JP3108815B2 - 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.

In addition, when the magnetic material is contained in a large amount in the magnetic material-dispersed small particle size carrier, the impact resistance becomes weak because the amount of the magnetic material increases with respect to the binder resin. When the developer is adjusted to a predetermined layer thickness on the sleeve by the developer layer thickness regulating member, or due to agitation in a developing device, the magnetic substance is likely to be missing from the carrier. In this case, there is a drawback that, since the deterioration is liable to occur, a drastic measure cannot be taken as a 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 decrease in image density due to 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 environmental stability of charging by the 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 comprising a core material surface coated with a resin, wherein the resin coating the core material surface comprises a grafted N-alkoxyalkylated polyamide resin. Career.

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 inventors of the present invention have found that the use of the magnetic material-dispersed carrier having the above-described structure provides the magnetic material-dispersed carrier with improved impact resistance, specific resistance, stability of charging toner to toner, and environmental stability. The present invention was found to be excellent, and it was found that the magnetic substance-dispersed carrier had 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. And it was difficult to coat the carrier.

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 and solubilizing it in an alcohol or the like, arbitrarily selected monomers are grafted onto the main chain nylon by graft polymerization, and the characteristics of the graft chain are adjusted with a resin. It is characterized in that the coating resin given to the above is used.

That is, ordinary nylon such as 6 nylon is
The specific resistance of 10 ¹⁴ Ω · cm or more and the very high, remains this as previously described arises the problem of charge-up, such as under a high resistance too low humidity. However, the specific resistance is 10 ⁸ to 10 ¹³ Ω by the alkoxyalkylation according to the present invention.
-It became possible to control to cm and it became soluble in the solvent, so that the coatability on the core material was improved. Further, by performing the grafting, various properties such as abrasion resistance, mechanical strength, moisture absorption resistance, and chargeability of the graft chain can be simultaneously imparted to the resin. In addition, the grafting makes the charging characteristics less affected by temperature and humidity, and is excellent in environmental stability. The reason for this is not clear, but the following structural factors can be considered.

Originally, by introducing a graft chain which becomes a side chain into an amide resin having a linear structure, (1) it is easy to be amorphous at the time of forming a film, and it is easy to hold a conductive substance such as water or ions inside the molecule; 2) In particular, when the graft portion has a polar group,
Water or ionic substances are easily absorbed and held.

Due to these points, the specific resistance does not greatly increase even in a low-temperature and low-humidity environment, and the network structure formed in an amorphous state prevents excessive incorporation of water molecules and the like into the inside of the molecule. It is presumed that the specific resistance does not decrease significantly even in a humid environment.

The graft-modified alkoxyalkylated polyamide resin that can be used in the present invention is obtained by alkoxyalkylating a polyamide resin used for the main chain by a substitution reaction, and grafting an appropriately selected monomer by a polymer reaction. Produced by By the way, in the polyamide resin used in the present invention,
When grafting, the parent polyamide resin is
Having a functional group with a high degree of activity in the molecule.

In general, the methine or methylene group in contact with the N atom of the amide bond has a considerably high degree of activity and easily undergoes radicalization. Therefore, when selecting the polyamide resin used in the present invention, the methine or methylene group contacts the N atom of the amide bond in the main chain. Those having hydrogen at a carbon atom on the main chain are preferred.

The alkoxyalkyl polyamide resin used in the present invention is a resin in which the hydrogen atom of the amide bond -NHCO- in the resin is substituted with an alkoxyalkyl group, and the alkoxyalkyl group has the following structural formula. .

[0043]

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.

The degree of alkoxyalkylation of the graft-modified alkoxyalkylated polyamide resin used in the present invention is 10 to 50 mol%, preferably 20 to 50 mol%.
40 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 the solvent increases, and the rubber elasticity tends to increase,
If it exceeds 50 mol%, it is too soft and unsuitable as a carrier coating material.

