JP3114033B2 - Magnetic material-dispersed carrier, two-component developer for electrostatic image development, and method for producing magnetic material-dispersed carrier - 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.

[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.

In general, carriers constituting such a two-component developer are roughly classified into conductive carriers and insulating carriers. There are various characteristics required for these carriers, but particularly important characteristics include appropriate chargeability, pressure resistance to an applied electric field, impact resistance, abrasion resistance, spent resistance, developability, and productivity. Can be

On the other hand, when the developer whose true specific gravity increases becomes a predetermined layer thickness on the sleeve by the developer layer thickness regulating member, the burden on the developer increases. (A) The above-mentioned toner filming (b) Carrier destruction (c) Deterioration of the toner is apt to occur, and as a result, the deterioration of the developer and the accompanying image quality deterioration of the developed image are liable to occur.

Further, when the particle size of the carrier increases, the load on the developer increases similarly to the above, so that the above-mentioned (a) to (c) easily occur, and as a result, the deterioration of the developer occurs. It will be easier. Also, if the carrier particle size is large,
(D) It is well known that the fine line reproducibility of a developed image is poor, that is, the developability is poor.

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.

As the magnetic fine particles to be dispersed in the core material, hard ferrite can be used as disclosed in JP-A-59-501840.

However, if the magnetic substance-dispersed small particle size carrier does not contain a large amount of magnetic substance in the carrier particles, the magnetic properties of the carrier are not sufficient, and the carrier adheres to the photoreceptor during development. Will occur,
Alternatively, there is a problem that the transportability of the developer on the developing sleeve is not sufficient. Therefore, in the magnetic material-dispersed small particle size carrier, it is important to incorporate a large amount of the magnetic material. At this time, the impact resistance is weak because the amount of the magnetic material increases with respect to the binder resin. When the developer has a predetermined layer thickness on the sleeve with the developer layer thickness regulating member, the magnetic material is easily dropped from the carrier, and as a result, the developer is easily deteriorated. Even in this case, there is a drawback that it cannot be drastic as a measure for extending the life of the developer.

In addition, when the magnetic material is contained in a large amount in the magnetic material-dispersed small particle size carrier, the specific resistance of the carrier decreases due to an increase in the amount of the magnetic material having a low specific resistance. In addition, there is a disadvantage that image defects due to a bias voltage applied during development are likely to occur.

To cope with this, it is possible to cope with the technique disclosed in Japanese Patent Application Laid-Open No. 58-21750, in which the carrier is coated with a resin. According to the carrier coated with the above resin, spent resistance, impact resistance,
The withstand voltage with respect to the 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, 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 leakage of the 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.

Therefore, in consideration of the above-mentioned required characteristics of the carrier, the conventionally used carrier still has a problem to be improved, and a carrier with further improvement is desired.

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) Stabilization of toner chargeability (longer life in chargeability) ( 8) Stabilization of toner chargeability against environmental fluctuations (9) It is desired to further improve the density of the magnetic brush for obtaining a high-definition image.

[0019]

SUMMARY OF THE INVENTION The main object of the present invention is to:
This solves the problem of the magnetic material-dispersed carrier whose surface is coated with a resin as described above. As a result, it is not necessary to replenish the carrier at the time of running, and at the time of running, when the toner fluctuates when the humidity fluctuates. An object of the present invention is to provide a magnetic material-dispersed carrier excellent in developability and developer life by stabilizing chargeability.

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. An object of the present invention is to provide a magnetic material-dispersed carrier having improved stability by the characteristics of a resin to be coated and excellent in developability and developer life.

It is a further object of the present invention to provide a magnetic material-dispersed carrier having an appropriate resistance and having little current leakage or adhesion of the carrier to a photosensitive member even when a bias voltage is applied. Things.

Another object of the present invention is to provide a magnetic material-dispersed carrier capable of reducing the share of the toner, suppressing toner deterioration, and stably providing high image quality for a long period of time.

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 a two-component developer for developing an electrostatic charge image which has a high density of "spikes" of a magnetic brush per unit area on a sleeve and can obtain a high-definition image. Things.

