JP2022115805A - Magnetic carrier, two-component developer, and developer for replenishment - Google Patents

Abstract

To provide a magnetic carrier that exhibits excellent contamination resistance and abrasion resistance.SOLUTION: A magnetic carrier includes a magnetic core and coating resin coating the surface of the magnetic core, the coating resin contains resin A and resin B, contents of the resin A are 1 mass% or more and 50 mass% or less and contents of the resin B are 50 mass% or more and 99 mass% or less on the basis of the coating resin, the resin A has a specific unit Y1 and a specific unit Y2, the resin B contains 0.1 mass% or less of the specific unit Y2, a formula (a) 0.90≤(a+b)/X≤1.00 and a formula (b) 1.00≤a/b≤30.0 are satisfied when the mass of the resin A is X, the mass of the unit Y1 in the resin A is a, and the mass of the unit Y2 in the resin A is b, and a formula (c) 0≤|SPa-SPb|≤2.0 is satisfied when a SP value of the unit Y1 is SPa and a SP value of the resin B is SPb.SELECTED DRAWING: None

Description

The present invention relates to a magnetic carrier, a two-component developer, and a developer for replenishment, which are used in an image forming method for visualizing an electrostatic charge image using electrophotography.

Conventionally, in the electrophotographic image forming method, an electrostatic latent image is formed on an electrostatic latent image carrier using various means, and toner is adhered to the electrostatic latent image to form the electrostatic latent image. Developing methods are commonly used. For this development, carrier particles called magnetic carriers are mixed with the toner, triboelectrically charged to impart an appropriate amount of positive or negative charge to the toner, and the charge is used as a driving force for development. Two-component development is widely used. Adopted.

In the two-component development method, functions such as agitating, transporting, and charging the developer can be added to the magnetic carrier, so the division of functions with the toner is clear. There is Here, the magnetic carrier often has a structure in which the core is coated with a core for imparting magnetism to acquire transportability and a coating resin for acquiring the ability to impart charge to the toner.

In recent years, due to technological advances in the field of electrophotography, a higher level of long life is required for the main body, and it is required that the carrier maintains its charge-imparting ability even in long-term use. It is known that due to the reduction of charging sites due to the adhesion of toner components, the ability to impart charge is lowered, causing image defects such as changes in color tone.

As a means for obtaining the above-described durability against adhesion of toner components (hereinafter referred to as "stain resistance"), an example of using a material having a low surface free energy such as silicone resin as a coating resin is taken (Patent Document 2). 1).

JP-A-2002-91093 JP 2015-138230 A Japanese Unexamined Patent Application Publication No. 2013-3428

However, in general, materials with low surface free energy such as silicone resin can suppress the adhesion of toner components, etc., but the interaction between molecules is weak and they are easily destroyed by external forces. . For this reason, if a silicone resin is used as the carrier coating resin, the coating resin may wear out due to the mechanical load that occurs during stirring or transportation in the developing machine (hereinafter referred to as "wear resistance"). However, as a result of the decrease in the surface resistance of the carrier due to the abrasion of the coating resin, the charging ability of the carrier may decrease (Patent Documents 1 to 3).

In order to obtain the above abrasion resistance, it is conceivable to use a silicone-modified resin with trifunctional silicon bonded to the terminal. It is known that the properties do not improve (Patent Document 2). On the other hand, when a resin having a silicone structure in a side chain is used as a structure to further reduce the surface free energy, the surface free energy between molecules is reduced, so the above-mentioned silicone resin was used. As in the case, it has been confirmed that the wear resistance becomes insufficient (Patent Document 3).

In other words, in order to realize a highly stable carrier, it is required to obtain both contamination resistance for suppressing the adhesion of toner components and abrasion resistance for suppressing abrasion of the coat due to mechanical load and the like at the same time.

In view of the above, the object of the present invention is to provide a contamination-resistant toner that achieves reduction in fogging, reduction in toner scattering, stable image density, and developability even in long-term use in a two-component development type image forming method. and abrasion resistance.

As a result of intensive studies, the present inventors have found that the use of resin A and resin B shown in the structure below makes it possible to obtain contamination resistance and abrasion resistance of the carrier.
Resin A has a structure in which a silicone structure similar to that of the silicone resin is grafted onto the main chain, and this silicone structure causes a decrease in surface free energy and improves stain resistance. . Moreover, since the resin B has a structure having high compatibility with the main chain of the resin A, the resin A and the resin B are mixed, thereby improving the abrasion resistance. As described above, when only a resin having a silicone structure grafted thereto such as resin A was used, the wear resistance of the carrier was insufficient. By using them together, strong interaction between the main chain of resin A and resin B makes it possible to acquire abrasion resistance.

That is, one embodiment of the present invention has a magnetic core and a coating resin that coats the surface of the magnetic core,
The coating resin contains resin A and resin B,
Based on the total mass of the coating resin, the content of the resin A is 1% by mass or more and 50% by mass or less, and the content of the resin B is 50% by mass or more and 99% or less,
The resin A has a unit Y1 represented by the following formula (1) and a unit Y2 represented by the following formula (2),
In the resin B, the content of the unit Y2 represented by the following formula (2) is 0.1% by mass or less,
When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, the X, the a, and the b are represented by the following formula. (a), (b)
0.90≦(a+b)/X≦1.00 (a)
1.00≤a/b≤30.0 (b)
The filling,
When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the SPa and SPb are represented by the following formula (c)
0≦|SPa−SPb|≦2.0 (c)
(in formula (1),
R ₁ represents H or CH ₃ ,
R ₂ represents a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, and the substituent is a hydroxy group or a carboxy group. )
(In formula (2),
R3 represents H or _{CH3 ,
R4} represents H or _CH3 ,
R ₅ represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms,
R ₆ represents a hydrocarbon group having 1 to 10 carbon atoms,
_R7 represents H, _CH3 or Si( _CH3 ) ₃ ,
n represents an integer of 2 or more and 150 or less. )
It is to provide a magnetic carrier.

Another aspect of the present invention is to provide a two-component developer comprising the magnetic carrier and the toner.
Another aspect of the present invention is to provide a replenishing developer comprising the magnetic carrier and the toner.

According to the present invention, it is possible to provide a stable carrier with stain resistance and wear resistance that achieves reduced fogging, reduced toner scattering, stable image density, and developability even in long-term use. .

It is an example of the schematic of a surface treatment apparatus. 1 is an example of a schematic diagram of an image forming apparatus; FIG. 1 is an example of a schematic diagram in which an image forming method is applied to a full-color image forming apparatus; FIG. 1 is a schematic diagram of a device for measuring the resistivity of a magnetic carrier and a porous magnetic core; FIG.

In the present invention, unless otherwise specified, the descriptions of "○○ or more and XX or less" and "○○ to XX", which represent numerical ranges, mean numerical ranges including the lower and upper limits that are endpoints.

A magnetic carrier of the present invention is a magnetic carrier having a magnetic core and a coating resin that coats the surface of the magnetic core,
The coating resin contains resin A and resin B,
Based on the total mass of the coating resin, the content of the resin A is 1% by mass or more and 50% by mass or less, and the content of the resin B is 50% by mass or more and 99% or less,
The resin A has a unit Y1 represented by the following formula (1) and a unit Y2 represented by the following formula (2),
In the resin B, the content of the unit Y2 represented by the following formula (2) is 0.1% by mass or less,
When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, the X, the a, and the b are represented by the following formula. (a), (b)
0.90≦(a+b)/X≦1.00 (a)
1.00≤a/b≤30.0 (b)
The filling,
When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the SPa and SPb are represented by the following formula (c)
0≦|SPa−SPb|≦2.0 (c)
is characterized by satisfying
(In formula (1),
R ₁ represents H or CH ₃ ,
R ₂ represents a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, and the substituent is a hydroxy group or a carboxy group. )
(In formula (2),
R3 represents H or _{CH3 ,
R4} represents H or _CH3 ,
R ₅ represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms,
R ₆ represents a hydrocarbon group having 1 to 10 carbon atoms,
_R7 represents H, _CH3 or Si( _CH3 ) ₃ ,
n represents an integer of 2 or more and 150 or less. )

As described above, when only a resin having a low surface free energy such as a silicone resin is used as the coating resin, the wear resistance deteriorates. The carrier of the present invention has a resin A and a resin B. The resin A has a structure similar to that of the silicone resin, and has a structure in which this structure is grafted to the main chain. , the surface free energy derived from the silicone structure is lowered, and the stain resistance is improved. In addition, as described later, the resin B has a structure having high compatibility with the main chain of the resin A, so that the resin A and the resin B are subjected to mechanical load such as shear caused by a developing machine. It becomes difficult for peeling to occur due to abrasion, and wear resistance improves.

The resin A has a unit Y1 represented by the above formula (1) and a unit Y2 represented by the following formula (2). The unit Y2 has a silicone structure, which lowers the surface free energy and improves the contamination resistance.

In the formula (1), the unit Y1 is represented by R ₁ representing H or CH ₃ and R ₂ representing a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, preferably having a substituent. is an alkyl group having 1 to 6 carbon atoms which may be substituted. Substituents on R ₂ are hydroxy or carboxy groups. As a specific method for introducing R ₁ and R ₂ , for example, they can be introduced by copolymerizing the following monomers when the resin A is polymerized. Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, cyclobutyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, cyclooctyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacryl Butyl acid, hexyl methacrylate, cyclobutyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, cyclooctyl methacrylate, 2-hydroxyethyl acrylate, 2-carboxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-carboxy methacrylate ethyl.

