JP2022061925A - Magnetic carrier - Google Patents

Abstract

To provide a magnetic carrier capable of achieving image hue stability, preventing fog, and achieving a longer service life of developer, even when images are continuously outputted under conditions of low printing and fluctuations in environment.SOLUTION: A magnetic carrier includes a magnetic carrier core particle, and a resin coating layer formed on the surface of the magnetic carrier core particle. The resin coating layer of the magnetic carrier contains titanate compound particles with a perovskite structure. The titanate compound particles contain 500 to 5000 ppm of niobium atoms in terms of oxide.SELECTED DRAWING: None

Description

The present invention relates to a magnetic carrier used in an image forming method for visualizing an electrostatic charge image using electrophotographic methods.

Conventionally, in the electrophotographic image forming method, an electrostatic latent image is formed on an electrostatic latent image carrier by various means, and toner is adhered to the electrostatic latent image to form the electrostatic latent image. The method of developing is common. In this development, a two-component developing method is widely used in which carrier particles called magnetic carriers are mixed with toner, triboelectrically charged, an appropriate amount of positive or negative charge is applied to the toner, and the charge is developed as a driving force. It has been adopted.
Since the two-component developing method can impart functions such as stirring, transporting, and charging of the developer to the magnetic carrier, the division of functions with the toner is clear, and therefore, the controllability of the developer performance is good. There is.
On the other hand, due to technological advances in the field of electrophotographic photography, it is required to be able to output high-quality images at high speed and for a long period of time. In order to meet such demands, higher performance of magnetic carriers is required.
For example, various proposals have been made as carriers for improving high image quality and image quality stability (for example, Patent Documents 1 to 6). The carriers described in these documents are characterized by improving the structure of the coating resin and adding fine particles to the coating layer.

Japanese Unexamined Patent Publication No. 2012-173410 Japanese Unexamined Patent Publication No. 2012-066990 JP-A-2015-212777 JP-A-2017-122878 Japanese Unexamined Patent Publication No. 2008-0083938 Japanese Unexamined Patent Publication No. 2011-197569

The magnetic carrier described in the above patent document improves high image quality and image quality stability.
However, the usage of electrophotographic equipment is also diverse. For example, when the image density is low, or when printing is low such as characters and the output is continued under conditions where the environment fluctuates, the stability of the image is very high. It gets tougher. Similarly, even under such conditions, further improvement is required in order to improve high image quality and image quality stability.
An object of the present invention is to provide a magnetic carrier that solves the above problems. Specifically, it is an object of the present invention to provide a magnetic carrier capable of outputting a high-quality and highly stable image even when the output is low and the output is continuously performed under conditions where the environment fluctuates.

The present inventors use a magnetic carrier as shown below to stabilize the color of an image, suppress fog, and develop the image even when the output is continued under low printing conditions and conditions in which the environment fluctuates. It was found that the life of the agent can be extended at the same time.
That is, according to the present invention.
A magnetic carrier having a magnetic carrier core particles and a resin coating layer formed on the surface of the magnetic carrier core particles.
The magnetic carrier contains titanium acid compound particles having a perovskite structure in the resin coating layer.
The titanium acid compound particles are
Provided is a magnetic carrier having a niobium atom content of 500 ppm or more and 5000 ppm or less in terms of oxide.

According to the present invention, magnetism capable of achieving both color stability of an image, suppression of fog, and extension of the life of a developer even when printing is continued under low printing conditions and conditions in which the environment fluctuates. Can provide a carrier.

Sectional drawing which shows the schematic structure of the image forming apparatus Sectional drawing which shows the schematic structure of the full-color image forming apparatus

Hereinafter, embodiments for carrying out the present invention will be described in detail exemplary with reference to the drawings. However, the following description does not limit the scope of the present invention to the following embodiments.
In the following description, the description of "○○ or more and XX or less" and "○○ to XX" indicating a numerical range means a numerical range including a lower limit and an upper limit which are end points, unless otherwise specified.
"Monomer unit" refers to the reacted form of a monomeric substance in a polymer.
"(Meta) acrylic" means "acrylic" and / or "methacrylic".

The magnetic carrier according to the present invention is
A magnetic carrier having a magnetic carrier core particles and a resin coating layer formed on the surface of the magnetic carrier core particles.
The magnetic carrier contains titanium acid compound particles having a perovskite structure in the resin coating layer.
The titanium acid compound particles are
The content of niobium atom is 500 ppm or more and 5000 ppm or less in terms of oxide.
Conventionally, it has been known to add inorganic fine particles for strengthening the coating film of the coating film and adjusting the charging performance. Techniques such as adding a dielectric have also been proposed in order to further improve the developability. As a result, the effect of improving the developability was obtained, but it was found that the amount of toner flying to the non-image area also increased, which could cause fog. Therefore, the present inventors have diligently studied a method capable of simultaneously solving three problems such as coating film strengthening, developability, and fog.

As a result, the present inventors have found that the solution can be solved by incorporating titanium acid compound particles having a perovskite structure and containing a niobium atom in the carrier coating layer.
Although the details are not clear, by including the niobium atom in the titanic acid compound, the layers of the titanic acid compound are complemented, polycrystals oriented by the topochemical reaction are generated, the dielectric constant and the dielectric relaxation are changed, and the dielectric polarization is changed. Residue is effectively suppressed,
As a result, it is considered that the improvement of developability and the suppression of fog can be achieved at the same time, the strength of the coating film is improved due to the effect of the particles as a filler, and the deterioration of the carrier surface is suppressed.

Furthermore, it was found that by incorporating titanium acid compound particles having a perovskite structure and containing niobium atoms in the carrier coating layer, adhesion of toner-derived deposits to the carrier surface can be suppressed. Here, the toner-derived deposits indicate toner matrix particles and an external additive. The details of this are not clear, but it is thought that it is because the adhesion of electrostatic toner-derived deposits is suppressed by the dielectric polarization and the improvement of conductivity.

The magnetic carrier according to the present invention has a perovskite structure and contains titanium acid compound particles containing niobium atoms in the carrier coating layer. As a result, the magnetic carrier according to the present invention can suppress color fluctuation of an image even when low printing is continuously output under conditions where the environment fluctuates, and fog. Can also be suppressed.
Furthermore, probably because of the reduction of electrostatic adhesion, it is possible to suppress the adhesion derived from toner toner, and it is possible to maintain excellent color stability even when high printing is continuously output. ..

In the present invention, the content of niobium atom contained in the titanium acid compound particles is 500 ppm or more and 5000 ppm or less, preferably 700 ppm or more and 4500 ppm or less, and more preferably 1000 ppm or more and 4000 ppm or less. By containing niobium atoms within the above range, it is possible to maintain excellent color stability in both the case of continuous output of low printing and the case of continuous output of high printing.

As the titanate compound particles having a perovskite structure, BaTIO ₃ , SrTIO ₃ , CaTIO ₃ , CdTIO3, HgTIO ₃ , CaTIO ₃ , PbTIO ₃ , and the like are common, but SrTIO ₃ and CaTIO ₃ are preferable in the present invention. be. Further, CaTIO ₃ is particularly preferable. By using CaTiO ₃ , the property of the dielectric and the electric conductivity are well-balanced, and even when low printing is continuously output, excellent color stability can be maintained and fog can be reduced.

The major axis diameter or the number average particle diameter of the primary particles of the titanium acid compound particles having a perovskite structure is preferably 30 nm or more and 1000 nm or less, and more preferably 50 nm or more and 900 nm or less.
Further, when the major axis length is A and the minor axis length is B, the axial ratio A / B is preferably 1.2 to 3.0, more preferably 1.4 or more and 2.8 or less. By setting the axial ratio within the above range, the particles are easily fixed to the carrier, and the effect of the present invention can be maintained for a longer period of time.

