JP4378210B2 - Magnetic fine particle dispersed resin carrier and two-component developer - Google Patents

Description

  The present invention relates to a two-component developing method for developing and developing an electrostatic latent image formed on an electrostatic latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording derivative in electrophotography. The present invention relates to an improvement in a magnetic fine particle dispersed resin carrier used in a developing device to which is applied. The present invention also relates to a two-component developer having the magnetic fine particle dispersed resin carrier.

  Conventionally, a number of methods are known as electrophotography, but generally an electro latent image is formed on an electrostatic latent image carrier (photosensitive drum) by using a photoconductive substance by various means. Subsequently, the electrostatic latent image is developed with a developer to form a toner image to be visualized, and the toner image is transferred to a transfer material such as paper as necessary, and then transferred to the transfer material by heat, pressure, or the like. A toner image is fixed on top to obtain a copy. The development method in electrophotography is mainly divided into a one-component development method that does not require a carrier and a two-component development method that uses a toner and a carrier. In particular, in a full-color copying machine or full-color printer that requires high image quality, A two-component development method is preferably used.

  As a two-component development method, a magnetic brush of a two-component developer having a nonmagnetic toner and a magnetic carrier is formed on a developing sleeve containing a magnet, and the magnetic brush is subjected to a predetermined development by a developer layer thickness regulating member. After the thickness of the agent layer is reached, the magnetic brush is conveyed to a developing area facing the photosensitive drum, and the magnetic brush is exposed to light while applying a predetermined developing bias between the photosensitive drum and the developing sleeve. A method is known in which the electrostatic latent image is visualized as a toner image by being brought close to or in contact with the drum surface.

  Examples of the magnetic carrier used in such a two-component developer include an iron powder carrier, a ferrite carrier, or a magnetic fine particle dispersed resin carrier in which magnetic fine particles are dispersed in a binder resin. In the iron powder carrier, since the resistivity of the carrier itself is low, the charge of the electrostatic latent image leaks through the carrier, and the electrostatic latent image may be disturbed, thereby causing an image defect. Also, in ferrite carriers, although the carrier itself has a relatively high resistivity, the magnetic brush tends to become stiff due to its large saturation magnetization, and the magnetic brush has uneven spots on the toner image. There is.

  In order to solve such a problem, a magnetic fine particle-dispersed resin carrier in which magnetic fine particles are dispersed in a binder resin is preferably used (for example, see Patent Document 1). The magnetic fine particle-dispersed resin carrier has a relatively higher resistivity than a ferrite carrier, has a small saturation magnetization, and a low true specific gravity, thus preventing electrostatic latent image charge leakage and a rigid magnetic brush. Therefore, it is possible to form a good toner image free from image defects and unevenness in the stitches.

  In a two-component developer using an iron powder carrier or a ferrite carrier, a part of toner particles is generated by a mechanical collision such as a collision between particles and a collision between the particle and the inside of the developing device, or heat generated by the collision. There is a case where a so-called spent phenomenon occurs in which the film physically adheres to the surface of the film to form a film. When this phenomenon occurs, a film of toner components gradually accumulates on the carrier surface, and the triboelectric charge between the carrier and the toner particles is replaced with the triboelectric charge between the toner particles. As a result, the triboelectric charging characteristics of the entire agent deteriorate, and as a result, so-called background smearing occurs in which a large amount of toner adheres to the background portion of the copy image, and the copy quality may deteriorate. Furthermore, if the spent becomes significant, the entire developer needs to be replaced, which may increase the cost.

  On the other hand, the above-described magnetic fine particle dispersed resin carrier has a small saturation magnetization and a small true specific gravity, which is advantageous for the spent as described above. Magnetic fine particle-dispersed resin carriers are relatively easy to make spherical shapes with little particle distortion and high particle strength, so they have excellent fluidity and control the particle size over a wide range. Therefore, it is expected to be applied to high-speed copying machines and high-speed laser beam printers. Further, a proposal has been made to prevent toner spent by coating the surface of a magnetic fine particle dispersed carrier with a resin having an aminosilane coupling agent, a fluoroalkyl unit, a methylene unit, or the like (see, for example, Patent Document 2).

  However, the magnetic fine particle dispersed resin carrier, when trying to cope with high speed copying such as a high-speed copying machine or a high-speed laser beam printer, causes the carrier to adhere to the photosensitive member because of its low magnetic force. May be disturbed.

In the magnetic fine particle dispersed resin carrier, magnetite is often used as the magnetic fine particle from the viewpoint of versatility and cost. However, if the magnetite content is increased in order to increase the magnetic force, the resistivity is reduced. Low magnetite is likely to be present on the carrier surface, causing electrostatic latent image charge leakage, increasing the residual magnetization of the carrier, reducing the fluidity of the developer, and increasing the magnetic force of the magnetite. Dispersion in the carrier due to magnetic aggregation is reduced, resulting in variations in the physical properties between the carriers and non-uniform toner charge distribution, resulting in high density and excellent dot reproducibility. May become impossible.
If the content of magnetite is reduced, the resistivity as a carrier increases, but the carrier adheres to the photoconductor due to the decrease in magnetic force as described above, and the carrier is insulated and works as a developing electrode during development. Therefore, an edge effect is generated between halftone and solid black, so that a so-called white spot phenomenon is likely to occur, and an image defect may occur.

On the other hand, a magnetic carrier using magnetic fine particles having high fluidity while maintaining a magnetic force has been proposed (see, for example, Patent Document 3). However, the balance between the residual magnetization and fluidity of the magnetic carrier itself is sufficient, but the resistivity and saturation magnetization are still insufficient. In order to further improve the above problems, a magnetic carrier having a high resistivity and saturation magnetization while maintaining a balance between residual magnetization and fluidity is desired.
JP-A-9-281807 JP 2000-39740 A JP 2002-328493 A

  The object of the present invention is to prevent leakage of charges to the electrostatic latent image, unevenness of the marks on the toner image, spent on the toner carrier, and no carrier adhesion on the photosensitive member due to higher speed, An object of the present invention is to provide a magnetic fine particle-dispersed resin carrier capable of forming a good image without white spots or the like.

  Another object of the present invention is to use the above-mentioned magnetic fine particle dispersed resin carrier to obtain a two-component development capable of obtaining an image having high density and excellent dot reproducibility over a long period of time even in different environments. Is to provide an agent.

In the magnetic fine particle-dispersed resin carrier, the inventors set the resistivity of the magnetic fine particles within a specific range while maintaining the residual magnetization and fluidity of the carrier, thereby reducing the electric resistance and saturation magnetization as the carrier. It was found that it could be improved, leading to the present invention.
That is, the present invention is as follows.
(1) In a magnetic carrier having a magnetic fine particle dispersed resin core containing at least magnetic fine particles and a binder resin, and a coating layer covering the surface of the magnetic fine particle dispersed resin core,
The resistivity of the magnetic fine particles Ri ^{1 × 10 6 ~1 × 10 10} Ω · cm der,
The magnetic fine particles contain Fe and at least one of Mg component, Ca component, Ti component and Zn component, and the total amount in terms of each element is 0.3 to 4.0% by mass with respect to the total Fe amount. A magnetic fine particle-dispersed resin carrier.
(2) The magnetic fine particle has a ratio B (% by mass) of Fe ^{2+ to} the total amount of Fe in 10% by mass from the surface, and a ratio C (% by mass) of Fe ^{2+ to} the total amount of Fe in the remaining 90% by mass. The magnetic fine particle-dispersed resin carrier according to (1) , wherein the ratio satisfies the following formula (1):
0.3 ≦ B / C <1.0 (1)
(3) The ratio A (mass%) of Fe ²⁺ with respect to the total Fe amount in the magnetic fine particle-dispersed carrier satisfies the following formula (2), and the resistivity is 1 × 10 ⁷ to 1 × 10 ¹¹ Ω · cm. (1) or (2) the magnetic fine particle dispersed resin carrier,
5.0 ≦ A ≦ 30 (2)
(4) In a two-component developer containing a toner and a magnetic carrier,
The toner contains at least a binder resin, a colorant, and a release agent, and has a weight average particle size of 3.0 to 9.0 μm.
The two-component developer, wherein the magnetic carrier is a magnetic fine particle dispersed resin carrier of any one of (1) to (3) .
(5) the binder resin contains at least a polyester unit, wherein the average circularity of particles in the circle equivalent diameter 2μm or more toner in the toner is characterized in that it is 0.920 or more 0.970 (4) below Two-component developer.

  According to the present invention, it is possible to provide a magnetic carrier capable of improving the electrical resistance and saturation magnetization as a carrier while maintaining the residual magnetization and fluidity of the carrier.

  The two-component developer using the magnetic carrier, when used for image formation, can prevent leakage of charge to the electrostatic latent image, unevenness of the marks on the toner image, and spent of the toner on the carrier, and There is no carrier adhesion on the photoconductor due to the increase in speed, and it is possible to form a good image with high density and excellent dot reproducibility without white spots. Further, the two-component developer of the present invention can remarkably improve transferability and cleaning properties while maintaining good toner chargeability and fixability.

Hereinafter, the best mode for carrying out the present invention will be described in detail.
The magnetic fine particle dispersed resin carrier of the present invention has a magnetic fine particle dispersed resin core in which magnetic fine particles are dispersed in a binder resin. Prevents leakage of electrostatic latent image charge, unevenness of toner image, and toner spent on carrier particles, and does not cause carrier adhesion to the photoconductor due to higher speeds. In order to obtain a good image with excellent dot reproducibility, the electric characteristics and magnetic characteristics of the magnetic fine particles in the magnetic fine particle dispersed resin core are greatly involved. Conventionally, the magnetic fine particles have low electric resistance, so that the resistance adjustment and magnetic force adjustment as a magnetic fine particle-dispersed resin carrier have been performed by the combined use with non-magnetic fine particles. The inventors have found that the above-mentioned problems can be solved by improving the electrical resistance of the magnetic carrier by maintaining a high resistance and maintaining the magnetic characteristics and fluidity, and have reached the present invention.

The magnetic fine particle dispersed resin carrier of the present invention has a magnetic fine particle dispersed resin core containing at least magnetic fine particles and a binder resin, and a coating layer covering the surface of the magnetic fine particle dispersed resin core. The magnetic fine particles in the resin core have a resistivity of 1 × 10 ⁶ to 1 × 10 ¹⁰ Ω · cm. When the resistivity of the magnetic fine particles satisfies the above range, the electric resistance can be improved without lowering the saturation magnetization as a carrier, and the carrier leaks to the photoconductor due to the leakage of charge of the electrostatic latent image and the increase in speed. Therefore, it is possible to obtain a good image with high density and excellent dot reproducibility without white spots. If the resistivity of the magnetic fine particles is lower than 1 × 10 ⁶ Ω · cm, the resistivity as a carrier is lowered, so that the electrostatic latent image is liable to leak electric charges and may cause image defects. On the other hand, if the resistivity of the magnetic fine particles is higher than 1 × 10 ¹⁰ Ω · cm, the resistivity as a carrier is increased, so that image defects such as white spots are likely to occur.

  The magnetic fine particles used in the magnetic fine particle-dispersed resin carrier of the present invention contain at least one of Mg, Ca, Ti, and Zn components, and the total amount in terms of each element is based on the total Fe amount. Magnetite particles containing 0.3 to 4.0% by mass are preferred. By using magnetite particles with controlled distribution and total amount of Mg component, Ca component, Ti component, and Zn component as magnetic fine particles of magnetic fine particle type resin carrier, electric resistance can be improved without deteriorating magnetic properties as a carrier. Moreover, since the magnetic aggregation between the magnetic fine particles can be suppressed, the fluidity as a carrier can be remarkably improved.

When the total amount in terms of each element is less than 0.3%, the improvement effect on the electric resistance and fluidity of the magnetite particles tends to be small. On the other hand, when it exceeds 4.0% by mass, although the electric resistance and fluidity are sufficiently improved, the magnetic properties of the magnetite particles are likely to be lowered.
The magnetite particles preferably contain at least one or more additive elements of Mg, Ca, Ti, and Zn other than Fe on the surface rather than inside the magnetite particles. If it is not exposed on the surface of the magnetite particles, the effect of improving the electric resistance and fluidity of the magnetite particles may not be obtained.