In unit Y2, R ₃ represents H or CH ₃ , R ₄ represents H or CH ₃ , R ₅ represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. is an alkylene of R ₆ represents a hydrocarbon group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms or a phenyl group. _R7 represents H, _CH3 or Si( _CH3 ) ₃ , and n represents an integer of 2 or more and 150 or less. As a specific technique for introducing these substituents, for example, when the resin A is polymerized, an acrylic acid ester, a methacrylic acid ester, or a 2-butenoic acid ester in which the silicone structure is esterified is introduced by copolymerization. It is possible.

When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, the X, the a, and the b is the following formula (a), (b)
0.90≦(a+b)/X≦1.00 (a)
1.00≤a/b≤30.0 (b)
meet. This relational expression indicates that the resin A contains 90% by mass or more of the unit Y1 and the unit Y2 in all units, and that the unit Y2 has the same mass% as the unit Y1, multiplied by 30. . When (a+b)/X is less than 0.90, the compatibility with the resin B is lowered, resulting in deterioration of wear resistance, or the surface free energy is lowered, resulting in deterioration of stain resistance, which is not preferable. On the other hand, when a/b is less than 1.00, the ratio of the unit Y2 to the unit Y1 is too high, and the surface free energy becomes too small, resulting in poor wear resistance. Conversely, if a/b is greater than 30, the surface free energy becomes too high, resulting in poor stain resistance.

The proportion of resin A contained in the coating resin is 1 to 50% by mass. If the proportion of the resin A contained in the coating resin is less than 1% by mass, the surface free energy does not decrease, resulting in insufficient contamination resistance. When the proportion of resin A contained in the coating resin is greater than 50% by mass, the decrease in intermolecular force due to low surface free energy is greater than the wear resistance obtained through interaction with resin B. Therefore, wear resistance becomes insufficient. A preferable range of the ratio of the resin A contained in the coating resin is 1% by mass or more and 20% by mass or less, and a more preferable range is 3 to 20% by mass.

The proportion of resin B contained in the coating resin is 50 to 99% by mass. If the proportion of the resin B contained in the coating resin is less than 50% by mass, the strength of the resin will be insufficient, resulting in poor wear resistance. If the proportion of the resin B contained in the coating resin exceeds 99% by mass, the effect of the component with low surface free energy becomes insufficient, resulting in deterioration of stain resistance. Preferably, it is 80% by mass or more and 99% by mass or less.

When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the Spa and SPb are represented by the following formula (c)
0≦|SPa−SPb|≦2.0 (c)
meet.
The above SP value is calculated by the following method.
Formula: SP value = √(Ev/v) = √(ΣΔei/ΣΔvi)
In the formula, Ev: evaporation energy (J / mol),
v: molar volume (cm ³ /mol),
Δei: vaporization energy of each atom or atomic group;
Δvi: molar volume of each atom or atomic group.

Satisfying the above relational expression (c) enhances the compatibility with the resin A and the resin B and improves the abrasion resistance. If |SPa-SPb| is greater than 2.0, the compatibility between the resin A and the resin B is low, and the interaction between molecules is reduced, resulting in deterioration of abrasion resistance. The smaller |SPa−SPb| is, the higher the compatibility is, and when it is 1.0 or less, wear resistance is further improved, which is preferable.

The resin A preferably satisfies the following formula (d), where m is the sum of the number of units Y1 and Y2.
50≦m≦250 (d)
When m is 50 or more, the molecular weight is sufficiently high, so that abrasion resistance is further improved. further improve.

The magnetic carrier of the present invention preferably contains 1.0 atomic % or more and 15.0 atomic % or less of Si as determined by ESCA analysis of the surface of the magnetic carrier. When the Si content is 1.0 atomic % or more, the surface free energy of carriers can be lowered, so that the contamination resistance is further improved. When the Si content is 15.0 atomic % or less, the intermolecular interaction in the vicinity of the carrier surface is increased, so that the wear resistance is further improved.

The Si atom concentration is measured as follows.
<Method for measuring Si atom concentration by XPS>
Stick the magnetic carrier on the indium foil. At that time, the particles are evenly adhered so that the indium foil portion is not exposed.
The measurement conditions are as follows.
Device: PHI5000VERSAPROBE II (ULVAC-Phi, Inc.)
Irradiation: Al Kα ray Output: 25W 15kV
Pass Energy: 58.7 eV
Stepsize: 0.125eV
XPS peaks: C1s, O1s, Si2p, Ti2p, Sr3d

In the resin A, n in formula (2) indicates the length of the side chain formed by the silicone structure of the silicone graft structure. When n is 2 to 150, the surface free energy of the carrier coat resin can be lowered. If n is 1 or less, the surface free energy cannot be lowered, resulting in poor stain resistance. When n is larger than 150, the interaction between the resin A and the resin B becomes small, resulting in deterioration of abrasion resistance. When n is 5 or more and 60 or less, wear resistance and stain resistance are improved, which is preferable.

The resin A may have a functional group such as a nitrogen-containing group, a carboxyl group or a hydroxyl group. By having these, it becomes possible to suppress charge-up of the developer especially in a low-humidity environment. In addition, since the resin A has a hydroxyl value, the effect of hydrogen bonding is exhibited, and the abrasion resistance is further improved, which is preferable.

A preferable range of the acid value of Resin A when carboxyl groups are used is 5 to 100 mgKOH/mg. When the acid value of the resin A is 5 or more, the charge build-up is improved, and when the acid value of the resin A is 100 or less, the charge retention of the developer is improved.

When hydroxyl groups are used, the preferred range of the hydroxyl value of Resin A is 5 to 50 mgKOH/mg. When the hydroxyl value of the resin A is 5 or more, charge build-up is improved, and when the hydroxyl value of the resin A is 50 or less, the charge retention of the developer is improved.

In the resin B, when the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the Spa and SPb are represented by the following formula (c)
0≦|SPa−SPb|≦2.0 (c)
is preferably used, but the structure is not particularly limited, and resins such as acrylic resins, urethane resins, polyethylene, polyethylene terephthalate, polystyrene, and phenol resins can be used.

From the viewpoint that the SP value of resin B is closer to the SP value of resin A and the compatibility with resin A is enhanced, resin B is preferably an acrylic resin.

The structure of the resin B is preferable because having the unit Y1 reduces the SP value difference with the resin A, thereby increasing compatibility, and the resin B contains the unit Y1 in an amount of 75% by mass or more. Containing is more preferable.

式（３）において、Ｒ_８はシクロヘキシル基、シクロヘプチル基、シクロオクチル基、シクロペンチル基、シクロブチル基又はシクロプロピル基を表す。 The resin B preferably contains a unit Y3 represented by the following formula (3), and preferably contains 1% by mass or more and 75% by mass or less.

_In formula (3), R8 represents a cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclopentyl group, cyclobutyl group or cyclopropyl group.

Since the resin B has an alicyclic hydrocarbon group such as that contained in the unit Y3, the surface (coating surface) of the resin coating layer that coats the surface of the magnetic core becomes smooth, and the toner or the , which suppresses the adhesion of toner-derived components such as an external additive that imparts fluidity to the toner, and further improves stain resistance. Unit Y3 may contain only one type of structure, or may contain two or more types.

When synthesizing Resin B, the (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group is 50 parts by mass or more and 90 parts by mass or less when the total amount of monomers used for synthesizing Resin B is 100 parts by mass. is preferably used within the range of

The weight average molecular weight (Mw) of Resin B is preferably 20,000 or more and 120,000 or less, more preferably 30,000 or more and 100,000 or less, from the viewpoint of coating stability.

The acid value of Resin B is preferably 0 mgKOH/g or more and 3.0 mgKOH/g or less, more preferably 0 mgKOH/g or more and 2.8 mgKOH/g or less, and 0 mgKOH/g or more and 2.5 mgKOH/g or less. is particularly preferred. When the acid value of Resin B is 3.0 mgKOH/g or less, self-coagulation of the resin due to the influence of the acid value is less likely to occur, and the smoothness of the surface (coating surface) of the resin coating layer is less likely to decrease. The acid value of the resin B can be controlled by using a monomer having a polar group such as a carboxy group or a sulfo group (sulfonic acid group) when synthesizing the coating resin A and adjusting the addition amount of the monomer. However, since it is preferable that the acid value of Resin A is low, it is preferable not to use a monomer having a polar group. Even when a resin is synthesized using only ester bond-forming monomers, a slight acid value may be generated in the synthesized resin. It is considered that this is because a part of the ester bond is decomposed to generate a carboxyl group during synthesis (polymerization) of the resin.

Resin B is preferably a polymer (copolymer) obtained by copolymerizing a (meth)acrylate monomer having an alicyclic hydrocarbon group and a macromonomer. When a macromonomer is used in synthesizing the resin B, the adhesion between the resin coating layer and the magnetic core is improved, and the ability of the magnetic carrier to impart charge to the toner is improved.

The macromonomer is at least one selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, acrylonitrile and methacrylonitrile. is preferably a macromonomer obtained by polymerizing the

The weight average molecular weight (Mw) of the macromonomer is preferably 2000 or more and 10000 or less, more preferably 3000 or more and 8000 or less.

When synthesizing the resin B, the macromonomer is preferably used in a range of 5.0 parts by mass or more and 40.0 parts by mass or less when the total monomer used for the synthesis of the coating resin A is 100 parts by mass. .

When the resin B is synthesized, particularly by mixing the methacrylate ester monomer, the entanglement of the molecules is strengthened and the adhesion of the coating resin to the magnetic core is improved. As a result, the coating does not come off even when subjected to a load from an agitating member or the like of the developing device, and the ability to impart a stable charge amount can be maintained over a long period of time, making it possible to output high-quality images.