[0025]

The present invention has a core material in which magnetic fine particles are dispersed in a binder resin,
In a magnetic material-dispersed carrier obtained by coating the surface of the core material with a resin, the magnetic fine particles include strontium ferrite, barium ferrite, or lead ferrite, and the ferrite is used as other components in the periodic table IA,
IIA, IIIA, IVA, VA, VIA, IB, II
B, IVB, VB, VIB, VIIB, and VIII elements may be contained, the content of other elements is less than 1 wt%, and the coercive force of the magnetic fine particles is 300 Gauss or more under a magnetic field of 10 K Oersted. The resin for coating the surface of the core material has a styrene-acrylic copolymer, the monomer ratio of the acrylic component in the copolymer is 30 to 90% by weight, and the weight average molecular weight of the copolymer Is 30,000 to 70000, and the weight average molecular weight /
A magnetic material-dispersed carrier having a number average molecular weight of 3.0 to 5.0.

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

The carrier of the present invention improves the drawbacks of the conventional resin-coated magnetic material-dispersed carrier, and is excellent in impact resistance, electric resistance, and stability of charging the toner over a long period of time. , The carrier of the present invention is developable,
The reason why the developer life is remarkably excellent and a high-definition image can be obtained is not clear, but is considered to be due to the following reasons.

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

That is, when the surface of the carrier is divided into minute portions, if the coating is uniform, the impact resistance, the resistance value, and the charging property to the toner have the same characteristics in any portion. It is considered to show.

Further, the present inventors use a specific magnetic material for the magnetic fine particles constituting the carrier core material, so that the carrier has a specific resistance value, magnetic characteristics, and the like. It is speculated that leakage and carrier adhesion are prevented, and that the developer forms a dense magnetic brush, thereby obtaining a high-definition image.

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

The styrene-acrylic copolymer which can be used as the coating resin of the carrier core material of the present invention includes a copolymer of a styrene derivative and an acrylate and a copolymer of a styrene derivative and a methacrylate. Refers to a polymer. The following compounds can be mentioned as specific examples of the monomers constituting these styrene-acrylic copolymers. That is, as the styrene derivative, styrene, o-methylstyrene, m-methylstyrene, p
-Methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, p -N-
Nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, p-nitrostyrene, etc. Is mentioned.

The acrylates include, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate,
Examples thereof include 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate.

Examples of the methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and the like.
Isobutyl methacrylate, n-octyl methacrylate,
Examples include dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

In the present invention, the monomer ratio of the acrylic component in the styrene-acryl copolymer as the coating resin is preferably 30 to 90% by weight. 30% by weight
If it is less than 1, the coating uniformity contributing to the present invention cannot be obtained, and the charge stability of the toner is lacking. 90% by weight
If it is larger, uniform coverage can be obtained, but the strength against impact resistance is insufficient.

Further, the weight average molecular weight of the copolymer which can be used for the coating resin of the carrier core material of the present invention is essential to be 30,000 to 70000, and the weight average molecular weight / number average molecular weight is 3.0. It is essential that it be ~ 5.0. If the weight-average molecular weight is less than 30,000, the strength with respect to the impact resistance of the carrier cannot be obtained, and
If it is more than 000, the coatability of the carrier core becomes poor, and the strength of the carrier and the charge stability are lacking. More importantly, at this time, even if the weight average molecular weight falls within this range, the weight average molecular weight /
Unless the number average molecular weight is in the range of 3.0 to 5.0, the effects of the present invention cannot be obtained. If the weight average molecular weight / number average molecular weight is less than 3.0, the coating resin is uniformly coated, but the impact resistance is poor. If the weight-average molecular weight / number-average molecular weight is more than 5.0, the uniformity of the coating on the carrier core is deteriorated, and the carrier strength and the desired charge stability cannot be obtained.

In the present invention, the molecular weight and molecular weight distribution of the coating resin which can be used as the coating resin for the carrier core material, and the molecular weight of the fluorine-containing resin are determined by GPC (gel permeation chromatography). It refers to the value determined in light of a calibration curve obtained using polystyrene. The measurement conditions are shown below.

Apparatus: GPC-150C (Waters) Column: 7 columns of Shodex KF (Showa Denko) Temperature: 40 ° C. Solvent: THF (tetrahydrofuran) Flow rate: 1.0 ml / min Sample: 0. Injecting 0.4 ml of a 15% sample In the present invention, examples of the resin used as the binder resin constituting the carrier core material include all resins obtained by polymerizing vinyl monomers. Examples of the vinyl monomer 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,
a styrene derivative such as p-nitrostyrene, ethylene,
Ethylene and unsaturated monoolefins such as propylene, butylene and isobutylene; unsaturated diolefins such as butadiene and isoprene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl acetate and propion Vinyl esters such as vinyl acrylate and vinyl benzoate; methacrylic acid and methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid- Α-methylene aliphatic monocarboxylic esters such as 2-ethylhexyl, stearyl methacrylate and phenyl methacrylate; acrylic acid and methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate Acrylic esters such as propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate; maleic acid, maleic acid half ester; vinyl methyl Vinyl ethers such as 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 must contain at least one of Sr ferrite, Ba ferrite, and Pb ferrite. Law table IA, IIA, IIIA, IVA, VA, VIA,
IB, IIB, IVB, VB, VIB, VIIB, VI
Although a group II element may be included, other elements are preferably less than 1 wt%.

As described above, this is important in order to control the resistance of the core material to an optimum value and to increase the density of the "spikes" of the magnetic brush on the sleeve and prevent carrier adhesion.

For the same reason, the magnetic field of the carrier of the present invention 1
The coercive force at 0K Oersted is 300 Gauss or more, preferably 500 Gauss or more. The magnetic force at a magnetic field of 1K Oersted is 5 emu / g or more.
59 emu / g is preferable, and 10 emu / g is more preferable.
/ G to 19 emu / g.

The magnetic properties of the carrier described below are values measured by VSM manufactured by Toei Kogyo.

The magnetic fine particles preferably have a primary average particle diameter of 2.0 μm or less. When it is larger than 2.0 μm, the surface of the core material is not dense, and uniform coating cannot be performed. Furthermore, the specific resistance of the magnetic fine particles according to the present invention must be 10 ⁷ Ω · cm or more, and the content with respect to the total amount of the carrier must be 30% by weight or more, preferably 50% by weight or more. If it is less than 30% by weight, desired magnetic properties cannot be obtained.

The average particle diameter of the carrier particles of the present invention (hereinafter, referred to as
It is preferable to use “carrier particle size” in the range of 10 to 60 μm. When the carrier particle size is less than 10 μm, the carrier tends to easily adhere to the photoconductor,
On the other hand, if it exceeds 60 μm, the share of the developer in the developing device becomes large, and the deterioration of the developer, in particular, the detachment of the external additive of the toner particles and the change in shape tend to be caused. Furthermore, when the particle size is large, the specific surface area is small, so that the amount of toner that can be retained when constituting the developer is small, and an image lacking in definition is obtained. In the present invention, the particle size of the carrier is indicated by the maximum chord length in the horizontal direction, and the measuring method is randomly selected from 500 or more carriers by a microscope, and the particle size of each carrier is obtained by actually measuring the diameter. The average value of the carrier particle sizes was defined as the carrier particle size of the present invention.

The true specific gravity of the carrier of the present invention is 1.5 to 5.
A range of 0 is preferred. More preferably, 1.5 to 4.5.
It is. If the true specific gravity exceeds 5.0, the load on the developer in the developing device increases, which is not preferable from the viewpoint of deterioration of the developer. If the true specific gravity is less than 1.5, it is practically impossible to obtain desired magnetic characteristics. The true specific gravity of the carrier used in the present invention was a Trudencer (manufactured by Seishin Enterprise).

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

The specific resistance of the carrier of the present invention is shown in FIG.
Was measured using the cell shown in FIG. That is, the cell A was filled with a carrier, the electrodes 1 and 2 were arranged so as to be in contact with the filled carrier, a voltage was applied between the electrodes, and the current flowing at that time was measured to determine the specific resistance. The measurement condition is that the contact area S of the filled carrier with the cell is about 2.3 cm.
^{2. The} thickness d is about 1 mm, the load on the upper electrode is 275 g, and the applied voltage is 100 V. Here, since the carrier is a powder, the specific resistance may change depending on the filling rate, and thus care must be taken.