Depending on the type of 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 alkoxyalkylation ratio can be measured, for example, by the following method using the Vieock-Schwappach method (Berichteder DeutschenChe).
mischen Gesellschaft, 63 ,
2318 (1930)).

[0047]

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, potassium iodide is added, and the released iodine is dissolved in sodium thiosulfate solution. Titrate with.

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

[0049]

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

[0050]

(Equation 2) Becomes

As described above, the alkoxyalkylation ratio is determined.

The alkoxyalkylated nylon can be prepared, for example, by the following method.

(Experimental Example) 50 g of a nylon-6 resin was placed in a mixed solvent of 250 g of formic acid and 250 g of acetic anhydride and dissolved by stirring. 15 g of paraformaldehyde and 15 g of methanol are added thereto, and the mixture is heated to 60 ° C. and reacted 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., 10-20
After drying under reduced pressure under the condition of mmHg, 54.1 g of methoxymethylated nylon 6 (alkoxyalkylation rate: 3)
0.6 mol%).

The polymer reaction for grafting is performed by dissolving a polyamide resin serving as a main chain and a monomer serving as a graft component in a suitable solvent that dissolves both the polyamide resin and the monomer, and then reacts with azobisisobutylnitrile (AIB).
N), a radical initiator such as benzoyl peroxide or metal N
By adding an ionic polymerization initiator such as a, a grafted polyamide resin can be synthesized.

Since the grafted polyamide resin after the synthesis often has impurities such as an initiator residue, a purification step such as reprecipitation and washing is preferably carried out.

Examples of the monomer serving as the graft component include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-methylstyrene.
Phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, p Styrene and its derivatives such as -n-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene; ethylene, propylene, butylene,
Ethylenically unsaturated monoolefins such as isobutylene;
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 such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and phenyl methacrylate Esters: methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate Acrylates such as phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl methyl ketone;
Vinyl ketones such as vinyl hexyl ketone and methyl isopropenyl ketone; vinyl naphthalenes; and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

Although these may be used alone or in combination of two or more, it is particularly preferable to use a monomer having a polar group as described above. For example, there are vinyl halides, vinyl esters, methacrylic esters, acrylic esters, vinyl ethers, vinyl ketones, acrylic acid or methacrylic acid derivatives.

The content of the graft portion is preferably 5 to 70 parts by weight based on 100 parts by weight of the polyamide resin used in the main chain. If the amount is less than 5 parts by weight, the effect of the present invention is not sufficient. If the amount is more than 70 parts by weight, the characteristics of the polyamide resin as the main chain become insignificant.

The graft-modified alkoxyalkylated polyamide resin of the present invention can be used even if crosslinked.

As the carrier coating resin, the graft-modified alkoxyalkylated polyamide resin of the present invention can be used alone, but it is used by mixing with other resins used for coating the carrier. You can also. Hereinafter, specific synthetic examples of the graft-modified alkoxyalkylated polyamide resin will be described.

(Synthesis Example) Methoxymethylated nylon 6 synthesized by the above-described method (substitution rate of methoxymethyl group: 30.
6mol%, weight average molecular weight 105,000) 11.0
g, acrylamide 4.3 g, AIBN 0.0002 g
Was dissolved in 120 g of methanol, and the mixture was heated and stirred at 40 ° C. for 3 hours to perform a grafting reaction. Next, the reaction mixture solution cooled to room temperature was diluted with 160 g of methanol, and this was dropped into a mixed solvent of 2.0 kg of methyl ethyl ketone (MEK) and 1.2 kg of n-hexane to obtain a self-precipitated grafted polyamide. . After filtering this precipitate,
After washing three times using 600 g of MEK on a filter paper, the resultant was filtered off,
Drying under reduced pressure at 35 ° C. for 6 hours gave 13.7 g of resin (I) (graft portion content: 30.1 parts by weight).
Table 1 shows examples of the graft-modified alkoxyalkylpolyamide resin used in the present invention synthesized by the same method.