The resin coating of the present invention preferably contains conductive fine particles. The conductive fine particles can appropriately control the specific resistance of the electrophotographic carrier. As a result, the countercharge after the toner is developed can be released, and white spots can be suppressed. The content of the conductive fine particles added to the coating resin is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the coating resin. If the content of the conductive fine particles is less than 0.1 parts by mass, it is difficult to obtain the effect of adding the conductive fine particles. There is Examples of conductive fine particles include carbon black, titanium oxide, and silver.

In addition, the coating resin may contain fine particles for the purpose of enhancing the charge imparting ability to the toner and improving the releasability. The fine particles contained in the resin coating may be fine particles of either an organic material or an inorganic material. Microparticles are preferred. Crosslinked resins forming crosslinked resin fine particles include crosslinked polymethyl methacrylate resins, crosslinked polystyrene resins, melamine resins, guanamine resins, urea resins, phenol resins and nylon resins. Moreover, silica, an alumina, a titania etc. are mentioned as an inorganic fine particle.

The content of the fine particles in the coating resin is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the coating resin.

Known magnetic particles such as magnetite particles, ferrite particles, and magnetic substance-dispersed resin particles can be used as the magnetic core particles of the present invention. Among them, magnetic particles obtained by filling the pores of porous magnetic particles with a resin or magnetic substance-dispersed resin particles, that is, magnetic particles containing a magnetic oxide and a resin composition, reduce the specific gravity of the magnetic carrier. Therefore, it is preferable from the viewpoint of prolonging the life.

Reducing the specific gravity of the magnetic carrier, for example, reduces the load on the toner in the developer state in the developing device, prevents the toner components from adhering to the surface of the magnetic carrier, reduces the load between the carriers, and reduces the load on the resin. This leads to further suppression of peeling, chipping, and scraping of the coating layer. In addition, dot reproducibility can be improved, and high-definition images can be obtained.

As the resin to be contained in the pores of the porous magnetic particles, the copolymer resin used as the coating resin can be used, but not limited to this, and other known resins such as thermoplastic resins and thermosetting resins can be used. can be used.

As the thermoplastic resin, the copolymer used as the coating resin is preferable, but other than that, for example, the following may be mentioned. Polystyrene, polymethyl methacrylate, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinyl acetate, polyvinylidene fluoride Resins, fluorocarbon resins, perfluorocarbon resins, solvent-soluble perfluorocarbon resins, polyvinylpyrrolidone, petroleum resins, novolak resins, saturated alkyl polyester resins, polyethylene terephthalate, polybutylene terephthalate, aromatic polyester resins such as polyarylates, polyamide resins, polyacetal resins, Polycarbonate resin, polyethersulfone resin, polysulfone resin, polyphenylene sulfide resin, polyetherketone resin.

Examples of thermosetting resins include the following. Phenolic resins, modified phenolic resins, maleic resins, alkyd resins, epoxy resins, acrylic resins, unsaturated polyesters obtained by polycondensation of maleic anhydride, terephthalic acid and polyhydric alcohols, urea resins, melamine resins, urea-melamine resins , xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, glyptal resin, furan resin, silicone resin, polyimide, polyamideimide resin, polyetherimide resin, polyurethane resin.

As a method of filling the voids of the ferrite particles having a porous shape with the resin component, there is a method of diluting the resin component with a solvent and adding the porous magnetic core particles to the diluted solution. Any solvent may be used as long as it can dissolve each resin component. When the resin is soluble in an organic solvent, organic solvents such as toluene, xylene, cellosolve butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and methanol may be used. In the case of a water-soluble resin component or an emulsion-type resin component, water may be used. As a method for adding the resin component diluted with a solvent into the inside of the porous magnetic core particles, the resin component is impregnated by a coating method such as a dipping method, a spray method, a brush coating method, a fluidized bed method, and a kneading method, Then, the method of volatilizing a solvent is mentioned. In the case of filling with a thermosetting resin, after the solvent is volatilized, the temperature is raised to a temperature at which the resin used is cured to cause a curing reaction.

On the other hand, as a specific method for producing the magnetic material-dispersed resin particles, the following method can be mentioned. For example, submicron magnetic materials such as iron powder, magnetite particles, and ferrite particles are kneaded so as to be dispersed in a thermoplastic resin, pulverized to a desired carrier particle size, and, if necessary, subjected to thermal or mechanical spheroidization. It can be obtained by applying a chemical treatment. It is also possible to manufacture by dispersing the above magnetic material in a monomer and polymerizing the monomer to form a resin.

Resins in this case include vinyl resins, polyester resins, epoxy resins, phenol resins, urea resins, polyurethane resins, polyimide resins, cellulose resins, silicone resins, acrylic resins and polyether resins. The resin may be of one type or a mixed resin of two or more types. In particular, phenol resin is preferable in that it increases the strength of the magnetic core. The true density and specific resistance can be adjusted by adjusting the amount of magnetic material. Specifically, in the case of magnetic particles, it is preferable to add 70% by mass or more and 95% by mass or less to the carrier.

The magnetic core has a volume-based 50% diameter (D50) of 20 μm or more and 80 μm or less so that the coating resin can be uniformly coated, and the density of the developer magnetic brush is appropriately adjusted to prevent carrier adhesion and to obtain high-quality images. It is preferable to do

Good development is achieved when the specific resistance of the magnetic core is 1.0×10 ⁵ (Ω·cm) or more and 1.0×10 ¹⁴ (Ω·cm) or less at an electric field strength of 1000 (V/cm). It is preferable because it enables to obtain the characteristics.
The method of coating the magnetic core surface with the coating resin is not particularly limited, and any known method can be used. For example, there is a so-called immersion method in which a magnetic core and a coating resin solution are stirred while the solvent is volatilized to coat the surface of the magnetic core with the coating resin. Specific examples thereof include a universal mixing stirrer (manufactured by Fuji Paudal Co., Ltd.), Nauta Mixer (manufactured by Hosokawa Micron Co., Ltd.), and the like. There is also a method of spraying a coating resin solution from a spray nozzle while forming a fluidized bed to coat the surface of the magnetic core with the coating resin. Specific examples include Spiracoater (manufactured by Okada Seiko) and Spiraflow (manufactured by Freund Corporation). There is also a method in which the magnetic core is coated with the coating resin in the form of particles in a dry manner. Specifically, processing methods using devices such as Hybridizer (manufactured by Nara Machinery Works), Mechanofusion (manufactured by Hosokawa Micron), Hiflex Gral (manufactured by Fukae Powtech), Theta Composer (manufactured by Tokuju Kosakusho), etc. can be mentioned.

Next, the magnetic carrier will be explained.
The magnetic carrier preferably has a magnetization intensity of 40 (Am ² /kg) or more and 70 (Am ² /kg) or less under a magnetic field of 5000/4π (kA/m). When the strength of magnetization of the magnetic carrier is within the above range, the magnetic binding force to the developing sleeve is moderate, so the occurrence of carrier adhesion can be suppressed more satisfactorily. Moreover, since the stress applied to the toner in the magnetic brush can be reduced, deterioration of the toner and adhesion to other members can be suppressed satisfactorily.
In addition, the strength of magnetization of the magnetic carrier can be appropriately adjusted by the amount of resin contained.

The residual magnetization of the magnetic carrier is preferably 20.0 (Am ² /kg) or less, more preferably 10.0 (Am ² /kg) or less. When the residual magnetization of the magnetic carrier is within the above range, particularly good fluidity as a developer can be obtained, and good dot reproducibility can be obtained.

The magnetic carrier preferably has a true density of 2.5 (g/cm ³ ) or more and 5.5 (g/cm ³ ) or less, and preferably 3.0 (g/cm ³ ) or more and 5.0 (g/cm 3 ) or more. ³ ) is more preferably below. A two-component developer containing a magnetic carrier having a true density within this range imposes less load on the toner and suppresses adhesion of toner components to the magnetic carrier. Further, the true density in this range is preferable for the magnetic carrier in order to achieve both good developability in a low electric field strength and prevention of carrier adhesion.

The magnetic carrier preferably has a volume-based 50% diameter (D50) of 21 μm or more and 81 μm or less from the viewpoints of charge imparting ability to toner, suppression of carrier adhesion to image areas, and high image quality. More preferably, the volume-based 50% diameter (D50) of the magnetic carrier is 25 μm or more and 60 μm.

Next, the configuration of the toner preferable for achieving the object of the present invention will be described in detail below.
<Binder resin>
For the toner particles of the present invention, the following polymers can be used as the binder resin. Homopolymers of styrene and substituted products thereof such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene -Styrenic copolymers such as acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers; Resin; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin , polyethylene resin, polypropylene resin, and the like. Among them, it is preferable to use a polyester resin as a main component from the viewpoint of low-temperature fixability.

Monomers used in the polyester unit of the polyester resin include polyhydric alcohols (divalent or trivalent or higher alcohols), polyvalent carboxylic acids (divalent or trivalent or higher carboxylic acids), acid anhydrides thereof, or lower Alkyl esters are used. Here, in order to express "strain hardening" and to create a branched polymer, it is effective to partially crosslink within the molecule of the amorphous resin. is preferably used. Therefore, it is preferable that a carboxylic acid having a valence of 3 or higher, an acid anhydride thereof or a lower alkyl ester thereof, and/or an alcohol having a valence of 3 or higher are included as raw material monomers for the polyester unit.

As the polyhydric alcohol monomer used for the polyester unit of the polyester resin, the following polyhydric alcohol monomers can be used.

