JP2021036303A - Magnetic carrier, two-component developer, replenishing developer and image formation method - Google Patents

Abstract

To provide a magnetic carrier and the like which can achieve both of the density stability of an image in environment change and the developability in the long-term use.SOLUTION: A magnetic carrier comprises a magnetic carrier core and a resin coating layer formed on the surface of the magnetic carrier core. The resin coating layer comprises: a first resin coating layer which contains a polymer having a prescribed structure; and a second resin coating layer which is formed on the surface of the first resin coating layer and contains vinyl resin. In the XPS measurement to the magnetic carrier, a ratio N1 of the nitrogen atoms derived from quaternary ammonium salt on the magnetic carrier surface is equal to or less than 0.5 atom%. When the layer thickness of the resin coating layer is d (μm), a ratio N2 of the nitrogen atoms derived from the quaternary ammonium salt at a position of a distance of 0.95×d with respect to the depth direction to the magnetic carrier core from the surface of the magnetic carrier is 1.0-10.0 atom%.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetic carrier used in an image forming method for visualizing an electrostatic charge image using an electrophotographic method, a two-component developer using the magnetic carrier, a supplementary developer, and an image. Regarding the forming method.

Conventionally, in the electrophotographic image forming method, an electrostatic latent image is formed on an electrostatic latent image carrier by various means, and toner is adhered to the electrostatic latent image to form the electrostatic latent image. The method of developing is common. In this development, a two-component developing method is widely used in which carrier particles called magnetic carriers are mixed with toner, triboelectrically charged, an appropriate amount of positive or negative electric charge is given to the toner, and the electric charge is developed as a driving force. It has been adopted.
In the two-component developing method, functions such as stirring, transporting, and charging the developer can be added to the magnetic carrier, so that the division of functions with the toner is clear, and therefore the controllability of the developer performance is good. There are advantages.

On the other hand, in recent years, due to technological evolution in the field of electrophotographic photography, it has become more and more strict to have high definition and stable image quality as well as high speed and long life of the device. In order to meet such demands, higher performance of magnetic carriers is required.
For example, as the speed of the device increases and the image density increases, the amount of toner replenished in the developing device increases, and the external additives and toner present on the surface of the toner particles adhere to the resin coating layer on the surface of the magnetic carrier. Is promoted. Therefore, it is required not only to improve the toughness and wear resistance of the resin coating layer, but also to reduce the adhesiveness to toner-derived components.

In order to solve such a problem, it has been proposed to reduce the concentration fluctuation even in long-term use especially under high temperature and high humidity, and to stabilize the charge amount even when left for a long period of time (for example, Patent Documents 1 to 9). ). The magnetic carriers described in these documents are characterized by having an amino group or a quaternary ammonium salt structure in the coating resin.

Japanese Unexamined Patent Publication No. 2013-061467 Japanese Unexamined Patent Publication No. 2017-142496 Japanese Unexamined Patent Publication No. 2017-044792 Japanese Unexamined Patent Publication No. 2011-158831 Japanese Unexamined Patent Publication No. 2018-017862 Japanese Unexamined Patent Publication No. 2009-139468 Japanese Unexamined Patent Publication No. 2009-300792 Japanese Unexamined Patent Publication No. 2007-12777 Japanese Unexamined Patent Publication No. 2012-078814

The magnetic carrier described in the above patent document has improved the problem of stabilizing the charge amount.
However, in the market, especially in the field of on-demand printers, the demand for stable image quality during long-term use is becoming more stringent. Among them, both charge stability and developability during long-term use and environmental changes are not sufficient.
The present invention provides a magnetic carrier that solves the above problems. Specifically, a magnetic carrier capable of achieving both image density stability under environmental changes and developability during long-term use, a two-component developer using the magnetic carrier, a supplementary developer, and an image. It provides a forming method.

（式（１）中、Ｒ^１〜^３は、それぞれ独立して水素原子または炭素数１〜８のアルキル基を表し、Ｒ^４は炭素数１〜２０のアルキレン基を表し、Ｒ^５は、水素原子またはメチル基を表し、Ｘ⁻は、アニオンを表す。） The present inventors have found that a magnetic carrier as shown below can achieve both image density stability under environmental changes and developability during long-term use.
That is, the present invention
A magnetic carrier having a magnetic carrier core and a resin coating layer formed on the surface of the magnetic carrier core.
The resin coating layer is
A first resin coating layer containing a polymer having a structure represented by the following formula (1),
It has a second resin coating layer containing a vinyl resin formed on the surface of the first resin coating layer.
In the measurement by X-ray photoelectron spectroscopy for the magnetic carrier,
The ratio N1 of the number of nitrogen atoms derived from the quaternary ammonium salt on the surface of the magnetic carrier is 0.5 atomic% or less.
When the layer thickness of the resin coating layer is d (μm), it is derived from a quaternary ammonium salt at a position of 0.95 × d (μm) from the surface of the magnetic carrier to the magnetic carrier core in the depth direction. It relates to a magnetic carrier in which the ratio N2 of the number of nitrogen atoms is 1.0 atomic% or more and 10.0 atomic% or less.

(In the formula (1), R ¹ to ³ independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁴ represents an alkylene group having 1 to 20 carbon atoms, and R ⁵ represents hydrogen. Represents an atom or a methyl group, where X ⁻ represents an anion.)

In addition, the present invention
A two-component developer containing a toner having toner particles containing a binder resin and a magnetic carrier.
The present invention relates to a two-component developer in which the magnetic carrier is the magnetic carrier of the present invention.

Furthermore, the present invention
Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing process in which the electrostatic latent image is developed using a two-component developer in a developing device to form a toner image.
It has a transfer step of transferring the toner image to the transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
A replenishing developer for use in an image forming method in which a replenishing developer is replenished to the developing device in response to a decrease in the toner concentration of the two-component developing agent in the developing device.
The replenishing developer contains a magnetic carrier and a toner having toner particles containing a binder resin.
The replenishing developer contains 2 parts by mass or more and 50 parts by mass or less of the toner with respect to 1 part by mass of the magnetic carrier.
The magnetic carrier relates to a replenishing developer which is the magnetic carrier of the present invention.

Furthermore, the present invention
Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing step of developing the electrostatic latent image with a two-component developer to form a toner image.
An image forming method comprising a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
The two-component developer relates to an image forming method, which is the two-component developer of the present invention.

Furthermore, the present invention
Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing process in which the electrostatic latent image is developed using a two-component developer in a developing device to form a toner image.
It has a transfer step of transferring the toner image to the transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
An image forming method in which a replenishing developer is replenished to the developing device according to a decrease in the toner concentration of the two-component developing agent in the developing device.
The replenishing developer relates to an image forming method which is the replenishing developer of the present invention.

According to the present invention, a magnetic carrier capable of achieving both image density stability under environmental changes and developability during long-term use, a two-component developer using the magnetic carrier, a supplementary developer, and a developer. An image forming method can be provided.

Schematic diagram of the cross section of the magnetic carrier of the present invention and the measurement position of X-ray photoelectron spectroscopy. Schematic diagram of the image forming apparatus Schematic diagram of the image forming apparatus

In the present invention, the description of "XX or more and YY or less" or "XX to YY" indicating a numerical range means a numerical range including a lower limit and an upper limit which are end points, unless otherwise specified.
"Monomer unit" refers to the reacted form of a monomeric substance in a polymer. For example, one carbon-carbon bond section in the main chain in which the vinyl-based monomer in the polymer is polymerized is defined as one unit.
In the present invention, "(meth) acrylic" means "acrylic" and / or "methacryl".

The magnetic carrier of the present invention
A magnetic carrier having a magnetic carrier core and a resin coating layer formed on the surface of the magnetic carrier core.
The resin coating layer is
A first resin coating layer containing a polymer having a structure represented by the following formula (1),
It has a second resin coating layer containing a vinyl resin formed on the surface of the first resin coating layer.
In the measurement by X-ray photoelectron spectroscopy for the magnetic carrier,
The ratio N1 of the number of nitrogen atoms derived from the quaternary ammonium salt on the surface of the magnetic carrier is 0.5 atomic% or less.
When the layer thickness of the resin coating layer is d (μm), it is derived from a quaternary ammonium salt at a position of 0.95 × d (μm) from the surface of the magnetic carrier to the magnetic carrier core in the depth direction. The ratio N2 of the number of nitrogen atoms is 1.0 atomic% or more and 10.0 atomic% or less.

Usually, it is known that a structure having an amino group or a quaternary ammonium salt structure is contained in the coating resin of the magnetic carrier to improve the chargeability of the negatively charged toner.
However, when these structures are present on the surface of the magnetic carrier, the chargeability in the room temperature and low humidity environment tends to be higher than the chargeability in the high temperature and high humidity environment. As a result, there is a large difference in the amount of charge due to changes in the environment, especially humidity, and changes in image density and color are likely to occur.

Therefore, by incorporating a primer compound having an amino group into the magnetic carrier core and coating the surface with an acrylic resin, excessive improvement in chargeability in a low humidity environment is suppressed, and the difference in the amount of charge due to changes in humidity is reduced. Was considered. However, it has been found that the content of the primer compound having an amino group is limited, and that excessive content of the compound causes various harmful effects. One of them is to increase the resistance of magnetic carriers.
The original role of the magnetic carrier is to stably supply toner to the photoconductor in the developing device and to cause the toner to fly by an electric field. For that purpose, it is essential to adjust the resistance of the magnetic carrier. However, when a primer compound having an amino group is contained in the magnetic carrier core and a coating layer of an acrylic resin is provided, the resistance of the magnetic carrier increases. It was found that the developability was reduced. Therefore, the present inventors have conducted diligent studies in order to improve the developability while reducing the difference in the amount of charge depending on the environment.

（式（１）中、Ｒ^１〜^３は、それぞれ独立して水素原子または炭素数１〜８（好ましくは炭素数１〜４）のアルキル基を表し、Ｒ^４は炭素数１〜２０（好ましくは炭素数１〜１０）のアルキレン基を表し、Ｒ^５は、水素原子またはメチル基（好ましくはメチル基）を表し、Ｘ⁻は、アニオン（好ましくはハロゲンイオン、より好ましくはＣｌ⁻）を表す。）
上記式（１）で示される構造の含有量は、第一樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、２．０質量％〜２０．０質量％であることが好ましく、３．０質量％〜１５．０質量％であることがより好ましい。 The magnetic carrier of the present invention has a magnetic carrier core and a resin coating layer.
In addition, the resin coating layer is
It has a first resin coating layer formed on the surface of the magnetic carrier core and containing a polymer having a structure represented by the following formula (1).

(In the formula (1), R ¹ to ³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms (preferably 1 to 4 carbon atoms), and R ⁴ has 1 to 20 carbon atoms (preferably). Represents an alkylene group having 1 to 10) carbon atoms, R ⁵ represents a hydrogen atom or a methyl group (preferably a methyl group), and X ⁻ represents an anion (preferably a halogen ion, more preferably Cl ⁻ ). .)
The content of the structure represented by the above formula (1) is preferably 2.0% by mass to 20.0% by mass based on all the monomer units of the resin contained in the first resin coating layer. More preferably, it is 0% by mass to 15.0% by mass.

