JPH10104879A - Electrostatic charge image developer and developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the spending of a carrier, to attain satisfactory kick-off of electrostatic charge and to ensure high durability by coating the surfaces of the core particles of the carrier with a cyclic acrylic ester polymer. SOLUTION: This electrostatic charge image developer consists essentially of a toner having 3-9μm volume average particle diameter and >=5m<2> /g BET specific surface area and a carrier obtd. by coating the surfaces of core particles with a cyclic acrylic ester polymer and/or a cyclic methacrylic ester polymer. In the case of a toner of a small particle diameter, the electrostatic chargeability is improved by increasing the specific surface area of the toner itself because kick-off of electrostatic charge is not sufficient. Such a toner is liable to stick to a carrier and the durability deteriorates. In order to prevent this deterioration, a refreshed surface is always kept by using a resin having high peelability as a carrier coating resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a two-component electrostatic image developer used for forming an image in a copying machine, a printer or the like, and a developing method using the same.

[0002]

2. Description of the Related Art Conventionally, high-quality image forming apparatuses include:
Mostly, an electrostatic image developing method such as an electrophotographic method is used.
Therefore, there is a high demand for an improvement in image quality in the electrostatic image development method, and in particular, an improvement in performance when used as a color copier for output of a computer or a word processor.

[0003] One of the specific trends is to improve electrostatic image developers in order to improve resolution and sharpness, and in particular, to reduce the particle size of toners for electrostatic image development. .

For example, JP-A-2-282755, JP-A-3-282755
No.-64763, the volume average particle size is 6 to 1
In 0 μm toner, 15 to 40% by number of toner particles of 5.04 μm or less, 0.1 to 5.0% by volume for 12.7 to 16.0 μm, and 1.0 volume for toner of 16.0 μm or more. % Or less, the volume average particle diameter in all the toner particles.
There is disclosed a toner for developing an electrostatic image in which a toner having a particle diameter of 35 to 10.1 μm is within a certain range.

Japanese Patent Application Laid-Open No. 2-282756 discloses a toner for developing an electrostatic charge image having a volume average particle diameter of 4 to 10 μm and having the same definition as described above. JP-A-6-118885 and JP-A-6-289648 disclose 20 to 40% by number of particles having a particle size of 2.0 to 4.0 μm, and 4.0 to 4.0%.
A toner having a particle size of about 8.0 μm or more and 60% by number or more and a triboelectric charge amount with iron powder of 30 μC / g or more is disclosed. Further, JP-A-6-75430 discloses that the volume average particle size is 3
In the case of toner having a size of from 7 to 7 μm, those having a size of 5.04 μm or less are 40% by volume or more, those having a size of 4.0 μm or less are 10 to 70% by volume, and those having a size of 8.0 μm or more are 2 to 20% by volume.
There is disclosed a toner in which the content of the toner having a size of 08 μm or more is 6% by volume or less.

As a developer used in the electrophotographic method, a dry magnetic two-component developer comprising a toner and a magnetic carrier is generally used. The toner development mechanism using a dry magnetic two-component developer generates a charge of the opposite polarity to the latent image in the toner due to the frictional charging of the toner and the carrier, and develops and transfers the toner to the latent image portion on the photoreceptor to visualize the image. It is a mechanism to make it.

The characteristics required for the carrier are impact resistance,
A wide variety of properties such as wear resistance, developability, charge control, and spent resistance. In order to maintain high image quality and high performance for a long period of time, it is particularly important to reduce the impact force applied to the developer itself consisting of the toner and the carrier. By reducing the impact, it is possible to control the destruction and abrasion of the carrier itself and to reduce the stress on the toner, thereby suppressing the burying of the external additive on the toner surface and the progress of spent.

One of effective means for alleviating the impact is to reduce the specific gravity of the carrier, and a binder-type carrier in which magnetic fine particles are dispersed in a binder resin has been proposed and put into practical use (Japanese Patent Application Laid-Open No. Sho 54-66134). etc).

However, the binder-type carrier has a problem that the adjustability of the magnetic characteristics is not sufficient due to its structure.

