JP2693084B2 - Electrophotographic carrier, two-component developer, electrophotographic carrier manufacturing method and image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic carrier having an electrophotographic carrier core having a carrier core in which a magnetic material is dispersed, and a method for producing the same. Further, the present invention is a two-component developer for developing an electrostatic image having a toner and a carrier, and an image formation for developing a latent image by applying a bias voltage in a developing region using the two-component developer. Regarding the method.

[0002]

2. Description of the Related Art Generally, in an electrostatic recording apparatus using electrophotography, selenium, OPC (organic photoconductor), α-S
After using a photoconductive substance such as i as the electrostatic charge image carrier and uniformly charging the electrostatic charge image carrier by various means,
The surface of the electrostatic charge image carrier is irradiated with an optical image to form an electrical latent image corresponding to the optical image on the surface of the electrostatic charge image carrier, and the latent image is subjected to a magnetic brush developing method or other developing method. A method in which toner is applied to make the image visible is generally adopted.

In this developing method, a toner for visualizing the latent image and carrier particles having a magnetic material called a carrier are used, and the carrier has an appropriate amount of positive or negative electricity due to triboelectric charging. Is applied to the toner, and the toner is carried on the surface by the electrostatic attraction of the triboelectric charging.

The developer containing the above toner and carrier is
A developing area formed between the electrostatic charge image bearing member and the developing sleeve by coating a developing layer containing a magnet with a predetermined layer thickness by a developer layer thickness regulating member and utilizing magnetic force. Be transported to.

A predetermined developing bias voltage is applied between the electrostatic image carrier and the developing sleeve, and the toner is developed on the electrostatic image carrier in the developing area.

Generally, the carriers constituting the two-component developer are roughly classified into conductive carriers and insulating carriers. Although there are various characteristics required for these carriers, particularly important characteristics include appropriate charging property, pressure resistance against applied electric field, impact resistance, abrasion resistance, spent resistance, developability, and productivity. .

[0007] Oxidized or unoxidized iron powder is usually used as the conductive carrier. However, the developer containing the iron powder carrier as the component has unstable triboelectric chargeability to the toner, and therefore, depending on the developer. There is a problem that fog occurs in the formed visible image. That is, with the use of the developer, the toner particles adhere to the surface of the iron powder carrier particles, so that the electric resistance of the carrier particles increases, the bias current decreases, and the triboelectrification becomes unstable. The image density of the visible image decreases and fog increases.

As the insulating carrier, a carrier in which the surface of carrier core material particles generally made of a ferromagnetic material such as iron, nickel and ferrite is uniformly coated with an insulating resin is typical. In a developer using this carrier, toner particles are less likely to fuse to the surface of the carrier than in the case of a conductive carrier, and have excellent durability and a long service life. It has the advantage of being suitable.

On the other hand, when the true specific gravity is increased irrespective of the conventional conductive or insulative carrier, when the developer is made to have a predetermined layer thickness on the sleeve by the developing layer thickness regulating member,
Since the load applied to the developer becomes large, (a) toner filming (b) carrier destruction (c) toner deterioration is likely to occur during long-term use of the developer, resulting in deterioration of the developer and As a result, the image quality of the developed image is likely to deteriorate. When the particle size of the carrier is large, the load on the developer is large, so that the above (a) to (c) are more likely to occur, and as a result, the deterioration of the developer is more likely to occur. Further, (d) the reproducibility of fine lines in the developed image is poor.

That is, it is well known that the developability is poor.

Therefore, in the carrier in which the above (a) to (c) are likely to occur, it is necessary to periodically replace the developer and it is uneconomical, so that the load on the developer is reduced. Alternatively, it is necessary to improve the impact resistance and spent resistance of the carrier to prevent the above (a) to (c) and extend the life of the developer.

Furthermore, it is necessary to deal with the problem of developability (d) by reducing the particle size of the carrier.

To solve the above problems (a) to (d), a carrier having a small particle size in which magnetic particles are dispersed in a binder resin, for example, a pulverizing method disclosed in JP-A-54-66134 is used. It is possible to deal with the magnetic substance dispersion type small particle size carrier, and it is also possible to deal with the magnetic substance dispersion type small particle size carrier by the polymerization method disclosed in JP-A-61-9659. .

However, the above-mentioned magnetic substance-dispersed small particle size carrier has a small saturation magnetization with respect to the particle size when a large amount of the magnetic substance is not contained in the carrier particles, and (e) the photoconductor during development. Since there is a problem that carrier adheres on the top, the developer must be replenished or the adhered carrier must be collected in the image forming apparatus, which is a drastic measure for extending the life of the developer. It has the drawback that it cannot be

When a large amount of the magnetic material is contained in the above-mentioned magnetic material-dispersed small particle size carrier, the amount of the magnetic material is increased with respect to the binder resin, so that the impact resistance becomes weak and the development is performed. When the developer is made to have a predetermined layer thickness on the sleeve by the developer layer thickness regulating member, the magnetic substance is likely to be missing from the carrier, and as a result, the developer is likely to be deteriorated. However, it has a drawback that it cannot be a drastic measure for extending the life of the developer.

Further, when a large amount of a magnetic material is contained in the magnetic material-dispersed small particle size carrier, the resistance of the carrier is lowered due to an increase in the amount of the magnetic material having a low resistance. f) It also has a drawback that image defects are likely to occur due to leakage of bias voltage applied during development.

Therefore, even in the above-mentioned magnetic substance-dispersed small particle size carrier having an increased amount of magnetic substance, there is a drawback that it cannot be drastically improved as a measure for improving the developing property and extending the life of the developer. ing.

It is also possible to deal with it by the technique of coating the carrier with a resin, which is disclosed in JP-A-58-21750. According to the carrier coated with the above resin, it is possible to improve the spent resistance, impact resistance, and pressure resistance against an applied voltage. Furthermore, since it is possible to control the charging characteristics of the toner by the charging characteristics of the resin to be coated, it is possible to impart a desired charging charge to the toner by selecting the resin to be coated.

However, also in the above resin-coated carrier, when the amount of the coating resin is large and the resistance of the carrier is high, the so-called toner charge-up phenomenon, in which the toner charge amount becomes large in a low humidity environment, easily occurs, When the amount of the coating resin is small, the resistance of the carrier becomes too low, which easily causes an image defect due to the leak of the developing bias voltage, which makes it difficult to control the coating amount.

Depending on the coating resin, even if the resistance of the carrier coated with the resin is considered to be an appropriate resistance for measurement, image defects are likely to occur due to leakage of the developing bias voltage. Considering it, there is a problem that its control is difficult.

In general, the charge amount of a developer using a carrier coated with such an insulating resin is likely to change with changes in environmental conditions such as low temperature and low humidity and high temperature and high humidity. as a result,
For example, under low temperature and low humidity, image density is reduced due to charge-up, and under high temperature and high humidity, problems such as fog and scattering due to reduction of tribo occur.

Therefore, it is the present situation that a carrier coated with an insulating resin having a satisfactory level has not yet been found.

Various attempts have been made for carriers which are not coated with an insulating resin.
Japanese Patent No. 229256 proposes a carrier in which a water-soluble quaternary ammonium salt is attached to the surface of ferrite particles. However, when a water-soluble quaternary ammonium salt is used, the quaternary ammonium salt on the surface of the ferrite particles is eluted or desorbed due to long-term storage under high temperature and high humidity or durability, and untreated ferrite particles are untreated. It had the drawback of gradually approaching the nature of. Furthermore, since it is not coated with a resin, the quaternary ammonium salt on the surface of the ferrite particles is easily desorbed not only in the high temperature and high humidity environment but also in the normal environment of normal temperature and normal humidity. Compared with the above, there is a problem that a film body is formed by the toner on the surface of the carrier, which is weak against so-called toner spent and the life of the developer is short. Furthermore, if not covered with an insulating resin to some extent, not only iron oxide powder but also ferrite particles, current leaks to the developing system where a bias voltage is applied, or carrier adheres to the photoreceptor. Inappropriate. As described above, with respect to the durability and toner spent resistance of the carrier, there is currently no method better than coating with an insulating resin.

As described above, considering the above-mentioned required characteristics of the carrier, the conventionally used carrier still has a problem to be improved, and a sufficiently satisfactory carrier is not known so far.

In particular, in a magnetic substance dispersion type carrier in which magnetic particles are dispersed in a binder resin and the surface of which is coated with a resin, (1) Spent resistance (2) Impact resistance (prevention of carrier destruction) ) (3) Prevention of toner deterioration (4) Developability (5) Prevention of carrier adhesion on photoconductor (6) Control of carrier resistance (7) Stabilization of toner chargeability (longer life of chargeability) (8) It is not known so far that the stabilization of the chargeability of the toner against environmental changes is sufficiently satisfied.

In particular, in recent years, there has been a tendency to reduce the toner particle size from the standpoint of high image quality, and therefore the variation in the toner charge amount due to changes in the temperature and humidity of the environment is likely to become even greater. There is a problem that it is more difficult to achieve both prevention of toner scattering and fogging due to a decrease in charge amount in a humid environment and prevention of low image density due to charge-up in a low humidity environment.

[0027]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of an electrophotographic carrier in which a magnetic material having a surface coated with a resin is dispersed. It is an object of the present invention to provide an electrophotographic carrier which is excellent in developability and developer life by stabilizing the chargeability of toner during running and humidity fluctuations without requiring carrier replenishment.

It is an object of the present invention to provide a carrier for electrophotography, which has an appropriate resistance and has little leakage of current even when a bias voltage is applied or the carrier is not attached to a photoreceptor. To do.

An object of the present invention is to provide an electrophotographic carrier capable of reducing the share of toner, suppressing toner deterioration, and stably providing high image quality over a long period of time.

An object of the present invention is to provide a method for manufacturing an electrophotographic carrier which can solve the above problems.

It is an object of the present invention to provide an image forming method in which, when a bias voltage is applied to a developing area to develop a latent image, current leakage or carrier adhesion to an electrostatic image carrier is reduced. To do.

It is an object of the present invention to provide a two-component developer for developing an electrostatic charge image having a small environmental change even when a toner having a small particle size having a weight average particle size of 10 μm or less is used.

[0033]

The present invention relates to an electrophotographic carrier having a carrier core material and a resin coating material for coating the surface of the carrier core material, wherein the carrier core material is a binder resin and The resin coating material has magnetic fine particles dispersed in a binder resin, and the resin coating material is (a) a vinyl-based copolymer having a hydroxyl value of 1 to 100 (KOHmg / g), and (b) 30 to 30. Styrene having a monomer ratio of acrylic component of 90% by weight, a weight average molecular weight (Mw) of 30,000 to 70,000 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10
The above object is achieved by containing at least one member selected from the group consisting of acrylic copolymers.

[0034]

The present invention provides a two-component developer having a toner, a carrier core material and a carrier having a resin coating material for coating the surface of the carrier core material, wherein the carrier core material is a binder resin and the binder resin. The resin coating material has magnetic fine particles dispersed in a resin, and the resin coating material comprises (a) 1 to 1
Vinyl copolymer having a hydroxyl value of 00 (KOHmg / g), and (b) monomer ratio of acrylic component of 30 to 90% by weight, weight average molecular weight (Mw) of 30,000 to 70,000 and weight average of 2 to 10 The above object is achieved by containing at least one member selected from the group consisting of styrene-acrylic copolymers having a molecular weight / number average molecular weight (Mw / Mn).

[0036]

The present invention prepares a coating solution or coating dispersion in which a resin coating material is dissolved or dispersed, coats the surface of a carrier core material with the prepared coating solution or coating dispersion, and forms a coated carrier. In the method of manufacturing an electrophotographic carrier for obtaining a carrier by drying a core material, the carrier core material has a binder resin and magnetic fine particles dispersed in the binder resin, and the resin coating material is , (A) 1 to 10
Vinyl-based copolymer having a hydroxyl value of 0 (KOHmg / g), and (b) a monomer ratio of an acrylic component of 30 to 90% by weight, a weight average molecular weight (Mw) of 30,000 to 70,000 and a weight average of 2 to 10. Molecular weight /
The above object is achieved by containing at least one member selected from the group consisting of styrene-acrylic copolymers having a number average molecular weight (Mw / Mn).

[0038]

The present invention relates to an image forming method for developing a latent image formed on an electrostatic charge image bearing member by applying a bias voltage in a developing area and using a two-component developer having a toner and a carrier. Is a vinyl-based copolymer having a binder resin and magnetic fine particles dispersed in the binder resin, and the resin coating material has (a) a hydroxyl value of 1 to 100 (KOHmg / g). , And (b) 3
0 to 90 wt% acrylic component monomer ratio, 30
Weight average molecular weight (Mw) of 000 to 70,000 and 2
To 10 weight average molecular weight / number average molecular weight (Mw / M
The above object is achieved by containing at least one member selected from the group consisting of styrene-acrylic copolymers having n).

[0040]

The carrier of the present invention improves the various drawbacks of the conventional resin-coated magnetic material dispersion type carrier, and is not dependent on impact resistance, electric resistance value, stability of charge imparting to toner for a long time, and environmental fluctuation. It is believed that the reason why the carrier of the present invention is remarkably excellent in developability and developer life is due to the following reasons, though it is excellent in stability of imparting charge to the toner.

When the surface of the carrier of the present invention was observed with a scanning electron microscope, it was observed that the carrier core material was uniformly coated with the coating resin. Therefore, it is considered that the uniform coating property improves the impact resistance, the resistance value, and the stability of charge imparting to the toner of the magnetic material-dispersed carrier used in the present invention.

That is, when the surface of the carrier is divided into minute parts and the coating is uniform,
It is considered that the impact resistance, the resistance value, and the charge imparting property to the toner exhibit the same characteristics in every part.

On the other hand, when the coating is nonuniform, it is considered that the impact resistance, the resistance value, and the charge imparting property to the toner are different in each part of the carrier surface. Therefore, for example, the measurement of the resistance value is an evaluation method when the carrier is viewed from a macro standpoint, so even if the resistance value is considered to be an appropriate resistance in the measurement, if the coating is non-uniform, low humidity It is considered that there is a problem that a charge-up phenomenon is likely to occur in an environment, or an image defect is likely to occur due to leakage of a developing bias voltage.

When the resin coating material for coating the surface of the carrier core material contains a vinyl type copolymer having a hydroxyl value of 1 to 100 (KOHmg / g),
Since this vinyl-based copolymer has excellent binding properties, the resin coating material is firmly fixed to the surface of the carrier core material. Further, this resin coating material preferably contains a fluorine-containing resin. The resin coating material for coating the surface of the carrier core material has a monomer ratio of an acrylic component of 30 to 90% by weight, a weight average molecular weight of 30,000 to 70,000, and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10. In the case of containing a styrene-acrylic copolymer having), the surface of the carrier core material can be uniformly coated with the resin coating material, and high strength against impact resistance can be obtained. Further, this resin coating material preferably contains a fluorine-containing resin.

Further, in the present invention, the resin coating material for coating the surface of the carrier core material is, in addition to the above-mentioned copolymer as an insulating resin, a quaternary ammonium represented by the following general formula (I). salt

[0047]

[Outside 14] (In the formula, R ₁ , R ₂ , R ₃ and R _{4, which} may be the same or different, each represents an alkyl group, an aryl group or an aralkyl group, and A represents an organic anion or a polyacid ion. .) Is contained, the mechanism is not clear, but the quaternary ammonium salt used in the present invention improves the environmental dependency of the resin coating material coated on the surface of the carrier core material. It is preferable because it can be performed. It is speculated that the reason why this effect is obtained is that the quaternary ammonium salt of the present invention serves as a leak site to prevent the phenomenon that the insulating and coating resin is charged up under low humidity.

The vinyl copolymer having a hydroxyl value used in the present invention is a copolymer of a vinyl monomer having a hydroxyl group and another vinyl monomer. As the vinyl monomer having a hydroxyl group, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxy-3-phenyloxypropyl acrylate,
2-hydroxyethyl methacrylate, 2-methacrylic acid 2-
There are hydroxypropyl, 2-hydroxybutyl methacrylate, 2-hydroxy-3-phenyloxypropyl methacrylate and the like. It is necessary to use these monomers so that the hydroxyl value of the copolymer is 1 to 100 (KOHmg / g), and preferably 5 to 70,
It is more preferable to use it so as to be 10 to 50 (KOHmg / g).

This hydroxyl value is 1 (KOHmg /
If it is less than g), the effect of having a hydroxyl group cannot be exhibited.

Further, when the resin coating material contains a fluorine-containing resin, the effect of exposing the fluorine-containing resin to the carrier surface is insufficient, and the charge imparting ability of the carrier is lowered.
When the hydroxyl value is more than 100 (KOHmg / g), the hygroscopicity is increased and the charge stability under high temperature and high humidity is lowered.