[0062]

[Table 1] * The graft portion content is represented by the following formula, where A is the amount of the graft component to be added, and B is the amount of the unreacted graft component recovered from the solution after the grafting reaction, with respect to 100 parts by weight of the main chain resin. Is represented.

Graft portion content = AB (parts by weight) In the present invention, examples of the resin used for the binder resin constituting the carrier core material include all resins obtained by polymerizing a vinyl monomer. . Examples of the vinyl monomer here include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, and 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-nitrostyrene,
styrene derivatives such as p-nitrostyrene and, for example, 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 esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methacrylic acid and methyl methacrylate, ethyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate Α-methylene aliphatic monocarboxylic esters such as n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate and phenyl methacrylate; acrylic acid and methyl acrylate; Acrylics such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate Acid esters; 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 pyrrole; N-vinyl carbazole, N-vinyl indole,
N-vinyl compounds such as N-vinylpyrrolidone; vinylnaphthalenes; acrylonitrile, methacrylonitrile,
Acrylic acid or methacrylic acid derivatives such as acrylamide; acrolein; and the like, and those obtained by polymerizing one or two or more of these 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, 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, the specific resistance of the magnetic fine particles according to the present invention must be 10 ⁹ Ω · cm or less, and the content relative to the total amount of the carrier must be 30% by weight or more, preferably 50% by weight or more. If the amount is less than 30% by weight, adhesion to the photoreceptor occurs, and it is difficult to control the specific resistance of the carrier.

Therefore, one of the important characteristics of the magnetic material-dispersed carrier of the present invention is that it can be appropriately controlled not only in that it does not adhere to the photoreceptor, but also in terms of controlling the charge amount of the toner. One. Particularly, it is characterized in that the resistance of the carrier can be appropriately controlled so as not to cause the so-called charge-up phenomenon of giving excessive charge to the toner under low humidity. Therefore, in the carrier of the present invention, the magnetic material as described above is used. The particle size, specific resistance and content of the fine particles are essential.

The average particle size of the carrier particles of the present invention is from 10 to
Preferably, it is used in a range of 60 μm. If the carrier particle size is less than 10 μm, the carrier tends to adhere to the photoreceptor, and if it exceeds 60 μm, the share of the developer in the developing device becomes large, and the deterioration of the developer, especially the external additive of the toner particles, Causes peeling and shape change, which causes image deterioration. 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. In addition, the particle diameter of the carrier used in the present invention was randomly extracted by an optical microscope at 300 or more, and the maximum chord length in the horizontal direction was defined as the carrier particle diameter.

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 of the present invention is 10 ⁸ to 10.
A range of ¹³ Ω · cm is appropriate. If it is less than 10 ⁸ Ω · cm, current leaks from the sleeve to the surface of the photoreceptor in the developing area in a developing method in which a bias voltage is applied, and a good image cannot be obtained. When it exceeds 10 ¹³ Ω · cm,
Under a condition such as low humidity, a charge-up phenomenon is caused, 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, whereby the specific resistance can be easily reduced. Is a feature of the present invention, but this feature does not always correspond to the specific resistance described above. 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 will be distorted. On the other hand, it has been found that good developability can be obtained when the resistance of each part of the carrier surface is kept substantially the same by uniform resin coating.

In order to make the resistance of each part of the surface of the core material uniform, it is 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.

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.

As means for achieving the above-mentioned sphericity of 2 or less in the carrier of the present invention, there are a method of heating the core material and thermally melting the surface to form a sphere, and 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 the 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. Note that the amount of the coating resin differs depending on the true specific gravity of the core material. If the true specific gravity of the carrier is X, the optimum value of the amount of the coating resin needs to satisfy the following relational expression.

1 / 2X ≦ Amount of coating resin ≦ 50 / X (% by weight) More preferably, 1 / X ≦ Amount of coating resin ≦ 25 / X (% by weight).