The structure represented by the above formula (1) is a structure derived from (meth) acrylate having a quaternary ammonium salt structure. It is known that amino groups and quaternary ammonium salts impart strong positive chargeability to magnetic carriers by donating electrons in the nitrogen element portion. In particular, the effect is further enhanced when the magnetic carrier contains a quaternary ammonium salt.
In the present invention, by making this quaternary ammonium salt structure a part of the polymer contained in the primary resin coating layer, the ratio of the quaternary ammonium structure and the ratio of the primary resin coating layer are adjusted according to the target charge level. The thickness can be adjusted freely.

However, since a polymer having a quaternary ammonium salt structure has a very high charge-imparting ability, when the quaternary ammonium salt structure is exposed on the surface of a magnetic carrier, the chargeability in a low-humidity environment becomes high, and the amount of charge due to the environment increases. The effect of reducing the difference is lost. Therefore, the present inventors have designed to suppress excessive improvement in chargeability in a low humidity environment by providing a second resin coating layer containing a vinyl resin on the surface of the first resin coating layer.
That is, the resin coating layer on the magnetic carrier of the present invention is
It has a second resin coating layer containing a vinyl resin formed on the surface of the first resin coating layer.

Further, in the magnetic carrier of the present invention, the ratio N1 of the number of nitrogen atoms derived from the quaternary ammonium salt on the surface of the magnetic carrier is 0.5 atomic% in the measurement by X-ray photoelectron spectroscopy (hereinafter, also referred to as XPS) with respect to the magnetic carrier. It is as follows. Further, when the layer thickness of the resin coating layer is d (μm), it is derived from a quaternary ammonium salt at a position of 0.95 × d (μm) from the surface of the magnetic carrier to the magnetic carrier core in the depth direction. The ratio N2 of nitrogen atoms is 1.0 atomic% or more and 10.0 atomic% or less. It has been found that when N1 and N2 satisfy the above range, the quaternary ammonium salt structure exists in the resin coating layer without being excessively exposed on the surface of the magnetic carrier, and the effect of the present invention is exhibited.

N1 is preferably 0.3 atomic% or less, more preferably 0.2 atomic% or less, and further preferably 0.1 atomic% or less. The lower limit of N1 is not particularly limited, but is preferably 0.0 atomic% or more. The numerical ranges can be combined arbitrarily.
By suppressing N1 to 0.5 atomic% or less, it is possible to reduce the difference in the amount of charge depending on the environment, and the image density is stable even if the environment changes. In the present invention, as means for suppressing N1 to 0.5 atomic% or less, for example, the first resin coating layer contains a curable vinyl structure, or the first resin coating layer used at the time of manufacturing a magnetic carrier is formed. For example, changing the amount of resin to be used. By forming a part or all of the first resin coating layer into a curable vinyl structure and allowing the curing reaction to occur, the transfer of the quaternary ammonium structure to the second resin coating layer can be further suppressed.

（式（３）中、Ｒ^７は、ＨまたはＣＨ_３を示し、Ｚは、Ｈまたは炭素数１〜２０（好ましくは炭素数１〜１０）の炭化水素基である。）
上記式（３）で示される構造の含有量は、第一樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、１０．０質量％〜９０．０質量％であることが好ましく、２０．０質量％〜８５．０質量％であることがより好ましい。 It is preferable that the polymer having the structure represented by the above formula (1) further has the structure represented by the following formula (3).

(In the formula (3), R ⁷ represents H or CH ₃ , and Z is H or a hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms).
The content of the structure represented by the above formula (3) is preferably 10.0% by mass to 90.0% by mass, based on all the monomer units of the resin contained in the first resin coating layer. More preferably, it is 0% by mass to 85.0% by mass.

（式（４）中、Ｒ^８、Ｒ^９は、それぞれ独立して炭素数１〜２０（好ましくは炭素数１〜９）の炭化水素基である。）
上記式（４）で示される構造の含有量は、第一樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、１．０質量％〜３０．０質量％であることが好ましく、２．０質量％〜１５．０質量％であることがより好ましい。

（式（５）中、Ｒ^１０、Ｒ^１１は、それぞれ独立して炭素数１〜２０（好ましくは炭素数１〜９）の炭化水素基である。）
上記式（５）で示される構造の含有量は、第一樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、１．０質量％〜３０．０質量％であることが好ましく、２．０質量％〜１５．０質量％であることがより好ましい。

（式（６）中、Ｒ^１２、Ｒ^１３は、それぞれ独立して炭素数１〜２０（好ましくは炭素数１〜９）の炭化水素基である。）
上記式（６）で示される構造の含有量は、第一樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、１．０質量％〜３０．０質量％であることが好ましく、２．０質量％〜１５．０質量％であることがより好ましい。 It is also preferable that the polymer having the structure represented by the above formula (1) has at least one structure selected from the group consisting of the structures represented by the following formulas (4) to (6).

(In the formula (4), R ⁸ and R ⁹ are each independently a hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 9 carbon atoms).)
The content of the structure represented by the above formula (4) is preferably 1.0% by mass to 30.0% by mass based on all the monomer units of the resin contained in the first resin coating layer. More preferably, it is 0% by mass to 15.0% by mass.

(In the formula (5), R ¹⁰ and R ¹¹ are each independently a hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 9 carbon atoms).)
The content of the structure represented by the above formula (5) is preferably 1.0% by mass to 30.0% by mass based on all the monomer units of the resin contained in the first resin coating layer. More preferably, it is 0% by mass to 15.0% by mass.

(In the formula (6), R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 9 carbon atoms).)
The content of the structure represented by the above formula (6) is preferably 1.0% by mass to 30.0% by mass based on all the monomer units of the resin contained in the first resin coating layer. More preferably, it is 0% by mass to 15.0% by mass.

（式（７）中、Ｒ^１４は炭素数１〜２０（好ましくは炭素数１〜９）の炭化水素基である。）
上記式（７）で示される構造の含有量は、第一樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、１．０質量％〜３０．０質量％であることが好ましく、２．０質量％〜１５．０質量％であることがより好ましい。 It is also preferable that the polymer having the structure represented by the above formula (1) further has the structure represented by the following formula (7).

(In the formula (7), R ¹⁴ is a hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 9 carbon atoms).)
The content of the structure represented by the above formula (7) is preferably 1.0% by mass to 30.0% by mass based on all the monomer units of the resin contained in the first resin coating layer. More preferably, it is 0% by mass to 15.0% by mass.

The structures represented by the above formulas (4) to (7) can be formed by causing a curing reaction of a monomer having an epoxy group and a carboxy group with heat, a catalyst or the like.

N2 is 1.0 atomic% or more and 10.0 atomic% or less, preferably 3.0 atomic% or more and 9.0 atomic% or less, and more preferably 4.0 atomic% or more and 8.0 atomic% or less. is there. By setting N2 to 1.0 atomic% or more and 10.0 atomic% or less, it is possible to improve the chargeability in a high humidity environment and suppress the occurrence of white spots due to a decrease in developability. In order to keep N2 in the above range, it can be easily controlled by adjusting the ratio of the quaternary ammonium salt structure of the first resin coating layer, adjusting the layer thickness of the first resin coating layer, and the like.

Since the ionic conductivity is enhanced by containing the polymer having the structure represented by the above formula (1) in the first resin coating layer, even if the amount of the coating resin is increased and the layer thickness of the resin coating layer is increased. , There is an advantage that resistance is hard to improve. Therefore, by using the magnetic carrier of the present invention, it is possible to reduce the difference in chargeability depending on the environment and to achieve both developability.

（式（２）中、Ｒ^６は、ＨまたはＣＨ_３（好ましくはＣＨ_３）を示し、Ｙは炭素数４〜１２（好ましくは５〜９）の環状構造を有する炭化水素基である。）
上記式（２）で示される構造の含有量は、第二樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、３０．０質量％〜９０．０質量％であることが好ましく、４０．０質量％〜８０．０質量％であることがより好ましい。 The vinyl-based resin contained in the second resin coating layer preferably contains a polymer of a monomer containing a (meth) acrylic acid ester having an alicyclic hydrocarbon group. Such a resin has a function of smoothing the coating film surface of the resin coated on the surface of the magnetic carrier core, suppressing the adhesion of toner-derived components, and suppressing the decrease in chargeability. In addition, the stirring speed of the developer is stabilized, and the stability of concentration and in-plane uniformity are further stabilized.
Examples of the monomer containing a (meth) acrylic acid ester having an alicyclic hydrocarbon group include cyclobutyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, cycloheptyl acrylate, dicyclopentenyl acrylate, and dicyclo acrylate. Examples thereof include pentanyl, cyclobutyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, dicyclopentenyl methacrylate and dicyclopentanyl methacrylate. These monomers may be used alone or in combination of two or more.
That is, the vinyl resin contained in the second resin coating layer preferably has a structure represented by the following formula (2).

(In the formula (2), R ⁶ represents H or CH ₃ (preferably CH ₃ ), and Y is a hydrocarbon group having a cyclic structure having 4 to 12 carbon atoms (preferably 5 to 9).)
The content of the structure represented by the above formula (2) is preferably 30.0% by mass to 90.0% by mass, based on all the monomer units of the resin contained in the second resin coating layer. More preferably, it is 0% by mass to 80.0% by mass.

式（８）中、Ｒ^１５は、ＨまたはＣＨ_３（好ましくはＣＨ_３）を示す。Ｍ’は、重合体を主鎖とする二価の官能基であり、該重合体は、アクリル酸メチル、メタクリル酸メチル、アクリル酸ブチル（ｎ−ブチル、ｓｅｃ−ブチル、ｉｓｏ−ブチル及びｔｅｒｔ−ブチルからなる群から選択される少なくとも一）、メタクリル酸ブチル、アクリル酸２−エチルヘキシル、メタクリル酸２−エチルヘキシル、スチレン、アクリロニトリル、及びメタクリロニトリルからなる群より選ばれる少なくとも一のモノマーの重合体である。Ｍ’は、メタクリル酸メチルの重合体である二価の官能基であることが好ましい。
マクロモノマー部の重量平均分子量（Ｍｗ）は、好ましくは２０００以上１００００以下であり、より好ましくは３０００以上８０００以下である。
マクロモノマー部の含有量は、第二樹脂被覆層に含まれる樹脂の全モノマーユニットを基準として、５．０質量％以上５０．０質量％以下であることが好ましく、５．０質量％以上４０．０質量％以下であることがより好ましい。 Further, the vinyl resin contained in the second resin coating layer more preferably has a structure represented by the above formula (2) and a structure represented by the following formula (8). A specific example represented by the formula (8) is a macromonomer. By using such a macromonomer, the transport stability of the developer is more effective, and the stability of the image density is also improved.

In formula (8), R ¹⁵ represents H or CH ₃ (preferably CH ₃ ). M'is a divalent functional group having a polymer as a main chain, and the polymers are methyl acrylate, methyl methacrylate, butyl acrylate (n-butyl, sec-butyl, iso-butyl and tert-). A polymer of at least one monomer selected from the group consisting of at least one) selected from the group consisting of butyl, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, acrylonitrile, and methacrylonitrile. is there. M'is preferably a divalent functional group which is a polymer of methyl methacrylate.
The weight average molecular weight (Mw) of the macromonomer portion is preferably 2000 or more and 10000 or less, and more preferably 3000 or more and 8000 or less.
The content of the macromonomer portion is preferably 5.0% by mass or more and 50.0% by mass or less, preferably 5.0% by mass or more and 40% by mass or more, based on all the monomer units of the resin contained in the second resin coating layer. More preferably, it is 0.0% by mass or less.

The layer thickness d of the resin coating layer is preferably 0.5 μm or more and 6.0 μm or less, and more preferably 0.8 μm to 5.0 μm. When the layer thickness d is within the above range, the difference in the amount of charge depending on the environment is further reduced and the developability is improved, which is preferable. The layer thickness d can be controlled by the resin concentration and the amount of the resin liquid for the resin coating layer used during the production of the magnetic carrier. For example, the layer thickness d can be increased by increasing the resin concentration of the resin liquid for the first resin coating layer and the resin liquid for the second resin coating layer, or increasing the amount used.
The proportion of the first resin coating layer in the resin coating layer is preferably 50% or less, more preferably 10% or more and 45% or less. The ratio of the second resin coating layer to the resin coating layer is preferably 50% or more, more preferably 55% or more and 90% or less.

Next, the magnetic carrier core will be described.
As the magnetic carrier core, a known magnetic carrier core can be used. For example, in addition to the conventionally used magnetic carrier core, it is possible to use magnetic material-dispersed resin particles in which the magnetic material component is dispersed in the resin component, or porous magnetic core particles containing resin in the voids. it can.
The magnetic material component contained in the magnetic material dispersed resin particles is selected from, for example, magnetite particles, magnetite particles, or silicon oxide, silicon hydroxide, aluminum oxide, and aluminum hydroxide. Magnetic iron oxide particles containing at least one; magnetite plumpite-type ferrite particles containing at least one selected from barium and strontium; spinel-type ferrite particles containing at least one selected from manganese, nickel, zinc, lithium and magnesium, etc. Various magnetic iron compound particles can be used.
Among these, magnetic iron oxide particles can be preferably used.

In addition to the above-mentioned magnetic material components, the magnetic material dispersion type resin particles include non-magnetic iron oxide particles such as hematite particles, non-magnetic ferric hydroxide particles such as gateite particles, titanium oxide particles, silica particles, and talc particles. Non-magnetic components (non-magnetic inorganic compound particles) such as alumina particles, barium sulfate particles, barium carbonate particles, cadmium yellow particles, calcium carbonate particles, and zinc white particles may be used in combination.
When the magnetic substance component and the non-magnetic substance component (non-magnetic inorganic compound particles) are used in combination, the ratio of the magnetic substance component in the mixture thereof is preferably 30% by mass or more.

It is preferable that all or part of the magnetic component is treated with a lipophilic treatment agent.
The lipophilic treatment agent is, for example, an organic having at least one functional group selected from an epoxy group, an amino group, a mercapto group, an organic acid group, an ester group, a ketone group, an alkyl halide group and an aldehyde group. Examples include compounds and mixtures thereof.
As the organic compound having a functional group, a coupling agent is preferable, a silane coupling agent, a titanium coupling agent and an aluminum coupling agent are more preferable, and a silane coupling agent is particularly preferable.

A thermosetting resin is preferable as the resin component constituting the magnetic material dispersion type resin particles.
Examples of the thermosetting resin include phenol resins, epoxy resins, unsaturated polyester resins and the like. Of these, phenolic resins are preferable from the viewpoint of availability (price, ease of manufacture, etc.). Examples of the phenol resin include phenol-formaldehyde resin.
The ratio of the resin component constituting the magnetic material dispersed resin particles to the magnetic material component (or a mixture of the magnetic material component and the non-magnetic material component) is 1% by mass to 20% by mass (magnetic material component). Is preferably 80% by mass to 99% by mass).

Next, a method for producing magnetic material-dispersed resin particles will be described.
Examples of the magnetic material dispersion type resin particles include the methods described in Examples described later. That is, for example, first, phenols and aldehydes are stirred in an aqueous medium in the presence of a magnetic component such as magnetic iron oxide particles and a basic catalyst. Then, phenols and aldehydes are reacted and cured to produce magnetic material-dispersed resin particles containing a magnetic material component such as magnetic iron oxide particles and a phenol resin.
Further, magnetic material dispersed resin particles can also be produced by a method of pulverizing a resin containing a magnetic material component such as magnetic iron oxide particles, a so-called kneading pulverization method.
The former method is preferable from the viewpoint of ease of controlling the particle size of the magnetic carrier and sharpening the particle size distribution of the magnetic carrier.

Next, the porous magnetic core particles will be described.
Examples of the material of the porous magnetic core particles include magnetite and ferrite. Among them, ferrite is preferable from the viewpoint of easy control of the porous structure of the porous magnetic core particles and easy adjustment of the resistance of the porous magnetic core particles.
Ferrite is a sintered body represented by the following general formula.
(M1 ₂ O) _x (M2O) _y (Fe ₂ O ₃ ) _Z
(In the formula, M1 is a monovalent metal, M2 is a divalent metal, and when x + y + z = 1.0, 0 ≦ x ≦ 0.8, 0 ≦ y ≦ 0.8, and 0. 2 <z <1.0.)
In the formula, M1 and M2 include, for example, Li, Fe, Mn, Mg, Sr, Cu, Zn, Ca, Ni, Co, Ba, Y, V, Bi, In, Ta, Zr, B, Mo, Examples thereof include Na, Sn, Ti, Cr, Al, Si and rare earths. Among them, from the viewpoint of maintaining an appropriate amount of magnetization and easily controlling the rate of the ferrite formation reaction, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr-based ferrite, and Li- containing Mn element. Mn-based ferrite is more preferable.

An example of the manufacturing process when ferrite is used as the porous magnetic carrier particles will be described in detail below.
<Process 1 (Weighing / mixing process)>
The ferrite raw material is weighed and mixed.
Examples of the raw material for ferrite include metal particles of the above-mentioned metal elements, oxides thereof, hydroxides, oxalates, carbonates and the like.
Examples of the mixing device include the following. Ball mills, planetary mills, geot mills, vibration mills. Of these, a ball mill is preferable from the viewpoint of mixing.
Specifically, for example, a weighed ferrite raw material and balls are placed in a ball mill, and preferably pulverized and mixed over a period of 0.1 hours or more and 20.0 hours or less.

<Step 2 (temporary firing step)>
The pulverized and mixed ferrite raw material is tentatively calcined in the air or in a nitrogen atmosphere, preferably in a firing temperature range of 700 ° C. or higher and 1200 ° C. or lower, preferably 0.5 hours or longer and 5.0 hours or lower, to be ferrite. Obtain calcined ferrite. For firing, for example, the following furnace is used. Burner type incinerator, rotary type incinerator, electric furnace, etc.

<Step 3 (crushing step)>
The calcined ferrite produced in step 2 is crushed with a crusher.
The crusher is not particularly limited as long as a desired particle size can be obtained. For example, the following can be mentioned. Crusher, hammer mill, ball mill, bead mill, planet mill, geot mill, etc.
In order to obtain a desired particle size of the pulverized ferrite product, for example, when a ball mill or a bead mill is used, it is preferable to control the material, particle size, and operation time of the ball or bead to be used. Specifically, in order to reduce the particle size of the calcined ferrite slurry, balls having a heavy specific gravity may be used or the crushing time may be lengthened. Further, in order to widen the particle size distribution of the calcined ferrite, balls or beads having a heavy specific gravity may be used to shorten the crushing time. Further, by mixing a plurality of calcined ferrites having different particle sizes, it is possible to obtain calcined ferrites having a wide particle size distribution.
Further, when a ball mill or a bead mill is used, a wet type is more preferable than a dry type because the crushed product does not fly up in the mill and the crushing efficiency is high.

<Process 4 (granulation process)>
Water, a binder, and, if necessary, a pore modifier are added to the pulverized product of the calcined ferrite. Examples of the pore adjusting agent include a foaming agent and resin fine particles.
Examples of the foaming agent include sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, ammonium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate and the like.
As the resin fine particles, for example, polyester, polystyrene, styrene-vinyltoluene copolymer, styrene-vinylnaphthalin copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethacryl. Styrene copolymers such as methyl acid acid copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethylketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Combined: Polyvinyl chloride, phenol resin, modified phenol resin, maleine resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin; aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohol And a polyester resin having a monomer selected from diphenols as a structural unit; having a polyurethane resin, a polyamide resin, a polyvinyl butyral, a terpene resin, a kumaron inden resin, a petroleum resin, a polyester unit and a vinyl-based polymer unit. Examples include fine particles of hybrid resin.
As the binder, for example, polyvinyl alcohol is used.
When pulverized in a wet manner in step 3, it is preferable to add a binder and a pore modifier if necessary, considering the water contained in the ferrite slurry.
The obtained ferrite slurry is dried and granulated using a spray dryer, preferably in a warm atmosphere of 100 ° C. or higher and 200 ° C. or lower to obtain a granulated product. The spray dryer is not particularly limited as long as the desired particle size of the porous magnetic core particles can be obtained, but for example, a spray dryer can be used.

<Step 5 (main firing step)>
Next, the granulated product is fired at preferably 800 ° C. or higher and 1400 ° C. or lower, preferably 1 hour or longer and 24 hours or shorter.
By raising the firing temperature and lengthening the firing time, firing proceeds, and as a result, the pore diameter is small and the number of pores is also reduced. By further raising the firing temperature and lengthening the firing time, the pore diameter of the ferrite particles can be made smaller and the number of pores can be made smaller.

<Process 6 (sorting process)>
After crushing the particles obtained by firing as described above, coarse particles and fine particles may be removed by classification or sieving with a sieve, if necessary.
From the viewpoint of suppressing the adhesion of magnetic carriers to the image and suppressing the roughness of the image, the volume distribution standard 50% particle size (D50) of the magnetic core particles is preferably 18.0 μm or more and 68.0 μm or less.