（式中、Ｒはエチレンまた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）で示されるジオール類；

（式（Ｂ）中、Ｒ’は－ＣＨ_２ＣＨ_２－、－ＣＨ_２－ＣＨ（ＣＨ_３）－、または－ＣＨ_２－Ｃ（ＣＨ_３）_２－であり、ｘ’およびｙ’はそれぞれ０以上の整数であり、ｘ’＋ｙ’の平均値は０以上１０以下である。）
が挙げられる。 Dihydric alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1, 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, also bisphenols represented by formula (A) and derivatives thereof;

(Wherein, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 or more and 10 or less.)
diols represented by formula (B);

(In formula (B), R' is -CH ₂ CH ₂ -, -CH ₂ -CH(CH ₃ )-, or -CH ₂ -C(CH ₃ ) ₂ -, and x' and y' are each It is an integer of 0 or more, and the average value of x'+y' is 0 or more and 10 or less.)
is mentioned.

Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, and 1,2,4-butanetriol. , 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene mentioned. Among these, glycerol, trimethylolpropane, and pentaerythritol are preferably used. These dihydric alcohols and trihydric or higher alcohols can be used alone or in combination.

As the polycarboxylic acid monomer used for the polyester unit of the polyester resin, the following polycarboxylic acid monomers can be used.

Examples of divalent carboxylic acid components include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid, anhydrides of these acids and Lower alkyl esters of these are included. Among these, maleic acid, fumaric acid, terephthalic acid and n-dodecenylsuccinic acid are preferably used.

Trivalent or higher carboxylic acids, their acid anhydrides and their lower alkyl esters include, for example, 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid and 1,2,4-naphthalenetricarboxylic acid. , 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra( methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, their acid anhydrides or their lower alkyl esters. Among these, 1,2,4-benzenetricarboxylic acid, ie, trimellitic acid or derivatives thereof, is particularly preferred because it is inexpensive and reaction control is easy. These bivalent carboxylic acids and trivalent or higher carboxylic acids can be used alone or in combination.

The method for producing the polyester unit of the present invention is not particularly limited, and known methods can be used. For example, the above alcohol monomer and carboxylic acid monomer are charged at the same time, polymerized through an esterification reaction or a transesterification reaction, and a condensation reaction to produce a polyester resin. Moreover, although the polymerization temperature is not particularly limited, it is preferably in the range of 180° C. or higher and 290° C. or lower. Polymerization catalysts such as titanium-based catalysts, tin-based catalysts, zinc acetate, antimony trioxide, and germanium dioxide can be used for the polymerization of the polyester units. In particular, the binder resin of the present invention is more preferably a polyester unit polymerized using a tin-based catalyst.

In addition, the polyester resin has an acid value of 5 mgKOH/g or more and 20 mgKOH/g or less, and a hydroxyl value of 20 mgKOH/g or more and 70 mgKOH/g or less. It is preferable from the viewpoint of fog resistance because the adhesive force can be kept low.

Also, the binder resin may be a mixture of a low-molecular-weight resin and a high-molecular-weight resin. From the viewpoint of low-temperature fixability and hot-offset resistance, the content ratio of the high-molecular-weight resin and the low-molecular-weight resin is preferably 40/60 or more and 85/15 or less on a mass basis.

<Release agent>
Examples of waxes used in the toner of the present invention include the following. Hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymers, microcrystalline wax, paraffin wax and Fischer-Tropsch wax; oxides of hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; Waxes containing fatty acid ester as a main component such as carnauba wax; partially or wholly deoxidized fatty acid ester such as deoxidized carnauba wax. Furthermore, the following are mentioned. saturated straight-chain fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid and valinaric acid; saturated alcohols such as silyl alcohol; polyhydric alcohols such as sorbitol; fatty acids such as palmitic acid, stearic acid, behenic acid and montanic acid; Esters with alcohols such as silalcohol; Fatty acid amides such as linoleic acid amide, oleic acid amide and lauric acid amide; saturated fatty acid bisamides such as acid amides; unsaturated fatty acid amides such as ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N,N'dioleyladipic acid amide, N,N'dioleylsebacic acid amide; - aromatic bisamides such as xylene bisstearic acid amide and N,N' distearyl isophthalic acid amide; aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally called metal soap) waxes obtained by grafting vinyl monomers such as styrene and acrylic acid to aliphatic hydrocarbon waxes; partial esters of fatty acids and polyhydric alcohols such as behenic acid monoglyceride; hydrogen of vegetable oils and fats A methyl ester compound having a hydroxyl group obtained by addition.

Among these waxes, hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax, or fatty acid ester waxes such as carnauba wax are preferred from the viewpoint of improving low-temperature fixability and fixability. In the present invention, hydrocarbon waxes are more preferable in terms of further improving hot offset resistance.

In the present invention, the wax is preferably used in an amount of 3 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the binder resin.

Moreover, in the endothermic curve during temperature rise measured by a differential scanning calorimeter (DSC), the peak temperature of the maximum endothermic peak of the wax is preferably 45° C. or higher and 140° C. or lower. When the peak temperature of the maximum endothermic peak of the wax is within the above range, the storage stability and hot offset resistance of the toner can be compatible, which is preferable.

<Colorant>
The toner particles in the invention may contain a colorant. Colorants include the following.

Examples of black colorants include those toned black using carbon black; a yellow colorant, a magenta colorant and a cyan colorant. A pigment may be used alone as a coloring agent, but it is more preferable to use a dye and a pigment in combination to improve the definition from the viewpoint of image quality of a full-color image.

Examples of magenta toner pigments 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; I. Pigment Violet 19; C.I. I. Bat Red 1, 2, 10, 13, 15, 23, 29, 35.
Dyes for magenta toner 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. 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 cyan toner pigments 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 having a phthalocyanine skeleton substituted with 1 to 5 phthalimidomethyl groups.
As dyes for cyan toners, C.I. I. Solvent Blue 70 can be mentioned.

Examples of yellow toner pigments 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; I. Bat Yellow 1, 3, 20.
As a yellow toner dye, C.I. I. Solvent Yellow 162 is mentioned.

These colorants can be used singly or in combination, or in the form of a solid solution. Colorants are selected in terms of hue angle, chroma, brightness, lightfastness, OHP transparency, and dispersibility in toner.
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 the total amount of the resin components.

<Inorganic fine particles>
The toner preferably contains inorganic fine particles for the main purpose of improving fluidity and chargeability, and is preferably in the form of adhering to the surface of the toner.

Silica particles having a maximum peak particle size of 80 nm or more and 200 nm or less based on the number distribution are preferable as the inorganic fine particles as spacer particles for enhancing the releasability between the toner and the carrier. In order to better suppress detachment from the toner while functioning as spacer particles, the maximum peak particle diameter based on the number distribution is more preferably 100 nm or more and 150 nm or less.

In addition, in order to improve the fluidity of the toner, it is preferable to contain inorganic fine particles having a maximum peak particle size of 20 nm or more and 50 nm or less based on the number distribution.

Furthermore, other external additives may be added to the toner particles with the aim of improving fluidity and transferability. The external additive externally added to the surface of the toner particles preferably contains inorganic fine particles such as titanium oxide, alumina oxide and silica, and a plurality of types may be used in combination.

The total content of the external additive is preferably 0.3 parts by mass or more and 5.0 parts by mass or less, and 0.8 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. It is more preferable to have Among them, the content of silica particles having a maximum peak particle size of 80 nm or more and 200 nm or less based on number distribution is 0.1 parts by mass or more and 2.5 parts by mass or less, more preferably 0.5 parts by mass or more and 2.0 parts by mass It is below the department. If the content of silica particles having a maximum peak particle diameter of 80 nm or more and 200 nm or less based on number distribution is within this range, the effect as spacer particles becomes more pronounced.

In addition, it is preferable that the surfaces of silica particles and inorganic fine particles used as an external additive are subjected to a hydrophobic treatment. The hydrophobizing treatment is preferably carried out with coupling agents such as various titanium coupling agents and silane coupling agents; fatty acids and metal salts thereof; silicone oils; or combinations thereof.

Examples of titanium coupling agents include the following. Tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, bis(dioctyl pyrophosphate) oxyacetate titanate.

Moreover, as a silane coupling agent, the following are mentioned, for example. γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)γ - aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyl trimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane.

Examples of fatty acids include the following. Long-chain fatty acids such as undecylic acid, lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid. Metals of these fatty acid metal salts include, for example, zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

Examples of silicone oils include dimethylsilicone oil, methylphenylsilicone oil, and amino-modified silicone oil.

In the hydrophobization treatment, a hydrophobizing agent is added to the particles to be treated in an amount of 1% to 30% by mass (more preferably 3% to 7% by mass) relative to the particles to be treated. It is preferably carried out by coating.

The degree of hydrophobization of the hydrophobized external additive is not particularly limited. Hydrophobicity indicates the wettability of a sample to methanol, and is an index of hydrophobicity.

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. % or more and 13 mass % or less usually gives good results. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if the toner concentration exceeds 15% by mass, fogging and in-machine scattering tend to occur.

In addition, in the replenishing developer for replenishing the developing device according to the decrease in the toner concentration of the two-component developer in the developing device, the toner amount 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 below the department.

Next, an image forming apparatus equipped with a developing device using the magnetic carrier, the two-component developer, and the replenishing developer of the present invention will be described as an example. is not limited to

<Measurement of resistivity of magnetic carrier>
The resistivity of the magnetic carrier and the porous magnetic core are measured using the measuring apparatus outlined in FIG. The magnetic carrier measures the specific resistance at an electric field strength of 2000 (V/cm).
The resistance measuring cell A comprises 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 base (made of PTFE resin) 19, and an upper electrode (made of stainless steel). 20. A cylindrical container 17 is placed on a support pedestal 19, a sample (magnetic carrier or porous magnetic core) 21 is filled to a thickness of about 1 mm, an upper electrode 20 is placed on the filled sample 21, and the sample thickness is to measure. Assuming that the gap when there is no sample is d1 as shown in FIG. 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.
By applying a DC voltage between the electrodes and measuring the current flowing at that time, the specific resistance of the sample can be obtained. 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) manufactured by National Instruments were used as a processing computer for control.