[0010] Small toner particles have a small heat capacity due to their small particle size, and are liable to be buried by external additives when subjected to stress, and have low durability.

In particular, in the case of a toner whose specific surface area is improved in order to improve the rise of the chargeability, the surface property changes due to the application of stress to the surface, and it is difficult to maintain the chargeability stably for a long period of time.

In the case of a developer using a toner having a small particle diameter, the toner is apt to adhere to the surface of the carrier, resulting in a decrease in durability.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-component type electrostatic image developer which can reduce the stress on the toner, does not generate spent on the carrier, has a good charging rise, and has high durability. And a developing method using the same.

[0014]

The object of the present invention is attained by adopting one of the following constitutions.

(1) In an electrostatic image developer comprising at least a toner and a carrier, the toner has a volume average particle diameter of 3 to 9 μm, a BET specific surface area of 5 m ² / g or more, and An electrostatic image developer comprising a carrier having a core particle surface coated with a cyclic acrylate polymer and / or a cyclic methacrylate polymer.

(2) The electrostatic image developer according to (1), wherein the core is a ferrite containing an alkali metal and / or an alkaline earth metal.

(3) The electrostatic image developer according to (1), wherein the nucleus is magnetite.

(4) In a developing method for developing an electrostatic latent image formed on an electrophotographic photosensitive member with a two-component electrostatic image developer comprising at least a toner and a carrier, the toner has a volume average particle size. Is 3 to 9 μm and BE
Two-component electrostatic image development comprising a carrier having a T specific surface area of 5 m ² / g or more and a core material of the carrier coated with a cyclic acrylate polymer and / or a cyclic methacrylate polymer. A developing method characterized by using an agent.

As described above, the small particle size toner has a problem that the chargeability is insufficiently increased. For this reason, during intensive studies, focusing on the surface properties of the toner itself,
The aim was to improve the chargeability by increasing the specific surface area.

On the other hand, when a toner having a small particle diameter is used, a so-called Van der Waals force greatly contributes to increase the adhesion to a carrier, and further, the heat capacity is reduced due to the small particle diameter. ing. As a result, the toner is more likely to adhere to the carrier due to the influence of the stress on the developer as compared with the conventional toner.
For this reason, the inventors presumed that the durability was reduced, and that a countermeasure against it was necessary, and completed the present invention while studying.

That is, by using not only a simple resin but also a resin having a very small releasability as a resin for coating the carrier, a so-called refreshed surface property can always be maintained. It is presumed that contamination of the carrier due to adhesion could always be eliminated even when using the, and as a result, the durability could be improved.

The configuration of the present invention will be further described.

Toner used in the present invention The toner of the present invention may be the same as a commonly used toner.
Usually, it is colored particles mainly composed of a resin and a colorant, or processed particles thereof.

[0024] However, BET specific surface area of 5 m ² / g or more, preferably 5~80m ² / g, more preferably 5
４０40 m ² / g. The BET specific surface area is measured by a one-point method of the nitrogen adsorption method, and a specific measuring device is Flowsorb 2300 (Shimadzu Corporation). The toner of the present invention may contain a releasing agent or a charge control agent as a fixing property improving agent, if necessary.
Further, an external additive composed of inorganic fine particles or organic fine particles may be added. In any case, the toner of the present invention has a BE which is larger than that usually used.
It has a T specific surface area.

The toner of the present invention is prepared, for example, by subjecting a monomer to emulsion polymerization in a liquid to which an emulsion of necessary additives is added to produce fine polymer particles. Can be produced by a method of adding and the like.

The method for producing the toner of the present invention is not particularly limited as described above.
-265252 and JP-A-8-59840 are used. That is, a method of associating a plurality of fine particles composed of a resin, a colorant, and the like, in particular, after dispersing these in water using an emulsifier, infinitely dissolves in a coagulant and water having a concentration equal to or higher than the critical coagulation concentration Treat with organic solvent. Further, the toner having the BET specific surface area of the present invention can be formed by heat-fusing the formed polymer itself at a glass transition temperature or higher.

Particularly, in order to improve the specific surface area, a solvent which can be dissolved infinitely in water can be used to form a fine surface state, which is a preferable method.

Specifically, styrene, o-methylstyrene, m-styrene,
-Methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,
4-dimethylstyrene, pt-butylstyrene, p-
n-hexylstyrene, pn-octylstyrene, p
-N-nonylstyrene, pn-decylstyrene, p-
Styrene or a styrene derivative such as n-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-methacrylic acid 2- Ethylhexyl, stearyl methacrylate, lauryl methacrylate,
Methacrylate derivatives such as phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, acrylic Acrylate derivatives such as n-octyl acid, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate and phenyl acrylate, olefins such as ethylene and propylene / isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide and fluorine Vinyl chloride,
Halogen vinyls such as vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, etc. Vinyl ketones, N-vinyl carbazole, N-vinyl indole,
There are N-vinyl compounds such as N-vinylpyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. These vinyl monomers can be used alone or in combination. Further, it is more preferable to use a combination of monomers having an ionic dissociation group as monomers constituting the resin. For example, those having a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of a monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, and fumaric acid. Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl methacrylate, 3
-Chloro-2-acid phosphooxypropyl methacrylate and the like.

Further, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate,
Polyfunctional vinyls such as neopentyl glycol diacrylate can be used to form a crosslinked resin.

These monomers can be converted into a resin by using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method or the solution polymerization method.
As this oil-soluble polymerization initiator, azoisobutyronitrile, lauryl peroxide, benzoyl peroxide and the like can be used. When an emulsion polymerization method is used, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

As an excellent resin, the glass transition point is 20 to
Those having a softening point of 80 to 220 ° C are preferred. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka flow tester. Further, these resins have a number average molecular weight (Mn) of 1,000 to 10,000 as measured by gel permeation chromatography.
0, 2000-100,000 in weight average molecular weight (Mw)
0 is preferred. Further, as a molecular weight distribution, Mw
/ Mn of 1.5 to 100, particularly 1.8 to 70 is preferred.

The coagulant to be used is not particularly limited, but those selected from metal salts are preferably used. Specifically, as a monovalent metal, for example, a salt of an alkali metal such as sodium, potassium, and lithium, and as a divalent metal, for example, a salt of an alkaline earth metal such as calcium and magnesium, or a divalent metal such as manganese or copper Salt,
Examples include salts of trivalent metals such as iron and aluminum, and specific salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, inexpensive zinc, copper sulfate, magnesium sulfate, and manganese sulfate. Can be.
These may be used in combination.

It is preferable that these coagulants are added at a concentration higher than the critical coagulation concentration. The critical aggregation concentration is an index relating to the stability of the aqueous dispersion, and indicates the concentration at which aggregation occurs when a coagulant is added. This critical aggregation concentration is
It varies greatly depending on the emulsified component and the dispersant itself. For example, Seizo Okamura et al., “Polymer Chemistry 1
7, 601 (1960), edited by The Society of Polymer Science, Japan, and the like, and a detailed critical aggregation concentration can be determined.

As another method, a desired salt is added to the target particle dispersion at a different concentration, and the dispersion is added to the dispersion.
The (zeta) potential can be measured, and the salt concentration at which this value changes can be determined as the critical aggregation concentration.

The addition amount of the coagulant of the present invention may be not less than the critical coagulation concentration, but is preferably 1.2 to the critical coagulation concentration.
It is better to add it at least twice, more preferably at least 1.5 times.

The infinitely soluble solvent means a colored polymer dispersion, that is, a solvent which is infinitely soluble in water.
This solvent is selected so as not to dissolve the resin formed in the present invention. Specific examples include alcohols such as methanol, ethanol, propanol, isopropanol, t-butanol, methoxyethanol and butoxyethanol, nitriles such as acetonitrile, and ethers such as dioxane. Particularly, ethanol, propanol and isopropyl alcohol are preferred.

The amount of the solvent that can be dissolved infinitely is 1 to 300% by volume based on the polymer-containing dispersion to which the flocculant has been added.
Is preferred.

Various methods can be used as the polymerization method for forming the resin used to form the toner of the present invention, and the above-mentioned emulsion polymerization method is particularly preferable.