The following step 7 can be performed if necessary.
<Step 7 (filling step)>
Porous magnetic core particles may have low physical strength depending on the internal pore volume. In order to increase the physical strength of the magnetic carrier, at least a part of the voids of the porous magnetic core particles can be filled with resin. The amount of resin filled in the porous magnetic core particles is preferably 2% by mass or more and 15% by mass or less in the porous magnetic core particles.
If there is little variation in the resin content of each magnetic carrier, even if only a part of the internal voids is filled with the resin, the resin is filled only in the voids near the surface of the porous magnetic core particles and the voids remain inside. Alternatively, the internal voids may be completely filled with resin.
The method of filling the voids of the porous magnetic core particles with the resin is not particularly limited, but the porous magnetic core particles are made into a resin solution by a coating method such as a dipping method, a spray method, a brush coating method, and a fluidized bed. A method of impregnating and then volatilizing the solvent can be mentioned. Further, a method of diluting the resin with a solvent and adding the resin to the voids of the porous magnetic core particles can also be adopted.
As the resin to be filled in the voids of the porous magnetic core particles, either a thermoplastic resin or a thermosetting resin may be used. It is preferable that the affinity for the porous magnetic core particles is high. When a resin having a high affinity is used, the surface of the porous magnetic core particles can be covered with the resin at the same time as filling the voids of the porous magnetic core particles with the resin.
Examples of the resin to be filled include the following as the thermoplastic resin. Novolac resin, saturated alkyl polyester resin, polyarylate, polyamide resin, acrylic resin, etc.
Further, examples of the thermosetting resin include the following. Phenolic resins, epoxy resins, unsaturated polyester resins, silicone resins, etc.

Further, the magnetic carrier has a resin coating layer formed on the surface of the magnetic carrier core.
The method of coating the surface of the magnetic carrier core with a resin is not particularly limited, and examples thereof include a method of coating by a dipping method, a spray method, a brush coating method, a dry method, and a coating method such as a fluidized bed.
Specifically, for example, the surface of the magnetic carrier core can be coated with the resin by putting the magnetic carrier core and the resin solution into a mixer and mixing them.
The amount of resin to be charged is preferably 0.1 part by mass to 10.0 parts by mass (converted to resin solid content) with respect to 100.0 parts by mass of the magnetic carrier core. The concentration of the resin component in the resin solution is preferably 1 to 10%. Further, the solvent in the resin solution is not particularly limited, but toluene is preferable from the viewpoint of efficiency of solvent removal.
As the mixer, for example, a planetary motion type mixer such as Nautamixer VN type (Hosokawa Micron Co., Ltd.) can be used. The time for mixing the magnetic carrier core and the resin solution in the mixer can be, for example, 10 minutes to 90 minutes. Further, the temperature of the mixer can be set to, for example, 40 ° C to 90 ° C.
The magnetic carrier core whose surface is coated with the resin can be dried, for example, at a temperature of 130 ° C. to 230 ° C. for 0.5 to 4.0 hours to obtain a magnetic carrier.

When the obtained magnetic carrier is further coated with a resin, the magnetic carrier can be further coated with a resin in the same manner as described above except that the magnetic carrier core is replaced with the magnetic carrier obtained above.

Further, the resin coating layer may contain particles having conductivity or particles or materials having charge controllability. Examples of the conductive particles include carbon black, magnetite, graphite, zinc oxide, tin oxide and the like.
The content of the conductive particles is preferably 0.1 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the coating resin from the viewpoint of adjusting the resistance of the magnetic carrier.
Particles having charge controllability include organic metal complex particles, organic metal salt particles, chelate compound particles, monoazo metal complex particles, acetylacetone metal complex particles, hydroxycarboxylic acid metal complex particles, and polycarboxylic acid metal. Complex particles, polyol metal complex particles, polymethylmethacrylate resin particles, polystyrene resin particles, melamine resin particles, phenol resin particles, nylon resin particles, silica particles, titanium oxide particles, alumina particles, etc. Can be mentioned.
The content of the particles having charge controllability is preferably 0.5 parts by mass or more and 50.0 parts by mass or less with respect to 100 parts by mass of the coating resin from the viewpoint of adjusting the triboelectric charge amount.

Next, the composition of the preferable toner will be described in detail below.
The toner has toner particles containing a binder resin. Examples of the binder resin include vinyl resin, polyester resin, epoxy resin and the like. Among them, vinyl resin and polyester resin are more preferable, and polyester resin is particularly preferable, from the viewpoint of chargeability and fixability.

Monopolymers or copolymers of vinyl-based monomers, polyesters, polyurethanes, epoxy resins, polyvinyl butyral, rosin, modified rosins, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, etc. , If necessary, it can be mixed with the binder resin and used.
When two or more kinds of resins are mixed and used as a binder resin, it is preferable to mix those having different molecular weights in an appropriate ratio.

As the binder resin, the polyester resin shown below is also preferable.
Based on all the monomer units constituting the polyester resin, it is preferable that 45 mol% or more and 55 mol% or less is an alcohol component, and 45 mol% or more and 55 mol% or less is an acid component.
The acid value of the polyester resin is preferably 0 mgKOH / g or more and 90 mgKOH / g or less, and more preferably 5 mgKOH / g or more and 50 mgKOH / g or less. The hydroxyl value of the polyester resin is preferably 0 mgKOH / g or more and 50 mgKOH / g or less, and more preferably 5 mgKOH / g or more and 30 mgKOH / g or less. When the acid value and the hydroxyl value of the polyester resin are within the above ranges, the environmental dependence of the charging characteristics of the toner becomes small.
The glass transition temperature (Tg) of the polyester resin is preferably 50 ° C. or higher and 75 ° C. or lower, and more preferably 55 ° C. or higher and 65 ° C. or lower. The number average molecular weight (Mn) of the polyester resin is preferably 1500 or more and 50,000 or less, and more preferably 2000 or more and 20000 or less. The weight average molecular weight (Mw) of the polyester resin is preferably 6000 or more and 150,000 or less, and more preferably 10,000 or more and 100,000 or less.
The content of the polyester resin in the binder resin is preferably 50% by mass to 100% by mass, more preferably 80% by mass to 100% by mass.

The following crystalline polyester resin may be added to the toner particles for the purpose of promoting the plasticizing effect of the toner and improving the low temperature fixability.
Examples of the crystalline polyester resin include a polycondensate of a monomer composition containing an aliphatic diol having 2 to 22 carbon atoms and an aliphatic dicarboxylic acid having 2 to 22 carbon atoms as main components. ..
The aliphatic diol having 2 or more and 22 or less carbon atoms (more preferably 6 or more and 12 or less carbon atoms) is not particularly limited, but is preferably a chain-like (more preferably linear) aliphatic diol. Among these, linear aliphatics such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol, α, ω-diol are preferably exemplified.
Of the alcohol components, preferably 50% by mass or more, more preferably 70% by mass or more, is an alcohol selected from an aliphatic diol having 2 or more and 22 or less carbon atoms.
A polyhydric alcohol monomer other than the aliphatic diol can also be used. Examples of the divalent alcohol monomer include aromatic alcohols such as polyoxyethylene bisphenol A and polyoxypropylene bisphenol A; 1,4-cyclohexanedimethanol and the like.
As the trihydric or higher polyhydric alcohol monomer, aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1, , 2,5-Pentantriol, glycerin, 2-methylpropantriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, aliphatic alcohols such as trimethylrolpropane and the like.
Further, monovalent alcohol may be used to the extent that the characteristics of the crystalline polyester resin are not impaired.

On the other hand, the aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms (more preferably 6 or more and 12 or less carbon atoms) is not particularly limited, but is a chain (more preferably linear) aliphatic dicarboxylic acid. Is preferable. Hydrolyzed amounts of these acid anhydrides or lower alkyl esters are also included.
Of the carboxylic acid components, preferably 50% by mass or more, more preferably 70% by mass or more is a carboxylic acid selected from aliphatic dicarboxylic acids having 2 or more and 22 or less carbon atoms.
A multivalent carboxylic acid other than the above-mentioned aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms can also be used. Examples of the divalent carboxylic acid include aromatic carboxylic acids such as isophthalic acid and terephthalic acid; aliphatic carboxylic acids such as n-dodecylsuccinic acid and n-dodecenylsuccinic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. These acid anhydrides or lower alkyl esters are also included.
Examples of trivalent or higher polyvalent carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and pyromerit. Aromatic carboxylic acids such as acids, 1,2,4-butanetricarboxylic acids, 1,2,5-hexanetricarboxylic acids, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, and other aliphatic carboxylic acids. Examples include acids, and derivatives such as these acid anhydrides or lower alkyl esters are also included.
Further, it may contain a monovalent carboxylic acid to the extent that the characteristics of the crystalline polyester resin are not impaired.

The crystalline polyester resin can be produced according to a conventional polyester synthesis method. For example, the carboxylic acid monomer and the alcohol monomer are subjected to an esterification reaction or a transesterification reaction, and then polycondensation reaction is carried out under reduced pressure or by introducing nitrogen gas according to a conventional method to obtain a desired crystal. A sex polyester resin can be obtained.
The amount of the crystalline polyester resin used is preferably 0.1 part by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the binder resin. It is preferably 3 parts by mass or more and 15 parts by mass or less.

The toner particles may have a colorant. Examples of the colorant include, but are not limited to, the following.
Examples of the black colorant include those adjusted to black using carbon black; a yellow colorant, a magenta colorant, and a cyan colorant.
Examples of the coloring pigment for magenta toner include the following. Condensed azo compound, diketopyrrolopyrrole compound, anthracinone compound, quinacridone compound, basic dye lake compound, naphthol compound, benzimidazolone compound, thioindigo compound, perylene compound. Specifically, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 57: 1, 58, 60, 63, 64, 68, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221 238, 254, 269; C.I. I. Pigment Violet 19, C.I. I. Bat Red 1, 2, 10, 13, 15, 23, 29, 35.
As the colorant, the pigment may be used alone, or the dye and the pigment may be used in combination.
Examples of the magenta toner dye include the following. C. I Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disperse Thread 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27, C.I. I. Oil-soluble dyes such as Disperse Violet 1, C.I. I.
Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, C.I. I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.
Examples of the coloring pigment for cyan toner include the following. C. I. Pigment Blue 1, 2, 3, 7, 15: 2, 15: 3, 15: 4, 16, 17, 60, 62, 66; C.I. I. Bat Blue 6, C.I. I. Acid blue 45, a copper phthalocyanine pigment in which 1 to 5 phthalocyanine methyls are substituted in the phthalocyanine skeleton.
Examples of the yellow coloring pigment include the following. Condensed azo compound, isoindolinone compound, anthraquinone compound, azo metal compound, methine compound, allylamide compound. Specifically, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 155, 168, 174, 180, 181; 185, 191; C.I. I. Bat Yellow 1, 3, 20 can be mentioned. In addition, C.I. I. Direct green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as Basic Green 6 and Solvent Yellow 162 can also be used.
The content of the colorant is preferably 0.1 part by mass or more and 30 parts by mass or less, more preferably 0.5 part by mass or more and 20 parts by mass or less, more preferably, with respect to 100 parts by mass of the binder resin. Is 3 parts by mass or more and 15 parts by mass or less.

The method for producing the toner particles is not particularly limited, and a known method can be adopted. Examples of the production method include a melt-kneading method, a suspension polymerization method, a dissolution-suspension method, and an emulsification / agglutination method.
Further, it is preferable to use the toner particles in which a colorant is mixed with the binder resin in advance to form a masterbatch. Then, by melt-kneading the colorant masterbatch and other raw materials (binding resin, wax, etc.), the colorant can be satisfactorily dispersed in the toner particles.