The amount of the titanium acid compound particles having a perovskite structure added is preferably 5.0 parts by mass or more and 100.0 parts by mass or less, more preferably 10.0, with respect to 100 parts by mass of the coating resin of the resin coating layer. More than parts by mass and less than 90.0 parts by mass. By setting the addition amount within the above range, the effect of the present invention can be maintained for a long period of time.
The resin coating layer of the magnetic carrier of the present invention preferably contains a polymer of a monomer containing a (meth) acrylic acid ester having an alicyclic hydrocarbon group. Such a resin has a high effect of smoothing the coating film surface of the resin coated on the surface of the magnetic carrier core, suppressing the adhesion of toner-derived components, and suppressing the adhesion of toner-derived components.

Examples of the monomer containing a (meth) acrylic acid ester having an alicyclic hydrocarbon group include the following. Cyclobutyl acrylate, Cyclopentyl acrylate, Cyclohexyl acrylate, Cycloheptyl acrylate, Dicyclopentenyl acrylate, Dicyclopentanyl acrylate, Cyclobutyl methacrylate, Cyclopentyl methacrylate, Cyclohexyl methacrylate, Cycloheptyl methacrylate, Dimethacrylate Cyclopentenyl and dicyclopentanyl methacrylate. One kind or two or more kinds of these monomers may be selected and used.

Further, the resin coating layer is more preferably a copolymer resin of a (meth) acrylic acid ester monomer having an alicyclic hydrocarbon group and a macromonomer. By using the macromonomer, the transport stability of the developer is more effective, and the stability of the color tone is also improved.
The macromonomer is preferably a polymer of at least one monomer selected from the group consisting of the following monomers. Methyl acrylate, methyl methacrylate, butyl acrylate (n-butyl acrylate, sec-butyl acrylate, iso-butyl acrylate or tert-butyl acrylate), butyl acrylate, 2-ethylhexyl acrylate, 2 methacrylic acid -Ethylhexyl, styrene, acrylonitrile, and methacrylonitrile.

The weight average molecular weight (Mw) of the macromonomer is preferably 2000 or more and 10000 or less, and more preferably 3000 or more and 8000 or less.
The amount of the macromonomer used is preferably 5.0% by mass or more and 50.0% by mass or less, preferably 5.0% by mass or more and 40.0% by mass or less, based on all the monomers of the coating resin A. Is more preferable.

Next, the magnetic carrier core used in the present invention will be described.
As the magnetic carrier core used for the magnetic carrier, a known magnetic carrier core can be used. For example, in addition to the conventionally used magnetic carrier core, magnetic material-dispersed resin particles in which a magnetic material is dispersed in a resin component, or porous magnetic core particles containing a resin in a void portion can be used. ..

As the magnetic material component used for the magnetic material dispersion type resin particles, the following various magnetic iron compound particle powders can be used. Magnetite particle powder, magnetite particle powder, or magnetic iron oxide particle powder containing at least one selected from silicon oxide, silicon hydroxide, aluminum oxide and aluminum hydroxide; barium, Magnetite plumpite-type ferrite particle powder containing strontium or barium-strontium; spinel-type ferrite particle powder containing at least one selected from manganese, nickel, zinc, lithium and magnesium.
Among these, magnetic iron oxide particle powder can be preferably used.

Further, in addition to the magnetic material component, the following non-magnetic inorganic compound particle powder may be used in combination with the magnetic iron compound particle powder. Non-magnetic iron oxide particle powder such as hematite particle powder, non-magnetic hydroxide-containing ferric particle powder such as gateite particle powder. Titanium oxide particle powder, silica particle powder, talc particle powder, alumina particle powder, barium sulfate particle powder, barium carbonate particle powder, cadmium yellow particle powder, calcium carbonate particle powder, zinc flower particle powder, etc.
When the magnetic iron compound particle powder and the non-magnetic inorganic compound particle powder are mixed and used, the mixing ratio thereof is preferably at least 30% by mass of the magnetic iron compound particle powder.

It is preferable that all or part of the magnetic iron compound particle powder is treated with a lipophilic treatment agent.
As the oil-forming treatment agent used in that case, the following can be used. An organic compound having one or more functional groups selected from an epoxy group, an amino group, a mercapto group, an organic acid group, an ester group, a ketone group, an alkyl halide group and an aldehyde group, or a mixture thereof.
As the organic compound having a functional group, a coupling agent is preferable, a silane coupling agent, a titanium coupling agent and an aluminum coupling agent are more preferable, and a silane coupling agent is particularly preferable.

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

The content ratio of the binder resin constituting the magnetic material dispersed resin particles and the magnetic iron compound particle powder is preferably 1 to 20% by mass of the binder resin and 80 to 99% by mass of the magnetic iron compound particle powder.
The content ratio of the binder resin constituting the magnetic material dispersion type resin particles and the mixture of the magnetic iron compound particle powder and the non-magnetic inorganic compound particle powder is also 1 to 20% by mass of the binder resin and 80 to 99% by mass of the mixture. Is preferable.

Next, a method for producing the magnetically dispersed resin particles will be described.
The magnetic material-dispersed resin particles are prepared by, for example, in an aqueous medium containing phenols and aldehydes in the presence of magnetic and non-magnetic inorganic compound particle powders and a basic catalyst, as described in Examples described later. Stir. After that, there is a method of reacting and curing phenols and aldehydes to produce magnetic material dispersed resin particles containing inorganic compound particles such as magnetic iron oxide particle powder and phenol resin.
It can also be produced by a so-called kneading pulverization method or the like, in which a binder resin containing inorganic compound particles such as magnetic iron oxide particle powder is pulverized.
The former method is preferable in order to easily control the particle size of the magnetic carrier and obtain a sharp particle size distribution.

Next, a case where ferrite particles are used as the magnetic carrier core will be described.
The ferrite particles are preferably sintered ferrite represented by the following general formula.
(M1 ₂ O) x (M2O) y (Fe ₂ O ₃ ) z
(In the formula, M1 is a monovalent metal, M2 is a divalent metal, and when x + y + z = 1.0, x and y are 0 ≦ (x, y) ≦ 0.8, respectively. , Z is 0.2 <z <1.0)

In the formula, as M1 and M2, it is preferable to use at least one metal atom selected from the group consisting of Li, Fe, Mn, Mg, Sr, Cu, Zn, and Ca. In addition, Ni, Co, Ba, Y, V, Bi, In, Ta, Zr, B, Mo, Na, Sn, Ti, Cr, Al, Si, rare earths and the like can also be used. In particular, since the amount of magnetization can be maintained at an appropriate level and the rate of the ferrite formation reaction can be easily controlled, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr-based ferrite, and Li-Mn-based ferrite containing Mn atoms can be easily controlled. Is more preferable.

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

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

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

<Process 4 (granulation process)>
Water, a binder, and, if necessary, a pore modifier are added to the pulverized product of the calcined ferrite. Examples of the pore adjusting agent include a foaming agent and resin fine particles.
Examples of the foaming agent include sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, ammonium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, and ammonium carbonate.

Examples of the resin fine particles include the following fine particles. Polyester, polystyrene, styrene-vinyltoluene copolymer, styrene-vinylnaphthalin copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylate ester copolymer, styrene-α-chlormethylmethacrylate copolymer, Styrene copolymers such as styrene-acrylonitrile copolymers, styrene-vinylmethylketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, Select from phenolic resin, modified phenolic resin, malein resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin; aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohol and diphenol. Polyester resin having the monomer as a structural unit; polyurethane resin, polyamide resin, polyvinyl butyral, terpene resin, Kumaron inden resin, petroleum resin, hybrid resin having a polyester unit and a vinyl polymer unit.

