JP3062964B2 - Magnetic dispersion carrier, two-component developer for electrostatic image development, method for producing magnetic dispersion carrier, 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 a magnetic material-dispersed carrier and a method for producing the same. The present invention also relates to a two-component developer for developing an electrostatic image having a toner and a carrier. Further, the present invention relates to an image forming method for developing a latent image with a two-component developer having a toner and a carrier by applying a bias voltage in a developing area.

[0002]

2. Description of the Related Art Generally, in an electrostatic recording apparatus using electrophotography, selenium, OPC (organic photoconductor), α-S
Using a photoconductive material such as i as a photoreceptor, the photoreceptor is uniformly charged by various means, and then illuminated with a light image on the photoreceptor surface to form an electric latent image corresponding to the light image. In general, a method is used in which a latent image is formed on the surface of a photoreceptor, toner is adhered to the latent image using a magnetic brush developing method or the like, and the latent image is visualized.

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

[0004] The developer having the toner and the carrier is
A developing layer containing a magnet is coated to a predetermined layer thickness by a developer layer thickness regulating member, and is conveyed to a developing area formed between the photoreceptor and the developing sleeve by using a magnetic force. You.

A predetermined developing bias voltage is applied between the photosensitive member and the developing sleeve, and the toner is developed on the photosensitive member in the developing area.

There are various characteristics required for the above-mentioned carrier, but particularly important characteristics are appropriate charging properties, pressure resistance to an applied electric field, impact resistance, abrasion resistance, abrasion resistance, spent resistance, developability, and productivity. And the like.

For example, when a developer is used for a long time,
Toner filming occurs in which toner, which does not contribute to development, which is called spent toner, is fused to the surface of the carrier, and as a result, the developer deteriorates and the image quality of a developed image deteriorates.

In general, (1) If the true specific gravity of the carrier is too large, the load on the developer becomes large when the developer is made to have a predetermined layer thickness on the sleeve by the developer layer thickness regulating member. In the long-term use of the developer, (a) the toner filming described above, (b) carrier destruction, and (c) deterioration of the toner are likely to occur. As a result, the deterioration of the developer and the image quality of the developed image are caused. It will be easier. (2) When the particle size of the carrier increases, the load on the developer increases as in (1) above.
To (c) tend to occur, and as a result, the developer tends to deteriorate. It is also well known that (d) poor reproducibility of a developed image on fine lines, that is, poor developability.

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

In addition, it is necessary to address the problem of the developing property (d) by reducing the particle size of the carrier.

To solve the above-mentioned problems (a) to (d), a carrier having a small particle size in which magnetic particles are dispersed in a binder resin, for example, by a pulverization method disclosed in JP-A-54-66134. It is also possible to cope with this problem by using a magnetic material-dispersed small particle size carrier.

It is also possible to cope with this problem by using a magnetic material-dispersed small particle size carrier by a polymerization method disclosed in JP-A-61-9659.

However, when the magnetic substance-dispersed small particle size carrier does not contain a large amount of magnetic substance in the carrier particles, the saturation magnetization is small with respect to the particle diameter, and (e) the photoreceptor There is a problem that carrier adhesion occurs on the upper surface, and a mechanism for replenishing the developer or collecting the adhered carrier must be provided in the image forming apparatus. Has the disadvantage that it cannot be done.

Further, in the above-mentioned magnetic substance-dispersed small particle size carrier, when the magnetic substance is contained in a large amount, the impact resistance becomes weak because the amount of the magnetic substance increases with respect to the binder resin. 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 easily dropped from the carrier, and as a result, the developer is easily deteriorated. However, this method has a drawback that it cannot be a drastic measure for extending the life of the developer.

Further, in the above-mentioned magnetic substance dispersed small particle size carrier, when the magnetic substance is contained in a large amount, the specific resistance of the carrier decreases because the amount of the magnetic substance having a low specific resistance increases, and as a result, (F) There is also a disadvantage that image defects due to the leakage of the bias voltage applied during development are likely to occur.

Accordingly, even the above-mentioned magnetic substance-increasing magnetic substance-dispersed small particle size carrier has a drawback that it cannot be drastic as a measure for improving the developing property and extending the life of the developer. I have.

To cope with this, it is also possible to cope with the technique disclosed in Japanese Patent Application Laid-Open No. 58-21750, which covers the carrier with a resin. According to the carrier coated with the above resin, spent resistance, impact resistance, and pressure resistance against applied voltage can be improved.
In addition, since the charging characteristics of the toner can be controlled by the charging characteristics of the resin to be coated, a desired charge can be imparted to the toner by selecting the resin to be coated.

However, even in the above resin-coated carrier, when the amount of the coating resin is large and the specific resistance of the carrier is high, the charge amount of the toner in a low humidity environment increases.
So-called toner charge-up phenomenon easily occurs,
Further, when the amount of the coating resin is small, the specific resistance of the carrier becomes too low, so that there is a problem that it is difficult to control the coating amount such that an image defect is likely to occur due to leakage of the developing bias voltage.

Further, depending on the coating resin, even if the specific resistance of the carrier coated with the resin is considered to be an appropriate specific resistance in measurement, an image defect is likely to occur due to a leakage of a developing bias voltage, or in a low humidity environment. In some cases, the charge-up phenomenon easily occurs, and the carrier coated with the above resin also has a problem that it is difficult to control the carrier in consideration of developability.

Further, even in the case where the leakage of the developing bias voltage is prevented, in the above-mentioned conventional resin-coated carrier, the charge amount of the toner decreases due to the environmental change from a low temperature and low humidity environment to a high temperature and high humidity environment. It is difficult to control the fluctuation range of the toner within an appropriate range, and it is difficult to achieve both the prevention of toner scattering and fogging due to a decrease in the charge amount in a high humidity environment and the prevention of a low image density by charge-up in a low humidity environment. There was a problem.

In particular, in recent years, the toner particle size has tended to be reduced from the standpoint of improving image quality, and therefore, the variation in the amount of charge of the toner due to changes in the temperature and humidity of the environment tends to be even greater. There is a problem that it is more difficult to achieve both the prevention of toner scattering and fogging due to a decrease in the amount of charge in a humid environment and the prevention of low image density by charge-up in a low humid environment.

[0022]

As described above, in consideration of the above-mentioned required characteristics of the carrier, the conventionally used carrier still has a problem to be improved, and a satisfactory carrier has not been known so far. Not.

In particular, in a magnetic material-dispersed carrier in which magnetic particles are dispersed in a binder resin and the surface of which is coated with the resin, (1) Spent resistance (2) Impact resistance (prevention of carrier destruction) (3) Prevention of toner deterioration (4) Developability (5) Prevention of carrier adhesion on photoreceptor (6) Control of carrier resistance (7) Stability of toner charging during running and humidity fluctuation So far, nothing satisfactory is known.

Accordingly, the main object of the present invention is to solve the above-mentioned problems of the magnetic material dispersed type carrier whose surface is coated with the resin, and as a result, it is not necessary to replenish the carrier during running. Another object of the present invention is to provide a novel magnetic brush developing carrier which is excellent in developability and developer life by stabilizing the chargeability of the toner during running and humidity fluctuation.

More specifically, in a magnetic material-dispersed carrier in which the surface of a core material containing magnetic particles and a binder resin as described above is coated with a resin, the carrier has an impact resistance, a resistance value, and a charge application to toner. It is an object of the present invention to provide a novel magnetic brush developing carrier having improved stability and characteristics of a resin to be coated and having excellent developability and developer life.