As the measurement conditions, the contact area between the sample and the electrode is S=2.4 cm ² , and the measured value d is input so that the thickness of the sample is 0.95 mm or more and 1.04 mm or less. Also, the load on the upper electrode is 270 g and the maximum applied voltage is 1000V.
Specific resistance (Ω cm) = (applied voltage (V) / measured current (A)) × S (cm2) / d (cm)
Electric field strength (V/cm) = applied voltage (V)/d (cm)
The specific resistance of the magnetic carrier and the porous magnetic core at the electric field intensity is read from the graph of the specific resistance at the electric field intensity on the graph.

<Method for measuring volume-based 50% diameter (D50) of magnetic carrier and porous magnetic core>
The particle size distribution was measured using a laser diffraction/scattering type particle size distribution analyzer “Microtrac MT3300EX” (manufactured by Nikkiso Co., Ltd.).
The volume-based 50% diameter (D50) of the magnetic carrier and the porous magnetic core was measured by attaching a sample feeder for dry measurement "One-shot dry sample conditioner Turbotrac" (manufactured by Nikkiso Co., Ltd.). Turbotrac was supplied with a dust collector as a vacuum source, an air volume of about 33 l/sec, and a pressure of about 17 kPa. Control is performed automatically on software. As for the particle size, the 50% particle size (D50), which is the cumulative value of the volume distribution, is obtained. Control and analysis are performed using attached software (version 10.3.3-202D). Measurement conditions are as follows.
SetZero time: 10 seconds Measurement time: 10 seconds Number of measurements: 1 Particle refractive index: 1.81%
Particle shape: Non-spherical Measurement upper limit: 1408 µm
Measurement lower limit: 0.243 μm
Measurement environment: 23°C, 50% RH

<Measurement of Pore Diameter and Pore Volume of Porous Magnetic Core>
The pore size distribution of the porous magnetic core is measured by mercury porosimetry.
The measurement principle is as follows.
In this measurement, the pressure applied to the mercury is changed, and the amount of mercury that has penetrated into the pores is measured. The conditions under which mercury can penetrate into the pores can be expressed as PD=-4σCOSθ from the force balance, where θ and σ are the pressure P, the pore diameter D, the contact angle of mercury, and the surface tension. If the contact angle and surface tension are constants, the pressure P is inversely proportional to the pore diameter D into which mercury can enter. Therefore, the horizontal axis P of the PV curve, which can be obtained by measuring the pressure P and the infiltration liquid amount V at that time, by changing the pressure, is directly replaced by the pore diameter from this equation, and the pore distribution is obtained. there is

As a measuring device, a fully automatic multifunctional mercury porosimeter PoreMaster series/PoreMaster-GT series manufactured by Yuasa Ionics, an automatic porosimeter Autopore IV 9500 series manufactured by Shimadzu Corporation, or the like can be used.

Specifically, using Autopore IV9520 manufactured by Shimadzu Corporation, measurement was performed under the following conditions and procedures.
Measurement conditions Measurement environment 20°C
Measurement cell Sample volume 5 cm ³ Injection volume 1.1 cm ³ Application Powder Measurement range 2.0 psia (13.8 kPa) to 59989.6 psia (413.7 kPa) Measurement steps 80 steps
(When the pore diameter is taken logarithmically, the steps are carved so that they are evenly spaced.)
Injection parameters Exhaust pressure 50 μmHg
Exhaust time 5.0min
Mercury injection pressure 2.0 psia (13.8 kPa)
Equilibration time 5 secs
High pressure parameter Equilibration time 5 secs
Mercury parameters Advancing contact angle 130.0 degrees
receding contact angle 130.0 degrees
Surface tension 485.0 mN/m (485.0 dynes/cm)
Mercury density 13.5335g/mL

Measurement procedure (1) About 1.0 g of a porous magnetic core is weighed and placed in a sample cell.
Enter the weighing value.
(2) Measure the range of 2.0 psia (13.8 kPa) to 45.8 psia (315.6 kPa) at the low pressure section.
(3) Measure the range of 45.9 psia (316.3 kPa) to 59989.6 psia (413.6 MPa) at the high pressure section.
(4) Calculate the pore size distribution from the mercury injection pressure and the mercury injection amount.
(2), (3), and (4) were automatically performed using the software attached to the apparatus.
From the pore size distribution measured as described above, the pore size at which the differential pore volume is maximized in the pore size range of 0.1 μm or more and 3.0 μm or less is read, and the differential pore volume becomes maximum. Pore diameter.
Also, 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 was calculated using the accompanying software.

<Method for measuring weight average particle size (D4) and number average particle size (D1)>
The weight-average particle diameter (D4) and number-average particle diameter (D1) of the toner were measured by a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, Beckman Co., Ltd.) using a pore electrical resistance method equipped with a 100 μm aperture tube. Beckman Coulter Co., Ltd.) and attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (Beckman Coulter Co., Ltd.) for setting measurement conditions and analyzing measurement data. Measurement was performed with 25,000 effective measurement channels, and the measurement data was analyzed and calculated.
As the electrolytic aqueous solution used for measurement, a solution obtained by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.) can be used.

Before performing the measurement and analysis, the dedicated software was set as follows.
In the "change standard measurement method (SOM) screen" of the dedicated software, set the total number of counts in control mode to 50000 particles, set the number of measurements to 1, and set the Kd value to "standard particle 10.0 μm" (Beckman Coulter Co., Ltd. (manufactured) to set the value obtained using 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 electrolyte to ISOTON II, and check the flash of aperture tube after measurement.
In the "pulse-to-particle size conversion setting screen" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

A specific measuring method is as follows.
(1) About 200 ml of the electrolytic aqueous solution is placed in a 250 ml round-bottomed glass beaker exclusively for Multisizer 3, set on a sample stand, and stirred with a stirrer rod counterclockwise at 24 rpm. Then, use the analysis software's "flush aperture" function to remove dirt and air bubbles inside the aperture tube.
(2) About 30 ml of the electrolytic aqueous solution is placed in a 100 ml flat-bottom glass beaker. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for washing precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) is used as a dispersant. ) is diluted with ion-exchanged water to 3 times the mass, and about 0.3 ml of the diluted solution is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with a phase shift of 180 degrees, and placed in a water tank of an ultrasonic disperser with an electrical output of 120 W "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.). Add a certain amount of deionized water. About 2 ml of the contaminon N is added to this water bath.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.
(5) While the electrolytic aqueous solution in the beaker in (4) above is being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water in the water tank is appropriately adjusted to 10°C or higher and 40°C or lower.
(6) Using a pipette, drop the electrolytic aqueous solution of (5) in which the toner is dispersed into the round-bottomed beaker of (1) set in the sample stand, and adjust the measured concentration to about 5%. . The measurement is continued until the number of measured particles reaches 50,000.
(7) Analyze the measurement data with the dedicated software attached to the apparatus, and calculate the weight average particle size (D4) and the number average particle size (D1). In addition, when the graph/volume% is set with the dedicated software, the "average diameter" on the analysis/volume statistics (arithmetic mean) screen is the weight average particle size (D4), and the graph/number% is set with the dedicated software. The "average diameter" on the analysis/number statistical value (arithmetic mean) screen is the number average particle diameter (D1).

<Method for calculating the amount of fine powder>
The number-based fine powder amount (number %) in the toner is calculated as follows.
For example, the number % of particles of 4.0 μm or less in the toner can be measured by using the Multisizer 3 described above, and then (1) using dedicated software, set to graph/number % and display the chart of the measurement results as number %. do. (2) Check "<" in the particle size setting section on the format/particle size/particle size statistics screen, and enter "4" in the particle size input field below it. (3) When the analysis/number statistical value (arithmetic mean) screen is displayed, the numerical value in the "<4 μm" display portion is the number percent of particles of 4.0 μm or less in the toner.

<Method for calculating the amount of coarse powder>
The volume-based coarse powder amount (% by volume) in the toner is calculated as follows.
For example, the volume % of particles of 10.0 μm or more in the toner is measured by the above-mentioned Multisizer 3, and then (1) the dedicated software is set to graph/volume %, and the chart of the measurement result is displayed as volume %. do. (2) Check ">" in the particle size setting section on the format/particle size/particle size statistics screen, and enter "10" in the particle size input field below it. (3) When the analysis/volume statistical value (arithmetic mean) screen is displayed, the numerical value in the “>10 μm” display portion is the volume % of particles of 10.0 μm or more in the toner.

<Powder X-ray diffraction analysis>
An XRD pattern was measured using an X-ray diffraction analyzer (X'pert PRO-MPD: manufactured by PANalytical).
X-rays were generated at an acceleration voltage of 45 kV and a current of 40 mA.
The measurement conditions for powder X-rays are
Divergence slit: 1/4 rad (fixed)
Scattering prevention slit: 1/2 rad
Solar slit: 0.04rad
Mask: 15mm
Anti-scatter slit: 7.5mm
Spinner: Available Measurement method Scan axis: Continuous 2θ/θ
Measurement range: 5.0° ≤ 2θ ≤ 80°
Step interval: 0.026deg/s
Scanning speed: 0.525deg/s
was measured.
The sample used for measuring P70 has the same formulation as the porous ferrite core material, and an external magnetic field of 5000/4π (kA/m) is applied by changing the oxygen concentration in the firing process during manufacturing. Particles adjusted to have a magnetization strength of 70 Am ² /kg are used.