If the amount of the coating resin is less than ＸX% by weight, it is difficult to uniformly coat the surface of the core material, and even if it can be coated, it cannot be said that the carrier has sufficient strength.
On the other hand, if it exceeds 50 / X% by weight, it becomes difficult to coat uniformly, and it becomes impossible to control the resistance to an optimum value, which is a feature of the present invention. further,
The coating resin that could not be coated is liberated and generated alone and may adhere to the photoreceptor and cause image deterioration.

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, the toner according to the present invention has a toner particle size distribution in terms of resolution and toner consumption.
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 1 to 30% by number, preferably 1 to 23% as described above.
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 a 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, when a heating / pressing roller fixing device having an oil application device is used, the following binder resin for toner can be used.

For example, homopolymers of styrene and its substituted substances such as polystyrene, poly-p-chlorostyrene and polyvinyl toluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-
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

[0102]

Embedded image 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, organometallic complexes and chelate compounds are effective, and 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 function 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 and the carrier are brought into contact 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 fine silica powder 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 fine silica powder obtained by a dry method.

The dry method referred to here is, for example, a method for producing fine silica powder produced by 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.

[0111] The silica fine powder used herein can 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 fine silica powders, those having a specific surface area of 30 m ² / g or more (particularly 50 to 400 m ² / g) by nitrogen adsorption 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 according to the present invention is used as a positively chargeable toner, the silica fine powder added for preventing the toner from being worn and preventing the carrier and the sleeve 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 the silica fine powder is generally negatively charged, a method for obtaining the positively charged silica fine powder is to use the untreated silica fine powder described above with 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.

[0117]

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, the alkyl group, the aryl group, the alkylene group, and the phenylene group may have an organo group having a nitrogen atom, as long as the chargeability is not impaired. It may have a halogen substituent. The silicone oil is used in an amount of 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.

[0120]

Embedded image

Examples of the saturated heterocyclic group include the following.

[0122]

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 applied 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 has a low molecular weight polyethylene, a low molecular weight polypropylene, a 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 if 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, the 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. 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 of 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 a scattering prevention electrode plate which applies a voltage of the same polarity as that of the developer to adhere to the photoreceptor side to prevent the floating developer generated in the developing step from scattering.

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.

Reference numeral 64 denotes a conveying screw for making the amount of developer uniform 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 to 900 μm.
It is 50 to 800 μm. 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. 9
If the thickness is larger than 00 μm, the amount of the developer applied on the developing sleeve 22 increases, so that the predetermined developer layer thickness cannot be regulated, the magnetic particles adhere to the latent image carrier increases, and the 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.

[0145] 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 the magnetic particle layer, the sleeve 22 has an arrow b
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.

Accordingly, 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 it approaches 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 between the developer sleeve 22 and the latent image carrier 11 between the developer sleeve 22 and the latent image carrier 11 by a bias power source, a toner bias from the developer sleeve 22 to the latent image holder 11 is obtained by superimposing a DC electric field on the alternating electric field. 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 for 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.

[0155]

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 to 70 ° C. in a container 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.

15% of the resin example (1) in Table 1 described above was dissolved in methanol so that the amount of the resin coated on the core material was 0.9% from the above formula, and the carrier coating solution was adjusted. did.

The carrier coating solution was applied to the core material while being applied and dried by an applicator (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 3 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 obtained carrier was subjected to room temperature and normal humidity (23 ° C./6
0% 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. ¹⁰ Ω ・ c
m, 2.1 × 10 ¹⁰ Ω · cm, 1.3 × 10 ¹⁰ Ω · cm
Met.

On the other hand, 100 parts of a polyester resin obtained by condensing propoxylated bisphenol and fumaric acid 100 parts Phthalocyanine pigment 5 parts Chromium complex of di-tert-butylsalicylic acid 4 parts After the above materials were sufficiently premixed with a Henschel mixer, The mixture was melt-kneaded three times with a three-roll mill, cooled, and coarsely ground 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 is classified to obtain a negatively chargeable cyan powder (toner) having a weight average diameter of 12.3 μm.
I got

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.