  Therefore, at least one or more additive elements of Mg, Ca, Ti, and Zn other than Fe must be contained before the crystals of magnetite particles are formed. And, in order to increase the content of additive elements other than Fe on the surface of the magnetite particles, for example, there is a method of adjusting the addition time, precipitation temperature, and pH of additive elements other than Fe at the time of magnetite crystal generation, It is not limited to those methods. The magnetite particles thus obtained have significantly improved electric resistance and fluidity of the magnetite particles compared with those in which at least one additional element of Mg, Ca, Ti, Zn other than Fe is not added. However, when it is used in a magnetic fine particle dispersed resin carrier, the performance of the carrier can be exhibited more effectively.

  In addition, other than the above-described additive elements can be used as the at least one additive element among Mg, Ca, Ti, and Zn other than Fe. For example, the total amount including at least one selected from Si, P, S, Cr, Co, Ni, Cu and the above-described additive elements is 0.3 to 4.0% by mass with respect to the total Fe amount. It is preferable to make it contain.

Below, the preferable manufacturing method of the magnetite particle | grains which can be used as a magnetic fine particle in this invention is demonstrated.
The magnetite particles that can be used in the present invention are prepared by oxidizing a ferrous hydroxide slurry obtained by neutralizing and mixing a ferrous salt aqueous solution and an alkali solution to produce magnetite particles. A ferrous hydroxide slurry obtained by adding and mixing a compound containing each elemental component such as Mg, Ca, Ti, and Zn to a ferrous salt aqueous solution adjusted to a predetermined pH and temperature. It can be manufactured by using it.
What can be utilized as a ferrous salt will not be specifically limited if it is a salt soluble in water, such as ferrous sulfate and ferrous chloride. In addition, those that can be used as compounds containing each elemental component other than Fe, such as Mg, Ca, Ti, and Zn, are sulfates and chlorides that cause hydrolysis in ferrous salt aqueous solution and do not precipitate as hydroxides. , Selected from nitrates and the like.
The amount of the alkaline solution in producing the ferrous hydroxide slurry is appropriately determined according to the content necessary for the surface of the magnetite particles, such as Mg, Ca, Ti, Zn other than Fe, and the shape of the magnetite particles to be obtained. adjust.
As the alkaline solution, an alkali hydroxide aqueous solution such as sodium hydroxide or potassium hydroxide aqueous solution can be used.

The magnetite particles that can be used in the present invention may be any particles such as spherical, hexahedral, octahedral, polyhedral, etc., as long as they are granular particles, but they are spherical from the viewpoint of dispersibility in the carrier. Is more preferable.
Using the ferrous hydroxide slurry thus obtained, an oxidation reaction is performed while blowing a conventional oxygen-containing gas, preferably air, into the slurry, and the slurry after completion of the oxidation reaction is filtered, washed and dried by a conventional method. Then, pulverization is performed to obtain magnetite particles.

The magnetic fine particles that can be used in the present invention are preferably the above-mentioned magnetite particles. Furthermore, the ratio of the ratio B (% by mass) of Fe ^{2+ to} the total amount of Fe in 10% by mass from the surface of the magnetic fine particle and the ratio C (% by mass) of Fe ^{2+ to} the total amount of Fe in the remaining 90% by mass, It is preferable that the following formula (1) is satisfied.
0.3 ≦ B / C <1.0 (1)
By setting the B / C ratio of the magnetic fine particles in the above range, the resistivity can be improved without lowering the saturation magnetization as a carrier, and the magnetic aggregation between the magnetic fine particles in the carrier is suppressed, The dispersibility of the magnetic fine particles in the carrier is improved, thereby preventing variations in physical properties between the carrier particles. Further, when the resistivity and B / C ratio of the magnetic fine particles satisfy the above ranges, when the magnetic fine particle dispersed resin carrier is used as a two-component developer, the charge distribution of the toner can be further sharpened. By improving the strength of the toner and improving the durability of the developer, a good image can be obtained over a long period of time.

When the B / C ratio of the magnetic fine particles is less than 0.3, it cannot be said that the ratio of Fe ²⁺ near the surface of the magnetic fine particles is sufficient, and the electric resistance as a carrier is high, but the magnetic characteristics tend to deteriorate. When a magnetic fine particle-dispersed resin carrier containing magnetic fine particles having a B / C ratio of less than 0.3 is used for image formation as a two-component developer, carrier adhesion may occur on the photoreceptor. In addition, when the B / C ratio of the magnetic fine particles is 1.0 or more, although the magnetic characteristics are improved, the electrical resistance is lowered, the magnetic aggregation between the magnetic fine particles is deteriorated, the charge leakage and the magnetic fine particles in the carrier There is a tendency for the dispersibility of the to decrease.
As magnetic fine particles satisfying 0.3 ≦ B / C <1.0, magnetite particles obtained by the above production method may be used.

In the magnetic fine particle-dispersed resin carrier of the present invention, the ratio A (mass%) of Fe ²⁺ with respect to the total Fe amount in the carrier satisfies the following formula (2), and the resistivity is 1 × 10 ⁷ to 1 × 10 ^11. (Ω · cm) is preferable.
5.0 ≦ A ≦ 30 (2)

By making the ratio of Fe ^{2+ to} the total Fe amount in the magnetic fine particle dispersed resin carrier and the resistivity of the carrier within the above ranges, when used for image formation as a two-component developer, the charge on the electrostatic latent image is reduced. Leakage, unevenness in the toner image, and spent toner on the carrier can be prevented, and there is no carrier adhesion on the photoconductor due to high speed, high density without white spots and excellent dot reproducibility. A good image can be formed.

When the ratio of Fe ^{2+ to} the total amount of Fe in the carrier exceeds 30% by mass, when the two-component developer is used in the magnetic brush developing method, the magnetic force becomes too high and the magnetic brush becomes stiff, and the postscript There are cases where unevenness of eyes occurs or toner spent is accelerated as the durability progresses. Further, when the Fe ²⁺ ratio is less than 5% by mass, when the two-component developer is used for image formation, the magnetic force becomes too small to cause the carrier to adhere to the photoreceptor, and the resistivity as the carrier is also low. Since it becomes high, white spots are likely to occur, and the image quality may be disturbed. From the above, in the magnetic fine particle dispersed resin carrier of the present invention, the ratio of Fe ^{2+ to} the total Fe amount in the carrier is 5.0% by mass or more and 30% by mass or less, particularly preferably 10% by mass or more. 25% by mass or less.

Further, when the resistance of the magnetic fine particle dispersed resin carrier is less than 1 × 10 ⁷ Ω · cm, white spots are improved when used as an image forming agent as a two-component developer, but the electrostatic latent image of minute dots is improved. The image is disturbed and the halftone reproducibility tends to be inferior. In addition, when the resistivity of the magnetic fine particle dispersed resin carrier exceeds 1 × 10 ¹¹ Ω · cm, white spots are deteriorated, and developability sufficiently satisfying the latent image potential cannot be obtained, and an image is not obtained. It may get worse.

The magnetic fine particles used in the present invention preferably have a specific surface area by the BET method of 2.0 to ²⁰ m ² / g. By being in this range, the dispersibility of the magnetic fine particles in the magnetic fine particle dispersed resin carrier is further improved, and the uniform dispersibility of the magnetic fine particles on the surface of the magnetic fine particle dispersed resin carrier is improved. Accordingly, the fluidity of the carrier is good, the toner charge distribution can be further sharpened, and the strength of the carrier can be further improved, so that the durability of the two-component developer can be further improved. .

When the BET value of the magnetic fine particles is less than 2.0 m ² / g, it becomes difficult to encapsulate in the carrier, the magnetic fine particle-dispersed resin carrier surface becomes uneven, the carrier fluidity is remarkably lowered, and the toner charging The distribution may become non-uniform.
When the BET value of the magnetic fine particles exceeds 20 m ² / g, the surface area of the magnetic fine particles becomes too large, magnetic aggregation of the magnetic fine particles deteriorates, and the dispersibility of the magnetic fine particles in the magnetic fine particle dispersed resin carrier deteriorates. As a result, variations in physical properties between carriers may increase.

The magnetic fine particles used in the magnetic fine particle-dispersed resin carrier of the present invention have a magnetization strength (σ1000) of 50 to 200 Am ² / kg under a magnetic field of 1000 × (10 ³ / 4π) · A / m (1000 oersted) ( It is preferably 50 to 100 Am ² / kg) and a residual magnetization (σr) of ² to 20 Am ² / kg (preferably ^{2 to} 10 Am ² / kg).
The magnetic fine particles used in the magnetic fine particle-dispersed resin carrier of the present invention can be used after being subjected to a high resistance treatment by a known method such as a consolidation treatment. This consolidation treatment or the like is preferably used because it is possible to increase the electrical resistance of the magnetic fine particles under conditions that do not deteriorate the magnetic properties.

The magnetic fine particles used in the magnetic fine particle dispersed resin carrier of the present invention may be subjected to a coupling treatment with a coupling agent. As a coupling treatment agent, 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, a halogenated alkyl group and an aldehyde group And mixtures thereof, any of which can achieve the object of the present invention. Of these, a silane coupling agent, a titanium coupling agent or an aluminum coupling agent is preferable, and a silane coupling agent is particularly preferable. Furthermore, a coupling agent having an epoxy group, an amino group or a mercapto group as a preferred functional group is preferable because the magnetic fine particles are easily dispersed uniformly in the magnetic fine particle dispersed resin carrier, and further, a coupling agent having an epoxy group. However, it is preferable in that it is hardly affected by temperature and humidity and the charge imparting ability of the carrier is stabilized.

The amount of magnetic fine particles used in the magnetic fine particle dispersed resin carrier of the present invention is 70 to 95% by mass, more preferably 80 to 92% by mass, based on the magnetic fine particle dispersed resin carrier. It is preferable for reducing the true specific gravity of the resin carrier and ensuring sufficient mechanical strength.
Further, in order to adjust the magnetic properties and true specific gravity of the magnetic fine particle dispersed resin carrier, the magnetic fine particle dispersed resin carrier particles may further contain nonmagnetic inorganic compound fine particles in addition to the magnetic fine particles. When magnetic fine particles and further nonmagnetic inorganic compound fine particles are contained, due to the difference in magnetic properties and true specific gravity between the nonmagnetic inorganic compound fine particles and the magnetic fine particles, it is necessary that the dispersibility in the carrier particles is not uniform between the carrier particles. Select the one that makes the dispersibility of both fine particles uniform in the carrier particles because the dispersion of the physical properties of the particles may occur or the carrier particle shape may not be spherical. Is preferred.

The magnetic fine particles are preferably contained in an amount of 50 to 100% by mass with respect to the total amount of the magnetic fine particles and the nonmagnetic inorganic compound fine particles in order to adjust the magnetization strength and resistivity of the magnetic fine particle dispersed resin carrier. Furthermore, it is preferable that 70-100 mass% of magnetic fine particles are contained with respect to the total amount of magnetic fine particles and nonmagnetic inorganic compound fine particles.
In the magnetic fine particle-dispersed resin carrier of the present invention, the magnetic fine particles are preferably the above-mentioned magnetite fine particles, and hematite (α-Fe ₂ O ₃ ) fine particles are used as the non-magnetic inorganic compound fine particles. You may use together in order to adjust specific gravity.

The magnetic fine particle dispersed resin carrier of the present invention is formed by coating the surface of a magnetic fine particle dispersed resin core (hereinafter also referred to as “core”) containing at least the magnetic fine particles and the binder resin with a coating material. It has a coating layer. The binder resin constituting the core in the present invention is preferably a thermosetting resin.
Thermosetting resins include phenolic resins, epoxy resins, polyamide resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, xylene resins, acetoguanamine resins, furan resins, silicone resins, polyimide resins, urethane resins. Etc. These resins may be used alone or in combination of two or more, but preferably contain at least a phenol resin.

  The ratio of the binder resin and magnetic fine particles (and non-magnetic fine particles) constituting the core in the present invention is, based on mass, binder resin: magnetic fine particles (and non-magnetic fine particles) = 1: 99 to 1:50. preferable.

  As the binder resin used for the coating layer of the magnetic fine particle-dispersed resin carrier of the present invention, any known resin can be used. Preferably, polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, Perfluoropolymers such as polyfluorochloroethylene, polytetrafluoroethylene, polyperfluoropropylene, copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and trifluorochloroethylene, tetrafluoro Examples thereof include a copolymer of ethylene and hexafluoropropylene, a copolymer of vinyl fluoride and vinylidene fluoride, and a copolymer of vinylidene fluoride and tetrafluoroethylene.

  In particular, the binder resin for forming the coating layer preferably used in the present invention is preferably a (meth) acrylic acid ester polymer or copolymer having a perfluoroalkyl unit represented by the following formula (3).

(In the formula, m represents an integer of 0 to 11.)

The polymer or copolymer of the (meth) acrylic acid ester having a perfluoroalkyl unit represented by the above formula (3) can be used alone, but the polymer or copolymer may be mixed and used. Good. In addition, a curing agent or the like can be mixed with a thermoplastic resin and cured for use.
In the above formula (3), when m exceeds 11, the resin is likely to precipitate from the solvent, and when a coating layer is formed using the coating material, it is difficult to obtain a good coating layer. In particular, it is more preferable that m is 5 to 9 because when the carrier is used as a two-component developer, it has both good toner releasability and coat film formation.

  Furthermore, it is preferable to use a polymer or copolymer of (meth) acrylic acid ester having a unit represented by the following formula (4) as the binder resin of the coating layer because of excellent adhesion to the core.

(In the formula, m represents an integer of 0 to 11, and n represents an integer of 1 to 10.)

  In particular, a polymer or copolymer of a (meth) acrylic acid ester having a unit represented by the following formula (5) and a (meth) acrylic acid ester unit represented by the following formula (6) is used as a magnetic fine particle dispersed resin carrier. It is preferable to use it for the coating layer in order to improve the toner releasability from the carrier.

(In the formula, m represents an integer of 0 to 11, n represents an integer of 1 to 10, and l represents an integer of 1 or more.)

（式中、Ｒ₁は水素又はメチル基を有し、Ｒ₂は水素又は炭素数１〜２０のアルキル基を示し、ｋは１以上の整数を示す。）

(Wherein R ₁ has hydrogen or a methyl group, R ₂ represents hydrogen or an alkyl group having 1 to 20 carbon atoms, and k represents an integer of 1 or more.)

Even if the resin obtained by graft polymerization of the unit represented by the above formula (6) on the polymer or copolymer having the units represented by the above formulas (5) and (6) has a toner releasability characteristic even when used for a long time. This is particularly preferable because it can be maintained and the coating layer is difficult to peel off from the core and has excellent peel resistance.
When a thermoplastic resin is used as the binder resin for forming the coating layer, this thermoplastic resin has a weight average molecular weight of 10,000 in a gel permeation chromatograph (GPC) of a soluble component of tetrahydrofuran (THF). It is preferable that it is -300,000 at the point which improves the intensity | strength of a coating layer, and the peeling resistance of a coating layer and a core surface.

  The binder resin forming the coating layer preferably has a main peak in the region of molecular weight 2,000 to 100,000 in the GPC chromatogram of the THF soluble component, and further has a molecular weight of 2,000 to 100,000. It is preferable to have a subpeak or shoulder in the region of 000. Most preferably, the resin forming the coating layer has a main peak in the molecular weight range of 20,000 to 100,000 in the GPC chromatogram of the THF soluble component, and a molecular weight range of 2,000 to 19,000. It is preferable to have sub-peaks or shoulders. By satisfying the above molecular weight distribution, development durability that enables development of a large number of sheets even with a small particle size toner, charging stability to the toner, and prevention of adhesion of external additives to the carrier surface are further improved. To do.

When the binder resin forming the coating layer is a graft polymer, the graft polymer has a trunk weight average molecular weight of 15,000 to 200,000 and a branch weight average molecular weight of 3,000 to It is preferable that it is 10,000. The weight average molecular weight can be adjusted by the polymerization conditions of the trunk portion of the graft polymer and the polymerization conditions of the branch portion of the graft polymer.
In the present invention, it is particularly preferable to use a resin having a graft polymer as a coating material for forming a coating layer because of excellent peeling resistance from the core surface of the coating layer.

  In the present invention, a silicone resin can also be used as the binder resin for forming the coating layer from the viewpoint of adhesion to the core and prevention of spent. The silicone resin can be used alone, but it is preferably used in combination with a coupling agent in order to increase the strength of the coating layer and control the charge to a preferable level. Furthermore, the above-mentioned coupling agent is preferably used as a so-called primer agent in which a part of the coupling agent is treated on the surface of the carrier core before coating the silicone resin, and the subsequent coating layer has a covalent bond. It can be formed in a highly adhesive state.

As the coupling agent, aminosilane is preferably used. As a result, a positively charged amino group can be introduced on the surface of the carrier, and the toner can be favorably imparted with negative charging characteristics. Furthermore, in the case of magnetic fine particle dispersed resin carrier, the presence of amino groups activates both the coupling agent and the silicone resin that are preferably used for the treatment of the magnetic fine particles, so that the adhesion of the silicone resin to the carrier core is further increased. And at the same time, the curing of the resin can be promoted, so that a stronger coating layer can be formed.

The coating treatment of the coating layer is preferably performed under a reduced pressure at a temperature of 30 to 80 ° C. The reason is not clear, but is expected to be described below.
(I) A moderate reaction proceeds at the coating stage, and the coating material is uniformly and smoothly coated on the surface of the carrier core.
(Ii) In the baking step, a low temperature treatment at at least 160 ° C. is possible, and excessive crosslinking of the resin can be prevented and the durability of the coating layer can be enhanced.

  It is preferable that the coating amount with respect to the core of the coating material for forming the coating layer is 0.3 to 4.0 parts by mass with respect to 100 parts by mass of the core. Preferably, it is 0.4-3.5 mass parts, More preferably, it is 0.5 mass part-3.2 mass parts.

  When a magnetic fine particle dispersed resin carrier in the above range is used for a two-component developer, good toner separation properties can be obtained, and image defects such as white spots are unlikely to occur. If the amount is less than 0.3 parts by mass, the core surface cannot be sufficiently coated, and the effects of the present invention are hardly exhibited. On the other hand, when the amount exceeds 4.0 parts by mass, uniform coating cannot be performed at the time of coating, and charge up and the core surface may be exposed, resulting in toner spent at that portion. In addition, the resistivity of the magnetic fine particle dispersed carrier is increased, and image defects such as white spots may occur.

The coating layer preferably contains fine particles in order to further uniform the shape of the carrier surface and / or to sharpen the charge distribution of the toner.
As the fine particles, either organic or inorganic fine particles can be used. However, it is necessary to maintain the shape of the fine particles when the coating layer is formed by coating the core with a coating material. Inorganic fine particles can be preferably used. Specifically, the crosslinked resin fine particles include crosslinked polymethyl methacrylate resin fine particles, crosslinked polystyrene resin fine particles, melamine resin fine particles, phenol resin fine particles, nylon resin fine particles, etc., and inorganic fine particles include silica fine particles, titanium oxide fine particles, And alumina fine particles, and the like can be used alone or in combination. Among these, crosslinked polymethylmethacrylate resin fine particles, crosslinked polystyrene resin fine particles, and melamine resin fine particles are preferable from the viewpoint of charging stability.

  These fine particles are preferably used in an amount of 1 to 40 parts by mass with respect to 100 parts by mass of the binder resin used for the coating layer. By using it in the above range, charging stability and toner separation can be improved, and image defects such as white spots can be prevented. When the amount is less than 1 part by mass, the effect of addition of fine particles cannot be obtained, and when the amount exceeds 40 parts by mass, lack from the coating layer occurs during durability, and the durability tends to be inferior.

  The particle diameter of the fine particles used in the coating layer is preferably 0.08 to 0.70 μm (more preferably 0.10 to 0.50 μm) in terms of number average particle diameter in order to improve toner separation. When the thickness is less than 0.08 μm, it is difficult to disperse the fine particles in the coating layer. When the thickness exceeds 0.70 μm, the particles are missing from the coating layer during durability, and the durability tends to be poor.

The coating layer preferably contains conductive fine particles so as not to lower the resistivity of the magnetic fine particle dispersed resin carrier excessively and to remove residual charges on the carrier surface.
The conductive fine particles preferably have a resistivity of 1 × 10 ⁸ Ω · cm or less, and more preferably 1 × 10 ⁶ Ω · cm or less. Specifically, it is preferable to contain at least one kind of conductive fine particles selected from carbon black, magnetite, graphite, titanium oxide, alumina, zinc oxide, and tin oxide. In particular, carbon black is preferably used as the conductive fine particles because the residual charge on the carrier surface can be removed with a small addition amount, and the unevenness due to the fine particles on the carrier surface is not hindered. . The carbon black has a number average particle size of 10 to 60 nm, more preferably 15 to 50 nm, in order to remove residual charges on the carrier surface and prevent detachment from the carrier. Is preferred.

The DBP oil absorption amount of carbon black is preferably 20 to 500 ml, more preferably 25 to 300 ml, particularly preferably 30 to 200 ml, based on 100 g of carbon black.
When the DBP oil absorption is in the above range, the residual charge on the carrier surface is efficiently removed, which is preferable in controlling the charge of the carrier. If it is less than 20 ml / 100 g, the structure of carbon black is short, so that efficient charge removal is not performed, and the effect of addition is hardly exhibited.

  These conductive fine particles are used in an amount of 1 to 15 parts by mass with respect to 100 parts by mass of the binder resin of the coating layer, so that the resistivity of the carrier is not lowered too much and the residual charge on the carrier surface is efficiently removed. This is preferable. When the amount is less than 1 part by mass, the effect of removing the residual charge on the carrier surface is hardly exhibited. When the amount exceeds 15 parts by mass, dispersion in the coating layer becomes unstable, and excessive charge removal effect is exhibited. Therefore, the charge imparting ability of the carrier itself may be reduced.

  The magnetic fine particle dispersed resin carrier of the present invention preferably has a number average particle size of 10 to 80 μm. If the number average particle diameter is less than 10 μm, the amount of magnetization per carrier particle becomes small, and carrier adhesion to the photoreceptor may easily occur. On the other hand, if the thickness exceeds 80 μm, the specific surface area of the toner may be small, and good charging may not be achieved. In order to improve image quality and prevent carrier adhesion, it is preferably 15 to 60 μm, particularly preferably 20 to 45 μm.

The magnetic fine particle dispersed resin carrier of the present invention has a size of 1000 × (10 ³ / 4π) · A / m (1
000 oersted), the magnetization intensity (σ1000) measured under a magnetic field of 15 to 80 Am ²
/ Kg (emu / g), and the residual magnetization (σr) is preferably 10 Am ² / kg or less. When the strength of magnetization (σ1000) exceeds 80 Am ² / kg, the stress on the toner increases in the magnetic brush when the magnetic fine particle dispersed resin carrier is used in the magnetic brush developing method as a two-component developer. In addition, the toner may deteriorate and the spent on the carrier may easily occur. Further, when the magnetization strength (σ1000) is less than 15 Am ² / kg, the magnetic binding force to the developing sleeve is lost, and the carrier adheres and adheres to the surface of the photoconductor to cause a defect in the image. Further, when the remanent magnetization (σr) exceeds 10 Am ² / kg, poor fluidity may occur due to magnetic aggregation.

The true specific gravity of the magnetic fine particle dispersed resin carrier of the present invention is preferably 2.5 to 4.5 g / cm ^3, more preferably 3.0 to 4.0 g / cm ³ . When the true specific gravity of the magnetic fine particle dispersed resin carrier is within this range, the load on the toner is small in the stirring and mixing of the magnetic fine particle dispersed resin carrier and the toner, the toner spent on the carrier is suppressed, and the photoconductor This is preferable because carrier adhesion is suppressed.

The method for producing the magnetic fine particle dispersed resin core in the present invention is as follows. A monomer constituting the binder resin and magnetic fine particles satisfying the physical properties such as resistivity, Fe ²⁺ content ratio, and content of elements other than Fe are mixed, and the monomer is polymerized to obtain magnetic fine particle dispersed core particles. At this time, as monomers used for polymerization, vinyl monomers, bisphenols and epichlorohydrin for forming epoxy resins; phenols and aldehydes for forming phenol resins; urea and aldehydes for forming urea resins Melamine and aldehydes; Specifically, for example, as a method for producing magnetic fine particle-dispersed core particles using a curable phenol resin, magnetic fine particles are placed in an aqueous medium, and phenols and aldehydes are polymerized in the presence of a basic catalyst in the aqueous medium. There is a method of obtaining a magnetic fine particle dispersed core.

  Other methods for producing a magnetic fine particle dispersed resin core include mixing a vinyl or non-vinyl thermoplastic resin, magnetic fine particles, and other additives with a mixer before heating rolls, kneaders, extruders, etc. There is a method in which a magnetic fine particle dispersed core is obtained by melting and kneading using a kneading machine, cooling this, and then pulverizing and classifying. At this time, it is preferable to thermally or mechanically spheroidize the obtained magnetic fine particle dispersed core and use it as a magnetic fine particle dispersed core for the magnetic fine particle dispersed resin carrier of the present invention. As the binder resin used at this time, a thermosetting resin such as a phenol resin, a melamine resin, or an epoxy resin is preferable in terms of excellent charging property, durability, impact resistance, and heat resistance. The binder resin is more preferably a phenol resin from the viewpoint of dispersibility of the magnetic fine particles in the carrier particles and handling properties in order to more suitably express the characteristics of the present invention.

  Phenols as monomers for producing a phenol resin include, in addition to phenol itself, alkylphenols such as m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol, bisphenol A, and benzene nuclei of these compounds. Or the compound which has phenolic hydroxyl groups, such as halogenated phenols by which one part or all part of the alkyl group was substituted by the chlorine atom or the bromine atom is mentioned. Of these, phenol (hydroxybenzene) is more preferable.

Examples of aldehydes as monomers for producing a phenol resin include formaldehyde and furfural in the form of either formalin or paraaldehyde. Of these, formaldehyde is particularly preferable.
The molar ratio of aldehydes to phenols is preferably 1 to 4, particularly preferably 1.2 to 3. When the molar ratio of aldehydes to phenols is less than 1, the core is difficult to produce, and even if it is produced, the resin does not easily cure, so the strength of the produced core tends to be weak. On the other hand, when the molar ratio of aldehydes to phenols is larger than 4, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

  A basic catalyst is used when polycondensation of phenols and aldehydes, and a basic catalyst used for production of a normal resol type resin may be used. Examples of such a basic catalyst include aqueous ammonia, hexamethylenetetramine, and alkylamines such as dimethylamine, diethyltriamine, and polyethyleneimine. The molar ratio of these basic catalysts to phenols is preferably 0.02 to 0.3.

  The magnetic fine particle dispersed resin carrier of the present invention is obtained by forming a coating layer by coating the core obtained as described above using the material used for the coating layer as a coating material.

The present invention is a two-component developer containing the magnetic fine particle dispersed resin carrier and a toner. Next, the toner used for the two-component developer of the present invention will be described.
The toner used in the two-component developer of the present invention contains at least a binder resin, a colorant, and a release agent, and has a weight average particle diameter of 3.0 to 9.0 μm. An external additive may be added to the toner in the present invention as necessary.

When the weight average particle diameter of the toner exceeds 9.0 μm, the toner particles for developing the electrostatic charge image become large. Therefore, development faithful to the electrostatic charge image is difficult to be performed, and electrostatic transfer is performed. The toner tends to scatter. Further, when the weight average particle diameter of the toner is less than 3.0 μm, the handling property as the toner is lowered.

  As the binder resin used for the toner, known resins can be used, and among them, a polyester resin having a “polyester unit” is more preferable in terms of chargeability and fixability.

  The “polyester unit” used in the present invention means a portion derived from polyester. Specific examples of the polyester monomer constituting the polyester unit include divalent or higher alcohol monomer components and divalent or higher carboxylic acids, divalent or higher carboxylic acid anhydrides, and divalent or higher carboxylic acid esters. It means the monomer component.

In the toner of the present invention, it is preferable to use a resin having a polycondensation portion using a polyester monomer constituting these polyester units as a part of the raw material.
Such a binder resin includes (a) a polyester resin, (b) a hybrid resin having a polyester unit and a vinyl polymer unit, (c) a mixture of the hybrid resin and the vinyl polymer, (d) It is a resin selected from a mixture of a polyester resin and a vinyl polymer, (e) a mixture of a hybrid resin and a polyester resin, and (f) a mixture of a polyester resin, a hybrid resin, and a vinyl polymer.

In the binder resin contained in the toner in the present invention, “hybrid resin” means a resin in which a vinyl polymer unit and a polyester unit are chemically bonded. Specifically, it is a resin formed by a transesterification reaction between a polyester unit and a vinyl polymer unit obtained by polymerizing a monomer having a carboxylic acid ester group such as (meth) acrylic acid ester, preferably a vinyl polymer. A graft copolymer (or block copolymer) having a trunk polymer and a polyester unit as a branch polymer.
In the present invention, the “vinyl polymer unit” refers to a portion derived from a vinyl polymer. Examples of the vinyl monomer constituting the vinyl polymer unit include a monomer having a vinyl group used in the vinyl polymer.

  Specific examples of the dihydric or higher alcohol monomer component that is a monomer of the polyester unit include the following. As the dihydric alcohol monomer component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) Propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4- Alkylene oxide adducts of bisphenol A such as hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopenty Glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, hydrogen Additive bisphenol A etc. are mentioned.

  Examples of the trivalent or higher alcohol monomer component include sorbit, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol. 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Is mentioned.

  Examples of the divalent carboxylic acid monomer component include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; And succinic acid substituted with an alkyl group or alkenyl group having 6 to 18 carbon atoms or an anhydride thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, and citraconic acid, or anhydrides thereof.

Examples of the trivalent or higher carboxylic acid monomer component include trimellitic acid, pyromellitic acid, polyvalent carboxylic acid such as benzophenone tetracarboxylic acid and its anhydride, and the like.
Examples of other monomers include polyhydric alcohols such as oxyalkylene ethers of novolak type phenol resins.

  Among them, in particular, a bisphenol derivative represented by the following general formula (7) is used as a dihydric alcohol monomer component, and a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof, or a lower alkyl ester thereof ( For example, polyester resins obtained by condensation polymerization using fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) as acid monomer components are preferable because they have good charging characteristics.

(In the formula, R represents an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)

The binder resin contained in the toner in the present invention is preferably a resin having at least a polyester unit. More preferably, the polyester unit contained in the total binder resin is 30% by mass with respect to the total binder resin. % Of resin. More preferably, it is 40 mass% or more, Most preferably, it is 50 mass% or more.
When the polyester unit contained in the total binder resin is 30% by mass or more with respect to the total binder resin, it is preferable in that the fixing property and the charging stability are improved.

The following are mentioned as a vinyl-type monomer for producing | generating the vinyl-type polymer unit or vinyl-type polymer used for hybrid resin. Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert- Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-chloro styrene, 3, Styrene derivatives such as 4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, p-nitrostyrene; unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene and isoprene; Halogenation of vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, etc. Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate Α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, propyl acrylate, N-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, acrylate Acrylic acid esters such as vinyl; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole and N-vinyl carbazole N-vinyl compounds such as N-vinylindole and N-vinylpyrrolidone; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

  Unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid and mesaconic acid; unsaturated such as maleic acid anhydride, citraconic acid anhydride, itaconic acid anhydride and alkenyl succinic acid anhydride Dibasic acid anhydride: maleic acid methyl half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, alkenyl succinic acid Half esters of unsaturated dibasic acids such as acid methyl half ester, fumaric acid methyl half ester, and mesaconic acid methyl half ester; Unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid; Acrylic acid, Methacrylic acid, Croto Α, β-unsaturated acids such as acids and cinnamic acid; α, β-unsaturated acid anhydrides such as crotonic acid anhydride and cinnamic acid anhydride, anhydrides of the α, β-unsaturated acid and lower fatty acids Monomers having a carboxylic acid ester group such as alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, anhydrides thereof, and monoesters thereof are also exemplified as vinyl monomers.

  Acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1-methyl) (Hexyl) Styrene derivatives having a hydroxy group such as styrene may also be mentioned as vinyl monomers.

  In the present invention, the vinyl polymer and vinyl polymer unit of the binder resin may have a crosslinked structure crosslinked with a crosslinking agent having two or more vinyl groups. Examples of the crosslinking agent used in this case include divinylbenzene and divinylnaphthalene as aromatic divinyl compounds. Examples of diacrylate compounds linked by an alkyl chain include ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, and 1,6-hexane. Examples include diol diacrylate, neopentyl glycol diacrylate and the like, and those obtained by replacing acrylate of the above compound with methacrylate. Examples of diacrylate compounds linked by an alkyl chain containing an ether bond include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, The thing which replaced the acrylate of propylene glycol diacrylate etc. and the above compounds with methacrylate is mentioned. Examples of diacrylate compounds linked by a chain containing an aromatic group and an ether bond include polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2. , 2-bis (4-hydroxyphenyl) propane diacrylate and the like, and those obtained by replacing the acrylate of the above compound with methacrylate.

The vinyl polymer and the vinyl polymer unit may have a structure crosslinked with a polyfunctional crosslinking agent. Examples of the polyfunctional crosslinking agent used at that time include pentaerythritol triacrylate, trimethylolethane triacrylate, Trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, and those obtained by replacing the acrylate of the above compound with methacrylate; triallyl cyanurate, triallyl trimellitate, and the like.

  In the present invention, it is preferable to use a hybrid resin containing a monomer capable of reacting with components of both units in one or both of the vinyl polymer unit and the polyester unit. Among the polyester monomers constituting the polyester unit, those that can react with the components of the vinyl polymer unit include, for example, unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid, itaconic acid, and anhydrides thereof. Can be mentioned. Among the vinyl monomers constituting the vinyl polymer unit, those capable of reacting with the components of the polyester unit include vinyl monomers having a carboxyl group or a hydroxy group, and acrylic acid esters or methacrylic acid esters.

  As a method of obtaining a hybrid resin having a vinyl polymer unit and a polyester unit, there is a polymer containing a monomer component capable of reacting with each of the vinyl polymer unit and the polyester unit listed above. A method obtained by conducting a polymerization reaction of one or both resins is preferred.

  Examples of the polymerization initiator used in producing the vinyl polymer and the vinyl polymer unit used in the present invention include 2,2′-azobisisobutyronitrile, 2,2′-azobis (4 -Methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (-2,4-dimethylvaleronitrile), 2,2'-azobis (-2methylbutyronitrile), dimethyl-2,2 ' -Azobisisobutyrate, 1,1'-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyronitrile, 2,2'-azobis (2,4,4-trimethylpentane), 2 -Phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2,2'-azobis (2-methyl-propane), methyl ethyl ketone peroxide, a Ketone peroxides such as tylacetone peroxide and cyclohexanone peroxide, 2,2-bis (t-butylperoxy) butane, t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetra Methylbutyl hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, di-cumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide Oxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-trioyl peroxide, di-isopropyl peroxydicarbonate, di-2-ethyl Hexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxycarbonate, di-methoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxycarbonate, Acetylcyclohexylsulfonyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxylaur Rate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, di-t-butyl peroxyisophthalate, t-butyl peroxyallyl carbonate, t-amyl peroxy 2-ethylhexanoe DOO, di -t- butyl peroxy hexahydro terephthalate, di -t- butyl peroxy azelate, and the like.

Examples of the production method for preparing the hybrid resin used in the toner of the present invention include the following production methods (i) to (vi).
(I) A method in which a vinyl polymer, a polyester resin, and a hybrid resin are blended after production, and the blended product is obtained by dissolving and swelling the resin in an organic solvent (for example, xylene), and then distilling off the organic solvent. Manufactured by. The hybrid resin is synthesized by separately producing a vinyl polymer and a polyester resin, then dissolving and swelling them in a small amount of an organic solvent, adding an esterification catalyst and an alcohol, and heating to perform a transesterification reaction. The ester compound used can be used.
(Ii) A method of producing a polyester unit and a hybrid resin in the presence of a vinyl polymer after the production thereof. The hybrid resin comprises a reaction between a vinyl polymer unit (adding a vinyl monomer if necessary) and either a polyester monomer (polyhydric alcohol, polycarboxylic acid) or a polyester unit, or both. Produced by reaction. An organic solvent can be appropriately used.

(Iii) A method of producing a vinyl polymer unit and a hybrid resin in the presence of the polyester resin after the production. The hybrid resin is produced by a reaction between a polyester unit (added with a polyester monomer if necessary) and one or both of a vinyl polymer unit and a vinyl monomer. An organic solvent can be appropriately used.

(Iv) After the production of the vinyl polymer unit and the polyester unit, by adding one or both of a vinyl monomer and a polyester monomer (polyhydric alcohol, polycarboxylic acid) in the presence of these polymer units. A hybrid resin is produced. An organic solvent can be appropriately used.
(V) After producing a hybrid resin having a polyester unit and a vinyl polymer unit, a vinyl monomer and / or a polyester monomer (alcohol, carboxylic acid) is added to perform addition polymerization and / or condensation polymerization reaction. Vinyl polymers and / or polyester resins or even hybrid resins are produced. In this case, the hybrid component having the polyester unit and the vinyl polymer unit can be produced by the production methods (ii) to (iv) described above, and if necessary, produced by a known production method. It is also possible to use what has been made. Furthermore, an organic solvent can be used as appropriate.
(Vi) A vinyl polymer unit, a polyester unit, and a hybrid resin are produced by mixing vinyl monomers and polyester monomers (polyhydric alcohol, polycarboxylic acid) and continuously performing addition polymerization and condensation polymerization reactions. Is done. An organic solvent can be appropriately used.

In the production methods (i) to (vi), a plurality of polymer units having different molecular weights and different degrees of crosslinking can be used for the vinyl polymer unit and the polyester unit. In the present invention, the vinyl polymer means a vinyl monopolymer or a vinyl copolymer, and the vinyl polymer unit means a vinyl monopolymer unit or a vinyl copolymer unit. To do.

  The resin having a polyester unit that is preferably used as a binder resin for toner in the present invention has a main peak in a molecular weight range of 3,500 to 15,000 in a molecular weight distribution measured by gel permeation chromatography (GPC). It is preferable to have in a region having a molecular weight of 4,000 to 13,000. Moreover, it is preferable that Mw / Mn is 3.0 or more, and it is more preferable that it is 5.0 or more. When the main peak is in a region having a molecular weight of less than 3,500, the high temperature offset resistance of the toner tends to decrease. On the other hand, when the main peak is in the region where the molecular weight exceeds 15,000, the low-temperature fixability of the toner and the transparency of OHP tend to decrease. Further, when Mw / Mn is less than 3.0, good offset resistance tends to decrease.

The resin having a polyester unit that is preferably used as a binder resin for the toner of the present invention has a glass transition temperature (Tg) of 40 to 90 ° C. and a softening temperature (Tm) of 80 to 150 ° C. This is preferable for achieving both low-temperature fixability, high-temperature offset resistance, and dispersibility of the colorant.
In addition, the resin having a polyester unit that is preferably used as the toner binder resin in the present invention preferably has an acid value of less than 50 mgKOH / g from the viewpoint of improving the development durability stability and the dispersibility of the colorant.

  The toner used in the present invention can remarkably improve the fixability, and therefore it is preferable that the toner particles contain a wax as a release agent.

  The following are mentioned as an example of the wax used for this invention. Aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymers, microcrystalline wax, paraffin wax, Fischer-Tropsch wax; oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax or blocks thereof Copolymers: Waxes based on fatty acid esters such as ester waxes such as behenyl behenate and stearyl stearate, carnauba wax and montanic acid ester waxes; part or all of fatty acid esters such as deoxidized carnauba wax Examples include deoxidized ones. Furthermore, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, and seryl alcohol Saturated alcohols such as melyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis laurin Saturated fatty acid bisamides such as acid amide and hexamethylene bis stearic acid amide; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N ′ dioleyl adipic acid amide, N, N ′ dioleyl seba Unsaturated fatty acid amides such as acid amides; Aromatic bisamides such as m-xylene bis-stearic acid amide and N, N ′ distearyl isophthalic acid amide; Calcium stearate, calcium laurate, zinc stearate, magnesium stearate, etc. Aliphatic metal salts (generally referred to as metal soaps); waxes grafted with aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid; fatty acids such as behenic acid monoglycerides and many others Examples include partially esterified products of monohydric alcohols; methyl ester compounds having a hydroxyl group obtained by hydrogenation of vegetable oils and the like.

  Examples of the wax particularly preferably used in the present invention include aliphatic hydrocarbon waxes and esterified products which are esters of fatty acids and alcohols. For example, low molecular weight alkylene polymer obtained by radical polymerization of alkylene under high pressure or Ziegler catalyst or metallocene catalyst under low pressure; alkylene polymer obtained by thermal decomposition of high molecular weight alkylene polymer; synthesis containing carbon monoxide and hydrogen Synthetic hydrocarbon waxes obtained from the distillation residue of hydrocarbons obtained by gas from the gas or by hydrogenation of these are preferred. Further, those obtained by fractionating hydrocarbon wax by press sweating, solvent method, vacuum distillation or fractional crystallization are more preferably used. Hydrocarbon as a base is synthesized by the reaction of carbon monoxide and hydrogen using a metal oxide catalyst (mostly two or more multi-component systems) (for example, the Jintole method, Hydrocol method (a fluid catalyst bed Hydrocarbon compounds synthesized by use); hydrocarbons with up to several hundred carbon atoms obtained by the age method (using the identified catalyst bed) in which a large amount of wax-like hydrocarbons are obtained; alkylene such as ethylene by Ziegler catalyst Polymerized hydrocarbons are preferred because they are linear hydrocarbons with little branching, small and long saturation. In particular, a wax synthesized by a method that does not depend on polymerization of alkylene is preferable also from its molecular weight distribution. Paraffin wax is also preferably used.

  The wax used in the present invention preferably has a peak temperature of the maximum endothermic peak in the range of 60 to 130 ° C. in the endothermic curve in the differential thermal analysis (DSC) measurement. More preferably, it is the range of 65-125 degreeC, Most preferably, it is the range of 65-110 degreeC.

  When the maximum endothermic peak temperature of the wax is in the range of 60 to 130 ° C., the wax is suitably finely dispersed in the toner particles, which is preferable for exhibiting the effects of the present invention. On the other hand, when the maximum endothermic peak is less than 60 ° C., the blocking resistance of the toner deteriorates. Conversely, when the maximum endothermic peak exceeds 130 ° C., the fixability tends to deteriorate.

  As the colorant used in the toner in the present invention, known dyes and / or pigments are used. Although the pigment alone may be used, it is more preferable from the viewpoint of the image quality of the full-color image that the combination of the dye and the pigment improves the sharpness.

  Examples of the coloring pigment for magenta toner include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perlin compounds. Specifically, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 57: 1, 58, 60, 63, 64, 68, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 254, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned.

  Examples of the magenta toner dye include C.I. I solvent red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disper 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, and 28 are listed.

  Examples of the color pigment for cyan toner include C.I. I. Pigment Blue 1, 2, 3, 7, 15: 2, 15: 3, 15: 4, 16, 17, 60, 62, 66; I. Bat Blue 6, C.I. I. Acid Blue 45 or a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on a phthalocyanine skeleton having a structure represented by the following general formula (8).

（式中、ｎは１〜５の整数を示す。）

(In the formula, n represents an integer of 1 to 5.)

  Examples of the color pigment for yellow include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal compounds, methine compounds, and allylamide compounds. Specifically, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 155, 168, 174, 180, 181, 185, 191, C.I. I. Butt yellow 1, 3, 20, etc. 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.

As the black colorant used in the present invention, carbon black, iron oxide particles, and those which are toned in black using the colorant for yellow / magenta / cyan shown above can be used.
When the toner is produced in the present invention, it is preferable to use a toner obtained by mixing a colorant with a binder resin in advance and forming a master batch. Accordingly, the colorant can be favorably dispersed in the toner by melt-kneading the colorant master batch and other raw materials (binder resin, wax, etc.).

  In toner production, a toner obtained by masterbatching a colorant using a binder resin does not deteriorate the dispersibility of the colorant even when a large amount of colorant is used. Dispersibility is improved and color reproducibility such as color mixing and transparency is excellent. Further, a toner having a large covering power on the transfer material can be obtained. Further, by improving the dispersibility of the colorant, it is possible to obtain an image with excellent durability stability of toner chargeability and maintaining high image quality.

  The amount of the colorant used in the toner is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 12 parts by mass, and most preferably 2 to 10 parts by mass with respect to 100 parts by mass of the binder resin. . This is preferable in terms of color reproducibility and developability.

In the toner of the present invention, a known charge control agent can be used to stabilize the chargeability. The charge control agent varies depending on the type of charge control agent and the physical properties of other toner particle constituent materials, but generally 0.1 to 10 parts by mass per 100 parts by mass of the binder resin is preferably contained in the toner particles. More preferably, 0.1 to 5 parts by mass are contained. As such a charge control agent, there are known one that controls the toner to be negatively charged and one that controls the toner to be positively charged. One or two kinds of various kinds of charge control agents are used depending on the kind and use of the toner. The above can be used.

Negatively chargeable charge control agents include salicylic acid metal compounds, naphthoic acid metal compounds, dicarboxylic acid metal compounds, polymer compounds having sulfonic acid or carboxylic acid in the side chain, boron compounds, urea compounds, silicon compounds, calixarene Etc. are available. As the positively chargeable charge control agent, a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, an imidazole compound, or the like can be used. The charge control agent may be added internally or externally to the toner particles.
Since the two-component developer of the present invention is used for color image formation, the charge control agent is preferably an aromatic carboxylic acid metal compound that is colorless, has a high toner charging speed, and can stably maintain a constant charge amount. .

The toner in the present invention can be used after improving the fluidity of the toner by pulverizing and classifying and adding a fluidizing agent to the toner particles with a mixer such as a Henschel mixer.
As the fluidizing agent to be added to the toner particles, any fluidizing agent can be used as long as the fluidity can be increased by adding the toner particles before and after the addition. For example, fluororesin fine powder such as vinylidene fluoride fine powder, polytetrafluoroethylene fine powder, titanium oxide fine powder, alumina fine powder, wet production silica, silica fine powder such as dry production silica, silane compound, and There are treated silica fine powder and the like which have been subjected to a hydrophobic surface treatment with an organosilicon compound, a titanium coupling agent, silicone oil, and the like.

  Examples of the dry process silica include fine powders (so-called dry process silica or fumed silica) produced by vapor phase oxidation of a silicon halide compound by a conventionally known technique. Specifically, it utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.

SiCl ₂ + 2H ₂ + O ₂ → SiO ₂ + 4HCl

  In the above production method, for example, it is possible to obtain a composite fine powder of silica and another metal oxide by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halogen compound, and these are also included. The average particle size of the silica fine powder is desirably within the range of 0.001 to 2 μm, and particularly preferably, the silica fine powder within the range of 0.002 to 0.2 μm is used. Is good.

  Titanium oxide fine powders include sulfuric acid method in which titanium sulfate is hydrolyzed and calcined; chlorine method in which titanium tetrachloride is oxidized at high temperature, low temperature oxidation of volatile titanium compounds such as titanium alkoxide, titanium halide, titanium acetylacetonate ( Titanium oxide fine powder obtained by the method of thermal decomposition and hydrolysis) is used. As the crystal system, any of anatase type, rutile type, mixed crystal type thereof, and amorphous type can be used.

  As alumina fine powder, buyer method, improved buyer method, ethylene chlorohydrin method, underwater spark discharge method, organoaluminum hydrolysis method, aluminum alum pyrolysis method, ammonium aluminum carbonate pyrolysis method, aluminum chloride flame decomposition method The alumina fine powder obtained by the above is used. As the crystal system, α, β, γ, δ, ξ, η, θ, κ, χ, ρ type, mixed crystal type, amorphous type, α, δ, γ, θ type, these A mixed crystal type or amorphous type is preferably used.

As a method of hydrophobizing surface treatment, it is applied by chemical or physical treatment with an organosilicon compound that reacts or physically adsorbs with the fine powder used as the fluidizing agent.

  A preferable fluidizing agent is a silica fine powder produced by vapor phase oxidation of a silicon halide compound, which is treated with an organosilicon compound. Examples of organosilicon compounds include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, and bromomethyldimethyl. Chlorsilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyl Diethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3 -Diphenyltetramethyldisiloxane and dimethylpolysiloxane containing 2 to 12 siloxane units per molecule, each containing a hydroxyl group bonded to one Si at each terminal unit. These can be used alone or in a mixture of two or more.

  As the fluidizing agent used in the present invention, it is preferable to use a dry process silica that has been subjected to a hydrophobic surface treatment with a coupling agent having an amino group or silicone oil.

The fluidizing agent used in the present invention has good results when the specific surface area by nitrogen adsorption measured by the BET method is 30 m ² / g or more, preferably 50 m ² / g or more. The ratio of the fluidizing agent to the toner particles is preferably 0.01 to 8 parts by mass, more preferably 0.1 to 4 parts by mass with respect to 100 parts by mass of the toner particles.

  A procedure for manufacturing the toner will be described. The toner of the present invention is obtained by melt-kneading a binder resin, a colorant, a wax, and an arbitrary material, cooling and pulverizing the toner particles, and subjecting the toner particles to spheroidization and classification as necessary. It can be produced by mixing the fluidizing agent with toner particles as required.

  First, in the raw material mixing step, as a toner internal additive, at least a binder resin and a colorant are weighed and mixed in a predetermined amount and mixed. Examples of the mixing apparatus include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer.

  Further, the toner raw materials blended and mixed as described above are melt-kneaded to melt the resins and disperse the colorant and the like therein. In the melt-kneading step, for example, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. In recent years, single-screw or twin-screw extruders have become mainstream due to the advantage of being capable of continuous production. For example, KTK type twin-screw extruder manufactured by Kobe Steel, Ltd., TEM manufactured by Toshiba Machine Co., Ltd. In general, a mold twin screw extruder, a twin screw extruder manufactured by Kay Sea Kay Co., and a co-kneader manufactured by Buss are used. Furthermore, the colored resin composition obtained by melt-kneading the toner raw material is rolled by a two-roll roll after melt-kneading, and then cooled through a cooling step of cooling by water cooling or the like.

  In general, the cooled colored resin composition obtained above is then pulverized to a desired particle size in a pulverization step. In the pulverization step, first, coarse pulverization is performed by a crusher, a hammer mill, a feather mill, or the like, and further, pulverization is performed by a kryptron system manufactured by Kawasaki Heavy Industries, Ltd., a super rotor manufactured by Nisshin Engineering Co., Ltd., or the like. After that, if necessary, classification is performed using a classifier such as a classifier such as an inertia classification elbow jet (manufactured by Nippon Steel Mining Co., Ltd.), a centrifugal classification turbo plex (manufactured by Hosokawa Micron Co., Ltd.), In the present invention, a classified product having a weight average particle size of 3.0 to 9.0 μm is preferably obtained.

  If necessary, surface modification and spheronization treatment may be performed using, for example, a hybridization system manufactured by Nara Machinery Co., Ltd. or a mechano-fusion system manufactured by Hosokawa Micron Corporation. In such a case, if necessary, a sieving machine such as a wind-type sieve high voltor (manufactured by Shin Tokyo Machine Co., Ltd.) may be used. Furthermore, as a method of externally adding the external additive, a high-speed stirrer that mixes a predetermined amount of classified toner particles and various known external additives and gives shearing force to the powder such as a Henschel mixer or a super mixer is used. A method of stirring and mixing is used as an external additive.

In addition, as another method for producing a toner usable in the present invention, a method of directly producing toner particles using a suspension polymerization method, or an aqueous system that is soluble in a monomer and insoluble in a polymer obtained. Manufacture toner particles using a dispersion polymerization method that directly produces toner particles using an organic solvent, or an emulsion polymerization method typified by a soap-free polymerization method that produces toner particles by direct polymerization in the presence of a water-soluble polar polymerization initiator. You may use the method to do. In addition, a production method such as an interfacial polymerization method such as a microcapsule production method, an in situ polymerization method, or a coacervation method can also be used.

  In the case of producing toner particles using the suspension polymerization method, as a polymerization initiator, 2,2′-azohis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1'-azobis (an azo polymerization initiator such as cyclohexane-1-carbonitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide, Peroxide polymerization initiators such as methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used.

  Although the addition amount of a polymerization initiator changes with the target degree of polymerization, generally 0.5-20 mass% is added and used with respect to a monomer. The kind of the polymerization initiator varies slightly depending on the polymerization method, but can be used alone or in combination with reference to the 10-hour half-life temperature. It is also possible to add and use a known crosslinking agent, chain transfer agent, polymerization inhibitor, etc. for controlling the degree of polymerization.

  When suspension polymerization is used as a toner production method, an inorganic oxide can be used as a dispersant. Inorganic oxides include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, sulfuric acid Examples include barium, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, starch and the like. These are used by being dispersed in an aqueous phase. These dispersants are preferably used in an amount of 0.2 to 10.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  As these dispersants, commercially available ones may be used as they are, but in order to obtain dispersed particles having a fine uniform particle size, an inorganic compound can be produced in a dispersion medium under high-speed stirring. For example, in the case of tricalcium phosphate, a preferred dispersant for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring. Moreover, you may use together 0.001-0.1 mass part surfactant for refinement | miniaturization of these dispersing agents. Specifically, commercially available nonionic, anionic or cationic surfactants can be used, such as sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pendadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate. Calcium oleate is preferably used.

  When the direct polymerization method is used as the toner production method, the toner can be specifically produced by the production method described below. Monomer composition in which a release agent, a colorant, a charge control agent, a polymerization initiator, and other additives composed of a low softening substance are added to the monomer and dissolved or dispersed uniformly by a homogenizer, an ultrasonic disperser, etc. The product is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homomixer, homogenizer or the like. Preferably, the droplets made of the monomer composition are granulated by adjusting the stirring speed and time so as to have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving the durability, a part of the aqueous medium is retained after the latter half of the reaction or after the completion of the reaction in order to remove unreacted polymerizable monomers and byproducts. You may leave. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer composition.

As the shape of the toner used in the present invention, it is preferable that the average circularity of particles contained in the toner having an equivalent circle diameter of 2 μm or more of the toner is 0.920 or more and 0.970 or less.
When the average circularity of the toner is within this range, it is possible to remarkably improve transferability and cleaning properties while maintaining good chargeability and fixability of the toner.

  When the average circularity of the toner is less than 0.920, the variation in the contact area between the toner particles, between the toner and the carrier particles, and between the toner and the electrophotographic member such as the photosensitive drum or the intermediate transfer member increases. Due to the non-uniform charge distribution, toner separation from each member is worsened, and in particular, transfer defects may occur. Even when the fluidizing agent is added, it is difficult to uniformly add the toner particles to the surface of the toner particles, so that improvement in toner fluidity and transferability may hardly be obtained.

  When the average circularity of the toner exceeds 0.970, the shape of the toner approaches a perfect sphere, resulting in a cleaning failure such as the transfer residual toner slipping through the cleaning blade, surface modification, spheroidization, etc. By excessively carrying out the process, the wax in the toner particles tends to ooze out, and the developability may be deteriorated and the electrophotographic member may be contaminated.

  As described above, by using a two-component developer using the magnetic fine particle-dispersed resin carrier and toner, a two-component developer having further improved charging property, fixing property, transfer property, and cleaning property can be obtained. Obtainable.

  The above-mentioned magnetic fine particle-dispersed resin carrier having a magnetic fine particle-dispersed resin core having high electric resistance and saturation magnetization, and good remanence and fluidity, and the above-mentioned toner excellent in charging property, fixing property, transfer property and cleaning property Can be used in a two-component developer to further sharpen the charge distribution of the toner. In addition, the electrostatic latent image formed on the photosensitive member has a leakage of charge, unevenness in the stitches, edge effect, etc. As a result, it is possible to obtain a two-component developer in which the deterioration of the developer is suppressed without disturbing the latent image and further reducing the toner selective development, toner stress, and toner spent on the carrier. In addition, it has a synergistic effect that various characteristics of the toner can be maintained at a higher level, and an image having excellent dot reproducibility can be obtained at a high density over a long period of time even in different environments.

  When the two-component developer is prepared by mixing the magnetic fine particle dispersed resin carrier of the present invention and the toner, the mixing ratio is preferably 2 to 15% by mass, more preferably 4 to 4% as the toner concentration in the developer. When it is 13% by mass, good results are usually obtained. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if it exceeds 15% by mass, fogging or in-machine scattering tends to occur.

The physical property analysis / measurement method according to the present invention will be described below.
(1) The ratio A (mass%) of Fe ²⁺ to the total amount of Fe in the magnetic fine particle dispersed resin carrier, the ratios B and C (mass%) of Fe ²⁺ to the total amount of Fe in the magnetic fine particles, the total in the magnetic fine particles Ratio of metal elements other than Fe to Fe content (% by mass)
<Preparation of sample>
In the present invention, the magnetic fine particles and the non-magnetic fine particles used for the physical property measurement are separated from the magnetic fine particles and the non-magnetic fine particles before forming the core, or from the magnetic fine particle dispersed resin core. The powder is used as a sample. In either case, the physical property value does not change, but in order to avoid complication in this measurement method, a powder obtained by separating the core, magnetic fine particles, and nonmagnetic fine particles from the magnetic fine particle dispersed resin carrier is used. As a method for obtaining a powder comprising magnetic fine particles and non-magnetic fine particles, pretreatment is performed as follows.

  In order to separate the coating layer from the magnetic fine particle-dispersed resin carrier of the present invention, an organic solvent in which the coating layer is soluble (for example, methyl ethyl ketone, toluene, and a mixed solvent thereof) is used to perform peeling with an ultrasonic disperser, and a magnet Etc. to separate the coating layer and the core.

In order to separate the magnetic fine particles from the obtained core, the binder resin is swollen by immersing the core in an organic solvent having a high boiling point (for example, N-methylpyrrolidone) and heating to 180-190 ° C. in an oil bath. Then, the magnetic fine particles are desorbed with an ultrasonic disperser, and separated as a magnetic fine particle dispersion with a centrifugal separator or the like. The obtained dispersion is replaced and washed with an organic solvent such as methyl ethyl ketone, and the organic solvent is volatilized to obtain a powder composed of magnetic fine particles and nonmagnetic fine particles.
Using the obtained powder, the amount of Fe ²⁺ in the magnetic fine particle dispersed resin carrier is calculated as follows. Magnetic fine particles are separated from the powder using a magnet or the like. Using the obtained magnetic fine particles, the Fe ²⁺ ratio in the magnetic fine particles is calculated as follows.

<Ratio A (mass%) of Fe ²⁺ amount to total Fe amount in magnetic fine particle dispersed resin carrier>
25 g of a powder sample composed of magnetic fine particles and non-magnetic fine particles is added to 3800 ml of deionized water, and the mixture is stirred at a stirring speed of 3.5 s ⁻¹ while maintaining 35-40 ° C. in a water bath. 1250 ml of hydrochloric acid aqueous solution (deionized water) in which 424 ml of special grade hydrochloric acid reagent is dissolved is added to the slurry, and dissolution is started.
When the solution is completely dissolved from the start of dissolution, 100 ml is sampled and filtered through a 0.1 μm membrane filter, and the filtrate is collected. 25 ml of the collected filtrate is quantified with an ICP (plasma emission analysis). In quantification, a sample with a known iron element concentration is prepared and a calibration curve is prepared, and then the dissolved iron element concentration is quantified.

The ratio A of Fe ²⁺ amount in the magnetic fine particle dispersed resin carrier was adjusted by adding about 75 ml of deionized water to the remaining 25 ml of filtrate, adding sodium diphenylamine sulfonate as an indicator, and adding 0.1N weight. A redox titration using potassium chromate was performed, and the titration amount was determined with the sample colored blue-purple, and the ratio A (mass to the total Fe amount of Fe ^{2+ in} the magnetic fine particle dispersed resin carrier was calculated by the following formula. %).

<Fe ²⁺ ratio B and C (mass%) with respect to the total amount of Fe in the magnetic fine particles>
The ratio B (mass%) of Fe ^{2+ to} the total amount of Fe in 10% by mass from the particle surface and the ratio C (% by mass) of Fe ^{2+ to} the total amount of Fe in the remaining 90% by mass are determined as follows. It is done.

25 g of a powder sample obtained by separating only magnetic fine particles from magnetic fine particles and non-magnetic fine particles is added to 3800 ml of deionized water, and stirred at a stirring speed of 200 rpm while maintaining 35-40 ° C. in a water bath. 1250 ml of hydrochloric acid aqueous solution (deionized water) in which 424 ml of special grade hydrochloric acid reagent is dissolved is added to the slurry, and dissolution is started.
Sampling 50 ml every 10 minutes from the start of dissolution until it is completely dissolved and then filtered through a 0.1 μm membrane filter, and the filtrate is collected. 25 ml of the collected filtrate is quantified with an ICP (plasma emission analysis) to determine the iron element concentration, and the iron element dissolution rate is determined from the following formula. In quantification, a sample with a known iron element concentration is prepared and a calibration curve is prepared, and then the dissolved iron element concentration is quantified.

The Fe ²⁺ content in each sample was adjusted by adding about 75 ml of deionized water to 25 ml of the remaining filtrate, adding sodium diphenylamine sulfonate as an indicator, and adding 0.1 N potassium dichromate. Then, the redox titration is performed, and the titration amount is obtained with the point where the sample is colored blue-violet, and the ratio of Fe ^{2+ in} each sample is obtained.
The relationship between the iron element dissolution rate obtained here and the ratio of Fe ²⁺ is plotted, the ratio of Fe ²⁺ when the iron element dissolution rate reaches 10% by mass is B (% by mass), and the iron element dissolution rate is 10%. The proportion of Fe ²⁺ between mass% and 100 mass% is defined as C (mass%).

<Ratio (% by mass) of metal elements other than Fe with respect to the total amount of Fe in the magnetic fine particles>
Regarding the ratio (mass%) of the metal element other than Fe with respect to the total amount of Fe in the magnetic fine particles, the magnetic fine particles are dissolved by using the above method, and the obtained filtrate is obtained by using ICP (plasma emission analysis). The metal element concentration is quantified, and the ratio (mass%) of the metal element other than Fe to the total Fe amount in the magnetic fine particles is determined from the quantified value and the dissolved iron element concentration.

(2) Measurement of specific surface area BET of magnetic fine particles The specific surface area of magnetic fine particles is measured as follows. According to the BET method, nitrogen gas is adsorbed on the sample surface using a specific surface area measuring device Tristar3000 (manufactured by Shimadzu Corporation), and B
The specific surface area is calculated using the ET multipoint method. Before measuring the specific surface area, about 9 g of a sample is precisely weighed in a sample tube, and pretreated by evacuating at room temperature for 24 hours.

  Further, the magnetic fine particles are separated from the magnetic fine particle dispersed resin carrier in the same manner as in the measuring method (1).

(3) Measurement of resistivity of magnetic fine particle dispersed resin carrier, magnetic fine particle, and non-magnetic fine particle The resistivity of the magnetic carrier, magnetic fine particle, and non-magnetic fine particle is measured using the measuring apparatus shown in FIG. If necessary, pre-treatment is performed to prepare a sample (the magnetic fine particles and non-magnetic fine particles used in the magnetic fine particle-dispersed resin carrier are the same as the above-described pre-treatment for measuring the Fe ²⁺ content. Obtainable).

The resistivity is measured by filling the cell E with a sample, placing the lower electrode 11 and the upper electrode 12 in contact with the filled sample, applying a voltage between these electrodes, and measuring the current flowing at that time. By doing. The resistivity measurement conditions in the present invention are a contact area S between the filled sample and the electrode of about 2.4 cm ² , a sample thickness d of about 0.2 cm, and a load of the upper electrode of 240 g. The voltage is applied in the order of application conditions I, II, and III, and the current at the applied voltage under application condition III is measured. Thereafter, the thickness d of the sample is accurately measured, the resistivity (Ω · cm) at each electric field strength (V / cm) is obtained by calculation, and the resistivity at the electric field strength of 3000 V / cm is taken as the resistivity of the sample. .

Application condition I: (0V → 1000V: Increase in steps of 200V every 30 seconds)
II: (Hold for 30 seconds at 1000V)
III: (1000V → 0V: Decrease in steps of 200V every 30 seconds)

Resistivity of sample (Ω · cm) = (applied voltage (V) / measured current (A)) × S (cm ² ) / d (cm)
Electric field strength (V / cm) = applied voltage (V) / d (cm)

(4) Molecular weight distribution by GPC measurement of binder resin, toner, and binder resin for coating layer The molecular weight of the chromatogram by gel permeation chromatography (GPC) is measured under the following conditions. For the measurement, HLC-8120GPC (manufactured by Tosoh Corporation) is used. The column was stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) as a solvent was passed through the column at this temperature at a flow rate of 1 ml / min, and the sample concentration was adjusted to 0.05 to 0.6% by mass. About 50 to 200 μl of THF sample solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts (retention time). Examples of standard polystyrene samples for preparing a calibration curve include those manufactured by Tosoh Corporation or Pressure Chemical Co. The molecular weights manufactured are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8 .
It is appropriate to use 6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

As a column, in order to accurately measure a molecular weight region of 10 ^{3 to} 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, shodex GPC KF-801, 802 manufactured by Showa Denko KK , 803, 804, 805, 806, 807, or μ-styragel 500, 10 ³ , 10 ⁴ , 10 ⁵ manufactured by Waters.
Can be mentioned.

(5) Measurement of particle size of fine particles in coating layer The particle size of fine particles in the coating layer is measured as follows. Using a solvent in which the binder resin of the coating layer such as toluene is soluble from the magnetic fine particle dispersed resin carrier, a component dissolved in the solvent is obtained, and the particle size is 5 nm or more by a scanning electron microscope (50,000 times) Extract 500 or more random particles at random, measure the major axis and minor axis with a digitizer, average the particle size, and the particle size distribution of 500 or more particles (from the histogram of the column separated every 10 nm) The number average particle size is calculated with the particle size at the peak.

(6) Measurement of the particle size of carbon black (conductive fine particles) in the coating layer The particle size of the carbon black in the coating layer is measured as follows. Using a solvent in which the binder resin of the coating layer such as toluene is soluble from the magnetic fine particle dispersed resin carrier, a component dissolved in the solvent is obtained, and the particle size is 5 nm or more by a scanning electron microscope (50,000 times) Extract 500 or more carbon blacks at random, measure the major axis and minor axis with a digitizer, average the particle size, and the particle size distribution of 500 or more particles (from the histogram of the column divided every 10 nm) The number average particle size is calculated with the particle size at the peak of.

(7) Measurement of DBP oil absorption of carbon black in coating layer The DBP oil absorption of carbon is determined by the DBP oil absorption (dibutyl phthalate oil absorption) according to JIS-K 6221-1982 6.1.2 A method (mechanical kneading method). calculate.

(8) Measurement of magnetization strength of magnetic fine particle dispersed resin carrier and magnetic fine particle Dispersed resin carrier The strength of magnetization of magnetic fine particle dispersed resin carrier is the magnetic property of magnetic fine particle dispersed resin carrier and true specific gravity of magnetic fine particle dispersed resin carrier. It is demanded from. The magnetic properties of the magnetic fine particle-dispersed resin carrier were measured using a vibration magnetic field type magnetic property automatic recording device BHV-30 manufactured by Riken Denshi Co., Ltd. The measurement environment was 23 ° C. and 50% RH.
As a measurement method, a cylindrical plastic container is filled with a magnetic fine particle-dispersed resin carrier so as to be sufficiently dense, while an external magnetic field of 79.6 kA / m (1 kilo-Oersted) is created, and in this state the container The magnetization moment of the magnetic fine particle dispersed resin carrier filled in is measured. Further, the actual mass of the magnetic fine particle dispersed resin carrier filled in the container is measured to determine the strength of magnetization (Am ² / kg) of the magnetic fine particle dispersed resin carrier.

(9) Measurement of True Specific Gravity of Magnetic Fine Particle Dispersed Resin Carrier The true specific gravity of the magnetic fine particle dispersed resin carrier particles can be determined by, for example, a dry automatic density meter 1330 (manufactured by Shimadzu Corporation).
(10) Measurement of particle diameter of magnetic fine particle-dispersed resin carrier The average particle diameter of magnetic fine particle-dispersed resin carrier is 300 carrier particles having a particle diameter of 0.1 μm or more randomly with a scanning electron microscope (100 to 5000 times). Extracted as described above, the horizontal ferret diameter is measured as a carrier particle diameter by a digitizer, and the average value is calculated as the number average particle diameter of the magnetic fine particle dispersed resin carrier.

(11) Measurement of Toner Particle Size As a measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) is used. As the electrolytic solution, an about 1% NaCl aqueous solution is used. As the electrolytic solution, an electrolytic solution prepared using primary sodium chloride, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan Co., Ltd.) can be used.

  As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of the sample are measured for each channel by the measuring apparatus using a 100 μm aperture as the aperture. Volume distribution and number distribution are calculated. From these obtained distributions, the weight average particle diameter of the sample is determined. As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 00 μm; 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32-40.30 μm are used.

(12) Measurement of average circularity of toner The average circularity of toner is measured using a flow type particle image measuring apparatus “FPIA-2100 type” (manufactured by Sysmex Corporation), and is calculated using the following formula.

  Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define. The measurement uses the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm).

  In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are completely spherical. The more complicated the surface shape, the smaller the circularity. The average circularity C, which means the average value of the circularity frequency distribution, is calculated from the following equation, where ci is the circularity (center value) at the dividing point i of the particle size distribution and m is the number of measured particles.

  In addition, “FPIA-2100”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity. 1.0 is divided into classes equally divided every 0.01, and the average circularity is calculated using the center value of the division points and the number of measured particles.

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora150 type” (manufactured by Nikka Ki Bios Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more. In order to suppress variation in circularity, the installation environment of the apparatus is controlled at 23 ° C. ± 0.5 ° C. so that the in-machine temperature of the flow type particle image analyzer FPIA-2100 is 26 to 27 ° C. Preferably, autofocus is performed using 2 μm latex particles every 2 hours.

  To measure the circularity of the toner particles, the flow type particle image measuring device is used, and the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 particles / μl. Measure more than one. After the measurement, using this data, data having an equivalent circle diameter of less than 2 μm is cut to determine the average circularity of the toner particles.

  The measuring device used in the present invention, “FPIA-2100”, has a thinner sheath flow (7 μm →) than “FPIA-1000” that has been used to calculate the shape of the toner. 4μm) and improved processing particle image magnification, and further improved processing resolution of the captured image (256 × 256 → 512 × 512), the accuracy of toner shape measurement has been improved, thereby more reliably capturing fine particles It is a device that has achieved. Therefore, when it is necessary to measure the shape more accurately as in the present invention, the FPIA 2100 that can obtain information on the shape more accurately is more useful.

  Hereinafter, the present invention will be described in more detail with reference to specific production examples and examples, but the present invention is not limited thereto.

[Manufacture of magnetic fine particles]
<Manufacturing Example 1 of Magnetite Fine Particle 1: (M-1)>
2 liters of 0.1 mol calcium sulfate aqueous solution and 3 liters of 0.2 mol zinc sulfate aqueous solution were added to 50 liters of 2 mol / l ferrous sulfate aqueous solution, and 45 liters of 5 mol / l sodium hydroxide aqueous solution were mixed. A ferrous hydroxide slurry is obtained. The ferrous hydroxide slurry was maintained at pH 7.5 and a temperature of 90 ° C., and mechanical oxidation was performed to blow and oxidize the air. The obtained slurry containing magnetite fine particles was subjected to conventional filtration, washing, drying and pulverization to obtain magnetite fine particles (M-1). Table 1 shows the physical properties of the obtained magnetite fine particles (M-1).

<Magnetite fine particle production examples 2 to 9: (M-2) to (M-9)>
In Production Example 1 of magnetite fine particles, a ferrous hydroxide slurry was obtained by appropriately changing the amount of magnesium sulfate aqueous solution, calcium sulfate aqueous solution, titanyl sulfate aqueous solution, and zinc sulfate aqueous solution added to the ferrous sulfate aqueous solution. Magnetite particles (M-2) to (M-9) were obtained in the same manner except that the amount, reaction temperature, and reaction time were changed. Table 1 shows the physical properties of the obtained magnetite fine particles (M-2) to (M-9).

<Manufacturing Examples 10-13 of Magnetite Fine Particles: (M-10) to (M-13)>
Magnetite fine particles (M-10) to (M-) were similarly prepared except that the sulfate containing the Ca component and the Zn component in Magnetite Fine Particle Production Example 1 was not added, but the air inflow amount, reaction temperature, and reaction time were changed. 13) was obtained. Table 1 shows the physical properties of the obtained magnetite fine particles (M-10) to (M-13).

[Manufacture of coating materials used for coating layers]
<Manufacture example 1 of a coating material>
3 parts by mass of a methyl methacrylate macromer having an ethylenically unsaturated group at one end and a weight average molecular weight of 5,000, 46 parts by mass of a monomer having a unit represented by the following formula (9), and 51 parts by mass of methyl methacrylate were refluxed and cooled. Added to a four-necked flask equipped with a vessel, a thermometer, a nitrogen suction tube and a mixing type stirring device, and further 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, 2.4 parts by mass of azobisisovaleronitrile, and a nitrogen stream The temperature was kept at 80 ° C. for 10 hours to obtain a graft copolymer solution (solid content: 35% by mass). The weight average molecular weight according to gel permeation chromatogram (GPC) of the graft copolymer was 20,000.

  Melting resin fine particles (number average particle size 0.25 μm) 0.7 parts by mass, carbon black (number average particle size 35 nm, DBP oil absorption 50 ml / 100 g) 1 with respect to 30 parts by mass of the obtained graft copolymer solution The coating material α was obtained by stirring 2 parts by mass and 100 parts by mass of toluene with a homogenizer.

<Manufacture example 2 of a coating material>
A coating material β was produced in the same manner as in Coating Material Production Example 1 except that the amount of carbon black added in Coating Material Production Example 1 was changed to 24 parts by mass.

<Manufacture example 3 of a coating material>
In Production Example 1 of the coating material, the same procedure as in Production Example 1 of the coating material was carried out except that the monomer having the unit represented by the above formula (9) was changed to 4 parts by mass and 93 parts of methyl methacrylate macromer and melamine resin and carbon black were not added. Thus, a coating material γ was produced.

[Production of magnetic fine particle dispersed resin carrier]
<Production Example 1 of Magnetic Fine Particle Dispersed Resin Carrier>
First, a magnetic fine particle dispersed resin core was obtained as follows using the following materials.
-Phenol 10 parts by mass-Formaldehyde solution (37% by mass aqueous solution) 6 parts by mass-Magnetite fine particles (M-1) 84 parts by mass The above materials, 5% by mass of 28% by mass ammonia water, and 10 parts by mass of water are placed in a flask. While stirring and mixing, the temperature was raised to 85 ° C. in 30 minutes, and the polymerization reaction was carried out for 3 hours to cure. Then, after cooling to 30 degreeC and adding water, the supernatant liquid was removed, the precipitate was washed with water, and then air-dried. Subsequently, this was dried under reduced pressure (5 hPa or less) at a temperature of 60 ° C. to obtain a magnetic fine particle-dispersed resin core in which magnetic fine particles were dispersed.

Next, while stirring 1000 parts by mass of the obtained core while continuously applying shear stress, the coating material α30 parts by mass is gradually added, and the solvent is volatilized at 70 ° C. to coat the core surface. A coating layer was formed. The resin-coated magnetic fine particle dispersed resin carrier was heat-treated at 100 ° C. with stirring for 2 hours, classified by a sieve having an aperture of 76 μm, a number average particle size of 32 μm, a total Fe ²⁺ amount of 19.6% by mass, resistance Magnetic fine particle dispersed resin carrier (C-1) having a rate of 2.8 × 10 ⁹ Ω · cm, a true specific gravity of 3.6 g / cm ³ , a magnetization intensity of 64.8 Am ² / kg, and a residual magnetization of 5.88 Am ² / kg. ) Table 2 shows the physical properties of the obtained magnetic fine particle dispersed resin carrier (C-1).

<Production Examples 2 to 13 of magnetic fine particle dispersed resin carrier>
In Production Example 1 of the magnetic fine particle dispersed resin carrier, except that the magnetic fine particles were changed to (M-2) to (M-13), the amount of hematite used (see Table 2), and the type of the coating material were changed. Magnetic fine particle dispersed resin carriers (C-2) to (C-13) were obtained in the same manner as in Production Example 1 of magnetic fine particle dispersed resin carrier. Table 2 shows the physical properties of the obtained magnetic fine particle dispersed resin carriers (C-2) to (C-13).

[Manufacture of toner]
<Toner Production Example 1>
As a vinyl monomer of the vinyl polymer unit, 1.1 mol of styrene, 0.14 mol of 2-ethylhexyl acrylate, 0.1 mol of acrylic acid, and 0.05 mol of dicumyl peroxide are placed in a dropping funnel. Moreover, as a polyester-type monomer of a polyester unit, 2.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis ( 4-hydroxyphenyl) propane 0.8 mol, terephthalic acid 0.8 mol, trimellitic anhydride 0.6 mol, fumaric acid 1.5 mol, and dibutyltin oxide 0.2 g were placed in a glass 4-liter four-necked flask and the temperature A meter, a stirring bar, a condenser, and a nitrogen introduction tube were attached and placed in a mantle heater. Next, after the inside of the flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and while stirring at a temperature of 145 ° C., the vinyl monomer, the crosslinking agent and the polymerization initiator were added from the previous dropping funnel over 4 hours. And dripped. Subsequently, the temperature was raised to 245 ° C. and reacted for 4 hours to obtain a hybrid resin A having a polyester unit. As the hybrid resin A, a resin having a weight average molecular weight of 80000 and a number average molecular weight of 3200 was obtained.

-Hybrid resin A 100 parts by mass-Paraffin wax (maximum endothermic peak temperature 78 ° C) 5 parts by mass-3,5-di-t-butylsalicylic acid aluminum compound 0.7 parts by mass I. Pigment Blue 15: 3 4.8 parts by mass

  After mixing the ingredients of the above formulation with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), a twin-screw kneader (PCM-30 type, manufactured by Ikekai Tekko Co., Ltd.) set at a temperature of 130 ° C. ). The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely pulverized toner was pulverized using a collision-type airflow pulverizer using high-pressure gas. Furthermore, classification was performed by a multi-division classifier using the Coanda effect to obtain cyan toner particles. Surface modification was performed using a mechanofusion system equipped with a cooling mechanism such as a chiller unit to obtain cyan toner particles having a weight average particle diameter of 6.5 μm and an average circularity of 0.945.

  To 100 parts by mass of the obtained cyan toner particles, 1.0% by mass of titanium oxide fine powder having a primary average particle size of 55 nm and a surface treatment with isobutyltrimethoxysilane and 1.0% by mass of hydrophobic silica fine powder were added. Toner a was obtained by mixing with a mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.).

<Toner Production Examples 2-3>
In Toner Production Example 1, the toners b and c were prepared in the same manner as in Toner Production Example 1 except that cyan toner particles having an average circularity of 0.920 and 0.970 were obtained by changing the treatment time during surface modification. Obtained.

<Example 1>
To 92 parts by mass of the magnetic fine particle-dispersed resin carrier (C-1), 8 parts by mass of toner a was added and mixed by a tumbler mixer to obtain a two-component developer.
Using this developer, Canon Co., Ltd. full color copier CLC5000 remodeling machine (laser spot diameter can be reduced and output at 600 dpi, the surface of the fixing roller of the fixing unit is changed to a PFA tube, and the oil application mechanism is removed. N / N under normal temperature and normal humidity (23 ° C., 50% RH), N / L under normal temperature and low humidity (23 ° C., 5% RH), H / H under high temperature and high humidity (equipment applied to CLC5000) (30 ° C., 80% RH), a printing ratio of 10%, and continuous image output evaluation of 30000 sheets was performed. The developing condition is that the developing sleeve and the photosensitive member are rotated in the forward direction in the developing region, the developing sleeve is 1.8 times that of the photosensitive member, Vd: −600 V, Vl: −110 V, Vdc: −460 V, and Vpp2. .1 kV, frequency 1.9 kHz. The evaluation items and evaluation criteria for image output are shown below, and the evaluation results are shown in Table 3.

<Dot reproducibility>
A 30H image was formed using the toner and the modified machine, and this image was visually observed. The dot reproducibility of the image was evaluated based on the following criteria. The 30H image is a halftone image when 256 gradations are displayed in hexadecimal, 00H is solid white, and FFH is solid black. The evaluation criteria are as follows.
A: Smooth and smooth.
B: I don't feel a lot of rustling.
C: Although there is a slight feeling of roughness, it is at a level where there is no practical problem.
D: There is a feeling of roughness and is a problem.
E: There is a very rough feeling.

<Image density>
When the solid image was fixed at 180 ° C., the density of the fixed image was measured with a densitometer X-Rite500 type, and the average value of 6 points was taken as the image density.

<Carrier adhesion>
After Vdc is set to −400 V and the above solid white image is output, a transparent adhesive tape is closely adhered to the portion on the photoconductor between the developing unit and the cleaner unit, and is sampled on the photoconductor in 5 cm × 5 cm. The number of magnetic fine particle dispersed resin carriers adhering was counted, and the number of adhering carriers per 1 cm ² was calculated. The evaluation criteria are as follows.
A: 10 pieces / cm ² or less B: 11-20 pieces / cm ²
C: 21-50 cells / cm ² (practical level limit)
D: 51-100 pieces / cm ²
E: 101 pieces / cm ² or more

<Outline evaluation>
A chart in which halftone horizontal bands (30H width 10 mm) and solid black horizontal bands (FFH width 10 mm) are alternately arranged in the transfer paper conveyance direction is output. The image is read by a scanner and binarized. Taking the luminance distribution (256 gradations) of a certain line in the conveyance direction of the binarized image, drawing a tangent to the luminance of the halftone at that time, and deviating from the tangent at the rear end of the halftone part until it intersects with the solid part luminance The brightness area (area: sum of the brightness numbers) is used as the whiteness degree. The evaluation criteria are as follows.
A: 50 or less, hardly noticeable and very good.
B: 51 to 150, good.
C: 151-300, white spots are present, but at a level where there is no practical problem.
D: 301 to 600, white spots are conspicuous, which is a problem.
E: 601 or more, very noticeable.

<Toner spent>
The two-component developer used in the present invention is placed in a CLC5000 developer, and the developing sleeve is spun at a process speed of 800 mm / sec for 1 hour in each environment, and then the two-component developer is removed from the sleeve surface. The toner and the carrier were sampled, and the carrier after idling was observed with a scanning electron microscope (SEM), and a halftone image was output to evaluate the toner spent property. The evaluation criteria are as follows.
A: Toner hardly adheres to the carrier surface B: Toner slightly adheres to the carrier surface, but there is no problem in practical use C: Toner fusing occurs but no scumming occurs (lower limit of practical use) level)
D: Toner fusing occurs and some background staining is observed E: Toner fusing occurs and background staining is remarkable

<Examples 2 to 13 and Comparative Examples 1 to 4>
Images were evaluated and evaluated in the same manner as in Example 1 except that the magnetic fine particle-dispersed resin carrier and toner used in Example 1 were combined in the combinations shown in Table 3. The evaluation results are shown in Table 3.

It is the schematic of the apparatus used in order to measure the resistivity of the magnetic fine particle dispersion type | mold resin carrier of this invention, and a magnetic fine particle.

Explanation of symbols

11: Lower electrode 12: Upper electrode 13: Insulator 14: Ammeter 15: Voltmeter 16: Constant voltage device 17: Sample 18: Guide ring d: Sample thickness E: Resistance measurement cell

Claims (5)

In a magnetic carrier having a magnetic fine particle dispersed resin core containing at least magnetic fine particles and a binder resin, and a coating layer covering the surface of the magnetic fine particle dispersed resin core,
The resistivity of the magnetic fine particles Ri ^{1 × 10 6 ~1 × 10 10} Ω · cm der,
The magnetic fine particles contain Fe and at least one of Mg component, Ca component, Ti component and Zn component, and the total amount in terms of each element is 0.3 to 4.0% by mass with respect to the total Fe amount. A magnetic fine particle-dispersed resin carrier. The magnetic fine particle has a ratio of Fe ^{2+ to} the total Fe amount in 10% by mass from the surface, B (% by mass), and the ratio of Fe ^{2+ to} the total Fe amount in 90% by mass, C (% by mass). 2 satisfies the following formula (1): The magnetic fine particle dispersed resin carrier according to claim 1 .
0.3 ≦ B / C <1.0 (1) The ratio A (mass%) of Fe ²⁺ with respect to the total Fe amount in the magnetic fine particle dispersed resin carrier satisfies the following formula (2), and the resistivity is 1 × 10 ⁷ to 1 × 10 ¹¹ Ω · cm. The magnetic fine particle-dispersed resin carrier according to claim 1 or 2 .
5.0 ≦ A ≦ 30 (2) In a two-component developer containing a toner and a magnetic carrier,
The toner contains at least a binder resin, a colorant, and a release agent, and has a weight average particle size of 3.0 to 9.0 μm.
The two-component developer, wherein the magnetic carrier is the magnetic fine particle-dispersed resin carrier according to any one of claims 1 to 3 . 5. The binder resin according to claim 4 , wherein the binder resin includes at least a polyester unit, and an average circularity of particles in the toner having an equivalent circle diameter of 2 μm or more of the toner is 0.920 or more and 0.970 or less. Component developer.

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