<Method for measuring strength of magnetization of magnetic core>
The strength of magnetization of the magnetic core can be determined by a vibrating magnetic field type magnetic property measuring device (Vibrating sample magnetometer) or a DC magnetic property recording device (BH tracer). In the examples described later, measurements are carried out using an oscillating magnetic field type magnetic property measuring apparatus BHV-30 (manufactured by Riken Denshi Co., Ltd.) according to the following procedure.
The sample is a cylindrical plastic container filled with sufficiently dense magnetic cores. Measure the actual mass of the sample filled in the container. After that, the sample in the plastic container is adhered with an instant adhesive so that the sample does not move.
A standard sample is used to calibrate the external magnetic field axis and magnetization moment axis at 5000/4π (kA/m).
The intensity of magnetization was measured from a loop of magnetization moment applied with an external magnetic field of 5000/4π (kA/m) at a sweep speed of 5 (min/roop). From these, the strength of magnetization of the magnetic core (Am ² /kg) is obtained by dividing by the weight of the sample.

<Toner manufacturing method>
A method for producing toner particles is not particularly limited, but a pulverization method is preferable from the viewpoint of dispersing a releasing agent or a polymer obtained by graft polymerization of a styrene-acrylic polymer to a polyolefin. The reason for this is that when toner particles are produced in an aqueous medium, highly hydrophobic release agents and polyolefin polymers grafted with styrene-acrylic polymers (styrene-acrylic resins) are localized inside the toner particles. tend to become Therefore, it becomes difficult to form the core-shell structure by the heat treatment apparatus described above.

The procedure for manufacturing toner by the pulverization method will be described below.
In the raw material mixing step, predetermined amounts of other components such as a binder resin, a release agent, a colorant, a crystalline polyester, and, if necessary, a charge control agent are weighed and blended as materials constituting the toner particles. , to mix. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechanohybrid (manufactured by Nippon Coke Kogyo Co., Ltd.).

Next, the mixed materials are melt-kneaded to disperse wax and the like in the binder resin. In the melt-kneading process, a batch-type kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used, and single-screw or twin-screw extruders have become mainstream due to their superiority in continuous production. ing. For example, KTK type twin-screw extruder (manufactured by Kobe Steel, Ltd.), TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM kneader (manufactured by Ikegai Iron Works), twin-screw extruder (manufactured by K.C.K. ), Co-Kneader (manufactured by Buss Co., Ltd.), Kneedex (manufactured by Nippon Coke Industry Co., Ltd.), and the like. Furthermore, the resin composition obtained by melt-kneading may be rolled with two rolls or the like and cooled with water or the like in the cooling step.

The cooled resin composition is then pulverized to a desired particle size in a pulverization step. In the pulverization step, for example, after coarse pulverization with a pulverizer such as a crusher, hammer mill, or feather mill, further, for example, Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.) or a fine pulverizer using an air jet method.

After that, classification such as inertial classification Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), centrifugal force classification system Turboplex (manufactured by Hosokawa Micron Corporation), TSP Separator (manufactured by Hosokawa Micron Corporation), Faculty (manufactured by Hosokawa Micron Corporation), etc. Classify using a sifter or sieving machine.

Thereafter, the toner particles are surface-treated by heating to increase the circularity of the toner. For example, the surface treatment apparatus shown in FIG. 1 can be used to perform surface treatment with hot air.
The mixture supplied by the raw material fixed quantity supply means 101 is guided to the introduction pipe 103 installed on the vertical line of the raw material supply means by the compressed gas adjusted by the compressed gas adjustment means 102 . The mixture that has passed through the introduction pipe is uniformly dispersed by a conical protruding member 104 provided in the central portion of the raw material supply means, and is led to a supply pipe 105 extending radially in eight directions, where heat treatment is performed in a processing chamber 106. led to.
At this time, the flow of the mixture supplied to the processing chamber is regulated by regulation means 109 provided in the processing chamber for regulating the flow of the mixture. Therefore, the mixture supplied to the processing chamber is heat-treated while swirling in the processing chamber, and then cooled.

Hot air for heat-treating the supplied mixture is supplied from the hot air supply means 107, and is helically swirled and introduced into the processing chamber by a swirling member 113 for swirling the hot air. As for the configuration, the swirling member 113 for swirling the hot air has a plurality of blades, and the swirling of the hot air can be controlled by the number and angle of the blades. The hot air supplied into the processing chamber preferably has a temperature of 100° C. to 300° C. at the outlet of the hot air supplying means 107 . If the temperature at the outlet of the hot air supply means is within the above range, it is possible to uniformly spheroidize the toner particles while preventing fusion and coalescence of the toner particles due to excessive heating of the mixture. Become.

Further, the heat-treated toner particles that have undergone heat treatment are cooled by cool air supplied from cold air supply means 108-1, 108-2, and 108-3, and the temperature is preferably -20°C to 30°C. If the temperature of the cold air is within the above range, the heat-treated toner particles can be efficiently cooled, and fusion and coalescence of the heat-treated toner particles can be prevented without impeding the uniform spheroidizing treatment of the mixture. be able to. The absolute water content of the cool air is preferably 0.5 g/m ³ or more and 15.0 g/m ³ or less.

The cooled, heat-treated toner particles are then collected by collection means 110 at the lower end of the processing chamber. A blower (not shown) is provided at the end of the recovering means, so that the particles are sucked and conveyed.
The powder particle supply port 114 is provided so that the swirling direction of the supplied mixture and the swirling direction of the hot air are the same. It is provided on the outer periphery of the processing chamber so as to maintain the turning direction. Furthermore, the cold air supplied from the cold air supply means 8 is configured to be supplied horizontally and tangentially from the outer peripheral portion of the apparatus to the inner peripheral surface of the processing chamber. The swirling direction of the toner supplied from the powder supply port, the swirling direction of the cool air supplied from the cool air supplying means, and the swirling direction of the hot air supplied from the hot air supplying means are all the same direction. As a result, turbulence does not occur in the processing chamber, the swirling flow in the device is strengthened, and a strong centrifugal force is applied to the toner, which further improves the dispersibility of the toner. can be obtained.

When the average circularity of the toner is 0.960 or more and 0.980 or less, the non-electrostatic adhesion force can be kept low, which is preferable from the viewpoint of fog resistance.

After that, it is divided into two parts, one on the fine side and the other on the coarse side. For example, it is divided into two using an inertial classification type elbow jet (manufactured by Nittetsu Mining Co., Ltd.). A desired amount of fine silica particles A is externally added to the surface of each of the bisected heat-treated toner particles. As a method for external addition treatment, a mixing device such as a double-con mixer, V-type mixer, drum-type mixer, super mixer, Henschel mixer, Nauta mixer, Mechanohybrid (manufactured by Nippon Coke Industry Co., Ltd.), Nobilta (manufactured by Hosokawa Micron Co., Ltd.), etc. is used as an external addition device to stir and mix. At that time, if necessary, an external additive other than silica fine particles, such as a fluidizing agent, may be externally added.
Methods for measuring various physical properties of toner and raw materials are described below.

<Production example of porous magnetic core particles>
Step 1 (weighing/mixing step)
_{Fe2O3 61.7} % by mass
_MnCO3 34.2% by mass
Mg(OH) ₂ 3.0% by mass
_SrCO3 1.1% by mass
The ferrite raw material was weighed so that
After that, it was pulverized and mixed for 2 hours in a dry ball mill using zirconia (φ10 mm) balls.

Step 2 (temporary firing step)
After pulverizing and mixing, the mixture was fired in air at 950° C. for 2 hours using a burner-type firing furnace to prepare calcined ferrite. The composition of ferrite is as follows.
(MnO)a(MgO)b(SrO) _c ( _Fe2O3 )d
In the above formula, a=0.40, b=0.07, c=0.01 and d=0.52.

Step 3 (crushing step)
After crushing the produced calcined ferrite to about 0.5 mm with a crusher, add 30 parts by weight of water to 100 parts by weight of calcined ferrite using zirconia balls (φ 1.0 mm), and crush with a wet ball mill for 2 hours. did. After the balls were separated, they were pulverized for 3 hours in a wet bead mill using zirconia beads (φ1.0 mm) to obtain a ferrite slurry.

Step 4 (granulation step)
To the ferrite slurry, 2.0 parts by mass of polyvinyl alcohol was added as a binder to 100 parts by mass of calcined ferrite, and the mixture was granulated into spherical particles of 40 μm with a spray dryer (manufacturer: Ogawara Kakoki).

Step 5 (main firing step)
In order to control the firing atmosphere, the spherical particles were fired at 1150° C. for 4 hours in a nitrogen atmosphere (oxygen concentration 1.0% by volume) in an electric furnace.

Step 6 (sorting step)
After the agglomerated particles were pulverized, the particles were sieved with a sieve having an opening of 250 μm to remove coarse particles, thereby obtaining porous magnetic core particles. This is called magnetic core 1 . Table 1 shows the physical properties of the magnetic core 1 thus obtained.

Step 7 (resin filling step)
100.0 parts by mass of the magnetic core 1 was placed in a stirring vessel of a mixing stirrer (universal stirrer NDMV type manufactured by Dalton), and nitrogen was introduced while maintaining the temperature at 60°C and reducing the pressure to 2.3 kPa. , the silicone resin solution was added dropwise to the magnetic core 1 so that the resin component was 7.5 parts by mass under reduced pressure, and the stirring was continued for 2 hours after the dropwise addition. Thereafter, the temperature was raised to 70° C., the solvent was removed under reduced pressure, and the particles of the magnetic core 1 were filled with the silicone resin composition obtained from the silicone resin solution. After cooling, the obtained packed magnetic core particles were placed in a rotatable mixing vessel and transferred to a mixer with spiral blades (Drum Mixer UD-AT manufactured by Sugiyama Heavy Industries Co., Ltd.), and heated to 2 (°C) under nitrogen atmosphere and normal pressure. /min), the temperature was raised to 220°C. Heating and stirring were performed at this temperature for 60 minutes to cure the resin. After the heat treatment, magnetic cores 2 were obtained by sorting low-magnetic products by magnetic separation and classifying them with a sieve having an opening of 150 μm. Table 1 shows the physical properties of the obtained magnetic core 2 .

<Production example of ferrite core particles>
Step 1 (weighing/mixing step)
_{Fe2O3 61.7} % by mass
_MnCO3 34.2% by mass
Mg(OH) ₂ 3.0% by mass
_SrCO3 1.1% by mass
The ferrite raw material was weighed so that
After that, it was pulverized and mixed for 2 hours in a dry ball mill using zirconia (φ10 mm) balls.

Step 2 (temporary firing step)
After pulverizing and mixing, the powder was fired in the atmosphere at 1000° C. for 2 hours using a burner type firing furnace to prepare calcined ferrite. The composition of ferrite is as follows.
(MnO)a(MgO)b(SrO) _c ( _Fe2O3 )d
In the above formula, a=0.40, b=0.07, c=0.01 and d=0.52.

Step 3 (crushing step)
After pulverizing the produced calcined ferrite to about 0.5 mm with a crusher, 30 parts by mass of water was added to 100 parts by mass of calcined ferrite using stainless balls (φ 1.0 mm), and pulverized for 2 hours with a wet ball mill. . After the balls were separated, they were pulverized in a wet bead mill for 3 hours using stainless balls (φ1.0 mm) to obtain a ferrite slurry.

Step 4 (granulation step)
To the ferrite slurry, 2.0 parts by mass of polyvinyl alcohol was added as a binder to 100 parts by mass of calcined ferrite, and the mixture was granulated into spherical particles of 45 μm with a spray dryer (manufacturer: Ogawara Kakoki).

Step 5 (main firing step)
In order to control the firing atmosphere, the spherical particles were fired at 1200° C. for 6 hours in a nitrogen atmosphere (oxygen concentration 0.6% by volume) in an electric furnace.

Step 6 (sorting step)
After the agglomerated particles were pulverized, the particles were sieved with a sieve having an opening of 250 μm to remove coarse particles to obtain ferrite core particles. This is called magnetic core 3 . Table 1 shows the physical properties of the obtained magnetic core 3 .

<Production example of magnetic material-dispersed resin core particles>
Magnetite fine particles (spherical, number average particle size 250 nm, saturation magnetization 50 (Am ² /kg), residual magnetization 4.2 (Am ² /kg), coercive force 4.4 (kA/m), 1000 (V/cm) specific resistance at 3.3×10 ⁶ (Ω cm)) and a silane-based coupling agent (3-(2-aminoethylaminopropyl)trimethoxysilane) (3.0% by mass with respect to the mass of the magnetite fine particles) amount) was introduced into the container. Then, the magnetite fine particles were surface-treated by high-speed mixing and stirring at a temperature of 100° C. or higher in the container.
Phenol 10 parts by mass Formaldehyde solution (37% by mass formaldehyde aqueous solution) 16 parts by mass Surface-treated magnetite fine particles 84 parts by mass The above materials were introduced into a reactor and mixed well at a temperature of 40°C.
After that, the mixture was heated to 85° C. at an average heating rate of 3 (° C./min) while stirring, and 4 parts by mass of 28% by mass aqueous ammonia and 25 parts by mass of water were added to the reactor. The temperature was kept at 85° C., and the mixture was cured by polymerization reaction for 3 hours. The peripheral speed of the stirring blade at this time was set to 1.8 (m/sec).
After the polymerization reaction, the temperature was cooled to 30° C. and water was added. The precipitate obtained by removing the supernatant was washed with water and air-dried. The resulting air-dried product was dried at a temperature of 60° C. under reduced pressure (5 hPa or less) to obtain magnetic material-dispersed resin core particles. This is called magnetic core 4 .
Table 1 shows the physical properties of the obtained magnetic core 4 .

<Production Example of Resin A1>
95.2% by weight of a silicone-containing acrylic monomer corresponding to unit Y1 shown below and 4.8% by weight of a monomer corresponding to unit Y2 were added to a reflux condenser, a thermometer, a nitrogen suction tube, and a grind-type stirrer. was added to a four-necked flask with The structures of unit Y1 and unit Y2 are shown in Table 2.
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The resulting mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin A1 solution (solid content: 35% by mass). The l+m value of this solution calculated by gel permeation chromatography (GPC) was 70.

<Production Examples of Resins A2 to A26>
Resins A2 to Resins A2 to A26 was obtained.

<Method for preparing macromonomer>
Macromonomers used for Resin B can be synthesized, for example, by the following method.
The raw materials indicated below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
・ Methacrylic acid chloride ... 1.7% by mass
-Polymethyl methacrylate having a hydroxyl group at one end (Mw; about 5000): 98.3% by mass
Further, 100 parts by mass of THF and 1.0 part by mass of 4-tert-butylcatechol are added to 100 parts by mass of the above monomer mixture, heated to reflux for 5 hours under a nitrogen stream, and washed with sodium bicarbonate after completion of the reaction. to obtain a solution of methacrylic acid macromonomer.

<Method for producing resin B1>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
- Cyclohexyl methacrylate...74.5% by mass
・Methyl methacrylate: 0.5% by mass
・Methacrylic acid macromonomer: 25% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The resulting mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B1 solution (solid content: 35 mass %). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 57,000. SPb is 10.2.

<Method for producing resin B2>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
- Cyclohexyl methacrylate...74.5% by mass
・Methyl methacrylate: 25.5% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The resulting mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B2 solution (solid content: 35% by mass). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 68,000. SPb is 10.2.

<Method for producing resin B3>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
・Methyl methacrylate: 75% by mass
・Methacrylic acid macromonomer: 25% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The obtained mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B3 solution (solid content: 35 mass %). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 35,000. SPb is 9.9.

<Method for producing resin B4>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
・Cyclohexyl methacrylate: 30% by mass
・Methyl methacrylate: 45% by mass
・Methacrylic acid macromonomer: 25% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The obtained mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B4 solution (solid content: 35 mass %). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 36,000. SPb is 10.1.

<Method for producing resin B5>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
- Hexyl methacrylate: 100% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The resulting mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B5 solution (solid content: 35 mass %). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 48,000. SPb is 9.3.

<Method for producing resin B6>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
・ Methacrylic acid (2-hydroxyethyl) ... 35.4% by mass
・Methyl methacrylate ... 64.6% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the monomer mixture. The resulting mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B6 solution (solid content: 35 mass %). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 37,000. SPb is 11.4.

<Method for producing resin B7>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
・Polydimethylsiloxane (average degree of polymerization 55) 5.0 parts by mass ・Methyltrichlorosilane 25.0 parts by mass ・Water 40.0 parts by mass ・Methyl isobutyl ketone 30.0 parts by mass Among the above materials, water, methyl isobutyl ketone was placed in a reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer, which had been stirred vigorously to prevent the formation of two layers, polydimethylsiloxane was added and further stirred and placed in an ice bath. When the temperature of the mixture in the reaction vessel reached 10°C, methyltrichlorosilane was added dropwise. After completion of dropping and washing, the solvent was distilled off under reduced pressure to obtain Resin B7. SPb is 10.2.

<Method for producing resin B8>
The monomers shown below were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
- Hexyl methacrylate: 10.0% by mass
・ Norbornene ... 90.0% by mass
Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2 parts by mass of bis(dibenzylideneacetone)palladium were added to 106 parts by mass of the above monomer mixture. The resulting mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a resin B8 solution (solid content: 35 mass %). The weight average molecular weight of this solution determined by gel permeation chromatography (GPC) was 37,000. SPb is 12.0.

<Resin coating process>
・ Method for producing magnetic carrier 1 Using the magnetic core 1 shown in Table 1, a planetary motion mixer (Nauta mixer VN type manufactured by Hosokawa Micron Corporation) maintained at a temperature of 60 ° C. under reduced pressure (1.5 kPa). A resin solution containing resin A and resin B shown in Table 3 was added so that the solid content of the resin component was 2.0 parts by mass with respect to 100 parts by mass of the magnetic core. As for the charging method, 1/3 of the amount of the resin solution was charged, and the solvent removal and coating operations were performed for 20 minutes. Next, 1/3 of the resin solution was added and the solvent was removed and applied for 20 minutes, and 1/3 of the resin solution was added and the solvent was removed and applied for 20 minutes.
After that, the magnetic carrier coated with the coating resin composition was placed in a rotatable mixing vessel and transferred to a mixer having spiral blades (Drum Mixer UD-AT manufactured by Sugiyama Heavy Industries, Ltd.). The mixture was heat-treated at a temperature of 120° C. for 2 hours under a nitrogen atmosphere while stirring by rotating the mixing vessel 10 times per minute. The obtained magnetic carrier 1 was subjected to magnetic separation to separate low magnetic products, passed through a sieve having an opening of 150 μm, and then classified by an air classifier. A magnetic carrier 1 having a 50% particle diameter (D50) of 39.1 μm based on volume distribution was obtained.
Table 3 shows the surface analysis results of the magnetic carrier 1 obtained.

Method for producing magnetic carriers 2 to 40 Magnetic carriers 2 to 40 were obtained by changing the resin A and resin B in the magnetic core and the coating resin solution to those shown in Table 3 in the method for producing magnetic carrier 1. . Physical properties are shown in Table 3.

<Production Example of Toner 1>
・Polyester resin 100 parts by mass ・Fischer-Tropsch wax (maximum endothermic peak peak temperature 90 ° C.) 4 parts by mass ・3,5-di-t-butylsalicylic acid aluminum compound (Bontron E88 manufactured by Orient Chemical Industry Co., Ltd.) 0.3 Parts by mass Carbon black 10 parts by mass After mixing the above materials using a Henschel mixer (FM-75 type, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 1500 rpm and a rotation time of 5 minutes, the temperature is set to 130 ° C. Biaxial The mixture was kneaded with a kneader (Model PCM-30, manufactured by Ikegai Co., Ltd.). The resulting kneaded product was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized product. The coarsely crushed product obtained was finely pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Further, classification was performed using Faculty (F-300, manufactured by Hosokawa Micron Corporation) to obtain toner base particles 1 . The operating conditions were a classification rotor rotation speed of 11000 rpm and a dispersion rotor rotation speed of 7200 rpm.