In order to further stabilize the chargeability of the toner, a charge control agent can be used if necessary. The charge control agent is preferably used in an amount of 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the binder resin. When it is 0.5 parts by mass or more, sufficient charging characteristics can be obtained. On the other hand, when it is 10 parts by mass or less, the compatibility with other materials becomes good, and excessive charging under low humidity can be suppressed.
Examples of the charge control agent include, but are not limited to, the following.
For example, an organometallic complex or a chelate compound is effective as a load electrical control agent for controlling the toner to load electrical. Specific examples thereof include monoazo metal complexes, aromatic hydroxycarboxylic acid metal complexes, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides thereof, or esters thereof, and phenol derivatives of bisphenol.
Examples of the positive charge control agent for controlling the toner to positive charge include modified products of niglosin and fatty acid metal salts, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate and the like. Triphenylmethane dyes and rake pigments thereof (as rake agents, phosphotungstate acid, phosphomolybdic acid, phosphotungenentic acid) Molybdenum acid, tannic acid, lauric acid, galvanic acid, ferricyanic acid, ferrocyanic compounds, etc.), as metal salts of higher fatty acids, diorganosin oxide such as dibutyltin oxide, dioctylstinoxide, dicyclohexylstinoxide, dibutyltinborate, dioctyl Examples thereof include diorgano sulpates such as sulphonate and dicyclohexyl sulphate.

If necessary, one or more release agents may be contained in the toner particles. Examples of the release agent include, but are not limited to, the following.
Aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax can be preferably used. In addition, oxides of aliphatic hydrocarbon waxes such as polyethylene oxide wax or block copolymers thereof; waxes containing fatty acid esters such as carnauba wax, sazole wax, and montanic acid ester wax as main components; and Deoxidized fatty acid esters such as carnauba wax are partially or wholly deoxidized.
The content of the release agent is preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the binder resin.
Further, the melting point defined by the maximum endothermic peak temperature at the time of temperature rise measured by the differential scanning calorimeter (DSC) of the release agent is preferably 65 ° C. or higher and 130 ° C. or lower. More preferably, it is 80 ° C. or higher and 125 ° C. or lower. When the melting point is 65 ° C. or higher, the viscosity of the toner becomes suitable, so that the adhesion of the toner to the photoconductor can be suppressed. On the other hand, when the melting point is 130 ° C. or lower, the low temperature fixability becomes good.

As the toner, a fine powder which can increase the fluidity when compared before and after the addition by externally adding to the toner particles may be used as the fluidity improver. For example, fluororesin powder such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; fine powder silica such as wet manufacturing silica and dry manufacturing silica, fine powder titanium oxide, fine powder alumina and the like as a silane coupling agent. , Titanium coupling agent, silicone oil, surface treatment and hydrophobization treatment, and treatment so that the degree of hydrophobicity measured by the methanol titration test shows a value in the range of 30 to 80 is particularly preferable. ..
The fluidity improver is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 0.2 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the toner particles.

The two-component developer of the present invention contains a toner having toner particles containing a binder resin and a magnetic carrier.
When the toner is mixed with the magnetic carrier, the magnetic carrier mixing ratio at that time is preferably 2% by mass or more and 15% by mass or less, and more preferably 4% by mass or more and 13% by mass or less as the toner concentration in the developing agent. Good results are usually obtained. When the toner concentration is 2% by mass or less, the image density is good, and when it is 15% by mass or less, fog and scattering of toner in the developing device can be suppressed.

The two-component developer containing the magnetic carrier of the present invention
Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing step of developing the electrostatic latent image with a two-component developer to form a toner image.
It can be used in an image forming method having a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.

Further, in the image forming method, the developer has a two-component developer, and the replenishing developer is replenished to the developer in accordance with the reduction in the toner concentration of the two-component developer in the developer. It may have such a configuration. The magnetic carrier of the present invention can be used as a replenishing developer for use in such an image forming method. The image forming method may have a configuration in which excess magnetic carriers in the developing device are discharged from the developing device as needed.

That is, the replenishing developer of the present invention is
Charging process for charging the electrostatic latent image carrier,
Electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing process in which the electrostatic latent image is developed using a two-component developer in a developing device to form a toner image.
It has a transfer step of transferring the toner image to the transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
A replenishing developer for use in an image forming method in which a replenishing developer is replenished to the developing device in response to a decrease in the toner concentration of the two-component developing agent in the developing device.
The replenishing developer contains a magnetic carrier and a toner having toner particles containing a binder resin.
The replenishing developer contains 2 parts by mass or more and 50 parts by mass or less of the toner with respect to 1 part by mass of the magnetic carrier.
The magnetic carrier is the magnetic carrier of the present invention.

The replenishing developer of the present invention
Charging process for charging the electrostatic latent image carrier,
Electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing process in which the electrostatic latent image is developed using a two-component developer in a developing device to form a toner image.
It has a transfer step of transferring the toner image to the transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
The replenishing developer can be used in the image forming method in which the replenishing developer is replenished to the developing device according to the reduction in the toner concentration of the two-component developing agent in the developing device.

Next, an image forming apparatus including a developing apparatus using a magnetic carrier, a two-component developer, and a supplementary developer will be described with reference to the present invention, but the present invention is not limited thereto.
<Magnetic carrier>
FIG. 1 shows a cross section of the magnetic carrier of the present invention and a schematic view of measurement positions by X-ray photoelectron spectroscopy. The magnetic carrier of the present invention has a magnetic carrier core 19 and a resin coating layer formed on the surface of the magnetic carrier core 19. The resin coating layer has a first resin coating layer 18 formed on the magnetic carrier core and a second resin coating layer 17 further formed on the first resin coating layer 18.
The first resin coating layer 18 has a structure represented by the above formula (1), and the structure represented by the formula (1) contains a nitrogen atom 21 derived from a quaternary ammonium salt. Among the nitrogen atoms derived from the quaternary ammonium salt in the magnetic carrier, the ratio of the nitrogen atoms present on the surface of the magnetic carrier is N1 (mass%). Further, among the nitrogen atoms derived from the quaternary ammonium salt in the magnetic carrier, the ratio of the nitrogen atoms at a position at a distance of 0.95 × d (μm) from the surface of the magnetic carrier to the magnetic carrier core in the depth direction is N2 ( Mass%). Here, d is the layer thickness (unit: μm) of the resin coating layer.

<Image formation method>
In FIG. 2, the electrostatic latent image carrier 1 rotates in the direction of the arrow in the figure. The electrostatic latent image carrier 1 is charged by a charger 2 which is a charging means, and the surface of the charged electrostatic latent image carrier 1 is exposed by an exposure device 3 which is an electrostatic latent image forming means. Form an image. The developer 4 has a developing container 5 for accommodating a two-component developer, the developer carrier 6 is arranged in a rotatable state, and a magnet 7 is provided inside the developer carrier 6 as a magnetic field generating means. It is included. At least one of the magnets 7 is installed so as to face the latent image carrier.
The two-component developer is held on the developer carrier 6 by the magnetic field of the magnet 7, and the amount of the two-component developer is regulated by the regulating member 8 so that the developing unit faces the electrostatic latent image carrier 1. Be transported. In the developing unit, a magnetic brush is formed by the magnetic field generated by the magnet 7. After that, the electrostatic latent image is visualized as a toner image by applying a development bias formed by superimposing an alternating electric field on the DC electric field. The toner image formed on the electrostatic latent image carrier 1 is electrostatically transferred to the recording medium 12 by the transfer charger 11.
Here, as shown in FIG. 3, the electrostatic latent image carrier 1 may be temporarily transferred to the intermediate transfer body 9, and then electrostatically transferred to the transfer material (recording medium) 12. After that, the recording medium 12 is conveyed to the fixing device 13, where the toner is fixed on the recording medium 12 by heating and pressurizing. After that, the recording medium 12 is discharged to the outside of the device as an output image. After the transfer step, the toner remaining on the electrostatic latent image carrier 1 is removed by the cleaner 15.
After that, the electrostatic latent image carrier 1 cleaned by the cleaner 15 is electrically initialized by light irradiation from the pre-exposure 16, and the image forming operation is repeated.

FIG. 3 shows an example of a schematic diagram in which the image forming method of the present invention is applied to a full-color image forming apparatus.
The arrows indicating the arrangement and rotation direction of the image forming units such as K, Y, C, and M in the drawing are not limited thereto. By the way, K means black, Y means yellow, C means cyan, and M means magenta. In FIG. 3, the electrostatic latent image carriers 1K, 1Y, 1C, and 1M rotate in the direction of arrows in the figure. Each electrostatic latent image carrier is charged by a charger 2K, 2Y, 2C, 2M which is a charging means, and on the surface of each charged electrostatic latent image carrier, an exposure device 3K which is an electrostatic latent image forming means, It is exposed by 3Y, 3C, and 3M to form an electrostatic latent image.
After that, the electrostatic latent image can be used as a toner image by the two-component developer supported on the developer carriers 6K, 6Y, 6C, and 6M provided in the developing units 4K, 4Y, 4C, and 4M, which are the developing means. It is visualized. Further, it is transferred to the intermediate transfer body 9 by the intermediate transfer chargers 10K, 10Y, 10C, and 10M which are transfer means. Further, it is transferred to the recording medium 12 by the transfer charger 11 which is a transfer means, and the recording medium 12 is fixed by heating pressure by the fixing device 13 which is a fixing means and is output as an image. Then, the intermediate transfer body cleaner 14, which is a cleaning member of the intermediate transfer body 9, collects the transfer residual toner and the like.

Specifically, as a developing method, it is preferable to apply an AC voltage to the developer carrier to form an alternating electric field in the developing region and perform development in a state where the magnetic brush is in contact with the photoconductor. .. The distance (distance between SD) between the developer carrier (development sleeve) 6 and the photosensitive drum is 100 μm or more and 1000 μm or less, which is good for preventing magnetic carrier adhesion and improving dot reproducibility. When it is 100 μm or more, the developer is sufficiently supplied and the image density becomes good. When it is 1000 μm or less, the magnetic field lines from the magnetic pole S1 are hard to spread, the density of the magnetic brush becomes good, and the dot reproducibility is improved. In addition, the force for restraining the magnetic carrier is increased, and the adhesion of the magnetic carrier can be suppressed.
The voltage (Vpp) between the peaks of the alternating electric field is preferably 300 V or more and 3000 V or less, and more preferably 500 V or more and 1800 V or less. The frequency is preferably 500 Hz or more and 10000 Hz or less, more preferably 1000 or more and 7000 Hz or less, and can be appropriately selected and used depending on the process. In this case, examples of the AC bias waveform for forming the alternating electric field include a triangular wave, a square wave, a sine wave, and a waveform in which the duty ratio is changed.
In order to cope with the change in the formation rate of the toner image, it is preferable to apply a development bias voltage (intermittent alternating superimposition voltage) having a discontinuous AC bias voltage to the developer carrier for development. When the applied voltage is 300 V or more, it is easy to obtain a sufficient image density, and it is easy to collect the fog toner in the non-image portion. Further, when the voltage is 3000 V or less, the latent image is less likely to be disturbed through the magnetic brush, and good image quality can be easily obtained.

By using a two-component developer having a well-charged toner, the fog removal voltage (Vback) can be lowered, and the primary charge of the photoconductor can be lowered, so that the life of the photoconductor is extended. it can. The Vback is preferably 200 V or less, more preferably 150 V or less, although it depends on the developing system. As the contrast potential, 100 V or more and 400 V or less are preferably used so as to obtain a sufficient image density.
Further, although it is related to the process speed, the configuration of the electrostatic latent image-bearing photoconductor is usually the same as that of the photoconductor used in the image forming apparatus. For example, a photoconductor having a structure in which a conductive layer, an undercoat layer, a charge generation layer, a charge transport layer, and a charge injection layer, if necessary, are sequentially provided on a conductive substrate such as aluminum or SUS can be mentioned.
The conductive layer, the undercoat layer, the charge generation layer, and the charge transport layer may be those usually used for a photoconductor. As the outermost surface layer of the photoconductor, for example, a charge injection layer or a protective layer may be used.

Hereinafter, a method for measuring physical properties according to the present invention will be described.
<Measuring method of volume average particle size (D50) of magnetic carrier core>
The particle size distribution is measured by a laser diffraction / scattering type particle size distribution measuring device "Microtrack MT3300EX" (manufactured by Nikkiso Co., Ltd.).
The volume average particle size (D50) of the magnetic carrier core is measured by mounting a sample feeder "One Shot Dry Sample Conditioner Turbotrac" (manufactured by Nikkiso Co., Ltd.) for dry measurement. As the supply condition of Turbotrac, a dust collector is used as a vacuum source, the air volume is about 33 L / sec, and the pressure is about 17 kPa. Control is done automatically on the software. For the particle size, the 50% particle size (D50), which is the cumulative value of the volume average, is determined. Control and analysis are performed using the attached software (version 10.3.3-202D). The measurement conditions are as follows.
SetZero time: 10 seconds Measurement time: 10 seconds Number of measurements: 1 time Particle refractive index: 1.81%
Particle shape: Non-spherical measurement upper limit: 1408 μm
Lower limit of measurement: 0.243 μm
Measurement environment: 23 ° C, 50% RH

<Method of confirming the structures represented by the formulas (1) to (7) in the first resin coating layer and the second resin coating layer>
When the first resin coating layer is a thermosetting resin, the second resin coating layer is separated from the magnetic carrier by the following method to determine whether or not it has the structures represented by the formulas (1) to (7). Can be done.
As a method of separating the second resin coating layer from the magnetic carrier, there is a method of eluting the resin constituting the second resin coating layer by taking 10 g of the magnetic carrier in a cup and stirring with 10 mL of toluene. ..
The resin constituting the second resin coating layer separated by the above method is dissolved in chloroform-D, and ¹³ C-NMR is measured. ¹³ The measurement conditions of C-NMR are as follows.
(Measurement condition)
Equipment: ECA-400 (400MHz) manufactured by JEOL Ltd.
The measurement is carried out at 25 ° C. in a deuterated solvent containing tetramethylsilane as an internal standard substance. The chemical shift value is shown as a ppm shift value (δ value) with tetramethylsilane, which is an internal standard substance, as 0.

The structure of the first resin coating layer remaining on the magnetic carrier core is specified by a pyrolysis gas chromatography-mass spectrometer (hereinafter, pyrolysis GC-MS).
(Measurement condition)
As the apparatus, "PYROFOIL SAMPLER JPS-700" manufactured by Nippon Analytical Industry Co., Ltd. is used, and as the gas chromatography mass spectrometer, "Trace GCMS" manufactured by Thermo Fisher Scientific Co., Ltd. is used. For the sample, 0.1 mg of the sample is wrapped in pyrofoil at 590 ° C. and set in a pyrolyzer. As the GC-MS conditions, the column used is "HP-INNOWAX" manufactured by Agilent Technologies, with a column length of 30 m, an inner diameter of 0.25 mm, and a liquid phase of 0.25 μm. The column temperature rise conditions are 5 ° C./min from 50 ° C. to 120 ° C., 10 ° C./min up to 200 ° C., and 3 min at 200 ° C. The conditions of the injection port of GC-MS are the injection port temperature of 200 ° C., split analysis, split flow of 50 mL / min, and injection port pressure of 100 kPa.

When the first resin coating layer is a thermoplastic resin, the coating resin is eluted by taking 10 g of a magnetic carrier in a cup and stirring with 10 mL of toluene. The eluted resin components include a resin constituting the first resin coating layer and a resin constituting the second resin coating layer. In that case, the eluted resin is ^{measured by 13} C-NMR and thermal decomposition GC-MS by the same method as described above, and the structure is specified.

<Measuring method of weight average particle size (D4) and number average particle size (D1)>
The weight average particle size (D4) and the number average particle size (D1) of the toner particles are the precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, Beckman) by the pore electric resistance method equipped with an aperture tube of 100 μm. -Use the attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting measurement conditions and analyzing measurement data. Measure with 25,000 effective measurement channels, analyze the measurement data, and calculate.
The electrolytic aqueous solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water so that the concentration becomes about 1% by mass. Specifically, "ISOTON II" (manufactured by Beckman Coulter) is used. To do. Before performing measurement and analysis, set the dedicated software as follows.
In the dedicated software "Change standard measurement method (SOM) screen", set the total count number in the control mode to 50,000 particles, set the number of measurements once, and set the Kd value to "standard particles 10.0 μm" (Beckman Coulter). The value obtained using (manufactured by) is set. By pressing the threshold / noise level measurement button, the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, and the electrolyte to ISOTON II, and check the flush of the aperture tube after measurement.
In the "pulse to particle size conversion setting screen" of the dedicated software, the bin spacing is set to logarithmic particle size, the particle size bin is set to 256 particle size bins, and the particle size range is set from 2 μm to 60 μm.

The specific measurement method is as follows.
(1) Approximately 200 ml of the electrolytic aqueous solution is placed in a 250 ml round bottom beaker made of glass dedicated to Multisizer 3 and set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "flash of the aperture tube" function of the dedicated software.
(2) Put about 30 ml of the electrolytic aqueous solution in a 100 ml flat bottom beaker made of glass. Among them, as a dispersant, "Contaminone N" (a 10% by mass aqueous solution of a neutral detergent for cleaning a precision measuring instrument with a pH of 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd. ) Is diluted 3 times by mass with ion-exchanged water, and about 0.3 ml of the diluted solution is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with the phase shifted by 180 degrees, and are installed in the water tank of the ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios) with an electrical output of 120 W. Add a predetermined amount of ion-exchanged water. About 2 ml of the contaminanton N is added to this water tank.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.
(5) In a state where the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves, about 10 mg of toner particles are added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion processing is continued for another 60 seconds. In ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10 ° C. or higher and 40 ° C. or lower.
(6) Using a pipette, the electrolytic aqueous solution of (5) in which toner particles are dispersed is dropped onto the round bottom beaker of (1) installed in the sample stand, and the measured concentration is adjusted to about 5%. To do. Then, the measurement is performed until the number of measurement particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the device, and the weight average particle diameter (D4) and the number average particle diameter (D1) are calculated. When the graph / volume% is set in the dedicated software, the "average diameter" of the analysis / volume statistics (arithmetic mean) screen is the weight average particle size (D4), and the graph / number% is set in the dedicated software. The "average diameter" on the analysis / number statistical value (arithmetic mean) screen is the number average particle size (D1).

<Calculation method of fine powder amount>
The number-based fine powder amount (number%) in the toner particles is calculated as follows.
The percentage of particles having a size of 3.0 μm or less in the toner particles is determined after the measurement of Multisizer 3 is performed.
(1) Set the graph / number% with the dedicated software and display the chart of the measurement result as the number%. (2) Check "<" in the particle size setting part on the format / particle size / particle size statistics screen, and enter "3" in the particle size input section below it. And
(3) The numerical value of the "<3 μm" display unit when the analysis / number statistical value (arithmetic mean) screen is displayed is the percentage of the number of particles of 3.0 μm or less in the toner particles.

<Calculation method of coarse powder amount>
The volume-based crude powder amount (volume%) in the toner particles is calculated as follows.
The volume% of the particles of 10.0 μm or more in the toner particles is determined after the measurement of Multisizer 3 described above.
(1) Set the graph / volume% with the dedicated software and display the measurement result chart in volume%. (2) Check ">" in the particle size setting part on the format / particle size / particle size statistics screen, and enter "10" in the particle size input section below it. And
(3) The numerical value of the "> 10 μm" display unit when the analysis / volume statistical value (arithmetic mean) screen is displayed is the volume% of the particles of 10.0 μm or more in the toner particles.

<Measurement method of N1 and N2 by XPS>
As a measurement sample, an indium foil is attached on an XPS-dedicated platen, and a magnetic carrier is attached on the indium foil. At that time, the particles are evenly attached so that the indium foil portion is not exposed. The X-ray irradiation site and the sputtering site by GCIB irradiation are set as carriers on the indium foil by the following XPS device.
Equipment used: PHI5000 VersaProbe II manufactured by ULVAC-PHI
Irradiation line: Al-Kα line Beam diameter: 100 μm
Output: 25W15kV
Photoelectron uptake angle: 45 °
Pass Energy: 58.70 eV
Stepsize: 0.125 eV
XPS peaks: C2p, O2p, Si2p, N1s, Fe2p
Measurement range: 300 μm x 200 μm
GUN type: GCIB
Time: 15min
Interval: 1min
SputterSetting: 20kV
The measurement is performed under the above conditions, and the element number ratio (atomic%) is calculated from the peak of each element.
The element number ratio of the nitrogen element in the above five elements on the surface of the magnetic carrier is n1. Further, it is assumed that the layer thickness d (μm) is reached from the surface of the magnetic carrier when the ratio of the number of elements derived from Fe2p becomes 1.0 (atomic%) or more by sputtering, and the number of sputterings at that time is 0. Let n2 be the result of the measured value at the time of .95 times.
The measurement locations are randomly changed, and n1 and n2 are measured 10 times in total, and the average values of the respective values are N1 and N2.
Further, the rate of the depth of one sputtering can be calculated based on the layer thickness d measured by the method shown later.

<Measuring method of layer thickness d of resin coating layer>
The thickness d of the resin coating layer is measured by observing the cross section of the magnetic carrier with a transmission electron microscope (TEM) (50,000 times each) and measuring the thickness of the resin coating layer.
Specifically, the magnetic carrier is ion-milled using an argon ion milling device (manufactured by Hitachi High-Technologies Corporation, trade name E-3500), and the magnetic carrier cross section is subjected to a transmission electron microscope (TEM) (50,000 times each). The thickness of the resin coating layer of No. 1 is arbitrarily measured at 10 points.
The same measurement as above is performed on 20 magnetic carriers, and the average value of 200 measured values of the thickness of the obtained resin coating layer is d (μm). The ion milling measurement conditions are as follows.
Beam diameter: 400 μm (half width)
Ion gun acceleration voltage: 5kV
Ion gun discharge voltage: 4kV
Ion gun discharge current: 463 μA
Ion gun irradiation current amount: 90μA ^/ cm 3 ^/ 1min

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Parts in the following formulations are mass-based unless otherwise noted.

<Production example of solutions of coating resins A-1 to A-6, B-1 to B-2, C-1 to C-5, and D-1>
The raw materials shown in Table 1 (100 parts in total) were added to a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube and a ground-glass stirrer, and further 200.0 parts of toluene and 200.0 parts of methyl ethyl ketone were added. A part, 4.0 parts of azobisisovaleronitrile was added, and the mixture was kept at 80 ° C. for 10 hours under a nitrogen stream to obtain a solution of the coating resin A-1 (solid content: 20% by mass).
Further, using the raw materials shown in Tables 1 to 4, the coating resins A-2 to A-6, B-1 to B-2, and C-1 to C are similarly adjusted except that the reaction time and temperature are adjusted. Each solution of -5 and D-1 was obtained.

［化合物Ａ］

［化合物Ｂ］

[Compound A]

[Compound B]

The abbreviations in the table are as follows.
DMC: Dimethylaminoethyl methacrylate / Methyl quaternary salt GMA: Glycidyl methacrylate St: Styrene 2HEMA: 2-Hydroxyethyl methacrylate MAA: Methacrylic acid Man: Maleic anhydride MMA: Methyl methacrylate CHMA: Cyclohexyl methacrylate Also, macromonomers in the table. A is represented by the following formula (M), and M'in the formula (M) is a methyl methacrylate polymer represented by the following formula (M'), and the weight average molecular weight Mw of the macromonomer A is 5000. is there.

<Manufacturing example of magnetic carrier core 1>
Process 1 (Weighing / mixing process)
Fe ₂ O ₃ 68.3% by mass
MnCO ₃ 28.5% by mass
Mg (OH) ₂ 2.0% by mass
SrCO ₃ 1.2% by mass
The above ferrite raw materials were weighed, 20 parts of water was added to 80 parts of the ferrite raw material, and then wet mixing was performed with a ball mill for 3 hours using zirconia having a diameter (φ) of 10 mm to prepare a slurry. The solid content concentration of the slurry was 80% by mass.
Step 2 (temporary firing step)
After drying the mixed slurry with a spray dryer (manufactured by Okawara Kakoki Co., Ltd.), it is calcined in a batch electric furnace under a nitrogen atmosphere (oxygen concentration 1.0% by volume) at a temperature of 1050 ° C. for 3.0 hours. Ferrite was prepared.
Process 3 (crushing process)
After crushing the calcined ferrite to about 0.5 mm with a crusher, water was added to prepare a slurry. The solid content concentration of the slurry was 70% by mass. A slurry was obtained by pulverizing with a wet ball mill using 1/8 inch stainless beads for 3 hours. Further, this slurry was pulverized for 4 hours with a wet bead mill using zirconia having a diameter of 1 mm to obtain a calcined ferrite slurry having a volume-based 50% particle size (D50) of 1.3 μm.
Process 4 (granulation process)
To 100 parts of the calcined ferrite slurry, 1.0 part of ammonium polycarboxylic acid as a dispersant and 1.5 parts of polyvinyl alcohol as a binder were added, and then granulated into spherical particles with a spray dryer (manufactured by Okawara Kakoki Co., Ltd.). , Dried. After adjusting the particle size of the obtained granulated product, it was heated at 700 ° C. for 2 hours using a rotary electric furnace to remove organic substances such as dispersants and binders.
Step 5 (firing step)
Under a nitrogen atmosphere (oxygen concentration 1.0% by volume), the time from room temperature to the firing temperature (1300 ° C.) was set to 2 hours, and the temperature was maintained at 1300 ° C. for 5 hours for firing. Then, the temperature was lowered to 60 ° C. over 8 hours, returned to the atmosphere from the nitrogen atmosphere, and taken out at a temperature of 40 ° C. or lower.
Process 6 (sorting process)
After crushing the agglomerated particles, coarse particles were removed by sieving with a sieve having a mesh size of 150 μm, fine particles were removed by wind power classification, and non-magnetic substances were removed using a magnetic beneficiation machine. Further, coarse particles were removed with a vibrating sieve to obtain a magnetic carrier core 1 having a D50 of 34 μm.

<Manufacturing example of magnetic carrier core 2>
4.0 parts of a silane-based coupling agent (3- (2-aminoethylamino) propyltrimethoxysilane) was added to 100.0 parts of magnetite powder having an average particle size of 0.30 μm, and the mixture was placed in a container. Fine particles were treated by mixing and stirring at high speed at 100 ° C. or higher.
・ Phenol 10 parts ・ Formaldehyde solution 6 parts (formaldehyde 40%, methanol 10%, water 50%)
-84 parts of treated magnetite Put the above material, 5 parts of 28% ammonia water and 20 parts of water in a flask, heat and hold to 85 ° C in 30 minutes while stirring and mixing, and polymerize for 3 hours to produce. The phenolic resin was cured. Then, the cured phenol resin was cooled to 30 ° C., water was further added, the supernatant was removed, the precipitate was washed with water, and then air-dried. Next, this was dried under reduced pressure (5 mmHg or less) at a temperature of 60 ° C. to obtain a spherical magnetic carrier core 2 having a D50 of 35 μm in a state in which the magnetic material was dispersed.

<Manufacturing example of magnetic carrier 1>
<Formation of first resin coating layer>
The coating resin A-1 solution and the coating resin B-1 solution were mixed at the ratios shown in Table 5, diluted with toluene so that the resin component was 5%, and the sufficiently stirred resin solution was obtained. (1) Prepared as a resin solution 1 for a resin coating layer. After that, in a planetary motion type mixer (Nautamixer VN type manufactured by Hosokawa Micron Co., Ltd.) maintained at a temperature of 60 ° C., the amount of resin solid content becomes 1.0 part with respect to 100.0 parts of the magnetic carrier core 1. The resin liquid 1 for the first resin coating layer was charged, and the solvent was removed and the coating operation was performed for 40 minutes.
Then, the magnetic carrier coated with the first resin coating layer is transferred to a mixer (drum mixer UD-AT type manufactured by Sugiyama Heavy Industries, Ltd.) having spiral blades in a rotatable mixing container, and the mixing container is moved to 10 per minute. The mixture was rotated and stirred, and heat-treated in a nitrogen atmosphere at a temperature of 180 ° C. for 2 hours.

<Formation of second resin coating layer>
The coating resin C-1 solution was diluted with toluene so that the resin component was 5%, and a sufficiently stirred resin solution was prepared as the resin solution 1 for the second resin coating layer.
The resin liquid 1 for the second resin coating layer having a resin solid content of 1.5 parts and 100.0 parts of the magnetic carrier particles having the first resin coating layer obtained above are maintained at a temperature of 60 ° C. It was put into the planetary motion type mixer, and the solvent was removed and the coating operation was performed for 40 minutes.
Then, the magnetic carrier coated with the second resin coating layer is transferred to a mixer having spiral blades in a rotatable mixing container, and the mixing container is rotated 10 times per minute to stir, and the temperature is 120 under a nitrogen atmosphere. Heat treated at ° C. for 2 hours.

The obtained magnetic carrier was separated into low magnetic force products by magnetic force beneficiation, passed through a sieve having an opening of 150 μm, and then classified by a wind power classifier to obtain a magnetic carrier 1. Table 7 shows the physical characteristics of the magnetic carrier 1.

<Manufacturing example of magnetic carriers 2 to 18>
The composition of the resin liquid for the first resin coating layer was changed as shown in Table 5, the composition of the resin liquid for the second resin coating layer was changed as shown in Table 6, and the resin liquid for the first resin coating layer was changed. The magnetic carriers 2 to 18 were obtained in the same manner as in the production example of the magnetic carrier 1 except that the number of copies of the resin liquid for the second resin coating layer was changed as shown in Table 7. Regarding the resin liquid 6 for the first resin coating layer, 5 parts of adipic acid hydrazide (ADH) was added to the total amount of the coating resin A-6 solution obtained above for the first resin coating layer. The resin solution was 6.
The physical characteristics of the magnetic carriers 2 to 18 are shown in Table 7.

※ ３−アミノプロピルトリメトキシシラン

* 3-Aminopropyltrimethoxysilane

<Manufacturing example of cyan toner>
The materials shown in Table 8 were mixed well with a Henschel mixer (FM-75J type, manufactured by Nippon Coke Industries Co., Ltd.) and then set to a temperature of 130 ° C. Kneaded with a feed amount of 10 kg / hr (manufactured by Co., Ltd.) (the temperature of the kneaded product at the time of discharge was 150 ° C.). The obtained kneaded product was cooled, coarsely crushed with a hammer mill, and then finely pulverized with a mechanical crusher (trade name: T-250, manufactured by Turbo Industries, Ltd.) at a feed amount of 10 kg / hr. Then, particles having a weight average particle diameter of 4.8 μm were obtained.
The monomer composition of the polyester resin is as follows.
(Composition: 40 parts of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 10 parts of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane , 40 parts of terephthalic acid, 2 parts of trimellitic anhydride, 8 parts of fumaric acid))
The obtained particles were classified by a rotary classifier (trade name: TTSP100, manufactured by Hosokawa Micron Co., Ltd.) to cut fine powder and coarse powder. Cyan has a weight average particle size of 5.0 μm, an abundance rate of particles having a particle size of 3.0 μm or less is 18.8% by volume, and an abundance rate of particles having a particle size of 10.0 μm or more is 0.3% by volume. Toner particles were obtained.
Furthermore, the following materials were put into a Henshell mixer (trade name: FM-75J type, manufactured by Nippon Coke Industries Co., Ltd.), the peripheral speed of the rotating blades was set to 35.0 (m / sec), and the mixture was mixed in a mixing time of 3 minutes. By doing so, silica particles and titanium oxide particles were adhered to the surface of the cyan toner particles to obtain cyan toner.

-Cyan toner particles: 100.0 parts-Silica particles: 3.0 parts (Silica particles prepared by the fumed method were surface-treated with 1.5% by mass of hexamethyldisilazane, and then adjusted to a desired particle size distribution by classification. thing)
-Titanium oxide particles: 1.7 parts (anatase-type crystalline metatitanium acid surface-treated with an octylsilane compound)
-Strontium titanate particles: 0.5 part (surface treated with octylsilane compound)
Using the above cyan toner and magnetic carriers 1 to 18, each material is shaken with a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) so that the toner concentration becomes 7.0% by mass. 300 g of a two-component developer was prepared. The amplitude condition of the shaker was 200 rpm for 2 minutes.
On the other hand, 90 parts of the above cyan toner was added to 10 parts of the magnetic carriers 1 to 18 and mixed in an environment of room temperature and humidity of 23 ° C./50% RH for 5 minutes with a V-type mixer to prepare a replenishing developer. Obtained.

<Examples 1 to 13 and Comparative Examples 1 to 5>
The following evaluation was performed using the above two-component developer and the supplementary developer.
As an image forming apparatus, a Canon color copier imagePRESS C850 modified machine was used.
A two-component developer was placed in a cyan developer, a replenisher developer container containing a cyan replenisher was set, an image was formed, and various evaluations were performed before and after the durability test.
The test environment is a room temperature and low humidity environment (temperature 23 ° C./humidity 5RH%, hereinafter also referred to as “N / L”) and a high temperature and high humidity environment (temperature 30 ° C./humidity 80RH%, hereinafter also referred to as “H / H”). Adopted.
When the durability was examined, a chart of FFH output with an image ratio of 5% was used.
FFH is a value obtained by displaying 256 gradations in hexadecimal, 00h is the first gradation of 256 gradations (white background portion), and FFH is the 256th gradation of 256 gradations (solid portion). ..
(conditions)
Paper: Laser Beam Printer Paper CS-814 (81.4g / m ² ) (Canon Marketing Japan Inc.)
Image formation speed: A4 size, full color 85 sheets / min
Development conditions: The development contrast can be adjusted by any value, and it has been modified so that the automatic correction by the main unit does not work. The voltage (Vpp) between the peaks of the alternating electric field was modified so that the frequency could be changed from 0.7 kV to 1.8 kV in 0.1 kV increments at a frequency of 2.0 kHz.

Each evaluation item is shown below.
(1) Halftone density reproducibility (evaluation X concentration stability (N / L → H / H))
Evaluation was made using cyan toner.
The development contrast was adjusted in the main body of the copying machine left in the N / L environment for 72 hours, and an image in which each pattern was set to the density shown below was output. After that, the copying machine main body was left in an H / H environment for 3 hours with the development contrast set at N / L, and an image similar to N / L was output. The reflection density was determined from the deviation of the density of each pattern of the pattern image output in the H / H environment using a spectroscopic densitometer 500 series (manufactured by X-Rite).
Pattern 1: 0.10 to 0.14
Pattern 2: 0.25 to 0.29
Pattern 3: 0.45-0.49
Pattern 4: 0.65-0.69
Pattern 5: 0.85-0.89
Pattern 6: 1.05 to 1.09
Pattern 7: 1.25 to 1.29
Pattern 8: 1.48 to 1.52
The judgment criteria are as follows.
A (10 points): All pattern images satisfy the above density range B (9 points): One pattern image deviates from the above density range C (8 points): Two pattern images satisfy the above density range D (7 points): Three pattern images deviate from the above density range E (6 points): Four pattern images deviate from the above density range F (5 points): Five pattern images deviate from the above density range Out of range G (4 points): 6 pattern images out of the above density range H (3 points): 7 or more pattern images out of the above density range

(2) Halftone density reproducibility (evaluation Y concentration stability (H / H → N / L))
Evaluation was made using cyan toner.
The development contrast was adjusted in the main body of the copying machine left in the H / H environment for 72 hours, and an image in which each pattern was set to the density shown below was output. After that, the copying machine main body was left in an N / L environment for 3 hours with the development contrast set in H / H, and an image similar to that in H / H was output. The reflection density was determined from the deviation of the density of each pattern of the pattern image output in the N / L environment using a spectroscopic densitometer 500 series (manufactured by X-Rite).
Pattern 1: 0.10 to 0.14
Pattern 2: 0.25 to 0.29
Pattern 3: 0.45-0.49
Pattern 4: 0.65-0.69
Pattern 5: 0.85-0.89
Pattern 6: 1.05 to 1.09
Pattern 7: 1.25 to 1.29
Pattern 8: 1.48 to 1.52
The judgment criteria are as follows.
A (10 points): All pattern images satisfy the above density range B (9 points): One pattern image deviates from the above density range C (8 points): Two pattern images satisfy the above density range D (7 points): Three pattern images deviate from the above density range E (6 points): Four pattern images deviate from the above density range F (5 points): Five pattern images deviate from the above density range Out of range G (4 points): 6 pattern images out of the above density range H (3 points): 7 or more pattern images out of the above density range

(3) White spots (evaluation Z developability)
Under the N / L environment, the durability of 20000 sheets was evaluated using the chart of FFH output with an image ratio of 5%. Immediately after that, a chart was output in which halftone horizontal bands (30H width 10 mm) and solid black horizontal bands (FFH width 10 mm) were alternately arranged in the transfer direction of the transfer paper. The image was read by a scanner and binarized. The brightness distribution (256 gradations) of a certain line in the transport direction of the binarized image was taken. A tangent line is drawn on the brightness of the halftone at that time, and the area of brightness deviated from the tangent line at the rear end of the halftone part (area: sum of the number of brightness numbers) until it intersects with the solid part brightness is defined as the degree of whiteout, and is defined as the following standard. Evaluated based on. The evaluation was performed with a single cyan color.
A (10 points): 19 or less B (9 points): 20 or more and 24 or less C (8 points): 25 or more 29 or less D (7 points): 30 or more and 34 or less E (6 points): 35 or more and 39 or less F ( 5 points): 40 or more and 44 or less G (4 points): 45 or more and 49 or less H (3 points): 50 or more

1, 1K, 1Y, 1C, 1M: Electrostatic latent image carrier, 2, 2K, 2Y, 2C, 2M: Charger, 3, 3K, 3Y, 3C, 3M: Exposed device, 4, 4K, 4Y, 4C 4, 4M: developer, 5: developing container, 6, 6K, 6Y, 6C, 6M: developer carrier, 7: magnet, 8: regulatory member, 9: intermediate transfer body, 10K, 10Y, 10C, 10M: intermediate Transfer Charger, 11: Transfer Charger, 12: Transfer Material (Recording Medium), 13: Fixer, 14: Intermediate Transfer Cleaner, 15, 15K, 15Y, 15C, 15M: Cleaner, 16: Pre-Exposure, 17: Second resin coating layer, 18: First resin coating layer, 19: Magnetic carrier core, 20: Magnetic carrier surface, d: Layer thickness of resin coating layer, 21: Nitrogen atom derived from quaternary ammonium salt

Claims (11)

A magnetic carrier having a magnetic carrier core and a resin coating layer formed on the surface of the magnetic carrier core.
The resin coating layer is
A first resin coating layer containing a polymer having a structure represented by the following formula (1),
It has a second resin coating layer containing a vinyl resin formed on the surface of the first resin coating layer.
In the measurement by X-ray photoelectron spectroscopy for the magnetic carrier,
The ratio N1 of the number of nitrogen atoms derived from the quaternary ammonium salt on the surface of the magnetic carrier is 0.5 atomic% or less.
When the layer thickness of the resin coating layer is d (μm), it is derived from a quaternary ammonium salt at a position of 0.95 × d (μm) from the surface of the magnetic carrier to the magnetic carrier core in the depth direction. A magnetic carrier characterized in that the ratio N2 of the number of nitrogen atoms is 1.0 atomic% or more and 10.0 atomic% or less.

(In the formula (1), R ¹ to ³ independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁴ represents an alkylene group having 1 to 20 carbon atoms, and R ⁵ represents hydrogen. Represents an atom or a methyl group, where X ⁻ represents an anion.) The magnetic carrier according to claim 1, wherein the vinyl resin contained in the second resin coating layer has a structure represented by the following formula (2).

(In the formula (2), R ⁶ represents H or CH ₃ , and Y is a hydrocarbon group having a cyclic structure having 4 to 12 carbon atoms.) The magnetic carrier according to claim 2, wherein the vinyl-based resin contained in the second resin coating layer has a structure represented by the above formula (2) and a structure represented by the following formula (8).

(In formula (8), R ¹⁵ represents H or CH _3. M'is a divalent functional group having a polymer as a main chain, and the polymer is methyl acrylate, methyl methacrylate, Butyl acrylate (at least one selected from the group consisting of n-butyl, sec-butyl, iso-butyl and tert-butyl), butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, acrylonitrile, And a polymer of at least one monomer selected from the group consisting of methacrylonitrile.) The magnetic carrier according to any one of claims 1 to 3, wherein the polymer having the structure represented by the formula (1) further has a structure represented by the following formula (3).

(In the formula (3), R ⁷ represents H or CH ₃ , and Z is H or a hydrocarbon group having 1 to 20 carbon atoms.) Any of claims 1 to 4, wherein the polymer having the structure represented by the formula (1) further has at least one structure selected from the group consisting of the structures represented by the following formulas (4) to (6). The magnetic carrier according to item 1.

(In formula (4), R ⁸ and R ⁹ are each independently a hydrocarbon group having 1 to 20 carbon atoms.)

(In formula (5), R ¹⁰ and R ¹¹ are each independently a hydrocarbon group having 1 to 20 carbon atoms.)

(In formula (6), R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 20 carbon atoms.) The magnetic carrier according to any one of claims 1 to 5, wherein the polymer having the structure represented by the formula (1) further has a structure represented by the following formula (7).

(In formula (7), R ¹⁴ is a hydrocarbon group having 1 to 20 carbon atoms.) The magnetic carrier according to any one of claims 1 to 6, wherein the layer thickness d of the resin coating layer is 0.5 μm or more and 6.0 μm or less. A two-component developer containing a toner having toner particles containing a binder resin and a magnetic carrier.
A two-component developer, wherein the magnetic carrier is the magnetic carrier according to any one of claims 1 to 7. Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing step of developing the electrostatic latent image with a two-component developer to form a toner image.
An image forming method comprising a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
An image forming method, wherein the two-component developer is the two-component developer according to claim 8. Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing process in which the electrostatic latent image is developed using a two-component developer in a developing device to form a toner image.
It has a transfer step of transferring the toner image to the transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
A replenishing developer for use in an image forming method in which a replenishing developer is replenished to the developing device in response to a decrease in the toner concentration of the two-component developing agent in the developing device.
The replenishing developer contains a magnetic carrier and a toner having toner particles containing a binder resin.
The replenishing developer contains 2 parts by mass or more and 50 parts by mass or less of the toner with respect to 1 part by mass of the magnetic carrier.
The replenishing developer, wherein the magnetic carrier is the magnetic carrier according to any one of claims 1 to 7. Charging process for charging the electrostatic latent image carrier,
An electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier,
A developing process in which the electrostatic latent image is developed using a two-component developer in a developing device to form a toner image.
It has a transfer step of transferring the toner image to the transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image to the transfer material.
An image forming method in which a replenishing developer is replenished to the developing device according to a decrease in the toner concentration of the two-component developing agent in the developing device.
The image forming method, wherein the replenishing developer is the replenishing developing agent according to claim 10.

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