As the binder, for example, polyvinyl alcohol is used.
In the case of wet pulverization in step 3, it is preferable to add a binder and a pore adjusting agent if necessary in consideration of the water contained in the ferrite slurry.
The obtained ferrite slurry is dried and granulated using a spray dryer, preferably in a warm atmosphere of 100 ° C. or higher and 200 ° C. or lower. The spray dryer is not particularly limited as long as the desired particle size of the porous magnetic core particles can be obtained. For example, a spray dryer can be used.

<Step 5 (main firing step)>
Next, the granulated product is baked at preferably 800 ° C. or higher and 1400 ° C. or lower, preferably 1 hour or longer and 24 hours or shorter.
By raising the calcination temperature and lengthening the calcination time, calcination proceeds, and as a result, the pore diameter is small and the number of pores is also reduced. By further raising the firing temperature and lengthening the firing time, ferrite particles without pores can be obtained.

<Process 6 (sorting process)>
After crushing the particles fired as described above, coarse particles and fine particles may be removed by classification or sieving with a sieve, if necessary.
From the viewpoint of excellent carrier adhesion to the image and suppression of roughness, the volume distribution standard 50% particle size (D50) of the magnetic core particles is preferably 18.0 μm or more and 68.0 μm or less.
In the following, when a porous magnetic core having pores is used in step 5, step 7 can be performed as needed.

<Step 7 (filling step)>
The physical strength of the porous magnetic core particles may be low depending on the internal pore volume, and in order to increase the physical strength as a magnetic carrier, at least a part of the voids of the porous magnetic core particles is made of resin. It is preferable to perform filling. The amount of the resin filled in the porous magnetic core particles is preferably 2% by mass or more and 15% by mass or less in the porous magnetic core particles.

If there is little variation in the resin content of each magnetic carrier, even if only a part of the internal voids is filled with the resin, the resin is filled only in the voids near the surface of the porous magnetic core particles and the voids remain inside. However, the internal voids may be completely filled with resin.
The method of filling the voids of the porous magnetic core particles with the resin is not particularly limited, but the porous magnetic core particles are made into a resin solution by a coating method such as a dipping method, a spray method, a brush coating method, and a fluidized bed. Examples thereof include a method of impregnating and then volatilizing the solvent. Further, a method of diluting the resin with a solvent and adding the resin to the voids of the porous magnetic core particles can also be adopted.

As the resin to be filled in the voids of the porous magnetic core particles, either a thermoplastic resin or a thermosetting resin may be used. It is preferable that it has a high affinity for porous magnetic core particles. When a resin having a high affinity is used, the surface of the porous magnetic core particles can be covered with the resin at the same time as filling the voids of the porous magnetic core particles with the resin.
Examples of the thermoplastic resin include the following. Novolac resin, saturated alkyl polyester resin, polyarylate, polyamide resin, acrylic resin, etc.
Further, examples of the thermosetting resin include the following. Phenolic resin, epoxy resin, unsaturated polyester resin, silicone resin, etc.

Further, the magnetic carrier has a resin coating layer on the surface of the magnetic carrier core.
The method of coating the surface of the magnetic carrier core with a resin is not particularly limited, and examples thereof include a method of coating by a dipping method, a spraying method, a brush coating method, a dry method, and a coating method such as a fluidized bed.

Further, the resin coating layer may contain particles having conductivity or particles or materials having charge controllability. Examples of the particles having conductivity include carbon black, magnetite, graphite, zinc oxide, and tin oxide.
The amount of the conductive particles added is preferably 0.1 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the coating resin in order to adjust the electric resistance of the magnetic carrier.

Examples of particles having charge controllability include the following. Organic metal complex particles, organic metal salt particles, chelate compound particles, monoazo metal complex particles, acetylacetone metal complex particles, hydroxycarboxylic acid metal complex particles, polycarboxylic acid metal complex particles, polyol metal complex particles. .. Polymethylmethacrylate resin particles, polystyrene resin particles, melamine resin particles, phenol resin particles, nylon resin particles, silica particles, titanium oxide particles, alumina particles, etc.
The amount of particles having charge controllability is preferably 0.5 parts by mass or more and 50.0 parts by mass or less with respect to 100 parts by mass of the coated resin in order to adjust the triboelectric charge amount.

Next, the composition of the preferable toner will be described in detail below.
The toner has a binder resin and, if necessary, toner particles containing a colorant and a mold release agent. Examples of the binder resin include vinyl resin, polyester resin, epoxy resin and the like. Among them, vinyl resin and polyester resin are more preferable because they can obtain excellent chargeability and fixability. Polyester resin is particularly preferable.

If necessary, the following may be mixed with the polyester resin and used. Monopolymers or copolymers of vinyl-based monomers, polyesters, polyurethanes, epoxy resins, polyvinyl butyral, rosins, modified rosins, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, etc.
When two or more kinds of resins are mixed and used as a binder resin, it is preferable to mix those having different molecular weights in an appropriate ratio as a more preferable form.
The glass transition temperature of the binder resin is preferably 45 ° C. or higher and 80 ° C. or lower, and more preferably 55 ° C. or higher and 70 ° C. or lower.
The number average molecular weight (Mn) is preferably 2500 or more and 50,000 or less. The weight average molecular weight (Mw) is preferably 10,000 or more and 1,000,000 or less.

As the binder resin, the polyester resin shown below is also preferable.
Based on all the monomer units constituting the polyester resin, it is preferable that 45 mol% or more and 55 mol% or less is an alcohol component, and 45 mol% or more and 55 mol% or less is an acid component.
The acid value of the polyester resin is preferably 0 mgKOH / g or more and 90 mgKOH / g or less, more preferably 5 mgKOH / g or more and 50 mgKOH / g or less, and the OH value is preferably 0 mgKOH / g or more and 50 mgKOH / g or less, more preferably 5 mgKOH / g. It is g or more and 30 mgKOH / g or less. This is because as the number of terminal groups of the molecular chain increases, the charging characteristics of the toner become more environmentally dependent.

The glass transition temperature of the polyester resin is preferably 50 ° C. or higher and 75 ° C. or lower, and more preferably 55 ° C. or higher and 65 ° C. or lower.
The number average molecular weight (Mn) is preferably 1500 or more and 50,000 or less, and more preferably 2000 or more and 20000 or less. The weight average molecular weight (Mw) is preferably 6000 or more and 100,000 or less, and more preferably 10,000 or more and 90000 or less.

The following crystalline polyester resin may be added to the toner for the purpose of promoting the plasticizing effect of the toner and improving the low temperature fixability.
Examples of the crystalline polyester include a polycondensate of a monomer composition containing an aliphatic diol having 2 or more and 22 or less carbon atoms and an aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms as main components.

The aliphatic diol having 2 or more and 22 or less carbon atoms (more preferably 6 or more and 12 or less carbon atoms) is not particularly limited, but is preferably a chain-like (more preferably linear) aliphatic diol. Among these, ethylene glycol, diethylene glycol, 1,4-butanediol, and linear aliphatics such as 1,6-hexanediol, α, ω-diol are preferably exemplified.
Of the alcohol components, 50% by mass or more is preferably selected from the aliphatic diol having 2 or more and 22 or less carbon atoms, and 70% by mass or more is more preferably selected from the aliphatic diol having 2 or more and 22 or less carbon atoms. preferable.

Polyhydric alcohol monomers other than aliphatic diols can also be used. Examples of the dihydric alcohol monomer include aromatic alcohols such as polyoxyethylene glycol A and polyoxypropylene glycol A; 1,4-cyclohexanedimethanol and the like.
Examples of the trihydric or higher polyhydric alcohol monomer include the following. Aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, 2-methyl Aliper alcohols such as propanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and trimethylolpropane.
Further, monovalent alcohol may be used to the extent that the characteristics of the crystalline polyester are not impaired.

On the other hand, the aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms (more preferably 6 or more and 12 or less carbon atoms) is not particularly limited, but is a chain-like (more preferably linear) aliphatic dicarboxylic acid. Is preferable. Hydrolyzed acid anhydrides or lower alkyl esters are also included.
Of the carboxylic acid components, 50% by mass or more is preferably selected from an aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms, and 70% by mass or more is selected from an aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms. Is more preferable.

A polyvalent carboxylic acid other than the aliphatic dicarboxylic acid having 2 or more and 22 or less carbon atoms can also be used. Examples of the divalent carboxylic acid include the following. Aromatic carboxylic acids such as isophthalic acid and terephthalic acid; aliphatic carboxylic acids of n-dodecylsuccinic acid and n-dodecenylsuccinic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. Acid anhydrides or lower alkyl esters of these carboxylic acids are also included.

Examples of the trivalent or higher polyvalent carboxylic acid include the following. Aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalentricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, pyromellitic acid; 1,2,4 -A aliphatic carboxylic acid such as butane tricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane. Derivatives such as acid anhydrides or lower alkyl esters of these carboxylic acids are also included.
Further, it may contain a monovalent carboxylic acid to the extent that the characteristics of the crystalline polyester are not impaired.

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

The toner may have a colorant. Examples of the colorant include the following.
Examples of the black colorant include those adjusted to black using carbon black; a yellow colorant, a magenta colorant, and a cyan colorant.

Examples of the coloring pigment for magenta toner include the following. Condensed azo compound, diketopyrrolopyrrole compound, anthracinone compound, quinacridone compound, basic dye lake compound, naphthol compound, benzimidazolone compound, thioindigo compound, perylene compound. Specifically, the following can be mentioned. 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, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221 238, 254, 269; C.I. I. Pigment Violet 19, C.I. I. Bat Red 1, 2, 10, 13, 15, 23, 29, 35.
The colorant may be a pigment alone, but it is preferable to use a dye and a pigment in combination to improve the sharpness of the colorant from the viewpoint of image quality of a full-color image.

Examples of the magenta toner dye include the following. C. I Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disperse thread 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27, C.I. I. Oil-soluble dyes such as Disper Violet 1, C.I. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, C.I. I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

Examples of the coloring pigment for cyan toner include the following. C. I. Pigment Blue 1, 2, 3, 7, 15: 2, 15: 3, 15: 4, 16, 17, 60, 62, 66; C.I. I. Bat Blue 6, C.I. I. Acid blue 45, a copper phthalocyanine pigment in which 1 to 5 phthalocyanine methyls are substituted in the phthalocyanine skeleton.

Examples of the yellow coloring pigment include the following. Condensed azo compound, isoindolinone compound, anthraquinone compound, azo metal compound, methine compound, allylamide compound. Specifically, the following can be mentioned. 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, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 155, 168, 174, 180, 181; 185, 191; C.I. I. Bat Yellow 1, 3, 20. In addition, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as Basic Green 6 and Solvent Yellow 162 can also be used.

The amount of the colorant used is preferably 0.1 part by mass or more and 30 parts by mass or less, more preferably 0.5 part by mass or more and 20 parts by mass or less, still more preferably, with respect to 100 parts by mass of the binder resin. It is 3 parts by mass or more and 15 parts by mass or less.
The method for producing the toner is not particularly limited, and a known method can be adopted. For example, a melt-kneading method, a suspension polymerization method, a dissolution-suspension method, an emulsification / aggregation method, and the like can be mentioned.

Further, in the above toner, it is preferable to use a binder resin mixed with a colorant in advance and made into a masterbatch. Then, by melt-kneading the colorant masterbatch and other raw materials (binding resin, wax, etc.), the colorant can be satisfactorily dispersed in the toner.
If necessary, a charge control agent can be used to further stabilize the chargeability of the toner. The charge control agent is preferably used in an amount of 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the binder resin. When it is 0.5 parts by mass or more, sufficient charging characteristics can be obtained. On the other hand, when it is 10 parts by mass or less, the compatibility with other materials becomes good, and excessive charging under low humidity can be suppressed.

Examples of the charge control agent include the following.
For example, an organometallic complex or a chelate compound is effective as a load electrical control agent for controlling the toner with load electrical properties. Examples thereof include monoazo metal complexes, aromatic hydroxycarboxylic acid metal complexes, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides thereof or esters thereof, and phenol derivatives of bisphenol.

Examples of the positive charge control agent for controlling the toner to positive charge include the following. Modified products such as niglocin and fatty acid metal salts, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and onium such as phosphonium salt which is an analog thereof. Salts and their chelating pigments include triphenylmethane dyes and their lake pigments (as lake agents, phosphotungstate, phosphomolybdic acid, phosphotungstate molybdenum, tannic acid, lauric acid, gallic acid, ferricyanic acid, As metal salts of higher fatty acids such as ferrussian compounds), diorganostin oxides such as dibutyltin oxide, dioctyltinoxide, and dicyclohexyltinoxide, and diorganosinborates such as dibutyltinborate, dioctyltinborate, and dicyclohexyltinborate.

If necessary, one kind or two or more kinds of mold release agents may be contained in the toner particles. Examples of the release agent include the following.
An aliphatic hydrocarbon wax such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax can be preferably used. In addition, oxides of aliphatic hydrocarbon waxes such as polyethylene oxide wax or block copolymers thereof; waxes containing fatty acid esters such as carnauba wax, sazole wax and montanic acid ester wax as main components; and Deoxidized fatty acid esters such as carnauba wax are partially or wholly deoxidized.
The amount of the release agent is preferably 0.1 part by mass or more and 20 parts by mass or less, and more preferably 0.5 part by mass or more and 10 parts by mass or less per 100 parts by mass of the binder resin.

Further, the melting point defined by the maximum endothermic peak temperature at the time of temperature rise measured by the differential scanning calorimeter (DSC) of the release agent is preferably 65 ° C. or higher and 130 ° C. or lower. More preferably, it is 80 ° C. or higher and 125 ° C. or lower. When the melting point is 65 ° C. or higher, the viscosity of the toner becomes suitable, so that the adhesion of the toner to the photoconductor can be suppressed. On the other hand, when the melting point is 130 ° C. or lower, the low temperature fixability is improved.

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

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

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

Further, in the image forming method, the developer has a two-component developer, and the replenishing developer is replenished to the developer according to the decrease in the toner concentration of the two-component developer in the developer. It may have such a configuration. The magnetic carrier of the present invention can be used as a replenishing developer for use in such an image forming method. The image forming method may have a configuration in which excess magnetic carriers in the developer are discharged from the developer as needed.
Further, the replenishing developer preferably contains a magnetic carrier, a binder resin, and a toner having toner particles containing a colorant and a mold release agent, if necessary. The replenishing developer preferably contains 2 parts by mass or more and 50 parts by mass or less of toner with respect to 1 part by mass of the replenishing magnetic carrier. The replenishing developer does not have a replenishing magnetic carrier and may be only toner.

Next, an image forming apparatus including a developing apparatus using a magnetic carrier, a two-component developer, and a supplementary developer will be described with reference to the present invention, but the present invention is not limited thereto.
<Image formation method>
In FIG. 1, the electrostatic latent image carrier 1 rotates in the direction of the arrow in the figure. The electrostatic latent image carrier 1 is charged by the charger 2 which is a charging means, and the surface of the charged electrostatic latent image carrier 1 is irradiated with exposure light by the exposure device 3 which is an electrostatic latent image forming means. , An electrostatic latent image is formed. The developer 4 has a developing container 5 for accommodating a two-component developer, the developer carrier 6 is arranged in a rotatable state, and a magnet 7 is used as a magnetic field generating means inside the developer carrier 6. Is included. At least one of the magnets 7 is installed so as to face the electrostatic latent image carrier 1.

The two-component developer is held on the developer carrier 6 by the magnetic field of the magnet 7, the amount of the two-component developer is regulated by the regulating member 8, and the development facing the electrostatic latent image carrier 1 is performed. It is transported to the department. In the developing unit, a magnetic brush is formed by the magnetic field generated by the magnet 7. After that, the electrostatic latent image is visualized as a toner image by applying a development bias formed by superimposing an alternating electric field on the DC electric field. The toner image formed on the electrostatic latent image carrier 1 is electrostatically transferred to the recording medium 12 by the transfer charger 11.

Here, as shown in FIG. 2, the electrostatic latent image carrier 1 may be temporarily transferred to the intermediate transfer body 9, and then electrostatically transferred to the transfer material (recording medium) 12. After that, the recording medium 12 is conveyed to the fixing device 13, where the toner is fixed on the recording medium 12 by heating and pressurizing. After that, the recording medium 12 is discharged to the outside of the device as an output image. After the transfer step, the toner remaining on the electrostatic latent image carrier 1 is removed by the cleaner 15.
After that, the electrostatic latent image carrier 1 cleaned by the cleaner 15 is electrically initialized by light irradiation from the pre-exposure 16, and the image forming operation is repeated.

FIG. 2 shows an example of a full-color image forming apparatus.
The arrows indicating the arrangement and rotation direction of the image forming units such as K, Y, C, and M in the drawing are not limited thereto. By the way, K means black, Y means yellow, C means cyan, and M means magenta. In FIG. 2, the electrostatic latent image carriers 1K, 1Y, 1C, and 1M rotate in the direction of the arrow in the figure. Each electrostatic latent image carrier is charged by the charging means 2K, 2Y, 2C, and 2M, and the surface of each charged electrostatic latent image carrier is exposed to the electrostatic latent image forming means 3K. The exposure light is irradiated by 3Y, 3C, and 3M to form an electrostatic latent image.

After that, the electrostatic latent image can be used as a toner image by the two-component developer supported on the developer carriers 6K, 6Y, 6C, and 6M provided on the developing units 4K, 4Y, 4C, and 4M, which are the developing means. It is visualized. Further, the toner image is transferred to the intermediate transfer body 9 by the intermediate transfer chargers 10K, 10Y, 10C, and 10M which are transfer means. Further, the toner image is transferred to the recording medium 12 by the transfer charger 11 which is a transfer means, and the recording medium 12 is heated and pressure-fixed by the fixing device 13 which is a fixing means and output as an image. Then, the intermediate transfer member cleaner 14, which is a cleaning member of the intermediate transfer body 9, collects the transfer residual toner and the like.

Specifically, as a developing method, an AC voltage is applied to the developer carrier to form an alternating electric field in the developing region, and a magnetic brush on the surface of the developer carrier is used as an electrostatic latent image carrier (photosensitive). It is preferable to perform development in contact with the body). The distance (distance between SD) between the developer carrier (development sleeve) 6 and the electrostatic latent image carrier (photosensitive drum) 1 is 100 μm or more and 1000 μm or less, which suppresses carrier adhesion and reproducible dots. Good for improvement. When the distance between SD and D is 100 μm or more, the developer is sufficiently supplied and the image density becomes good. When the distance between SD and D is 1000 μm or less, the magnetic force lines from the magnetic pole S1 are less likely to spread, the density of the magnetic brush becomes good, and the dot reproducibility is improved. In addition, the force that restrains the magnetic carrier is increased, and carrier adhesion can be suppressed.

The voltage (Vpp) between the peaks of the alternating electric field is preferably 300 V or more and 3000 V or less, and more preferably 500 V or more and 1800 V or less. The frequency is preferably 500 Hz or more and 10000 Hz or less, more preferably 1000 Hz or more and 7000 Hz or less, and each of them can be appropriately selected and used depending on the process.
In this case, examples of the AC bias waveform for forming the alternating electric field include a triangular wave, a square wave, a sine wave, and a waveform in which the duty ratio is changed. Occasionally, in order to respond to changes in the formation rate of the toner image, it is preferable to apply a development bias voltage (intermittent alternating superimposition voltage) having a discontinuous AC bias voltage to the developer carrier for development. .. When the applied voltage is 300 V or more, sufficient image density can be easily obtained, and fog toner in the non-image portion can be easily collected. Further, when the voltage is 3000 V or less, the latent image is less likely to be disturbed through the magnetic brush, and good image quality can be obtained.

By using a two-component developer having a well-charged toner, the fog removal voltage (Vback) can be lowered, and the primary charge of the photoconductor can be lowered, so that the life of the photoconductor is extended. can. The Vback is preferably 200 V or less, more preferably 150 V or less, although it depends on the developing system. As the contrast potential, 100 V or more and 400 V or less are preferably used so as to obtain a sufficient image density.

Further, when the frequency is lower than 500 Hz, the configuration of the electrostatic latent image carrier is usually the same as that of the photoconductor used in the image forming apparatus, although it is related to the process speed. For example, a photoconductor having a structure in which a conductive layer, an undercoat layer, a charge generation layer, a charge transport layer, and a charge injection layer, if necessary, are sequentially provided on a conductive substrate such as aluminum or SUS can be mentioned.
The conductive layer, the undercoat layer, the charge generation layer, and the charge transport layer may be those usually used for a photoconductor. As the outermost surface layer of the photoconductor, for example, a charge injection layer or a protective layer may be used.

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

<Measuring method of weight average particle size (D4) and number average particle size (D1)>
The weight average particle size (D4) and the number average particle size (D1) of the toner were calculated using the following precision particle size distribution measuring device and the following dedicated software.
-Precision particle size distribution measuring device: Precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter) equipped with a 100 μm aperture tube by the pore electrical resistance method.
-Dedicated software: Dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting measurement conditions and analyzing measurement data.
The measurement was performed with 25,000 effective measurement channels, and the measurement data was analyzed and calculated.
As the electrolytic aqueous solution used for the measurement, one in which special grade sodium chloride is dissolved in ion-exchanged water so that the concentration becomes about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter) can be used.

Before measuring and analyzing, the dedicated software was set as follows.
In the dedicated software "Change standard measurement method (SOM) screen", set the total count number in the control mode to 50,000 particles, measure once, and set the Kd value to "standard particles 10.0 μm" (Beckman Coulter). The value obtained by using (manufactured by) is set. By pressing the threshold / noise level measurement button, the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, and the electrolyte to ISOTON II, and check the flash of the aperture tube after measurement.
In the dedicated software "Pulse to particle size conversion setting screen", set the bin spacing to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.
The specific measurement method is as follows.

(1) Put about 200 mL of the electrolytic aqueous solution in a glass 250 mL round bottom beaker dedicated to Multisizer 3, set it on a sample stand, and stir the stirrer rod counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "flash of the aperture tube" function of the dedicated software.
(2) Put about 30 mL of the electrolytic aqueous solution in a 100 mL flat-bottomed beaker made of glass. To this, add about 0.3 mL of a diluted solution of the following "Contaminone N" as a dispersant diluted 3 times by mass with ion-exchanged water.
-Contaminone N: 10% by mass aqueous solution of a neutral detergent for cleaning a precision measuring instrument with a pH of 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.

(3) Two oscillators with an oscillation frequency of 50 kHz are built in with their phases shifted by 180 degrees, and a predetermined amount of ion-exchanged water is placed in the water tank of the following ultrasonic disperser having an electrical output of 120 W. About 2 mL of the contaminantinon N is added to this water tank.
-Ultrasonic disperser: Ultrasonic Dispersion System Tetora150, manufactured by Nikkaki Bios Co., Ltd. (4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic solution in the beaker is maximized.