As the colorant used in the toner of the present invention, any of carbon black, a magnetic substance, a dye, a pigment and the like can be arbitrarily used. Examples of the carbon black include channel black, furnace black, acetylene black, thermal black, and lamp. Black or the like is used. As the dye, C.I. I. Solvent Red 1, 49, 5
2, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 8
1, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc., and mixtures thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 5
3: 1, 57: 1, 122, 139, 144,
149, 166, 177, 178, 222,
C. I. Pigment Orange 31, 43 and C.I. I. Pigment Yellow 14, 17, 17, 93, 94, 1
38, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 60 and the like, and mixtures thereof can also be used. The number average primary particle size varies depending on the type, but is preferably about 10 to 200 nm.

As a method of adding a colorant, a method of preparing the polymer itself by an emulsion polymerization method, and then adding a coagulant at the stage of coagulation to color the polymer, or a method of polymerizing a monomer is used. A method of adding a coloring agent, polymerizing, and coloring at the stage of the coloring can be used. When the colorant is added at the stage of preparing the polymer, it is preferable to use the colorant after treating the surface with a coupling agent or the like so as not to inhibit the radical polymerizability.

Further, low molecular weight polypropylene (number average molecular weight = 1500 to 9000), low molecular weight polyethylene or the like may be added as a fixing property improving agent. Further, an azo-based metal complex, a quaternary ammonium salt, or the like may be used as a charge control agent.

In addition, from the viewpoint of imparting fluidity, inorganic fine particles and organic fine particles may be added to colored particles obtained by polymerization. In this case, use of inorganic fine particles is preferable, and use of inorganic oxide particles such as silica, titania, and alumina is preferable.These inorganic fine particles are subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, or the like. Is preferred.

The toner of the present invention can be produced by associating a plurality of the above-described polymers themselves. In this case, the dispersion liquid of the polymer particles is stirred with a metal as an aggregating agent. The salt can be obtained by adding the salt in an amount not less than the critical coagulation concentration, further adding a solvent (for example, isopropyl alcohol) that is infinitely soluble in water, and further performing heat treatment at a temperature equal to or higher than the glass transition temperature of the polymer.

The particle diameter of the toner of the present invention is 3 by volume average particle diameter.
９9 μm. Preferably it is 4 to 8 μm.
This particle size can be controlled by the concentration of the flocculant, the amount of the organic solvent added, and the composition of the polymer itself. Note that the volume average particle size of the colored particles is determined by Coulter Counter T
It is measured by A-II or Coulter Multisizer.

Structure of Carrier The carrier used in the present invention is formed by coating the surface of the core particles with a polymer of cyclic acrylate and / or cyclic methacrylate.

Specific examples of the monomer for forming the cyclic acrylate and / or cyclic methacrylate polymer include cyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl methacrylate, cyclopentyl methacrylate and the like. can give. Further, these monomers may be used alone or may be copolymers with various vinyl monomers shown below. Examples of other vinyl monomers include styrene,
o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene,
3,4-dichlorostyrene, p-phenylstyrene, p
-Ethylstyrene, 2,4-dimethylstyrene, pt
-Butylstyrene, pn-hexylstyrene, pn
-Octyl styrene, pn-nonyl styrene, pn
Styrene or a styrene derivative such as -decylstyrene or pn-dodecylstyrene, and methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, or n-methacrylate. Octyl, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and other methacrylate derivatives, methyl acrylate, ethyl acrylate, isopropyl acrylate, N-butyl acrylate, t-butyl acrylate,
Examples thereof include acrylate derivatives such as isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, and diethylaminoethyl acrylate. Particularly preferred copolymerization components are methacrylic acid esters or acrylic acid esters, and those having a cyclic skeleton ester group having no cyclic or aromatic ring as the ester component. Although the reason for this is not clear, it is because the refresh effect, which is the effect of the present invention, can be more easily exhibited as compared with other copolymer components. The content of the cyclic acrylate and / or methacrylate in the copolymer is from 20% to 99%, preferably from 30 to 99%, more preferably from 50 to 99% by weight.

As the core particles of the carrier used in the present invention, magnetite and various ferrites are used, and preferably, magnetite or light metal ferrite containing an alkali metal and / or an alkaline earth metal is used.

The composition of the carrier is Li, Na
And / or alkaline earth metals such as Mg, Ca, Sr and Ba, and have the following composition.

(M ₂ O) _x (Fe ₂ O ₃ ) _{1 -x} or (MO) _x (Fe ₂ O ₃ ) _{1 -x} Further, a part of the M ₂ O and / or Fe ₂ O ₃ It may be replaced with an earth metal oxide. M is an alkali metal such as Li and Na described above and / or M
The alkaline earth metals of g, Ca, Sr, and Ba are shown. Further, x is 30 mole% or less, preferably 18 m
ole% or less, and further substituted alkaline earth metal and / or alkali metal oxide is 1 to 10 mole%.
Is preferred. More preferably, it is 3 to 15 mole%.

The reason why the light metal ferrite or magnetite is preferable is not only the pollution problem at the time of waste disposal, which has been frequently discussed in recent years, but also the weight of the carrier itself and the stress on the toner can be reduced. This is because it has the advantage that it can be performed.

The particle diameter of the carrier is 10 to 100 μm, preferably 20 to 80 μm in terms of volume average particle diameter. Further, the magnetization characteristics of the carrier itself include:
The saturation magnetization is preferably 20 to 80 emu / g.

As a method of coating the core with a resin, for example, a method of dissolving the resin in a solvent and coating the solution on the core by a spray drying method, or a method of statically coating the core with particles of the coating resin. A method of coating by applying mechanical energy after electrically attaching, a method of applying and melting the resin by heating to a melting temperature of the resin after the particles of the coating resin are electrostatically attached to the core, and dissolving the resin. Various methods can be used, such as a method of immersing the core in a solution and coating the same, and a method of coating a resin containing a curing agent, followed by heating to cure and coat the resin.

The amount of the resin coating may be an amount sufficient to uniformly coat the core surface. The amount of the resin is 0.1 to 5.0% by weight, preferably 0.5 to 3.0% by weight based on the core. When the amount of the resin is small, the effect cannot be exerted. When the amount of the resin is too large, the resin itself is released, which may cause an image defect.

Configuration of Image Forming Method The developing system in which the developer of the present invention can be used is not particularly limited. It can be suitably used for a contact developing method or a non-contact developing method. In particular, the developer of the present invention has a high charge rising property and is useful for a non-contact developing method.

That is, in the non-contact developing method, since the developing electric field has a large change, a minute change in the charging is large and acts on the development itself. For this reason, there is a large fluctuation with respect to a change in the charge amount of the toner. However, since the toner of the present invention has a high charge rising property, the change in charge is small and a stable charge amount can be secured, so that a stable image can be formed over a long period even by the non-contact developing method. it can.

For the contact type development, the layer thickness of the developer having the toner of the present invention is 0.1 to 8 m in the development area.
m, particularly preferably 0.4 to 5 mm. Also,
The gap between the photoconductor and the developer carrier is preferably 0.15 to 7 mm, particularly preferably 0.2 to 4 mm.

In the non-contact type developing system, the developer layer formed on the developer carrier does not come into contact with the photosensitive member. It is preferable to be formed by. In this method, a developer layer having a thickness of 20 to 500 μm is formed in a development region on the surface of the developer carrier, and a gap between the photoconductor and the developer carrier has a larger gap than the developer layer. The thin layer is formed by a magnetic blade using a magnetic force or a method of pressing a developer layer regulating rod against the surface of the developer carrier. further,
There is also a method in which a urethane blade, a phosphor bronze plate or the like is brought into contact with the surface of the developer carrier to regulate the developer layer. The pressing force of the pressing regulating member is preferably from 1 to 15 gf / mm. When the pressing force is small, the conveyance is likely to be unstable because the regulating force is insufficient. On the other hand, when the pressing force is large, the stress on the developer is increased, and the durability of the developer is likely to be reduced. A preferred range is 3 to 10 gf / mm. The gap between the developer carrier and the surface of the photoconductor needs to be larger than the developer layer. Further, when a developing bias is applied at the time of development, either a method of applying only a DC component or a method of applying an AC bias may be used.