・Toner base particles 1 100 parts by mass ・Silica fine particles A (number average particle diameter (D1) is 120 nm) 2.0 parts by mass A Henschel mixer (FM-10C type, manufactured by Mitsui Mining Co., Ltd.) was mixed at a rotation speed of 1900 rpm for a rotation time of 3 minutes, heat treatment was performed by the surface treatment apparatus shown in FIG. The operating conditions were feed rate = 5 kg/hr, hot air temperature C = 160°C, hot air flow rate = 6 m ³ /min. , cold air temperature E=-5° C., cold air flow rate=4 m ³ /min. , blower air volume=20 m ³ /min. , injection air flow rate=1 m ³ /min. and
The obtained heat-treated toner particles 1 were adjusted so as to obtain uniform heat-treated toner particles 1 using an inertial classification type elbow jet (manufactured by Nittetsu Mining Co., Ltd.).
・Heat-treated toner particles 1 100 parts by mass ・Silica fine particles B (number average particle diameter (D1) is 20 nm) 0.6 parts by mass The above materials are rotated in a Henschel mixer (FM-75 model, manufactured by Mitsui Miike Kakoki Co., Ltd.). Mixing was carried out at 1900 rpm for a rotation time of 3 minutes to obtain Toner 1.

<Example 1>
To 91 parts by mass of magnetic carrier 1 was added 9 parts by mass of toner 1, and the mixture was shaken with a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) to prepare 300 g of two-component developer 1. The amplitude condition of the shaker was 150 rpm for 2 minutes.
On the other hand, 90 parts by mass of toner 1 was added to 10 parts by mass of magnetic carrier 1, and mixed for 5 minutes with a V-type mixer in an environment of normal temperature and humidity of 23° C. and 50% RH to obtain replenishing developer 1. rice field.

The two-component developer 1 and replenishment developer 1 were used for the following evaluations.
As an image forming apparatus, a Canon color copier imageRUNNER ADVANCE C5560 modified machine was used.
A two-component developer was put into each color developing device, a replenishing developer container containing a replenishing developer of each color was set, an image was formed, and various evaluations were made before and after the endurance test.
As a durability test, a chart of FFH output with an image ratio of 1% was used under a printing environment of temperature 23° C./humidity 5 RH% (hereinafter “N/L”). Also, under a printing environment of temperature 30° C./humidity 80 RH% (hereinafter “H/H”), an FFH output chart with an image ratio of 40% was used. FFH is a value representing 256 gradations in hexadecimal, 00h is the 1st gradation (white background portion) of 256 gradations, and FFH is the 256th gradation (solid portion) of 256 gradations. .
The number of image output sheets was changed according to each evaluation item.
conditions:
Paper: laser beam printer paper CS-814 (81.4 g/m ² )
(Canon Marketing Japan Inc.)
It was modified so that the image forming speed can be output at A4 size and full color at 80 (pages/min).
Development conditions: The development contrast can be adjusted at any value, and the automatic correction by the main unit has been modified so that it does not work. The peak-to-peak voltage (Vpp) of the alternating electric field was modified so that the frequency was 2.0 kHz and Vpp was changed from 0.7 kV to 1.8 kV in increments of 0.1 kV. Each color has been modified so that images can be output in a single color.

Each evaluation item is shown below.
(1) Image Density Under high temperature and high humidity environment (30° C., 80% RH), a solid image (FFH) was produced after evaluation of initial durability and durability image output (A4 landscape, 40% printing ratio, 50,000 sheets). output. Density was measured with a densitometer X-Rite 404A (manufactured by X-Rite), and the image density was obtained by averaging 6 points. The difference in image density at the initial stage of durability and after durability image output was judged according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: Density difference less than 0.10 B: Density difference 0.10 to less than 0.15 C: Density difference 0.15 to less than 0.20 D: Density difference 0.20 to 0.20 Less than 25 E: Density difference is 0.25 or more

(2) Fog After evaluation of image output (A4 landscape, 40% print ratio, 50,000 sheets) at the initial stage of durability and durability under a high-temperature and high-humidity environment (30°C, 80% RH), a solid white image on the entire surface of A4 was output. did. The fogging was evaluated by measuring the whiteness of the white background portion with a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.), calculating the fog concentration (%) from the difference in whiteness before and after the transfer, and evaluating it according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: Less than 1.0% B: 1.0% or more and less than 1.5% C: 1.5% or more and less than 2.0% D: 2.0% or more and less than 2.5% E: 2.5% or more

(3) Halftone developability Under high-temperature and high-humidity environment (30°C, 80% RH), the initial durability and durability image output evaluation (A4 landscape, 40% printing ratio, 50,000 sheets) was performed. 30H) was printed on an A4 sheet, and the area of 1000 dots was measured using a digital microscope VHX-500 (lens wide range zoom lens VH-Z100 manufactured by Keyence Corporation). The number average (S) of the dot area and the standard deviation (σ) of the dot area were calculated, and the dot reproducibility index was calculated by the following formula. Roughness of the halftone image was evaluated by the dot reproducibility index (I).
Dot reproducibility index (I) = σ/S x 100
Roughness was evaluated according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: I is less than 4.0 B: I is 4.0 or more and less than 5.0 C: I is 5.0 or more and less than 6.0 D: I is 7.0 or more and less than 8.0 E: I is 8.0 0 or more

(4) Toner scattering After evaluating the initial durability and durability image output (A4 landscape, 40% print ratio, 50,000 sheets) in a high-temperature and high-humidity environment (30°C, 80% RH), the developer was removed from the main unit. The developer was taken out, and the state of toner scattering inside and outside the developing device and the main body was visually observed and evaluated according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: No toner scattering B: Very slight toner scattering C: Slight toner scattering D: Toner scattering E: Significant toner scattering Table 5 shows the results obtained in the above evaluations (1) to (4) shown in

(Examples 2-33 and Comparative Examples 1-7)
Two-component developers 2 to 40 and replenishing developers 2 to 40 were prepared in the same manner as in Example 1, except that magnetic carriers 2 to 40 were used as shown in Table 4 instead of magnetic carrier 1 in Example 1. were prepared, and similar evaluations (1) to (4) were performed.
Table 5 shows the results obtained.

REFERENCE SIGNS LIST 1 electrostatic latent image carrier 2 charger 3 exposure device 4 developer 5 developer container 6 developer carrier 7 magnet 8 regulation member 11 transfer charger 12 recording medium (transfer material)
13 fixing device 15 cleaner 16 pre-exposure device

Claims (10)

A magnetic carrier having a magnetic core and a coating resin coating the surface of the magnetic core,
The coating resin contains resin A and resin B,
Based on the total mass of the coating resin, the content of the resin A is 1% by mass or more and 50% by mass or less, and the content of the resin B is 50% by mass or more and 99% or less,
The resin A has a unit Y1 represented by the following formula (1) and a unit Y2 represented by the following formula (2),
In the resin B, the content of the unit Y2 represented by the following formula (2) is 0.1% by mass or less,
When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, the X, the a, and the b are represented by the following formula. (a), (b)
0.90≦(a+b)/X≦1.00 (a)
1.00≤a/b≤30.0 (b)
The filling,
When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the Spa and the SPb are represented by the following formula (c)
0≦|SPa−SPb|≦2.0 (c)
A magnetic carrier characterized by satisfying
(In formula (1),
R ₁ represents H or CH ₃ ,
R ₂ represents a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, and the substituent is a hydroxy group or a carboxy group. )
(In formula (2),
R3 represents H or _{CH3 ,
R4} represents H or _CH3 ,
R ₅ represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms,
R ₆ represents a hydrocarbon group having 1 to 10 carbon atoms,
_R7 represents H, _CH3 or Si( _CH3 ) ₃ ,
n represents an integer of 2 or more and 150 or less. )

The resin B is characterized by containing 75% by mass or more of the unit Y1 represented by the formula (1),
The magnetic carrier according to claim 1. 3. The magnetic carrier according to claim 1, wherein n in the formula (2) is 5 or more and 60 or less. 4. The magnetic carrier according to claim 1, wherein the Si content of the surface of the magnetic carrier is 1.0 atomic % or more and 15.0 atomic % or less by ESCA analysis. 5. The apparatus according to any one of claims 1 to 4, wherein the following formula is satisfied, where m is the sum of the numbers of the units Y1 and Y2 represented by the formulas (1) and (2). magnetic carrier.
50≦m≦250 6. Any one of claims 1 to 5, wherein the coating resin contains 1% by mass or more and 20% by mass or less of resin A and 80% by mass or more and 99% by mass or less of resin B. The magnetic carrier according to . 7. Any one of claims 1 to 6, wherein the resin B has a unit Y3 represented by the following formula (3), and the content of the unit Y3 is 1% by mass or more and 75% by mass or less based on the resin B. 2. The magnetic carrier according to item 1.

( _In formula (3), R8 represents a cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclopentyl group, cyclobutyl group or cyclopropyl group.) 8. The magnetic carrier according to any one of claims 1 to 7, wherein the resin B contains a polymer obtained by graft polymerization of a styrene-acrylic resin to polypropylene. A two-component developer comprising the magnetic carrier according to any one of claims 1 to 8 and a toner. A replenishment developer containing the magnetic carrier according to any one of claims 1 to 8.

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