(5) With the electrolytic aqueous solution in the beaker of (4) being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion processing is continued for another 60 seconds. For ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10 ° C. or higher and 40 ° C. or lower.
(6) Using a pipette, the electrolytic aqueous solution of (5) in which toner is dispersed is dropped onto the round bottom beaker of (1) installed in the sample stand, and the measured concentration is adjusted to about 5%. .. Then, the measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the device, and the weight average particle size (D4) and the number average particle size (D1) are calculated. The "average diameter" of the analysis / volume statistical value (arithmetic mean) screen when the graph / volume% is set by the dedicated software is the weight average particle diameter (D4). Further, the "average diameter" of the analysis / number statistical value (arithmetic mean) screen when the graph / number% is set by the dedicated software is the number average particle size (D1).

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

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

<Measurement of weight average molecular weight Mw of coating resin>
As a method of separating the resin coating layer from the magnetic carrier, there is a method of taking the magnetic carrier in a cup and eluting the coating resin with toluene.
After the eluted resin is dried to dryness, it is dissolved in tetrahydrofuran (THF) and measured using the following apparatus.
The sample (coating resin or coating resin separated from the magnetic carrier) and tetrahydrofuran (THF) are mixed at a concentration of 5 mg / mL and allowed to stand at room temperature for 24 hours to dissolve the sample in THF. After that, a sample that has passed through a sample processing filter (Misholidisk H-25-2 manufactured by Tosoh Corporation) is used as a GPC sample.
Next, using a GPC measuring device (HLC-8120GPC manufactured by Tosoh Corporation), measurement is performed under the following measurement conditions according to the operation manual of the device.

(Measurement condition)
Equipment: High-speed GPC "HLC8120 GPC" (manufactured by Tosoh Corporation)
Column: 7 stations of Shodex KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko KK)
Eluent: THF
Flow velocity: 1.0 mL / min
Oven temperature: 40.0 ° C
Sample injection volume: 0.10 mL
Further, in calculating the weight average molecular weight (Mw) and the peak molecular weight (Mp) of the sample, the calibration curve uses the molecular weight calibration curve prepared by the following standard polystyrene resin.
-Standard polystyrene resin: TSK standard polystyrene manufactured by Tosoh Co., Ltd. F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2 , F-1, A-5000, A-2500, A-1000, A-500

<Measurement method of elements in acid compound particles by fluorescent X-ray diffraction method>
For the measurement of the elements in the acid compound particles, after dissolving the resin coating layer of the magnetic carrier after coating with chloroform, only the acid compound particles are taken out by centrifugation or filtration, and dried ones can be used.
Elements from atomic number 11 Na to atomic number 92 U are directly measured in a He atmosphere using a wavelength dispersive fluorescent X-ray analyzer Axios advanced (manufactured by Spectris). Even if the resin component remains in the acid compound particles, since the element detected by the fluorescent X-ray analysis is a metal, information on only the acid compound particles can be obtained substantially.

For the acid compound particles, use the liquid sample cup attached to the device, put a PP (polypropylene) film on the bottom surface, put a sufficient amount (10 g) of the sample, form a uniform thick layer on the bottom surface, and cover it. The output is measured under the condition of 2.4 kW.
The FP (fundamental parameter) method is used for the analysis. At that time, it is assumed that all the detected elements are oxides, and their total mass is 100% by mass. The content (mass%) of each element with respect to the total mass is determined as an oxide conversion value by software UniQuant5 (ver. 5.49) (manufactured by Spectris).

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

<Production example of titanium acid compound particles 1 (calcium titanate particles)>
After deironing and bleaching 0.091 μm metatitanic acid obtained by the sulfuric acid method, a 4 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 9.0, and the desulfurization treatment was performed. Then, the pH was 5. It was neutralized to 5 and washed with filtered water.
Water was added to the washed cake to make a slurry of 1.25 mol / L as TiO ₂ , and then 6 mol / L hydrochloric acid was added to adjust the pH to 1.2 for deflocculation treatment. This glutinous slurry was neutralized to pH 6.5 by adding a 5 mol / L sodium hydroxide aqueous solution, and washed with filtered water.

Water is added to 0.726 mol of washed cake as TiO ₂ to form a slurry, which is then charged into a 2 L reaction vessel. Calcium hydroxide powder as a calcium source was added to this deflocculated / neutralized metatitanic acid slurry so that the CaO / TiO ₂ molar ratio was 1.02. Then, niobium pentachloride was added so as to have a TiO 2 molar ratio of 0.017 and mixed.
Then, the TiO2 concentration was adjusted to 0.752 mol / L. After adjusting the slurry pH to 12.5 by adding a sodium hydroxide solution having a pH of 10 mol / L, nitrogen gas was blown into the slurry and allowed to stand for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. Next, while flowing nitrogen through this reaction vessel, the mixed solution of metatitanic acid and calcium hydroxide was heated to 98 ° C. while further stirring and mixing, and the mixture was kept stirred for 6.5 hours.

When the reaction product is observed with a transmission electron microscope, it is a rectangular parallelepiped particle, and the average long side length seen from the side surface is 0.10 μm, the average short side length is 0.056 μm, and the axial ratio is 1. It was eight. After the reaction was completed, the slurry was filtered, washed and dried, and then pulverized using a hammer mill. X-ray diffraction identified a single phase of calcium titanate with a perovskite structure.

<Production example of titanium acid compound particles 2 to 16>
In the production example of the titanium acid compound particles 1, the selection of calcium or strontium, the amount of niobium atoms, and the length of the long side and the length of the short side were changed to obtain the titanium acid compound particles 2 to 16 shown in Table 1.

<Production examples of coating resins 1 and 2>
The raw materials shown in Table 2 (50 parts in total) were added to a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube and a ground-glass agitator. Further, 100.0 parts of toluene, 100.0 parts of methyl ethyl ketone, and 2.0 parts of azobisisovaleronitrile were added and kept at 80 ° C. under a nitrogen stream for 10 hours, and the coating resin 1 and 2 solutions (solid content 40% by mass) were added. Obtained.

In the table, the numerical value of each material indicates the number of copies. The abbreviations in the table are as follows.
CHMA: Cyclohexylmethacrylate MMA: Methylmethacrylate MAA: Methacrylic acid Macromonomer A is a methyl methacrylate polymer represented by the following formula (M), in which Z in the formula (M) is represented by the following structure (Z). The weight average molecular weight Mw of the macromonomer MMA is 5000.

<Manufacturing example of magnetic carrier core 1>
Process 1 (Weighing / mixing process)
Fe ₂ O ₃ 68.3% by mass
MnCO ₃ 28.5% by mass
Mg (OH) ₂ 2.0% by mass
SrCO ₃ 1.2% by mass
The above ferrite raw materials were weighed, 20 parts of water was added to 80 parts of the ferrite raw material, and then wet mixing was performed with a ball mill for 3 hours using zirconia having a diameter (φ) of 10 mm to prepare a slurry. The solid content concentration of the slurry was 80% by mass.

Step 2 (temporary firing step)
After drying the mixed slurry with a spray dryer (manufactured by Okawara Kakohki Co., Ltd.), it is calcined in a batch electric furnace under a nitrogen atmosphere (oxygen concentration 1.0% by volume) at a temperature of 1050 ° C. for 3.0 hours. Ferrite was prepared.
Process 3 (crushing process)
After crushing the calcined ferrite to about 0.5 mm with a crusher, water was added to prepare a slurry. The solid content concentration of the slurry was set to 70% by mass. The slurry was obtained by grinding with a wet ball mill using 1/8 inch stainless beads for 3 hours. Further, this slurry was pulverized with a wet bead mill using zirconia having a diameter of 1 mm for 4 hours to obtain a calcined ferrite slurry having a volume-based 50% particle diameter (D50) of 1.3 μm.

Process 4 (granulation process)
To 100 parts of the calcined ferrite slurry, 1.0 part of ammonium polycarboxylate as a dispersant and 1.5 parts of polyvinyl alcohol as a binder are added, and then granulated into spherical particles by a spray dryer (manufactured by Okawara Kakohki Co., Ltd.). , Dry. After adjusting the particle size of the obtained granulated product, it was heated at 700 ° C. for 2 hours using a rotary electric furnace to remove organic substances such as a dispersant and a binder.

Step 5 (firing step)
Under a nitrogen atmosphere (oxygen concentration 1.0% by volume), the time from room temperature to the firing temperature (1300 ° C.) was set to 2 hours, and the temperature was maintained at 1300 ° C. for 5 hours for firing. Then, the temperature was lowered to 60 ° C. over 8 hours, returned to the atmosphere from the nitrogen atmosphere, and taken out at a temperature of 40 ° C. or lower.
Process 6 (sorting process)
After crushing the agglomerated particles, coarse particles were removed by sieving with a sieve having a mesh size of 150 μm, fine particles were removed by wind power classification, and non-magnetic substances were removed using a magnetic dressing machine. Further, coarse particles were removed with a vibrating sieve to obtain a magnetic carrier core 1 having a D50 of 34 μm.

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

<Manufacturing examples of magnetic carriers 1 to 3, 5 to 13>
<Formation of resin coating layer>
The resin shown in Table 2 was diluted with toluene so that the resin component was 5%, and the titanium acid compound particles 1 were added so as to be 40.0 parts with respect to 100.0 parts of the resin solid content. The resin solution stirred in the above was prepared as the resin solution 1 for the resin coating layer.
After that, in the following planetary motion type mixer maintained at a temperature of 60 ° C., the resin liquid for the resin coating layer has an amount of the resin solid content of 2.3 parts with respect to 100.0 parts of the magnetic carrier core 1. 1 was added, and the solvent was removed and the coating operation was performed for 40 minutes.
・ Planetary motion type mixer: Nautamixer VN type manufactured by Hosokawa Micron Co., Ltd.

Then, the magnetic carrier coated with the resin coating layer is transferred to the following mixer having spiral blades in a rotatable mixing container, and the mixing container is rotated 10 times per minute to stir, and the temperature is 180 under a nitrogen atmosphere. Heat-treated at ° C for 2 hours.
・ Mixer: Drum mixer UD-AT type manufactured by Sugiyama Heavy Industries, Ltd. The obtained magnetic carrier is separated into low magnetic force products by magnetic force beneficiation, passed through a sieve with an opening of 150 μm, and then classified by a wind power classifier. I got 1.
As shown in Table 3, the same as the production example of the magnetic carrier 1 except that the core type, the resin type for the resin coating layer and the number of parts to be added, and the titanium acid compound particles shown in Table 1 and the number of parts to be added were changed. Magnetic carriers 2 to 3, 5 to 13 were obtained.

<Manufacturing examples of magnetic carriers 4, 15 and 16>
The amount of the following methyl silicone resin solution to be 1.8 parts with respect to 100.0 parts of the magnetic core and the titanium acid compound particles 4 to 100.0 parts with respect to the resin solid content. It was added so as to be 0 parts, and 25% by weight of titanium diisopropoxybis (ethylacetacetate) was added as a catalyst with respect to the resin solid content.
Methyl silicone resin solution: A resin solution concentration of 20% was diluted with toluene to 5%. Then, 10% by weight of 3-aminopropyltriethoxysisilane was added to the resin solid content as an aminosilane coupling agent, and 60 was added. Toluene was volatilized by mixing and stirring at ° C. under a reduced pressure of 6.7 kPa (about 50 mmHg).
Then, it was placed in a hot air heating type oven and heat-treated at 220 ° C. for 1.5 hours. The magnetic carrier obtained by cooling and crushing was separated into low magnetic force products by magnetic beneficiation, passed through a sieve having an opening of 150 μm, and then classified by a wind power classifier to obtain a magnetic carrier 4.
Magnetic carriers 15 and 16 were obtained in the same manner as in the production example of the magnetic carrier 4 except that the titanium acid compound particles shown in Table 1 and the number of copies thereof were changed.

<Manufacturing example of toner (magenta toner and cyan toner)>
The materials shown in Table 4 were well mixed with a Henschel mixer (FM-75J type, manufactured by Nippon Coke Industries Co., Ltd.). Then, it was kneaded with a twin-screw kneader (trade name: PCM-30 type, manufactured by Ikegai Steel Co., Ltd.) set to a temperature of 130 ° C. at a feed amount of 10 kg / hr (the temperature of the kneaded product at the time of discharge was 150 ° C.). .. The obtained kneaded product was cooled, coarsely crushed with a hammer mill, and then finely pulverized with a mechanical crusher (trade name: T-250, manufactured by Turbo Industries, Ltd.) at a feed amount of 10 kg / hr. Then, particles having a weight average particle diameter of 4.3 μm were obtained.

The monomer composition of the polyester resin is as follows.
42 parts of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane,
-Polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 8 parts,
・ 35 parts of terephthalic acid, 4 parts of trimellitic anhydride, 11 parts of fumaric acid

The obtained particles were classified by a rotary classifier (trade name: TTSP100, manufactured by Hosokawa Micron Co., Ltd.) to cut fine powder and coarse powder. Cyan has a weight average particle size of 5.0 μm, an abundance rate of particles having a particle size of 3.0 μm or less is 18.8% by volume, and an abundance rate of particles having a particle size of 10.0 μm or more is 0.3% by volume. Toner particles and magenta toner particles were obtained.

Further, the following materials are put into the following Henshell mixer and mixed under the following mixing conditions to adhere the silica particles and the titanium oxide particles to the surfaces of the cyan toner particles and the magenta toner particles, and the cyan toner and the magenta toner are adhered to the surface. Got
・ Henshell mixer: Brand name FM-75J type, manufactured by Nippon Coke Industries Co., Ltd. ・ Mixing conditions: Peripheral speed of rotating blades 35.0 m / sec, mixing time 3 minutes ・ Toner particles of each color: 100.0 parts ・ Silica particles: 3.0 parts (Silica particles prepared by the fumed method are surface-treated with 1.5% by mass of hexamethyldisilazane and then adjusted to the desired particle size distribution by classification).
-Titanium oxide particles: 1.7 parts (Anatase-type crystalline metatitanium acid surface-treated with an octylsilane compound)
-Strontium titanate particles: 0.5 part (surface treated with octylsilane compound)
Using the above cyan toner, magenta toner and magnetic carriers 1 to 16, shake each material with a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) so that the toner concentration becomes 7.0% by mass. Finally, 1 to 16, 300 g of a two-component developer was prepared. The amplitude condition of the shaker was 200 rpm for 2 minutes.

<Examples 1 to 12 and Comparative Examples 1 to 4>
The following evaluations were performed using the above-mentioned two-component developing agents 1 to 16.
The two-component developeres 1 to 16 were also used as a supplementary developer for each developer.
As an image forming apparatus, a Canon Inc. color copier imagePRESS C850 remodeling machine was used.
A two-component developer is put in each color developer, and a replenisher developer container filled with toner of each color is set as a developer for each color replenishment, an image is formed, and various evaluations are performed before and after the paper passing durability test. rice field.
The test environment is shown below.
-Temperature 23 ° C / relative humidity 50% (hereinafter "N / N")
-Temperature 23 ° C / relative humidity 5% (hereinafter "N / L")
-Temperature 30 ° C / relative humidity 80% (hereinafter "H / H")
When the durability was examined, a chart of FFH output in which the image area ratio was adjusted was used.
FFH is a value in which 256 gradations are displayed in hexadecimal, 00h is the first gradation (white background portion) of 256 gradations, and FFH is the 256th gradation (solid portion) of 256 gradations. ..

(conditions)
Paper: Laser Beam Printer Paper CS-814 (81.4g / m ² ) (Canon Marketing Japan Co., Ltd.)
Image formation speed: A4 size, full color 85 sheets / min
Development conditions: The development contrast can be adjusted by any value, and it has been modified so that the automatic correction by the main unit does not work. The voltage (Vpp) between the peaks of the alternating electric field was modified so that the frequency could be changed from 0.7 kV to 1.8 kV in increments of 0.1 kV at a frequency of 2.0 kHz.

Each evaluation item is shown below.
(1) Low printing and color change due to environmental changes (evaluation X)
In an N / N environment, a paper passing durability test of 10,000 sheets was performed using a chart with an FFH output having an image area ratio of 1.5%. Immediately after that, an FFH blue image having a size of 50 mm × 50 mm was output to the center of the paper on A4 size paper (CS-814). At this time, the development contrast of cyan and magenta was adjusted so that the amount of toner on the paper was 0.35 mg / cm ² for both cyan and magenta. The tint (a ^* , b ^* ) was measured using a SpectroScan Transition (manufactured by GretagMacbeth).
After that, the main body of the copying machine was moved to an N / L environment, and 24 hours after the movement, the FFH blue image having a size of 50 mm × 50 mm was output to the center of the paper, and the tint was measured.

The color measurement conditions are as follows.
<Measurement conditions>
Observation light source: D50
Observation field of view: 2 °
Concentration: DIN NB
White standard: Pap
Filter: None
In general, a ^* and b ^* are values used in the L ^* a ^* b ^* color system, which is a useful means for expressing colors numerically. a ^* and b ^* both represent hue. Hue is a scale of hue such as red, yellow, green, blue, and purple. Each of a ^* and b ^* indicates the color direction, a ^* indicates the red-green direction, and b ^* indicates the yellow-blue direction.

In addition, C ^* is called saturation, which represents a measure of color vividness and is expressed as follows.
C ^* = {(a ^* ) ² + (b ^* ) ² } ^1/2

C ^{* 2 is defined as C * 2} _immediately after the 20000 sheet durability test is performed on the FFH output chart with an image ratio of 5%, and C ^* ₁ immediately after 10 sheets are output on the FFH output chart with an image ratio of 40% ^. (C ^* ₁ -C ^* ₂ ) was set to ΔC ^* , and evaluation was performed according to the following evaluation criteria. The results are shown in Table 5.

A (10 points): 0.0≤ΔC ^* <0.5
B (9 points): 0.5≤ΔC ^* <1.0
C (8 points): 1.0 ≤ ΔC ^* <1.5
D (7 points): 1.5 ≤ ΔC ^* <2.0
E (6 points): 2.0 ≤ ΔC ^* <2.5
F (5 points): 2.5 ≤ ΔC ^* <3.0
G (4 points): 3.0 ≤ ΔC ^* <3.5
H (3 points): 3.5 ≤ ΔC ^* <4.0
I (2 points): 4.0 ≤ ΔC ^*

(2) Low printing and fog during environmental changes (evaluation Y)
Immediately after conducting a paper passing durability test of 10,000 sheets using an FFH output chart with an image area ratio of 1.5% in an N / N environment, the copier body was moved to the H / H environment and kept still in the same environment for 24 hours. I put it. After that, an image (00h image) having a white background portion was output using two colors of magenta and cyan.
The fog density (%) is calculated from the difference between the whiteness of the white background of the printout image measured by "REFLECTMER MODEL TC-6DS" (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the recording material, and the image fog is evaluated. bottom. A green light filter was used as the filter.

The judgment criteria are as follows.
A (10 points): Less than 0.8% B (9 points): 0.8% or more and less than 1.1% C (8 points): 1.1% or more and less than 1.4% D (7 points): 1 1.4% or more and less than 1.7% E (6 points): 1.7% or more and less than 2.0% F (5 points): 2.0% or more and less than 2.3% G (4 points): 2.3 % Or more and less than 2.6% H (3 points): 2.6% or more The results are shown in Table 5.

(3) High printing and color change due to environmental changes (evaluation Z)
A paper passing durability test of 20000 sheets was performed using a chart of FFH output having an image area ratio of 40% in an N / N environment. Immediately after that, an FFH blue image having a size of 50 mm × 50 mm was output to the center of the paper on A4 size paper (CS-814). At this time, the development contrast of cyan and magenta was adjusted so that the amount of toner on the paper was 0.35 mg / cm ² for both cyan and magenta. The tint (a ^* , b ^* ) was measured using a SpectroScan Transition (manufactured by Gretag Macbeth) in the same manner as in the evaluation X.
After that, the main body of the copying machine was moved to an H / H environment, and 24 hours after the movement, the FFH blue image having a size of 50 mm × 50 mm was output to the center of the paper, and the tint was measured.
The color measurement method and evaluation criteria were the same as those for evaluation X. The results are shown in Table 5.

1, 1K, 1Y, 1C, 1M: Electrostatic latent image carrier, 2, 2K, 2Y, 2C, 2M: Charger, 3, 3K, 3Y, 3C, 3M: Exposed device, 4, 4K, 4Y, 4C 4, 4M: developer, 5: developing container, 6, 6K, 6Y, 6C, 6M: developer carrier, 7: magnet, 8: regulatory member, 9: intermediate transfer body, 10K, 10Y, 10C, 10M: intermediate Transfer Charger, 11: Transfer Charger, 12: Transfer Material (Recording Medium), 13: Fixer, 14: Intermediate Transfer Cleaner, 15, 15K, 15Y, 15C, 15M: Cleaner, 16: Pre-Exposure

Claims (7)

A magnetic carrier having a magnetic carrier core particles and a resin coating layer formed on the surface of the magnetic carrier core particles.
The magnetic carrier contains titanium acid compound particles having a perovskite structure in the resin coating layer.
The titanium acid compound particles are
A magnetic carrier having a niobium atom content of 500 ppm or more and 5000 ppm or less in terms of oxide. The major axis diameter or the number average particle diameter of the primary particles of the titanium acid compound particles is
The magnetic carrier according to claim 1, wherein the magnetic carrier is 30 nm or more and 1000 nm or less. Claim 1 or 2 that the amount of the titanic acid compound particles added to the resin coating layer is 5.0 parts by mass or more and 100.0 parts by mass or less with respect to 100 parts by mass of the coating resin of the resin coating layer. The magnetic carrier described in. The magnetic carrier according to any one of claims 1 to 3, wherein the coating resin of the resin coating layer contains at least a polymer of a monomer containing a (meth) acrylic acid ester having an alicyclic hydrocarbon group. The coating resin of the resin coating layer contains at least a (meth) acrylic acid ester having an alicyclic hydrocarbon group and a copolymer of a macromonomer.
The macromonomer is one or more selected from methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, acrylonitrile, and methacrylonitrile. The magnetic carrier according to any one of claims 1 to 4, which is a polymer of the monomer of. The magnetic carrier according to any one of claims 1 to 5, wherein the titanate compound particles are calcium titanate particles or strontium titanate particles. The titanium acid compound particles have an axial ratio A / B of 1.2 to 3.0 when the major axis length is A and the minor axis length is B, according to any one of claims 1 to 6. The magnetic carrier described.

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