Another object of the present invention is to provide a method for manufacturing a magnetic material-dispersed carrier which can solve the above-mentioned problems.

Another object of the present invention is to provide an image forming method in which current leakage or carrier adhesion to a photosensitive member is small when a latent image is developed by applying a bias voltage to a developing area.

[0028]

The present invention has a core material in which magnetic fine particles are dispersed in a binder resin,
A magnetic material-dispersed carrier obtained by coating the surface of the core material with a resin, wherein the resin coating the surface of the core material has a crosslinked alkoxyalkylated polyamide resin. .

Further, the present invention is a two-component developer for developing an electrostatic charge image, comprising the above-mentioned magnetic substance dispersed carrier and toner.

Further, the present invention provides a method of coating a carrier coating solution containing a resin material on a core material obtained by dispersing magnetic fine particles in a binder resin and drying the core material with a resin to coat the surface of the core material with the resin. In the method for producing a body-dispersed carrier, the carrier coating solution is a method for producing a magnetic substance-dispersed carrier having the above-mentioned coated resin material and a solvent for dispersing or dissolving the resin material.

Another object of the present invention is to provide a powder having a weight average particle size of 10 μm.
An object of the present invention is to provide a two-component developer for developing an electrostatic image with small environmental fluctuation even when a toner having a small particle diameter of m or less is used.

Further, according to the present invention, a latent image formed on a photoreceptor is developed by applying a bias voltage in a developing region by using a two-component developer for developing an electrostatic image having the magnetic substance-dispersed carrier and toner. Image forming method.

The present inventors have found that the use of the magnetic material-dispersed carrier having the above-described structure improves the impact resistance, the specific resistance, and the stability of charging the toner to the magnetic material-dispersed carrier. In addition, the inventors have found that the magnetic substance-dispersed carrier has excellent developability and developer life, thereby completing the present invention.

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

In general, polyamide resins represented by 6 nylon and the like have high abrasion resistance and elasticity, and have been considered as good carrier coating resins. However, they are hardly soluble in common organic solvents. In general, coating with a resin solution by a spray method using a fluidized bed or the like has a drawback as a carrier coating resin.

In the present invention, in order to improve this, an amide bond on the main chain of nylon is prepared by using nylon as a raw material.
After replacing the hydrogen atom of NHCO- with an alkoxyalkyl group to make it soluble in alcohol, etc., it has a crosslinked structure inside the molecule using a catalyst such as an acid to improve the mechanical strength. Is used as a carrier coating resin.

As a further significant feature, the resistance of the resin can be controlled by this alkoxyalkylation. That is, conventional nylon such as 6 nylon, its specific resistance is very high and 10 ¹⁴ Ω · cm or more, but remains the as previously described resulting in too high resistance, the resistivity by alkoxyalkylated according to the invention From 10 ⁸ to 10 ¹³
It can be controlled to Ω · cm.

Further, by providing the resin with a crosslinked structure, it is possible to remarkably improve various properties such as abrasion resistance, mechanical strength, moisture absorption resistance, and chargeability.

The carrier of the present invention can be obtained by forming a coating layer having an alkoxyalkylated polyamide resin obtained by crosslinking a carrier core material. As a step of obtaining the present resin-coated carrier, first, in a polyamide resin to be a base, a functional group in a main chain thereof is alkoxyalkylated by a substitution reaction. Next, this resin is applied to a carrier, and after the coating film is formed, crosslinking is carried out using an arbitrarily selected acid as a catalyst.

The effect of the crosslinked structure in the present invention is as follows. Crosslinking results in a three-dimensional complex three-dimensional network structure. Therefore, it can be said that the carrier has a desirable form as a carrier coating material whose mechanical properties such as abrasion resistance and impact resistance are required as its important characteristics. Uncrosslinked polyamide resin has a slight tack, and when coated on a carrier, the fluidity of the carrier is slightly reduced, but the surface is hardened by forming a crosslinked body, the frictional resistance between the carriers is reduced, and the fluidity is reduced. improves. In addition, by forming a crosslinked product, the water resistance is also improved.

The alkoxyalkylated polyamide resin used in the present invention is obtained by substituting the hydrogen atom of amide -NHCO- in the resin with an alkoxyalkyl group.
The alkoxyalkyl group has the following structure.

[0042]

Embedded image R ₁ is preferably an alkyl group having 10 or less carbon atoms, R ₂ and R ₃ are preferably an alkyl group having 5 or less carbon atoms or hydrogen, and more preferably at least one of R ₂ and R ₃ is hydrogen. It is.

In the crosslinked alkoxyalkylated polyamide resin used in the present invention, the degree of alkoxyalkylation is 10 to 50 mol%, preferably 20 to 4 mol%.
0 mol% is appropriate. If it is less than 10 mol%, the effect of the present invention is not sufficient, and it is difficult to dissolve in a solvent. Also, as the degree of alkoxyalkylation increases, the solubility in solvents increases, and rubber elasticity tends to increase.
If it exceeds 0 mol%, it is too soft and unsuitable as a carrier coating material.

Depending on the type of the alkoxyalkyl group,
By adjusting the degree of alkoxyalkylation, the specific resistance of the carrier can be controlled. Within the range of the above-mentioned degree of alkoxyalkylation of 10 to 50 mol%, the specific resistance of the carrier is 10 ⁸ to 10 ¹³ Ω · cm. , And a specific resistance not too high, which is one of the features of the present invention, can be obtained.

The measurement of the alkoxyalkylation ratio is carried out, for example, by the following Vieock-Schwappach method (Berichteder DeutschenChe).
mischen Gesellschaft, 63 ,
2318 (1930)).

[0046]

Embedded image As shown by the above formula, when heated with hydroiodic acid, the alkoxyl group is easily decomposed to produce an alkyl iodide. The generated alkyl iodide is absorbed by a mixed solution of sodium acetate and acetic acid containing a small amount of bromine to be converted into alkyl bromide and iodine bromide. The latter is further oxidized to iodic acid and hydrogen bromide, but excess bromine is decomposed with formic acid, hydrogen bromide is neutralized with sodium acetate, and a potassium iodide solution is added to liberate iodine with sodium thiosulfate. Titrate with solution.

As can be seen from the above chemical reaction formula, 1 mo
The presence of 1 alkoxyl group releases 3 mol of iodine, which is titrated with 6 mol of sodium thiosulphate. Assuming that the concentration of sodium thiosulfate used for titration is 0.1 (N) and the titer is x (ml), this corresponds to sodium thiosulfate 0.1 × x / 1000.
(Mol), the molar amount of the alkoxyl group corresponding to this amount is

[0048]

(Equation 1) It is. Therefore, when the total amount of a sample (molecular weight M) containing an alkoxyl group is represented by S (g),

[0049]

(Equation 2) Becomes

The alkoxyalkylation ratio is determined as described above.

As an example of the synthesis of an alkoxyalkylated polyamide resin, for example, 50 g of a nylon-6 resin is mixed with formic acid 2
The mixture is placed in a mixed solvent of 50 g of acetic anhydride and dissolved by stirring. 15 g of paraformaldehyde and 1 part of methanol
Add 5 g, heat to 60 ° C. and react for 5 hours. Next, the reaction solution is cooled to room temperature, opened in 5 liters of acetone, and reprecipitated and filtered to obtain a white reaction product. This product is stirred and washed in a large amount of water, and filtered at 40 ° C., 10 to 20 m.
After drying under reduced pressure at mHg, 54.1 g of methoxymethylated nylon 6 (alkoxyalkylation ratio: 30.
6 mol%).

Here, an alkoxyalkylated polyamide resin serving as the main chain of the crosslinked alkoxyalkylated polyamide resin used in the present invention will be exemplified.

[0053]

[Table 1] The coating resin used in the present invention is obtained by further crosslinking the above-mentioned alkoxyalkylated polyamide.

As the carrier coating resin, the crosslinked alkoxyalkylated polyamide resin of the present invention can be used alone, but it can be mixed with other resins used for coating the carrier. It can also be used.

Next, the crosslinking of the alkoxyalkylated polyamide resin will be described.

The alkoxyalkylated polyamide resin synthesized by the above-mentioned method and an organic acid such as citric acid, adipic acid, tartaric acid, maleic acid or hypophosphorous acid are dissolved in the same solvent. Alms,
The self-crosslinking reaction using an acid as a catalyst proceeds to form a crosslinked body. Regarding where in the molecule the cross-linking reaction takes place, the acid is used as a catalyst to decompose the alkoxyalkyl group and self-cross-link to form a cross-linked product. Therefore, in order for the polyamide resin of the present invention to exhibit its original properties, it is essential that the polyamide resin retains a predetermined amount of an alkoxyalkyl group, and in order to do so, the reaction is controlled so as to partially crosslink. There is a need to.

As the method, the type of acid serving as a catalyst for the crosslinking reaction is selected, or the crosslinking temperature is changed by controlling the reaction temperature, or the loss due to crosslinking is anticipated.
There are adjustment methods such as increasing the alkoxyalkyl group content in advance.

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 monomer referred to here include 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-chloro styrene,
3,4-dichlorostyrene, m-nitrostyrene, o-
Styrene derivatives such as nitrostyrene and p-nitrostyrene, and ethylene and unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene;
Unsaturated diolefins such as butadiene and isoprene;
Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methacrylic acid and methyl methacrylate, ethyl methacrylate, and propyl methacrylate , N-butyl methacrylate,
Isobutyl methacrylate, n-octyl methacrylate,
Α-methylene aliphatic monocarboxylic esters such as dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate;
Acrylic acid and methyl acrylate, ethyl acrylate,
Acrylic esters such as n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, 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-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; Among them, those polymerized by using one or more of them are used.

In addition to resins obtained by polymerization from 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, and the like. And a mixture of the above-mentioned vinyl resin.

The magnetic material used for the magnetic fine particles constituting the carrier core material in the present invention includes, for example, ferromagnetic metals such as iron, cobalt and nickel, ferrite, and the like.
Examples include alloys or compounds containing elements exhibiting ferromagnetism such as iron, cobalt, and nickel such as magnetite and hematite. The saturation magnetization of the magnetic fine particles according to the present invention is 60 emu / g under a magnetic field of 10 K Oersted.
That is all. When the content is less than 60 emu / g, even if the content of the magnetic fine particles is increased, the carrier tends to easily adhere to the photoreceptor. The magnetic force was measured using VSM manufactured by Toei Kogyo Co., Ltd.

The magnetic fine particles according to the present invention preferably have a primary average particle diameter of 2.0 μm or less. When the primary average particle size exceeds 2.0 μm, the surface of the core material does not become dense, and the coating with the coating resin of the carrier core material used in the present invention does not tend to be in a uniform state. there were. Furthermore, in the carrier of the present invention, the content based on the total amount of the carrier is 30% by weight.
It is necessary to be at least 50% by weight. When the content is less than 30% by weight, carrier adhesion to the photoreceptor is likely to occur, and it is difficult to control the specific resistance of the carrier.

One of the important characteristics of the magnetic material-dispersed carrier of the present invention is the charge controllability of the toner. The use of the above coating resin in the present invention makes it possible to control the specific resistance of the carrier appropriately, and it is possible to prevent the charge-up phenomenon of the toner particularly under low humidity.

The specific resistance of the magnetic fine particles is required to be 10 ⁹ Ω · cm or less for controlling the specific resistance of the carrier in the present invention. The specific resistance of the magnetic fine particles was measured according to the method of measuring the specific resistance of the carrier described later.

The average particle size of the carrier particles of the present invention is 10 to 10.
Preferably, it is used in a range of 60 μm. When the carrier particle size is less than 10 μm, the carrier tends to easily adhere to the photoreceptor. When the carrier particle size is more than 60 μm, the share of the developer in the developing device becomes large, and the deterioration of the developer, particularly the toner particle There is a tendency that exfoliation and shape change of the external additive are easily caused. Furthermore, when the particle size is large, the specific surface area is small, so that the amount of toner that can be retained when constituting the developer is small, and an image lacking in definition is obtained. The particle size of the carrier used in the present invention is indicated by the maximum chord length in the horizontal direction, and the measuring method is randomly selected from 300 or more carriers by a microscope, and the diameter is measured to obtain the carrier particle size 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 impossible to obtain a magnetic force sufficient to suppress carrier adhesion to the photoconductor. The true specific gravity of the carrier used in the present invention was measured with a trudenser (manufactured by Seishin Enterprise).

The specific resistance of the carrier used in the present invention is 10 ⁸
The range of from 10 to 10 ¹³ Ω · cm is appropriate. 10 ⁸ Ω · cm
If the value is less than the above, current leaks from the sleeve to the surface of the photoreceptor in the developing region in the developing method in which a bias voltage is applied, so that a good image cannot be obtained. Also 10 ¹³ Ω
If it exceeds cm, a charge-up phenomenon is caused under conditions such as low humidity, which causes image deterioration such as density loss, transfer failure and fog.

In the present invention, the specific resistance was measured by the measuring method shown in FIG. That is, cell A
Is filled with a carrier, electrodes 1 and 2 are arranged so as to be in contact with the filled carrier, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a specific resistance ρ (Ω · c
m) was used. In the above measuring method,
Since the carrier is a powder, a change in the filling rate occurs, and the specific resistance may change with the change. The conditions for measuring the specific resistance in the present invention were as follows: the contact area S between the filled carrier and the electrode was about 2.3 cm ² , the thickness d was about 1 mm, the load on the upper electrode 2 was 275 g, and the applied voltage was 100 V.

In order to keep the specific resistance of the carrier of the present invention within the above range, the low specific resistance core material containing the magnetic fine particles is coated with the coating resin of the present invention so that the specific resistance can be easily reduced. Is a feature of the present invention. It is a feature of the present invention that the specific resistance can be controlled by using the coating structure as a uniform coating. That is, the surface exposure state of the magnetic fine particles in the core material and the coating state of the coating resin are closely related to the characteristics of the carrier. If present, the image tends to be disturbed. Therefore, it is necessary to keep the resistance of each part of the carrier surface almost uniform by uniform resin coating in order to obtain good developability, and this is also a feature of the present invention.

In order to make the resistance of each part of the surface of the core material uniform, it is considered preferable that the magnetic fine particles are uniformly dispersed in each part of the surface of the core material. However, when the dispersion state of the magnetic fine particles in the core material was observed with a scanning electron microscope, the carrier in the present invention was such that the magnetic fine particles were uniformly dispersed at each site on the surface of the core material, and the surface of the magnetic fine particles was The present inventors have found that at least a part thereof is substantially exposed on the surface of the core material.

In the present invention, the sphericity of the carrier (long axis /
The short axis is desirably 2 or less. When the sphericity of the carrier in the present invention exceeds 2, the effect of reducing the share of the developer and the effect of improving the fluidity of the developer tend to decrease. Accordingly, the sphericity is desirably 2 or less in order to prevent the deterioration of the developer which can be achieved by the carrier in the present invention and the effect of improving the developing characteristics.

Means for achieving the above-mentioned sphericity of 2 or less in the carrier of the present invention include a method of heating the core material and thermally melting the surface to form a sphere, or a method of mechanically forming a sphere. Alternatively, the method of producing the core material is as follows: magnetic particles, a polymerization initiator, a suspension stabilizer, and the like are added to a monomer solution of a binder resin used in the core material, and then dispersed and granulated and polymerized. If the usual suspension polymerization method for obtaining the material is used, the sphericity of the carrier can be achieved 2 or less without performing the treatment on the core material.

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

The method of manufacturing a carrier according to the present invention comprises two steps of preparing a core material and applying a resin coating.

First, as a method of manufacturing a core material, the binder resin and the magnetic fine particles are mixed at a desired quantitative ratio.
Kneading at an appropriate temperature using a hot-melt mixing device such as a three-roll or extruder, cooling, and then pulverizing and classifying, or dissolving the binder resin in a soluble solvent, After mixing the fine particles to form a slurry, granulating and drying using a spray drier, or magnetic fine particles, a polymerization initiator, a suspension stabilizer, etc. in a monomer solution of the binder resin for the core material. There is a suspension polymerization method of adding, dispersing, and then granulating and polymerizing. In particular,
According to the polymerization method, it is not only easy to control the sphericity to 2 or less, but also to uniformly disperse the magnetic fine particles at each site on the surface of the core material and to form at least one surface of the magnetic fine particles. Since the portion can be controlled to be substantially exposed to the surface of the core material, it is a more preferable method for producing the core material for obtaining the effects of the present invention.

Next, as a method of coating the core material with a resin,
Considering that the core material is composed of a resin, a treatment method in which the coating resin is rapidly coated so that the core materials do not adhere to each other is desirable, and selection of a solvent that dissolves the coating resin and treatment temperature, time, etc. It is preferable to use a treatment method in which the coating and drying are simultaneously advanced in such a manner that the conditions are sufficiently controlled and the core material is constantly fluidized.

A specific example of the method will be described below.

First, 0.45 parts by weight of citric acid is dissolved in 85 parts by weight of methanol. In this solution, 15 parts by weight of the alkoxyalkylated polyamide resin (1) is dissolved.
This solution is applied as a carrier coating solution to a carrier core material composed of a magnetic material having an average particle size of 45 μm and a binder resin using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.).
After pre-drying at 70 to 80 ° C after application to evaporate the solvent, heat treatment is performed at 120 to 130 ° C for 5 to 10 minutes. The degree of cross-linking of the coating resin of this carrier was calculated from the amount of the disappeared alkoxyalkyl group using the above-mentioned method for measuring the alkoxyalkylation ratio, and was 8.2 mol%.

The amount of the coating resin differs depending on the true specific gravity of the core material. When the true specific gravity of the carrier is set to X, the optimum value of the coating resin needs to satisfy the following relational expression.

1 / 2X ≦ Coating resin amount ≦ 50 / X (% by weight) More preferably, 1 / X ≦ Coating resin amount ≦ 25 / X (% by weight).

That is, if the amount of the coating resin is less than 1 / 2X wt%, it is difficult to uniformly coat the surface of the core material because the amount of the coating resin is small. Does not hold. On the other hand, if it exceeds 50 / X% by weight, it is difficult to coat uniformly because the amount of the coating resin is too large, and a surplus coating resin tends to be present alone in the carrier. Therefore, not only is it impossible to control the resistance to the optimum value, which is a feature of the present invention, but also there is a tendency that the developability is deteriorated due to the adhesion of the excess coating resin in the developer to the photoreceptor.

The two-component developer for developing an electrostatic image of the present invention comprises 10 to 1000 parts by weight, preferably 30 to 50 parts by weight of the above-mentioned magnetic substance-dispersed carrier with respect to 10 parts by weight of the toner.
0 parts by weight are preferably mixed and used.

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

Further, in terms of resolution and toner consumption, the toner according to the present invention has a toner particle size distribution
It is preferably 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
Is preferably 1 to 30% by number of the total number of particles, and particles having a particle size of 16 μm or more are preferably less than 2.0% by volume of the total number of particles.

The preferred constitution of the toner according to the present invention will be described in more detail.

As described above, the toner particles having a particle size 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% by number.
~ 50% by number is good. If the toner particles having a particle diameter of 5 μm or less are less than 17% by number, the amount of toner particles effective for high image quality is small. In particular, as the toner is used by continuing copy or printout, the effective toner particle component is reduced. As a result, the balance of the particle size distribution of the toner deteriorates, and the image quality gradually decreases. If it exceeds 60% by number, the toner particles tend to aggregate with each other,
Since the toner mass becomes larger than the original particle size, the image quality becomes rough, the resolution is reduced, the difference in density between the edge portion and the inside of the latent image is increased, and the image tends to be slightly hollow.

The toner particles having a particle size in the range of 8 to 12.7 μm are, as described above, 1 to 30% by number, preferably 1 to 23% by number.
It is preferably a number%, more preferably 8 to 20 number%. If it is more than 23% by number, especially 30% by number
When the ratio exceeds, the image quality is deteriorated, and unnecessary development (that is, excessive toner application) occurs, which causes 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 density. N / V between the number% (N%) and the volume% (V%) of the toner particle group having a particle size of 5 μm or less.
= −0.04N + k, where 4.5 ≦ k ≦ 6.
Indicates a positive number in the range of 5. Preferably, 4.5 ≦ k ≦ 6.
0, more preferably 4.5 ≦ k ≦ 5.5. As indicated above, 17 ≦ N ≦ 60, preferably 25 ≦ N ≦
50, more preferably 30 ≦ N ≦ 50.

When k <4.5, the number of toner particles having a particle diameter smaller than 5.0 μm is small, and the image density, resolution, and sharpness are poor. The appropriate presence of fine toner particles, which was conventionally considered unnecessary, contributes to the closest packing of the toner in the development and contributes to forming a uniform image without roughness. In particular, by uniformly filling the fine lines and the outline of the image, the sharpness is further enhanced visually. If k <4.5, these characteristics are inferior due to the lack of the particle size distribution component.

From another aspect, in order to satisfy the condition of k <4.5 in production, it is necessary to cut a large amount of fine powder by means such as classification, which is disadvantageous in terms of yield and toner cost. It will be. If k> 6.5, the image density tends to decrease as copying is continued due to the presence of unnecessarily fine powder. Such a phenomenon is caused by excessive fine-powder non-magnetic toner particles having an unnecessary charge being charged and adhered to the developing sleeve or / and the carrier, causing normal non-magnetic toner to be carried on the developing sleeve or the carrier and charged. It is thought to be caused by inhibiting the application.

As described above, the content of the toner particles having a particle size of 16 μm or more is preferably less than 2.0% by volume, more preferably 1.0% by volume or less, and further preferably 0.5% by volume or less. It is. When the content is more than 2.0% by volume, not only does it hinder the reproduction of fine lines, but also, in the transfer, 16 μm is applied to the thin layer surface of the toner particles developed on the photoreceptor.
m or more of the coarse toner particles protrude,
The delicate state of contact between the photoreceptor and the transfer paper via the toner layer is made irregular, causing fluctuations in the transfer conditions and causing poor transfer images.

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

As the measuring device, Coulter Counter T
An interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution using A-II type (manufactured by Coulter) and CX
-1 Connect a personal computer (Canon),
As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. The measuring method is 100 to 100
To 150 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, 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 using an ultrasonic disperser, and the particle size distribution of particles of 2 to 40 μm based on the number was measured using the Coulter Counter TAII, using an aperture of 100 μm as an aperture. Was measured, and then a value according to the present invention was determined.

As the binder resin used in the toner according to the present invention, the following binder resins for toner can be used when a heating and pressing roller fixing device having an oil application device is used.

For example, homopolymers of styrene and its substituted substances such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, 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 Copolymers: polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, cumarone indene resin, and petroleum resin.

In the heat and pressure roller fixing method in which almost no oil is 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 is a problem.
These problems must be taken into account at the same time because toners that fix with less heat energy tend to block or cake during storage or in a developer. 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 copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Double bonds such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide Or a substituted product thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, or dimethyl maleate and a substituted product thereof; for example, vinyl chloride, vinyl acetate, vinyl benzoate Vinyl esters such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl methyl ether and vinyl ethyl ether Ether, such as vinyl ethers vinyl isobutyl ether; such vinyl monomers are used alone or two or more.

As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used, for example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate and ethylene glycol diacrylate. Methacrylate, 1,3
A double bond such as butanediol dimethacrylate
Carboxylic acid esters having one or more divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone divinyl compound; and compounds having three or more vinyl groups are 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 the binder resin (preferably 0.05 to 5% by weight) at the time of synthesizing the binder resin from the viewpoint of offset resistance and fixability.

When the pressure fixing method is used, a binder resin for a pressure fixing toner can be used. For example, polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer,
There are ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, and paraffin.

In the toner according to the present invention, charge controllability is added to toner particles (internal addition) or mixed with toner particles (external addition).
It is preferable to use them. The charge control agent makes it possible to control the optimal charge amount according to the development system. In particular, in the present invention, it is possible to further stabilize the balance between the particle size distribution and the charge, and by using the charge control agent It is possible to further clarify the function separation and the complementarity for higher image quality for each particle size range described above. As the positive charge control agent, a modified product of nigrosine and a fatty acid metal salt; tributylbenzylammonium-1-hydroxy-4-naphthosulfonate,
Quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate; dibutyltin oxide; diorganotin oxides such as dioctyltin oxide and dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, and dicyclohexyltin borate alone or in combination of two or more be able to. Of these, charge control agents such as nigrosine and quaternary ammonium salts are particularly preferably used.

General formula

[0101]

[Formula] Or a copolymer with a polymerizable monomer such as styrene, acrylate or methacrylate as described above can be used as the positive charge control agent. In this case, these charge control agents also act as (all or part of) the binder resin.

As the negative charge controlling agent which can be used in the present invention, for example, an organometallic complex and a chelate compound are effective. Examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate, 3,5- Di-t
There is chromium tert-butylsalicylate. 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 (having no action 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 (more preferably 3 μm or less).

At the time of internal addition to the toner, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (more preferably 0.2 to 10 parts by weight) based on 100 parts by weight of the binder resin.

It is preferable to add fine silica powder to the toner according to the present invention. When the toner and the silica fine powder are combined, abrasion is remarkably reduced because the silica fine powder is interposed between the toner particles and the surface of the carrier or the sleeve. As a result, the life of the toner and the carrier and / or the sleeve can be prolonged, and a stable chargeability can be maintained. Thus, a two-component developer having more excellent toner and carrier can be used for a long time. It is possible.

In particular, in the case of a toner having a weight average particle diameter of 10 μm or less, the specific surface area is larger than that of a toner having a weight average particle diameter of more than 10 μm, and the toner particles are brought into contact with the carrier due to triboelectric charging. In this case, the number of times of contact between the toner particle surface and the carrier is increased as compared with a toner having a weight average particle diameter of more than 10 μm, so that abrasion of the toner particles and contamination of the carrier are liable to occur. By adding the powder, a good two-component developer can be obtained.

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

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

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

[0110] The silica fine powder mentioned here may be a silicate such as anhydrous silicon dioxide (colloidal silica); aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate.

Among the above-mentioned silica fine powders, those having a specific surface area of 30 m ² / g or more (particularly 50 to 400 m ² / g) measured by the BET method by nitrogen adsorption 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 according to the present invention is used as a positively chargeable toner, the fine silica powder added for preventing the toner from being worn and preventing the carrier and the sleeve surface from being stained is more negatively charged than negatively charged. It is preferable to use positively-chargeable silica fine powder without impairing the charging stability, and when using as negatively-chargeable toner, it is preferable to use negatively-chargeable silica fine powder for the same reason.

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

In the present invention, the positively-charged silica refers to a silica having a positive tribocharge with respect to the iron powder carrier when measured by a blow-off method.

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

[0116]

Embedded image (Wherein, 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 represents hydrogen, an alkyl group or an aryl group,, R ₅ Represents a nitrogen-containing heterocyclic ring.) In the above formula, an alkyl group, an aryl group, an alkylene group,
The phenylene group may have an organo group having a nitrogen atom, or may have a halogen substituent as long as the chargeability is not impaired. The silicone oil is
It is good to use 1 to 50% by weight, preferably 5 to 30% by weight, based on the silica fine powder.

The nitrogen-containing silane coupling agent used in the present invention generally has a structure represented by the following formula.

Rm-Si-Yn (R represents an alkoxy group or a halogen, Y represents an amino group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, 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.

[0119]

Embedded image

Examples of the saturated heterocyclic group include the following.

[0121]

Embedded image

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

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

The amount of the treated positive or negative silica fine powder is 0.01 to 100 parts by weight of the toner.
The effect is exhibited when the amount is from 8 to 8 parts by weight, and particularly preferably, the amount is from 0 to 8 parts by weight.
When added in an amount of 1 to 5 parts by weight, it exhibits positive or negative chargeability having excellent stability. In a preferred embodiment, the addition form is preferably such that 0.1 to 3 parts by weight of the treated silica fine powder is attached to the surface of the toner particles with respect to 100 parts by weight of the toner. The untreated fine silica powder described above can be used in the same application amount.

The silica fine powder used in the present invention may be treated with a silane coupling agent or a treating agent such as an organosilicon compound for the purpose of hydrophobicity, if necessary. It is treated with a treating 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, triorganosilyl acrylate, Vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule, one for each terminal unit There is a dimethylpolysiloxane containing a hydroxyl group bonded to Si. These are used alone or in a mixture of two or more. The treatment agent is 1 to 1 based on the silica fine powder.
It is preferred to use 40% by weight.

Instead of silica fine powder, BET specific surface area 5
Fine titanium oxide 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.

It is also possible to add a fine powder of a fluorine-containing polymer (for example, a fine powder of polytetrafluoroethylene, polyvinylidene fluoride or a tetrafluoroethylene-vinylidene fluoride copolymer) to the toner according to the present invention. It is. In particular, polyvinylidene fluoride fine powder is preferred in terms of fluidity and abrasiveness. The amount added to the toner is 0.01 to 2.0 wt%, particularly 0.02%.
To 1.5 wt% (more preferably, 0.02 to 1.0 wt%).
wt%) is preferred.

As the coloring agent, 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.
It is preferably at most 2 parts by weight, more preferably 0.5 to 9 parts by weight.
Good by weight.

The toner according to the present invention contains low-molecular-weight polyethylene, low-molecular-weight polypropylene, microcrystalline wax,
It is also a preferred embodiment of the present invention to add a waxy substance such as carnauba wax, sasol wax and paraffin wax in an amount of 0.5 to 5% by weight.

The toner according to the present invention may further contain other additives as necessary.

To prepare the toner according to 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 with a mixer such as a ball mill. After thoroughly mixing, using a hot kneader such as a heating roll, kneader, or extruder, disperse or disperse the pigment or dye in the resin mixed with each other by melting, kneading, and kneading, and cooling. After singulation, toner particles can be obtained by crushing and strict classification. The toner particles can be used as a toner as it is, 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 mixed using a mixer such as a Henschel mixer. By mixing the above, a toner can be obtained. Next, an image forming method according to the present invention will be described with reference to the developing device shown in FIG.

The latent image carrier 11 is made of an insulating drum for electrostatic recording or α-Se, CdS, ZnO ₂ , OPC, α-Si
And a photosensitive drum or a photosensitive belt having a photoconductive insulating material layer. The latent image carrier 11 is rotated in the direction of arrow a by a driving device (not shown). 22 is the latent image carrier 11
Is a developing sleeve as a developing carrier that is in close proximity to or is in contact with, and is made of, for example, a nonmagnetic material such as aluminum or SUS316. The developing sleeve 22 has a horizontally long opening formed in the longitudinal direction of the container on the lower left wall of the developing container 36, with a substantially right half circumferential surface protruding into the container 36, and a left substantially half circumferential surface being exposed outside the container to be rotatably supported. It is provided horizontally and is driven to rotate in the direction of arrow b.

Reference numeral 23 denotes a fixed permanent magnet (magnet) as a fixed magnetic field generating means inserted into the developing sleeve (developing carrier) 22 and positioned and held in the position and orientation shown in the figure.
Even when the developing sleeve 22 is driven to rotate, the magnet 23 is fixedly held at the position and posture shown in the drawing. This magnet 2
Numeral 3 has four magnetic poles: an N pole 23a, an S pole 23b, an N pole 23c, and an S pole 23d. Magnet 23
May be provided with an electromagnet instead of a permanent magnet.

Reference numeral 24 denotes a base fixed to the side wall of the container on the upper edge side of the developer supply opening on which the developing sleeve 22 is disposed, and the front end side is projected to the inside of the container 36 from the position of the upper edge of the opening. A non-magnetic blade as a developer regulating member disposed along the longitudinal direction, for example, a SUS 316 formed by bending a SUS 316 into a cross-shaped cross section.

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

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

Reference numeral 30 denotes an anti-scattering electrode plate for applying a voltage of the same polarity as that of the developing agent to the floating developer generated in the developing step so as to adhere to the photoreceptor side to prevent scattering.

Reference numeral 60 denotes a toner density 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 toner 37 is mixed and stirred while being conveyed by the screw 61. Accordingly, a tribo is applied to the replenished toner during this conveyance. 63 is a cut-out plate which is cut out at both ends in the longitudinal direction of the developing device,
In this part, the fresh developer conveyed by the screw 61 is delivered to the screw 62.

The S magnetic pole 23d is a transport pole. The collected developer after the development is collected in the container, and the developer in the container is further transported to the regulating section.

In the vicinity of 23d, the fresh developer conveyed by the screw 62 provided near the sleeve and the recovered developer after development are exchanged.

Numeral 64 denotes a conveying screw for making the amount of the developer uniform in the developing sleeve axial direction.

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 to 900 μm.
50 to 800 μm, more preferably 400 to 800 μm
It is. If the distance is less than 100 μm, magnetic particles described later are clogged in the meantime, and the developer layer is likely to cause unevenness, and the developer necessary for good development cannot be applied, and the density of the developed image is low and uneven. There is a disadvantage that can only be obtained. d is preferably 400 μm or more in order to prevent non-uniform coating (so-called blade jam) due to unnecessary particles mixed in the developer. If the thickness is larger than 900 μm, the amount of the developer applied on the developing sleeve 22 increases, and a predetermined developer layer thickness cannot be regulated. As a result, the amount of magnetic particles attached to the latent image carrier increases, and There is a disadvantage in that the regulation of development by the developer limiting member 26 is weakened, and toner tribo is insufficient and fogging is likely to occur.

[0143] The imaginary line connecting the center and the magnetic pole 23a of the developing sleeve 22 and L _1, the imaginary line connecting the tips of the non-magnetic blade 24 of the center and the developer regulating member of the developing sleeve 22 is taken as L _2, the angle made a virtual line by L ₁ and L ₂ and theta _1.

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

In this magnetic particle layer, the sleeve 22
Even when the sleeve 22 is driven to rotate in the direction, the movement becomes slower as the distance from the sleeve surface increases due to the balance between the magnetic force and the restraining force based on gravity and the conveying force in the moving direction of the sleeve 22. 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 particle layer is conveyed toward the magnetic pole 23a toward the magnetic pole 23a to form a moving layer as being closer to the sleeve. Due to the movement of the magnetic carrier, the magnetic carrier is conveyed to the developing area with the rotation of the sleeve and used for development.

At this time, it is preferable to make the thickness of the developer layer on the developing sleeve 22 equal to or slightly larger than the gap distance e between the developing sleeve 22 and the latent image carrier 11, and to apply an alternating electric field to this gap. . This distance e is 50 to 8
00 μm (more preferably, 100 to 700 μm) is good.

By applying a developing bias in which an alternating electric field or a DC electric field is superimposed on the alternating electric field between the developer sleeve 22 and the latent image carrier 11 by a bias power supply, the toner from the developer sleeve 22 to the latent image holding member 11 is applied. Can be easily moved, and a high-quality image can be formed.

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

Here, the method of measuring the triboelectric charge amount of the toner with respect to the carrier in the present invention will be described in detail with reference to FIG.

FIG. 3 is an explanatory view of a device for measuring the amount of triboelectric charge. In FIG. 3, a metal measuring container 72 having a conductive screen 71 of 400 mesh (which can be appropriately changed to a size that does not allow the passage of carrier particles) has a magnetic material on a developer carrier whose frictional charge amount is to be measured. A brush (a mixture of toner and magnetic particles) is put in and a metal lid 73 is formed. The weight of the measuring container 72 overall in this state is weighed and is expressed W _1. Next, in the suction device 74 (at least the portion in contact with the measurement container 72 is at least an insulator), the air is suctioned from the suction port 75 and the air volume control valve 76 is adjusted to adjust the pressure of the vacuum gauge 77 to 70 mmHg. In this state, suction is sufficiently performed (about 1 minute) to remove toner by suction. The potential of the electrometer 78 at this time is set to V (volt). Here, 79 is a capacitor whose capacity is C
(ΜF). 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 as in the following equation.

Q (μc / g) = C × V / (W ₁ −W ₂ ) where the measurement conditions are 23 ° C. and 60% RH.

[0153]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. This does not limit the invention in any way. The percentages and parts in the following formulations are all percentages by weight and parts by weight.

Example 1 Styrene 22.2% 2-ethylhexyl acrylate 11.1% Reduced iron (particle diameter 0.32 μm) 66.7% The above materials were heated in a vessel to a temperature of 70 ° C. and dissolved. This was a monomer mixture. 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% PVA aqueous solution and stirred at 70 ° C. with a homogenizer at 4500 rpm for 10 minutes to granulate the composition. Then, while stirring with a paddle stirrer, 70 ° C, 1
Polymerization was performed for 0 hours. After the completion of the polymerization reaction, the reaction product was cooled, and the obtained magnetic material-dispersed styrene acrylic slurry was washed and filtered. This was dried to obtain magnetic material-dispersed resin particles. The true specific gravity of the obtained magnetic material-dispersed resin particles, that is, the core material, was 2.4.

In the resin example (1) in Table 1 described above, 15 parts were dissolved in advance with 0.3 part of citric acid so that the amount of resin coated on the core material was 1.5% from the above formula. Was dissolved in 85 parts of methanol to prepare a carrier coating solution.

The carrier coating solution was applied to the above-mentioned core material while being dried while being applied by a coating machine (Spira Coater, manufactured by Okada Industry Co., Ltd.). The obtained coated magnetic substance-dispersed resin carrier 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 cover the core material surface with a resin coating layer. A mold resin carrier was obtained. When the obtained resin-coated magnetic substance dispersed resin carrier was observed by an electron microscope, the core material was uniformly coated with the resin, and the magnetic particles were substantially uniformly exposed on the coated surface. It was confirmed that.

The carrier obtained had a particle size of 48 μm.

The obtained carrier was subjected to room temperature and normal humidity (23 ° C.).
/ 60% RH), low-temperature and low-humidity (15 ° C / 10% RH), and high-temperature and high-humidity (32.5 ° C / 90% RH) for 4 days, and the specific resistance was measured by the method of FIG. , 7.7
× 10 ⁹ Ω · cm, 2.4 × 10 ¹⁰ Ω · cm and 2.1
× 10 ⁹ Ω · cm.

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 mixture was melt-kneaded at least twice or more with this roll mill, cooled, and coarsely pulverized to a particle size of about 1 to 2 mm using a hammer mill. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain a negatively triboelectrically charging cyan powder having a weight average particle size of 8.6 μm. 100 parts of the above colored powder and 0.5 part of silica fine powder subjected to hydrophobic treatment with hexamethyldisilazane were mixed to obtain a cyan toner.

This cyan toner and the above carrier were mixed (toner concentration: 5%) to prepare a developer, and a full-color laser copying machine CLC-500 (manufactured by Canon Inc.) was used, which was set at a development contrast of 350 V and an AC electric field of 1800 Hz-2000 V. Image formation tests were performed under various environments.

As a result, the image reflection density was 1.55 at normal temperature and normal humidity, 1.49 at low temperature and low humidity, and 1.5 at high temperature and high humidity.
7, each of which was sufficiently high, and a clear and excellent gradation image was obtained. Further, when the charge amount of the toner under each environment at this time was measured, it was -32.0 μc / g at normal temperature and normal humidity.
−33.52 μc / g under low temperature and low humidity, −3 under high temperature and high humidity
The variation of the charge amount of the toner was small even due to environmental fluctuation of 0.7 μc / g.

The developer was obtained by mixing the cyan toner and the resin carrier so that the toner concentration was 5% under an environment of temperature / humidity of N / N (23 ° C./60% RH). 100 g of the obtained developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. Thereafter, the developer was taken out, and the developer was observed with an electron microscope. As a result, no detachment of the magnetic material from the carrier, no peeling of the coating material, and no filming by the toner were observed.

A developer was obtained by mixing the cyan toner and the above-mentioned resin carrier in a temperature / humidity environment of L / L (15 ° C./10% RH) so that the toner concentration was 5%. This was put in a developing device for CLC-500 as shown in FIG. 2 under the same environment, and idle rotation was performed for 30 minutes by driving an external motor (peripheral speed: 300 rpm). Thereafter, using CLC-500,
Development contrast 350 V, development bias AC voltage 2
An image was displayed at 000 Vpp and an AC frequency of 2000 Hz. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was also good.

Comparative Example 1 Styrene-methacrylic acid 2-
Hydroxyethyl-methyl methacrylate copolymer (monomer composition weight ratio 25: 10: 6)
5) The above resin material is dissolved in a toluene solution, and the resin solid content is 10%.
Was prepared. This solution was applied to spherical ferrite particles having an average particle size of 48 μm in the same manner as in Example 1. The coated carrier was heated at 80 ° C. for 1 hour to remove the solvent, and then dried by heating at 140 ° C. for 2 hours to obtain a resin-coated carrier. The resin coverage of the obtained carrier is 0.87%
Met.

The specific resistance of this carrier in each environment was measured in the same manner as in Example 1. 3.6 × 10 under normal temperature and normal humidity
¹⁵ Ω · cm, 2.2 × 10 ¹⁶ Ω · cm under low temperature and low humidity,
Under high temperature and high humidity, it was 7.7 × 10 ¹² Ω · cm, which was largely changed due to environmental fluctuation.

Next, this carrier and the cyan toner were mixed at a toner concentration of 5% to prepare a developer, and an image forming test was performed in various environments using CLC-500 set to a developing contrast of 350 V. . As a result, the reflection image density was 1.43 under normal temperature and normal humidity, and 1.2 under low temperature and low humidity.
1. Under high temperature and high humidity, the reflection image density greatly changed due to environmental fluctuations of 1.71. Further, the obtained image had many fogs and lacked sharpness. At this time, the charge amount of the toner under each environment was measured.
The charge amount of the toner greatly changed due to environmental fluctuations, 8.2 μc / g, -66.1 μc / g under low temperature and low humidity, and −18.9 μc / g under high temperature and high humidity.

A polybin shaking test using a turbula mixer was performed in the same manner as in Example 1. When the developer after shaking was observed with an electron microscope, toner filming was partially observed on the carrier surface. The silica externally added to the toner surface was partially peeled off. Further, when the same idling test was performed as in Example 1, a decrease in the density of the solid image and a rough image of the halftone image were observed.

(Comparative Example 2) 6,66,610 copolymerized nylon (weight average molecular weight 155,000, weight composition ratio 6 /
(66/610 = 2/2/1) was dissolved in 95 parts of methanol so that the coating resin amount was 0.9% to prepare a carrier coating solution. This solution was applied to the magnetic material-dispersed resin particles used in Example 1 in the same manner as in Example 1, and dried to obtain a resin-coated carrier.

Observation of the surface of the carrier with an electron microscope revealed that the coating on the protruding portion of the core material was thin and was not uniformly coated. The resulting carriers were allowed to stand for 4 days in a normal temperature, normal humidity, low-temperature, low-humidity, and high-temperature, high-humidity environment, and the specific resistance was measured.
10 ¹⁴ Ω · cm, 4.8 × 10 ¹⁵ Ω · cm, 8.4 × 1
0 ¹¹ Ω · cm.

A test similar to that of Example 1 was performed using this carrier. As a result, in an image forming test using CLC-500, the image reflection density was 1.25 under normal temperature and normal humidity, 0.72 under low temperature and low humidity, and 1.3 under high temperature and high humidity.
9 and a low and rough image was obtained in any environment. When the charge amount of the toner at this time was measured, it was -48.1 μc / g under normal temperature and normal humidity, -80.0 μc / g under low temperature and low humidity, and -42.1 μc / g under high temperature and high humidity.
And the environment, the amount of charge of the toner greatly fluctuated.
Next, a shaking test was performed with a turbula mixer and the developer was observed with an electron microscope. As a result, toner filming was observed on the carrier surface, and a part of the carrier coating resin was peeled off. Next, in the idle rotation test using a developing device for CLC-500, the solid image is considerably faint compared to the initial stage and the density is lowered, and in the halftone portion, roughness is conspicuous and the image quality is deteriorated. Was.

(Example 2) Phenol 10.0% Formaldehyde (about 37% formaldehyde, about 10% methanol, remainder water) 5.0% Magnetite (particle diameter 0.25 μm) 85.0% The above material was used as a basic catalyst. , Ammonia was used as a polymerization stabilizer, and calcium fluoride was used as a polymerization stabilizer, and the mixture was gradually heated to a temperature of 80 ° C while stirring in an aqueous phase, and polymerization was performed for 2 hours. The average particle size of the obtained core material was 44 μm. Next, the above-mentioned resin example (2) was coated with a coating resin amount of 1.2%.
Thus, 15 parts were dissolved in 85 parts of methanol in which 0.5 part of citric acid was dissolved to prepare a carrier coating solution.
This solution was applied to the core material in the same manner as in Example 1,
A resin-coated carrier was obtained through a drying step.

The obtained carrier was subjected to room temperature and normal humidity (23 ° C./6
0% RH), low temperature and low humidity (15 ° C./20% RH), and high temperature and high humidity (32.5 ° C./80% RH) for 4 days, and the specific resistance was measured by the method of FIG. 7.2 × 10 ¹⁰ Ω · cm under normal temperature and normal humidity, 2.6 × 10 2 under low temperature and low humidity
^{It was 11} Ω · cm and 9.8 × 10 ¹⁰ Ω · cm under high temperature and high humidity.

This carrier and a black toner (binder resin: styrene-based copolymer, paraffins: 100 parts, colorant:
Carbon black: 9 parts, charge control agent: negatively chargeable metal-containing complex: 3 parts, weight average particle size: 8.3 μm), and
(Toner concentration: 2%), a developer was prepared, and image forming tests were performed in various environments using a copying machine NP-5000 (manufactured by Canon Inc.) having a developing device shown in FIG. Is 1.35 under normal temperature and normal humidity, and 1.35 under low temperature and low humidity.
31 and 1.37 at high temperature and high humidity, respectively, and clear images were obtained. At this time, the triboelectric charge of the toner was measured to be −8.0 μc / g under normal temperature and normal humidity, −8.3 μc / g under low temperature and low humidity, and −7.2 μc / g under high temperature and high humidity. Was substantially independent of the difference between the two.

Further, when a copying durability test of 200,000 sheets was performed at room temperature and normal humidity using this developer, an image reflection density of 1.32 was obtained, and a clear image was obtained even after 200,000 sheets. Was done. Observation of the carrier surface with an electron microscope revealed that there was no deterioration such as toner spent or peeling of the coating resin.

(Example 3) A carrier similar to that used in Example 2 and a red toner for color reproduction of NP-4835 color by Canon Copier Co., Ltd. were mixed (toner concentration: 8%) to prepare a developer.
When an image forming test was performed using NP-4835, the image reflection density was as high as 1.25 under normal temperature and normal humidity, 1.23 under low temperature and low humidity, and 1.24 under high temperature and high humidity, and there was no fog. A clear image was obtained. At this time, the toner has a triboelectric charge of +17.6 μc / g under normal temperature and normal humidity, +18.2 μc / g under low temperature and low humidity, and +17.5 μc under high temperature and high humidity.
c / g, which was stable without substantially depending on the difference in environment. Furthermore, when a copying durability test was performed at room temperature and normal humidity using the above developer, the image reflection density was sufficiently high at 1.22 even after 10,000 sheets of durability, and a clear image free from fog and scattering was obtained. Was obtained.

Further, after collecting the developer after the endurance of 10,000 sheets, separating only the carrier, the surface was observed by an electron microscope. No carrier deterioration such as toner filming or peeling of the coating resin was observed.

Example 4 Polyester resin obtained by condensing propoxylated bisphenol with fumaric acid 100 parts Phthalocyanine pigment 5 parts Chromium complex salt of di-tert-butylsalicylic acid 4 parts Pre-mixed, melt-kneaded at least twice with a three-roll mill, cooled, coarsely pulverized with a cutter mill, and finely pulverized with a fine pulverizer using a jet stream, and the obtained finely pulverized powder is obtained. The powder was classified by a fixed-wall air classifier to produce a classified powder. In addition, the obtained classified powder is multi-divided using the Coanda effect (Nippon Mining Co., Ltd. elbow jet classifier)
Then, the ultrafine powder and the coarse powder were strictly classified and removed at the same time to obtain a cyan fine powder (toner) having a weight average particle size of 7.6 μm. Table 2 shows the particle size distribution of this toner.

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

Example 1 was repeated except that the cyan toner obtained as described above was used instead of the cyan toner used in Example 1.
When the test was conducted in the same manner as in Example 1, the same results as in Example 1 were obtained. In particular, the resolution and the toner consumption were more excellent than Example 1.

[0180]

[Table 2]

[0181]

As described above, when the magnetic carrier coated with the coating resin used in the present invention is used, (1) Spent resistance (2) Impact resistance (prevention of carrier destruction) (3) Deterioration of toner (4) Developability (5) Prevention of carrier adhesion on photoreceptor (6) Control of carrier resistance (7) Stable chargeability of toner during running and fluctuations in humidity can be sufficiently satisfied. High-quality images can be stably provided over a long period of time.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram illustrating 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 the toner of the two-component developer of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower 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 regulating member (non-magnetic blade) Reference Signs List 26 Magnetic carrier limiting member 27 Magnetic carrier 30 Anti-scattering electrode plate 36 Developing container 37 Toner 40 Seal member 60 Toner supply roller 61 Screw 62 Screw 63 Stripper plate 64 Conveying screw 71 Conductive screen 72 Measurement container 73 Lid 75 Suction port 74 Suction unit 76 Air flow control valve 77 Vacuum gauge 78 Electrometer 79 Condenser

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/107 G03G 9/113

Claims (9)

(57) [Claims] 1. A magnetic material-dispersed carrier comprising a core material in which magnetic fine particles are dispersed in a binder resin, and the core material surface is coated with a resin. Having a cross-linked alkoxyalkylated polyamide resin. 2. The magnetic material-dispersed carrier according to claim 1, wherein the true specific gravity of the carrier is 1.5 to 5.0. 3. The magnetic material-dispersed carrier according to claim 1, wherein the magnetic force of the magnetic material dispersed in the core material is 60 emu / g or more under a magnetic field of 10 K Oersted. . 4. The magnetic material-dispersed carrier according to claim 1, wherein the carrier has a particle size of 10 μm to 60 μm. 5. A carrier having a specific resistance of 10 ⁸ Ω · cm to 1
The magnetic material-dispersed carrier according to any one of claims 1 to 4, wherein the carrier is 0 ¹³ Ω · cm. 6. The magnetic material-dispersed carrier according to claim 1, wherein a core material obtained by dispersing magnetic fine particles in a binder resin is produced by a polymerization method. 7. An electrostatic image development comprising a magnetic material-dispersed carrier having a core material obtained by dispersing magnetic fine particles in a binder resin, the core material surface being coated with a resin, and a toner. A two-component developer for developing an electrostatic image, wherein the resin coating the surface of the core material comprises a cross-linked alkoxyalkylpolyamide resin. 8. A magnetic material-dispersed carrier in which a carrier coating solution containing a resin material is applied to a core material obtained by dispersing magnetic fine particles in a binder resin, dried, and the surface of the core material is coated with the resin. Wherein the coating solution for the carrier has a resin material and a solvent for dispersing or dissolving the resin material, and the resin material for coating the core material surface has a crosslinked alkoxyalkylated polyamide resin. A method for producing a magnetic material dispersion type carrier. 9. A two-component for electrostatic charge image development comprising a magnetic material-dispersed carrier having a core material obtained by dispersing magnetic fine particles in a binder resin and having the surface of the core material coated with a resin, and a toner. In an image forming method for developing a latent image formed on a photoreceptor by applying a bias voltage in a development area by a system developer, the resin coating the core material surface has a cross-linked alkoxyalkylated polyamide resin. An image forming method comprising: