂ）式で示されるジオール類；

(In the formula, R is an ethylene or propylene group, X and Y are each an integer of 0 or more, and the average value of X + Y is 0 to 10.)
And diols represented by the formula (B);

（式中、Ｘ’，Ｙ’は、０以上の整数であり、かつ、Ｘ’＋Ｙ’の平均値は０〜１０である。）が挙げられる。

(Where X ′ and Y ′ are integers of 0 or more, and the average value of X ′ + Y ′ is 0 to 10).

  Examples of the divalent acid component include benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof, lower alkyl esters; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid. Acids or anhydrides thereof, lower alkyl esters; alkenyl succinic acids or alkyl succinic acids such as n-dodecenyl succinic acid and n-dodecyl succinic acid, or anhydrides, lower alkyl esters thereof; fumaric acid, maleic acid, citraconic acid, itaconic acid Dicarboxylic acids such as unsaturated dicarboxylic acids or anhydrides thereof, lower alkyl esters;

In addition, a trivalent or higher alcohol component or a trivalent or higher acid component that functions as a crosslinking component may be used alone or in combination.
Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene, etc. Is mentioned.
Examples of the trivalent or higher polyvalent carboxylic acid component in the present invention include trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5, 7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene Carboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empole trimer acid, and anhydrides and lower alkyl esters thereof; tetracarboxylic acid represented by formula (C) etc,

（式中Ｘは炭素数３以上の側鎖を１個以上有する炭素数５〜３０のアルキレン基又はアルケニレン基）
及びこれらの無水物、低級アルキルエステル等の多価カルボン酸類及びその誘導体が挙げられる。
アルコール成分の含有量は、通常４０〜６０モル％、好ましくは４５〜５５モル％である。また、酸成分の含有量は、通常６０〜４０モル％、好ましくは５５〜４５モル％である。
該ポリエステル樹脂は通常一般に知られている縮重合によって得られる。

(Wherein X is an alkylene group or alkenylene group having 5 to 30 carbon atoms having one or more side chains having 3 or more carbon atoms)
And polyhydric carboxylic acids such as anhydrides and lower alkyl esters thereof and derivatives thereof.
Content of an alcohol component is 40-60 mol% normally, Preferably it is 45-55 mol%. Moreover, content of an acid component is 60-40 mol% normally, Preferably it is 55-45 mol%.
The polyester resin is usually obtained by a generally known condensation polymerization.

Further, the binder resin may contain a vinyl resin.
Examples of the polymerizable monomer (vinyl monomer) for producing the vinyl resin include the following.
Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethyl Styrene such as styrene, pn-butyl styrene, p-tert butyl styrene, pn hexyl styrene, pn octyl styrene, pn nonyl styrene, pn decyl styrene, pn dodecyl styrene and derivatives thereof Styrene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene and isoprene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl acetate; Vinyl such as vinyl propionate and vinyl benzoate Stealth; methyl methacrylate, ethyl methacrylate, propyl methacrylate, nbutyl methacrylate, isobutyl methacrylate, n octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylamino methacrylate Α-methylene aliphatic monocarboxylic acid esters such as ethyl and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic Acrylic acid esters such as 2-ethylhexyl acid, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ether, vinyl ethyl ether, Vinyl ethers such as vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; n-vinyl compounds such as n-vinyl pyrrole, n-vinyl carbazole, n-vinyl indole and n-vinyl pyrrolidone. Vinyl naphthalenes; and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

In addition, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid, mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride, etc. Unsaturated dibasic acid anhydride; maleic acid methyl half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, Alkenyl succinic acid half ester, fumaric acid methyl half ester, mesaconic acid methyl half ester unsaturated dibasic acid half ester; dimethylmaleic acid, dimethyl fumaric acid unsaturated dibasic acid ester; acrylic acid, meta Α, β-unsaturated acids such as rillic acid, crotonic acid and cinnamic acid; α, β-unsaturated acid anhydrides such as crotonic acid anhydride and cinnamic acid anhydride, the α, β-unsaturated acid and lower fatty acids And monomers having a carboxyl group such as alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, acid anhydrides and monoesters thereof.
Further, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1) -Methylhexyl) Monomers having a hydroxy group such as styrene.

  In the toner of the present invention, the vinyl resin of the binder resin may have a crosslinked structure crosslinked with a crosslinking agent having two or more vinyl groups. Examples of the crosslinking agent used in this case include divinylbenzene and divinylnaphthalene as aromatic divinyl compounds; examples of diacrylate compounds linked by an alkyl chain include ethylene glycol diacrylate and 1,3-butylene glycol diene. Acrylate, 1,4-butanediol diacrylate, 1,5-pentanediol acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and those obtained by replacing acrylate of the above compounds with methacrylate Examples of diacrylate compounds linked by an alkyl chain containing an ether bond include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, poly Tylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and the above compounds in which acrylate is replaced with methacrylate; chain containing aromatic group and ether bond Examples of diacrylate compounds include polyoxyethylene (2) -2,2-bis (4hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4hydroxyphenyl) propanedi Examples include acrylate and those obtained by replacing acrylate of the above compound with methacrylate; examples of polyester-type diacrylate compounds include trade name MANDA (Nippon Kayaku).

Examples of the polyfunctional cross-linking agent include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, and those obtained by replacing the acrylate of the above compounds with methacrylate; And allyl cyanurate and triallyl trimellitate.
These crosslinking agents can usually be used in an amount of 0.01 to 10 parts by mass (preferably 0.03 to 5 parts by mass) with respect to 100 parts by mass of monomer components other than the crosslinking agent.
Among these crosslinkable monomers, those which are preferably used in the binder resin from the viewpoint of fixability and offset resistance are bonded with aromatic divinyl compounds (particularly divinylbenzene), chains containing aromatic groups and ether bonds. And diacrylate compounds.

  Examples of the polymerization initiator used when producing a vinyl resin as a binder resin include 2,2′-azobisisobutyronitrile and 2,2′-azobis (4-methoxy-2,4-dimethyl). Valeronitrile), 2,2′-azobis (-2,4-dimethylvaleronitrile), 2,2′-azopis (-2methylbutyronitrile), dimethyl-2,2′-azobisisoptylate, 1 , 1′-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyronitrile, 2,2′-azobis (2,4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl -4-methoxyvaleronitrile, 2,2-azobis (2-methylpropane), methyl ethyl ketone peroxide, acetylacetone peroxide, cyclo Ketone peroxides such as xanone peroxide, 2,2-bis (t-butylperoxy) butane, t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroper Oxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide, decanoyl peroxide Oxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-trioyl peroxide, di-isopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, -N-propyl peroxydicarbonate, di-2-ethoxyethyl peroxycarbonate, dimethoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, t-butyl Peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate Eight, t-butyl peroxyisopropyl carbonate, di-t-butyl peroxyisophthalate, t-butyl peroxyallyl carbonate, t-amyl peroxy 2-ethylhexanoate, di-t-butyl peroxyhexaha Mud terephthalate, di -t- butyl peroxy azelate and the like.

The binder resin according to the present invention has a glass transition temperature (Tg) of usually 45 ° C. or higher and 70 ° C. or lower, preferably 50 ° C. or higher and 70 ° C. or lower, from the viewpoint that both low-temperature fixability and storage stability are easily achieved. .
When Tg is less than 45 ° C., storage stability tends to deteriorate. Moreover, when Tg is higher than 70 ° C., the low-temperature fixability tends to be deteriorated.

The toner particles of the present invention contain a colorant. Examples of the colorant preferably used in the present invention include the following.
Examples of organic pigments or organic dyes as cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds.
Examples of the organic pigment or organic dye as the magenta colorant include the following. Condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds.

Examples of the organic pigment or organic dye as the yellow colorant include compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.
Examples of the black colorant include carbon black, the above-described yellow colorant, magenta colorant, and cyan colorant that are toned to black.
When using a colorant, it is preferably used by adding 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer or binder resin.