Other vinyl monomers copolymerized with these hydroxyl group-containing vinyl monomers include styrene, α-methylstyrene, p-methylstyrene and p-methylstyrene.
Styrene derivatives such as -t-butylstyrene and p-chlorostyrene; methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, nonyl methacrylate,
Decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, glycidyl methacrylate, methoxyethyl methacrylate, propoxyethyl methacrylate, butoxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate Butyl acrylate,
Mention may be made of pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, vinyl monomers.

Of these other vinyl monomers, the vinyl monomer having one vinyl group in one molecule is preferably styrene, a styrene derivative, a methacrylic acid ester or an acrylic acid ester, and particularly preferably 1 to 5 for the alkyl group. Alkyl esters of methacrylic acid or acrylic acid having 4 carbon atoms are preferred.

Among these vinyl monomers, the vinyl monomer having a hydroxyl group is used so that the hydroxyl value of the copolymer will be 1 to 100 (KOHmg / g). These vinyl monomers are copolymerized by methods such as suspension polymerization method, emulsion polymerization method and solution polymerization method.

These copolymers have a weight average molecular weight of 1
It is preferably from 10,000 to 70,000. If the weight average molecular weight is less than 10,000, the impact resistance tends to be insufficient, and if it exceeds 70,000, it becomes difficult to coat the carrier core material and aggregates are formed, which is not preferable. This copolymer may be melamine aldehyde crosslinked or isocyanate crosslinked. In addition, in this invention, a hydroxyl value says the value measured based on JIS-K0070.

In the present invention, the resin coating material preferably contains a fluorine-containing resin as described above.
As a result, the vinyl-based copolymer having a hydroxyl value of 1 to 100 (KOHmg / g) used as the coating resin for the core material in the present invention is excellent in binding property and originally excellent in releasability. By mixing with fluorine-containing resin,
The vinyl-based copolymer having a hydroxyl group improves the spent resistance of the carrier due to the outstanding effect of exposing the fluororesin on the surface of the carrier coating by the action of the vinyl copolymer.

The fluorine-containing resin contained in the resin coating material used in the present invention together with the vinyl copolymer having a hydroxyl value is polyvinyl fluoride, polyvinylidene fluoride,
Perfluoropolymers such as polytrifluoroethylene and polytrifluorochloroethylene, polytetrafluoroethylene, polyperfluoropropylene, copolymers of vinylidene fluoride and acrylic monomers, vinylidene fluoride and trifluorochloroethylene, Copolymer of tetrafluoroethylene and hexafluoropropylene, copolymer of vinyl fluoride and vinylidene fluoride, copolymer of vinylidene fluoride and tetrafluoroethylene, vinylidene fluoride and hexafluoro Copolymer with propylene,
Fluoroterpolymers such as terpolymers of tetrafluoroethylene with vinylidene fluoride and non-fluorinated monomers are preferably used.

The mixing ratio of the fluorine-containing resin and the vinyl resin having a hydroxyl group, specifically, the ratio (weight ratio) of the fluorine-containing resin and the vinyl resin having a hydroxyl group is preferably 5: 95 to 95: 5, and more preferably 10:90 to 90:10. When the content of the fluororesin is less than 5% by weight, the exposed amount of the fluororesin in the uniform resin coating layer tends to be insufficient, while when the content of the fluororesin exceeds 95% by weight. Since the amount of the vinyl resin having a hydroxyl group is small, the adhesiveness of the resin coating layer to the core material tends to decrease.

The weight average molecular weight of the fluorine-containing resin is preferably 50,000 to 400,000, more preferably 1
It is preferably from 0,000 to 250,000. If it is less than 50,000, the abrasion resistance tends to be insufficient, and 400,
If it exceeds 000, uniform coating on the carrier material becomes difficult.

The monomer ratio of the acrylic component used in the present invention is 30 to 90% by weight, 30,000 to 7,000.
Weight average molecular weight of 0 and weight average molecular weight of 2 to 10 /
The styrene-acrylic copolymer having a number average molecular weight (Mw / Mn) refers to a copolymer of a styrene derivative and acrylic acid esters and a copolymer of a styrene derivative and methacrylic acid esters. These styrene-
The following compounds may be mentioned as specific examples of the monomer constituting the acrylic copolymer. That is, as the styrene derivative, styrene, o-methylstyrene, m
-Methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn -Octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene, o- Examples thereof include nitrostyrene and p-nitrostyrene.

Examples of acrylic acid esters include, for example:
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, propyl acrylate,
Examples thereof include n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate.

Examples of the methacrylic acid esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, and 2-ethylhexyl methacrylate. , Stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like.

In the present invention, the monomer ratio of the acrylic component in the styrene-acrylic copolymer as the coating resin must be 30 to 90% by weight, preferably 40 to 90% by weight, as described above. Is. 30% by weight
If it is less than the above range, the coating uniformity sufficient to contribute to the present invention cannot be obtained, and the toner has insufficient charge stability. Also, 90% by weight
If the amount is larger, uniform coverage is obtained, but the strength against impact resistance is insufficient.

Further, the weight average molecular weight of the above-mentioned copolymer which can be used for the coating resin of the carrier core material of the present invention is required to be 30,000 to 70,000, preferably 30,000 to 60,000, and the weight average molecular weight is good. / The number average molecular weight (Mw / Mn) needs to be 2 to 10, and preferably 2 to 8. When the weight average molecular weight is less than 30,000, sufficient strength with respect to impact resistance of the carrier cannot be obtained, and when it is more than 70,000, the coverage to the carrier core is deteriorated, and the strength of the carrier and further the charging stability become poor. . More importantly, at this time, even if the weight average molecular weight is within this range, the weight average molecular weight / number average molecular weight (Mw / M
If n) is not within the range of 2 to 10, the effect of the present invention cannot be obtained. Weight average molecular weight / number average molecular weight (Mw
If / Mn) is less than 2, the coating resin is uniformly coated, but the impact resistance is poor. If the weight average molecular weight / number average molecular weight (Mw / Mn) is larger than 10, the uniformity of the coating on the carrier core becomes poor, and the strength of the carrier and desired charge stability cannot be obtained.

In the present invention, the resin coating material preferably contains a fluorine-containing resin as described above.
As a result, the fluororesin is uniformly dispersed in the resin coating material, so that the charging characteristics and the spent resistance can be uniformly obtained.

As the fluorine-containing resin to be contained in the resin coating material used in the present invention together with the specific styrene-acrylic copolymer, the above-mentioned resin coating material may be contained in combination with the vinyl copolymer having a hydroxyl value. The same thing as a fluororesin can be mentioned.

The mixing ratio of these fluorine-containing resin and styrene acrylic polymer is preferably 5:95 to 95: 5 in weight ratio (weight of the fluorine-containing resin: weight of the copolymer). More preferably 10:90 to 90:10
Good to be. Within the range of the above content, the desired charge stability can be obtained with either positive or negative polarity developer, but when the content of the fluorine-containing resin is less than 5% by weight,
The charge stability of the developer exhibiting a positive charging property is reduced,
When the content of the fluorine-containing resin exceeds 95% by weight, not only the charge stability of the developer exhibiting the negative charging property is deteriorated but also the leakage property is deteriorated, so that the core material is uniformly applied. Is difficult.

The weight average molecular weight of the fluorine-containing resin is preferably 50,000 to 400,000, more preferably 10
0000-250,000 is good. Weight average molecular weight is 50
If it is less than 000, the impact resistance tends to be insufficient, and if the weight average molecular weight exceeds 400000, uniform coating on the core material becomes unstable.

In the present invention, the molecular weight and molecular weight distribution of the coating resin which can be used as the resin coating material for the carrier core material, and the molecular weight of the fluorine-containing resin are the monodisperse standard polystyrene by GPC (gel permeation chromatography). It is the value obtained by observing the calibration curve obtained by use. The measurement conditions are shown below. Apparatus: GPC-150C (Waters) Column: Showdex KF 7 series (Showa Denko) Temperature: 40 ° C Solvent: THF (tetrahydrofuran) Flow rate: 1.0 ml / min Sample: 0.45 ml of 0.15% sample Injection

The quaternary ammonium salt used in the present invention may be contained inside the toner as a positive charge control agent for the toner, but the effect of the present invention is that other general positive charge control agents are used. Can not be expressed in.

The quaternary ammonium salt used in the present invention is represented by the following general formula (I).

[0071]

[Outside 15] In the formula, R ₁ , R ₂ , R ₃ and R _{4, which} may be the same or different, each represents an alkyl group, an aryl group or an aralkyl group, and A represents an organic anion or a polyacid ion. Specific examples of the organic anion and polyacid ion include an organic sulfate ion, an organic sulfonate ion, an organic phosphate ion, a carboxylate ion and a polyacid ion. Among them, the organic anion is more preferable, and the aromatic is more preferable. Group anions are good.

The reason is that it is difficult to dissolve in water or insoluble in the fourth.
The use of a quaternary ammonium salt is a major feature of the present invention, and the use of A as the above-mentioned anion makes it difficult to dissolve in water.
It becomes a primary ammonium salt, and has the property of not being eluted or desorbed under high humidity. Further, in the present invention, this quaternary ammonium salt is used as a mixture with an insulating resin material, but it is preferable that it is sparingly soluble in water from the viewpoint of improving compatibility with the resin and uniform mixing. Of.

The alkyl group, aryl group or aralkyl group for R ₁ , R ₂ , R ₃ and R ₄ has 1 to 2 carbon atoms.
It is preferably 0, more preferably 1 to 18 carbon atoms.

The quaternary ammonium salt used in the present invention can be roughly classified into two types, R ₄ is an alkyl group type and R ₄ is an aryl group or an aralkyl group type.

In the present invention, a method for preparing a carrier coating solution by dispersing a quaternary ammonium salt in a solution in which the resin material is dissolved or dispersed as undissolved particles, and a method for preparing the quaternary ammonium salt in advance There are two methods of preparing a carrier coating solution by mixing an ammonium salt in a solvent in a solution in which a resin material is dissolved or dispersed, and in particular, a quaternary ammonium salt is coated with a resin. The latter is preferred because it can be uniformly dispersed in the material, and accordingly, a sufficient effect can be obtained with a small amount used.

In the latter method, it is necessary to select a solvent in which the quaternary ammonium salt is sufficiently dissolved and which is compatible with the solvent in which the resin is dissolved. Specifically, the quaternary ammonium salt used in the present invention is 1 g / 100 g.
(Solvent) It is necessary to use a solvent having a solubility above.
Ketones, amines with strong polarity as such solvents,
Although alcohols can be mentioned, alcohols can generally be preferably used. However, the selection is not uniquely determined only by the solubility of the quaternary ammonium salt in the solvent, and the compatibility of the resin with the solvent must be taken into consideration.

As described above, it is essential that the quaternary ammonium salt used in the present invention is insoluble or sparingly soluble in water.
When the solubility in water is defined by the weight (g) dissolved in g, the quaternary ammonium salt used in the present invention is 1.0 g.
/ 100 g (H ₂ O, 20 ° C.), preferably 0.3
It is less than g / 100 g (H ₂ O, 20 ° C.).

The method for measuring the solubility in water in the present invention is shown below.

200 g of a quaternary ammonium salt dissolved in 100 g of distilled water was added to an Erlenmeyer flask with a ground stopper, and the container was sealed and shaken in a constant temperature water bath at a temperature of 20 ± 0.5 ° C. and shaken 60 times / min. After shaking for 8 hours at a number, the mixture is filtered using a filter medium such as filter paper, and insoluble matter xg is weighed. 1
The solubility of the quaternary ammonium salt dissolved in distilled water 200 g (quantity) is represented by _{2.00-x (g / 100gH 2} O).

Next, when the above-mentioned quaternary ammonium salt is dissolved in a solvent to prepare a carrier coating solution, the solubility of the quaternary ammonium salt in a solvent is measured by the following method. Adopted the method.

100 g of an arbitrary solvent in an Erlenmeyer flask with a stopper
50.0 g of a quaternary ammonium salt to be dissolved is added, and the container is sealed and shaken in a constant temperature water bath at a temperature of 20 ± 0.5 ° C. for 8 hours at a shaking rate of 60 times / min, and then filtered. Filter with a filter medium such as the above, and measure insoluble matter xg. The solubility (amount) of the quaternary ammonium salt dissolved in 100 g of the solvent is represented by 50.0-x (g / 100 g solvent).

The solubility of the quaternary ammonium salt used in the present invention in any solvent is preferably 10 g / 100 g (solvent) or more, more preferably 5.0.
It is preferably g / 100 g (solvent) or more.

Among the quaternary ammonium salts that can be used in the present invention, specific examples of compounds in which R ₄ in the general formula (I) is an alkyl group are shown below.

[0084]

[Outside 16]

Among the quaternary ammonium salts which can be used in the present invention, specific examples of the compounds of the above-mentioned general formula (I) in which R ₄ is an aryl group or an aralkyl group are shown below.

[0086]

[Outside 17]

[0087]

[Outside 18]

The quaternary ammonium salt in the present invention is
It contains a lake compound as shown in <Example 4> and <Example 10>. This lake compound is obtained by treating a usual quaternary ammonium salt with a common lake agent. Laking agents may include heteropolyacids and polyacids such as phosphotungsten and molybdenum.

The content of the quaternary ammonium salt of the present invention in the resin coating material is preferably 0.5 wt% to 30%.
wt% range, more preferably 1.0 wt% to 20 wt
% Range is good. If the content is less than 0.5 wt%, the effects of resistance to environmental fluctuations and stabilization of the charge amount, which are the features of the present invention, cannot be sufficiently obtained, and the content exceeds 30 wt%. With the amount, it is difficult to uniformly coat the carrier core material.

The insulating resin used in the resin coating material in the present invention may be an insulating resin used in a general carrier coat, or a mixture thereof.

The insulating resin is preferably vinyl resin. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,
4-dimethylstyrene, pn-butylstyrene, p-
tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-chlorostyrene, 3,
Styrene derivatives such as 4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene and p-nitrostyrene, and ethylene and unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated such as butadiene and isoprene Diolefins; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; methacrylic acid and methyl methacrylate, ethyl methacrylate ,
Α-methylene aliphatic monocarboxylic acid esters such as propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate and phenyl methacrylate. Acrylic acid and methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-acrylic acid acrylate Acrylic esters such as chloroethyl and phenyl acrylate; Maleic acid, maleic acid half esters; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl Ethyl ketone, vinyl hexyl ketone, such as vinyl ketones of methyl isopropenyl ketone; N- vinyl pyrrole, N- vinyl carbazole, N
N- such as vinylindole and N-vinylpyrrolidone
Vinyl compounds; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; and acrolein compounds selected and used for polymerization are used.

Acrylic copolymer resins such as styrene-methacrylate copolymers and styrene-acrylate copolymers are preferable because they are excellent in durability and have a long service life.

In particular, it is effective to copolymerize an acrylic resin containing a hydroxyl group from the viewpoint of the adhesiveness to the carrier core material and the action of exposing the quaternary ammonium salt of the present invention on the carrier surface.

Examples of the acrylic resin monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxy-3-phenyloxypropyl acrylate, and methacrylic acid 2. -Hydroxyethyl, 2-hydroxypropyl methacrylate, hydroxybutyl methacrylate, 2-hydroxy-3 methacrylate
-Phenyloxypropyl. These monomers have a copolymer hydroxyl value of 1 to 100 (KOH
The range is preferably mg / g), more preferably 5 to 70.

In the present invention, examples of the resin used as the binder resin constituting the carrier core material include all resins obtained by polymerizing vinyl monomers. Examples of the vinyl-based monomer here include styrene and o-
Methyl styrene, m-methyl styrene, p-methyl styrene, p-phenyl styrene, p-ethyl styrene,
2,4-dimethylstyrene, pn-butylstyrene,
p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-chloro. styrene,
3,4-dichlorostyrene, m-nitrostyrene, o-
Styrene derivatives such as nitrostyrene and p-nitrostyrene, ethylene and unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; unsaturated diolefins such as butadiene and isoprene; vinyl chloride, vinylidene chloride, vinyl bromide , Vinyl halides such as vinyl fluoride; vinyl acetate, vinyl propionate,
Vinyl esters such as vinyl benzoate; methacrylic acid and methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate. , Stearyl methacrylate, phenyl methacrylate and other α-
Methylene aliphatic monocarboxylic acid esters; acrylic acid and methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, Stearyl acrylate,
Acrylic acid esters such as 2-chloroethyl acrylate and phenyl acrylate; Maleic acid, maleic acid half ester; 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 compounds such as N-vinyl prol, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone; vinyl naphthalenes; acrylonitrile, methacryl Examples thereof include acrylic acid or methacrylic acid derivatives such as ronitrile and acrylamide; acrolein, and the like, and one obtained by polymerizing one or more of these is used.

In addition to resins obtained by polymerizing vinyl monomers, non-vinyl condensation resins such as polyester resins, epoxy resins, phenol resins, urea resins, polyurethane resins, polyimide resins, cellulose resins and polyether resins, or these resins. And a mixture of the above vinyl-based resin can be used.