The cyan toner and the resin-coated magnetic substance-dispersed carrier were mixed in each environment so that the toner concentration became 10% to obtain a developer. Using this developer, an image output test was conducted in various environments using a full color laser copying machine CLC-1 manufactured by Canon. As a result, the image reflection density was 1.63 at normal temperature and normal humidity (23 ° C./60% RH).
A clear image was obtained at 1.62 under low temperature and low humidity (15 ° C./10% RH), and 1.66 under high temperature and high humidity (32.5 ° C./90% RH). The halftone reproducibility was good in any environment. The charge amount of the toner at this time was measured.
9.7 µc / g, -20.2 µc / g under low-temperature and low-humidity, and -19.0 µc / g under high-temperature and high-humidity.

Further, using this developer, a copy durability test was performed on 30,000 sheets at room temperature and normal humidity. As a result, the image reflection density was sufficiently high at 1.62 even after 30,000 sheets, and the roughness of the halftone portion was rough. No clear image was obtained. As a result of observation of the developer after the durability test with an electron microscope, the carrier surface was free from spent toner and the coating state of the coating resin was good.

Comparative Example 1 Instead of the coating solution used in Example 1, 6,66,610 copolymerized nylon (weight average molecular weight 175,000, weight composition ratio 6/66/610 =
2/1) was dissolved in methanol so that the coating resin amount became 1.0%, and this solution was used in Example 1 using a coating machine (Spira Coater, manufactured by Okada Seiko Co., Ltd.). The coated core material was applied through the same steps as in Example 1. Observation of the carrier surface with an electron microscope revealed that the carrier was not uniformly coated.

The obtained carrier was subjected to room temperature and normal humidity (temperature 23 ° C.).
/ Humidity 60% RH), low temperature and low humidity (15 ° C / 10% R)
H) and high-temperature and high-humidity (32.5 ° C./90% RH) for 4 days, and the specific resistance was measured.
10 ¹⁴ Ω · cm, 4.2 × 10 ¹⁵ Ω · cm, 8.0 × 1
0 ⁷ Ω · cm.

Using this carrier, a developer similar to that of Example 1 was prepared, and the same evaluation as that of Example 1 was performed. As a result, the image reflection density became normal temperature and normal humidity (23 ° C./60% R
H), 1.37 under low temperature and low humidity (15 ° C./10% RH), and 1.70 under high temperature and high humidity (32.5 ° C./90% RH). Under high humidity, fog was also observed in the image. Further, the fluctuation amount of the charge amount of the toner in the three environments is large, and is −28.9 μc / at room temperature and normal humidity.
g, under low temperature and low humidity -32.8 μc / g, under high temperature and high humidity-
It was 9.3 μc / g.

(Example 2) Copolymer of styrene-2-ethylhexyl acrylate (55/45) 50% Reduced iron 50% The above materials were sufficiently premixed with a Henschel mixer, and then at least twice with a three-roll mill. After melt-kneading and cooling, the mixture was coarsely pulverized using a hammer mill to a particle size of about 2 mm. Next, it was pulverized with an air jet pulverizer to a particle size of about 50 μm. Further, the obtained finely pulverized material is put into a Mechanomill MM-10 (manufactured by Okada Seiko Co., Ltd.)
Mechanically spherical. The spheroidized finely pulverized particles were further classified to obtain magnetic substance-dispersed resin particles. The particle diameter of the obtained magnetic substance dispersed resin particles was 49 μm.

A coating resin layer similar to that of Example 1 was provided on the surface of the obtained magnetic material-dispersed resin particles to obtain a resin-coated magnetic material-dispersed carrier.

Observation of the carrier surface with an electron microscope revealed that the coating resin was uniformly coated on the core material.

The obtained carrier was subjected to room temperature and normal humidity (temperature 23 ° C.).
/ Humidity 60% RH), low temperature and low humidity (15 ° C / 10% R)
H) and a high-temperature and high-humidity environment (32.5 ° C./90% RH) for 4 days, and the specific resistance was measured.
10 ¹¹ Ω · cm, 3.5 × 10 ¹¹ Ω · cm, 1.5 × 1
0 ¹¹ Ω · cm.

