JP2022070703A - Two-component developer, developer for replenishment, and image forming method - Google Patents

Abstract

To provide a two-component developer that has satisfactory followability to an environmental change and durability, and even in an environment in which the developer is used at high temperature and high humidity and then left to stand and subsequently printing is performed at normal temperature and low humidity, can prevent a variation in hue and stably obtain a high-definition image.SOLUTION: A two-component developer includes toner and magnetic carrier. The toner is a toner having a toner particle, and silica fine particles A present on the surface of the toner particle. The number average particle diameter of primary particles of the silica fine particles A is 80 nm or more and 200 nm or less. After 1800 seconds from when the silica fine particles A are electrified in an environment of a temperature of 23°C and a relative humidity of 50%, the silica fine particles A have a charge attenuation constant α of 0.0005 or more and 0.0100 or less. The magnetic carrier is a magnetic carrier having a magnetic carrier particle having a resin coating layer. The resin coating layer contains a resin including a constitutional unit derived from a (meth)acrylate compound. The resin coating layer contains a phosphorus element or a sulfur element.SELECTED DRAWING: None

Description

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

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 attached to the electrostatic latent image to form the electrostatic latent image. The method of developing is generally used. 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 charge is applied to the toner, and the charge is developed as a driving force. It has been adopted.

Since the two-component developing method can impart functions such as stirring, transporting, and charging of the developer to the magnetic carrier, the division of functions with the toner is clear, and therefore, the controllability of the developer performance is good. There is.

On the other hand, in recent years, due to technological advances 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 devices. In order to meet such demands, it is required to improve the performance of the two-component developer.

As a magnetic carrier for achieving such a two-component developer, a magnetic carrier that provides a two-component developer having a high charge amount, suppressing fluctuations in the charge amount due to environmental changes, and having excellent durability. Has been proposed (see Patent Document 1). This magnetic carrier is characterized by containing a phosphorus element in the coat layer of the magnetic carrier particles.

Japanese Unexamined Patent Publication No. 2017-203852

The magnetic carrier of Patent Document 1 has improved problems such as followability to environmental changes and durability.
However, there is an increasing demand in the market for suppressing color fluctuations during printing and stably obtaining high-definition images even in various environments. The two-component developer using the carrier of Patent Document 1 has no problem in a normal environment, but is accompanied by severe environmental changes such as printing under normal temperature and low humidity after being left at high temperature and high humidity. In some cases, there is a concern that color fluctuation may occur immediately after printing. Therefore, there is an urgent need to develop a two-component developer that can stably obtain high-definition images by suppressing color fluctuations during printing even in various environments.

An object of the present invention is to provide a two-component developer that solves such a problem. Specifically, it has the ability to follow the amount of charge required in environmental changes (hereinafter, also simply referred to as "following to environmental changes") and durability to long-term use (hereinafter, also simply referred to as "durability"). It is good. Furthermore, a two-component developer that suppresses color fluctuations and stably obtains high-definition images even under severe environmental changes such as printing at room temperature and low humidity after being left after use under high temperature and high humidity. To provide.

By using a two-component developer as shown below, the present inventors have good follow-up to environmental changes and durability, and for example, after using the product under high temperature and high humidity, the present inventors have left it for a long time. We have found that it is possible to stably obtain high-definition images by suppressing color fluctuations even in a harsh environment such as printing at room temperature and low humidity.

That is, the present invention is a two-component developer containing a toner and a magnetic carrier.
The toner is a toner having toner particles containing a binder resin and silica fine particles A present on the surface of the toner particles.
The silica fine particles A have an average number of primary particles of 80 nm or more and 200 nm or less.
The silica fine particles A have a charge attenuation constant α of 0.0005 or more and 0.0100 or less after 1800 seconds from being charged in an environment of a temperature of 23 ° C. and a relative humidity of 50%.
The magnetic carrier is a magnetic carrier having a magnetic carrier core and magnetic carrier particles having a resin coating layer formed on the surface of the magnetic carrier core.
The resin coating layer contains a resin containing a structural unit derived from a (meth) acrylic acid ester compound, and contains a resin.
The resin coating layer relates to a two-component developer characterized by containing a phosphorus element or a sulfur element.

Further, in the present invention, a replenishing developer is replenished to the developing device according to a decrease in the toner concentration of the two-component developer in the developing device, and an electrostatic latent image formed on the surface of the electrostatic latent image carrier is produced. A replenishing developer for use in a two-component developing method that develops using a two-component developer in the developer and discharges excess magnetic carriers inside the developer from the developer as needed. There,
The replenishing developer is a two-component developing agent according to the present invention, wherein the toner amount with respect to 1 part by mass of the magnetic carrier is 2 parts by mass or more and 50 parts by mass or less. Regarding.

Further, the present invention comprises a charging step of charging an 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, and the electrostatic latent image in a developing device. A developing step of developing with a two-component developer to form a toner image, a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer body, and a transfer material of the transferred toner image. The present invention relates to an image forming method having a fixing step of fixing to, wherein the two-component developer according to the present invention is used as the two-component developer.

According to the two-component developer of the present invention, it has good follow-up to environmental changes and durability, and is severe, for example, after being used in high temperature and high humidity and then left to print at normal temperature and low humidity. Even in the environment, it is possible to suppress color fluctuations and stably obtain high-definition images. Further, the effect can be similarly exhibited by the replenishing developer or the image forming method of the present invention.

It is a schematic diagram of an image forming apparatus. It is a schematic diagram of an image forming apparatus. It is a schematic diagram of the measuring device of the specific resistance of a magnetic carrier.

In the present invention, the description of "○○ or more and XX or less" and "○○ to XX" indicating a numerical range means a numerical range including a lower limit and an upper limit which are end points, unless otherwise specified.
In the present invention, the (meth) acrylic acid ester means an acrylic acid ester and / or a methacrylic acid ester.

The two-component developer of the present invention is a two-component developer containing a toner and a magnetic carrier.
The toner is a toner having toner particles containing a binder resin and silica fine particles A present on the surface of the toner particles.
The silica fine particles A have an average number of primary particles of 80 nm or more and 200 nm or less.
The silica fine particles A have a charge attenuation constant α of 0.0005 or more and 0.0100 or less after 1800 seconds from being charged in an environment of a temperature of 23 ° C. and a relative humidity of 50%.
The magnetic carrier is a magnetic carrier having a magnetic carrier core and magnetic carrier particles having a resin coating layer formed on the surface of the magnetic carrier core.
The resin coating layer contains a resin containing a structural unit derived from a (meth) acrylic acid ester compound, and contains a resin.
The resin coating layer is characterized by containing a phosphorus element or a sulfur element.

The present inventors have good follow-up to environmental changes and durability, and are accompanied by severe environmental changes such as printing under normal temperature and low humidity after being left at high temperature and high humidity for example. As a result of diligent studies for the purpose of suppressing color fluctuations and stably obtaining high-definition images, it was found that the combination of the magnetic carrier and the toner having the above configuration is important.

The mechanism by which the above-mentioned problems can be solved by the two-component developer of the present invention is considered as follows.
The magnetic carrier particles used in the two-component developer of the present invention have a resin coating layer containing a structural unit derived from a (meth) acrylic acid ester compound on the surface, and the coating resin layer contains a phosphorus element or a sulfur element. ing. By including the structural unit derived from the (meth) acrylic acid ester compound in the resin coating layer, the hydrophobicity of the magnetic carrier particles is improved, and the decrease in the amount of charge under high temperature and high humidity is suppressed. Further, since the resin coating layer containing such a structural unit has appropriate chargeability and mechanical strength, it is excellent in durability. Further, since the phosphorus element or the sulfur element has a positive charge property, the charge imparting property of the magnetic carrier is improved. Further, by containing silica fine particles having a certain charge-relaxing property on the surface of the toner particles, the silica fine particles themselves appropriately promote the transfer of the electric charge of the toner, and the charge rise of the two-component developer is accelerated. .. Therefore, even when printed in an environment where the amount of charge tends to be high, such as a room temperature and low humidity environment after being left in a high temperature and high humidity and the amount of charge decreases, it is easy to transfer the charge between the phosphorus element or sulfur element and the silica fine particles. It is done in. As a result, it is considered that the rise of charge of the two-component developer becomes good, the followability to environmental changes and durability are good, and a high-definition image in which color fluctuation is suppressed can be stably obtained. ..

From the viewpoint of suppressing color fluctuation, it is important that the number average particle size of the primary particles of the silica fine particles A is 80 nm or more and 200 nm or less. When the number average particle size of the primary particles of the silica fine particles A is less than 80 nm, there are many opportunities for the magnetic carrier and the base portion of the toner particles to come into contact with each other because the number average particle size of the primary particles is small, and the two-component development The charge distribution of the agent may be broad, and the tint tends to fluctuate. When the number average particle size of the primary particles is larger than 200 nm, the charge transfer time in the silica fine particles becomes long, so that the charge rise of the two-component developer is delayed and the color tone tends to fluctuate.

Further, from the same viewpoint, the silica fine particles A have a charge attenuation constant α of 0.0005 or more and 0.0100 or less after 1800 seconds from a charged state in an environment of a temperature of 23 ° C. and a relative humidity of 50%. is important. When the charge attenuation constant α is less than 0.0005, the rise of charge of the two-component developer is delayed, and the color tone is liable to fluctuate. If it is larger than 0.0100, the decrease in the charge amount after being left in high temperature and high humidity becomes large, so that the difference between the initial charge amount and the saturated charge amount in the subsequent printing under normal temperature and low humidity becomes large, and the color tone fluctuates. It will be easier to do.

The silica fine particles A used in the present invention are particles containing silica (that is, SiO ₂ ) as a main component, and can be produced by a known production method such as a combustion method, a melting method, or hydrothermal synthesis. Among them, silica fine particles A produced by the combustion method or the melting method are more suitable in order to further enhance the effect of suppressing charge relaxation in a high temperature and high humidity environment and from the viewpoint of high resistance and being less susceptible to humidity. preferable.

In the combustion method, siloxane gas is introduced into a burner together with a carrier gas such as nitrogen by vaporizing a siloxane compound, and silica fine particles are produced by diffusing and mixing with a combustion-supporting gas such as oxygen to burn the siloxane gas. The method. Another combustion method is a method in which silicon tetrachloride is burned at a high temperature together with a mixed gas of oxygen, hydrogen, for example, a diluting gas such as nitrogen to generate silica fine particles (fumed silica).

Further, the melting method is a method in which a slurry of metallic silicon fine particles is sprayed into a flame and sphericalized while undergoing an oxidation reaction to obtain silica particles.

In the present invention, a combustion method for producing silica fine particles by burning siloxane gas is given as a preferable example from the viewpoint of controllability of the number average particle size of the primary particles of the silica fine particles A.

Examples of the siloxane compound include hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane.

In the present invention, the silica fine particles A used in the present invention can be obtained by incorporating an iron atom, preferably an aluminum atom, into the silica fine particles A.
The amount of iron atoms contained in the silica fine particles A is preferably 20 ppm or more and 2000 ppm or less in terms of oxide, and more preferably 50 ppm or more and 1000 ppm or less. When the amount of iron atoms contained in the silica fine particles A is in this range, the color fluctuation can be suitably suppressed.
As a method of incorporating these metal atoms in the silica fine particles A, it is possible to adjust the purity of the siloxane compound and include them.

Further, it is preferable that the surface of the silica fine particles A is hydrophobized with a silane coupling agent, silicone oil or the like.
As the silane coupling agent, those surface-treated with hexamethyldisilazane (HMDS) are more preferable.
As the silicone oil, those surface-treated with dimethyl silicone oil are more preferable.

The method of surface treatment with a silane coupling agent is not particularly limited, and a known method can be used. For example, a method of spraying a vaporized silane coupling agent or contacting the silica fine particles A in the form of a cloud by stirring with steam is generally preferable.
The surface treatment with the above-mentioned silane coupling agent is preferably in the range of 1 part by weight or more and 80 parts by weight or less per 100 parts by weight of the silica fine particles A.

Further, from the viewpoint of followability to environmental changes and durability, it is important that the resin coating layer on the surface of the magnetic carrier core contains a structural unit derived from the (meth) acrylic acid ester compound. By including the structural unit derived from the (meth) acrylic acid ester compound in the resin coating layer, the hydrophobicity of the magnetic carrier particles is improved, and the decrease in the amount of charge under high temperature and high humidity is suppressed. Further, since the resin coating layer containing such a structural unit has appropriate chargeability and mechanical strength, the magnetic carrier is excellent in durability. The alicyclic (meth) acrylic acid ester compound is preferable as the (meth) acrylic acid ester compound from the viewpoint of further improving the followability and durability of the two-component developer to environmental changes. Further, from the viewpoint of improving the followability and durability to environmental changes, the alicyclic (meth) acrylic acid ester compound preferably has a cycloalkyl group having 5 or more and 8 or less carbon atoms, and among them, a cycloalkyl having 6 carbon atoms. It is preferably an alicyclic (meth) cyclohexyl acrylate having a group.

The resin coating layer may be obtained by copolymerizing an alicyclic (meth) acrylic acid ester compound with another monomer. Examples of the other monomer include a (meth) acrylic monomer such as a chain or branched (meth) acrylic acid ester and a (meth) acrylic acid aminoalkyl ester, and a single amount of vinyl such as styrene, vinyl acetate and vinyl chloride. The body etc. can be mentioned. Among them, it is preferable to contain a (meth) acrylic monomer, and more preferably to contain a structural unit derived from a chain-type (meth) acrylic acid ester compound.

The content of the structural unit derived from the alicyclic (meth) acrylic acid ester compound in the coated resin layer is preferably 10.0% by mass or more and 90.0% by mass or less, and 20% by mass or more and 80% by mass. % Or less is more preferable. Within the above range, the environmental stability and durability of the charge amount of the magnetic carrier are further improved. The content of the structural unit is substantially the same as the content of the alicyclic (meth) acrylic acid ester compound with respect to the total amount of monomers in the production of the resin.

From the viewpoint of improving the charge-imparting property of the magnetic carrier, it is important that the resin coating layer contains a phosphorus element or a sulfur element, and it is more preferable to contain a phosphorus element. The phosphorus element may be present in the resin coating layer as a part of the resin, or may be present in the coating resin layer as a compound containing the phosphorus element separately from the resin.

The phosphorus element is contained in the coating resin layer as a phosphoric acid such as phosphoric acid, phosphite, phosphinic acid, an organic phosphorus compound such as a phosphoric acid ester or a phosphite ester, or a component derived from these. It is preferable to have. In the phosphorus atom contained in such a component, the phosphorus atom-oxygen atom bond (P = O, PO) is polarized due to the difference in electronegativity, so that the resin coating layer is just large. Charged.

Of these, organic phosphorus compounds are more preferable, and phosphoric acid esters are even more preferable, from the viewpoint of imparting an appropriate amount of charge to the toner. Phosphoric acid esters include monoesters (P (= O) (OH) ₂ (OR)), diesters (P (= O) (OH) (OR) ₂ ), and triesters (P (= O) (OR) ₃ ). ) Can be used. In the above formula, R independently represents an arbitrary monovalent group other than a hydrogen atom, and may be the same or different. That is, in the magnetic carrier used in the two-component developer of the present invention, the resin coating layer contains a phosphoric acid group (-OP (= O) (OH) ₂ ) and an acidic phosphoric acid ester group (-OP (= O) (OH) 2). It is preferably contained as an OP (= O) (OH) (OR)) or a group of salts thereof, or a phosphate ester group (—OP (= O) (OR) ₂ ). In the above formula, R independently represents an arbitrary monovalent group other than a hydrogen atom, and may be the same or different.

The presence of the above group in the resin coating layer can be confirmed by using a known mass spectrometric means such as TOF-MS or LC-MS.

The phosphorus element content of the resin coating layer is 0.0005 or more and 0 as the "ratio (P / C) between the phosphorus element content (P) and the carbon element content (C)" calculated from the measurement method described later. It is preferably 0200 or less. If it is 0.0005 or more, the decrease in the amount of charge is suppressed under high temperature and high humidity. On the other hand, if it is 0.0200 or less, overcharging is suppressed under low temperature and low humidity. Further, from the viewpoint of achieving both environmental stability and durability of the charge amount at a good level, it is more preferably 0.0010 or more and 0.0150 or less, and particularly preferably 0.0010 or more and 0.0100 or less. .. The P / C can be controlled by adjusting the amount of the compound containing the phosphorus element and the like as described later.

The method for introducing the phosphorus element into the resin coating layer is not particularly limited, but a method of adding a compound containing the phosphorus element at the stage of producing the resin is preferable. For example, a method for producing the resin using a compound containing a phosphorus element as a surfactant or a monomer can be mentioned.

As one of the methods for introducing the phosphorus element into the resin coating layer, it is preferable to produce the resin by an emulsion polymerization method using a surfactant containing the phosphorus element. The preferred reason is inferred as follows. In the resin particles produced by this method, the phosphorus element is oriented on the outside of the resin particles. That is, the resin particles have a structure in which the inside is hydrophobic, but the surface easily adsorbs water. A magnetic carrier produced using these resin particles can achieve both a reduction in water adsorption under high temperature and high humidity and an improvement in water retention under low temperature and low humidity. Therefore, the decrease in the amount of charge under high temperature and high humidity is suppressed, while the overcharge under low temperature and low humidity is suppressed. It is considered that the magnetic carrier according to the present invention can impart a constant charge amount to the toner even if the temperature / humidity environment changes.

In this method, the P / C can be controlled within a desired range by appropriately adjusting the amount of the surfactant containing a phosphorus element, the cleaning conditions of the produced resin, and the like. Examples of the resin cleaning method include a method of repeating filtration of the resin and redispersion in ion-exchanged water or an ion-exchanged water / alcohol mixed solvent. Further, the surfactant containing a phosphorus element may be further added after the resin is manufactured.
As the surfactant containing a phosphorus element, a phosphoric acid ester type surfactant such as an alkyl phosphate ester or a salt thereof, a polyoxyethylene alkyl ether phosphoric acid ester or a salt thereof is preferable. By using such a surfactant, the phosphorus element is localized on the surface of the resin particles, so that a carrier having excellent charge-imparting property can be obtained.

The alkyl phosphate ester is a compound represented by P (= O) (OH) _3-n (OR) _n , in which R is an alkyl group having 4 or more carbon atoms and 30 or less carbon atoms, and n is 1. Or 2. Specific examples thereof include lauryl phosphate, tridecyl phosphate, myristyl phosphate, stearyl phosphate, oleyl phosphate and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.

The polyoxyethylene alkyl ether phosphate ester is a compound represented by [RO (CH ₂ CH ₂ O) _m ] _n P (= O) (OH) _3-n , and in the formula, R has 4 carbon atoms. It is an alkyl group of 30 or more, n is 1 or 2, and m is 1 or more and 50 or less. Specific examples thereof include polyoxyethylene tridecyl ether phosphoric acid ester and polyoxyethylene lauryl ether phosphoric acid ester. Above all, from the viewpoint of resin manufacturability, polyoxyethylene tridecyl ether phosphoric acid ester is preferable. These may be used individually by 1 type, or may be used in combination of 2 or more type.

The amount of the surfactant containing the phosphorus element to be used is preferably 0.1% by mass or more and 1.5% by mass or less, preferably 0.2% by mass, based on the total amount of the monomers for forming the resin. It is more preferably 1.0% by mass or less, and even more preferably 0.3% by mass or more and 0.5% by mass or less.

As one of the methods for introducing the phosphorus element into the resin coating layer, it is also preferable to copolymerize the phosphoric element-containing monomer with the above-mentioned alicyclic (meth) acrylic acid ester compound to produce a resin.

In this method, the P / C can be controlled within a desired range by appropriately adjusting the copolymerization ratio of the monomer containing a phosphorus element and the monomer other than that.

Examples of the monomer containing a phosphorus element include 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.

As another method for introducing the phosphorus element into the resin coating layer, for example, the above resin may be produced by using a polymerization initiator containing the phosphorus element. In the case of this method, the P / C can be controlled within a desired range by appropriately adjusting the amount of the polymerization initiator used.

<Toner>
As the toner of the present invention, a polyester resin is preferably used as a binder resin for the toner particles. Examples of the polyester resin include an amorphous polyester resin and a crystalline polyester resin.

When a crystalline polyester resin is used, it is 3.0 parts by mass or more and 15.0 parts by mass or less, and 4.0 parts by mass or more and 12.0 parts by mass or less with respect to 100.0 parts by mass of the non-crystalline polyester resin. Is preferable.

In the present invention, the crystalline polyester resin is a resin in which a heat absorption peak is observed in differential scanning calorimetry (DSC).

The crystalline polyester resin can be obtained by reacting a polyvalent carboxylic acid having a divalent value or higher with a diol. Among them, a resin obtained by polycondensing an aliphatic diol and an aliphatic dicarboxylic acid is preferable because of its high crystallinity. Further, in the present invention, only one kind of crystalline polyester resin may be used, or a plurality of kinds may be used in combination.

In the present invention, the crystalline polyester resin contains an alcohol component containing at least one compound selected from the group consisting of aliphatic diols having 2 or more and 22 or less carbon atoms and derivatives thereof, and the crystalline polyester resin having 2 or more and 22 or less carbon atoms. It is preferable that the resin is obtained by depolymerizing a carboxylic acid component containing at least one compound selected from the group consisting of aliphatic dicarboxylic acids and derivatives thereof.

Among them, the crystalline polyester resin has an alcohol component containing at least one compound selected from the group consisting of aliphatic diols having 6 or more and 12 or less carbon atoms and derivatives thereof, and 6 or more and 12 or less carbon atoms. A crystalline polyester resin obtained by depolymerizing a carboxylic acid component containing at least one compound selected from the group consisting of aliphatic dicarboxylic acids and derivatives thereof is a change in followability to environmental changes. It is more preferable not only from the viewpoint of durability but also from the viewpoint of low temperature fixing property and blocking resistance.

The aliphatic diol having 2 or more and 22 or less carbon atoms (preferably 6 or more and 12 or less carbon atoms) is not particularly limited, but may be a chain-like (preferably linear) aliphatic diol.

For example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-butadiene glycol, 1,5-pentanediol, Neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanezil, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12 -Dodecanediol can be mentioned.

Among these, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12 -Linear aliphatic α, ω-diol such as dodecanediol is preferably exemplified.

In the present invention, the derivative is not particularly limited as long as the same resin structure can be obtained by the above polycondensation. For example, a derivative obtained by esterifying the above diol can be mentioned.

In the present invention, at least one selected from the group consisting of the above-mentioned aliphatic diols having 2 or more and 22 or less carbon atoms (preferably 6 or more and 12 or less carbon atoms) and derivatives thereof in the alcohol component constituting the crystalline polyester resin. The compound of the above is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total alcohol component.

In the present invention, polyhydric alcohols other than the above aliphatic diols can also be used.
Among the polyhydric alcohols, examples of diols other than the aliphatic diol include aromatic alcohols such as polyoxyethylene glycol A and polyoxypropylene glycol A; 1,4-cyclohexanedimethanol and the like.
Among the polyhydric alcohols, the trihydric or higher polyhydric alcohols include aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4. -Butantriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and aliphatic alcohols such as trimethylolpropane. Be done.

Further, in the present invention, a monohydric alcohol may be used to the extent that the characteristics of the crystalline polyester resin are not impaired. Examples of the monohydric alcohol include n-butanol, isobutanol, sec-butanol, n-hexanol, n-octanol, 2-ethylhexanol, cyclohexanol, and benzyl alcohol.

On the other hand, the aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms (preferably 6 or more and 12 or less carbon atoms) is not particularly limited, but may be a chain (preferably linear) aliphatic dicarboxylic acid. ..
For example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, glutaconic acid, azelaic acid, sebacic acid, nonandicarboxylic acid, decandicarboxylic acid, undecandicarboxylic acid, dodecandicarboxylic acid, maleic acid. , Fumaric acid, mesaconic acid, citraconic acid, itaconic acid and the like.
Hydrolyzed acid anhydrides or lower alkyl esters are also included.

In the present invention, the derivative is not particularly limited as long as the same resin structure can be obtained by the above polycondensation. For example, an acid anhydride of the dicarboxylic acid component, a derivative obtained by methyl esterifying, ethyl esterifying, or acid chlorideizing the dicarboxylic acid component can be mentioned.

In the present invention, in the carboxylic acid component constituting the crystalline polyester resin, at least selected from the group consisting of the above-mentioned aliphatic dicarboxylic acids having 2 or more and 22 or less carbon atoms (preferably 6 or more and 12 or less carbon atoms) and derivatives thereof. The amount of one compound is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total carboxylic acid component.

In the present invention, polyvalent carboxylic acids other than the above aliphatic dicarboxylic acids can also be used. Among the polyvalent carboxylic acids, the divalent carboxylic acid other than the aliphatic dicarboxylic acid is an aromatic carboxylic acid such as isophthalic acid and terephthalic acid; an aliphatic carboxylic acid such as n-dodecylsuccinic acid and n-dodecenylsuccinic acid. Acids; Examples include alicyclic carboxylic acids such as cyclohexanedicarboxylic acids, and these acid anhydrides or lower alkyl esters are also included.

Among other polyvalent carboxylic acids, the trivalent or higher polyvalent carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimeritic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2, Aromatic carboxylic acids such as 4-naphthalentricarboxylic acid and pyromellitic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2- Examples thereof include aliphatic carboxylic acids such as methylenecarboxypropane, and derivatives such as acid anhydrides or lower alkyl esters thereof are also included.

Further, in the present invention, a monovalent carboxylic acid may be used to the extent that the characteristics of the crystalline polyester resin are not impaired. Examples of the monovalent carboxylic acid include benzoic acid, naphthalenecarboxylic acid, salicylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, phenoxyacetic acid, biphenylcarboxylic acid, acetic acid, propionic acid, butyric acid and octanoic acid. ..

In the present invention, the crystalline polyester resin can be produced according to a usual polyester synthesis method. For example, a crystalline polyester resin can be obtained by subjecting the carboxylic acid component and the alcohol component to an esterification reaction or a transesterification reaction, and then subjecting them to a shrink polymerization reaction under reduced pressure or by introducing nitrogen gas according to a conventional method. ..

The esterification or transesterification reaction may be carried out using a conventional esterification catalyst or transesterification catalyst such as sulfuric acid, titanium butoxide, tin 2-ethylhexanoate, dibutyltin oxide, manganese acetate, and magnesium acetate, if necessary. It can be carried out.

Further, the above-mentioned polymerization reaction is carried out by a known polymerization catalyst such as a conventional polymerization catalyst such as titanium butoxide, tin 2-ethylhexanoate, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, and germanium dioxide. Can be done using. The polymerization temperature and the amount of catalyst are not particularly limited and may be appropriately determined.

In the esterification or transesterification reaction, or polycondensation reaction, all the monomers are charged in a batch to increase the strength of the obtained crystalline polyester resin, or the divalent monomer is first reacted to reduce the low molecular weight component. After that, a method such as adding a monomer having a valence of 3 or more and causing the reaction may be used.

The non-crystalline polyester resin can be produced according to a usual polyester synthesis method, like the crystalline polyester resin.

The monomers used in the production of the amorphous polyester resin include polyhydric alcohol (dihydric or trihydric or higher alcohol), polyvalent carboxylic acid (divalent or trivalent or higher carboxylic acid), and their acid anhydrides. Or their lower alkyl esters.

Here, when producing a branched polymer, it is effective to partially crosslink the amorphous polyester resin in the molecule, and for that purpose, it is preferable to use a polyfunctional compound having a valence of 3 or more. That is, it is preferable to include a trivalent or higher carboxylic acid and its acid anhydride or a lower alkyl ester thereof, and / or a trivalent or higher alcohol as the monomer.

Examples of the polyhydric alcohol and the polyvalent carboxylic acid used in the production of the amorphous polyester resin include the following.

（式（Ａ）中、Ｒはエチレン又はプロピレン基であり、ｘ及びｙはそれぞれ０以上の整数であり、かつ、ｘ＋ｙの平均値は０以上１０以下である。）

（式（Ｂ）中、Ｒ’は－ＣＨ_２ＣＨ_２－、－ＣＨ_２－ＣＨ（ＣＨ_３）－又は－ＣＨ_２－Ｃ（ＣＨ_３）_２－を示し、ｘ’、ｙ’は０以上の整数であり、且つ、ｘ’＋ｙ’の平均値は０以上１０以下である。） Examples of the divalent alcohol include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, and 1,6. -Hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydride bisphenol A, bisphenol represented by the following formula (A) and its derivatives; and diols represented by the following formula (B). ..

(In the formula (A), R is an ethylene or propylene group, x and y are integers of 0 or more, respectively, and the average value of x + y is 0 or more and 10 or less.)

(In the formula (B), R'indicates -CH ₂ CH _2- , -CH ₂ -CH (CH ₃ )-or -CH ₂ -C (CH ₃ ) _2- , and x', y'is 0 or more. And the average value of x'+ y'is 0 or more and 10 or less.)

Examples of the divalent carboxylic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebatic acid, azelaic acid, malonic acid and n. -Dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid, and isooctyl succinic acid. Moreover, you may use these acid anhydrides and lower alkyl esters.
Of these, maleic acid, fumaric acid, terephthalic acid, adipic acid, and n-dodecenyl succinic acid are preferably used.

Examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, and the like. 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene Can be mentioned.
Of these, glycerol, trimethylolpropane, and pentaerythritol can be preferably exemplified.

The trivalent or higher carboxylic acid is, for example, 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalentricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7, Examples include 8-octanetetracarboxylic acid, pyromellitic acid and empol trimer acid. Moreover, you may use these acid anhydrides and lower alkyl esters.
Of these, 1,2,4-benzenetricarboxylic acid (trimellitic acid) or its derivative is preferably used because it is inexpensive and reaction control is easy.

The above divalent alcohol and trihydric or higher alcohol can be used alone or in combination of two or more. Similarly, the divalent carboxylic acid and the like and the trivalent or higher carboxylic acid can be used alone or in combination of two or more.

In the present invention, in the molecular weight distribution measured by gel permeation chromatography (GPC) of a tetrahydrofuran (THF) soluble component of an amorphous polyester resin, the peak molecular weight of 4000 or more and 13000 or less is the followability of environmental changes. And is preferable from the viewpoint of durability. Further, satisfying the above range is preferable from the viewpoint of low temperature fixing property and hot offset resistance.

The acid value of the amorphous polyester resin is preferably 2 mgKOH / g or more and 30 mgKOH / g or less from the viewpoint of chargeability in a high temperature and high humidity environment.

Further, the hydroxyl value of the amorphous polyester resin is preferably 2 mgKOH / g or more and 20 mgKOH / g or less from the viewpoint of low temperature fixability and blocking resistance.
In the present invention, the amorphous polyester resin contains a low molecular weight amorphous polyester resin having a peak molecular weight of 4500 or more and 7000 or less, and a high molecular weight amorphous polyester resin having a peak molecular weight of 8500 or more and 9500 or less. Aspects to be used are also preferable.

In this case, the mixing ratio (B / C) of the high molecular weight amorphous polyester resin and the low molecular weight amorphous polyester resin is 10/90 or more and 60/40 or less on a mass basis, which follows the environmental change. It is preferable not only from the viewpoint of change in properties and durability but also from the viewpoint of low temperature fixing property and hot offset resistance.

It is preferable that the peak molecular weight of the high molecular weight amorphous polyester resin is 8500 or more and 9500 or less from the viewpoint of not only the change in followability to environmental changes and durability but also the hot offset resistance. The acid value of the high molecular weight amorphous polyester resin is preferably 10 mgKOH / g or more and 30 mgKOH / g or less from the viewpoint of chargeability in a high temperature and high humidity environment.

The peak molecular weight of the low molecular weight amorphous polyester resin is preferably 4500 or more and 7000 or less from the viewpoint of not only the change in followability to environmental changes and durability but also the low temperature fixability. The acid value of the low molecular weight amorphous polyester resin is preferably 10 mgKOH / g or less from the viewpoint of chargeability in a high temperature and high humidity environment.

The acid value is the number of mg of potassium hydroxide required to neutralize the acid contained in 1 g of the sample. The acid value of the resin is measured according to JIS K0070-1992. The hydroxyl value is the number of mg of potassium hydroxide required to neutralize acetic acid bonded to the hydroxyl group when acetylating 1 g of the sample. The hydroxyl value of the amorphous polyester is measured according to JIS K0070-1992.

In the present invention, the toner particles may contain wax. Examples of the wax include the following.

Hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymers, microcrystallin wax, paraffin wax, and Fishertropsh wax; oxides of hydrocarbon waxes such as polyethylene oxide wax or blocks thereof. Polymers; waxes containing fatty acid esters such as carnauba wax as the main component; deoxidized fatty acid esters such as carnauba wax partially or wholly deoxidized.

In addition, the following can be mentioned. Saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brushzic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubil alcohol, Saturated alcohols such as ceryl alcohol and melisyl alcohol; polyhydric alcohols such as sorbitol; fatty acids such as palmitic acid, stearic acid, behenic acid, and montanic acid, and stearyl alcohol, aralkyl alcohol, behenyl alcohol, Esters with alcohols such as carnaubil alcohol, ceryl alcohol, and mericyl alcohol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylene bisstearic acid amide, ethylene biscaprin Saturated fatty acid bisamides such as acid amides, ethylene bislauric acid amides, and hexamethylene bisstearic acid amides; ethylene bisoleic acid amides, hexamethylene bisoleic acid amides, N, N-diorail adipic acid amides, and N, Unsaturated fatty acid amides such as N-diorail sebasic acid amide; m-xylene bisstearic acid amides and aromatic bisamides such as N, N-distearylisophthalic acid amides; calcium stearate, calcium laurate, stearer. Fatty acid metal salts such as zinc acid and magnesium stearate (generally referred to as metal soap); fatty acid hydrocarbon wax grafted with vinyl monomers such as styrene and acrylic acid. Class; Partial esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; Methyl ester compounds having a hydroxy group obtained by hydrogenation of vegetable fats and oils.

Among these waxes, hydrocarbon waxes such as low molecular weight polypropylene, paraffin wax, and Fisher Tropsch wax, or fatty acid esters such as carnauba wax, from the viewpoint of improving low temperature fixability and hot offset resistance. A wax system is preferable. In the present invention, the hydrocarbon wax is more preferable in that the hot offset resistance is further improved.

In the present invention, the wax content is preferably 1.0 part by mass or more and 20.0 parts by mass or less, and 3.0 parts by mass or more and 15.0 parts by mass with respect to 100.0 parts by mass of the binder resin. More preferably, it is less than or equal to a part.

The peak temperature of the maximum endothermic peak measured using a differential scanning calorimetry (DSC) for wax is preferably 45 ° C. or higher and 140 ° C. or lower, and more preferably 70 ° C. or higher and 100 ° C. or lower. When the peak temperature of the maximum endothermic peak of the wax is within the above range, it is more preferable from the viewpoint of achieving both blocking resistance and hot offset resistance of the toner.

In the present invention, the toner particles may contain a colorant. Examples of the colorant used include the following.

Examples of the colorant for black toner include those colored black with carbon black; a yellow colorant, a magenta colorant, and a cyan colorant. Although the pigment may be used alone as the colorant, it is more preferable to improve the sharpness by using the dye and the pigment in combination from the viewpoint of the image quality of the full-color image.

Examples of the magenta toner pigment include the following. C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 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, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269, 282; C.I. I. Pigment Violet 19; C.I. I. Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

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 Disper 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 cyan toner pigment include the following. C. I. Pigment Blue 2, 3, 15: 2, 15: 3, 15: 4, 16, 17; C.I. I. Bat Blue 6; C.I. I. Acid blue 45, a copper phthalocyanine pigment in which a phthalocyanine skeleton is substituted with 1 or more and 5 or less phthalimide methyl groups.
As the dye for cyan toner, C.I. I. There is Solvent Blue 70.

Examples of the pigment for yellow toner include the following. C. 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, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; C.I. I. Bat Yellow 1, 3, 20.
Examples of the dye for yellow toner include C.I. I. There is Solvent Yellow 162.

The content of the colorant is preferably 0.1 parts by mass or more and 30.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

In the present invention, the toner particles may contain a charge control agent, if necessary.
As the charge control agent, known ones can be used, but in particular, a metal compound of an aromatic carboxylic acid which is colorless, has a high charge speed of the toner, and can stably maintain a constant charge amount is preferable.

Negative charge control agents include salicylate metal compounds, naphthoic acid metal compounds, dicarboxylic acid metal compounds, polymer compounds having sulfonic acid or carboxylic acid in the side chain, sulfonates or sulfonic acid esterified products in the side chain. Examples thereof include a high molecular weight compound, a high molecular weight compound having a carboxylate or a carboxylic acid esterified product in a side chain, a boron compound, a urea compound, a silicon compound, and a calix array.

Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, and an imidazole compound.

The charge control agent may be added internally or externally to the toner particles.
The content of the charge control agent is preferably 0 parts by mass or more and 0.1 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

The toner of the present invention may contain other inorganic fine particles other than silica fine particles A, if necessary.
The inorganic fine particles may be internally added to the toner particles or may be mixed with the toner particles as an external additive.
When contained as an external additive, inorganic fine particles such as silica fine particles, titanium oxide fine particles, and aluminum oxide fine particles are preferable.
The inorganic fine particles are preferably hydrophobized with a hydrophobizing agent such as a silane compound, silicone oil or a mixture thereof.

When the inorganic fine particles are used for improving the fluidity of the toner, the specific surface area thereof is preferably 50 m ² / g or more and 400 m ² / g or less.
On the other hand, when the inorganic fine particles are used for improving the durability of the toner, the specific surface area thereof is preferably 10 m ² / g or more and 50 m ² / g or less.
In order to achieve both the improvement of fluidity and the improvement of durability, inorganic fine particles having a specific surface area in the above range may be used in combination.

When the inorganic fine particles are contained as an external additive, it is preferably 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100.0 parts by mass of the toner particles. A known mixer such as a Henschel mixer may be used for mixing the toner particles and the inorganic fine particles.

In the present invention, the method for producing the toner particles is not particularly limited, but it is preferable to use a melt-kneading method or an emulsion aggregation method, and it is more preferable to use a melt-kneading method.
Here, the melt-kneading method includes a step of melting and kneading a mixture containing a binder resin, a colorant, etc. to obtain a melt-kneaded product (hereinafter, also simply referred to as a “melt-kneading step”) of toner particles. It is a manufacturing method.

Hereinafter, a procedure for manufacturing toner particles using the melt-kneading method will be described.
First, in the raw material mixing step, a predetermined amount of a polyester resin, a colorant, or the like is mixed as a toner raw material, and the mixture is mixed.
As an example of the equipment used for the mixing, Henshell mixer (manufactured by Nippon Coke Co., Ltd.); Super mixer (manufactured by Kawata Co., Ltd.); Ribocorn (manufactured by Okawara Seisakusho Co., Ltd.); (Manufactured by); Spiral pin mixer (manufactured by Pacific Kiko Co., Ltd.); Ladyge mixer (manufactured by Matsubo Co., Ltd.), etc.
Next, the obtained mixture is melted and kneaded to melt the resins, and a colorant or the like is dispersed therein (melt kneading step).
As an example of the equipment used in the melt kneading process, TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Japan Steel Works); PCM kneader (manufactured by Ikegai Iron Works); Kneedex (Manufactured by Mitsui Mining Co., Ltd.) and the like. A continuous kneader such as a single-screw or twin-screw extruder is preferable to a batch kneader because of its superiority such as continuous production.

Next, the obtained melt-kneaded product is rolled by two rolls or the like and cooled by water cooling or the like.
The obtained coolant is pulverized to a desired particle size. First, it is roughly pulverized by a crusher, a hammer mill, a feather mill, or the like, and further finely pulverized by a Cryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), a super rotor (manufactured by Nisshin Engineering Co., Ltd.), or the like to obtain resin particles.
The obtained resin particles may be classified into desired particle sizes to be toner particles. Devices used for classification include turboplex, faculty, TSP, TTSP (manufactured by Hosokawa Micron); elbow jet (manufactured by Nittetsu Mining Co., Ltd.) and the like.
It is preferable that the weight average particle size of the obtained toner particles is 3.0 μm or more and 8.0 μm or less because the effect of the external additive according to the present invention can be sufficiently obtained. Further, the circularity of the toner particles may be increased by performing a treatment such as applying a mechanical impact force to the toner particles. The average circularity is preferably 0.946 or more and 0.972 or less in order to increase the chances of charge transfer and friction between toner particles and to increase the charge rise rate.

<Magnetic carrier>
Next, the magnetic carrier used in the present invention will be described.
As the magnetic carrier core used for the magnetic carrier of the present invention, a known magnetic carrier core can be used. It is more preferable to use magnetic material-dispersed resin particles in which the magnetic material is dispersed in the resin component, or porous magnetic core particles containing the resin in the voids.
Since these can reduce the true density of the magnetic carriers, the load on the toner can be reduced. This makes it possible to reduce the frequency of replacement of the developer composed of toner and carrier with little deterioration in image quality even after long-term use. However, the present invention is not limited to the above, and the effect of the present invention can be fully exhibited even if a commercially available magnetic carrier core is used.

The magnetic substance component used in the magnetic material dispersion type resin particles is selected from magnetite particle powder, maghemite particle powder, or an oxide of silicon, an oxide of silicon, an oxide of aluminum, and an oxide of aluminum. Magnetic iron oxide particle powder containing at least one; magnesiumplumbite type ferrite particle powder containing barium, strontium or barium-strontium; spinel type containing at least one selected from manganese, nickel, zinc, lithium and magnesium. Various magnetic iron compound particle powders such as ferrite particle powder can be used.
Among these, magnetic iron oxide particle powder can be preferably used.

Furthermore, in addition to the magnetic component, non-magnetic iron oxide particle powder such as hematite particle powder, non-magnetic hydroxide-containing ferrous iron particle powder such as gateite particle powder, titanium oxide particle powder, silica particle powder, and talc particle powder. , Alumina particle powder, barium sulfate particle powder, barium carbonate particle powder, cadmium yellow particle powder, calcium carbonate particle powder, zinc flower particle powder and other non-magnetic inorganic compound particle powder may be used in combination with magnetic iron compound particle powder. ..
When the magnetic iron compound particle powder and the non-magnetic inorganic compound particle powder are mixed and used, the mixing ratio thereof is preferably at least 30% by mass of the magnetic iron compound particle powder.
It is preferable that all or part of the magnetic iron compound particle powder is treated with a lipophilic treatment agent.
As the lipophilic treatment agent used in that case, one or more 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. Organic compounds having the same functional groups and mixtures thereof can be used.

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.

As the binder resin constituting the magnetic material dispersion type resin particles, a thermosetting resin is preferable.
For example, there are phenol resin, epoxy resin, unsaturated polyester resin and the like, but it is preferable that the phenol resin is contained because it is inexpensive and easy to manufacture. For example, a phenol-formaldehyde resin can be mentioned.

The content ratio of the binder resin constituting the composite particles in the present invention and the magnetic iron compound particle powder (or a mixture of the magnetic iron compound particle powder and the non-magnetic inorganic compound particle powder) is 1% by mass or more and 20% by mass of the binder resin. The following and the magnetic iron compound particle powder (or the mixture thereof) are preferably 80% by mass or more and 99% by mass or less.

Next, a method for producing the magnetically dispersed resin particles will be described.
For the composite particles, for example, as described in Examples described later, phenols and aldehydes are stirred in an aqueous medium in the presence of magnetic and non-magnetic inorganic compound particle powders and a basic catalyst. .. After that, there is a method of reacting and curing phenols and aldehydes to produce composite particles containing inorganic compound particles such as magnetic iron oxide particle powder and phenol resin.

It can also be produced by a so-called kneading pulverization method or the like, in which a binder resin containing inorganic compound particles such as magnetic iron oxide particle powder is pulverized. The former method is preferable in order to easily control the particle size of the magnetic carrier and obtain a sharp particle size distribution.

Next, the porous magnetic core particles will be described.
As the material of the porous magnetic core particles, magnetite or ferrite is preferable. Further, it is more preferable that the material of the porous magnetic core particles is ferrite because the porous structure of the porous magnetic core particles can be controlled and the resistance can be adjusted.
The porous magnetic core particles used in the present invention have a pore size distribution in which the peak pore size in the range of 0.1 μm or more and 3.0 μm or less is 0.40 μm or more and 1.00 μm or less. It is preferable from the viewpoint of change in followability and durability.
Similarly, the environmental change is that the pore volume, which is the integral value of the differential pore volume in the range of 0.1 μm or more and 3.0 μm or less in the pore diameter distribution, is 58 mm ³ / g or more and 100 mm ³ / g or less. It is preferable from the viewpoint of change in followability and durability.

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 and M2 is a divalent metal. When x + y + z = 1.0, x and y are 0 ≦ (x, y) ≦ 0.8, respectively, and z is 0.2 <z <1.0.)
In the formula, as M1 and M2, it is preferable to use at least one metal atom selected from the group consisting of Li, Fe, Mn, Mg, Sr, Cu, Zn and Ca. In addition, Ni, Co, Ba, Y, V, Bi, In, Ta, Zr, B, Mo, Na, Sn, Ti, Cr, Al, Si, rare earth and the like can also be used.

In the magnetic carrier, it is preferable to control the uneven state of the surface of the porous magnetic core particles in order to maintain an appropriate amount of magnetization and to keep the pore diameter in a desired range. Further, it is preferable that the rate of the ferrite formation reaction can be easily controlled and the specific resistance and magnetic force of the porous magnetic core particles can be suitably controlled. From the above viewpoint, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr-based ferrite, and Li-Mn-based ferrite containing Mn element are more preferable.

The manufacturing process when porous ferrite particles are used as the magnetic carrier core will be described in detail below.
<Process 1 (Weighing / mixing process)>
The above ferrite raw materials are weighed and mixed.
Examples of the ferrite raw material 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 mill, planetary mill, geot mill, vibration mill. A ball mill is particularly preferable from the viewpoint of mixing.
Specifically, weighed ferrite raw materials and balls are placed in a ball mill, and preferably pulverized and mixed for 0.1 hours or more and 20.0 hours or less.

<Step 2 (temporary firing step)>
The pulverized and mixed ferrite raw material is calcinated 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. For firing, for example, the following furnace is used. Examples include a burner type incinerator, a rotary type incinerator, and an electric furnace.

<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. Examples include crushers, hammer mills, ball mills, bead mills, planetary mills, and geot mills.
In order to obtain a desired particle size of the pulverized ferrite product, for example, it is preferable to control the material, particle size, and operation time of the balls and beads used in the ball mill and the bead mill. Specifically, in order to reduce the particle size of the calcined ferrite slurry, a ball 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, it can be obtained by using balls or beads having a heavy specific gravity and shortening the pulverization time. Further, by mixing a plurality of calcined ferrites having different particle sizes, calcined ferrites having a wide distribution can be obtained.
Further, in ball mills and bead mills, the wet method is higher than the dry method because the crushed product does not fly up in the mill and the crushing efficiency is high. For this reason, wet type is more preferable than dry type.

<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 and ammonium carbonate.
Examples of the resin fine particles include polyester, polystyrene, styrene-vinyltoluene copolymer, styrene-vinylnaphthalin copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, and styrene-α-chloromethacrylic. Styre copolymers such as methyl acid acid copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethylketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-inden copolymer Combined; Polyvinyl chloride, phenol resin, modified phenol resin, malein resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin; aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohols And polyester resin having a monomer selected from diphenols as a structural unit; polyurethane resin, polyamide resin, polyvinyl butyral, terpene resin, kumaron inden resin, petroleum resin, polyester unit and vinyl polymer unit. Examples include fine particles of a hybrid resin.
As the binder, for example, polyvinyl alcohol is used.

In the case of wet pulverization in step 3, it is preferable to add a binder and a pore adjusting agent if necessary in consideration of 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. The spray dryer is not particularly limited as long as the desired particle size of the porous magnetic core particles can be obtained. For example, a spray dryer can be used.

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

<Process 6 (sorting process)>
After crushing the particles fired as described above, coarse particles and fine particles may be removed by classification or sieving with a sieve, if necessary.
From the viewpoint of carrier adhesion to the image and suppression of roughness, 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.

<Step 7 (filling step)>
The physical strength of the porous magnetic core particles may be low depending on the internal pore volume, and in order to increase the physical strength as a magnetic carrier, at least a part of the voids of the porous magnetic core particles is made of resin. It is preferable to perform filling. The amount of the 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. However, 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. Examples thereof include a method of impregnating and then volatilizing the solvent. 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.
The solvent used here may be any solvent that can dissolve the resin. When the resin is soluble in an organic solvent, examples of the organic solvent include toluene, xylene, cellsolve butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and methanol. In the case of a water-soluble resin or an emulsion type resin, water may be used as the solvent.
The amount of the resin solid content in the resin solution is preferably 1% by mass or more and 50% by mass or less, and more preferably 1% by mass or more and 30% by mass or less. When it is 50% by mass or less, the viscosity is not too high and the resin solution easily permeates uniformly into the voids of the porous magnetic core particles. On the other hand, when it is 1% by mass or more, the amount of the resin is appropriate, and the adhesive force of the resin to the porous magnetic core particles becomes good.

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 it has a high affinity for porous magnetic core particles. 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. Examples thereof include novolak resin, saturated alkyl polyester resin, polyarylate, polyamide resin, acrylic resin and the like.
Further, examples of the thermosetting resin include the following. Examples thereof include phenolic resins, epoxy resins, unsaturated polyester resins, and silicone resins.

The method of coating the surface of the magnetic carrier core particles with a resin is not particularly limited, and examples thereof include a method of coating by a dipping method, a spraying method, a brush coating method, a dry method, and a coating method such as a fluidized bed.
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, and tin oxide.
The amount of the conductive particles added 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 in order to adjust 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 amount of 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 coated resin in order to adjust the triboelectric charge amount.
The content of the resin coating layer present on the surface of the magnetic carrier is preferably 1.0 part by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the magnetic carrier core. When the content is 1.0 part by mass or more, the toughness and wear resistance of the resin are enhanced, and the change in image density is suppressed. On the other hand, when the content is 3.0 parts by mass or less, the charge mitigation property is further enhanced, and the density unevenness in the image plane and the deterioration of the fine line reproducibility are further suppressed.

The magnetic carrier preferably has a current value of 10.0 μA or more and 100.0 μA or less when 500 V is applied. When the current value is 10.0 μA or more, uneven density in the image plane and deterioration of character quality are further suppressed. On the other hand, when the current value is 100.0 μA or less, it is possible to suppress so-called “fog” in which the toner that is not sufficiently charged is transferred to the non-image portion.
The magnetic carrier preferably has a specific resistance value of 1.0 × 10 ⁵ Ω · cm or more and 1.0 × 10 ¹⁰ Ω · cm or less at an electric field strength of 2000 V / cm. When the specific resistance value is 1.0 × 10 ⁵ Ω ・ cm or more, “fog” is suppressed, and when the specific resistance value is 1.0 × 10 ¹⁰ Ω ・ cm or less, the density unevenness in the image surface and the character quality are improved. The decrease is more suppressed.

When the toner of the present invention is mixed with a magnetic carrier and used as a two-component developer, the carrier mixing ratio at that time is 2% by mass or more and 15% by mass or less, preferably 4% by mass, as the toner concentration in the developer. When it is% or more and 13% by mass or less, good results are usually obtained. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if it exceeds 15% by mass, fog and in-machine scattering are likely to occur.

Further, in the replenishing developer for replenishing the developer according to the decrease in the toner concentration of the two-component developer in the developing device, the amount of toner is 2 parts by mass or more and 50 parts by mass with respect to 1 part by mass of the replenishing magnetic carrier. It is less than a part.
Here, the replenishing developer is a developing agent that replenishes the replenishing developer to the developer according to the decrease in the toner concentration of the two-component developer in the developing device. The electrostatic latent image formed on the surface of the electrostatic latent image carrier is developed using the two-component developer in the developing device, and the excess magnetic carrier inside the developing device is removed from the developing device as needed. It is intended for use in a two-component developing method for discharging.

Next, an image forming apparatus provided with a developing apparatus using a two-component developer and a supplementary developer will be described with reference to an example, but the present invention is not limited thereto.

<Image formation method>
In FIG. 1, the electrostatic latent image carrier 1 rotates in the direction of an arrow in the figure. The electrostatic latent image carrier 1 is charged by a charging device 2 which is a charging means (charging step), 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. , Forming an electrostatic latent image (electrostatic latent image forming step). 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 electrostatic latent image carrier 1.

The two-component developer is held on the developer carrier 6 by the magnetic field of the magnet 7, the amount of the two-component developer is regulated by the regulating member 8, and 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. Then, by applying a development bias formed by superimposing an alternating electric field on a DC electric field, the electrostatic latent image is visualized as a toner image using a two-component developer in the developing device (development process). The toner image formed on the electrostatic latent image carrier 1 is electrostatically transferred to the recording medium 12 by the transfer charging device 11 without interposing the intermediate transfer body (transfer step).

Here, as shown in FIG. 2, the electrostatic latent image carrier 1 is temporarily transferred to the intermediate transfer body 9 (via the intermediate transfer body), and then electrostatically transferred to the transfer material (recording medium) 12. You may. 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 (fixing step). After that, the recording medium 12 is discharged to the outside of the apparatus 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 irradiation with light from the pre-exposure 16, and the image forming operation is repeated.

FIG. 2 shows an example of 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. 2, the electrostatic latent image carriers 1K, 1Y, 1C, and 1M rotate in the direction of the arrow 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 on the developing means 4K, 4Y, 4C, and 4M. It is visualized. Further, it is transferred to the intermediate transfer body 9 by the intermediate transfer charging device 10K, 10Y, 10C, 10M which is a 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 member 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 possible to apply an AC voltage to the developer carrier 6 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. preferable. The distance (distance between SD) between the developer carrier (development sleeve) 6 and the electrostatic latent image carrier 1 is 100 μm or more and 1000 μm or less, which is good for preventing carrier adhesion and improving dot reproducibility. be. When it is 100 μm or more, the supply of the developer is sufficient 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 coat carrier is increased, and carrier adhesion 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 Hz or more and 7000 Hz or less, and each of them 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. Occasionally, in order to respond to changes 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, sufficient image density can be easily obtained, and fog toner in the non-image portion can be easily collected. 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 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. 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, when the frequency is lower than 500 Hz, the configuration of the electrostatic latent image carrier may be the same as that of a photoconductor usually used in an image forming apparatus, although it is related to the process speed. 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.

<Measurement of weight average particle size (D4) of toner particles>
The weight average particle size (D4) of the toner particles is measured with a precision particle size distribution measuring device "Colter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter) equipped with a 100 μm aperture tube by the pore electric resistance method. Measurement data is measured with 25,000 effective measurement channels using the attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting conditions and analyzing measurement data. Is analyzed and calculated.
As the electrolytic aqueous solution used for the measurement, a special grade sodium chloride dissolved in ion-exchanged water so as to have a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter) can be used.

Before performing measurement and analysis, set the dedicated software as follows.
In the "Change standard measurement method (SOM) screen" of the dedicated software, set the total count number of the control mode to 50,000 particles, measure once, and set the Kd value to "Standard particles 10.0 μm" (Beckman Coulter). Set the value obtained using (manufactured by the company). 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, the electrolytic aqueous solution to ISOTON II, and check the flash of the aperture tube after measurement.
In the dedicated software "Pulse to particle size conversion setting screen", set the bin spacing to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm or more and 60 μm or less.

The specific measurement method is as follows.
(1) Put about 200 ml of the electrolytic aqueous solution in a 250 ml round bottom beaker made of glass dedicated to Multisizer 3, set it on a sample stand, and stir the stirrer rod counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "aperture flash" function of the dedicated software.

(2) Approximately 30 ml of the electrolytic aqueous solution is placed in a 100 ml flat-bottomed beaker made of glass, and "Contaminone N" (nonionic surfactant, anionic surfactant, organic builder) is used as a dispersant in the electrolytic aqueous solution for precise measurement of pH 7. Add about 0.3 ml of a diluted solution obtained by diluting a 10% by mass aqueous solution of a neutral detergent for cleaning a vessel, manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water 3 times by mass.

(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. A predetermined amount of ion-exchanged water is added, and about 2 ml of the Contaminone N is added into the water tank.

(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic solution in the beaker is maximized.

(5) With the electrolytic aqueous solution in the beaker of (4) being 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. For 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 is dispersed is dropped onto the round bottom beaker of (1) installed in the sample stand, and the measured concentration is adjusted to about 5%. .. Then, the measurement is performed until the number of measured particles reaches 50,000.

(7) The measurement data is analyzed by the dedicated software attached to the device, and the weight average particle size (D4) is calculated. The "average diameter" of the analysis / volume statistical value (arithmetic mean) screen when the graph / volume% is set by the dedicated software is the weight average particle diameter (D4).

<Measuring method of average circularity>
The average circularity of the toner particles is measured by the flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions at the time of calibration work.
The specific measurement method is as follows. First, about 20 ml of ion-exchanged water from which impure solids and the like have been removed in advance is placed in a glass container. Among them, as a dispersant, "Contaminone N" (a 10% by mass aqueous solution of a neutral detergent for cleaning a pH 7 precision measuring instrument consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd. ) Is diluted about 3 times by mass with ion-exchanged water, and about 0.2 ml of the diluted solution is added. Further, about 0.02 g of the measurement sample is added, and the dispersion treatment is performed for 2 minutes using an ultrasonic disperser to prepare a dispersion liquid for measurement. At that time, the dispersion liquid is appropriately cooled so that the temperature is 10 ° C. or higher and 40 ° C. or lower. As the ultrasonic disperser, a desktop ultrasonic cleaner disperser (“VS-150” (manufactured by Vervocrea)) with an oscillation frequency of 50 kHz and an electrical output of 150 W is used, and a predetermined amount of ions are contained in the water tank. Add exchange water, and add about 2 ml of the Contaminone N to this water tank.

The flow-type particle image analyzer equipped with a standard objective lens (10x) was used for the measurement, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion liquid adjusted according to the above procedure is introduced into the flow type particle image analyzer, and 3000 toner particles are measured in the HPF measurement mode and the total count mode. Then, the binarization threshold value at the time of particle analysis is set to 85%, the diameter of the analyzed particle is limited to 1.985 μm or more and less than 39.69 μm, and the average circularity of the toner particles is obtained.

In the measurement, automatic focus adjustment is performed using standard latex particles (“RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A” manufactured by Duke Scientific) diluted with ion-exchanged water before the start of the measurement. After that, it is preferable to perform focus adjustment every two hours from the start of measurement.

In the embodiment of the present application, a flow-type particle image analyzer that has been calibrated by Sysmex and has received a calibration certificate issued by Sysmex was used. The measurement was performed under the measurement and analysis conditions at the time of receiving the calibration certification, except that the diameter of the analysis particle was limited to the equivalent circle diameter of 1.985 μm or more and less than 39.69 μm.

<Measurement of specific resistance of magnetic carrier>
The specific resistance of the magnetic carrier is measured using the measuring device outlined in FIG. The magnetic carrier measures the specific resistance at an electric field strength of 2000 (V / cm).
The resistance measurement cell A is a cylindrical container (made of PTFE resin) 17 with a hole having a cross-sectional area of 2.4 cm ² , a lower electrode (made of stainless steel) 18, a support pedestal (made of PTFE resin) 19, and an upper electrode (made of stainless steel). It is composed of 20. A cylindrical container 17 is placed on the support pedestal 19, the sample (magnetic carrier) 21 is filled to a thickness of about 1 mm, and the upper electrode 20 is placed on the filled sample 21 to measure the thickness of the sample. As shown in FIG. 3A, the gap when there is no sample is d1, and as shown in FIG. 3B, the gap d2 when the sample is filled so as to have a thickness of about 1 mm is used as the sample. The thickness d of is calculated by the following formula.
d = d2-d1 (mm)
At this time, the mass of the sample is appropriately changed so that the thickness d of the sample is 0.95 mm or more and 1.04 mm or less.

The specific resistance of the sample can be obtained by applying a DC voltage between the electrodes and measuring the current flowing at that time. An electrometer 22 (Kesley 6517A, manufactured by Kessley) and a processing computer 23 for control are used for the measurement.
A control system and control software (LabVEIW National Instruments Co., Ltd.) manufactured by National Instruments Co., Ltd. are used as a processing computer for control.
As the measurement conditions, input the measured value d so that the contact area S between the sample and the electrode is 2.4 cm ² , and the thickness of the sample is 0.95 mm or more and 1.04 mm or less. Further, the load of the upper electrode is 270 g, and the maximum applied voltage is 1000 V.
Specific resistance (Ω · cm) = (applied voltage (V) / measured current (A)) × S (cm ² ) / d (cm)
Electric field strength (V / cm) = applied voltage (V) / d (cm)
For the specific resistance of the magnetic carrier at the electric field strength, the specific resistance at the electric field strength on the graph is read from the graph.

<Measurement of pore diameter and pore volume of porous magnetic core particles>
The pore size distribution of the porous magnetic core particles is measured by the mercury intrusion method.
The measurement principle is as follows.
In this measurement, the pressure applied to mercury is changed, and the amount of mercury that has penetrated into the pores at that time is measured. The conditions under which mercury can penetrate into the pores can be expressed as PD = -4σCOSθ from the balance of power, assuming that the pressure P, the pore diameter D, the contact angle of mercury and the surface tension are θ and σ, respectively. If the contact angle and surface tension are constants, the pressure P and the pore diameter D through which mercury can penetrate at that time are inversely proportional. Therefore, the horizontal axis P of the PV curve, which can be measured by changing the pressure for the pressure P and the infiltrated liquid amount V at that time, is directly replaced with the pore diameter from this equation, and the pore distribution is obtained. There is.

As the measuring device, a fully automatic multi-function mercury porosimeter PoreMaster series / PoreMaster-GT series manufactured by Yuasa Ionics Co., Ltd., an automatic porosimeter Autopore IV 9500 series manufactured by Shimadzu Corporation, or the like can be used for measurement.
Specifically, the measurement is performed using the Autopore IV9520 manufactured by Shimadzu Corporation under the following conditions and procedures.
Measurement conditions Measurement environment 20 ° C
Measurement cell Sample volume 5 cm ³ , press-fit volume 1.1 cm ³ , application Powder measurement range 2.0 psia (13.8 kPa) or more, 59989.6 psia (413.7 kPa) or less Measurement step 80 steps
(When the pore diameter is taken logarithmically, the steps are carved so that they are evenly spaced.)
Press-fitting parameter Exhaust pressure 50 μmHg
Exhaust time 5.0min
Mercury injection pressure 2.0 psia (13.8 kPa)
Equilibrium time 5 secs
High pressure parameter Equilibrium time 5 secs
Mercury parameter forward contact angle 130.0 degrees
Receding contact angle 130.0 degrees
Surface tension 485.0 mN / m (485.0 days / cm)
Mercury density 13.535g / mL

Measurement procedure (1) Weigh about 1.0 g of porous magnetic core particles and put them in a sample cell.
Enter the weighing value.
(2) Measure the range of 2.0 psia (13.8 kPa) or more and 45.8 psia (315.6 kPa) or less in the low pressure section.
(3) Measure the range of 45.9 psia (316.3 kPa) or more and 59989.6 psia (413.6 kPa) or less in the high pressure part.
(4) The pore size distribution is calculated from the mercury injection pressure and the mercury injection amount.
(2), (3) and (4) are automatically performed by the software attached to the device.
From the pore size distribution measured as described above, the pore diameter that maximizes the differential pore volume in the range of pore diameters of 0.1 μm or more and 3.0 μm or less is read, and the differential pore volume becomes maximum accordingly. The pore diameter.
Further, the pore volume obtained by integrating the differential pore volume in the pore diameter range of 0.1 μm or more and 3.0 μm or less is calculated using the attached software and used as the pore volume.

<P / C measurement method>
The measurement of the ratio (P / C) of the phosphorus element content (P) and the carbon element content (C) in the coating material is performed using an X-ray photoelectron spectroscopic analyzer.
Specifically, using the X-ray photoelectron spectroscopic analyzer "K-Alpha" (manufactured by Thermo Fisher Scientific Co., Ltd.), quantitative analysis of phosphorus element and carbon element is performed under the following analysis conditions, and the atomic peak area of each is performed. The surface element concentration is calculated from the above, and the value of the ratio (P / C) of the surface element concentration (P) of the phosphorus element and the surface element concentration (C) of the carbon element is calculated.

(Preparation of sample)
A dried resin is placed in a hole (diameter 3 mm, depth 1 mm) of a powder measuring plate, and the surface is scraped off as a measurement sample.

(Measurement condition)
X-ray: Al monochrome source acceleration: 12kV, 6mA
Beam system: 400 μm
Path energy: 50eV
Step size: 0.1eV

<Measuring method of number average particle size of primary particles of silica fine particles A>
The number average particle size of the primary particles of silica fine particles A is calculated from the silica fine particles A image on the surface of the toner particles taken by Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation). Will be done. The image shooting conditions of S-4800 are as follows.
The observation conditions for S-4800 are set, and the average particle size of the number of primary particles of the silica fine particles A is calculated using the image obtained by observing the backscattered electron image of S-4800. Since the backscattered electron image has less particle charge-up than the secondary electron image, the particle size can be measured with high accuracy.
The particle size of at least 300 silica fine particles A on the surface of the toner particles is measured to determine the average particle size. Here, since some of the silica fine particles A exist as agglomerates, the maximum diameter of what can be confirmed as the primary particles is obtained, and the obtained maximum diameter is arithmetically averaged to obtain an average number of primary particles of the silica fine particles A. Get the diameter.

<Measuring method of the content of metal elements in silica fine particles A>
<Extraction of silica fine particles A from toner>
Silica fine particles A are extracted from the toner by a water washing treatment method. Specifically, 6 mL of the following Contaminone N is placed in the following 30 mL glass vial in a sucrose aqueous solution in which 31.1 g of sucrose (manufactured by Kishida Chemical Co., Ltd.) is dissolved in 10.3 g of ion-exchanged water. Mix well to prepare a dispersion.
Contaminon N: Neutral detergent for cleaning precision measuring instruments with pH 7 consisting of nonionic surfactant, anionic surfactant, and organic builder, glass vial manufactured by Wako Pure Chemical Industries, Ltd .: manufactured by Nichiden Rika Glass Co., Ltd., VCV-30, outer diameter: 35 mm, height: 70 mm
1.0 g of toner is added to this glass vial and allowed to stand until the toner naturally settles to prepare a pretreatment dispersion. This dispersion is shaken with a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) at a shaking speed of 200 rpm for 5 minutes to separate the silica fine particles A from the surface of the toner particles. The toner particles and the silica fine particles A desorbed from the surface of the toner particles are separated by using a centrifuge. The centrifugation step is performed at 3700 rpm for 30 minutes. The silica fine particles A separated from the surface of the toner particles and the toner are collected by suction filtration and dried to obtain the silica fine particles A and the toner after washing with water.

<Measurement of metal element content in silica fine particles A>
Fluorescent X-ray measurement is performed on the silica fine particles A obtained by repeating the above water washing treatment method, and the iron atom content is calculated.
The fluorescent X-ray measurement of each element conforms to JIS K 0119-1969, but the specifics are as follows.
As the measuring device, for example, a wavelength dispersive fluorescent X-ray analyzer "Axios" (manufactured by PANalytical) is used.
Weigh 2 g of a sample on a cup with a dedicated PP (polypropylene) film attached to the bottom surface of a cup dedicated to powder measurement recommended by PANalytical, and form a uniform thickness layer on the bottom surface and cover it. Then, the elements from Na to U in the silica particles are measured by the FP method under the atmospheric pressure He atmosphere. At that time, assuming that all the detected elements are oxides, the total mass of them is 100%, and the content (mass%) of Fe2O3 with respect to the total mass is oxidized by software SpectraEvolution (version 5.0L). Obtained as a converted value.

<Measurement method of charge attenuation constant α of silica fine particles A>
The charge decay constant α of the external additive used for each of the magnetic carriers and toners was calculated using a static electricity diffusion rate measuring device (trade name: NS-D100, manufactured by Nanoseeds), JIS C 61340-2-1. Do it in a way that complies with.
-Sample set Put the external additive in an aluminum sample pan (a recess with an inner diameter of 10 mm and a depth of 1 mm is formed).
Then, using a flat plate, the external additive is pushed in from above and filled by grinding.
-Leaving in the environment Place the sample pan filled with the external additive on the aluminum sample cell and leave it for 12 hours or more in an environment with a temperature of 23 ° C and a relative humidity of 50%.
-Charging Place the grounded sample cell in the measuring instrument and charge the sample for 0.1 seconds by corona discharge.
-Measurement of potential The surface potential is measured for 1800 seconds immediately after the end of corona discharge. The surface potential at the start of measurement is set to the initial surface potential V0, and the charge attenuation constant α is calculated from the surface potential transition up to 1800 seconds according to the following equation.
ln (Vt / V0) =-αt (1/2)
(In the above equation, V indicates the surface potential (V), Vt indicates the surface potential (V) after t seconds, V0 indicates the initial surface potential (V), and α indicates the charge decay constant (α). 1 / s (1/2)), where t indicates the decay time (seconds).)

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

<Production example of silica fine particles A1>
The silica fine particles A1 were produced by the diffusion combustion method as follows.
In producing the silica fine particles A1, a hydrocarbon-oxygen mixed burner having a double tube structure in which an internal flame and an external flame were formed was used as a combustion furnace. This burner is configured such that a two-fluid nozzle for slurry injection is grounded at the center of the burner and a raw material silicon compound is introduced. Further, a flammable gas of hydrocarbon-oxygen is injected from the periphery of the bifluid nozzle to form an inner flame and an outer flame which are reducing atmospheres. By controlling the amount and flow rate of flammable gas and oxygen, the atmosphere, temperature, flame length, etc. can be adjusted.
Further, in a flame, silica fine particles are generated from the raw material silicon compound, and the silica fine particles can be fused until the desired particle size is obtained. Then, it is cooled and the generated silica fine particles are collected by a bag filter or the like to obtain silica fine particles A having a desired particle size.
As the raw material silicon compound, a hexamethylcyclotrisiloxane compound containing 150 ppm of iron atoms was used to produce silica fine particles A1.
Next, 100 parts by mass of the obtained silica fine particles A was surface-treated with 4% by mass of hexamethyldisilazane to obtain silica fine particles A1.
Table 1 shows the number average particle diameters of the obtained primary particles of the silica fine particles A1. Table 1 shows the iron content contained in the silica fine particles A1 and the charge attenuation constant α under a 23 ° C. and 50% RH environment.

<Production example of silica fine particles A2 to 13>
In the production example of the silica fine particles A1, the silica fine particles A2 to 13 were obtained by changing the number average particle size and the iron content of the primary particles. Table 1 shows the average particle size of the number of primary particles of each silica fine particle, the particle size of the silica bond, the iron content, and the charge attenuation constant α under a 23 ° C. and 50% RH environment.

<Toner manufacturing example>
<Production example of amorphous polyester resin>
<Production example of low molecular weight amorphous polyester resin (L)>
-Polyoxypropylene (2.8) -2,2-bis (4-hydroxyphenyl) propane
: 76.6 parts (0.17 mol; 100.0 mol% with respect to the total number of moles of polyhydric alcohol)
-Terephthalic acid: 17.4 parts (0.10 mol; 72.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
-Adipic acid: 6.0 parts (0.04 mol; 28.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
-Titanium tetrabutoxide (esterification catalyst): 0.5 parts The above materials were weighed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen introduction tube, and a thermocouple.
Next, the inside of the reaction vessel was replaced with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 4 hours while stirring at a temperature of 200 ° C.
Further, the pressure in the reaction vessel was lowered to 8.3 kPa, maintained for 1 hour, cooled to 180, and returned to atmospheric pressure (first reaction step).
-Tart-butylcatechol (polymerization prohibitor): 0.1 part After that, the above material was added, the pressure in the reaction vessel was lowered to 8.3 kPa, and the reaction was carried out for 1 hour while maintaining the temperature at 180 ° C., ASTM D36- After confirming that the softening point of the reactant measured according to 86 reached 90 ° C., the temperature was lowered to stop the reaction (second reaction step), and an amorphous polyester resin (L) was obtained. The obtained amorphous polyester resin (L) has a peak molecular weight (Mp) of 5000, a softening point (Tm) of 90 ° C., a glass transition temperature (Tg) of 52 ° C., an acid value of 5 mgKOH / g, and a hydroxyl value. It was 10 mgKOH / g.

<Production example of high molecular weight amorphous polyester resin (H)>
-Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane
: 72.2 parts (0.20 mol; 100.0 mol% with respect to the total number of moles of polyhydric alcohol)
-Terephthalic acid: 13.2 parts (0.08 mol; 48.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
-Adipic acid: 8.2 parts (0.06 mol; 34.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
-Titanium tetrabutoxide (esterification catalyst): 0.5 parts by mass The above materials were weighed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen introduction tube, and a thermocouple.
Next, the inside of the reaction vessel was replaced with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 2 hours while stirring at a temperature of 200 ° C.
Further, the pressure in the reaction vessel was lowered to 8.3 kPa, maintained for 1 hour, cooled to 160, and returned to atmospheric pressure (first reaction step).
Trimellitic acid: 6.3 parts (0.03 mol; 18.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
-Tart-butylcatechol (polymerization prohibitor): 0.1 part After that, the above material was added, the pressure in the reaction vessel was lowered to 8.3 kPa, and the reaction was carried out for 15 hours while maintaining the temperature at 160 ° C., ASTM D36- After confirming that the softening point of the reactant measured according to 86 reached 140 ° C., the temperature was lowered to stop the reaction (second reaction step), and an amorphous polyester resin (H) was obtained. The obtained amorphous polyester resin (H) has a peak molecular weight (Mp) of 8700, a softening point (Tm) of 142 ° C., a glass transition temperature (Tg) of 57 ° C., an acid value of 20 mgKOH / g, and a hydroxyl value. It was 10 mgKOH / g.

<Manufacturing example of toner 1>
・ Low molecular weight amorphous polyester resin (L) 70.0 parts ・ High molecular weight amorphous polyester resin (H) 30.0 parts ・ Fischer-Tropsch wax 5.0 parts (hydrocarbon wax, peak of maximum heat absorption peak) Temperature is 90 ° C)
・ C. I. Pigment Blue 15: 3 7.0 parts Mix the above materials with a Henschel mixer (FM-75 type, manufactured by Nippon Coke Industries Co., Ltd.) at a rotation speed of 20s ^-1 and a rotation time of 5 min, and then set the temperature to 150 ° C. It was melted and kneaded with a twin-screw kneader (PCM-30 type, manufactured by Ikekai Iron Works Co., Ltd.). The obtained melt-kneaded product was cooled and coarsely pulverized with a hammer mill to 1 mm or less to obtain a coarsely crushed product. The obtained coarse crushed product was finely pulverized with a mechanical crusher (T-250, manufactured by Turbo Industries, Ltd.). Further, classification was performed using Faculty F-300 (manufactured by Hosokawa Micron Co., Ltd.) to obtain toner matrix particles 1. The operating conditions of the faculty F-300 were a classification rotor rotation speed of 130s ^-1 and a distributed rotor rotation speed of 120s ^-1 .
To 100 parts of toner matrix particles 1, 1.0 part of hydrophobic silica (number average particle size: 20 nm) and 1: 2.0 parts of silica fine particles A are added to a Henshell mixer (FM-75 type, Nippon Coke Industries, Ltd.). The rotation speed is 30s ^-1 , and the rotation time is 10 min. Toner 1 was obtained.
The weight average particle size (D4) of the toner 1 was 6.5 μm, and the average circularity was 0.950.

<Manufacturing example of toners 2 to 13>
Toners 2 to 13 were obtained in the same manner as in the production example of toner 1 except that the type of silica fine particles A was changed as shown in Table 2. The weight average particle size (D4) of the toners 2 to 13 was 6.5 μm, and the average circularity was 0.950.

<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 the mixed slurry is dried by a spray dryer (manufactured by Okawara Kakohki 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 set to 70% by mass. The slurry was obtained by grinding with a wet ball mill using 1/8 inch stainless beads for 3 hours. Further, this slurry was pulverized with a wet bead mill using zirconia having a diameter of 1 mm for 4 hours to obtain a calcined ferrite slurry having a volume-based 50% particle diameter (D50) of 1.3 μm.

Process 4 (granulation process)
To 100 parts of the calcined ferrite slurry, 1.0 part of ammonium polycarboxylate as a dispersant and 1.5 parts of polyvinyl alcohol as a binder are added, and then granulated into spherical particles by a spray dryer (manufactured by Okawara Kakohki Co., Ltd.). , Dry. 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 a dispersant and a binder.

Step 5 (firing step)
Under a nitrogen atmosphere (oxygen concentration 1.0% by volume), the time from room temperature to the firing temperature (1100 ° C.) was set to 2 hours, and the temperature was maintained at 1100 ° C. for 4 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, sieve them with a sieve with a mesh size of 150 μm to remove coarse particles, perform wind classification to remove fine particles, and then remove low magnetic force by magnetic dressing to remove porous magnetic core particles. I got 1.
The peak pore diameter of the obtained porous magnetic core particles was 0.60 μm, and the pore volume was 75 mm ³ / g.
100 parts of porous magnetic core particles 1 are placed in a stirring vessel of a mixing stirrer (Universal stirrer NDMV type manufactured by Dalton), kept at a temperature of 60 ° C., and methyl silicone oligomer at normal pressure: 95.0% by mass. , Γ-Aminopropyltrimethoxysilane: 5 parts of a packed resin composed of 5.0% by mass was added dropwise.
After the completion of the dropping, stirring was continued while adjusting the time, the temperature was raised to 70 ° C., and the particles of each porous magnetic core were filled with the resin composition.
The resin-filled magnetic core particles obtained after cooling are transferred to a mixer (drum mixer UD-AT type manufactured by Sugiyama Heavy Industries, Ltd.) having spiral blades in a rotatable mixing container, and at 2 ° C./ The temperature was raised to 140 ° C. with stirring at a heating rate of 1 minute. After that, heating and stirring were continued at 140 ° C. for 50 minutes.
After that, the particles were cooled to room temperature, and the ferrite particles filled with the resin and cured were taken out, and the non-magnetic material was removed using a magnetic dressing machine. Further, coarse particles were removed with a vibrating sieve to obtain a magnetic carrier core 1 filled with a resin.

<Manufacturing example of magnetic carrier core 2>
To 100.0 parts of magnesium powder having an average particle size of 0.30 μm, 4.0 parts of a silane coupling agent (3- (2-aminoethylamino) propyltrimethoxysilane) was added, and the mixture was placed in a container. The fine particles were treated by mixing and stirring at high speed at 100 ° C. or higher.
・ 10 parts of phenol ・ 6 parts of formaldehyde solution (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 in a state in which the magnetic material was dispersed.

<Manufacturing example of magnetic carrier core 3>
Weigh the raw materials so that MnO: 35 mol%, MgO: 14.5 mol%, Fe _{2O 3} : 50 mol% and SrO: 0.5 mol%, mix with water, and then use a wet media mill. The slurry was obtained by grinding for 5 hours. The obtained slurry was dried with a spray dryer to obtain spherical particles. The mixture was heated at 950 ° C. for 2 hours, pre-baked, pulverized for 1 hour in a wet ball mill using stainless beads having a diameter of 0.5 cm, and then pulverized for 4 hours using zirconia beads having a diameter of 0.3 cm. An appropriate amount of a dispersant is added to this slurry, and for the purpose of ensuring the strength of the granulated particles, polyvinyl alcohol resin (PVA) as a binder is added in an amount of 0.8% by mass based on the solid content, and then by a spray dryer. The particles were granulated, dried, and kept in an electric furnace at a temperature of 1275 ° C. and an oxygen concentration of 2.5% by volume (nitrogen gas atmosphere) for 5 hours for main firing. Then, it was crushed, further classified to adjust the particle size, and then the low magnetic force products were separated by magnetic dressing to prepare a magnetic carrier core 3.

<Production example of coating resin 1>
The monomers A and B shown in Table 3 are added to a four-necked flask equipped with a reflux cooler, a thermometer, a nitrogen suction tube and a rubbing type stirrer, and further, 3.0 parts of toluene and methyl ethyl ketone are added. After adding 3.0 parts and 0.072 parts of azobisisovaleronitrile and keeping at 80 ° C. for 10 hours under a nitrogen stream, Table 3 shows potassium polyoxyethylene alkyl ether potassium phosphate as a compound containing a phosphorus element or a sulfur element. The above-mentioned amount was added to obtain one coating resin solution (solid content 35% by mass).
Further, using the raw materials shown in Table 3, coating resins 2 to 20 were obtained in the same manner.

<Manufacturing example of magnetic carrier 1>
-Magnetic carrier core 1 100 parts-Coating resin 1 3.00 parts Magnetic carrier core 1: 100 parts, the coated resin 1 was diluted with toluene so that the resin component was 5%, and the resin was sufficiently stirred. The solution was prepared. After that, the magnetic carrier core 1 was put into a planetary motion type mixer (Nautamixer VN type manufactured by Hosokawa Micron Co., Ltd.) maintained at a temperature of 60 ° C., and the above resin solution was put into it. As a method of charging, 1/2 amount of the resin solution was charged, and the solvent was removed and the coating operation was performed for 30 minutes. Then, a further 1/2 amount of the resin solution was added, and the solvent was removed and the coating operation was performed for 40 minutes.
After that, the magnetic carrier coated with the resin coating layer is transferred to a mixer having spiral blades (drum mixer UD-AT type manufactured by Sugiyama Heavy Industries, Ltd.) in a rotatable mixing container, and the mixing container is rotated 10 times per minute. While stirring, heat treatment was performed at a temperature of 120 ° C. for 2 hours under a nitrogen atmosphere. The obtained magnetic carrier was separated into low magnetic force products by magnetic beneficiation, passed through a sieve having an opening of 150 μm, and then classified by a wind power classifier to obtain magnetic carrier 1. The specific resistance of the magnetic carrier ¹ was 8.0 × 109 Ω · cm.

<Manufacturing example of magnetic carriers 2 to 22>
Magnetic carriers 2 to 22 were obtained in the same manner as in the production example of magnetic carrier 1 except that the types of the magnetic carrier core and the coating resin were changed as shown in Table 4. The specific resistance values of the magnetic carriers 2 to 22 were 8.0 × ¹⁰⁹ Ω · cm.

Using toners 1 to 13 and magnetic carriers 1 to 22, each material is shaken with a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) so that the toner concentration becomes 8% by mass, and two components are used. 300 g of the system developer was prepared. The amplitude condition of the shaker was 200 rpm for 2 minutes.

On the other hand, using toners 1 to 13 and magnetic carriers 1 to 22, each material was prepared in an environment of room temperature and humidity of 23 ° C./50% RH for 5 minutes by a V-type mixer so that the carrier concentration was 8% by mass. Mixing gave a replenishing developer. Table 5 shows the details of the two-component developer, and Table 6 shows the details of the supplementary developer.

<Examples 1 to 28 and Comparative Examples 1 to 6>
The following evaluations were performed using the obtained two-component developer and supplementary developer.
As an image forming apparatus, a Canon color copier imagePRESS C850 remodeling machine was used.

When forming an image, the developer contained in the cyan-colored developing machine is replaced with the above-mentioned two-component developing agents 1 to 34, and the replenishing developer contained in the cyan-colored replenishing developer container is used. Was replaced with the above-mentioned replenishing developer 1-34. The modification points are as follows.
(1) The development contrast was made adjustable by an arbitrary value, and it was modified so that the automatic correction by the main body would not work.
(2) The AC component of the development bias was set to a frequency of 2.0 kHz, and the voltage between peaks (Vpp) was modified so that it could be changed from 0.7 kV to 1.8 kV in increments of 0.1 kV.
(3) It was modified so that an image could be formed in a single color.
Using the above modified machine, laser beam printer paper CS-814 (81.4 g / m ² ) (available from Canon Marketing Japan Co., Ltd.) was used as the transfer paper to form an image in a single cyan color. Evaluation test was conducted.

Each evaluation item is shown below.
(1) Initial environmental difference evaluation After leaving the evaluator under N / L environment (temperature 23 ° C / humidity 5RH%) and H / H environment (temperature 30 ° C / humidity 80RH%) for 48 hours, the image ratio 5 100 sheets of the% FFH output chart were passed. Note that FFH is a value in which 256 gradations are displayed in hexadecimal, 00h is the first gradation of 256 gradations (white background portion), and FFH is the 256th gradation of 256 gradations (solid portion). Is.
After passing 100 sheets of paper, 9 patches having an FFH density of 1 cm × 1 cm were arranged on the paper at equal intervals in the vertical and horizontal directions to output an image. The reflection density of all patches is measured using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite), the average value is calculated, and the difference in image density between the N / L environment and the H / H environment is calculated. Calculated. This concentration difference was evaluated based on the evaluation criteria shown below.
(Evaluation criteria)
A: Concentration difference: less than 0.03 B: Concentration difference: 0.03 or more and less than 0.06 C: Concentration difference: 0.06 or more and less than 0.10 D: Concentration difference: 0.10 or more and less than 0.13 E: Concentration difference: 0.13 or more and less than 0.16 F: Concentration difference: 0.16 or more and less than 0.20 G: Concentration difference: 0.20 or more and less than 0.25 H: Concentration difference: 0.25 or more

(2) Durability evaluation After being left in an N / N environment (temperature 23 ° C / humidity 50 RH%) and in an H / H environment (temperature 30 ° C / humidity 80 RH%) for 48 hours, the image ratio in the N / N environment. Using a chart with an FFH output of 5% and a chart with an FFH output with an image ratio of 40% in an H / H environment, 300,000 images were output. During the durability test, an image was output in which nine patches having an FFH density of 1 cm × 1 cm were arranged at equal intervals in the vertical and horizontal directions on every 1,000 sheets. The reflection densitometers of all the patches were measured using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite), and the average value was calculated and used as the image density in the durable number of sheets. Then, the standard deviation of all image density variations during endurance was calculated. The standard deviation of this change in image density was evaluated based on the evaluation criteria shown below. During the 300,000-sheet continuous paper-passing period, the paper is passed under the same development conditions and transfer conditions (without calibration) as the first-sheet paper.
(Evaluation criteria)
A: Standard deviation: less than 0.02 B: Standard deviation: 0.02 or more and less than 0.04 C: Standard deviation: 0.04 or more and less than 0.06 D: Standard deviation: 0.06 or more and less than 0.08 E: Standard deviation: 0.08 or more and less than 0.10 F: Standard deviation: 0.10 or more and less than 0.15 G: Standard deviation: 0.15 or more and less than 0.20 H: Standard deviation: 0.20 or more

(3) Evaluation of leaving characteristics under high temperature and high humidity After the durability test in the H / H environment in (2) above, after leaving in the same environment for 48 hours, a 1 cm × 1 cm FFH concentration patch is applied on paper. One image was output in which nine images were arranged at equal intervals in the vertical and horizontal directions. The reflection densitometers of all patches were measured using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite), the average value was calculated, and the density difference from immediately after 300,000 sheets were passed was calculated. .. This concentration difference was evaluated based on the evaluation criteria shown below.
(Evaluation criteria)
A: Concentration difference: less than 0.03 B: Concentration difference: 0.03 or more and less than 0.06 C: Concentration difference: 0.06 or more and less than 0.10 D: Concentration difference: 0.10 or more and less than 0.13 E: Concentration difference: 0.13 or more and less than 0.16 F: Concentration difference: 0.16 or more and less than 0.20 G: Concentration difference: 0.20 or more and less than 0.25 H: Concentration difference: 0.25 or more

(4) Evaluation of color change after leaving After the evaluation of (3) above, the evaluation machine was moved to an N / L environment and left for 24 hours. After that, 100 sheets of FFH output chart with an image ratio of 5% are passed through, the reflection density of the printing unit is measured for all 100 sheets, and between the 1st to 50th sheets and the 51st to 100th sheets, respectively. The standard deviation of fluctuations in image density was calculated. The standard deviation of this change in image density was evaluated based on the evaluation criteria shown below. During the paper passing test, the paper is passed under the same development conditions and transfer conditions (without calibration) as the first sheet.
(Evaluation criteria)
A: Standard deviation: less than 0.02 B: Standard deviation: 0.02 or more and less than 0.04 C: Standard deviation: 0.04 or more and less than 0.06 D: Standard deviation: 0.06 or more and less than 0.08 E: Standard deviation: 0.08 or more and less than 0.10 F: Standard deviation: 0.10 or more and less than 0.15 G: Standard deviation: 0.15 or more and less than 0.20 H: Standard deviation: 0.20 or more

The evaluation results are shown in Table 7.

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: Cylindrical container, 18: Lower electrode, 19: Support pedestal, 20: Upper electrode, 21: Magnetic carrier or carrier core, 22: Electrometer, 23: Processing computer, d1: Gap when there is no sample, d2: Gap when filling the sample

Claims (11)

A two-component developer containing toner and a magnetic carrier.
The toner is a toner having toner particles containing a binder resin and silica fine particles A present on the surface of the toner particles.
The silica fine particles A have an average number of primary particles of 80 nm or more and 200 nm or less.
The silica fine particles A have a charge attenuation constant α of 0.0005 or more and 0.0100 or less after 1800 seconds from being charged in an environment of a temperature of 23 ° C. and a relative humidity of 50%.
The magnetic carrier is a magnetic carrier having a magnetic carrier core and magnetic carrier particles having a resin coating layer formed on the surface of the magnetic carrier core.
The resin coating layer contains a resin containing a structural unit derived from the (meth) acrylic acid ester compound.
The resin coating layer is a two-component developer characterized by containing a phosphorus element or a sulfur element. The two-component developer according to claim 1, wherein the (meth) acrylic acid ester compound is an alicyclic (meth) acrylic acid ester compound. The two-component developer according to claim 2, wherein the alicyclic (meth) acrylic acid ester compound has a cycloalkyl group having 5 or more and 8 or less carbon atoms. The two-component developer according to claim 3, wherein the alicyclic (meth) acrylic acid ester compound is cyclohexyl (meth) acrylic acid. The two-component developer according to any one of claims 2 to 4, wherein the resin coating layer further contains a structural unit derived from a chain type (meth) acrylic acid ester compound. Any one of claims 2 to 5 in which the content of the structural unit derived from the alicyclic (meth) acrylic acid ester compound in the resin coating layer is 10.0% by mass or more and 90.0% by mass or less. The two-component developer described in the section. The two-component developer according to any one of claims 1 to 6, wherein the resin coating layer contains a phosphorus element. The two-component development according to claim 7, wherein the ratio (P / C) of the phosphorus element content (P) and the carbon element content (C) in the resin coating layer is 0.0010 or more and 0.0100 or less. Agent. The two-component developer according to claim 7 or 8, which contains the phosphorus element as a phosphoric acid group, an acidic phosphoric acid ester group or a salt group thereof, or a phosphoric acid ester group in the resin coating layer. A replenishing developer is replenished to the developer according to the decrease in the toner concentration of the two-component developer in the developing device, and the electrostatic latent image formed on the surface of the electrostatic latent image carrier is made into the two components in the developing device. A replenishing developer for use in a two-component developing method that develops with a system developer and discharges excess magnetic carriers inside the developer from the developer as needed.
The replenishing developer is a two-component developer according to any one of claims 1 to 9, wherein the toner amount with respect to 1 part by mass of the magnetic carrier is 2 parts by mass or more and 50 parts by mass or less. A replenishing developer characterized by. A charging step of 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, and a two-component developer in the developer for the electrostatic latent image. A developing step of developing using and forming a toner image, 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 having an image forming method, wherein the two-component developing agent according to any one of claims 1 to 9 is used as the two-component developing agent.

Images