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 for manufacturing a core material, the binder resin and the magnetic fine particles are mixed at a desired ratio, and an appropriate melt-mixing device such as a three-roll mill or an extruder is used. Kneading at a temperature, cooling, and then pulverizing and classifying, or by dissolving the binder resin in a soluble solvent, mixing the magnetic fine particles into a slurry, and manufacturing using a spray drier. Granules, a method of drying, or adding magnetic fine particles, a polymerization initiator, a suspension stabilizer, etc. to a monomer solution of a binder resin for a core material,
There is a suspension polymerization method of granulating and polymerizing after dispersing. In particular, according to the polymerization method, it is easy to control the sphericity to 2 or less, so that it is a more preferable method for producing a 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. In addition,
The amount of the coating resin varies depending on the true specific gravity of the core material. When the true specific gravity of the carrier is set to X, the optimum value of the amount of the coating resin needs to satisfy the following relational expression.

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

That is, if the amount of the coating resin is less than 1 / 2X% by weight, it is difficult to uniformly coat the surface of the core material because the amount of the coating resin is small. Does not hold. On the other hand, if it exceeds 50 / X% by weight, it becomes difficult to coat uniformly because the amount of coating resin is too large. Further, there is a tendency that the developing property is deteriorated due to the adhesion of the excess coating resin in the developer to the photoreceptor.

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

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

Further, 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 structure 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 to 50% 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 in the range of 8 to 12.7 μm
As described above, 1 to 30% by number, preferably 1 to 23% by number
And more preferably 8 to 20% by number. When the content is more than 23% by number, particularly when the content exceeds 30% by number, the image quality is deteriorated, and the development more than necessary (that is, the excessive amount of toner) 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. When the number% (N%) and the volume% (V%) of the toner particle group having a particle diameter of 5 μm or less, N / V = −
There is a relationship of 0.04N + k, which indicates a positive number in the range of 4.5 ≦ k ≦ 6.5. Preferably, 4.5 ≦ k ≦ 6.0, and 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 viewpoint, 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 amount of 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 polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-
Vinyl naphthalene copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Copolymers: polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, cumarone indene resin, and petroleum resin.

In the heat and pressure roller fixing method in which almost no oil is applied, the offset phenomenon in which a part of the toner image on the toner image support member is transferred to the roller and the adhesion of the toner to the toner image support member are important. It is a problem.
These problems must be taken into account at the same time because toners that fix with less heat energy tend to block or cake during storage or in a developer. Therefore, in the present invention, when using the heating / pressing roller fixing method in which almost no oil is applied, the selection of the binder resin is more important. Preferred binder resins include crosslinked styrenic copolymers and crosslinked polyesters.

Examples of comonomers 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.

The toner according to the present invention has charge controllability 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

[0077]

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, an organometallic complex and a chelate compound are effective. Examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate, and 3,5-acetylacetonate. 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).

When internally added to the toner, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (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 size of 10 μm or less, the specific surface area is larger than that of a toner having a volume average particle size 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 powders manufactured 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.

The silica fine powder used herein may be a silicate such as anhydrous silicon dioxide (colloidal silica); aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate.

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

When the toner according to the present invention is used as a positively chargeable toner, the silica fine powder added to prevent wear of the toner and to prevent 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 a 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.

[0092]

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.

[0095]

Embedded image

The following are examples of the saturated heterocyclic group.

[0097]

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

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

The silica fine powder used in the present invention may be treated with a silane coupling agent or a treating agent such as an organosilicon compound for the purpose of imparting 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 critical area 5
Fine titanium oxide powder (TiO ₂ ) of 0 to 400 m ² / g may be used. Further, a mixed powder of silica fine powder and titanium oxide fine powder may be used.

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

As the coloring agent, conventionally known dyes and / or pigments can be used. For example, carbon black, phthalocyanine blue, peacock blue,
Permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like can be used. The content is 0.1 to 20 parts by weight, preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the binder resin.
It is preferably at most 2 parts by weight, more preferably 0.5 to 9 parts by weight.
Good by weight.

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

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

To prepare the toner according to the present invention, a vinyl-based or non-vinyl-based thermoplastic resin, if necessary, a pigment or dye as a colorant, a charge control agent, and other additives are mixed with a mixer such as a ball mill. After thoroughly mixing, using a hot kneader such as a heating roll, kneader, or extruder, disperse or disperse the pigment or dye in the resin mixed with each other by melting, kneading, and kneading, and cooling. After singulation, toner particles can be obtained by crushing and strict classification. The toner particles can be used as a toner as it is, but if necessary, an external additive such as silica fine powder is added to the obtained toner particles, and the toner particles and the external additive are mixed using a mixer such as a Henschel mixer. By mixing the above, a toner can be obtained.

[0108]

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. Incidentally, all percentages and parts in the following formulations indicate% by weight and parts by weight,
Mw indicates a weight average molecular weight, and Mn indicates a number average molecular weight.

(Example 1) Styrene 10.0% Isobutyl acrylate 5.0% Sr ferrite particles 85.0% (mol% Fe ₂ O ₃ : SrO = 85: 15) The above material was placed in a container at a temperature of 70 ° C. And dissolved to obtain 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 (core material).

The surface of the obtained core material was coated with the following resin coating layer.

Styrene-2-ethylhexyl methacrylate (45/55) Mw / Mn = 3.0, Mw = 40000 The above styrene-based copolymer was coated such that the amount of resin coated was 0.8% from the above formula. 10% was dissolved in toluene to prepare a carrier coating solution. The carrier coating solution was applied to the above-mentioned core material while being applied and dried by an applicator (a Spira coater manufactured by Okada Seiko Co., Ltd.). The obtained coated magnetic substance-dispersed resin carrier is dried at a temperature of 40 ° C. for 1 hour to remove the solvent, and then heated at a temperature of 110 ° C. for 2 hours to cover the core material surface with a resin coating layer. A mold resin carrier was obtained. Observation of the obtained resin-coated magnetic substance dispersed resin carrier by an electron microscope confirmed that the core material was uniformly coated with the resin. Table 1 shows the physical properties of the carrier.

On the other hand, 100 parts of a propoxylated bisphenol and fumaric acid are condensed to obtain 100 parts of a polyester resin. Phthalocyanine pigment is 5 parts. Chromium complex salt of di-tert-butylsalicylic acid is 4 parts. 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 8.2 μm.
I got

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

This cyan toner and the above resin carrier were mixed in a temperature / humidity environment of N / N (23 ° C./60% RH) so as to have a toner concentration of 5% to obtain a developer. 100 g of the obtained developer was put in a 250 cc plastic bottle, and shaken with a Turbula mixer for 1 hour. Thereafter, the developer was taken out, and the developer was observed with an electron microscope. As a result, no detachment of the magnetic material from the carrier, no peeling of the coating material, and no filming by the toner were observed. Also, no detachment or burial of the external additive of the toner was observed.

Next, the carrier and the cyan toner were mixed in an N / N environment at a toner concentration of 5% to prepare a developer, and a full color leather copying machine CLC-500 (Canon Inc.) having a development contrast fixed at 350 V was used. Using a remodeled machine manufactured by the Company). The above results show that, as shown in Table 2, excellent durability, no carrier adhesion on the photoreceptor was observed, and the developer was dense, and higher image quality was achieved as compared with the conventional one. ing.

A developer was obtained by mixing the cyan toner and the above-mentioned resin carrier under a temperature / humidity environment of L / L (15 ° C./10% RH) to a toner concentration of 5%. Under the same environment, the full color laser copier CLC-
It was placed in a modified developing device for 500, and idling was performed for 30 minutes by driving an external motor (peripheral speed: 300 rpm). Thereafter, using a CLC-500 remodeling machine, a developing contrast of 3
An image was displayed at 50 V. As a result, the density of the solid image was sufficient, and the reproducibility of the halftone portion was also good.

Comparative Example 1 The magnetic material-dispersed resin particles used in Example 1 were used as carriers without being coated with a resin.

Table 1 shows the physical properties of this carrier. Also,
This carrier was subjected to the same test as in Example 1.

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

Comparative Example 2 The coating resin used in Example 1 was coated in the same manner as in Example 1 except that 46 μm reduced iron particles were used instead of the magnetic material-dispersed resin particles used in Example 1.
Table 1 shows the physical properties of the obtained carrier. The same measurement or test as in Example 1 was performed using this carrier.

As a result of the shaking test, the carrier was not changed from that before shaking, but a slight burial of the external additive on the toner surface was observed. Further, the ears of the developer were coarse, and as a result of an image display test, a slight roughness was observed particularly in a halftone portion.
As a result of the durability test of 10,000 sheets, line images were disturbed.

Comparative Example 3 The core material used in Example 1 was replaced with 2-ethylhexyl styrene-methacrylate (50/5) instead of the carrier coating solution used in Example 1.
0) Using Mw / Mn = 21.3, Mw = 120,000, 10% was dissolved in toluene so that the coating resin amount was 0.8% to prepare a carrier coating solution.

The carrier coating solution was applied in the same manner as in Example 1 to obtain a carrier in which the surface of the carrier core material was coated with a resin coating layer. Table 1 shows the physical properties of this carrier. When the obtained resin carrier was observed with an electron microscope, the coated state was not uniform. A test similar to that of Example 1 was performed using this carrier.

As a result of the shaking test, peeling of the coating material was observed, and slight detachment of the magnetic material was also observed. further,
As a result of the image display test, image unevenness occurred.

Comparative Example 4 Styrene 10.0% Isobutyl acrylate 5.0% Cu—Zn ferrite particles 85.0% (mol% Fe ₂ O ₃ : CuO: ZnO = 70: 20: 10) Was granulated in the same manner as in Example 1 to obtain magnetic material-dispersed resin particles. The surface of the obtained particles was coated with the same resin coating layer as in Example 1. According to observation with an electron microscope,
It was confirmed that the core material was uniformly coated with the resin. Table 1 shows the physical properties of this carrier.

Further, the same cyan toner as in Example 1 and the above carrier were mixed in the same manner as in Example 1, and a test was carried out. As a result, the ears of the developer were coarse and coarseness was observed in the image. Further, carrier adhesion to the photoreceptor was observed.

Example 2 Using the same formulation as in Example 1, the mixture was heated to a temperature of 70 ° C. in a container and dissolved to obtain a monomer mixture. While maintaining the temperature at 70 ° C., the initiator azobisisonitrile was added and dissolved to prepare a monomer composition. This was charged into a 2 liter flask containing 1.2 liter of a 1% PVA aqueous solution, and stirred at 70 ° C. with a homogenizer at 2400 rpm for 10 minutes to granulate the composition. Then, while stirring with a paddle stirrer, 70 ° C, 10
Polymerization was carried out for 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 particle diameter of the obtained magnetic substance-dispersed resin particles was 75 μm. The surface of the magnetic material-dispersed resin particles was coated in the same manner as in Example 1 to obtain a carrier. Table 1 shows the physical properties of this carrier. A test similar to that of Example 1 was performed using this carrier.

As a result of an image display test after idling under low humidity, slight roughness was observed particularly in the halftone portion, but this did not cause any practical problem.

Example 3 Styrene-2-ethylhexyl acrylate 25% -butyl acrylate copolymer (monomer composition ratio = 80: 5: 15) Ba-ferrite 75% (mol% Fe ₂ O ₃ : BaO = 85:15) The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded at least twice with a three-roll mill, cooled, and coarsely ground to a particle size of about 2 mm using a hammer mill. Next, it was pulverized to a particle size of about 53 μm by a pulverizer using an air jet method. Further, the obtained finely pulverized product was put into a Mechanomill MM-10 (manufactured by Okada Seiko Co., Ltd.) and mechanically sphericalized. The spheroidized finely pulverized particles were further classified to obtain magnetic substance-dispersed resin particles. The particle size of the obtained magnetic material-dispersed resin particles was 50 μm.

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

Table 1 shows the physical properties of this carrier. When a test similar to that of Example 1 was performed on this carrier, good results were obtained as in Example 1.

Example 4 Resin fine particles were prepared in the same manner as in Example 1, and a styrene-propyl acrylate copolymer (40/60) Mw / Mn = 5.0, Mw = 50,000 and a coating resin amount of 1 1.0% in toluene.
The above resin fine particles were coated in the same manner as in Example 1 using a carrier coating solution in which the carrier solution was dissolved in% to obtain a magnetic material-dispersed resin carrier. In addition, when a test similar to that in Example 1 was performed, good results were obtained as in Example 1.

Example 5 Magnetic material-dispersed resin particles were produced in the same manner as in Example 3 except that the amount of Ba-ferrite was changed to 35% (the remainder was polyester resin). This was coated in the same manner as in Example 3 using the coating resin used in Example 4 to obtain a magnetic material-dispersed resin carrier. Table 1 shows the physical properties of this carrier. This carrier was used in Example 1
The test was performed as in. The results of the shaking test were as good as in Example 3. However, some carrier adhesion on the photosensitive drum was observed. Although it was slightly lower than that, it was not a problem in practical use.

(Example 6) Phenol 10.0% Formaldehyde 5.0% (Formaldehyde about 37%, Methanol about 10%, balance water) Sr ferrite 85.0% (Fe ₂ O ₃ : SrO = 85: 15) (Mole ratio) Using ammonia as a basic catalyst and calcium fluoride as a polymerization stabilizer, the above materials were gradually heated to a temperature of 80 ° C while stirring in an aqueous phase, and polymerization was performed for 2 hours. The particle size of the obtained core material was 40 μm. These resin particles were coated with the coating resin used in Example 3 by a coating resin amount of 1.1.
%, And coating was performed in the same manner as in Example 3 using a toluene solution in which 10% was dissolved. When a test similar to that in Example 1 was performed using this carrier, good results similar to those in Example 1 were obtained.

Example 7 Polyester resin obtained by condensing 100 parts of propoxylated bisphenol and fumaric acid 5 parts Phthalocyanine pigment 5 parts Chromium complex salt of di-tert-butylsalicylic acid 4 parts Pre-mixed, melt-kneaded at least twice with a three-roll mill, cooled, coarsely pulverized with a cutter mill, and finely pulverized with a fine pulverizer using a jet stream, and the obtained finely pulverized powder is obtained. The powder was classified by a fixed-wall air classifier to produce a classified powder. In addition, the obtained classified powder is multi-divided using the Coanda effect (Nippon Mining Co., Ltd. elbow jet classifier)
Then, the ultrafine powder and the coarse powder were strictly classified and removed at the same time to obtain a cyan powder (toner) having a weight average particle diameter of 6.0 μm.
Table 3 shows the particle size distribution of this toner.

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

A test was conducted in the same manner as in Example 1 except that the cyan toner obtained as described above was used instead of the toner used in Example 1. As a result, the same results as in Example 1 were obtained. The image performance and the toner consumption were even better than in Example 1.

[0138]

[Table 1]

[0139]

[Table 2]

[0140]

[Table 3]

[0141]

As described above, when a magnetic carrier coated with the coating resin used in the present invention and having specific magnetic characteristics is used, (1) the "spring" of the carrier on the sleeve is increased, and A fine image can be obtained. (2) Spent resistance (3) Impact resistance (prevention of carrier destruction) (4) Prevention of toner deterioration (5) Developability (6) Prevention of carrier adhesion on photoreceptor (7) Charging property of toner Can be sufficiently satisfied, and a high-quality image 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.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-1966052 (JP, A) JP-A-4-866749 (JP, A) JP-A-2-108065 (JP, A) 501840 (JP, A)

Claims (15)

(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, wherein the magnetic fine particles are strontium ferrite. , Barium ferrite, or lead ferrite, which is contained as another component in the periodic table IA, IIA, III.
A, IVA, VA, VIA, IB, IIB, IVB, V
B, VIB, VIIB, and VIII elements may be contained, the content of other elements is less than 1 wt%, and the coercive force of the magnetic fine particles is 30% under a magnetic field of 10 K Oersted.
0 Gauss or more, the resin coating the surface of the core material has a styrene-acrylic copolymer, and a monomer ratio of an acrylic component in the copolymer is 30 to 90% by weight; weight average molecular weight of 3 from 0,000 to 70,000, a weight average molecular weight / number average molecular weight of 3.0-5.0, magnetic material-dispersed carrier, characterized in that. 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 carrier has an average particle size of 10 μm to 60 μm.
3. The magnetic material-dispersed carrier according to claim 1, wherein m is m. 4. A carrier having a specific resistance of 10 ⁸ Ω · cm to 1
4. The magnetic material-dispersed carrier according to claim 1, wherein the carrier is 0 ¹³ Ω · cm. 5. The magnetic material dispersion according to claim 1, wherein the core material obtained by dispersing the magnetic fine particles in the binder resin is produced by a polymerization method. Mold carrier. 6. An electrostatic image developing method comprising: a magnetic material-dispersed carrier having a core material in which magnetic fine particles are dispersed in a binder resin, the core material surface being coated with a resin; and a toner. In the two-component type developer, the magnetic fine particles contain strontium ferrite, barium ferrite, or lead ferrite, and the ferrite is used as another component in the periodic tables IA, IIA, and III.
A, IVA, VA, VIA, IB, IIB, IVB, V
B, VIB, VIIB, and VIII elements may be contained, the content of other elements is less than 1 wt%, and the coercive force of the magnetic fine particles is 30% under a magnetic field of 10 K Oersted.
0 Gauss or more, the resin coating the surface of the core material has a styrene-acrylic copolymer, and a monomer ratio of an acrylic component in the copolymer is 30 to 90% by weight; weight average molecular weight of 3 from 0,000 to 70,000, a weight average molecular weight / number average molecular weight of 3.0-5.0, a two-component developer for developing electrostatic images, characterized in that. 7. The true specific gravity of the carrier is 1.5 to 5.0.
7. The electrostatic image developing device according to claim 6, wherein
Component developer. 8. The carrier has an average particle size of 10 μm to 60 μm.
m. The electrostatic charge according to claim 6, wherein
Two-component developer for image development. 9. The carrier having a specific resistance of 10 ⁸ Ωcm-1
0 ¹³ 9. The method according to claim 6, wherein the resistance is Ω · cm.
The two-component developer for developing an electrostatic image according to any one of the above. 10. A method in which magnetic fine particles are dispersed in a binder resin.
Core material is produced by a polymerization method
The static electricity according to any one of claims 6 to 9, wherein
Two-component developer for charge image development. 11. 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 carrier coating solution comprises a resin material and a solvent for dispersing or dissolving the resin material, wherein the magnetic fine particles include strontium ferrite, barium ferrite, or lead ferrite, and the ferrite is , And other components of the periodic table IA, IIA, III
A, IVA, VA, VIA, IB, IIB, IVB, V
B, VIB, VIIB, and VIII elements may be contained, the content of other elements is less than 1 wt%, and the coercive force of the magnetic fine particles is 30% under a magnetic field of 10 K Oersted.
0 Gauss or more, wherein the resin material covering the surface of the core material has a styrene-acrylic copolymer, and a monomer ratio of an acrylic component in the copolymer is 30 to 90% by weight; Has a weight average molecular weight of 30000 to 70000,
A weight-average molecular weight / number- average molecular weight of 3.0 to 5.0 , a method for producing a magnetic substance-dispersed carrier. 12. The true specific gravity of the carrier is 1.5 to 5.0.
The magnetic substance dispersion type according to claim 11, wherein
Carrier manufacturing method. 13. The carrier has an average particle size of 10 μm to 60 μm.
The particle size is μm.
A method for producing a magnetic material dispersed type carrier. 14. The carrier having a specific resistance of 10 ⁸ Ω · cm ~
10 ¹³ Ω · cm.
13. A method for producing the magnetic substance-dispersed carrier according to any one of the above items 13.
Law. 15. A magnetic fine particle dispersed in a binder resin.
Core material is produced by a polymerization method
The method according to any one of claims 11 to 14, wherein
A method for producing a magnetic material dispersed type carrier.