Using this carrier, a developer similar to that of Example 1 was prepared, and the same evaluation as that of Example 1 was performed. As a result, the image reflection density became normal temperature and normal humidity (23 ° C./60% R
H), 1.55 under low temperature and low humidity (15 ° C./10% RH), and 1.59 under high temperature and high humidity (32.5 ° C./90% RH). Obtained. The halftone reproducibility was good in any environment. At this time, the charge amount of the toner was measured to be −21.7 μc / g under normal temperature and normal humidity, and −
The value was 23.1 μc / g, and −21.2 μc / g under high temperature and high humidity, and the fluctuation range of the charge amount with respect to environmental changes was small. Using this developer, a copy durability test of 30,000 sheets was carried out under normal temperature and normal humidity. Even after 30,000 copies, the image reflection density was sufficiently high at 1.57, and roughness of the halftone portion was observed. And a clear image was obtained. As a result of observation of the developer after the endurance with an electron microscope, the surface of the carrier was free of spent toner and the coating state of the coating resin was good.

(Example 3) Phenol 10.0% Formaldehyde (about 37% formaldehyde, about 10% methanol, remainder water) 5.0% Magnetite (particle diameter 0.25 μm) 85.0% Using the above materials as a basic catalyst Using ammonia and calcium fluoride as a polymerization stabilizer, the mixture was gradually heated to a temperature of 80 ° C. while stirring in an aqueous phase, and polymerized for 2 hours. The particle diameter of the obtained magnetic substance dispersed resin particles is 39 μm.
Met. The resin particles were provided with the same coating resin layer as in Example 1 to obtain a carrier. As a result of observation of the carrier surface by an electron microscope, it was found that the coating resin layer was uniformly coated on the core material. The obtained carrier was subjected to room temperature and normal humidity (23 ° C./60% RH), low temperature and low humidity (15 ° C./10% RH).
H) and a high-temperature and high-humidity environment (32.5 ° C./90% RH) for 4 days, and the specific resistance was measured.
10 ⁹ Ω · cm, 5.0 × 10 ⁹ Ω · cm, 2.5 × 10
It was ⁹ Ω · cm.

Using this carrier, the same developer as in Example 1 was prepared, and the same evaluation as in Example 1 was performed. As a result, the image reflection density became normal temperature and normal humidity (23 ° C./60% R
H), 1.69 under low temperature and low humidity (15 ° C./10% RH), and 1.72 under high temperature and high humidity (32.5 ° C./90% RH). Obtained. The halftone reproducibility was good in any environment. The charge amount of the toner at this time was measured to be −18.2 μc / g under normal temperature and normal humidity, and −
It was 18.9 μc / g and −17.8 μc / g under high temperature and high humidity. Further, using this developer, at room temperature and humidity, 3
When a copy durability test was performed on 10,000 copies, the image reflection density was sufficiently high at 1.67 even after 30,000 copies, and a clear image was obtained without any roughness in the halftone portion. As a result of observation of the developer after the endurance with an electron microscope, the surface of the carrier was free of spent toner and the coating state of the coating resin was good.

(Example 4) Instead of the coating solution of Example 1, 25% of the above resin example (V) was dissolved in methanol so that the coating resin amount was 0.9%, and this solution was applied to a coating machine. Example 1 Using a Spira Coater (Okada Seiko Co., Ltd.)
Was applied through the same steps as in Example 1. Observation of the carrier surface with an electron microscope revealed that the coating resin was uniformly coated on the core material.

The obtained carrier was subjected to room temperature and normal humidity (23 ° C./6
0% 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. 10 ¹⁰ Ω
cm, 1.5 × 10 ¹¹ Ω · cm, 8.1 × 10 ¹⁰ Ω · c
m.

Using this carrier, a developer similar to that of Example 1 was prepared and evaluated in the same manner as in Example 1. As a result, the image reflection density became normal temperature and normal humidity (23 ° C./60% R
H), 1.59 under low temperature and low humidity (15 ° C./10% RH), and 1.60 under high temperature and high humidity (32.5 ° C./90% RH). Obtained. The halftone reproducibility was good in any environment. At this time, the charge amount of the toner was measured to be −21.0 μc / g under normal temperature and normal humidity, and −
It was 21.5 µc / g and -20.8 µc / g under high temperature and high humidity, and was stable without substantially depending on environmental changes.
Using this developer, a copy durability test of 30,000 sheets was conducted at room temperature and normal humidity. Even after 30,000 copies, the image reflection density was sufficiently high at 1.58, and roughness of the halftone portion was observed. And a clear image was obtained. As a result of observation of the developer after the endurance with an electron microscope, the surface of the carrier was free of spent toner and the coating state of the coating resin was good.

(Example 5) Instead of the coating solution of Example 1, 15% of the above resin example (IV) was dissolved in methanol so that the coating resin amount became 1.5%. (Spira Coater, manufactured by Okada Seiko Co., Ltd.) was applied to the core material of Example 1 through the same steps as in Example 1. Observation of the carrier surface with an electron microscope revealed that the coating resin was uniformly coated on the core material.

The obtained carrier was subjected to room temperature and normal humidity (23 ° C./6
0% 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. 10 ⁹ Ω
cm, 9.2 × 10 ⁹ Ω · cm, 8.5 × 10 ⁹ Ω · cm
Met.

Using this carrier, the same developer as in Example 1 was prepared, and the same evaluation as in Example 1 was performed. As a result, the image reflection density became normal temperature and normal humidity (23 ° C./60% R
H), 1.65 under low temperature and low humidity (15 ° C./10% RH), and 1.61 under high temperature and high humidity (32.5 ° C./90% RH). Obtained. or,
The halftone reproducibility was good in various environments. At this time, the charge amount of the toner was measured to be −19.6 μc / g under normal temperature and normal humidity, −20.0 μc / g under low temperature and low humidity, and −19.1 μc under high temperature and high humidity.
/ G and was substantially independent of environmental changes and was stable. Further, using this developer, a copy durability test of 30,000 sheets was conducted under normal temperature and normal humidity, and even after 30,000 sheets, the image reflection density was sufficiently high at 1.65, and roughness of the halftone portion was observed. And a clear image was obtained. As a result of observation of the developer after the endurance with an electron microscope, the surface of the carrier was free of spent toner and the coating state of the coating resin was good.

Example 6 Polyester resin obtained by condensation of propoxylated bisphenol and fumaric acid 100 parts Phthalocyanine pigment 5 parts Chromium complex salt of di-tert-butylsalicylic acid 4 parts The above formulations were sufficiently mixed with a Henschel mixer. 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 by a Henschel mixer to prepare a cyan toner having silica fine powder on the surface of toner particles.

Example 1 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.

[0183]

[Table 2]

[0184]

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) Toner deterioration prevention (4) Developability (5) Prevention of Carrier Adhesion on Photoconductor (6) Control of Carrier Resistance (7) Stable Charging of Toner during Running and Humidity Fluctuation Can Be Satisfactorily Satisfied and 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

Continuation of the front page (72) Inventor Yukihiro Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takeshi Ikeda 3- 30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-1-118150 (JP, A) JP-A-3-217857 (JP, A) JP-A-4-34441 (JP, A) (58) Fields investigated (Int. ^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. Has a graft-modified 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 graft-modified alkoxyalkylated polyamide 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 surface of the core material has a graft-modified alkoxyalkylated polyamide resin. A method for producing a magnetic material-dispersed 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 the image forming method for developing a latent image formed on a photoreceptor by applying a bias voltage in a development area with a system developer, a resin coating the surface of the core material has a graft-modified alkoxyalkylated polyamide resin. An image forming method comprising: