JP2001215757A - Magnetic particle dispersion type composite particle and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic particle dispersion type composite particles with which a toner image of high picture quality can be formed without deposition of particles while fog is prevented or suppressed. SOLUTION: In the magnetic particle dispersion type composite particles containing at least a binder resin and magnetic particles, the binder resin is prepared by the reaction of phenols and aldehydes in the presence of at least an amine-based catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to magnetic particle-dispersed composite particles used for electrophotography, electrostatic recording, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art U.S. Pat.
7, 691, JP-B-42-23910 and JP-B-43-24748 describe various methods. In each of these methods, an electrostatic latent image is formed by irradiating a photoconductive layer with a light image corresponding to a document, and then a toner called a toner having an opposite polarity is formed on the electrostatic latent image. The electrostatic latent image is developed by adhering fine powder, and if necessary, a toner image is transferred to a transfer material such as paper, and then fixed by heat, pressure, heating, pressurization, or solvent vapor to obtain a copy. What you get.

In the step of developing the electrostatic latent image, a toner image is formed on the charged toner particles by utilizing the electrostatic interaction of the electrostatic latent image. In general, of the methods for developing an electrostatic latent image using toner, a two-component developer in which toner is mixed with a carrier is suitably used for a full-color copying machine or a printer requiring particularly high image quality.

In recent years, the electrophotographic method has been widely used in copiers and printers, and is required to be able to handle various objects such as fine lines, small letters, photographs, and color originals. Further, higher image quality, higher quality, higher speed, and continuity are also required, and these requirements are expected to increase in the future.

Conventionally, iron powder carriers,
Ferrite carriers or binder type carriers (composite particles in which magnetic fine particles are dispersed in a resin) and the like have been developed and put into practical use.

The iron powder carrier has a flake shape, a sponge shape, and a spherical shape.
And the bulk density is as large as ³ to 4 g / cm ³ , so that a large driving force is required to stir the toner in the developing machine, there is a lot of mechanical wear, the toner becomes spent, and the carrier itself is removed. Deterioration of chargeability and damage to the photoconductor are likely to occur.

The ferrite carrier is spherical and has a specific gravity of 4.5.
Since it is about 5.5 and the bulk density is about 2 to ³ g / cm ³ , the weight which is a drawback of the iron powder carrier can be solved to some extent, but it is not enough.

[0008] The binder type carrier is 2.5 g / cm
^The bulk density is as small as about ³ or less, and the particles have less shape distortion, and the particle strength tends to be high. And the particle size thereof can be controlled in a wide range, so that it is most expected in a high-speed copying machine in which the number of rotations of a developing sleeve or a magnet in the sleeve is large, a high-speed laser beam printer of a general-purpose computer, and the like.

First, the carrier is required to have an appropriate saturation magnetization value, particularly a saturation magnetization value of about ^{20 to} 70 Am ² / kg. That is, a good image can be obtained by setting the value of the saturation magnetization of the carrier in the range of ²⁰ to 70 Am ² / kg. By setting the magnetization value to 20 Am ² / kg or more, the so-called “spike” of the magnet brush on the sleeve
Due to the low magnetic force, the carrier forming the particles is separated from the “ears” and flies to the photoconductor, so that the so-called carrier adhesion to the photoconductor is less likely to occur. Also, 70
By setting it to Am ² / kg or less, it is possible to suppress the mechanical force applied to the toner and prevent the toner from being crushed. Therefore, the saturation magnetization of the carrier is required to be in the range of ²⁰ to 70 Am ² / kg.

Second, the carrier is required to charge the toner quickly. That is, it is important to improve the mixing property with the toner, and for that purpose, it is required to have an appropriate specific gravity, particularly, a specific gravity of about 2.5 to 5.2. Although increasing the specific gravity of the carrier is advantageous for the mixing property with the toner itself, it is also required that the toner is not damaged, so that the so-called spent is prevented from occurring, and the developing machine is reduced in size and In order to reduce the weight, the specific gravity of the carrier is desirably small. Therefore, it is required that the specific gravity is appropriate, in particular, about 2.5 to 5.2.

[0011] The third point required for the carrier is a relatively high electric resistance value, especially 10 ¹¹ to 10 ¹⁵ Ω.
cm. That is,
When the volume resistivity is as low as 10 ⁶ Ωcm or less as in the case of an iron powder carrier, the charge is injected from the sleeve to cause the carrier to adhere to the image portion of the photoreceptor, or the latent image charge escapes through the carrier, and the latent image There are problems such as occurrence of disorder and loss of images.

In order to solve these problems, a binder type carrier in which the surface of the carrier particles is coated with a resin to increase the electric resistance of the carrier has been proposed (Japanese Patent Laid-Open No. 47-1395).
No. 4, JP-A-54-660).

However, since these resins are insulators, the electrical resistance of the carrier itself is likely to be higher than 10 ¹⁵ Ωcm, carrier charges are less likely to leak, and the charge amount of the toner is also increased. Although the obtained image is an image with a sharp edge, on the other hand, on a large-area image surface, there is a problem that the image density at the center becomes extremely low.

From these facts, a relatively high electric resistance value is required, and specifically, a specific volume resistance value of 10 ¹¹ to 10 is required.
^{About 15} Ωcm is required.

The resins used for the binder type carrier are roughly classified into thermoplastic resins such as vinyl, styrene and acrylic resins and thermosetting resins such as phenol resins, melamine resins and epoxy resins. Although a resin is known, it is generally considered that a thermoplastic resin which can be easily granulated is used, and a thermosetting resin has a practical problem because it is difficult to form a spheroid.

On the other hand, a thermosetting resin is more excellent in durability, impact resistance and heat resistance than a thermoplastic resin. Therefore, a binder type comprising inorganic particles and a thermosetting resin taking advantage of these advantages is used. A career is strongly demanded. Composite particles using a phenolic resin as a thermosetting resin and a ferromagnetic powder as inorganic particles are known (Japanese Unexamined Patent Publication No.
JP 220068, JP-A-4-100850)
However, there is no end to the demand for higher performance of the binder type carrier.

In general, phenolic resins as thermosetting resins are roughly classified into resole resins which react phenols and aldehydes in the presence of a basic catalyst, and novolak resins which react in the presence of an acidic catalyst. A resole resin is suitable for a spherical carrier in that it can be cured only by heating without using a curing agent because it contains many methylol groups in a molecule. However, on the other hand,
It also has the disadvantage that it is susceptible to temperature and humidity when mixed with toner due to the effects of residual groups.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide magnetic particle-dispersed composite particles which solve the above-mentioned problems and a method for producing the same.

An object of the present invention is to provide magnetic particle-dispersed composite particles capable of forming a high-quality toner image by preventing or suppressing the occurrence of fog without particle adhesion, and a method for producing the same.

An object of the present invention is to provide magnetic particle-dispersed composite particles capable of forming a high-definition color toner image with a high image density without being affected by temperature and humidity, and a method for producing the same.

An object of the present invention is to provide a magnetic particle-dispersed composite particle which is excellent in durability without image deterioration even when a large number of images are formed, and a method for producing the same.

[0022]

According to the present invention, there is provided a magnetic particle-dispersed composite particle containing at least a binder resin and magnetic particles, wherein the binder resin comprises phenols and aldehydes in the presence of at least an amine catalyst. The present invention relates to magnetic particle-dispersed composite particles, characterized in that they are made to react.

Further, the present invention provides a method for producing magnetic particle-dispersed composite particles containing at least a binder resin and magnetic particles, wherein the binder resin comprises phenols and aldehydes in the presence of at least an amine-based catalyst. The present invention relates to a method for producing magnetic particle-dispersed composite particles obtained by reacting.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted various studies and investigations to improve the above-mentioned conventional problems. As a result, phenols and aldehydes were used as binder resins in the presence of an amine-based catalyst, particularly with ammonia. The inventors have found that a reaction in the presence of a mixed catalyst of a tertiary amine is effective in improving various properties, and have completed the present invention.

That is, the resolving reaction mechanism is different between ammonia and tertiary amine. Ammonia enters the resin system to promote polymerization, and tertiary amine tends to promote the conversion of phenols to methylol. When only the polymerization is promoted, a large amount of unreacted phenol remains, and when only the methylolation is promoted, a low-molecular-weight methylolated product can be increased. Therefore,
By using ammonia and a tertiary amine in combination, it is possible to promote methylolation to reduce unreacted substances and promote polymerization to reduce low molecular weight substances.

As described above, when only the polymerization is promoted, a large amount of unreacted phenol remains, and when only the methylolation is promoted, many low-molecular-weight methylolated products can be produced.
First, unreacted phenol is reduced by using a tertiary amine as a catalyst, and then ammonia is added to cause a reaction, whereby the methylol phenols are reacted to polymerize. By doing so, low molecular weight substances in the entire system are reduced.

As described above, it is presumed that as a result of reducing the amount of low molecular substances in the entire system, the strength of the resin is improved and the resin is less affected by temperature and humidity.

In the present invention, in particular, phenols 1
Mixed catalyst of ammonia and tertiary amine 0.0
It is effective to carry out the reaction in the presence of 2 to 0.3 mol. If it is less than 0.02 times, the reaction between phenols and formaldehyde does not proceed sufficiently, and unreacted substances remain. On the other hand, if it exceeds 0.3 times, the reaction proceeds too much and the molecular weight becomes too high, so that it is difficult to control the spherical shape.

The tertiary amine used here is, for example, triethylamine, trimethylamine, tri-n-propylamine and benzyldimethylamine. The catalyst combination ratio is preferably in a molar ratio of ammonia: tertiary amine = 2: 8 to 8: 2. It is more effective to reduce the unreacted substances by further reacting phenols with tertiary amine as a catalyst and then adding ammonia to react.

JP-A-8-36276 also proposes a magnetic carrier using a phenolic resin as a binder resin, and describes ammonia water or an amine-based catalyst as a catalyst. However, the configuration of the present invention in which methylol is aggressively promoted and then polymerized is not suggested, and the effect is not always satisfactory.

Hereinafter, the configuration of the present invention will be described in detail.

First, the magnetic particle-dispersed composite particles (hereinafter referred to as magnetic carrier) according to the present invention have a 50% average particle diameter of 5 to 100 μm. Particles having an average particle diameter of less than 5 μm are liable to undergo secondary aggregation during carrier production, and particles having an average particle diameter of more than 100 μm make it impossible to obtain a clear image.
In particular, for high image quality and prevention of carrier adhesion, 1
0 to 60 μm, preferably 15 to 50 μm is good.

The magnetic carrier according to the present invention preferably contains ferromagnetic compound particles and non-magnetic inorganic compound particles, and the total amount of ferromagnetic compound particles and non-magnetic inorganic compound particles is from 60 to 60%.
It is 99% by mass, more preferably 80 to 99% by mass. If the amount is less than 60% by mass, an appropriate ratio of specific gravity cannot be obtained because the proportion of the resin increases, and if the amount exceeds 99% by mass, particles having sufficient strength cannot be obtained due to insufficient binder.

Further, the content of the non-magnetic inorganic compound particles is in the range of 5 to 70% by mass based on the total amount of the ferromagnetic compound particles and the non-magnetic inorganic compound particles. Preferably 10
It is in the range of ７０70% by mass. If less than 5% by mass,
A moderately high electric resistance cannot be obtained. In addition, 70% by mass
If it exceeds, it is not preferable because a sufficient magnetization value cannot be obtained.

The bulk density of the magnetic carrier of the present invention is 3.0.
g / cm ³ or less, more preferably 2.0 g / cm ³
cm ³ or less. If it exceeds 3.0 g / cm ³ , the share in the developer becomes large, and it becomes easy to cause spent by the toner or peeling of the coating layer. The measurement of the bulk density of the carrier is performed according to the method described in JIS K5101.

The shape of the magnetic carrier is appropriately selected so as to be convenient for a predetermined system. However, in the magnetic carrier used in the present invention, the shape factor SF-1 representing sphericity is 200 or less, more preferably 150 or less.
The following is preferred. The magnetic carrier is SF-1
Exceeds 200, the fluidity of the developer becomes inferior, the ability to impart frictional charge to the toner decreases, and the shape of the magnetic brush becomes uneven at the developing pole, making it difficult to obtain high-quality images. Become. The sphericity of the carrier was measured by randomly extracting 300 or more carriers using a field emission scanning electron microscope S-800 manufactured by Hitachi, Ltd., and using an image processing analyzer L manufactured by Nireco.
This is performed by obtaining SF-1 derived by the following equation using uzex3.

[0037]

(Equation 1) [Where MXLNG indicates the maximum diameter of the carrier, and ARE
A indicates the projected area of the carrier. ]

Here, SF-1 closer to 100 means closer to a sphere.

[0039] The ratio r _b / r _a between the average particle size r _b of the average particle diameter r _a nonmagnetic inorganic compound particles of the ferromagnetic compound particles in the magnetic carrier of the present invention, to be better than 1.0 preferable. More preferably, it is in the range of 1.2 to 5.0.
In the case of 1.0 or less, the difference in size between the ferromagnetic compound particles and the nonmagnetic inorganic compound particles disappears or the ferromagnetic compound particles become relatively larger, so that the ferromagnetic compound particles occupying the surface Will increase,
The electric resistance value of the carrier core material before the formation of the resin coating layer is reduced to less than 10 ¹⁰ Ωcm, and in order to obtain a relatively high electric resistance value, it is necessary to increase the thickness of the resin coating layer. Required. In addition, for uniform mixing, the ratio r _b / r _a is preferably 5.0 or less.

The magnetic carrier of the present invention has a saturation magnetization of 2
It is preferably 0-70 Am ² / kg, more preferably 20 Am ² / kg.
５０50 Am ² / kg. Saturation magnetization value is 70 Am ² / k
If the value exceeds g, the transportability due to the magnetic force of the carrier increases, and the mechanical force on the toner increases, which may cause the toner to be crushed. Further, the saturation magnetization value is 20 Am
If it is less than ² / kg, the carrier will be detached from the surface of the developing sleeve while the developer is being conveyed, and will adhere to the surface of the photoreceptor to cause a defect in the image.

The magnetic carrier according to the present invention has a specific gravity of 2.
It is preferably from 5 to 5.2. More preferably, 2.
5 to 4.5.

The magnetic carrier according to the present invention preferably has an electric resistance of 10 ¹¹ to 10 ¹⁵ Ωcm. 10 ¹¹
If it is less than Ωcm, the charge on the electrostatic latent image tends to flow through the carrier, and the image is likely to be disturbed or chipped. If it exceeds 10 ¹⁵ Ωcm, leakage of carrier charges hardly occurs, the charge amount of the toner increases, and problems such as extremely low image density at the center of the solid black portion occur.

Next, a method for producing the magnetic carrier according to the present invention as described above will be described.

The ferromagnetic compound particles used in the present invention include ferromagnetic iron oxide particles such as magnetite and maghemite, and metals other than iron (Mn, Ni, Zn, Mg, Cu, etc.).
Spinel ferrite particles containing one or more kinds of
Magnetoplumbite type ferrite particles such as barium ferrite, and fine particles of iron or iron alloy having an oxide film on the surface can be used. Preferred are ferromagnetic iron oxide particles such as magnetite or magnetic ferrite particles containing magnesium and iron. The particle size of the ferromagnetic compound particles,
The thickness is desirably 0.02 to 5 μm, and preferably 0.05 to 3 μm in consideration of the dispersion in an aqueous medium and the strength of the formed spherical composite particles. The shape may be any of a granular shape, a spherical shape, and a needle shape. Further, the ferromagnetic compound preferably has a saturation magnetization σ _s of 20 Am ² / kg or more, more preferably 30 Am ² / kg or more.

The nonmagnetic inorganic compound particles used in the present invention have an electric resistance of at least 10 ¹⁰ Ωcm, preferably 10 ¹⁰ Ωcm.
¹² Ωcm or more, for example, metal oxide fine particles such as titanium oxide, silica, alumina, zinc oxide, magnesium oxide, hematite, goethite and ilmenite, silicon carbide, aluminum nitride, boron nitride and the like can be used. . Those having little difference in specific gravity from ferromagnetic compound particles, hematite, zinc oxide, titanium oxide and the like are more preferable. The particle size of the non-magnetic inorganic compound particles is 0.0
It is preferably from 5 to 5 μm, and considering the dispersion in an aqueous medium and the strength of the formed composite particles, it is preferably 0.1 to 5 μm.
More preferably, it is 3 μm. The shape may be any of a granular shape, a spherical shape, and a needle shape. The nonmagnetic inorganic compound preferably has a saturation magnetization σ _s of 10 Am ² / kg or less, more preferably 5 Am ² / kg or less.

The ferromagnetic compound particles and nonmagnetic inorganic compound particles in the present invention can be used as they are without surface treatment, but may be subjected to lipophilic treatment in advance. When ferromagnetic compound particles and non-magnetic inorganic compound particles not subjected to lipophilic treatment are used, hydrophilic organic compounds such as carboxymethylcellulose and polyvinyl alcohol and fluorine compounds such as calcium fluoride are used as suspension stabilizers. By adding a compound or the like, spherical particles are easily generated.

The phenols used in the present invention include phenol itself, alkylphenols such as m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol, bisphenol A, and a part of benzene nucleus or alkyl group. Alternatively, compounds having a phenolic hydroxyl group, such as halogenated phenols, all of which are substituted with chlorine atoms or bromine atoms, may be mentioned, of which phenol is most preferred. When a substance other than phenols is used, particles may not be easily formed, or even if particles are formed, the particles may have an irregular shape.

Examples of the aldehyde used in the present invention include formaldehyde and furfural in either form of formalin or paraaldehyde, with formaldehyde being particularly preferred.

The molar ratio of the aldehyde to the phenol is preferably from 1 to 4, particularly preferably from 1.2 to 3. The molar ratio of aldehydes to phenols is 1
If the particle size is smaller, particles are difficult to be formed, and even if formed, the curing of the resin is difficult to progress, so that the strength of the formed particles tends to be weak. On the other hand, the molar ratio of aldehydes to phenols is 4 If it is larger than that, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

In the present invention, another resin can be used as a binder resin in accordance with the phenol resin to the extent that the effects of the present invention are not impaired.

In the present invention, the production of the magnetic carrier is carried out in an aqueous medium. In this case, the amount of water charged is determined by the total solid content which is the ratio of the total amount of the ferromagnetic compound particles and the non-magnetic inorganic compound particles to the entire raw material. 30-95% by mass
It is preferable that the content is particularly preferably 60 to 90% by mass.

In the reaction, first, phenols, aldehydes, water, ferromagnetic compound particles and non-magnetic inorganic compound particles are charged into a reaction vessel, and the mixture is sufficiently stirred. Then, the reaction temperature is adjusted to 70 to 90 ° C., and the phenol resin is cured. At this time, it is desirable to slowly raise the temperature in order to obtain a magnetic carrier core material having a high sphericity. The heating rate is preferably 0.5 to
It is 1.5 ° C / min, more preferably 0.8 to 1.2 ° C / min.

After the cured reaction product is cooled to 40 ° C. or lower, the resulting aqueous dispersion is separated into solid and liquid by a conventional method such as filtration and centrifugation, and then washed and dried to obtain a ferromagnetic compound. A magnetic carrier core material obtained by combining the particles and the non-magnetic inorganic compound particles with a phenol resin as a binder is obtained. The method of the present invention can be carried out by either a continuous method or a batch method, but is usually carried out by a batch method.

An example will be described more specifically.

After phenols, aldehydes, water and a magnetic carrier core material are charged into a reaction vessel and sufficiently stirred, triethylamine and ammonia are added, and the mixture is heated while stirring to adjust the reaction temperature to 70 to 90 ° C. And cure the phenolic resin. After the cured reaction product is cooled to 40 ° C. or lower, the obtained aqueous dispersion is separated into solid and liquid by a conventional method such as filtration and centrifugation, and then washed and dried to form a phenol resin layer. The formed magnetic carrier particles are obtained. At that time, in order to sufficiently cure the resin, for example, it is necessary to sufficiently cure the resin at a temperature of about 100 to 350 ° C. Further, under an inert atmosphere to prevent oxidation of the ferromagnetic compound particles, For example, it is desirable to perform the treatment while flowing an inert gas such as helium, argon, or nitrogen. As the heat treatment or the like, either a fixed type or a rotary type may be used, but a rotary type is preferable in order to prevent aggregation of particles.

In the magnetic carrier according to the present invention, the above magnetic carrier is used as a core material, and a coating layer made of one or more resins can be provided on the surface thereof. In the case of resin, the coating amount is 0.01 to 5 with respect to the carrier core material particles.
%, Preferably 0.05 to 3% by mass. If the amount of the resin to be coated is less than 0.01% by mass, the effect of sufficient coating cannot be obtained, and if it is more than 5% by mass, coalescence of particles or the like is likely to occur.

As the coating method, any of the conventionally known resin coating methods such as a method of dissolving or suspending a coating material such as a resin in a solvent, applying the coating material and attaching the coating material to a carrier, or a method of simply mixing with a powder. Can also be applied.

The amount of treatment (coating) of the coating material is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, based on the mass of the carrier after the treatment.

The 50% average particle size of these coated carriers is preferably 10 to 100 μm, more preferably 20 to 50 μm.
It may have a μm.

The coating resin may contain other resin particles or inorganic compound particles. Further, it is more preferable to modify the surface with another material such as a reactive coupling agent before coating the resin. By performing the surface modification, the adhesion between the resin layer and the carrier core material particles is improved, and more excellent durability can be obtained.

The reactive coupling agent for the magnetic carrier core material of the present invention includes the following coupling agents.

Examples of the silane coupling agent include those having a hydrophobic group, an amino group, and an epoxy group. Examples of the silane coupling agent having a hydrophobic group include vinyltrichlorosilane, vinyltriethoxysilane, and vinyl.
Tris (β-methoxy) silane and the like.

As silane coupling agents having an amino group, γ-aminopropyltriethoxysilane, N
-Β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like.

Examples of the silane coupling agent having an epoxy group include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane and the like. There is.

Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, and isopropyl tris (dioctyl pyrophosphate) titanate.

Among these, in order to further increase the affinity on the surface of the carrier core material and the negative chargeability when using a negative charge toner, the reactive coupling agent used is an aminosilane coupling agent. Those having a primary amino group are particularly preferred.

The above-mentioned magnetic coated carrier has a sharp particle size distribution, provides favorable triboelectric charging properties to the toner, and has the effect of improving electrophotographic properties.

When the magnetic carrier of the present invention is mixed with a toner to prepare a two-component developer, the mixing ratio is 2 to 15% by mass, preferably 4% by mass, as the toner concentration in the developer.
Good results are obtained when the content is set to １３13% by mass. When the toner density is less than 2% by mass, the image density becomes low,
If the content is more than 10% by mass, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

The toner used together with the magnetic carrier of the present invention has a weight average particle diameter of 1 to 10 μm, preferably 3 to 9 μm.
Preferably, it is in the range of μm.

The toner has a weight average particle diameter (D4) of 10 μm
Is exceeded, the toner particles for developing the electrostatic latent image become large, so that no matter how much the magnetic force of the magnetic carrier is lowered, development that is faithful to the latent image cannot be performed. Splattering becomes severe. In addition, the weight average particle size is 1
In the case of toner having a particle size of less than μm, there is a problem in handling properties as a powder.

The particle size of the toner is closely related to the particle size of the magnetic carrier. When the number average particle diameter of the magnetic carrier is 20 to 60 μm, the toner has a weight average diameter of 3
It is necessary that the thickness be 9 μm to improve the chargeability and further improve the image quality. On the other hand, when the number average particle diameter of the magnetic carrier is 5 to 35 μm, the toner has a weight average diameter of 1 to 6 μm in order to prevent deterioration of the developer and to improve the image quality at the initial stage and especially after the endurance. Is preferred.

Further, the toner preferably has a shape factor SF-1 of 100 to 150, more preferably 100 to 130.
Is that the filming resistance and the transferability in practical use /
Good for improving developability.

The toner having the above-mentioned shape factor is not only essential for faithfully reproducing finer latent image dots in order to improve the image quality, but also withstands a high mechanical stress in a developing device. Deterioration can be reduced. Further, transferability / developability during high-speed copying can be sufficiently ensured. When the shape factor SF-1 of the toner is larger than 150, the toner becomes more irregular than a spherical shape, so that it becomes difficult to obtain uniform charging characteristics, and in addition to adverse effects such as impairing fluidity, Since the friction between the toners or between the toner and the charge applying member such as the carrier is increased, the toner is damaged and finely divided, and the formed image is easily fogged, and the definition is reduced.

As the binder resin used for the toner, the following binder resins can be used.

For example, homopolymers of styrene and its substituted substances such as polystyrene, poly-p-chlorostyrene and polyvinyl toluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride; phenolic resin; natural modified phenolic resin; natural resin modified maleic acid resin; acrylic resin; methacrylic resin; polyvinyl acetate; silicone resin; polyester resin; A xylene resin; a polyvinyl butyral; a terpene resin; a cumarone indene resin; Preferred binders include styrene copolymers and polyester resins.

The number-average molecular weight of the THF-soluble component of the binder resin of the toner is from 3,000 to 1,000,000, preferably from 5,000 to 200,000.

The styrene-based polymer or styrene-based copolymer may be cross-linked, or may be a mixed resin of a cross-linked resin and a non-cross-linked resin.

As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; ,
Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups are used alone or as a mixture.

The amount of the cross-linking agent to be added is as follows.
0.001 to 10 parts by mass relative to 00 parts by mass is preferred.

The toner may contain a charge controlling agent or a release agent such as wax.

Additives for imparting various toner properties should have a particle size of 1/5 or less of the volume average particle size of the toner particles from the viewpoint of durability when added to the toner or externally added to the toner. Is preferred. The particle size of the additive means an average particle size obtained by observing the surface of the toner particles with an electron microscope. The toner preferably has an externally added additive, and the additive has a shape factor SF-1 on the toner of 150 or more, preferably larger than 180, and more preferably larger than 200. This is good for suppressing burial on the surface. As additives for imparting these properties, for example, the following are used.

Examples of the fluidity-imparting agent include metal oxides such as silicon oxide, aluminum oxide and titanium oxide;
Carbon black; and carbon fluoride.
Each of these is preferably subjected to a hydrophobic treatment.

Examples of the abrasive include metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; and calcium sulfate and sulfuric acid. Metal salts such as barium and calcium carbonate are mentioned.

Examples of the lubricant include fluorine resin powders such as vinylidene fluoride and polytetrafluoroethylene; and fatty acid metal salts such as zinc stearate and calcium stearate.

The charge control particles include, for example, tin oxide,
Metal oxides such as titanium oxide, zinc oxide, silicon oxide and aluminum oxide; and carbon black.

These additives are preferably used in an amount of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the toner particles. These additives may be used alone or in combination of two or more.

The toner can be manufactured using a pulverized toner manufacturing method and a polymerized toner manufacturing method.

As a developing method using the toner and the magnetic carrier of the present invention, for example, development can be performed using a developing means as shown in FIG. Specifically, it is preferable to perform development in a state where the magnetic brush is in contact with the latent image carrier, for example, the photosensitive drum 1 while applying an alternating electric field.
The distance (SD distance) B between the developer carrier (developing sleeve) 11 and the photosensitive drum 1 is preferably 100 to 1000 μm in terms of preventing carrier adhesion and improving dot reproducibility. If the width is less than 100 μm, the supply of the developer tends to be insufficient, and the image density becomes low.
If it exceeds, the lines of magnetic force from the magnet S1 are widened and the density of the magnetic brush is lowered, and the dot reproducibility is deteriorated, the force for restraining the magnetic carrier is weakened, and carrier adhesion is likely to occur.

The voltage between the peaks of the alternating electric field is 300 to 30.
00V is preferable, the frequency is 500 to 10000 Hz,
Preferably, it is 1000-7000 Hz, and each can be appropriately selected and used depending on the process. In this case, the waveform may be triangular, rectangular, sine, or D
Various selections such as a waveform with a changed duty ratio and an intermittent alternating electric field superposition can be used. 300V applied voltage
If it is lower, sufficient image density is difficult to obtain, and fog toner in the non-image area may not be collected well. If the voltage exceeds 3000 V, the latent image may be disturbed via the magnetic brush, and the image quality may be degraded.

By using a two-component developer having a well-charged toner, the fog removal voltage (Vback)
And the primary charge of the photoconductor can be reduced, so that the life of the photoconductor can be extended. Vbac
k is preferably 200 V or less, more preferably 150 V or less, depending on the developing system.

The contrast potential is preferably from 100 to 400 V so that a sufficient image density can be obtained.

When the frequency is lower than 500 Hz, although it is related to the process speed, a sufficient oscillating electric field is not given to the toner in contact with the photosensitive member to return to the developing sleeve.
Fog tends to occur. If the frequency exceeds 10,000 Hz, the toner cannot follow the electric field, and the image quality is likely to deteriorate.

Further, in the output of a full-color image in which halftone is particularly important, three or more developing devices for magenta, cyan, and yellow are used, and the developer and the developing method according to the present invention are used. In particular, in combination with a developing system that forms a digital latent image, it is possible to develop the dot latent image faithfully without being affected by the magnetic brush and disturbing the latent image. Also in the transfer step, a high transfer rate can be achieved by using a fine-particle-cut toner having a sharp particle size distribution, so that high image quality can be achieved in both the halftone portion and the solid portion.

Furthermore, by using the two-component developer according to the present invention together with the initial improvement in image quality, the share of the developer in the developing device is small, and the image quality does not deteriorate even when copying a large number of sheets. The effects of the invention can be fully exhibited.

In order to obtain a tighter image, it is preferable that developing devices for magenta, cyan, yellow, and black are provided, and a tighter image is exhibited by the final development of black. it can.

On the other hand, it is also possible to transfer the electrostatic latent toner image formed on the latent image holding member to a recording material via an intermediate transfer member.

That is, in this image forming method, the toner image formed by developing the electrostatic latent image formed on the latent image holding member is transferred to an intermediate transfer member, and the toner image transferred to the intermediate transfer member is Is transferred to a recording material.

With reference to FIG. 3, an example of an image forming method using an intermediate transfer member will be specifically described.

In the apparatus system shown in FIG. 3, the cyan developing device 254-1, the magenta developing device 254-2, the yellow developing device 254-3, and the black developing device 254-4 have a cyan developer and a magenta A magenta developer having a toner, a yellow developer having a yellow toner, and a black developer having a black toner have been introduced. An electrostatic latent image is formed on a photosensitive member 251 as a latent image holding member by a latent image forming means 253 such as a laser beam. An electrostatic charge image formed on the photoconductor 251 is developed by using a developer such as a magnetic brush development system, a non-magnetic one-component development system, or a magnetic jumping development system.
1 is formed. The photosensitive member 251 is a photosensitive drum or a photosensitive belt having a conductive substrate 251b and a photoconductive insulating material layer 251a such as amorphous selenium, magnetized cadmium, zinc oxide, organic photoconductor, and amorphous silicon formed on the conductive substrate 251b. is there. The photoconductor 251 is rotated in a direction indicated by an arrow by a driving device (not shown). As the photoconductor 251, a photoconductor having an amorphous silicon photosensitive layer or an organic photosensitive layer is preferably used.

The organic photosensitive layer may be a single layer type in which the photosensitive layer contains a charge generating substance and a substance having a charge transporting property in the same layer, or a functionally separated type photosensitive layer comprising the charge transporting layer and the charge generating layer as components. Any of them may be used. A laminated photosensitive layer having a structure in which a charge generation layer and then a charge transport layer are laminated on a conductive substrate in this order is one of preferred examples.

As the binder resin for the organic photosensitive layer, a polycarbonate resin, a polyester resin, or an acrylic resin has good cleaning properties, and poor cleaning, toner fusion to the photoreceptor, and filming hardly occur.

In the charging step, there are a non-contact type using a corona charger and a contact type using a contact charging member such as a roller, and both types are used. For efficient uniform charging, simplification, and low ozone generation, a contact-type system as shown in FIG. 3 is preferably used.

A charging roller 252 as a primary charging member
Is basically composed of a central metal core 252b and a conductive elastic layer 252a forming an outer periphery. The charging roller 252 is pressed against the surface of the photoconductor 251 with a pressing force, and rotates following the rotation of the photoconductor 251.

As a preferable process condition when the charging roller is used, the contact pressure of the roller is 4.9 to 490.
N / m (5 to 500 g / cm), when an AC voltage superimposed on a DC voltage is used, the AC voltage = 0.5 to
5 kVpp, AC frequency = 50 Hz to 5 kHz, DC voltage = ± 0.2 to ± 0.5 kV.

Other contact charging members include a method using a charging blade and a method using a conductive brush. These contact charging members have the effect of eliminating the need for high voltage and reducing the generation of ozone.

The material of the charging roller and the charging blade as the contact charging member is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the release coating, a nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride), or a fluorine acrylic resin can be used.

The voltage of the toner image on the photosensitive member (for example, ± 0.
(± 1 kV) is applied to the intermediate transfer member 255 to which the voltage is applied. The intermediate transfer member 255 is a pipe-shaped conductive core 2
55b and a medium-resistance elastic layer 255a forming the outer peripheral surface thereof
Consists of The core metal 255b may be one in which a conductive layer (for example, conductive plating) is provided on the surface of plastic.

The medium resistance elastic layer 255a is made of silicone rubber, Teflon rubber, chloroprene rubber, urethane rubber,
Elastic materials such as EPDM (ethylene-propylene-diene terpolymer) include carbon black, zinc oxide,
This is a solid or foamed layer in which a conductivity imparting agent such as tin oxide or silicon carbide is mixed and dispersed to adjust the electric resistance (volume resistivity) to a medium resistance of 10 ⁵ to 10 ¹¹ Ωcm.

The intermediate transfer member 255 is provided in parallel with the photosensitive member 251 and is disposed in contact with the lower surface of the photosensitive member 251. The intermediate transfer member 255 is counterclockwise indicated by an arrow at the same peripheral speed as the photosensitive member 251. Rotate.

The first color toner image formed and carried on the surface of the photosensitive member 251 is transferred by the transfer bias applied to the intermediate transfer member 255 while passing through the transfer nip where the photosensitive member 251 contacts the intermediate transfer member 255. The intermediate transfer is sequentially performed on the outer surface of the intermediate transfer body 255 by the electric field formed in the nip portion.

The untransferred toner on the photosensitive member 251 that has not been transferred to the intermediate transfer member 255 is cleaned by the photosensitive member cleaning member 258 and collected in the photosensitive member cleaning container 259.

A transfer means is provided in parallel with the intermediate transfer body 255 and is brought into contact with the lower surface of the intermediate transfer body 255. The transfer means is, for example, a transfer roller 257 and has the same circumference as the intermediate transfer body 255. Rotate in the clockwise direction of the arrow at speed. The transfer roller 257 is a direct intermediate transfer member 255
, Or a belt or the like may be arranged to contact between the intermediate transfer member 255 and the transfer roller 257.

[0113] The transfer roller 257 is
b and a conductive elastic layer 257a forming the outer periphery thereof.

For the intermediate transfer member and the transfer member, general materials can be used. By setting the volume resistivity of the transfer member smaller than the volume resistivity of the intermediate transfer member, the voltage applied to the transfer member can be reduced, and a good toner image can be formed on the transfer material, and Winding around the intermediate transfer member can be prevented. In particular, it is preferable that the volume resistivity of the elastic layer of the intermediate transfer member is at least 10 times higher than the volume resistivity of the elastic layer of the transfer member.

The hardness of the intermediate transfer member and the transfer member is determined according to JIS.
It is measured according to K-6301. The intermediate transfer member is 10
It is preferable that the elastic layer is formed of an elastic layer belonging to the range of 40 to 40 degrees. The hardness of the elastic layer of the transfer member is preferably higher than the hardness of the elastic layer of the intermediate transfer member and has a value of 41 to 80 degrees in order to prevent the recording material from winding around the intermediate transfer member. When the hardness of the elastic layer of the transfer member is lower than the hardness of the elastic layer of the intermediate transfer member, a concave portion is formed on the transfer member side, and the recording material is likely to be wound around the intermediate transfer member.

As the transfer member, for example, a transfer roller is used, and the transfer roller 257 is rotated at a constant speed or a peripheral speed different from that of the intermediate transfer member 255. Recording material 2
56 is conveyed between the intermediate transfer member 255 and the transfer roller 257, and at the same time, a bias having a polarity opposite to that of the triboelectric charge of the toner is applied to the transfer roller 257 from the transfer bias unit, so that The toner image is transferred to the surface side of the recording material 256.

The transfer residual toner on the intermediate transfer member that has not been transferred to the recording material 256 is cleaned by the intermediate transfer member cleaning member 260 and collected in the intermediate transfer member cleaning container 262. The toner image transferred to the recording material 256 is heated and fixed by the heat fixing device 261.
Is established.

As the material of the transfer roller, the same material as that of the charging roller can be used. The preferable transfer process condition is that the contact pressure of the roller is 2.94 to 49.
0 N / m (3-500 g / cm), more preferably 1
DC voltage = ± 0.2 to ± 10 at 9.6 to 294 N / m
kV.

If the linear pressure as the contact pressure is less than 2.94 N / m, it is not preferable because the conveyance of the recording material and the occurrence of transfer failure tend to occur.

The conductive elastic layer 257 of the transfer roller 257
b is an elastic material such as polyurethane rubber or EPDM (ethylene-propylene-diene terpolymer) mixed with a conductivity-imparting agent such as carbon black, zinc oxide, tin oxide, and silicon carbide, and dispersed and dispersed therein to obtain an electric resistance value (volume). 10)
^{6-10 10} to adjust the resistance in the [Omega] cm, a layer of a solid or foamed meat.

The methods for measuring the properties are described below.

The 50% average particle size of the magnetic carrier of the present invention was measured by a laser diffraction type particle size distribution meter (manufactured by Horiba, Ltd.).

The magnetic characteristics of the magnetic carrier were measured using an oscillating magnetic field type magnetic characteristics automatic recording apparatus BHV-3 manufactured by Riken Denshi Co., Ltd.
Measure using 0. Magnetic characteristic values of the magnetic carrier powder,
An external magnetic field of _79.6 kA / m (1000 Oe) is created, and the magnetization intensity (σ _79.6 ) at that time is determined. The magnetic carrier is prepared in a state of being packed sufficiently in a cylindrical plastic container having a volume of about 0.07 cm ³ so as to be sufficiently dense. In this state, the magnetization moment is measured, the actual volume when the sample is put in is measured, and the magnetization intensity per unit volume is obtained.

The electric resistance of the magnetic carrier or the carrier core is measured by using a measuring device shown in FIG. In cell E,
The magnetic carrier or core is filled, the electrodes 31 and 32 are arranged so as to be in contact with the filled magnetic carrier or core 37, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain an electric resistance value. Ask. In the above measurement method, the magnetic carrier or the core is a powder, so that a change occurs in the filling rate, and accordingly, the electric resistance value may change. The measurement conditions of the electric resistance value are as follows:
Contact area S between filled magnetic carrier or core and electrode
= Approximately 2.3 cm ² , thickness d = approximately 2 mm, load of upper electrode 32 = 180 g, and applied voltage = 100 V.

The number average particle diameter of the ferromagnetic compound and the non-magnetic inorganic compound is determined by using a transmission electron microscope H-manufactured by Hitachi, Ltd.
Using a photographic image magnified 5000 to 20000 times by 800, 3 particles having a particle size of 0.01 μm or more
More than 00 pieces were extracted, and the ferrite compound and the non-magnetic inorganic compound were measured with the Feret diameter in the horizontal direction as the particle diameter of the ferrite compound and the nonmagnetic inorganic compound using an image processing analyzer Luzex3 manufactured by Nireco Co., Ltd., and averaged to calculate the number average particle diameter. I do.

The electric resistance of the ferromagnetic compound and the nonmagnetic inorganic compound is measured according to the method of the electric resistance of the carrier. The cell E of FIG. 2 is filled with a ferromagnetic compound and a nonmagnetic inorganic compound, electrodes 31 and 32 are arranged so as to be in contact with the filled ferromagnetic compound and the nonmagnetic inorganic compound, and a voltage is applied between the electrodes. The electrical resistance is determined by measuring the current flowing at that time. When filling the ferromagnetic compound and the non-magnetic inorganic compound, the filling is performed while rotating the upper electrode 31 left and right so that the electrode uniformly contacts the sample. In the above measuring method, the measuring conditions of the electric resistance are as follows: the contact area S between the filled ferromagnetic compound and the nonmagnetic inorganic compound and the electrode is about 2.
3 cm ² , thickness d = about 2 mm, load 18 on the upper electrode 32
0 g and an applied voltage of 100 V.

A specific example of the measurement of the toner particle size will be described below.

0.1 to 5 ml of a surfactant (alkylbenzenesulfonate) is added to 100 to 150 ml of the electrolyte solution, and 2 to 20 mg of a measurement sample is added thereto. The electrolysis solution in which the sample was suspended was subjected to dispersion treatment for 1 to 3 minutes using an ultrasonic disperser, and the above-mentioned Coulter counter multisizer was used to adjust the volume to 0.1 μm based on the volume using an aperture appropriately adjusted to a toner size of 17 μm or 100 μm. 3 ~
A particle size distribution of 40 μm is to be measured. The number average particle diameter and the weight average particle diameter measured under these conditions are obtained by computer processing, and the cumulative ratio of the number average particle diameter smaller than 1/2 times the diameter cumulative distribution is calculated from the number-based particle diameter distribution,
A cumulative value equal to or smaller than the 1/2 diameter cumulative distribution is obtained. Similarly, a cumulative ratio equal to or larger than the double diameter cumulative distribution of the weight average particle diameter is calculated from the volume-based particle size distribution, and a cumulative value equal to or larger than the double diameter cumulative distribution is obtained.

A method for measuring the triboelectric charge amount will be described.

The toner and the magnetic carrier are mixed so that the mass of the toner becomes 5% by mass, and mixed with a Turbula mixer for 60 seconds. Put this mixed powder (developer) in a metal container equipped with a 500-mesh conductive screen at the bottom,
Suction is performed with a suction device, and the amount of triboelectric charging is determined from the difference in mass before and after suction and the potential accumulated in a condenser connected to the container. At this time, the suction pressure is set to 250 mmHg. With this method, the triboelectric charge amount is calculated using the following equation.

Q (μC / g) = (C × V) × (W ₁ −W ₂ ) ⁻¹ (where W ₁ is the mass before suction, W ₂ is the mass after suction, and C is The capacity of the capacitor, V, is the potential stored in the capacitor.)

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the examples.

[0133]

[Examples] (Manufacturing Example 1) 50 parts by mass of phenol 75 parts by mass of formalin 37% by mass 50 parts by mass of water 50% by mass of silane coupling agent-treated magnetite (particle diameter 0.24 μm, electric resistance value 5 × 10) ^{5 Ωcm, σs70Am 2 / kg)} 350 weight parts silane coupling agent α-Fe ₂ O ₃ (particle size 0.6 .mu.m, the electric resistance value 8 × 10 ¹² Ωcm, the σs0Am ² / kg) 150 weight parts, 1 The mixture was placed in a 4-liter four-necked flask, and the temperature was maintained at 70 ° C. for 40 minutes while stirring and mixing.
The reaction was performed at 0 ° C. for 2 hours. Thereafter, the temperature was raised to 85 ° C., ammonia water was added in a molar ratio of 0.07 times with respect to phenol, and the mixture was reacted and cured for 60 minutes. After cooling to 30 ° C. and addition of 0.5 liter of water, the supernatant was removed, the precipitate was washed with water and air-dried. Next, this was dried at 60 ° C. for 24 hours under reduced pressure (5 mmHg) to obtain a magnetic carrier core material A.

A coating layer was provided on the surface of the obtained core material by the following method.

Using toluene as a solvent, a solution of 5% by weight of aminopropyltrimethoxysilane was prepared. While continuously applying a shear stress to the solution, the toluene is volatilized to coat the carrier core material so that the treatment amount becomes 0.1% by mass, and the carrier core material has a wettability to the silicone resin. Modification was performed.

Next, a carrier coat solution of 10% by mass of silicone resin was prepared using toluene as a solvent. While continuously applying shear stress to the coating solution, the solvent was volatilized to coat the carrier core material with a treatment amount of 0.7% by mass. Thereafter, the mixture was cured at 140 ° C. for 2 hours, and after loosening the coagulation, the particles were classified with a sieve having openings of 77 μm (200 mesh) to obtain a magnetic carrier I. The magnetic carrier I obtained had an SF-1 of 109 and a 50% average particle diameter of 35 μm.
m, electric resistance value is 6.8 × 10 ¹³ Ωcm, 79.6 kA
/ Strength sigma _79.6 of magnetization in m was 41Am ² / kg.

(Carrier Production Example 2) In the same manner as in Production Example 1, except that the amount of triethylamine used was 0.12 times and no ammonia was used, SF-1 was reduced to 11%.
3. 50% average particle size is 37 μm, electric resistance value is 1.6 ×
A magnetic carrier II having 10 ¹³ Ωcm and σ _79.6 of 42 Am ² / kg was obtained.

(Production Example 3 of Carrier) In Production Example 2, except that the used amount of triethylamine was increased by 0.018 times, SF-1 was 107, the 50% average particle diameter was 33 μm, and the electric resistance value was 8.2 × 10 ¹² Ωcm, σ _79.6
Was 42 Am ² / kg.

(Production Example 4 of Carrier) The same operation as in Production Example 1 was carried out except that 0.12 times of triethylamine and 0.21 times of aqueous ammonia were used.
15, 50% average particle size is 38 μm, electric resistance value is 3.1
A magnetic carrier IV having × 10 ¹³ Ωcm and σ _79.6 of 41 Am ² / kg was obtained.

(Preparation Example 5 of Carrier) The same procedure as in Preparation Example 3 was carried out except that 0.018-fold aqueous ammonia was used. As a result, the curing reaction was insufficient and the magnetic particles could not be bound well. No carrier particles were formed. This is presumed to be due to a large amount of unreacted monomer remaining because only the ammonia was used as the catalyst and no tertiary amine was used.

(Carrier Production Example 6) The same procedure as in Production Example 4 was carried out except that 0.33 times of aqueous ammonia was used. As a result, the particles coalesced and uniform carrier particles could not be obtained. Was. This is presumed to be because the curing reaction could not be controlled because only a large amount of aqueous ammonia was used as the catalyst, and the curing at the particle interfaces was promoted.

(Production Example 7 of Carrier) In the same manner as in Production Example 1, except that a tertiary amine as a catalyst and aqueous ammonia were added at the same time, SF-1 was 109, the 50% average particle diameter was 35 μm, and the electric resistance was 50%. Value is 5.1 × 10 ¹³ Ωc
A magnetic carrier V having m and σ _79.6 of 41 Am ² / kg was obtained.

(Production Example 1 of Toner) Ion-exchanged water 710
The parts by weight was charged with 0.1M-Na ₃ PO ₄ aqueous solution 450 parts by mass, followed by heating to 60 ° C., using a TK-type homomixer (Tokushu Kika Kogyo), and stirred at 1300 rpm.
To this, 68 parts by mass of a 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ . 160 parts by mass of styrene 34 parts by mass of n-butyl acrylate 12 parts by mass of copper phthalocyanine pigment 2 parts by mass of metal compound ditertiary butylsalicylate 10 parts by mass of saturated polyester (acid value 11 mgKOH / g, peak molecular weight 8500) Monoester 20 parts by mass of wax (Mw: 500, Mn: 400, Mw / Mn: 1.25, melting point: 69 ° C, viscosity: 6.5 mPa · s, Vickers hardness: 1.1, SP value: 8.6)

The above formulation was heated to 60 ° C.
12,000 rpm using Kisa (Special Kika Kogyo)
And homogeneously dissolved and dispersed. The polymerization initiator 2, 2 '
-Azobis (2,4-dimethylvaleronitrile) 10 g
Was dissolved to prepare a polymerizable monomer composition. The aqueous medium
The above-mentioned polymerizable monomer composition is charged into the body, _Two
In an atmosphere, Clare Mixer (M Technique Co., Ltd.)
) At 10,000 rpm for 10 minutes.
The monomer composition was granulated. After that, the aqueous medium is paddle-stirred
While stirring with the wings, raise the temperature at 80 ° C and keep the pH at 6.
The polymerization reaction was performed for 10 hours.

After the completion of the polymerization reaction, the mixture was cooled, hydrochloric acid was added to dissolve calcium phosphate, and then filtered, washed with water and dried to obtain polymer particles (toner particles).

The obtained polymer particles were analyzed by a transmission electron microscope (T
The core / shell structure in which the wax was encapsulated in the outer shell resin layer was confirmed by the tomographic plane measurement method of the polymer particles using EM).

The binder resin of the polymer particles obtained was S
The P value was 19 and the Tg was 60 ° C.

With respect to 100 parts by mass of the obtained polymer particles (toner particles), 0.7 parts by mass of hydrophobic titanium oxide having a primary particle size of 30 nm and SF having a primary particle size of 30 nm were used.
0.7 parts by mass of hydrophobic silica having a -1 of 205 was externally added by a Henschel mixer and passed through a # 330 mesh sieve. Then, the weight average particle size was 7.2 μm, and SF-1 was 108.
Was obtained.

(Production Example 2 of Toner) 100 parts by mass of polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 4 parts by mass of phthalocyanine pigment 4 parts by mass of aluminum complex of di-tert-butylsalicylic acid 4 parts by mass of Henschel The mixture was sufficiently preliminarily mixed by a mixer, melt-kneaded by a twin-screw extruder, cooled, coarsely ground to about 1 to 2 mm using a hammer mill, and then finely ground by an air jet type fine mill. Further, the obtained finely pulverized material was classified to have a weight average particle size of 5.8 μm and SF
A negatively triboelectric cyan powder having -1 = 142 was obtained.

Using the above powder, a cyan toner 2 was obtained in the same manner as in Production Example 1.

(Toner Production Examples 3 to 5) In the same manner as in Production Example 1, except that quinacridone, Pigment Yellow 93, and carbon black were used instead of the copper phthalocyanine pigment, magenta toner 3, yellow toner 4, and black toner 5 I got

<Example 1> A two-component developer 1 was prepared by mixing 92 parts by mass of the magnetic carrier I with 8 parts by mass of the cyan toner 1.

Using this two-component developer 1, a commercially available digital copying machine GP55 (manufactured by Canon Inc.) was modified as an image forming apparatus so that the developing device and charging device shown in FIG. 1 could be inserted, and the developing bias shown in FIG. Using the used one, the fixing device was changed to a roller whose surface layer was covered with PFA by 1.2 μm for both the heating roller and the pressure roller, and the structure was modified to remove the oil application mechanism. , 23 ° C./60% (N / N) environment, a paper passing test of 10,000 sheets was performed, and the evaluation was made based on the following evaluation method.
The results are shown in Table 1. As can be seen from Table 1, good results were obtained.

(1) Image density: Macbeth Densitometer RD918 type (Macbeth Densitometer R) equipped with an SPI filter
D918 manufactured by Macb
eth Co. ) Was measured as the relative density of the image formed on plain paper.

(2) Carrier adhesion: A solid white image was formed, and a portion of the photosensitive drum between the developing section and the cleaner section was sampled by closely attaching a transparent adhesive tape to the sample, and sampled at 5 cm.
The number of magnetic carrier particles adhering on the photosensitive drum in a size of 5 cm is counted, and the number of adhering carrier particles per 1 cm ² is calculated. A: Less than 5 B: 5 to less than 10 C: 10 to less than 20 D: 20 or more

3) Fog: The average reflectance Dr (%) of plain paper before image output was measured using a reflectometer ("REFLECOMETER ODEL TC-6" manufactured by Tokyo Denshoku Co., Ltd.).
DS "). On the other hand, a solid white image was formed on plain paper, and the reflectance Ds (%) of the solid white image was measured. Fog (%) is calculated from the following equation: Fog (%) = Dr (%)-Ds (%). A: less than 0.4% B: 0.4 to less than 0.8% C: 0.8 to less than 1.2% D: 1.2% or more

<Example 2> When the same procedure as in Example 1 was carried out except that the magnetic carrier II was used, good results were obtained although fog suppression after 10,000 sheets was slightly deteriorated. This is presumed to be due to the fact that the use of ammonia was not used as a catalyst, so that the polymerization became slightly insufficient, and the toner spent resistance was slightly reduced.

Example 3 The same procedure as in Example 1 was carried out except that the magnetic carrier III was used. Although all of the results were inferior in image density, carrier adhesion suppression and fog suppression, there was no practical problem. Was obtained. This is presumed to be because sufficient polymerization was not achieved due to a small amount of the catalyst.

<Example 4> The same procedure as in Example 1 was carried out except that the magnetic carrier IV was used, but good results were obtained although fog suppression after 10,000 sheets was slightly deteriorated. This is presumably because the amount of the catalyst was large and the binding strength was slightly reduced due to the influence of the low molecular weight methylolated product.

Example 5 The same operation as in Example 1 was carried out except that the magnetic carrier V was used, but good results were obtained although the carrier adhesion after 10,000 sheets was slightly deteriorated. This is presumably because the composition of the binder resin became slightly nonuniform because the flow of polymerization was not thoroughly performed after the formation of methylol due to the simultaneous addition of the two catalysts.

<Example 6> The procedure of Example 1 was repeated, except that the magnetic carrier core material A was used.
Although the fog suppression was slightly deteriorated, a result having no practical problem was obtained. This is presumably because the core was not coated with the core material, so that the ability to impart charge to the toner became slightly non-uniform.

[0162]

[Table 1]

<Example 7> The same operation as in Example 1 was carried out except that the cyan toner 2 was used. As a result, although the fog suppression was deteriorated, the level was practically acceptable. This is presumed to be due to non-uniform charging due to the irregular shape of the toner.

<Eighth Embodiment> A two-component developer with a magnetic carrier I was prepared in the same manner as in the first embodiment using toners 3, 4, 1, and 5, and a full-color image forming apparatus having the structure shown in FIG. , Without using a cleaning unit, yellow,
When 10,000 images were printed in the order of magenta, cyan, and black, good results were obtained with little image density deterioration and no fog even in full-color image formation.

Example 9 The same procedure as in Example 8 was carried out except that the full-color image forming apparatus shown in FIG. 3 was used, and good results were obtained.

[0166]

According to the present invention, a low molecular weight component in a binder resin of a magnetic carrier can be reduced, and a high-definition color image with high image density can be obtained over a long period of time by using a two-component developer. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic view of a developing device suitable for the present invention.

FIG. 2 is a schematic diagram of an apparatus used for measuring an electric resistance value.

FIG. 3 is a schematic view of another image forming apparatus suitable for the present invention.

FIG. 4 is a diagram showing still another example of an image forming apparatus suitable for the present invention.

FIG. 5 is a diagram showing an alternating electric field used in the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Latent image carrier (photosensitive drum) 11 Developing sleeve (developer carrier) 12 Magnet roller 18 Supply toner 19 Developer 19a Toner 19b Carrier 21 Transport sleeve 22 Magnetic particles 31 Lower electrode 32 Upper electrode 33 Insulator 34 Ammeter Reference Signs List 35 constant voltage device 36 power supply 37 carrier 38 guide ring d sample thickness E low resistance measurement cell 60a transfer bias applying means 61a photoconductor drum 62a primary charger 63a developing device 64a transfer blade 65a toner hopper 66a replenishing roller 67a exposure device 68 transfer material Carrier 69 Separation charger 70 Fixing unit 71 Fixing roller 72 Pressure roller 73 Wep 75, 76 Heating unit 78 Temperature detection unit 79 Transfer belt cleaning device 80 Driving roller 81 Belt driven roller 82 Bell Discharger 83 registration rollers 84 feed roller Pa, Pb, Pc, Pd developing unit

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazumi Yoshizaki 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H005 BA03 BA06 CA15 CA26 CA28 CB03

Claims (20)

[Claims] 1. A magnetic particle-dispersed composite particle containing at least a binder resin and magnetic particles, wherein the binder resin is obtained by reacting a phenol and an aldehyde in the presence of at least an amine catalyst. A magnetic particle-dispersed composite particle characterized by the following. 2. The magnetic particle-dispersed composite particles according to claim 1, wherein the catalyst is a tertiary amine-containing compound. 3. The catalyst according to claim 1, wherein the catalyst is a combination of ammonia and a tertiary amine-containing compound.
2. The magnetic particle-dispersed composite particles according to 1.). 4. The mixed catalyst of ammonia and a tertiary amine-containing compound is used in an amount of from 0.02 to 1 mol of phenols.
4. The magnetic particle-dispersed composite particles according to claim 3, wherein the amount is 0.3 mol. 5. The magnetic particle-dispersed composite particles according to claim 1, wherein the composite particles contain non-magnetic particles in addition to the magnetic particles. 6. The composite particle according to claim 1, wherein the composite particle contains magnetic particles or magnetic particles and non-magnetic particles in an amount of 60 to 99% by mass based on the composite particles. Magnetic particle-dispersed composite particles. 7. The magnetic particle-dispersed composite particle according to claim 1, wherein the composite particle is further coated with an organic compound. 8. The magnetic particle-dispersed composite particles according to claim 7, wherein the organic compound contains at least a reactive coupling agent. 9. The composite particles having a 50% average particle size of 5-1.
The magnetic particle-dispersed composite particle according to any one of claims 1 to 8, wherein the particle diameter is 00 µm. 10. The method according to claim 1, wherein the binder resin is obtained by reacting a phenol and an aldehyde with a tertiary amine as a catalyst and further adding an ammonia catalyst. The magnetic particle-dispersed composite particles according to any one of the above. 11. A method for producing magnetic particle-dispersed composite particles containing at least a binder resin and magnetic particles, wherein the binder resin is obtained by reacting a phenol and an aldehyde in the presence of at least an amine-based catalyst. A method for producing magnetic particle-dispersed composite particles, comprising: 12. The method for producing magnetic particle-dispersed composite particles according to claim 11, wherein the catalyst is a tertiary amine-containing compound. 13. The method according to claim 11, wherein the catalyst is a combination of ammonia and a tertiary amine-containing compound. 14. The mixed catalyst of the ammonia and the tertiary amine-containing compound is used in an amount of 0.02 to 1 mol of phenol
The method for producing magnetic particle-dispersed composite particles according to claim 13, wherein the amount is from 0.3 to 0.3 mol. 15. The method according to claim 11, wherein the composite particles contain non-magnetic particles in addition to the magnetic particles. 16. The composite particles are magnetic particles, or
Magnetic particles and non-magnetic particles are 60 to 99 based on composite particles.
2. The composition according to claim 1, wherein the content is in the range of 1% by mass.
5. The method for producing magnetic particle-dispersed composite particles according to any one of 5. 17. The method for producing magnetic particle-dispersed composite particles according to claim 11, wherein the composite particles are further coated with an organic compound. 18. The method according to claim 17, wherein the organic compound contains at least a reactive coupling agent.
3. The method for producing magnetic particle-dispersed composite particles according to 1.). 19. The composite particles having a 50% average particle size of 5 to 5.
The thickness is 100 μm.
The method for producing magnetic particle-dispersed composite particles according to any one of the above. 20. The binder resin according to claim 11, wherein the binder resin is obtained by reacting a phenol and an aldehyde with a tertiary amine as a catalyst and further adding an ammonia catalyst. A method for producing magnetic particle-dispersed composite particles according to the above item (1).