Examples of the magnetic material used for the magnetic fine particles constituting the carrier core material in the present invention include ferromagnetic metals such as iron, cobalt and nickel, and strong iron such as ferrite, magnetite and hematite, iron, cobalt and nickel. Examples include alloys or compounds containing an element exhibiting magnetism. The saturation magnetization of the magnetic fine particles used in the present invention is 60 emu / g when the magnetic field is 10 K oersted.
It is preferable that it is above. The saturation magnetization is 60 emu /
If it is less than g, even if the content of the magnetic fine particles is increased, carrier tends to easily adhere to the electrostatic image carrier. The magnetic force is measured by V manufactured by Toei Kogyo Co., Ltd.
SM was used.

The above-mentioned magnetic fine particles used in the present invention preferably have a primary average particle diameter of 2.0 μm or less. When the primary average particle diameter exceeds 2.0 μm, the surface of the core material does not become dense, and the coating of the carrier core material used in the present invention with the coating resin tends not to be in a uniform state. there were. Further, in the carrier of the present invention, the content relative to the total amount of the carrier is preferably 30% by weight or more,
More preferably, it is 50% by weight or more. 30
If it is less than wt%, the carrier tends to adhere to the electrostatic image carrier, and it becomes difficult to control the specific resistance of the carrier.

One of the important characteristics of the carrier in which the magnetic material of the present invention is dispersed is the toner charge amount controllability. By using the above resin coating material in the present invention, the specific resistance of the carrier can be controlled appropriately, and the charge-up phenomenon of the toner can be prevented especially under low humidity.

The specific resistance of the magnetic fine particles is preferably 10 ⁹ Ω · cm or less for controlling the specific resistance of the carrier in the present invention. The measurement of the specific resistance of the magnetic fine particles was in accordance with the method for measuring the specific resistance of the carrier described later.

The average particle size of the carrier used in the present invention is 10
It is preferably used in the range of -60 μm. If the carrier particle size is less than 10 μm, the carrier tends to adhere to the electrostatic image carrier, and if it exceeds 60 μm, the share of the developer in the developing device becomes large, resulting in deterioration of the developer, especially toner. There is a tendency that the external additive of the particles is easily peeled off and the shape is changed. Further, if the particle size is large, the amount of toner that can be retained in the composition as a developer becomes small because the surface area becomes small, and an image lacking in fineness tends to be formed. The particle diameter of the carrier used in the present invention is indicated by the maximum chord length in the horizontal direction, and the measurement method is a microscope method in which 300 or more carriers are randomly selected and the diameter thereof is measured to obtain the carrier particle diameter of the present invention. .

The true specific gravity of the carrier of the present invention is 1.5 to 5.
A range of 0 is preferred. More preferably 1.5 to 4.5
It is. If the true specific gravity exceeds 5.0, the load on the developer in the developing device increases, which is not preferable from the viewpoint of deterioration of the developer. If the true specific gravity is less than 1.5, it is practically difficult to obtain a magnetic force sufficient to suppress carrier adhesion to the electrostatic image carrier. The true specific gravity of the carrier used in the present invention was determined by using Trudencer (manufactured by Seishin Enterprise Co., Ltd.).

The specific resistance of the carrier used in the present invention is 10 ⁷
The range of about 10 ¹⁴ Ω · cm is preferable. Resistivity is 10 ⁷ Ω
If it is less than cm, current leaks from the sleeve to the surface of the electrostatic image carrier in the developing area in the developing method in which a bias voltage is applied, and as a result, it is difficult to obtain a good image. When the specific resistance exceeds 10 ¹⁴ Ω · cm, a charge-up phenomenon is caused under a condition such as low humidity, which causes image deterioration such as density density, transfer failure, and fog.

In the present invention, the measurement of the specific resistance is carried out by the method shown in FIG.
The measurement method as described above was used. That is, the cell A is filled with a carrier, the electrodes 1 and 2 are arranged so as to be in contact with the outer filled carrier, a voltage is applied between the electrodes, and the current flowing at that time is measured to obtain a specific resistance ρ (Ω. .Cm) was used. In the above measuring method, since the carrier is powder, the filling rate may change, and the specific resistance may change accordingly, which requires caution. The measurement conditions of the specific resistance in the present invention are: contact area S between the filled carrier and the electrode S = about 2.3 cm ² , thickness = 1 mm, load 275 g on the upper electrode 2, and applied voltage 100V.

In view of keeping the specific resistance of the carrier of the present invention within the above range, by coating a low-resistance core material containing magnetic fine particles with the coating resin of the present invention, the specific resistance can be easily adjusted. It is an advantage of the present invention that it can be controlled to. It is an advantage of the present invention that the specific resistance can be controlled by making the coating structure a uniform coating. That is, the surface exposed state of the magnetic fine particles in the core material, the coating state of the coating resin is closely related to the characteristics of the carrier, for example,
Even if the measured resistance is the same, if there is a part where the resistance is partially low as a carrier, the image tends to be disturbed. Therefore, in order to obtain good developability, it is necessary to keep the resistance of each part of the carrier surface substantially uniform by uniform resin coating.

In order for the resistance of each part of the core material surface to be uniform, it is considered preferable that the magnetic fine particles are uniformly dispersed in each part of the core material surface. When the dispersion state of the magnetic fine particles in the core material is observed with a scanning electron microscope, the carrier in the present invention shows that the magnetic fine particles are uniformly dispersed in each part of the core material surface, and at least one of the magnetic fine particle surfaces is The present inventors have found that the part is substantially exposed on the surface of the core material.

Sphericity of carrier of the present invention (major axis / minor axis)
Is preferably 2 or less. When the sphericity of the carrier of the present invention exceeds 2, the carrier has the effect of reducing the share of the developer,
There was a tendency that the effect of improving the fluidity as a developer was reduced. Therefore, the sphericity is preferably 2 or less in order to impair the effects of preventing the deterioration of the developer and improving the developing characteristics that can be achieved by the carrier of the present invention.

As means for achieving the sphericity of 2 or less in the carrier of the present invention, there are a method of heating the core material to heat-melt the surface to make it spherical, a method of mechanically making it spherical, or a method of preparing the core material. Usually, a magnetic material fine particle, a polymerization initiator, a suspension stabilizer and other additives are added to a monomer solution of a binder resin used for a core material, dispersed and then granulated and polymerized to obtain a core material. The method using the suspension polymerization method of is mentioned.

Next, a method for manufacturing the carrier of the present invention will be described.

The method for producing a carrier of the present invention comprises two steps of forming a core material and then coating with a resin.

First, as a method for preparing the core material, the binder resin and the magnetic fine particles are mixed in a desired quantitative ratio, and, for example,
A method of kneading at a suitable temperature using a heating and melting mixer such as a three-roll or an extruder, cooling and then pulverizing and classifying the binder resin dissolved in a soluble solvent. After mixing into a slurry, a method of granulating and drying using a spray dryer,
Another example is a suspension polymerization method in which magnetic fine particles, a polymerization initiator, a suspension stabilizer and the like are added to a monomer solution of a binder resin for a core material, and the mixture is dispersed, followed by granulation polymerization. In particular, according to the above-mentioned polymerization method, it is not only easy to control the sphericity to 2 or less, but also the magnetic fine particles are uniformly dispersed in each part of the core material surface, and the magnetic fine particle surface Since it is possible to control at least a part of the core material to be substantially exposed on the surface of the core material, it is a more preferable method for preparing the core material to obtain the effects of the present invention.

Next, as a method for coating the core material with resin,
Considering that the core material is made of resin, a treatment method in which the coating resin is rapidly coated so that the core materials do not adhere to each other is preferable, and the selection of the solvent that dissolves the coating resin and the treatment temperature, time, etc. A treatment method in which coating and drying are simultaneously carried out in such a manner that the conditions are sufficiently controlled and the core material is always allowed to flow is preferably used. The coating amount of the resin coating material depends on the true specific gravity of the carrier core material, and when the true specific gravity of the carrier is X, it is preferable that the optimum value of the coating amount of the resin coating material satisfies the following relational expression.

1 / 2X ≦ resin coating material coating amount ≦ 50 / X (wt%) More preferably, 1 / X ≦ resin coating material coating amount ≦ 25 / X (wt%).

That is, the resin coating material coating amount is 1 / 2X
If the amount is less than wt%, the resin coating material coating amount is small,
It is difficult to coat the surface of the core material uniformly, and even if it can be coated, it cannot be a carrier with sufficient strength. On the other hand, if it exceeds 50 / X% by weight, it is difficult to coat the resin coating material uniformly because the coating amount of the resin coating material is too large, and the excess resin coating material tends to exist alone in the carrier. come. Therefore, it is not only difficult to control the resistance to the optimum value, which is a feature of the present invention,
Deterioration of the developability tends to occur due to adhesion of the excess resin coating material in the developer to the electrostatic image carrier.

When the resin coating material contains a quaternary ammonium salt, the method of dispersing the quaternary ammonium salt in the carrier coating solution used in the present invention is as follows. As it is, it is dispersed in the carrier coating solution, and the quaternary ammonium salt is pre-dissolved in an arbitrarily selected solvent and then mixed with the carrier coating solution, and further thoroughly mixed with a mixer to dissolve the companion solutions. It can be performed by a method of dispersing a quaternary ammonium salt.

The former method has an advantage that any one of the quaternary ammonium salts of the present invention can be used and the range of selection is wide.

On the other hand, the latter method has a narrow selection range because the quaternary ammonium salt is limited to those which can be dissolved in the solvent, but has the following advantages.

By dissolving the quaternary ammonium salt, not only the superior effect can be obtained with a smaller amount than the former method in which the quaternary ammonium salt is simply dispersed as particles in a non-dissolved state, but also the quaternary ammonium salt is dissolved. Since it is considered that they are microscopically dispersed in the resin molecular chain and are present in a uniform state, the triboelectric charging ability with the toner is improved at the same contact opportunity as compared with the case where they are simply dispersed. Therefore, it is possible to accelerate the rise of the charging of the toner.

The two-component type developer for developing an electrostatic image of the present invention contains the above-mentioned carrier in which the magnetic material is dispersed in the toner 10.
It is preferable to use it in a mixture of 10 to 1000 parts by weight, more preferably 30 to 500 parts by weight, based on parts by weight.

The toner used in the present invention has a weight average particle diameter of preferably 1 to 20 μm, more preferably 4
˜13 μm, more preferably 4 to 10 μm.

Further, in terms of resolution and toner consumption, the toner used in the present invention preferably has a toner particle size distribution within the following range.

That is, toner particles having a particle size of 5 μm or less account for 17 to 60% by number of all particles, and 8 to 12.7 μm.
It is preferable that toner particles having a particle size in the range of 1 to 30% by number of the total number of particles and particles in the range of a particle size of 16 μm or more are less than 2.0% by volume of the total number of particles.

The preferable constitution of the toner used in the present invention will be described in more detail.

As described above, the toner particles having a particle diameter of 5 μm or less are preferably 17 to 60% by number of the total number of particles, preferably 25 to 50% by number, and more preferably 30 to 30% by number.
50% by number is good. 1 toner particle having a particle size of 5 μm or less
If it is less than 7% by number, the number of toner particles effective for high image quality is small, and particularly as the toner is used by continuing copying or printing out, the effective toner particle component decreases, and the toner particle size distribution is balanced. It deteriorates and the image quality gradually deteriorates. If it exceeds 60% by number, toner particles are likely to aggregate with each other, resulting in toner lumps having a particle size equal to or larger than the original particle size, resulting in rough image quality, lower resolution, and edge portions of the latent image. The density difference from the inside becomes large, and the image tends to be transparent.

As described above, the toner particles having a particle diameter in the range of 8 to 12.7 μm are 1 to 30% by number, preferably 1 to 23%.
It is preferable that the number is%, and more preferably 8 to 20%. If it is more than 23% by number, in particular, if it exceeds 30% by number, the image quality is deteriorated and more than necessary development (that is, excessive toner overload) occurs, resulting in an increase in toner consumption. On the other hand, if it is less than 1% by number, it becomes difficult to obtain a high image quality density. Between the number% (N%) and the volume% (V%) of the toner particle group having a particle size of 5 μm or less, N / V
= −0.04N + k, and 4.5 ≦ k ≦ 6.
A positive number in the range of 5 is shown. Preferably 4.5 ≦ k ≦ 6.
0, and more preferably 4.5 ≦ k ≦ 5.5. As indicated above, 17 ≦ N ≦ 60, preferably 25 ≦ N ≦ 5
0, and more preferably 30 ≦ N ≦ 50.

When k <4.5, the number of toner particles having a particle size smaller than 5.0 μm is small and the image density, resolution and sharpness are poor. The proper presence of fine toner particles, which has been conventionally considered unnecessary, contributes to the close packing of toner in development and formation of a uniform image without roughness. In particular, by uniformly filling the fine lines and the contours of the image, the sharpness is further enhanced visually. When k <4.5, these properties are inferior due to the lack of the particle size distribution component.

From another aspect, it is necessary to cut a large amount of fine powder by means such as classification in order to satisfy the condition of k <4.5 in production, which is disadvantageous in terms of yield and toner cost. Will be things. When k <6.5, the image density tends to decrease during repeated copying due to the presence of fine powder more than necessary. Such a phenomenon is caused by excessively powdered non-magnetic toner particles, which are charged more than necessary, charged and adhered on the developing sleeve and / or carrier, so that normal non-magnetic toner is carried and charged on the developing sleeve or carrier. It is considered to be caused by inhibiting application.

As described above, the toner particles having a particle diameter of 16 μm or more are preferably less than 2.0% by volume, more preferably 1.0% by volume or less, further preferably 0.5% by volume.
% By volume or less. If it is more than 2.0% by volume, not only does it hinder the reproduction of fine lines, but also rough toner particles of 16 μm or more are prominently present on the thin layer surface of the toner particles developed on the photoconductor during transfer. The irregular contact between the electrostatic charge image carrier via the toner layer and the transfer sheet causes irregular transfer conditions, which causes a defective transfer image.

The weight average particle size and particle size distribution of the toner can be measured by various methods, but in the present invention, it was measured using a Coulter counter.

As a measuring device, a Coulter counter T
Interface (made by Nikkaki) and CX that output number distribution and volume distribution using A-II type (made by Coulter)
-1 Connect a personal computer (Canon),
As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. As a measuring method, the electrolytic aqueous solution 100 to
0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 150 ml, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the Coulter counter TAII type was used, and an aperture of 100 μm was used as an aperture.
The particle size distribution of the ~ 40 μm particles was measured and the values according to the invention were then determined.

As the binder resin used in the toner used in the present invention, the following binder resin for toner can be used when a heating / pressurizing roller fixing device having a device for applying oil is used. .

For example, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and their substitution products; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-
Vinyl naphthalene copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer: polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin can be used.

In the heating and pressure roller fixing method in which oil is hardly applied, the offset phenomenon in which a part of the toner image on the toner image support member is transferred to the roller and the adhesion of the toner to the toner image support member are important. It's a problem.
Toners that fix with less heat energy usually tend to be blocked or caked during storage or in a developing device, and therefore these problems must be taken into consideration at the same time. Therefore, in the present invention, when using the heating / pressing roller fixing method in which almost no oil is applied, the selection of the binder resin is more important. Preferred binder resins include crosslinked styrenic copolymers and crosslinked polyesters.

Examples of the comonomer for the styrene monomer of the styrene type copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate,
Double bond such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide A dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate and dimethyl maleate and a substituted product thereof; eg, vinyl chloride, vinyl acetate, vinyl benzoate Vinyl esters such as ethylene; propylene; butylene; ethylene olefins such as vinyl methyl ketone; vinyl hexyl ketone; vinyl ketones such as vinyl methyl ether; vinyl ethyl ether Le, such vinyl ethers vinyl isobutyl ether; such vinyl monomers are used alone or two or more.

As the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, and examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate and ethylene glycol diethylene. Methacrylate, 1,3
A carboxylic acid ester having two double bonds such as butadiol dimethacrylate; divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone divinyl compound; and a compound having three or more vinyl groups; used alone or as a mixture . The crosslinking agent is 0.01 to 10% by weight based on the binder resin.
It is preferable to use a binder resin (preferably 0.05 to 5% by weight) at the time of synthesis in terms of offset resistance and fixing property.

When the pressure-fixing system is used, a binder resin for pressure-fixing toner can be used, and examples thereof include polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer,
There are ethylene-vinyl acetate copolymers, ionomer resins, styrene-butadiene copolymers, styrene-isoprene copolymers, linear saturated polyesters, and paraffins.

In the toner used in the present invention, it is preferable to use charge controllability by blending with toner particles (internal addition) or by mixing with toner particles (external addition). The charge control agent makes it possible to control the optimum charge amount according to the developing system, and particularly in the present invention, it is possible to further stabilize the balance between the particle size distribution and the charge. As described above, it is possible to further clarify the function separation and the mutual complementarity for improving the image quality depending on the particle size range. As the positive charge control agent, a modified product of nigrosine and a fatty acid metal salt; a quaternary ammonium salt such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate; dibutyltin oxide; dioctyltin oxide , Diorganotin oxide such as dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, and dicyclohexyltin borate can be used alone or in combination of two or more kinds. Among these, nigrosine,
Charge control agents such as quaternary ammonium salts are particularly preferably used.

Further, the following general formula (II)

[0139]

[Outside 19] A homopolymer of a monomer represented by: or a copolymer with a polymerizable monomer such as styrene, acrylic acid ester and methacrylic acid ester as described above can be used as a positive charge control agent. In this case, these charge control agents also function as (all or part of) the binder resin.

As the negative charge control agent which can be used in the present invention, for example, an organometallic complex and a chelate compound are effective, and examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate and 3,5-diamine. -T
There is chromium ert-butyl salicylate. Particularly preferred are acetylacetone metal complexes (including monoalkyl-substituted and dialkyl-substituted products), salicylic acid-based metal complexes (including monoalkyl-substituted and dialkyl-substituted products) and salts, particularly salicylic acid-based metal complexes or salicylic acid-based metal salts. Is preferred.

The above-mentioned charge control agent (which does not act as a binder resin) is preferably used in the form of fine particles. In this case, the number average particle size of the charge control agent is
Specifically, it is preferably 4 μm or less (further, 3 μm or less).

When internally added to the toner, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (further 0.2 to 10 parts by weight) per 100 parts by weight of the binder resin.

Fine silica powder is preferably added to the toner used in the present invention. When the toner and the silica fine powder are combined, the wear is remarkably reduced by the presence of the silica fine powder between the toner particles and the carrier or the surface of the sleeve. As a result, the life of the toner and carrier or / and the sleeve can be extended, and the stable chargeability can be maintained, so that the two-component developer having a better toner and carrier can be used for a long period of time. It is possible.

Particularly in the case of the toner having a weight average particle diameter of 10 μm or less, the specific surface area becomes larger than that of the toner having a weight average particle diameter of more than 10 μm, and the toner particles and the carrier are brought into contact with each other for frictional charging. In this case, the number of contact between the surface of the toner particles and the carrier is increased and the abrasion of the toner particles and the contamination of the carrier are more likely to occur than the toner having a weight average particle diameter of more than 10 μm. Addition of the powder makes it possible to obtain a good two-component developer.

As the silica fine powder, silica fine powder produced by a dry method or a wet method can be used, but from the viewpoint of filming resistance and durability, it is preferable to use the silica fine powder by the dry method.

The dry method mentioned here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halogen compound, for example.

On the other hand, as the method for producing the silica fine powder used in the present invention by the wet method, various conventionally known methods can be applied.

As the silica fine powder referred to herein, anhydrous silicon dioxide (colloidal silica); silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate and zinc silicate can be applied.

Among the above silica fine powders, those having a specific surface area by nitrogen adsorption of 30 m ² / g or more (particularly 50 to 400 m ² / g) measured by the BET method give good results. It is preferable to use 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight of silica fine powder with respect to 100 parts by weight of the toner.

When the toner used in the present invention is used as a positively chargeable toner, silica fine powder added to prevent abrasion of the toner and contamination of the carrier and sleeve surfaces is not negatively chargeable. It is preferable to use the positively chargeable silica fine powder without impairing the charging stability, and when used as the negatively chargeable toner, it is preferable to use the negatively chargeable silica fine powder for the same reason. .

Since the silica fine powder is generally negatively charged, the method for obtaining the positively charged silica fine powder is to use the above-mentioned untreated silica fine powder and at least one nitrogen atom in the side chain. There is a method of treating with a silicone oil having an organo group contained therein, a method of treating with a nitrogen-containing silane coupling agent, or a method of treating with both of them.

The positively chargeable silica used in the present invention is
It has a positive triboelectric charge to the iron powder carrier when measured by the blow-off method.

As the silicone oil having a nitrogen atom in the side chain used for treating the silica fine powder, silicone oil having at least a partial structure represented by the following general formula (III) can be used.

[0154]

[Outside 20] (In the formula, R ₁ represents hydrogen, an alkyl group, an aryl group or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, R ₃ and R ₄ represent hydrogen, an alkyl group or an aryl group, and R ₅ Represents a nitrogen-containing heterocycle.)

In the above formula, the alkyl group, the aryl group, the alkylene group and the phenylene group may have an organo group having a nitrogen atom, and may have a halogen substituent as long as the chargeability is not impaired. You can do it. The silicone oil is 1 to 50 based on silica fine powder.
%, Preferably 5 to 30% by weight is used.

The contained nitrogen silane coupling agent used in the present invention generally has a structure represented by the following formula (IV).

General formula (IV) Rm-Si-Yn (R represents an alkoxy group or halogen, Y represents an amino group or an organo group having at least one nitrogen atom, and m and n are 1 to 3). Is an integer and m + n =
4. )

Examples of the organo group having at least one nitrogen atom include an amino group having an organic group as a substituent, a nitrogen-containing heterocyclic group, or a group having a nitrogen-containing heterocyclic group. As the nitrogen-containing heterocyclic group, there is an unsaturated heterocyclic group or a saturated heterocyclic group, and known ones can be applied. Examples of the unsaturated heterocyclic group include the following.

[0159]

[Outside 21]

Examples of the saturated heterocyclic group are shown below.

[0161]

[Outside 22]

The heterocyclic group used in the present invention is preferably a 5-membered ring or a 6-membered ring in view of stability.

Examples of such treating agents include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane,
Diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, monobutylaminopropyltrimethoxysilane, dioctylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane,
Examples thereof include dibutylaminopropyl monomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine and trimethoxysilyl-γ-propylbenzylamine. Further, as the nitrogen-containing heterocycle, those having the above-mentioned structure can be used, and examples of such a compound include methoxysilyl-γ-propylpiperidine, trimethoxysilyl-γ-propylmorpholine, trimethoxysilyl-γ-propylimidazole. Is mentioned. The silane coupling agent is preferably used in an amount of 1 to 50% by weight, more preferably 5 to 30% by weight, based on the fine silica powder.

The amount of the treated positive or negative silica fine powder applied was 0.0 with respect to 100 parts by weight of the toner.
When 1 to 8 parts by weight, the effect is exhibited, and particularly preferably, when 0.1 to 5 parts by weight is added, positive or negative chargeability having excellent stability is exhibited. With respect to the addition form, if a preferable aspect is described, it is 0.1 per 100 parts by weight of the toner.
It is preferable that ~ 3 parts by weight of the treated silica fine powder is attached to the surface of the toner particles. The untreated fine silica powder described above can be used in the same application amount.

The fine silica powder used in the present invention may be treated with a silane coupling agent or a treating agent such as an organic silicon compound for the purpose of making it hydrophobic, if necessary. It is treated with a treatment agent.
Examples of such a treating agent include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane,
Allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, Vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, one for each terminal unit Of S
There is dimethylpolysiloxane containing a hydroxyl group attached to i. These are used alone or in a mixture of two or more. The above treating agent is 1 to 4 based on silica fine powder.
Preference is given to using 0% by weight.

BET specific surface area of 5 instead of silica fine powder
Titanium oxide fine powder (TiO ₂ ) of 0 to 400 m ² / g may be used. Further, a mixed powder of silica fine powder and titanium oxide fine powder may be used.

For the toner used in the present invention, fine powder of a fluorine-containing polymer (for example, fine powder of polytetrafluoroethylene, polyvinylidene fluoride or tetrafluoroethylene-vinylidene fluoride copolymer).
Can also be added. Particularly, fine powder of polyvinylidene fluoride is preferable in terms of fluidity and abrasivity.
The amount of addition to the toner is 0.01 to 2.0 wt%, particularly 0.02 to 1.5 wt% (more preferably 0.02 to 2.0 wt%).
1.0 wt%) is preferable.

As the colorant, conventionally known dyes and / or pigments can be used. For example, carbon black, phthalocyanine blue, peacock blue,
Permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like can be used. The content is 0.1 to 20 parts by weight, preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the binder resin, and 12 to improve the transparency of the OHP film on which the toner image is fixed.
It is preferably not more than 10 parts by weight, more preferably 0.5 to 9 parts by weight.

The toner used in the present invention has a wax form such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sazol wax and paraffin wax for the purpose of improving releasability at the time of heat roll fixing. 0.5 to 5 wt% substance
Addition is one of the preferable forms of the present invention.

If desired, other additives may be added to the toner used in the present invention.

To prepare the toner used in the present invention, a vinyl-based or non-vinyl-based thermoplastic resin, if necessary, a pigment or dye as a colorant, a charge control agent, and other additives are mixed by a ball mill. After sufficiently mixing by a machine, a heating roll, a kneader, a heat kneader such as an extruder is used to melt, knead and knead the meat to make the resins or pigments or dyes dispersed or dissolved in the resin to make them compatible with each other.
After cooling and singulation, pulverization and strict classification can be performed to obtain toner particles. The toner particles can be used as a toner as they are, but if necessary, an external additive such as silica fine powder is added to the obtained toner particles, and the toner particles and the external additive are added using a mixer such as a Henschel mixer. A toner can be obtained by mixing and.

Next, the image forming method according to the present invention will be described with reference to the developing device shown in FIG.

The electrostatic image carrier 11 is an insulating drum for electrostatic recording or α-Se, CdS, ZnO ₂ , OPC, α-.
A photosensitive drum or photosensitive belt having a photoconductive insulating material layer such as Si. The electrostatic image carrier 11 is rotated in the direction of arrow a by a driving device (not shown). Reference numeral 22 denotes a developing sleeve as a developer holding body which is close to or in contact with the electrostatic image carrier 11, and is made of, for example, aluminum,
It is made of a non-magnetic material such as SUS316. The developing sleeve 22 has a horizontally elongated opening formed in the lower left wall of the developing container 36 in the longitudinal direction of the container so that a substantially right half peripheral surface projects into the container 36, and a substantially left half peripheral surface is exposed to the outside of the container so as to be rotatably supported. It is installed horizontally and is driven to rotate in the direction of arrow b.

Reference numeral 23 denotes a developing sleeve (developer holder) 22.
It is a fixed permanent magnet (magnet) as a fixed magnetic field generating means that is inserted into the inside and positioned and held in the position and orientation shown in the figure, and even if the developing sleeve 22 is driven to rotate, this magnet 23 is used.
Is fixedly held as it is in the illustrated position and orientation. The magnet 23 has four magnetic poles: an N-pole magnetic pole 23a, an S-pole magnetic pole 23b, an N-pole magnetic pole 23c, and an S-pole magnetic pole 23d. The magnet 23 may be provided with an electromagnet instead of a permanent magnet.

Reference numeral 24 designates a base portion fixed to the side wall of the container on the upper edge side of the developer supply device in which the developing sleeve 22 is arranged, and the front end side is projected to the inside of the container 36 from the position of the upper edge of the opening to open the upper edge of the container. A nonmagnetic blade as a developer regulating member arranged along the length, for example, SUS316 bent into a V-shaped cross section.

Reference numeral 26 is a magnetic carrier limiting member whose upper surface is in contact with the lower surface side of the non-magnetic blade 24 and whose front end surface is the developer guide surface 261. The portion formed by the non-magnetic blade 24, the magnetic carrier limiting member 26, and the like is the restriction portion.

27 is a carrier of the present invention in which a resin coating material is coated on a carrier core material in which magnetic fine particles are dispersed in a binder resin. 37 is a non-magnetic toner.
Reference numeral 40 denotes a seal member for sealing the toner accumulated in the lower portion of the developing container 36, which has elasticity and is bent in the rotation direction of the developing sleeve 22, and elastically presses the surface side of the developing sleeve 22. The seal member 40 has an end portion on the downstream side in the sleeve rotation direction in the contact area with the developing sleeve so as to allow the developer to enter the inside of the container.

Reference numeral 30 denotes a scattering prevention electrode plate for preventing the scattering by causing the floating developer generated in the developing process to adhere to the electrostatic image carrier by applying a voltage having the same polarity as that of the developer.

Reference numeral 60 denotes a toner concentration detection sensor (not shown)
Is a toner supply roller that operates according to the output obtained from the toner supply roller. As the sensor, the developer volume detection method,
A piezoelectric element, an inductance change detection element, an antenna system using an alternating bias, and a system for detecting optical density can be used. The non-magnetic toner 37 is supplied by stopping the rotation of the roller. The fresh developer supplied with the non-magnetic toner 37 is mixed and stirred while being conveyed by the first screw 61. Therefore, tribo is imparted to the refilled non-magnetic toner during this conveyance. Reference numeral 63 is a cut-off plate, which is cut out at both ends in the longitudinal direction of the developing device, and the fresh developer conveyed by the first screw 61 is transferred to the second screw 62 at this portion.

The S magnetic pole 23d is a carrier pole. The collected developer after the development is collected in the container, and the developer in the container is further conveyed to the regulation unit.

In the vicinity of 23d, the fresh developer conveyed by the second screw 62 provided close to the developing sleeve 22 and the recovered developer after development are exchanged.

Reference numeral 64 is a conveying screw for equalizing the amount of developer in the axial direction of the developing sleeve.

The distance d between the end of the non-magnetic blade 24 and the surface of the developing sleeve 22 is 100 to 900 μm, preferably 1
It is 50 to 800 μm. If this distance is less than 100 μm, the magnetic particles to be described later are clogged between them and the developer layer is likely to have unevenness, and the developer necessary for good development cannot be applied, so that the developed image with a thin density and unevenness is formed. There is a drawback that can only be obtained. d is preferably 400 μm or more in order to prevent uneven coating (so-called blade clogging) due to useless particles mixed in the developer. 9
If it is larger than 00 μm, the amount of the developer applied onto the developing sleeve 22 increases and the predetermined developer layer thickness cannot be regulated, the magnetic particles adhere to the latent image carrier more, and the circulation of the developer described later, There is a drawback that the restriction of development by the developer limiting member 26 is weakened, toner tribo is insufficient, and fogging is likely to occur.

When the imaginary line connecting the center of the developing sleeve 22 and the magnetic pole 23a is L _1, and the imaginary line connecting the center of the developing sleeve 22 and the tip of the non-magnetic blade 24 as the developer regulating member is L ₂ , The angle formed by the virtual lines L ₁ and L ₂ is θ ₁ .

This angle θ ₁ is -5 ° to 35 °, preferably 0 ° to 25 °. When θ ₁ <−5 °, the thin developer layer formed by the magnetic force, mirroring force, cohesive force, etc. acting on the developer becomes sparse and uneven, and when θ ₁ > 35 °, it is non-magnetic. With the blade, the amount of developer applied increases, and it is difficult to obtain a predetermined amount of developer.

Even if the developing sleeve 22 is rotationally driven in the direction of the arrow b, this magnetic particle layer balances the magnetic force, the restraining force based on gravity and the conveying force of the scattering sleeve 22 in the moving direction, so that the developing sleeve 22 can be rotated. Movement slows as you move away from the surface. Of course, some fall under the influence of gravity.

Therefore, by appropriately selecting the arrangement positions of the magnetic poles 23a and 23d and the fluidity and magnetic characteristics of the magnetic carrier 27, the magnetic pole layer 2 becomes closer to the developing sleeve 22 as the magnetic particle layer approaches.
It is conveyed in the 3a direction to form a moving layer. Due to the movement of the magnetic carrier 27, the developing sleeve 22 is rotated to be conveyed to the developing area for development.

At this time, the thickness of the developer layer on the developing sleeve 22 may be made equal to or slightly larger than the facing gap distance e between the developing sleeve 22 and the electrostatic image carrier 11, and an alternating electric field may be applied to this gap. preferable. This distance e is 50
~ 800 μm (more preferably 100 to 700 μm)
Is good.

By applying an alternating electric field or a developing bias in which a DC electric field is superimposed on the alternating electric field between the developing sleeve 22 and the latent image carrier 11 by the bias power source, the non-magnetic property from the developing sleeve 22 to the electrostatic image holder 11 is increased. Toner 37
Can be easily moved, and a high quality image can be formed.

The AC electric field as the applied alternating electric field is preferably 2000 Vpp or less, and when the DC electric field is superimposed, it is preferable to apply the DC electric field in the range of 1000 V or less.

The method for measuring the triboelectric charge amount of toner on the carrier of the present invention will be described in detail with reference to FIG.

FIG. 3 is an explanatory diagram of the triboelectric charge amount measuring device. A magnetic brush (deposited with toner) on the developer carrier for measuring the triboelectric charge amount is placed in a metal measuring container 72 having a conductive screen 71 of 400 mesh at the bottom (which can be appropriately changed to a size that does not allow carrier particles to pass). The mixture 73 of the carrier of the present invention is put and the lid 73 made of metal is put. At this time, the total weight of the measurement container 72 is weighed and set as W ₁ (g). Next, in the suction device 74 (at least the portion in contact with the measurement container 72 is an insulator), suction is performed from the suction port 75 to adjust the air volume control valve (76 to adjust the pressure of the vacuum gauge 77 to 70 mmHg. This state is sufficient ( The toner is sucked and removed for about 1 minute.The electric potential of the electrometer 78 at this time is set to V (volt). 79 is a condenser and the capacity is C (μ).
F). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). This triboelectric charge amount Q (μC / g) is calculated by the following equation.

Q (μC / g) = C × V / (W ₁ -W ₂ ) However, the measurement conditions are temperature / humidity of 23 ° C./65% RH.

The present invention will be described below with reference to examples, but the present invention is not limited thereto. Unless otherwise stated, all% and parts in the following formulations are% by weight and Mw is a weight average molecular weight and Mn is a number average molecular weight.

[0195]

【Example】

 (Example 1) ・ Styrene 22.2% ・ 2-Ethylhexyl acrylate 11.1% ・ Reduced iron (particle diameter 0.32 μm) 66.7%

The above materials are heated to a temperature of 70 ° C. in a container,
It was made to melt | dissolve and it was set as the monomer mixture. While maintaining the temperature at 70 ° C., an initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was put into a 2 liter flask containing 1.2 liter of a 1% polyvinyl alcohol (PVA) aqueous solution, and it was placed at 4500 at 70 ° C. with a homogenizer.
The composition was granulated by stirring at rpm for 10 minutes. Then, polymerization was performed at 70 ° C. for 10 hours while stirring with a paddle stirrer. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic substance-dispersed styrene acrylic slurry was washed and filtered.
This was dried to obtain a carrier core material.

The surface of the obtained carrier core material was coated with the following resin coating material. Styrene-2-hydroxyethyl methacrylate-methyl methacrylate copolymer (monomer composition weight ratio = 35:
8:57 hydroxyl value (KOHmg / g) = 30
Weight average molecular weight (Mw) = 52,000 Weight average molecular weight / number average molecular weight (Mw / Mn) = 2.5) 50% -Vinylidene fluoride-tetrafluoroethylene copolymer (monomer composition weight ratio = 75: 25 weight) Average molecular weight (Mw) = 210,000) 50%

10% of the above resin material was dissolved in a mixed solvent of acetone and methyl ethyl ketone (mixing weight ratio = 1: 1) so that the resin coating amount was 0.8% from the above-mentioned calculation formula, and the carrier coating solution was prepared. Was produced. This carrier coating solution is applied by a coating machine (Okada Kogyo Co., Ltd .: Spiracoater)
The carrier core material was applied while simultaneously applying and drying. The obtained carrier core material after coating was dried at a temperature of 90 ° C. for 2 hours to remove the solvent and obtain an electrophotographic carrier in which the surface of the carrier core material was coated with a resin coating material. When the obtained electrophotographic carrier was observed by an electron microscope, it was confirmed that the carrier core material was uniformly coated with the resin, and the magnetic particles were substantially and uniformly exposed on the coated surface. Was done. Table 5 shows the physical properties of the carrier. -Polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 100 parts-Phthalocyanine pigment 5 parts-Chromium complex salt of di-tert-butylsalicylic acid 4 parts

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a three-roll mill three times, cooled, and then coarsely pulverized with a hammer mill to a particle size of about 1 to 2 mm. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain a negatively chargeable cyan powder (toner) having a weight average diameter of 12.3 μm.

100 parts of the cyan powder and 0.4 part of silica fine powder hydrophobized with hexamethyldisilazane were mixed by a Henschel mixer to obtain a cyan toner having silica fine powder on the toner particle surface. Prepared.

This cyan toner and the above electrophotographic carrier were mixed in an environment of temperature / humidity of N / N (23 ° C./60% RH) so that the toner concentration would be 10% to obtain a two-component developer. 100 g of the obtained two-component developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. After that, the two-component developer was taken out, and the developer was observed with an electron microscope. As a result, desorption of the magnetic material from the carrier, peeling of the coating material, and filming by the toner were not observed. Furthermore, detachment of the external additive of the toner,
No burial was observed.

The cyan toner and the electrophotographic carrier were mixed in a temperature / humidity L / L (15 ° C./10% RH) environment so as to have a concentration of 10% to obtain a two-component developer. This is a full-color laser copier CL made by Canon under the same environment.
Put in the developing device for C-1 and drive with external motor (peripheral speed 3
Idle rotation was performed for 30 minutes at (00 rpm). After this, C
An image was printed using LC-1 with a development contrast of 300V. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was good.

The evaluation results are shown in Table 2.

Comparative Example 1 The carrier core material used in Example 1 was used as an electrophotographic carrier without resin coating, and the same measurements and tests as in Example 1 were performed. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

As a result of the shaking test, desorption of the magnetic material from the carrier was observed by observation with an electron microscope.

(Comparative Example 2) [0206] Instead of the carrier core material used in Example 1, 45 µm reduced iron particles were used, and the coating resin used in Example 1 was coated in the same manner as in Example 1 with a coating amount of 0.8%.
Then, a carrier for electrophotography was obtained, and the same measurements and tests as in Example 1 were carried out. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

As a result of the shaking test, the electrophotographic carrier was not changed from that before shaking, but it was observed that the external additive was buried on the toner surface. As a result of the image display test, particularly the halftone part was found to be rough.

Comparative Example 3 Instead of the resin coating material of the carrier used in Example 1 on the carrier core material used in Example 1, vinylidene fluoride-tetrafluoroethylene copolymer (monomer composition weight ratio = 75) : 25 weight average molecular weight (Mw) = 210,000)

Using only the above resin material, 10% was dissolved in a mixed solvent of acetone and methyl ethyl ketone so that the resin coating amount was 1.0% to prepare a carrier coating solution.

The carrier coating solution was applied to the surface of the carrier core material in the same manner as in Example 1 to obtain an electrophotographic carrier in which the surface of the carrier core material was coated with the resin coating material.

Microscopic observation revealed that the carrier core material was not uniformly coated.

Example 1 using this electrophotographic carrier
The same measurement and test as the above were performed. The physical properties of the carrier are shown in Table 1 and the evaluation results are shown in Table 2.

As a result of the shaking test, peeling of the coating material was observed, and some detachment of the magnetic material was also observed. Further, as a result of the image output test, image unevenness occurred.

Example 2 Styrene-2-ethylhexyl acrylate (85 /
Copolymer of 15) 50% ・ Reduced iron 50%

The above materials were sufficiently premixed by a Henschel mixer, melted and kneaded at least twice with a three-roll mill, and after cooling, had a particle size of about 2 using a hammer mill.
It was roughly crushed to about mm. Next, it was pulverized to a particle size of 50 μm by an air jet pulverizer. Further, the obtained finely pulverized product was put into MechanoMill MM-10 (manufactured by Okada Seiko Co., Ltd.) and mechanically spheroidized.

The spheronized finely pulverized particles were further classified to obtain a carrier core material. The particle size of this carrier core material is 4
It was 9 μm.

Example 1 was formed on the surface of the obtained carrier core material.
A resin coating material was coated in the same manner as in 1. to obtain an electrophotographic carrier.

Example 1 using this electrophotographic carrier
The same measurement and test as the above were performed. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

As a result, the shaking test as in Example 1,
The image output test was also good.

Example 3 Polyester resin obtained by condensing ethoxylated bisphenol-fumaric acid-trimellitic acid (50/40/10) 40% Magnetite (particle diameter 0.26 μm) 60%

Using the above materials and in the same manner as in Example 2,
A spherical carrier core material was obtained. The particle size of this carrier core material was 53 μm.

The surface of the obtained carrier core material was coated with the following resin coating material in the same manner as in Example 1. Styrene-2-hydroxymethyl methacrylate-methyl methacrylate-ethyl methacrylate (monomer composition weight ratio = 57: 20: 13: 10 hydroxyl value = 40
Weight average molecular weight (Mw) = 54,000 Weight average molecular weight / Number average molecular weight (Mw / Mn) = 3.2) 40
% ・ Methyl etherified melamine formaldehyde resin 1
0% -Vinylidene fluoride-tetrafluoroethylene copolymer (monomer composition weight ratio = 75:25 weight average molecular weight (Mw) = 210,000) 50%

The above carrier core material was coated in the same manner as in Example 1 using a carrier coating solution prepared by dissolving 10% of the above resin material in a methyl ethyl ketone solution so that the resin coating amount was 1.1%, An electrophotographic carrier was obtained.
When the same measurement and test as in Example 1 were performed, good results were obtained as in Example 1. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

Example 4 A carrier core material was produced in the same manner as in Example 3 except that the amount of magnetite used in Example 3 was 38% (the rest being polyester resin). The resin coating material used in Example 3 was dissolved in 10% in a methyl ethyl ketone solution so that the resin coating amount was 0.9%, and the carrier material was coated as a coating solution in the same manner as in Example 3. , A carrier for electrophotography was obtained. Using this electrophotographic carrier, measurements and tests were carried out in the same manner as in Example 1. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2. The result of the shaking test was as good as that of Example 3, but in the image forming test under low humidity, some carrier adhesion was observed and the solid image density was slightly lower than that of Example 3. It did not cause any particular problems in practical use.

Example 5 Phenol 10.0% Formaldehyde (formaldehyde about 37%, methanol about 10%, balance water) 5.0% Magnetite (particle size 0.25 μm) 85.0%

Ammonia using the above materials as a basic catalyst,
Using calcium fluoride as a polymerization stabilizer, while stirring in an aqueous phase, the temperature was gradually raised to 80 ° C., and polymerization was performed for 2 hours to obtain a carrier core material. The particle size of this carrier core material was 41 μm. The obtained carrier core material was coated in the same manner as in Example 3 with a methyl ethyl ketone solution in which the resin coating material used in Example 3 was dissolved in 10% so that the resin coating amount was 1.0%, and electrophotography was performed. Got a carrier for. When this electrophotographic carrier was used to perform the same measurements and tests as in Example 1, the same good results as in Example 1 were obtained. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

Comparative Example 4 The carrier core material prepared in Example 5 was used as an electrophotographic carrier without coating the resin coating material, and the same measurement and test as in Example 1 were carried out. In the test, desorption of the magnetic substance was observed. Further, in the image output test, the image was distorted, which was considered to be due to the decrease in the applied bias voltage. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

Example 6 Styrene-2-ethylhexyl acrylate-dimethylaminoethyl methacrylate copolymer (monomer composition weight ratio = 80: 15: 5) 100 parts-copper phthalocyanine 4 parts-low molecular weight polypropylene 5 Department

Using the above materials, blue particles having a weight average particle diameter of 11.7 μm were obtained in the same manner as in Example 1. 0.8 parts of positively chargeable colloidal silica treated with amino-modified silicone oil was mixed with 100 parts of the particles by a Henschel mixer to obtain a positively chargeable blue toner.

The above toner and the electrophotographic carrier prepared in Example 5 were mixed so as to have a toner concentration of 8% to prepare a two-component developer, and a copying machine NP-483 manufactured by Canon was used.
The same measurement and test as in Example 1 were performed using No. 5, and in the image forming test, a positive image was excellent and a uniform image was obtained. The physical properties of the carrier are shown in Table 1, and the evaluation results are shown in Table 2.

[0231]

[Table 1]

[0232]

[Table 2]

Example 7 Styrene 22.2% 2-Ethylhexyl acrylate 11.1% Magnetite (particle diameter 0.26 μm) 66.7%

The above materials are heated to a temperature of 70 ° C. in a container,
It was made to melt | dissolve and it was set as the monomer mixture. Further, while maintaining the temperature at 70 ° C., the initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was put into a 2 liter flask containing 1.2 liter of a 1% polyvinyl alcohol (PVA) aqueous solution, and was heated at 70 ° C. by a homogenizer to 450 ° C.
The composition was granulated by stirring at 0 rpm for 10 minutes. afterwards,
Polymerization was carried out at 70 ° C. for 10 hours while stirring with a paddle stirrer. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic substance-dispersed styrene acrylic slurry was washed and filtered. This was dried to obtain a carrier core material. The surface of the obtained carrier core material was coated with the following resin coating material. -Styrene-methyl methacrylate-2-ethylhexyl acrylate copolymer (monomer composition weight ratio = 45: 3)
5:20 weight average molecular weight (Mw) = 41,000 weight average molecular weight / number average molecular weight (Mw / Mn) = 2.5)

10% of the above resin material was dissolved in toluene so that the coating resin amount was 0.8% according to the above calculation formula,
A carrier coating solution was prepared. This carrier coating solution was applied to the above carrier core material while being dried by a coating machine (Okada Seiko Co., Ltd .: Spiracoater).
The obtained carrier core material after coating is dried at a temperature of 40 ° C. for 1 hour to remove the solvent, and then heated at a temperature of 110 ° C. for 2 hours to obtain an electrophotographic carrier in which the surface of the carrier core material is coated with a resin coating material. It was When the obtained electrophotographic carrier was observed by an electron microscope, it was confirmed that the carrier core material was uniformly coated with the resin, and the magnetic particles were exposed substantially uniformly on the coated surface. It was Table 3 shows the physical properties of the above carriers. -Polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 100 parts-Phthalocyanine pigment 5 parts-Chromium complex salt of di-tert-butylsalicylic acid 4 parts

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a three-roll mill three times, cooled, and then coarsely pulverized with a hammer mill to a particle size of about 1 to 2 mm. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain a negatively chargeable cyan powder (toner) having a weight average diameter of 12.3 μm.

100 parts of the cyan powder and 0.4 part of silica fine powder hydrophobized with hexamethyldisilazane were mixed by a Henschel mixer to obtain a cyan toner having silica fine powder on the toner particle surface. Prepared.

This cyan toner and the above electrophotographic carrier were mixed in an environment of temperature / humidity of N / N (23 ° C./60% RH) so that the toner concentration would be 10% to obtain a two-component developer. 100 g of the obtained two-component developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. After that, the two-component developer was taken out, and the developer was observed with an electron microscope. As a result, desorption of the magnetic material from the carrier, peeling of the coating material, and filming by the toner were not observed. Further, neither detachment of the external additive of the toner nor burial was observed.

A cyan toner and the electrophotographic carrier were mixed in an environment of temperature / humidity of L / L (15 ° C./10% RH) so that the toner concentration would be 8% to obtain a two-component developer.
Under the same environment, this was placed in a developing unit for a full color laser copying machine CLC-1 manufactured by Canon, and idling was performed for 30 minutes by driving an external motor (peripheral speed 300 rpm). After that, CLC-1 was used and an image was output with a development contrast of 300V. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was good. Table 4 shows the evaluation results.

Example 8 Styrene 22.2% 2-Ethylhexyl acrylate 11.1% Reduced iron (particle diameter 0.32 μm) 66.7%

The above materials are heated to a temperature of 70 ° C. in a container,
It was made to melt | dissolve and it was set as the monomer mixture. Further, while maintaining the temperature at 70 ° C., the initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was put into a 2 liter flask containing 1.2 liter of a 1% polyvinyl alcohol (PVA) aqueous solution, and was heated at 70 ° C. by a homogenizer to 450 ° C.
The composition was granulated by stirring at 0 rpm for 10 minutes. afterwards,
Polymerization was carried out at 70 ° C. for 10 hours while stirring with a paddle stirrer. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic substance-dispersed styrene acrylic slurry was washed and filtered. This was dried to obtain a carrier core material. The surface of the obtained carrier core material was coated with the following resin coating material. Styrene-2-ethylhexyl methacrylate copolymer (monomer composition weight ratio = 45: 60 weight average molecular weight (Mw) = 42000 weight average molecular weight / number average molecular weight (Mw / Mn) = 2.9)

10% of the above resin material was dissolved in toluene so that the coating resin amount was 0.8% according to the above calculation formula,
A carrier coating solution was prepared. This carrier coating solution was applied to the above carrier core material while being dried by a coating machine (Okada Seiko Co., Ltd .: Spiracoater).
The obtained carrier core material after coating is dried at a temperature of 40 ° C. for 1 hour to remove the solvent, and then heated at a temperature of 110 ° C. for 2 hours to obtain an electrophotographic carrier in which the surface of the carrier core material is coated with a resin coating material. It was When the obtained electrophotographic carrier was observed by an electron microscope, it was confirmed that the carrier core material was uniformly coated with the resin, and the magnetic particles were exposed substantially uniformly on the coated surface. It was Table 3 shows the physical properties of the above carriers.

The cyan toner used in Example 7 and the above electrophotographic carrier were mixed at a temperature / humidity of N / N (23 ° C./60%).
Under a (RH) environment, the toner concentration was adjusted to 10% to obtain a two-component developer. 100 g of the obtained two-component developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. After that, the two-component developer was taken out, and the developer was observed with an electron microscope. As a result, desorption of the magnetic material from the carrier, peeling of the coating material, and filming by the toner were not observed. Further, neither detachment of the external additive of the toner nor burial was observed.

The cyan toner used in Example 7 and the above electrophotographic carrier were mixed at a temperature / humidity of L / L (15 ° C./10%).
Under a (RH) environment, the toner concentration was adjusted to 8% to obtain a two-component developer. Under the same environment, this was put in the developing unit for Canon full-color laser copying machine CLC-1 and driven by an external motor (peripheral speed 300 rpm) to rotate at 30 rpm.
Minutes went. After that, CLC-1 was used and an image was output with a development contrast of 300V. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was good. Table 4 shows the evaluation results.

Comparative Example 5 The same measurements and tests as in Example 8 were carried out using the carrier core material used in Example 8 as an electrophotographic carrier without resin coating. Table 3 shows the physical properties of the carrier, and Table 4 shows the evaluation results.

As a result of the shaking test, desorption of the magnetic material from the carrier was observed by observation with an electron microscope.

(Comparative Example 6) In the same manner as in Example 8, except that the carrier core material used in Example 8 was replaced with reduced iron particles of 43 μm, the coating resin used in Example 8 was coated at 0.8%.
To obtain a carrier for electrophotography. Table 3 shows the physical properties of the obtained carrier. Using this carrier, the same measurements and tests as in Example 8 were performed. Table 4 shows the evaluation results.

As a result of the shaking test, the electrophotographic carrier was not changed from that before shaking, but it was observed that the external additive was buried on the toner surface. As a result of the image display test, particularly the halftone part was found to be rough.

Comparative Example 7 Instead of the resin coating material of the carrier used in Example 8 on the carrier core material used in Example 8, styrene-2-ethylhexyl methacrylate (monomer composition weight ratio = 40: 60 weight) Average molecular weight (Mw)
= 110,000 weight average molecular weight / number average molecular weight (Mw / Mn) = 20.2)

Using the above resin material, the coating resin amount was 0.
A carrier coating solution was prepared by dissolving 10% in toluene to 8%.

The above carrier coating solution was applied to the surface of the carrier core material in the same manner as in Example 8 to obtain an electrophotographic carrier in which the surface of the carrier core material was coated with the resin coating material. When the obtained electrophotographic carrier was observed with an electron microscope, the coated state was not uniform. Using this electrophotographic carrier, the same measurements and tests as in Example 8 were performed. The physical properties of the carrier are shown in Table 3, and the evaluation results are shown in Table 4.
Shown in

As a result of the shaking test, peeling of the coating material was observed, and some detachment of the magnetic material was also observed. Further, as a result of the image output test, image unevenness occurred.

(Example 9) Styrene-2-ethylhexyl acrylate (85 /
Copolymer of 15) 50% ・ Reduced iron 50%

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a three-roll mill at least twice, and after cooling, a particle size of about 2 was obtained using a hammer mill.
It was roughly crushed to about mm. Next, it was pulverized to a particle size of 50 μm by an air jet pulverizer. Further, the obtained finely pulverized product was put into MechanoMill MM-10 (manufactured by Okada Seiko Co., Ltd.) and mechanically spheroidized.

[0255] The spheronized finely pulverized particles were further classified to obtain a carrier core material. The particle size of this carrier core material was 48 μm.

Example 8 was formed on the surface of the obtained carrier core material.
A resin coating material was coated in the same manner as in 1. to obtain an electrophotographic carrier.

Example 8 using this electrophotographic carrier
The same measurement and test as the above were performed. Table 3 shows the physical properties of the carrier, and Table 4 shows the evaluation results.

As a result, a shaking test was conducted in the same manner as in Example 8,
It was good in the image output test.

Example 10 Polyester resin obtained by condensing ethoxylated bisphenol-fumaric acid-trimellitic acid (50/40/10) 40% Magnetite (particle diameter 0.26 μm) 60%

Using the above materials and in the same manner as in Example 9,
A spherical carrier core material was obtained. The particle size of this carrier core material was 54 μm.

The surface of the obtained carrier core material was coated with the following resin coating material in the same manner as in Example 8. Styrene-phenyl acrylate copolymer (monomer composition weight ratio = 50: 50 weight average molecular weight (Mw) = 560
00 Weight average molecular weight / Number average molecular weight (Mw / Mn)
= 4.5)

Using the carrier coating solution prepared by dissolving 10% of the above resin material in toluene so that the coating resin amount was 1.2%, the above carrier core material was coated in the same manner as in Example 8 to prepare an electronic sample. I got a photographic carrier. When the same measurement and test as in Example 8 were carried out, good results were obtained as in Example 8. Table 3 shows the physical properties of the carrier, and Table 4 shows the evaluation results.

Example 11 A carrier core material was produced in the same manner as in Example 10 except that the amount of magnetite in Example 10 was changed to 38% (the rest being polyester resin). The resin coating material used in Example 10 was applied to this with a coating resin amount of 1.2.
% To 10% in toluene, and the carrier core material was coated as a coating solution in the same manner as in Example 10 to obtain an electrophotographic carrier. Using this electrophotographic carrier, measurements and tests were carried out in the same manner as in Example 7.
Table 3 shows the physical properties of the carrier, and Table 4 shows the evaluation results.

The results of the shaking test were as good as in Example 10, but in the image forming test under low humidity, some carrier adhesion was observed, and the solid image density was slightly lower than that of Example 10. However, there was no particular problem in practice.

Example 12 Phenol 10.0% Formaldehyde 5.0% (Formaldehyde about 3%)
7%, about 10% methanol, the rest is water) Magnetite (particle size 0.25 μm) 85.0%

Ammonia using the above materials as a basic catalyst,
Using calcium fluoride as a polymerization stabilizer, while stirring in an aqueous phase, the temperature was gradually raised to 80 ° C. and polymerization was performed for 2 hours to obtain a carrier core material. The particle size of this carrier core material was 38 μm. The resin coating material used in Example 10 was applied to the obtained carrier core material in an amount of coating resin of 1.1.
Coating was performed in the same manner as in Example 10 using a toluene solution in which 10% was dissolved to give a carrier for electrophotography. When this electrophotographic carrier was used for the same measurements and tests as in Example 8, the same good results as in Example 8 were obtained. Table 3 shows the physical properties of the carrier, and Table 4 shows the evaluation results.

(Comparative Example 8) The carrier core material prepared in Example 12 was used as an electrophotographic carrier without being coated with a resin coating material, and the same measurement and test as in Example 8 were carried out. In the test, desorption of the magnetic substance was observed. Further, in the image output test, the image was distorted, which was considered to be due to the decrease in the applied bias voltage. Table 3 shows the physical properties of the carrier, and Table 4 shows the evaluation results.

[0268]

[Table 3]

[0269]

[Table 4]

(Example 13) Styrene 22.2% 2-Ethylhexyl acrylate 11.1% Reduced iron (particle diameter 0.32 μm) 66.7%

The above materials are heated to a temperature of 70 ° C. in a container,
It was made to melt | dissolve and it was set as the monomer mixture. Further, while maintaining the temperature at 70 ° C., the initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was put into a 2 liter flask containing 1.2 liter of a 1% polyvinyl alcohol (PVA) aqueous solution, and was heated at 70 ° C. by a homogenizer to 450 ° C.
The composition was granulated by stirring at 0 rpm for 10 minutes. afterwards,
Polymerization was carried out at 70 ° C. for 10 hours while stirring with a paddle stirrer. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic substance-dispersed styrene acrylic slurry was washed and filtered. This was dried to obtain a carrier core material. The true specific gravity of this carrier core material was 2.4. The surface of the obtained carrier core material was coated with the following resin coating material. -Styrene-2-ethylhexyl methacrylate copolymer (monomer composition weight ratio = 45: 60, weight average molecular weight (Mw) = 42000 weight average molecular weight / number average molecular weight (Mw / Mn) = 2.9) -vinylidene fluoride -Tetrafluoroethylene copolymer (monomer composition weight ratio = 75:25 weight average molecular weight (M
w) = 210000)

The above copolymer was coated with the above material in an amount of 10% in a mixed solvent of acetone and methyl ethyl ketone (mixing weight ratio = 1: 1) so that the resin content was 0.8% according to the above calculation formula.
% Dissolved to prepare a carrier coating solution. This carrier coating solution was applied to the above carrier core material while being dried by a coating machine (Okada Seiko Co., Ltd .: Spiracoater). The temperature of the obtained carrier core material after coating was adjusted to 40
The solvent was removed by drying at 1 ° C. for 1 hour, and then heated at a temperature of 110 ° C. for 2 hours to obtain an electrophotographic carrier in which the carrier core material surface was coated with a resin coating material. When the obtained electrophotographic carrier was observed by an electron microscope, it was confirmed that the carrier core material was uniformly coated with the resin, and the magnetic particles were substantially and uniformly exposed on the coated surface. Was done. Table 3 shows the physical properties of the carrier. -Polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 100 parts-Phthalocyanine pigment 5 parts-Chromium complex salt of di-tert-butylsalicylic acid 4 parts

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a three-roll mill three times, cooled, and then coarsely pulverized with a hammer mill to a particle size of about 1 to 2 mm. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain a negatively chargeable cyan powder (toner) having a weight average diameter of 12.3 μm.

100 parts of the cyan powder and 0.4 part of silica fine powder hydrophobized with hexamethyldisilazane were mixed by a Henschel mixer to obtain a cyan toner having silica fine powder on the toner particle surface. Prepared.

This cyan toner and the above electrophotographic carrier were mixed in an environment of temperature / humidity of N / N (23 ° C./60% RH) so that the toner concentration would be 10% to obtain a two-component developer. 100 g of the obtained two-component developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. After that, the two-component developer was taken out, and the developer was observed with an electron microscope. As a result, desorption of the magnetic material from the carrier, peeling of the coating material, and filming by the toner were not observed. Further, neither detachment of the external additive of the toner nor burial was observed.

The cyan toner and the electrophotographic carrier were mixed in a temperature / humidity L / L (15 ° C./10% RH) environment so that the toner concentration was 10% to obtain a two-component developer. Under the same environment, this was placed in a developing unit for a full color laser copying machine CLC-1 manufactured by Canon, and idling was performed for 30 minutes by driving an external motor (peripheral speed 300 rpm). After that, CLC-1 was used and an image was output with a development contrast of 300V. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was good. Table 6 shows the evaluation results.

(Comparative Example 9) The carrier core material used in Example 13 was used as an electrophotographic carrier without resin coating, and the same measurements and tests as in Example 1 were carried out. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

As a result of the shaking test, desorption of the magnetic material from the carrier was observed by observation with an electron microscope.

(Comparative Example 10) [0279] Instead of the carrier core material used in Example 13, 45 µm reduced iron particles were used, and the coating resin used in Example 13 was coated in the same amount as in Example 13 with a coating amount of 0.8%. And a carrier for electrophotography having a true specific gravity of 7.8. Using this electrophotographic carrier, the same measurements and tests as in Example 13 were performed. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

As a result of the shaking test, the electrophotographic carrier was not changed from that before shaking, but it was observed that the external additive was buried on the toner surface. In addition, as a result of the image output test, the halftone portion was particularly rough.

Comparative Example 11 Instead of the resin coating material of the carrier used in Example 13, the carrier core material used in Example 13 was replaced with vinylidene fluoride-tetrafluoroethylene copolymer (monomer composition weight ratio = 75: 25 Weight average molecular weight (Mw) = 210000) Using only the above resin material, 10% in a mixed solvent of acetone and methyl ethyl ketone (mixing weight ratio = 1: 1) so that the coating resin amount becomes 0.8%. It melt | dissolved and produced the carrier coating solution.

The carrier coating solution was applied to the surface of the carrier core material in the same manner as in Example 1 to obtain an electrophotographic carrier in which the surface of the carrier core material was coated with the resin coating material. When the obtained electrophotographic carrier was observed with an electron microscope, the coated state was not uniform. Using this electrophotographic carrier, the same measurements and tests as in Example 13 were performed. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

As a result of the shaking test, peeling of the coating material was observed, and some detachment of the magnetic material was also observed. Further, as a result of the image output test, image unevenness occurred.

(Example 14) -Styrene-2-ethylhexyl acrylate copolymer (monomer composition weight ratio = 85: 15) 50% -Reduced iron 50%

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a three-roll mill at least two times or more, and after cooling, a particle size of about 2 was obtained using a hammer mill.
It was roughly crushed to about mm. Then, it was pulverized to a particle size of about 50 μm by an air jet pulverizer. Further, the obtained finely pulverized product was mechanomill MM-10 (manufactured by Okada Seiko Co., Ltd.)
And spheronized mechanically.

The pulverized finely pulverized particles were further classified to obtain a carrier core material. The particle size of this carrier core material was 48 μm.

Example 1 was formed on the surface of the obtained carrier core material.
A resin coating material was coated in the same manner as in 3 to obtain an electrophotographic carrier. Using this electrophotographic carrier, the same measurements and tests as in Example 13 were performed. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

As a result, as in Example 13, the shaking test and the image forming test were good.

Example 15 Polyester resin obtained by condensing ethoxylated bisphenol-fumaric acid-trimellitic acid (monomer composition weight ratio = 50: 40: 10) 40% Magnetite (particle size: 0. 26 μm) 60% A spherical carrier core material was obtained in the same manner as in Example 14 except that the above materials were used. The particle size of this carrier core material was 54 μm.

The surface of the obtained carrier core material was coated with the following coating resin in the same manner as in Example 1. Styrene-phenyl acrylate copolymer (monomer composition weight ratio = 50: 50 weight average molecular weight (Mw) = 56,
000 Weight average molecular weight / number average molecular weight (Mw / M
n) = 4.5) -Vinylidene fluoride-tetrafluoroethylene copolymer (monomer composition weight ratio = 75: 25, weight average molecular weight (Mw) = 210,000) 50%

The carrier core material was coated with the above-mentioned resin material in the same manner as in Example 13 using a carrier coating solution having 10% dissolved in methyl ethyl ketone so that the coating resin amount was 1.2%, An electrophotographic carrier was obtained.
When the same measurement and test as in Example 13 were performed, good results were obtained as in Example 13. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

(Example 16) A carrier core material was produced in the same manner as in Example 15 except that the amount of magnetite in Example 15 was changed to 38% (the rest being polyester resin). The resin coating material used in Example 15 was dissolved in 10% in methyl ethyl ketone so that the coating resin amount was 1.2%, and the carrier core material was coated as a coating solution in the same manner as in Example 15. , A carrier for electrophotography was obtained. Using this electrophotographic carrier, measurements and tests were carried out in the same manner as in Example 13. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.
Shown in

The results of the shaking test were as good as those of Example 15, but in the image forming test under low humidity, some carrier adhesion was observed and the solid image density was slightly lower than that of Example 15. However, there was no particular problem in practice.

Example 17 Phenol 10.0% Formaldehyde 5.0% (Formaldehyde about 3%)
7%, about 10% methanol, the rest is water) Magnetite (particle size 0.25 μm) 85.0%

Ammonia using the above materials as a basic catalyst,
Using calcium fluoride as a polymerization stabilizer, while stirring in an aqueous phase, the temperature was gradually raised to 80 ° C. and polymerization was performed for 2 hours to obtain a carrier core material. The particle size of this carrier core material was 38 μm. The resin coating material used in Example 15 was coated on the obtained carrier core material in an amount of 1.1.
Coating was carried out in the same manner as in Example 15 using a methyl ethyl ketone solution in which the content of 10% was dissolved to obtain a carrier for electrophotography. When this electrophotographic carrier was used to perform the same measurements and tests as in Example 13, good results similar to Example 13 were obtained. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

(Comparative Example 12) The carrier core material prepared in Example 17 was used as an electrophotographic carrier without being coated with a resin coating material, and the same measurement and test as in Example 13 were carried out. In the test, desorption of the magnetic substance was observed. Further, in the image output test, the image was distorted, which was considered to be due to the decrease in the applied bias voltage. The physical properties of the carrier are shown in Table 5, and the evaluation results are shown in Table 6.

(Example 18) 100 parts of styrene-2-ethylhexyl acrylate-dimethylaminoethyl methacrylate copolymer (monomer composition weight ratio = 80: 15: 5). Copper phthalocyanine 4 parts ・ Low molecular weight polypropylene 5 parts

Using the above materials, cyan particles having a weight average diameter of 11.7 μm were obtained in the same manner as in Example 1. The cyan particles 10
0.8 parts of positively chargeable colloidal silica treated with amino-modified silicone oil was mixed with 0 part by a Henschel mixer to obtain a positively chargeable cyan toner.

The cyan toner and the electrophotographic carrier used in Example 17 were mixed so as to have a toner concentration of 8% to prepare a two-component developer, and a copying machine NP4 manufactured by Canon was used.
When the measurement and the test were carried out in the same manner as in Example 13 using 835, it was also excellent in the positive charging property in the image output test.
A uniform image was obtained. Table 6 shows the evaluation results.

[0300]

[Table 5]

[0301]

[Table 6]

Example 19 Styrene 25.0% 2-Ethylhexyl acrylate 8.3% Reduced iron powder (particle diameter 0.34 μm) 66.7%

The above materials are heated to a temperature of 70 ° C. in a container,
It was made to melt | dissolve and it was set as the monomer mixture. Further, while maintaining the temperature at 70 ° C., the initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was put into a 2 liter flask containing 1.2 liter of a 1% polyvinyl alcohol (PVA) aqueous solution, and was heated at 70 ° C. by a homogenizer to 450 ° C.
The composition was granulated by stirring at 0 rpm for 10 minutes. afterwards,
While stirring with a paddle stirrer, polymerization was carried out at 70 ° C. for 10 hours. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic substance-dispersed styrene acrylic slurry was washed and filtered. This was dried to obtain a carrier core material.

The surface of the obtained carrier core material was coated with the following resin coating material. Styrene-2-hydroxyethyl methacrylate-methyl methacrylate copolymer (monomer composition weight ratio = 37:
10:53, hydroxyl value (KOHmg / g) = 28
Weight average molecular weight (Mw) = 48,000 Weight average molecular weight / Number average molecular weight (Mw / Mn) = 3.4)

1 part of the quaternary ammonium salt shown in <Example 1> as particles was added to 100 parts of a mixed solution of 20% acetone and methyl ethyl ketone (mixing weight ratio = 1: 1) of the above styrene copolymer. The mixture was added and stirred with a stirrer until they were sufficiently mixed to prepare a carrier coating solution.

Next, this carrier coating solution was applied to the above carrier core material by means of a coating machine (manufactured by Okada Seiko Co., Ltd .: Spiracoater). The obtained carrier core material after coating was dried at a temperature of 90 ° C. for 1 hour to remove the solvent and obtain a carrier for electrophotography in which the surface of the carrier core material was coated with a resin coating material. Observation by an electron microscope confirmed that the carrier core material was uniformly coated with the resin. Table 7 shows the physical properties of the above carriers. -Polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 100 parts-Phthalocyanine pigment 5 parts-Chromium complex salt of di-tert-butylsalicylic acid 4 parts

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a three-roll mill three times, cooled, and then coarsely pulverized with a hammer mill to a particle size of about 1 to 2 mm. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain a negatively chargeable cyan powder (toner) having a weight average diameter of 8.8 μm.

[0308] 100 parts of the cyan powder and 0.5 part of silica fine powder hydrophobized with hexamethyldisilazane were mixed by a Henschel mixer to prepare a cyan toner having silica fine powder on the toner particle surface. did.

This cyan toner and the above electrophotographic carrier were mixed in temperature / humidity L / L (temperature 15 ° C./humidity 10% R
H), N / N (Temperature 23 ° C / Humidity 60% RH), H / H
After left in each environment of (temperature 30 ° C./humidity 90% RH) for 4 days, they were mixed at a toner concentration of 5%, and the charge amount was measured by the method of FIG. The above results show that, as shown in Table 10, the change in the charge amount due to the environmental change is small.

Next, the above electrophotographic carrier was mixed in the above cyan toner N / N environment at a toner concentration of 5% to prepare a two-component developer, and a full color leather copying machine CLC in which the development contrast was fixed at 350V. Using −500 (manufactured by Canon Inc.), 10,000 sheets were subjected to a copy durability test under the above various environments. From the above results, as shown in Table 10, it is understood that the durability is excellent and the change due to the environmental change is small.

Next, the cyan toner and the electrophotographic carrier are mixed in an environment of temperature / humidity of N / N (23 ° C./60% RH) so that the toner concentration is 5% to obtain a two-component developer. It was 100 g of the obtained two-component developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. After that, the two-component developer was taken out, and the developer was observed with an electron microscope. As a result, desorption of the magnetic material from the carrier, peeling of the coating material, and filming by the toner were not observed. No detachment or embedding of the external additive of the toner was observed.

A cyan toner and the above electrophotographic carrier were mixed in an environment of temperature / humidity of L / L (15 ° C./10% RH) so that the toner concentration was 8% to obtain a two-component developer.
Under the same environment, this was placed in a developing unit for Canon full-color laser copying machine CLC-500, and idling was performed for 30 minutes by driving an external motor (peripheral speed 300 rpm). After that, using CLC-500, a development contrast of 350
An image was displayed as V. As a result, the density of the solid image was sufficient and the reproducibility of the halftone portion was good.

Comparative Example 13 The carrier core material used in Example 19 was used as an electrophotographic carrier without resin coating, and the same measurements and tests as in Example 19 were performed. The physical properties of the carrier are shown in Table 7, and the evaluation results are shown in Tables 9 and 10.

As a result of the shaking test, desorption of the magnetic material from the carrier was observed by observation with an electron microscope.

Comparative Example 14 For the electrophotography, the resin coating material used in Example 19 was coated in the same manner as in Example 19 by using reduced iron particles of 45 μm in place of the carrier core material used in Example 19. After obtaining the carrier, the same measurement and test as in Example 19 were performed. The physical properties of the carrier are shown in Table 7, and the evaluation results are shown in Tables 9 and 10.

As a result of the shaking test, there was no change in the electrophotographic carrier before the shaking, but some embedding of the external additive on the toner surface was observed. As a result of the image display test, a certain amount of roughness was observed especially in the halftone portion.

Comparative Example 15 Styrene-methyl methacrylate copolymer (monomer composition weight ratio = 60: 40 weight average molecular weight (Mw) = 133
000 Weight average molecular weight / number average molecular weight (Mw / M
n) = 29)

A mixed solution 100 of 20% acetone and methyl ethyl ketone (mixing weight ratio = 1: 1) of the above resin material
Was applied to the same carrier core material as in Example 19 by the same method as in Example 19 to obtain an electrophotographic carrier in which the surface of the carrier core material was covered with a resin coating material. Table 7 shows the physical properties of this electrophotographic carrier. Using this electrophotographic carrier, the same measurements and tests as in Example 19 were performed. The evaluation results are shown in Tables 9 and 10.

Example 20 Using the same formulation as in Example 19, the temperature was raised to 70 ° C. in a container and the mixture was dissolved to obtain a monomer mixture. Further, while maintaining the temperature at 70 ° C., the initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was put into a 2 liter flask containing 1.2 liter of a 1% polyvinyl alcohol (PVA) aqueous solution, and the mixture was mixed with a homogenizer at 70 ° C. at 2500 rpm for 1 hour.
The composition was granulated by stirring for 0 minutes. Then, while stirring with a paddle stirrer, polymerization was performed at 70 ° C. for 10 hours. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic substance-dispersed styrene acrylic slurry was washed and filtered. This was dried to obtain a carrier core material. The particle size of the obtained carrier core material was 72 μm. The surface of this carrier core material was coated in the same manner as in Example 19 to obtain a carrier.
Table 7 shows the physical properties of this carrier. The same measurements and tests as in Example 19 were performed using the obtained carrier. The evaluation results are shown in Tables 9 and 10.

As a result of an image forming test after idling under a low humidity, a certain amount of roughness was observed especially in a halftone portion, but it was not a problem in practical use.

(Example 21) Styrene-2-ethylhexyl acrylate-butyl acrylate copolymer (monomer composition ratio = 80: 5: 1)
5) 50% ・ Reduced iron powder (0.36 μm) 50%

The above materials were thoroughly premixed with a Henschel mixer and then with a three roll mill to at least 2
The mixture was melt-kneaded more than once, cooled, and coarsely pulverized to a particle size of about 2 mm using a hammer mill. Then, it was finely pulverized to a particle size of about 49 μm by an air jet pulverizer. Further, the obtained finely pulverized product was mechanomill MM-10 (manufactured by Okada Seiko)
It was thrown into and mechanically spheroidized. The spheronized finely pulverized particles were further classified to obtain a carrier core material. The particle size of the obtained carrier core material was 48 μm.

The surface of the obtained carrier core material was coated with a resin coating material in the same manner as in Example 19 to obtain an electrophotographic carrier.

Table 7 shows the physical properties of this carrier. The obtained electrophotographic carrier was measured and tested in the same manner as in Example 19. The evaluation results are shown in Tables 9 and 10.

As a result, as in Example 19, the change in the charge amount due to the environmental change was small, and the results were good in the shaking test and the image forming test.

(Example 22) An electrophotographic carrier similar to that used in Example 21 was manufactured by NP-5 manufactured by Canon Inc.
000 Copier toner (containing 100 parts of styrene copolymer and paraffins as binder resin, 9 parts of carbon black as colorant, 3 parts of negatively chargeable metal-containing complex as charge control agent) and toner concentration 4 % / Temperature / humidity is L / L
(15 ° C / 10% RH), N / N (23 ° C / 60% R
H) and H / H (30 ° C./90% RH) were mixed under each environment, and the charge amount was measured by the method of FIG. As a result, the toner charge amount was almost constant regardless of the environment. N above
/ N environment using a two-component developer produced in Canon Inc. Copier NP-5000 modified machine (θ ₁ : 16 °,
d: 800 μm, e: 500 μm, AC electric field: 2000
Hz-2000Vpp, DC electric field: 550V),
An image drawing test was conducted under the above various environments. The results are shown in Table 1.
As shown in 0, it is found that the durability is excellent and there is little change due to environmental changes. Further, during the above-described image output test, carrier adhesion on the photosensitive drum or paper was extremely small. In addition, a polybin shaking test using a Turbula mixer was performed in the same manner as in Example 19. Table 9 shows the results.

Example 23 Polyester resin obtained by condensing ethoxylated bisphenol-fumaric acid-trimellitic acid (50/40/10) 40% Magnetite (particle diameter 0.26 μm) 60%

Using the same materials as in Example 21, a spherical carrier core material was obtained. The particle size of this carrier core material was 53 μm.

The obtained carrier core material was coated with the following resin coating material. -Styrene-methyl methacrylate-2-ethylhexyl acrylate copolymer (monomer composition weight ratio = 45: 3)
5:20 weight average molecular weight (Mw) = 41,000 weight average molecular weight / number average molecular weight (Mw / Mn) = 2.5)

To 100 parts of a 10% methyl ethyl ketone solution of the above material, 0.75 part of the quaternary ammonium salt shown in <Example 12> as particles was added, and the mixture was stirred with a stirrer until sufficiently mixed to form a carrier coating solution. It was made.

This carrier coating solution was applied to the carrier core material by a coating machine (Okada Seiko Co., Ltd .: Spiracoater). The obtained carrier after coating was heated at 60 ° C. for 3 hours to obtain an electrophotographic carrier in which the surface of the carrier core material was coated with the resin coating material. Table 7 shows the physical properties of the obtained carrier. When the same measurement and test as in Example 19 were performed, good results were obtained as in Example 19.
The evaluation results are shown in Tables 9 and 10.

(Example 24) A carrier core material was prepared in the same manner as in Example 22 except that the amount of magnetite in Example 23 was changed to 38% (the rest being polyester resin). This was coated with the resin coating material used in Example 23 in the same manner as in Example 23 to obtain an electrophotographic carrier. Table 7 shows the physical properties of this carrier. The carrier obtained is used in Example 19.
Measurements and tests were performed in the same manner as in. The result of the shaking test was as good as that of Example 23, but some carrier adhesion was observed on the photosensitive drum, and the density of the solid image was the same as that of Example 23 in the image forming test under low humidity. It was a little lower than that, but it was not a problem in practice. The evaluation results are shown in Tables 9 and 10.

Example 25 Phenol 13.5% Formaldehyde (formaldehyde about 37%, methanol about 10%, balance water) 6.0% Magnetite (particle size 0.25 μm) 80.5%

Ammonia using the above materials as a basic catalyst,
Using calcium fluoride as a polymerization stabilizer, the mixture was stirred in an aqueous phase, gradually heated to a temperature of 80 ° C., and polymerized for 2 hours. The particle size of the obtained carrier core material is 41
μm. The carrier core material was coated in the same manner as in Example 23 using a methyl ethyl ketone solution in which 10 wt% of the coating resin used in Example 23 was dissolved. Table 7 shows the physical properties of the obtained electrophotographic carrier. When this electrophotographic carrier was used to perform the same measurements and tests as in Example 19, the same good results as in Example 19 were obtained.

Comparative Example 16 The carrier core material prepared in Example 25 was used as an electrophotographic carrier without coating. Table 7 shows the physical properties of this electrophotographic carrier.
When a test similar to that of Example 19 was performed, desorption of the magnetic material was observed in the shaking test. Further, in the image output test, the image was distorted, which was considered to be due to the decrease in the applied bias voltage. The evaluation results are shown in Tables 9 and 10.

(Example 26) -Styrene-2-ethylhexyl acrylate-dimethylaminoethyl methacrylate copolymer (monomer composition weight ratio = 80/15/5) 100 parts-copper phthalocyanine 4 parts-low molecular weight polypropylene 5 parts

Using the above materials, blue particles having a weight average particle diameter of 11.7 μm were obtained in the same manner as in Example 19. 0.8 parts of positively charged colloidal silica treated with amino-modified silicone oil was mixed with 100 parts of the particles by a Henschel mixer to obtain a positively charged cyan toner.

The charge amount of the toner in each environment was measured in the same manner as in Example 19 except that the toner density was set to 8% using the above toner and the electrophotographic carrier used in Example 25. As shown in Table 10, the above results show that there is little change in the environment.

Next, the toner and the electrophotographic carrier used in Example 25 were adjusted to N / N so that the toner concentration was 8%.
A two-component type developer was prepared by mixing below, and a copying durability test was carried out under various environments using a Canon copying machine NP-4835. An image with stable and good image density was obtained.

Next, the toner and the electrophotographic carrier used in Example 25 were mixed at a temperature / humidity of N / N (23 ° C./60).
% RH) and mixed so as to have a toner concentration of 5% to obtain a two-component developer. 100 g of the obtained two-component developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. After that, the two-component developer was taken out, and the two-component developer was observed with an electron microscope. As a result, detachment of the magnetic substance from the carrier, peeling of the coating agent,
No filming due to toner was observed. No detachment or embedding of the external additive of the toner was observed.

Next, the toner and the electrophotographic carrier used in Example 25 were mixed at a temperature / humidity of L / L (15 ° C./10
% RH) environment and a toner concentration of 8% was mixed to obtain a two-component developer. Under the same environment, this was placed in a color developing device of a Canon copying machine NP-4835, and idling was performed for 30 minutes by driving an external motor. After this, NP-483
Image output was performed using No. 5. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was good. The evaluation results are shown in Tables 9 and 10.

(Comparative Example 17) Styrene-methyl methacrylate copolymer (monomer composition weight ratio = 60: 40, weight average molecular weight (Mw) = 13)
3,000 weight average molecular weight / number average molecular weight (Mw /
Mn) = 29) To 100 parts of a 20% methyl ethyl ketone solution of the styrene-based copolymer, 1 part of a quaternary ammonium salt represented by the following formula as particles was added, and a carrier coating solution was prepared in the same manner as in Example 19. Was produced. In the stirring and mixing step, the quaternary ammonium salt was difficult to mix uniformly as in Example 19, and was poorly compatible with the resin.

[0343]

[Outside 23]

This carrier coating solution was coated on the carrier core material used in Example 19 in the same manner as in Example 19 to obtain an electrophotographic carrier in which the surface of the carrier core material was coated with a resin coating material. Using this electrophotographic carrier, the same copy durability test as in Example 19 was conducted. The evaluation results are shown in Tables 9 and 10.

Comparative Example 18 The quaternary ammonium salt used in Comparative Example 17 was dissolved in distilled water to prepare a 0.5% adjustment solution. Ferrite particles having an average particle size of 45 μm were immersed as a carrier core material in this adjustment liquid, stirred for 20 minutes, filtered, and dried at 105 ° C. for 2 hours to obtain an electrophotographic carrier. Table 8 shows the physical properties of the carrier. Using the obtained electrophotographic carrier, the same toner as in Example 19 was used, and the same evaluation as in Example 19 was performed. As a result, as shown in Table 10, the amount of charge was almost the same in each environment, but the image density difference due to the environmental change became large by the copy durability test. After the shaking test with the Turbula mixer, the carrier surface was observed with an electron microscope. As shown in Table 9, toner filming was recognized.

Example 27 Styrene-2-hydroxyethyl methacrylate-methyl methacrylate copolymer (monomer composition weight ratio = 35:
8:57, hydroxyl value (KOHmg / g) = 30
Weight average molecular weight (Mw) = 52,000 weight average molecular weight / number average molecular weight (Mw / Mn) = 2.5) 5 parts-vinylidene fluoride-tetrafluoroethylene copolymer (monomer composition weight ratio = 75: 25 weight) Average molecular weight (Mw) = 210,000) 5 parts

The above resin material (total 10 parts) was mixed with acetone and methyl ethyl ketone in a mixed solvent (mixed weight ratio = 1: 1).
It was dissolved in 90 parts to prepare a 10% concentration preparation solution. Further, to 100 parts of this solution, 0.5 part of the quaternary ammonium salt of <Example 12> as particles was added, and stirred with a stirrer until sufficiently mixed to prepare a carrier coating solution.

This carrier coating solution was applied to the carrier core material used in Example 25 in the same manner as in Example 25, using an applicator (supplied by Okada Seiko Co., Ltd.). The obtained coated carrier was dried at 40 ° C. for 1 hour to remove the solvent, and then heated at 110 ° C. for 1 hour to obtain an electrophotographic carrier in which the surface of the carrier core material was coated with the resin coating material.
When the obtained carrier was observed with an electron microscope,
It was confirmed that the carrier core material was uniformly coated with the coating resin. Table 8 shows the physical properties of the carrier. -Styrene-2-ethylhexyl acrylate-dimethylaminoethyl methacrylate copolymer (monomer composition weight ratio = 80: 15: 5) 10 parts-Copper phthalocyanine pigment 4 parts-Low molecular weight polypropylene 6 parts

The above compositions were mixed, melt-kneaded, pulverized and classified to produce cyan resin fine particles having a weight average particle diameter of 11 μm. Cyan toner was prepared by mixing 100 parts of cyan resin fine particles and 0.8% of positively charged hydrophobic colloidal silica treated with amino-modified silicone oil with a Henschel mixer.

Using the above electrophotographic carrier and the above toner, the toner concentration was 8% and the temperature / humidity was L / L (15 ° C./10% R).
H), N / N (23 ° C / 60% RH), H / H (30 ° C
/ 90% RH) and mixed in each environment, and the charge amount was measured by the method of FIG. As shown in Table 10, the results show that the influence of environmental changes is extremely small. N manufactured by Canon Inc. using a two-component developer prepared under N / N environment
An image output durability test was conducted in each of the above environments with a P-4835 blue developing device.

As shown in Table 10, the initial reflection image density was sufficiently high irrespective of environmental changes, and the reflection image density was sufficiently high even after 10,000 sheets of durability, and a good image free from fogging and scattering was obtained. Was given. The carrier was recovered from the two-component type developer after 10,000 sheets of durability and observed with an electron microscope.
As shown in (1), no remarkable spent formation by toner and deterioration such as peeling of the coated resin coating layer were observed.

Further, during the series of image forming tests, the carrier adhesion on the electrostatic image carrier or the paper was extremely small.

Example 28 Styrene-2-ethylhexyl methacrylate-butyl methacrylate copolymer (monomer composition polymerization ratio = 40: 1)
0:50 Weight average molecular weight (Mw) = 45,000 Weight average molecular weight / Number average molecular weight (Mw / Mn) = 2.
8)

A 1.0% ethanol solution of a quaternary ammonium salt (solubility 1.0 g / 100 g (solubility 1.0 g / 100 g (100 g of a 20% methyl ethyl ketone solution of the above resin material and a quaternary ammonium salt shown in <Example 8>)) 20 parts of ethanol) and above) were stirred with a stirrer until they were sufficiently mixed to prepare a carrier coating solution.

This carrier coating solution was applied to a carrier core material similar to that used in Example 25 in the same manner as in Example 25, using a coating machine (Spira coater, Okada Seiko Co., Ltd.). The obtained carrier after coating was dried at 60 ° C. for 3 hours to remove the solvent and obtain a carrier for electrophotography in which the surface of the carrier core material was coated with a resin coating material. Table 8 shows the physical properties of the carrier.

This electrophotographic carrier and a toner for Canon copier NP-5000 (binder resin: styrene copolymer, paraffins; 100 parts, colorant: carbon black; 9 parts, charge control agent: negative charge) Metal-containing complex; 3 parts)
And temperature / humidity are L / L (15 ° C / 10%), N / N
Under each environment of (23 ° C./60%) and H / H (30 ° C./90%), the toner concentration was mixed to 2%, and the charge amount was measured by the method of FIG.

Using the two-component type developer produced under the above N / N environment, Canon Co., Ltd. copying machine NP-5000 remodeling machine (θ ₁ : 16 °, d: 800 μm, e: 500 μm,
AC electric field: 2000 Hz-2000 V, DC electric field: 55
0V), an image output durability test was performed under each of the above environments.

As a result, the reflection image density is H / H: 1.
31, N / N: 1.33, L / L: 1.34, which is sufficiently high, and H / H: 1.29, N / N: 1.3 even after 10,000 sheets of durability.
2, L / L was as high as 1.31, and good images were obtained with little change due to environmental changes. Table 10 shows the evaluation results.

When the developer was collected after running 10,000 sheets and the carrier was observed with an electron microscope, no noticeable deterioration of toner such as spent and peeling of the resin coating layer was observed. A polybin shaking test using a Turbula mixer was conducted in the same manner as in Example 19. Table 9 shows the results.

During a series of image output tests, carrier adhesion on the electrostatic image carrier or paper was extremely low.

[0361]

[0362]

[0363]

[Table 7]

[0364]

[Table 8]

[0365]

[Table 9]

[0366]

[Table 10]

Example 29 100 parts of polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 5 parts of phthalocyanine pigment 4 parts of chromium complex salt of di-tert-butylsalicylic acid

The above formulation amounts were sufficiently premixed with a Henschel mixer and at least 2 by a three roll mill.
Melt and knead more than once, after cooling and coarse pulverization with a cutter mill, fine pulverization using a fine pulverizer using a jet stream,
The obtained finely pulverized powder was classified by a fixed wall type air classifier to produce a classified powder. Furthermore, the obtained finely divided powder was subjected to strict classification at the same time by using a multi-division classifier utilizing the Coanda effect (Elbow Jet classifier manufactured by Nittetsu Mining Co., Ltd.) to precisely remove ultrafine powder and coarse powder at a weight average particle size of 7.6 μm. A cyan powder (toner) was obtained. Table 11 shows the particle size distribution of this toner.

100 parts of the above-mentioned cyan toner and 0.5 part of silica fine powder hydrophobized with hexamethyldisilazane were mixed by a Henschel mixer to prepare a cyan toner having silica fine powder on the toner particle surface.

Example 19 Example 19 is repeated except that the cyan toner obtained as described above is used instead of the toner used in Example 19.
When a test was conducted in the same manner as in Example 19, the same results as in Example 19 were obtained, and in particular, the resolution and the toner consumption amount were superior to those in Example 19.

[0371]

[Table 11]

[0372]

The electrophotographic carrier of the present invention comprises a carrier core material and a resin coating material for coating the surface of the carrier core material, and the carrier core material is dispersed in the binder resin and the binder resin. (1) Spent resistance (2) Impact resistance (prevention of carrier breakage) (3) Toner, since the resin coating material contains the above-mentioned specific substances. Prevention of deterioration (4) Developability (5) Prevention of carrier adhesion on the photoconductor (6) Control of carrier resistance (7) Stabilization of toner chargeability can be fully satisfied and high-quality images can be obtained for a long period of time. It can be provided in a stable manner over the entire period.

Since the two-component type developer for developing an electrostatic image of the present invention contains the carrier having the above constitution as a carrier, it has the following effects.

(1) Since carrier deterioration such as toner spent due to durability is small, a good image can be formed for a long period of time.

(2) An image having a stable image density can be obtained with a very small change in charge amount due to environmental changes.

Even if the effects of (3) and (2) are durable, the effects cannot be damaged.

In the method for producing a carrier for electrophotography of the present invention, a coating solution or a coating dispersion containing the above specific coating material is applied to a carrier core material to coat the surface of the carrier core material with a resin coating material. Therefore, an electrophotographic carrier in which the coating material is uniformly dispersed in the resin coating material coated can be obtained.

In the image forming method of the present invention, the latent image is developed by applying the bias voltage in the developing region by using the two-component type developer having the above-mentioned constitution. Therefore, current leakage or carrier electrostatic charge image bearing member is carried out. It is possible to reduce the adhesion of the on the surface of, and to form a good image for a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic view schematically showing an electric resistance measuring device.

FIG. 2 is an explanatory diagram showing an example of a developing device used in the image forming method of the present invention.

FIG. 3 is a schematic view schematically showing an apparatus for measuring the triboelectric charge of toner of the two-component developer of the present invention.

[Explanation of symbols]

 1 Main Electrode 2 Upper Electrode 3 Insulator 4 Ammeter 5 Voltmeter 6 Constant Voltage Device 7 Carrier 8 Guide Ring 11 Latent Image Carrier 22 Development Carrier (Development Sleeve) 23 Permanent Magnet 24 Developer Control Member (Nonmagnetic Blade) 26 Magnetic Carrier Limiting Member 27 Magnetic Carrier 30 Scattering Prevention Electrode Plate 36 Developing Container 37 Toner 40 Sealing Member 60 Toner Supply Roller 61 Screw 62 Screw 63 Limit Plate 64 Conveying Screw 71 Conductive Screen 72 Measuring Container 73 Lid 74 Suction Machine 75 Suction Port 76 Air flow control valve 77 Vacuum gauge 78 Electrometer 79 Condenser

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yasuko Amano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatsuya Tada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (56) Reference JP-A-2-29665 (JP, A) JP-A-3-27054 (JP, A) JP-A-63-2078 (JP, A) JP-A-2-157854 (JP, A) A) JP-A-63-235958 (JP, A) JP-A-64-40953 (JP, A) JP-A-2-288848 (JP, A) JP-A-2-240665 (JP, A) JP-A-63 -113554 (JP, A) JP 62-5257 (JP, A) JP 62-70864 (JP, A)

Claims (25)

(57) [Claims] 1. A carrier for electrophotography comprising a carrier core material and a resin coating material for coating the surface of the carrier core material, wherein the carrier core material is a binder resin and a magnetic material dispersed in the binder resin. The resin coating material has body particles,
(A) a vinyl-based copolymer having a hydroxyl value of 1 to 100 (KOHmg / g), and (b) 30 to 90
Monomer ratio of the weight percent of the acrylic component, a styrene having a weight average molecular weight of 30000 to 70000 (Mw) and 2 to 10 weight-average molecular weight / number average molecular weight (Mw / Mn) - acrylic copolymer or Ranaru Group An electrophotographic carrier containing at least one member selected. 2. The resin coating material is 1 to 100 (KOH
The electrophotographic carrier according to claim 1, further comprising a vinyl-based copolymer having a hydroxyl value of mg / g). 3. The resin coating material is 1 to 100 (KOH
The electrophotographic carrier according to claim 1, which contains a vinyl-based copolymer having a hydroxyl value of mg / g) and a fluororesin. 4. The resin coating material comprises a molar ratio of acrylic component of 30 to 90% by weight, a weight average molecular weight (Mw) of 30,000 to 70,000 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10. Styrene with
The electrophotographic carrier according to claim 1, further comprising an acrylic copolymer. 5. The resin coating material comprises a molar ratio of an acrylic component of 30 to 90% by weight, a weight average molecular weight (Mw) of 30,000 to 70,000 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10. Styrene with
The carrier for electrophotography according to claim 1, which contains an acrylic copolymer and a fluorine-containing resin. 6. The carrier for electrophotography has a true specific gravity of 1.5.
To claims 1 to 5 electrophotographic carrier it is according and having a 5.0. 7. The magnetic fine particles may, claims 1 to 5 electrophotographic carrier according to characterized in that it has a under 60 emu / g or more magnetic force of the magnetic field 10K oersted. 8. The career is, 10 [mu] m to 60μm of
It claims 1 to 5 electrophotographic carrier according and having an average particle size. 9. The electrophotographic carrier is 10 ⁷ Ω · c.
m to claims 1 to 5 electrophotographic carrier according and having a specific resistance of 10 ¹⁴ Ω · cm. 10. The carrier core material is produced by a polymerization method, according to any one of claims 1 to 5.
The described electrophotographic carrier. 11. A two-component developer having a toner, a carrier core material, and a carrier having a resin coating material for coating the surface of the carrier core material, wherein the carrier core material is a binder resin and the binder resin. The resin coating material has magnetic fine particles dispersed therein.
Vinyl-based copolymer having a hydroxyl value of (KOHmg / g), and (b) monomer ratio of acrylic component of 30 to 90% by weight, weight average molecular weight (Mw) of 30,000 to 70,000 and weight average molecular weight of 2 to 10 / number average molecular weight (Mw / Mn) styrene having - two-component developer which is characterized in that it contains at least one member selected from an acrylic copolymer or Ranaru group. 12. The resin coating material is 1 to 100 (KO
The two-component developer according to claim 11, which contains a vinyl-based copolymer having a hydroxyl value of Hmg / g). 13. The resin coating material is 1 to 100 (KO
The two-component developer according to claim 11, which contains a vinyl-based copolymer having a hydroxyl value of Hmg / g) and a fluorine-containing resin. 14. The resin coating material is 30 to 90% by weight.
Molar ratio of acrylic component of 30,000 to 70,000
12. The two-component composition according to claim 11, which contains a styrene-acrylic copolymer having a weight average molecular weight (Mw) of 2 to 10 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10. Developer. 15. The resin coating material is 30 to 90% by weight.
Molar ratio of acrylic component of 30,000 to 70,000
The weight average molecular weight of (Mw) and 2 to styrene having a weight average molecular weight / number average molecular weight of 10 (Mw / Mn) - claim 11, characterized by containing an acrylic copolymer and a fluorine-containing resin The two-component developer described. 16. A coating solution or coating dispersion in which a resin coating material is dissolved or dispersed is prepared, the surface of the carrier core material is coated with the prepared coating solution or coating dispersion, and the coated carrier core material is In the method for producing an electrophotographic carrier for obtaining a carrier by drying, the carrier core material has a binder resin and magnetic fine particles dispersed in the binder resin, and the resin coating material is
(A) a vinyl-based copolymer having a hydroxyl value of 1 to 100 (KOHmg / g), and (b) 30 to 90
Monomer ratio of the weight percent of the acrylic component, a styrene having a weight average molecular weight of 30000 to 70000 (Mw) and 2 to 10 weight-average molecular weight / number average molecular weight (Mw / Mn) - acrylic copolymer or Ranaru Group A method for producing a carrier for electrophotography, comprising at least one member selected. 17. The resin coating material is 1 to 100 (KO
The method for producing a carrier for electrophotography according to claim 16, further comprising a vinyl-based copolymer having a hydroxyl value of Hmg / g). 18. The resin coating material is 1 to 100 (KO
The method for producing an electrophotographic carrier according to claim 16, which comprises a vinyl-based copolymer having a hydroxyl value of Hmg / g) and a fluororesin. 19. The resin coating material is 30 to 90% by weight.
Molar ratio of acrylic component of 30,000 to 70,000
The electrophotography according to claim 16, which contains a styrene-acrylic copolymer having a weight average molecular weight (Mw) of 2 to 10 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10. Of manufacturing carrier for car. 20. The resin coating material is 30 to 90% by weight.
Molar ratio of acrylic component of 30,000 to 70,000
The weight average molecular weight of (Mw) and 2 to styrene having a weight average molecular weight / number average molecular weight of 10 (Mw / Mn) - claim 16, characterized by containing an acrylic copolymer and a fluorine-containing resin A method for manufacturing the described electrophotographic carrier. 21. An image forming method for developing a latent image formed on an electrostatic charge image bearing member by applying a bias voltage in a developing area and using a two-component developer having a toner and a carrier, wherein the carrier core material comprises: The binder resin and the magnetic fine particles dispersed in the binder resin, the resin coating material,
(A) a vinyl-based copolymer having a hydroxyl value of 1 to 100 (KOHmg / g), and (b) 30 to 90
Monomer ratio of the weight percent of the acrylic component, a styrene having a weight average molecular weight of 30000 to 70000 (Mw) and 2 to 10 weight-average molecular weight / number average molecular weight (Mw / Mn) - acrylic copolymer or Ranaru Group An image forming method comprising at least one member selected. 22. The resin coating material is 1 to 100 (KO
22. The image forming method according to claim 21, further comprising a vinyl-based copolymer having a hydroxyl value of Hmg / g). 23. The resin coating material is 1 to 100 (KO
22. The image forming method according to claim 21, further comprising a vinyl-based copolymer having a hydroxyl value of Hmg / g) and a fluororesin. 24. The resin coating material is 30 to 90% by weight.
Molar ratio of acrylic component of 30,000 to 70,000
22. The image forming method according to claim 21, further comprising a styrene-acrylic copolymer having a weight average molecular weight (Mw) of 2 to 10 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10. Method. 25. The resin coating material is 30 to 90% by weight.
Molar ratio of acrylic component of 30,000 to 70,000
22. A styrene-acrylic copolymer having a weight average molecular weight (Mw) of 2 to 10 and a weight average molecular weight / number average molecular weight (Mw / Mn) of 2 to 10 and a fluororesin are contained. The image forming method described.