The toner particles of the present invention can contain a magnetic material. In the present invention, the magnetic material can also serve as a colorant.
Examples of the magnetic material used in the present invention include iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel, or these metals aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, Examples include alloys of metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These magnetic materials have a number-based average particle size of 2 μm or less, preferably 0.05 to 0.5 μm. Further, the magnetic characteristics when 795.8 kA / m is applied are coercive force: 1.6 to 12.0 kA / m, saturation magnetization: 50 to ²⁰⁰ Am ² / kg (preferably 50 to 100 Am ² / kg), and residual magnetization: The thing of 2-20 Am < ² > / kg is preferable.

In the toner of the present invention, the content of the magnetic substance is usually 35% by mass or more and 50% by mass or less, and preferably 40% by mass or more and 50% by mass or less.
If it is less than 35% by mass, the magnetic attractive force with the magnet roll in the developing sleeve tends to decrease, and the fog tends to deteriorate.
On the other hand, when it exceeds 50 mass%, the density tends to decrease due to a decrease in developability.

  Note that the content of the magnetic substance in the toner can be measured using a thermal analyzer, TGA7, manufactured by PerkinElmer. In the measurement method, the toner is heated from room temperature to 900 ° C. at a temperature rising rate of 25 ° C./min in a nitrogen atmosphere, and the weight loss from 100 ° C. to 750 ° C. is defined as the mass of the component excluding the magnetic substance from the toner. The remaining mass is the amount of magnetic material.

The magnetic material used in the toner of the present invention can be produced, for example, by the following method. An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equivalent to or greater than the iron component to the ferrous salt aqueous solution. Air is blown in while maintaining the pH of the prepared aqueous solution at pH 7 or higher, and ferrous hydroxide is oxidized while heating the aqueous solution to 70 ° C. or higher to first produce a seed crystal that becomes the core of magnetic iron oxide. .
Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. While maintaining the pH of the solution at 5 to 10, the reaction of ferrous hydroxide proceeds while blowing air to grow magnetic iron oxide with the seed crystal as the core. At this time, it is possible to control the shape and magnetic characteristics of the magnetic material by selecting an arbitrary pH, reaction temperature, and stirring conditions.
As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 5. A magnetic powder can be obtained by filtering, washing, and drying the magnetic material thus obtained by a conventional method.

In the present invention, when a toner is produced by a polymerization method, it is very preferable to subject the surface of the magnetic material to a hydrophobic treatment. When the surface treatment is performed by a dry method, the coupling agent treatment is performed on the magnetic material that has been washed, filtered, and dried. When the surface treatment is performed by a wet method, after the oxidation reaction is completed, the dried product is redispersed and a coupling treatment is performed. Alternatively, after completion of the oxidation reaction, the oxidant obtained by washing and filtering is redispersed in another aqueous medium without drying, and a coupling treatment is performed.
Specifically, a silane coupling agent is added while stirring the redispersion sufficiently, and the temperature is increased after hydrolysis, or the coupling is performed by adjusting the pH of the dispersion to an alkaline region after hydrolysis. . Among these, from the viewpoint of performing a uniform surface treatment, it is preferable to carry out the surface treatment by reslurry as it is without drying after filtration and washing after completion of the oxidation reaction.

  In order to treat the surface of the magnetic material wet, that is, to treat the magnetic material with a coupling agent in an aqueous medium, first, sufficiently disperse the magnetic substance in the aqueous medium so as to be primary particles, so as not to settle and aggregate. Stir with a stirring blade. Next, an arbitrary amount of coupling agent is added to the dispersion, and surface treatment is performed while hydrolyzing the coupling agent. At this time, it is more preferable to perform the surface treatment while sufficiently dispersing so as not to aggregate while using an apparatus such as a pin mill or a line mill while stirring.

  Here, the aqueous medium is a medium containing water as a main component. Specific examples include water itself, water added with a small amount of surfactant, water added with a pH adjuster, and water added with an organic solvent. As the surfactant, nonionic surfactants such as polyvinyl alcohol are preferable. It is preferable to add the surfactant in an amount of 0.1 to 5.0% by mass with respect to water. Examples of the pH adjuster include inorganic acids such as hydrochloric acid. Examples of the organic solvent include alcohols.

Examples of the coupling agent that can be used in the surface treatment of the magnetic material in the present invention include a silane coupling agent and a titanium coupling agent. More preferably used are silane coupling agents, which are represented by the general formula (i).
R _m SIY _n (i)
[Wherein, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a functional group such as an alkyl group, a vinyl group, an epoxy group, or a (meth) acryl group, and n represents 1 to 3] Indicates an integer. However, m + n = 4. ]

  Examples of the silane coupling agent represented by the general formula (i) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, n-phenyl-γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, Vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyl Diethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, trimethylmethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, hydroxypropyl Examples include trimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.

Among these, from the viewpoint of imparting high hydrophobicity to the magnetic material, it is preferable to use an alkyltrialkoxysilane coupling agent represented by the following formula (ii).
_{c p h 2p + 1 -si- (} oc q h 2q + 1) 3 (ii)
[In formula, p shows the integer of 2-20, q shows the integer of 1-3. ]

When p in the above formula is 2 or more, it becomes easy to impart hydrophobicity to the magnetic material. Further, when p is 20 or less, the coalescence of the magnetic materials is easily suppressed. Furthermore, q is preferably 3 or less because the reactivity of the silane coupling agent is easily improved. It is preferable to use an alkyltrialkoxysilane coupling agent in which p in the formula represents an integer of 2 to 20 and q represents an integer of 1 to 3.
When using the said silane coupling agent, it is possible to process independently or to process in combination of several types. When using several types together, you may process separately with each coupling agent, and may process simultaneously.
The total amount of the coupling agent to be used is preferably 0.9 to 3.0 parts by mass with respect to 100 parts by mass of the magnetic substance, and depending on the surface area of the magnetic substance, the reactivity of the coupling agent, etc. It is important to adjust the amount.

In addition, a charge control agent may be added to the toner of the present invention. The toner of the present invention may be either positive or negative, but since the binder resin itself has high negative chargeability, it is preferably a negatively chargeable toner.
For example, organometallic complexes and chelate compounds are effective as negatively charged ones. Examples thereof include monoazo metal complexes; acetylacetone metal complexes; metal complexes of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids and their metals. Examples thereof include salts, anhydrides, esters, and phenol derivatives such as bisphenol.
Preferred examples of the charge control agent for negative charging include SPILON BLACK TRH, T-77, T-95 (Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) S-34, S-44, S-54. , E-84, E-88, E-89 (Orient Chemical Co., Ltd.).

  Examples of those that are controlled to be positively charged include modified products of nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and the like. Onium salts such as phosphonium salts and the like, and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybthenic acid, phosphotungstomolybthenic acid, tannic acid, Lauric acid, gallic acid, ferricyanic acid, ferrocyanic compound, etc.); metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyl Rusuzuboreto, be mentioned, such as organo-tin borate of dicyclohexyl tin borate. These can be used alone or in combination of two or more.

Preferred examples of the charge control agent for positive charging include TP-302, TP-415 (Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) N-01, N-04, N-07, P- 51 (Orient Chemical Co., Ltd.) and Copy Blue PR (Clariant).
These metal complex compounds can be used alone or in combination of two or more. The amount of these charge control agents used is preferably 0.1 to 5.0 parts by mass per 100 parts by mass of the binder resin from the viewpoint of the charge amount of the toner.

In the present invention, hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax are preferably used as the wax because of ease of dispersion in the toner and high releasability. . If necessary, one or two or more kinds of waxes may be used together in a small amount. Examples include the following:
Oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or block copolymers thereof; waxes based on fatty acid esters such as carnauba wax, sazol wax, and montanate wax; and deoxidation The fatty acid esters such as carnauba wax may be partially or wholly deoxidized. Furthermore, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as pracidic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, and seryl alcohol Saturated alcohols such as melyl alcohol; long-chain alkyl alcohols; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; Saturated fatty acid bisamides such as acid amide, ethylene bislauric acid amide, hexamethylene bis stearic acid amide; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, n, n′-dioleoyl Unsaturated fatty acid amides such as dipic acid amide and n, n-dioleyl sebacic acid amide; Aromatic bisamides such as m-xylene bisstearic acid amide and n, n-distearyl isophthalic acid amide; Grafted with fatty acid metal salts such as calcium phosphate, zinc stearate, magnesium stearate (generally called metal soap), and aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid. Examples of waxes include partially esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols, and methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils and the like.

  Moreover, it is preferable that melting | fusing point prescribed | regulated by the maximum endothermic peak temperature at the time of temperature rising measured with the differential scanning calorimeter (DSC) of this wax is 70 to 140 degreeC. More preferably, it is 90 to 135 ° C. When the melting point is 70 ° C. or lower, the viscosity of the toner tends to decrease, and the toner tends to be fused to the electrostatic latent image carrier. On the other hand, when the melting point is 140 ° C. or higher, the low-temperature fixability tends to deteriorate.

The “melting point” of the wax is determined by measuring according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device), DSC-7 (manufactured by Perkin Elmer). The sample to be measured is precisely weighed 5 to 20 mg, preferably 10 mg.
This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rising rate of 10 ° C./min and at normal temperature and humidity in a measurement temperature range of 30 to 200 ° C. Since the maximum endothermic peak is obtained in the temperature range of 40 ° C. to 100 ° C. in the second temperature raising process, the temperature at that time is used as the melting point of the wax.
The amount of the wax is usually 1 to 40 parts by weight, preferably 2 to 30 parts by weight per 100 parts by weight of the binder resin, although it depends on the toner production method.

The silica fine particles used in the present invention are particularly preferably fine particles produced by vapor phase oxidation of a silicon halogen compound, and are referred to as dry process silica or fumed silica. For example, it utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen and hydrogen, and the basic reaction formula is as follows.
SICl ₄ + 2H ₂ +0 ₂ → SiO ₂ + 4HCl
In this production process, it is also possible to obtain composite fine particles of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds. Such composite fine particles can also be used in the present invention.

In the present invention, the number average particle diameter (D1) of the primary particles is preferably 5 nm or more and 20 nm or less, more preferably 5 nm or more and 15 nm or less, and further preferably 7 nm or more and 15 nm or less. When the particle size of the silica fine particles is in the above range, the collision frequency between the toner particles and the silica fine particles is likely to be higher than that between the silica fine particles during the external addition mixing treatment, and the coverage X1, the diffusion index, and the external additive It becomes easy to control the embedding rate of.
The method for measuring the number average particle diameter (D1) of the primary particles of the silica fine particles in the present invention will be described later.

Further, the silica fine particles produced by vapor phase oxidation of the silicon halogen compound are more preferably treated silica fine particles having a hydrophobic surface. The treated silica fine particles are particularly preferably those obtained by treating the silica fine particles so that the degree of hydrophobicity measured by a methanol titration test is in the range of 30-80.
Examples of the hydrophobic treatment method include a method of chemically treating with an organosilicon compound and / or silicone oil that reacts or physically adsorbs with silica fine particles. A preferred method is a method of chemically treating silica fine particles produced by vapor phase oxidation of a silicon halogen compound with an organosilicon compound.

  Examples of the organosilicon compound include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, and bromomethyl. Dimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, Diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divirtetramethyldisiloxane, 1,3 -Diphenyltetramethyldisiloxane and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and one hydroxy group on the silicon atom of the terminal unit. These are used alone or in a mixture of two or more.

  In addition, aminopropyltrimethoxysilane having nitrogen atom, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, monobutylaminopropyl Trimethoxysilano, dioctylaminopropyldimethoxysilane, dibutylaminopropyldimethoxysilane, dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine, trimethoxysilyl-γ-propylbenzylamine Such silane coupling agents may be used alone or in combination. Preferred silane coupling agents include hexamethyldisilazane (hmds).

The silicone oil preferably has a viscosity at 25 ° C. of 0.5 to 10000 mm ² / sec, more preferably 1 to 1000 mm ² / sec, and still more preferably 10 to 200 mm ² / sec. Specific examples include dimethyl silicone oil, methyl fell silicone oil, α-methyl styrene modified silicone oil, chlorophenyl silicone oil, and fluorine modified silicone oil.

  As a method for treating silicone oil, for example, silica fine particles treated with a silane coupling agent and silicone oil are directly mixed using a mixer such as a Henschel mixer; silicone oil is sprayed on the silica fine particles as a base. Or a method in which silicone oil is dissolved or dispersed in a suitable solvent, and then silica fine particles are added and mixed to remove the solvent.

The silica fine particles treated with silicone oil are more preferably heated to 200 ° C. or higher (more preferably 250 ° C. or higher) in an inert gas to stabilize the surface coating after the silicone oil treatment.
The processing amount of the silicone oil is usually 1 to 40 parts by mass, preferably 3 to 35 parts by mass with respect to 100 parts by mass of the silica fine particles. If it is the said range, favorable hydrophobicity will be easy to be obtained.

The silica fine particles used in the present invention preferably have a specific surface area of 20 m ² / g or more and 350 m ² / g or less as measured by a BET method by nitrogen adsorption in order to impart good fluidity to the toner. More preferably, the ^{25 m} 2 / g or more 300 meters ² / g or less. The silica fine particles in the above range are preferably subjected to the hydrophobic treatment. The measurement of the specific surface area measured by the BET method by nitrogen adsorption of external additives such as silica fine particles will be described later.

  The silica fine particles used in the present invention preferably have an apparent density of 15 g / L or more and 50 g / L or less. More preferably, it is 20 g / L or more and 40 g / L or less. The apparent density of the fine silica particles is in the above range, which indicates that the fine silica particles are not densely packed and exist with a lot of air between the fine particles, and the apparent density is very low. For this reason, the toners are less likely to be clogged with each other, and the speed of toner deterioration can be greatly reduced.

Means for controlling the apparent density of the silica fine particles within the above range include the adjustment of the particle size of the silica raw material used for the silica fine particles, the strength of the crushing treatment performed before, during or during the above-described hydrophobization treatment, and the treatment of silicone oil. Adjusting the amount and the like. 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 aggregates contained in the silica fine particles can be loosened into relatively small secondary particles, and the apparent density can be reduced.
Here, the addition amount of the silica fine particles is usually 0.3 parts by mass or more and 3.5 parts by mass or less, preferably 0.3 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the toner particles. is there. When the addition amount of the silica fine particles is within the above range, it is easy to appropriately control the covering rate, the diffusion index, and the embedding rate of the external additive.

As a mixing processing apparatus for externally mixing the silica fine particles, a known mixing processing apparatus can be used, but it is shown in FIG. 3 in that the coverage X1, diffusion index, and external additive embedding rate can be easily controlled. Such an apparatus is preferred.
FIG. 3 is a schematic view showing an example of a mixing treatment apparatus that can be used when externally mixing inorganic fine particles (silica fine particles and titanium oxide fine particles) used in the present invention.
The mixing device is configured to take a share in a narrow clearance portion with respect to the toner particles and the inorganic fine particles, so that the inorganic fine particles adhere to the toner particle surface while loosening the secondary fine particles from the primary particles to the primary particles. Can be made. By loosening the inorganic fine particles into primary particles, the coverage X1, the diffusion index, and the embedding rate of the external additive can be easily controlled within a preferable range.
Further, as will be described later, the coverage X1, diffusion index, and embedding of external additives are easy in that the toner particles and the inorganic fine particles are easily circulated in the axial direction of the rotating body, and are sufficiently uniformly mixed before the fixing proceeds. It is easy to control the rate within a preferable range in the present invention.
In the present invention, a known mixing apparatus (Henschel mixer or the like) can be used as described above. However, as described above, the apparatus has a configuration in which a share is applied to the Henschel mixer or the like as shown in FIG. Therefore, it is easier to control the externally added state of the present invention.
That is, in order to control the coverage X1, the diffusion index, and the embedding rate of the external additive to the preferable ranges in the present invention by using a Henschel mixer that is relatively difficult to take a share without using the apparatus as shown in FIG. Is not preferable because it is difficult to achieve even if the treatment time is remarkably increased while performing multistage external addition.

On the other hand, FIG. 4 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 inorganic fine particle is demonstrated using FIG.3 and FIG.4.
The mixing processing apparatus for externally mixing the inorganic 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 rotating member 2. 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 toner particles and easily adheres to the toner particle surface while loosening the inorganic fine particles from the secondary particles to the primary particles. Therefore, it is preferable to keep it constant and minute.

  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. 3 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 toner particles is appropriately limited. A sufficient impact force is applied to the inorganic fine particles.

  Moreover, it is preferable to adjust the said clearance according to the magnitude | size of a main body casing. By setting the diameter of the inner peripheral portion of the main casing 1 to about 1% or more and 5% or less, a sufficient share can be applied to the inorganic 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 process of the inorganic fine particles in the present invention, the rotating body 2 is rotated by the drive unit 8 using the mixing processing device, and the toner particles and the inorganic fine particles charged into the mixing processing device are stirred and mixed. Inorganic fine particles are externally mixed on the surface of the toner particles.
As shown in FIG. 4, at least a part of the plurality of stirring members 3 is formed as a feeding stirring member 3 a that sends toner particles and inorganic fine particles in one direction in the axial direction of the rotating body as the rotating body 2 rotates. Is done. At least a part of the plurality of stirring members 3 is formed as a return stirring member 3b that returns the toner particles and the inorganic 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. 3, the direction from the raw material inlet 5 toward the product outlet 6 (in FIG. 3). (Right direction) is called “feed direction”.
That is, as shown in FIG. 4, the plate surface of the feeding stirring member 3 a is inclined so as to feed the 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 toner particles and inorganic fine particles in the return direction 12.
Thus, the external addition mixing process of the inorganic fine particles is performed on the surface of the toner particles while repeatedly performing the feeding in the “feeding direction 13” and the feeding in the “returning direction 12”.

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. 4, 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. 4, a total of 12 stirring members 3a and 3b are formed at equal intervals.
Furthermore, in FIG. 4, D shows the width | variety of a stirring member, d shows the space | interval which shows the overlapping part of a stirring member. From the viewpoint of efficiently feeding toner particles and inorganic 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. 4 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.
Thereby, it is possible to efficiently share the inorganic fine particles which 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. 4, if the 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 and the tip blade portion are A paddle structure coupled to the rotating body 2 with a rod-like arm may be used.

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. 3 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 body casing that is provided with a gap between the stirring member 3. 1 Furthermore, it has the jacket 4 which can exist in the inner side of the main body casing 1, and the rotary body end part side surface 10, and can let a cooling medium flow.

Further, the apparatus shown in FIG. 3 discharges the raw material inlet 5 formed on the upper portion of the main casing 1 and the externally mixed toner from the main casing 1 in order to introduce toner particles and inorganic fine particles. In addition, a product discharge port 6 formed in the lower part of the main body casing 1 is provided.
Further, in the apparatus shown in FIG. 3, 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 the toner particles are put into the processing space 9 from the raw material inlet 5. Next, inorganic fine particles are introduced into the treatment space 9 from the raw material inlet 5 and the inner piece 16 for raw material inlet 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.
The order of charging may be such that the inorganic fine particles are first charged from the raw material charging port 5 and then the toner particles are charged from the raw material charging port 5. Further, after the toner particles and the inorganic fine particles are mixed in advance by a mixer such as a Henschel mixer, the mixture may be charged from the raw material charging port 5 of the apparatus shown in FIG.

In the present invention, toner particles, silica fine particles and titanium oxide fine particles may be mixed once, and then silica fine particles may be further added and mixed. The two-stage mixing is preferable in that the coverage X1, the diffusion index, and the embedding rate of the external additive can be easily controlled.
More specifically, controlling the power of the drive unit 8 to be 0.2 W / g or more and 2.0 W / g or less as the external addition mixing processing condition means that the coverage X1, the diffusion index, and the It is preferable for obtaining the embedding rate of the external additive. 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 external additive tends to be embedded too much.
Although it does not specifically limit as processing time, Preferably it is 3 to 10 minutes. When the treatment time is shorter than 3 minutes, the coverage X1 and the diffusion index tend to be low.

The number of rotations of the stirring member during external addition mixing is not particularly limited. In the apparatus in which the volume of the processing space 9 of the apparatus shown in FIG. 3 is 2.0 × 10 ⁻³ m ³ , the rotation speed of the stirring member when the shape of the stirring member 3 is that of FIG. 4 is 800 rpm or more and 3000 rpm. The following is preferable. By being 800 rpm or more and 3000 rpm or less, it becomes easy to obtain the coverage X1, the diffusion index, and the external additive embedding rate specified 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, silica fine particles and titanium oxide fine particles are highly uniformly dispersed on the toner particle surfaces. Therefore, the coverage X1 tends to increase and the diffusion index tends to increase.
More specifically, as premixing 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. 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, if the load power is higher than 0.20 W / g or the processing time is longer than 1.5 minutes as the pre-mixing processing condition, the silica fine particles are fixed on the surface of the toner particles before sufficient uniform mixing is performed. It may be done.

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. 3 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 in this range, 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 toner is discharged from the product discharge port 6. From the obtained toner, coarse particles and the like are separated by a sieve such as a circular vibration sieve as necessary to obtain a toner.

The method for producing the toner particles of the present invention is not particularly limited, and a known method can be used. Although the toner particles can be produced by a pulverization method, the obtained toner particles are generally indefinite shape. For this reason, in order to obtain a physical property having an average circularity of 0.960 or more, it is preferable to perform mechanical / thermal or some special treatment. Therefore, the toner particles of the present invention are preferably produced in an aqueous medium such as a dispersion polymerization method, an association aggregation method, a dissolution suspension method, a suspension polymerization method, and the suspension polymerization method is particularly suitable for the present invention. It is very preferable because it easily satisfies the physical properties.
The toner particles according to the present invention are preferably formed by forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in an aqueous medium, and the polymerizable monomer contained in the particles. It can be obtained by polymerizing the body. As the polymerizable monomer, those described above as the binder resin material can be used.
The toner of the present invention has a weight average particle diameter (D4) of usually 5.0 μm or more and 10.0 μm or less, preferably 6.0 μm or more and 9.0 μm or less, from the viewpoint of a balance between developability and fixability. is there.

In the present invention, the average circularity of the toner particles is preferably 0.960 or more, and more preferably 0.970 or more. When the average circularity of the toner particles is 0.960 or more, the shape of the toner is a sphere or a shape close to this, and it is easy to obtain a uniform triboelectric chargeability with excellent fluidity. Therefore, it is preferable because it becomes easy to maintain high developability even in the latter half of durable use. In addition, toner particles having a high average circularity are preferable because the coverage X1, the diffusion index, and the embedding rate of the external additive can be easily controlled within the scope of the present invention in the external addition mixing process of the inorganic fine particles. .
Further, from the viewpoint of ease of loosening of the toner at the time of pressurization, it is preferable because the meshing effect on the surface shape of the toner particles hardly occurs and the ease of loosening can be further improved. When toner particles are produced in the aqueous medium, it becomes easy to control the average circularity within the above range. In the case of the pulverization method, it is possible to control to the above range by performing a thermal spheronization process, surface modification and fine powder removal.

  In the case of producing by a pulverization method, for example, a binder resin and a colorant and, if necessary, other additives such as a release agent 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 toner particles obtain. 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 toner particles having a preferable average circularity of the present invention, it is preferable to further pulverize by applying heat or to add a mechanical impact force supplementarily. Further, a hot water bath method in which finely pulverized (classified as necessary) 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 type 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 of applying a mechanical impact force to the toner particles by a force such as a compressive force or a frictional force, such as a device such as a mechano-fusion system manufactured by Hosokawa Micron Corporation or a hybridization system manufactured by Nara Machinery Co., Ltd.

In the suspension polymerization method, first, a polymerizable monomer and a colorant (further, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives as necessary) are uniformly dissolved or dispersed 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 simultaneously subjected to a polymerization reaction, whereby a toner having a desired particle size is obtained. Particles are obtained.
The toner particles obtained by this suspension polymerization method (hereinafter also referred to as “polymerized toner particles”) are suitable for the present invention having an average circularity of 0.960 or more because the individual toner particle shapes are substantially spherical. It is easy to obtain toner particles that satisfy physical property requirements. Furthermore, since the toner particles have a relatively uniform charge distribution, an improvement in image quality can be expected.

As the polymerizable monomer constituting the polymerizable monomer composition, known ones can be used in addition to those exemplified as the vinyl monomer. 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 are preferably those described above, azo or diazo polymerization initiators, peroxide polymerization initiators, and the like.
In the suspension polymerization method, the crosslinking agent may be added at the time of the polymerization reaction. is there.
Here, as the crosslinking agent, a compound mainly having two or more polymerizable double bonds is preferred. For example, as described above, an aromatic divinyl compound, a carboxylic acid ester having two double bonds, a divinyl compound, and a compound having three or more vinyl groups are preferable. These can be used alone or as a mixture of two or more.

Hereinafter, the production of toner particles by the suspension polymerization method will be specifically described, but the present invention is not limited thereto. First, the above-mentioned polymerizable monomer and coloring agent are added as appropriate, and the polymerizable monomer composition uniformly dissolved or dispersed by a disperser such as a homogenizer, a ball mill, or an ultrasonic disperser is dispersed. It is granulated by suspending in an aqueous medium containing a stabilizer. 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 an ordinary stirrer to such an extent that the particle state is maintained and particle floating and sedimentation are suppressed.
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 cleaning is easy and adversely affects toner particles. Since it is difficult, it can be preferably used. Examples of such inorganic dispersants include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, hydroxyapatite and other phosphate polyvalent metal salts, carbonates such as calcium carbonate and magnesium carbonate, and calcium metasilicate. Inorganic salts such as calcium sulfate and 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 and 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 toner particles. The toner of the present invention is obtained by externally mixing silica fine particles and strontium titanate fine particles, which are inorganic fine particles, and adhering the toner particles to the surface of the toner particles.
It is also possible to add a classification step to the production process (before mixing the inorganic fine particles) to remove coarse powder and fine powder contained in the toner particles.

Next, an example of an image forming apparatus that can suitably use the toner of the present invention will be specifically described with reference to FIG. In FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier (hereinafter also referred to as a photoconductor), which has a roller-shaped charging member (charging roller) 117 around it, a developing device 140 having a toner carrier 102, a roller-shaped carrier. A transfer member (transfer roller) 114, a waste toner container 116, a fixing device 126, a pickup roller 124, and the like are provided. 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 the laser beam 123 by 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. A part of the toner remaining on the electrostatic latent image carrier is scraped off by the cleaning blade and stored in the waste toner container 116.

Next, it describes regarding the measuring method of each physical property which concerns on this invention.
<Quantification method of silica fine particles>
(1) Determination of the content of silica fine particles in the toner (standard addition method)
3 g of toner is put in an aluminum ring having a diameter of 30 mm, and pellets are produced at a pressure of 10 tons. And the intensity | strength of silicon (Si) is calculated | required by wavelength dispersion type | mold fluorescence X-ray analysis (XRF) (Si intensity | strength -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. To the toner, silica fine particles having a primary particle number average particle diameter of 12 nm are added in an amount of 1.0 mass% with respect to the toner, and then mixed by a coffee mill.
After mixing, pelletization is performed in the same manner as described above, and then the strength of Si is determined 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. Using Si strength-1 to 4, the silica content (% by mass) in the toner is calculated by the standard addition method.

(2) Separation of silica fine particles from toner When the toner contains a magnetic substance, the silica fine particles are quantified through the following steps.
5 g of toner is weighed into a 200 mL plastic cup with a lid using a precision balance, 100 mL of methanol is added, and the mixture is dispersed for 5 minutes with an ultrasonic disperser. Attract the toner with a neodymium magnet and discard the supernatant. After repeating the operation of dispersing with methanol and discarding the supernatant three times, the following materials are added, mixed gently, and then allowed to stand for 24 hours.
・ 10% NaOH 100mL
・ "Contaminone N" (Nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for cleaning precision measuring instruments with pH 7 consisting of organic builder, manufactured by Wako Pure Chemical Industries, Ltd.)
After a few drops, separate 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 strengths -1 to 4 used in the determination of the silica content in the 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, there is a possibility that the tetrahydrofuran insoluble matter in the resin remains. For this reason, it is preferable that the particles B obtained by the above operation are heated to a temperature of 800 ° C. to burn the remaining organic components, and the particles C obtained after the heating are approximated to the magnetic material contained in the toner. be able to.
By measuring the mass of the particles C, the magnetic substance content W (% by mass) in the 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 toner (mass%) − silica content in particles A (mass%)

<Quantitative determination method of titanium oxide fine particles>
Titanium oxide fine particles can be quantified by the standard addition method in the same manner as the silica fine particle quantification method. At this time, fine titanium oxide particles having a major axis diameter of 145 nm and a minor axis diameter of 50 nm were used. It can be quantified by using the intensity of Ti by wavelength dispersive X-ray fluorescence analysis (XRF).

<Measurement method of coverage X1>
The coverage X1 with the silica fine particles on the surface of the toner particles is calculated as follows.
The following apparatus is used under the following conditions, and elemental analysis of the toner particle surface is performed.
・ Measurement 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 conditions: Combined use of neutralization gun and ion gun-Analysis area: 300 x 200 mm
・ Pass Energy: 58.70eV
・ Step size: 1.25eV
・ Analysis software: Maltipak (PHI)

Here, for the calculation of the quantitative value of Si atoms, the peaks of C 1c (BE 280 to 295 eV), O 1S (BE 525 to 540 eV) and Si 2p (BE 95 to 113 eV) are used. It was used. The quantitative value of the Si element obtained here is Y1.
Next, in the same manner as the elemental analysis of the surface of the toner particles described above, the elemental analysis of the silica fine particles is performed, and the quantitative value of the Si element obtained here is Y2.

In the present invention, the coverage X1 with the silica fine particles on the surface of the toner particles 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 surface of the toner particles 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 Co., Ltd.) is added to 100 mL of ion-exchanged water, and dissolved with a 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 (KM Shaker) at 350 reciprocations per minute for 20 minutes. 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 minutes. 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.

<Method for Measuring Toner Weight Average Particle Size (D4)>
The weight average particle diameter (D4) of the toner is calculated as follows (also calculated in the case of toner particles). As the 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 of measurement conditions and analysis of measurement data, 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, a 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 ( The value obtained by using the product) is set. 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 dedicated to 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 solution is placed in a glass 100 mL flat bottom beaker. As a dispersant, “Contaminone N” (a nonionic surfactant, an anionic surfactant, a 10% by weight aqueous solution of a neutral detergent for washing a pH 7 precision measuring instrument comprising an organic builder, Wako Pure Chemical Industries, Ltd. About 0.3 mL of a diluted solution obtained by diluting (made in ()) with ion-exchanged water about 3 times by mass 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 Tetora150” (manufactured by Nikki Bios Co., Ltd.) with an electrical output of 120 W is prepared. To do. About 3.3 liters 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 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 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 the sample stand, the electrolytic solution (5) in which the toner is dispersed is dropped using a pipette, and the measurement concentration is adjusted to about 5%. . 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 statistic (arithmetic average)” screen when the graph / volume% is set with the dedicated software is the weight average particle diameter (D4).

<Measurement method of number average particle diameter (D1) of primary particles of silica fine particles and major axis diameter and minor axis diameter of titanium oxide fine particles>
The number average particle diameter of primary particles of silica fine particles and the major axis diameter and minor axis diameter of titanium oxide fine particles are photographed by Hitachi Ultra High Resolution Field Emission Scanning Electron Microscope S-4800 (Hitachi High-Technologies Corporation). It is calculated from the silica fine particle and titanium oxide fine particle images on the surface of the toner particles. The image capturing conditions of S-4800 are as follows.

(1) Sample preparation A conductive paste is thinly applied to a sample table (aluminum sample table 15 mm × 6 mm), and toner is sprayed thereon. Further, air is blown to remove excess 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 silica fine particles and the major axis diameter and minor axis diameter of the titanium oxide fine particles are calculated using images obtained by observation of the reflected electron image of S-4800. Do it. Since the reflected electron image has less charge-up than the secondary electron image, the particle size can be measured with high accuracy.
Pour liquid nitrogen into the anti-contamination trap attached to the S-4800 enclosure until it overflows, and leave it for 30 minutes. S-4800 “PCSTEM” 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 housing. 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 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 primary particles of silica fine particles and major axis diameter and minor axis diameter of titanium oxide fine particles Drag within the magnification display section of the control panel to set the magnification to 100000 (100k) times To do. 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 average particle size is determined by measuring the particle size of at least 300 silica fine particles on the surface of the toner particles. 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) is obtained.
Similarly, the major axis and the minor axis are obtained by measuring the major and minor axes of at least 300 titanium oxide fine particles on the surface of the toner particles and determining the number average thereof. Further, the major axis diameter / minor axis diameter is obtained by dividing the major axis diameter obtained here by the minor axis diameter.

<Measuring method of average circularity of toner particles>
The average circularity of the toner particles is measured by a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation) under the measurement and analysis conditions during the calibration operation.
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. As a dispersant, “Contaminone N” (a nonionic surfactant, an anionic surfactant, a 10% by weight aqueous solution of a neutral detergent for washing a pH 7 precision measuring instrument comprising an organic builder, Wako Pure Chemical Industries, Ltd. About 0.2 mL of a diluted solution obtained by diluting (made in ()) with ion-exchanged water about 3 times by mass.
Further, about 0.02 g of a measurement sample is added, and a 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 ultrasonic cleaner disperser (for example, “VS-150” (manufactured by Vervo Crea)) having an oscillation frequency of 50 kHz and an electric output of 150 W is used. A fixed amount of ion-exchanged water is added, and about 2 mL of the contamination N is added to the water tank.

For the measurement, the flow type particle image analyzer equipped with “UPlanApro” (magnification: 10 ×, numerical aperture: 0.40) as an objective lens was used, and particle sheath “PSE-900A” (Sysmex Corporation) was used as the sheath liquid. Made). The dispersion prepared in accordance with the above procedure is introduced into the flow type particle image analyzer, and 3000 toner particles are measured in the HPF measurement mode and in the total count mode. Then, the binarization threshold at the time of particle analysis is set to 85%, the analysis particle diameter is limited to the circle equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the 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. The analysis particle size is measured under the measurement and analysis conditions when the calibration certificate is received, except that the equivalent circle diameter is limited to 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 flowing particles 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 peripheral length L, etc. are measured.
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.

<Method for measuring apparent density of silica fine particles>
The apparent density of the 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 the following formula: 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 added) /0.1

<Measurement method of true specific gravity of toner and silica fine particles>
The true specific gravity of the toner and silica fine particles was measured by a dry automatic densimeter autopycnometer (manufactured by Yuasa Ionics Co., Ltd.). 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 specific gravity 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.

<Measurement method of release rate of titanium oxide fine particles>
Preparation of sample Toner before release: Various toners prepared in Examples described later were used as they were.
Toner after release: Weigh 20 g of 2% by weight aqueous solution of neutral detergent for cleaning of pH7 precision measuring instrument consisting of non-ionic surfactant, anionic surfactant and organic builder, into a 50 mL vial. The toner is mixed with 1 g of toner, set in “KM Shaker” (model: V.SX) manufactured by Iwaki Sangyo Co., Ltd., set to speed 50 and shaken for 30 seconds, and then centrifuged (5 rpm at 1000 rpm). The toner and the aqueous solution are separated at a minute) The supernatant is separated, and the precipitated toner is dried by vacuum drying to obtain a sample.
External additive-removed toner: The external additive-removed toner means a state in which an external additive that can be liberated in this test is removed. In the sample preparation method, the toner is put in a solvent that does not dissolve the toner, such as isopropanol, and vibration is applied for 10 minutes with an ultrasonic cleaner. Thereafter, the toner and the solution are separated by a centrifugal separator (1000 rpm for 5 minutes). The supernatant is separated, and the precipitated toner is vacuum-dried to obtain a sample.
With respect to the samples before and after the removal of the free external additive, the titanium oxide fine particles were quantified by using the intensity of Ti by wavelength dispersive X-ray fluorescence analysis (XRF) to determine how much they were released.

(I) Example of equipment used X-ray fluorescence analyzer 3080 (Rigaku Corporation)
Sample press molding machine MAEKAWA Testing Machine (manufactured by MFG Co, LTD)
(II) Measurement conditions Measurement potential, voltage 50 kV, 50-70 mA
2θ angle a
Crystal plate LiF
Measurement time 60 seconds (III) Method for calculating release rate from toner First, the element strengths of the pre-release toner, the post-release toner, and the external additive-removed toner are obtained by the above-described method. Thereafter, the liberation rate is calculated based on the following formula.
[Formula] Titanium oxide fine particle release rate = 100− (strength of Ti element in toner after release−strength of Ti element in external additive removed toner) / (strength of Ti element in toner before free release−strength of external additive removed toner) Ti element strength) x 100

<Measurement of BET specific surface area of toner, toner particles and external additive>
The measurement of the specific surface area by nitrogen adsorption measured by the BET method was performed according to JIS Z8830 (2001). As the 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 can be used.

  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 material>
(Magnetic material 1)
The following materials were mixed in an aqueous ferrous sulfate solution to prepare an aqueous solution containing ferrous hydroxide.
· The amount of _P 2 _{O 5} with respect to iron in 1.00 1.10 to sodium hydroxide solution, elemental iron equivalent becomes 0.12% by mass in terms of phosphorus
-SiO _{2 in an} amount of 0.60% by mass in terms of silicon element with respect to iron element
The pH of the aqueous solution was 8.0, and an oxidation reaction was performed at a temperature of 85 ° C. while blowing air to prepare a slurry liquid having seed crystals.
Subsequently, the ferrous sulfate aqueous solution was added to this slurry liquid so that it might become 0.90 to 1.20 equivalent with respect to the original alkali amount (sodium component of caustic soda). Thereafter, the slurry liquid was maintained at pH 7.6, and an 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, 1.7 parts by mass of n-hexyltrimethoxysilane coupling agent was added to 100 parts by mass of magnetic iron oxide while stirring (the amount of magnetic iron oxide was calculated as a value obtained by subtracting the water content from the water-containing sample). 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 a temperature of 100 ° C. for 15 minutes, and then at 90 ° C. for 30 minutes. Obtained the magnetic body 1 of 0.23 micrometer.

(Magnetic material 2)
In the production example of the magnetic body 1, a slurry liquid was prepared in the same manner except that SiO ₂ was added in an amount of 0.40% by mass in terms of silicon without adding phosphorus element. In the same manner as in the production example, an oxidation reaction was promoted to obtain a slurry liquid containing magnetic iron oxide.
After filtration, washing and drying, the obtained particles were crushed to obtain a magnetic body 2 having a volume average particle size of 0.21 μm.

<Production example of polyester resin>
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 under a nitrogen stream at a temperature of 230 ° C.
・ 75 parts by mass of bisphenol A propylene oxide 2 mol adduct 25 parts by mass of bisphenol A propylene oxide 3 mol adduct 110 parts by mass of terephthalic acid 0.25 part by mass of titanium catalyst (titanium dihydroxybis (triethanolamate))
Next, the reaction was carried out under reduced pressure of 5 to 20 mmHg. When the acid value became 2 mgKOH / g or less, it was cooled to 180 ° C., 8 parts by mass of trimellitic anhydride was added, and the reaction was taken out for 2 hours under atmospheric pressure sealing, and then taken out. After cooling to 0, pulverization gave polyester resin 1. The obtained polyester resin 1 had a main peak molecular weight (Mp) of 9,500 as measured by gel permeation chromatography (GPC).

<Production Example 1 of Toner Particles>
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.) 2.0 parts by mass Magnetic substance 1 90.0 parts by mass / Polyester resin 1 3.0 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., 15.0 parts by mass of Fischer-Tropsch wax (melting point: 74 ° C., number average molecular weight Mn: 500) was added, mixed and dissolved. After dissolution, 7.0 parts by weight 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 12500 rpm for 12 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) under a temperature of 60 ° C. and N ₂ atmosphere. Thereafter, the mixture was reacted at a temperature of 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 toner particles 1. The physical properties of the obtained toner particles 1 are shown in Table 1.

<Toner particle production examples 2 and 3>
In the toner particle production example 1, toner particles 2 and 3 were produced in the same manner except that the rotation speed of the homomixer was decreased from 12500 rpm to 10500 rpm and 9500 rpm. Table 1 shows the physical properties of the toner particles 2 and 3 thus obtained.

<Toner Particle Production Example 4>
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 2 • iron complex of monoazo dye (T-77: Hodogaya Chemical Co., Ltd.) 2.0 parts by mass • 4 parts by mass of Fischer-Tropsch wax (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 mechanically pulverized (pulverized). The finely pulverized product was classified and removed at the same time by a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to obtain toner particles A.
The toner particles A were subjected to a thermal spheronization process. The thermal spheronization treatment was performed using a surfing system (manufactured by Nippon Pneumatic Co., Ltd.). The operating conditions of the thermal spheronizer are: feed amount = 5 kg / hour, hot air temperature C = 260 ° C., hot air flow rate = 6 m ³ / min, cold air temperature E = 5 ° C., cold air flow rate = 4 m ³ / min, cold air absolute moisture content = 3 g / m ³ , blower airflow = 20 m ³ / min, injection air flow rate = 1 m ³ / min, diffusion air = 0.3 m ³ / min.
By the surface treatment under the above conditions, toner particles 4 having a weight average particle diameter (d4) of 8.2 μm were obtained. The physical properties of the obtained toner particles 4 are shown in Table 1.

<Toner Particle Production Example 5>
In Toner Particle Production Example 4, the obtained toner particles A were subjected to surface modification and fine powder removal using a surface modification device faculty (manufactured by Hosokawa Micron Corporation) to obtain toner particles 5. The conditions for surface modification and fine powder removal using the surface modification equipment faculty were as follows.
・ Rotating peripheral speed of dispersed rotor 200m / sec ・ Input amount of finely pulverized product 6kg per cycle
・ Surface modification time (cycle time: time from the end of raw material supply until the discharge valve opens)
90 seconds The temperature when discharging the toner particles was 45 ° C. The physical properties of the obtained toner particles 5 are shown in Table 1. The true density of toner particles 1 to 5 was measured and found to be 1.6 g / cm ³ .

<Production Example 1 of Silica Fine Particle>
Untreated dry silica (average primary particle size = 9 nm) was charged into an autoclave equipped with a stirrer, and heated to 200 ° C. in a fluidized state by stirring.
The inside of the reactor was replaced with nitrogen gas, the reactor was sealed, and 25 parts by mass of hexamethyldisilazane was sprayed inside with respect to 100 parts by mass of dry silica, and the silane compound treatment was performed in a fluidized state of silica. . This reaction was continued for 60 minutes, and then the reaction was terminated. After completion of the reaction, the autoclave was depressurized and washed with a nitrogen gas stream to remove excess hexamethyldisilazane and by-products from the hydrophobic silica.
Further, 10 parts by mass of dimethyl silicone oil (viscosity = 100 mm ² / sec) was sprayed on 100 parts by mass of dry silica while stirring the reaction vessel, and stirring was continued for 30 minutes. Thereafter, the temperature was raised to 300 ° C. with stirring, and the mixture was further stirred for 2 hours and then taken out and pulverized to obtain silica fine particles 1. The physical properties of the silica fine particles 1 are shown in Table 2.

<Production Examples 2 to 7 of silica fine particles>
Silica fine particles 2 to 7 were obtained in the same manner as in Production Example 1 of silica fine particles except that the particle size of the untreated silica used was changed and the crushing strength was appropriately adjusted. Table 2 shows the physical properties of the silica fine particles 2 to 7. In addition, as a result of measuring a true density about silica fine particles 1-7, all were 2.2 g / cm < ³ >.

<Titanium oxide fine particle production example 1>
Ilmenite ore containing 50% by mass of TiO ₂ equivalent was used as a starting material. This raw material was dried at a temperature of 150 ° C. for 2 hours, and sulfuric acid was added and dissolved to obtain an aqueous solution of TiOSO ₂ . Sodium carbonate was added to this aqueous solution to adjust the pH to 9.0, neutralized with alkali, and filtered to obtain a white precipitate. Pure water was added to the white precipitate and the mixture was heated for 2.5 hours while being kept at a temperature of about 90 ° C., subjected to hydrolysis treatment, and repeatedly subjected to filtration and water washing to obtain anatase-type titanium oxide.
The obtained anatase-type titanium oxide was sintered by high-temperature heating at 1100 ° C. to obtain a rutile-type titanium oxide. The rutile titanium oxide was crushed with a jet mill to obtain titanium oxide fine particles. The titanium oxide fine particles are dispersed in ethanol, and 10 parts by mass of solid component of i-butyltrimethoxysilane as a hydrophobizing agent with respect to 100 parts by mass of the titanium oxide fine particles is sufficiently prevented. Hydrophobic treatment was carried out by mixing dropwise with stirring and reacting.
Furthermore, the pH of the slurry was adjusted to 6.5 with sufficient stirring. This was filtered and dried, then heat-treated at a temperature of 170 ° C. for 2 hours, and then repeatedly crushed by a jet mill until the aggregate of titanium oxide disappeared to obtain titanium oxide fine particles 1.

<Production Examples 2 to 16 of titanium oxide fine particles>
In the production example 1 of titanium oxide fine particles, the same procedure was performed except that the hydrolysis temperature and time were changed, the pulverization treatment conditions in the jet mill, and the addition amount of i-butyltrimethoxysilane used in the hydrophobization treatment were changed. Preparation was performed to obtain rutile-type titanium oxide fine particles 2 to 16. Table 3 shows the physical properties of the titanium oxide fine particles 2 to 16.

<Production Example 17 of Titanium Oxide Fine Particles>
In the production example of the titanium oxide fine particles 1, the temperature and time for hydrolysis were changed, and the sintering temperature by high-temperature heating at 1100 ° C. was changed to 700 ° C. to obtain anatase-type titanium oxide. Anatase-type titanium oxide fine particles 17 were obtained in the same manner except that the crushing treatment conditions in the jet mill and the addition amount of i-butyltrimethoxysilane used in the hydrophobization treatment were changed. Table 3 shows the physical properties of the titanium oxide fine particles 17.

<Toner Production Example 1>
The toner particles 1 obtained in Production Example 1 of toner particles were subjected to an external addition mixing process using the apparatus shown in FIG.
In the present embodiment, the apparatus shown in FIG. 3 is used, 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 of FIG. Then, the overlapping width d of the stirring member 3a and the stirring member 3b in FIG. 4 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 casing 1 is 3.0 mm. did.
In the apparatus configuration described above, 100 parts by mass of toner particles 1, 0.40 parts by mass of silica fine particles 1 hydrophobized with silicone oil and a silane coupling agent, and 0.30 parts by mass of titanium oxide fine particles 1 Was put into the apparatus shown in FIG.

(Pre-mixed)
After the toner particles, silica fine particles, and titanium oxide fine particles were added, pre-mixing was performed in order to uniformly mix the toner particles, silica fine particles, and titanium oxide 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.
(First stage external mixing)
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 3 minutes.
(Second stage external mixing)
Thereafter, 0.10 parts by mass of silica fine particles 1 are added (total 0.50 parts by mass with respect to the toner particles), and the power of the drive unit 8 is kept constant at 0.60 W / g (the rotational speed of the drive unit 8 is 1400 rpm). Thus, the outermost peripheral speed of the stirring member 3 was adjusted, and the treatment was further performed for 2 minutes.
That is, the ratio of the content of silica fine particles 1 (0.50 parts by mass) to the content of titanium oxide fine particles 1 (0.30 parts by mass) was 5/3 = 1.7.

  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, whereby toner 1 was obtained. The 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 toner particles was measured and found to be 9 nm. Further, when the major axis diameter and minor axis diameter of the titanium oxide fine particles on the surface of the toner particles were measured, they were 83 nm and 20 nm, respectively. Table 4 shows the external addition conditions and physical properties of Toner 1.

<Production Examples of Toners 2 to 39 and Comparative Toners 1 to 16>
In the production example of the toner 1 for Example, the same manner as in Table 2, Table 3 or Table 4 except that the type and number of added external additives, toner particles, external addition device, external addition conditions, etc. were changed. Toners 2-39 and Comparative Toners 1-16 were produced. Tables 4 and 5 show external addition conditions of the obtained toners 2 to 39 and comparative toners 1 to 16, and Table 6 shows physical properties thereof.
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.

外添装置は全て図３に示す装置。 プレ混合条件：処理時間は全て１分間
一段目の外添条件：動力は全て０．６０（Ｗ／ｇ）、回転数は全て１４００（ｒｐｍ）
二段目の外添条件：動力は全て０．６０（Ｗ／ｇ）、回転数は全て１４００（ｒｐｍ）

All external devices are shown in FIG. Pre-mixing conditions: All treatment times are 1 minute External addition conditions: All power is 0.60 (W / g), All rotations are 1400 (rpm)
Second stage external conditions: All power is 0.60 (W / g), all rotations are 1400 (rpm)

表中、拡散指数下限（−）は、式２における、（−０．００４２×Ｘ１＋０．６２）の値を指す。

In the table, the diffusion index lower limit (−) refers to the value of (−0.0042 × X1 + 0.62) in Equation 2.

<Example 1>
(Image forming device)
An LBP-3100 (manufactured by Canon Inc.) equipped with a sleeve having a diameter of 10 mm was used as the image forming apparatus, and the image forming apparatus was modified so that the transfer bias could be changed by connecting an external power source. When the transfer bias is lowered, transfer omission is likely to occur in a medium having a low volume resistance such as moisture absorbent paper made in a high temperature and high humidity environment as described above. In addition, the volume of the toner filling portion was modified to 1.5 times.
By increasing the volume by 1.5 times, it is possible to promote toner deterioration and to strictly evaluate image density and fog. Using this modified machine, one solid black image is obtained using toner 1 at a normal transfer bias (0.5 kV) in a high temperature and high humidity environment (temperature 32.5 ° C./relative humidity 80% RH). Output. Thereafter, a 2000-line image printing test was performed in a 1-sheet intermittent mode with a horizontal line having a printing rate of 2%. After 2000 images were printed, a single solid black image was printed. Thereafter, the transfer bias was set to 0.3 kV, and one solid black image was output using moisture-absorbing paper described later.
Further, the evaluation of fogging was performed by using the above-described modified machine and outputting one solid white image in a normal temperature and humidity environment (temperature 23 ° C./relative humidity 50% RH).

As a result, it was possible to obtain an image having a high image density before and after the endurance use test, no transfer omission, and little fogging on the non-image area. Table 7 shows the evaluation results.
The evaluation methods for each evaluation performed in the examples and comparative examples of the present invention and the judgment criteria thereof will be described below.

<Image density>
The image density formed a solid black image portion, and the density of the solid black image was measured with a Macbeth reflection densitometer (manufactured by Macbeth). As the paper, OCE RED LABEL (A4, 80 g / cm ² ) was used. The paper was used in a state opened from a paper bag immediately before the image was printed.
The criteria for determining the reflection density of a solid black image at the initial stage of durable use (first sheet) are as follows.
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: Bad (less than 1.35)

The criteria for determining the image density in the second half of the endurance use are as follows.
The smaller the difference between the reflection density of the solid black image at the initial stage of durable use and the reflection density of the solid black image after the durable use of 2000 sheets, the better.
A: Very good (difference is less than 0.10)
B: Good (difference is 0.10 or more and less than 0.15)
C: Normal (difference is 0.15 or more and less than 0.20)
D: Bad (difference is 0.20 or more)

<Cover>
A solid white image was output, and the reflectance was measured using a REFECTMETER MODEL TC-6DS made by Tokyo Denshoku. On the other hand, the reflectance of the transfer paper (standard paper) before solid white image formation was measured in the same manner. A green filter was used as the filter. From the reflectance before and after outputting the solid white image, the fog was calculated using the following formula.
Fog (reflectance) (%) = reflectance of standard paper (%) − reflectance of solid white image sample (%)
The criteria for determining fogging are as follows.
A: Very good (less than 1.0%)
B: Good (1.0% or more and less than 1.5%)
C: Normal (1.5% or more and less than 2.5%)
D: Poor (2.5% or more)

<Transfer missing>
Paper OCE RED LABEL (A4, 80 g / cm ² ) was left standing for 48 hours in a high temperature and high humidity environment (temperature 32.5 ° C./relative humidity 80% RH) in a state opened from a paper bag. The transfer bias was changed to 0.3 kV, and a solid black image was output after the endurance use of the above-mentioned 2000 sheets, and the visual evaluation was performed. As described above, the transferability can be strictly evaluated by evaluating the paper that has been allowed to stand in a high-temperature and high-humidity environment.
A: Very good (transfer missing has not occurred)
B: An image having some density unevenness but no problem in practical use C: Although an uneven density is observed, an image having no problem practically D: Clear density unevenness is observed. Image unfavorable for practical use E: A white portion is seen on a solid black image. Practical unfavorable image

<Examples 2 to 39>
An image formation test was performed in the same manner as in Example 1 except that the toners 2 to 39 were used. As a result, an image with a level that is practically satisfactory before and after the endurance test was obtained for each toner. Table 7 shows the evaluation results.
<Comparative Examples 1-16>
An image printing test was performed in the same manner as in Example 1 except that the comparative toners 1 to 16 were used. Table 7 shows the evaluation results.

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: Development blade, 114: Transfer member (transfer roller), 116: Waste toner container, 117: Charging member (charging roller), 121: laser generating device (latent image forming means, exposure device), 123: laser, 124: pickup roller, 125: conveying belt, 126: fixing device, 140: developing device, 141: stirring Member

Claims (5)

Toner particles containing a binder resin and a colorant;
Titanium oxide fine particles and silica fine particles as external additives,
A toner having
The titanium oxide fine particles are:
The major axis diameter is 30 nm or more and 500 nm or less,
The minor axis diameter is 10 nm or more and 80 nm or less,
Rutile-type titanium oxide fine particles having a major axis diameter / minor axis diameter ratio of 2.0 or more and 8.0 or less,
The titanium oxide fine particle content is 0.1 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the toner particles,
The ratio of the content of the silica fine particles to the content of the titanium oxide fine particles in the toner is 0.4 or more and 30.0 or less,
The coverage X1 with the silica fine particles on the surface of the toner particles determined by an X-ray photoelectron spectrometer (ESCA) is 40.0 area% or more and 75.0 area% or less,
When the theoretical coverage by the silica fine particles is X2, the diffusion index represented by the following formula 1 satisfies the following formula 2,
The toner according to claim 1, wherein an embedding rate of the external additive in the toner particles is 25% or more and 60% or less.
(Formula 1) Diffusion index = X1 / X2
(Expression 2) Diffusion index ≧ −0.0042 × X1 + 0.62   The toner according to claim 1, wherein the toner particles have an average circularity of 0.960 or more.   The toner according to claim 1, wherein a liberation rate of the titanium oxide fine particles is 50% or less.   The toner according to claim 1, wherein an apparent density of the silica fine particles is 15 g / L or more and 50 g / L or less.   The toner particles are formed by forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in an aqueous medium, and polymerizing the polymerizable monomer contained in the particles. The toner according to claim 1, wherein the toner particles are obtained.

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