The size of the developer carrying member is 10 mm in diameter.
Those having a size of ４０40 mm are preferred. When the diameter is small, the mixing of the developer is insufficient, and it is difficult to ensure sufficient mixing to give sufficient charge to the toner. When the diameter is large, the centrifugal force on the developer becomes large. ,
The problem of toner scattering is likely to occur.

After transferring the toner image to the transfer material, the toner remaining on the photosensitive member is removed by cleaning, and the photosensitive member is repeatedly used in the next process.

The mechanism for cleaning in the present invention is not particularly limited, and any known cleaning mechanism such as a blade cleaning system, a magnetic brush cleaning system, or a fur brush cleaning system can be used. A preferred cleaning mechanism is a blade cleaning method using a so-called cleaning blade.

[0061]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto. In this example, “parts” means “parts by weight”.

Colored Particle Production Example 1 A carbon black (Mogal L: manufactured by Cabot Corporation) treated with an aluminum coupling agent (Prenact Al-M: manufactured by Ajinomoto Co.) was used to obtain 10.67 g, and then 4.92 g of sodium dodecyl sulfate (120 ml) An aqueous dispersion of carbon black was prepared by adding the solution to a solution dissolved in pure water and applying ultrasonic waves with stirring. Further, a solid concentration of a low molecular weight polypropylene (number average molecular weight = 3200) emulsified in water with a surfactant while applying heat =
A 20% by weight emulsified dispersion was prepared. A low molecular weight polypropylene emulsified dispersion 43 was added to the carbon black dispersion.
g of styrene monomer and 98.1 g of n-
Butyl acrylate monomer 18.4 g, methacrylic acid monomer 6.1 g, t-dodecyl mercaptan 3.3
g, 850 ml of degassed pure water was added, and the temperature was raised to 70 ° C. while stirring under a nitrogen stream.

Then, 200 ml of pure water in which 4.1 g of potassium persulfate was dissolved was added and reacted at 70 ° C. for 6 hours. The resultant carbon black-containing colored particle dispersion is referred to as “dispersion 1”.

The primary particle size (light scattering electric permanent particle size analyzer ELS-800: manufactured by Otsuka Electronics Co., Ltd.) and molecular weight distribution (using GPC; molecular weight in terms of styrene) were measured. The results are shown in Table 1 below.

For 600 ml of this “dispersion liquid 1”, 2.
160 ml of a 7 mol% aqueous solution of potassium chloride was added, and 94 ml of isopropyl alcohol and 5.4 g of polyoxyethylene octyl phenyl ether (ethylene oxide having an average degree of polymerization of 10) were dissolved in pure water 40.
ml was added. Thereafter, the temperature was raised to 85 ° C., and the reaction was performed for 6 hours. Then, after the completion of the reaction, the reaction solution was filtered, washed with water, and dried to obtain the colored particles of the present invention. This is referred to as “colored particles 1”.

Production Example 2 of Colored Particles In the production example 1 of colored particles, C.I. I. Pigment Blue
The colored particles of the present invention were obtained in the same manner except that 15: 3 was used. The dispersion obtained here is referred to as “dispersion 2”,
The colored particles are referred to as “colored particles 2”.

Production Example 3 of Colored Particles In Production Example 1 of colored particles, C.I. I. Pigment Red 1
Colored particles of the present invention were obtained in the same manner except that No. 22 was used.
The dispersion obtained here is referred to as “dispersion 3”, and the colored particles are referred to as “colored particles 3”.

Production Example 4 of Colored Particles In Production Example 1 of colored particles, C.I. I. Pigment Yellow
Except using w17, the colored particles of the present invention were obtained in the same manner. The dispersion obtained here is referred to as “dispersion 4”,
The colored particles are referred to as “colored particles 4”.

Colored Particle Production Example 5 Colored particles of the present invention were obtained in the same manner as in Colored Particle Production Example 1, except that “dispersion liquid 1” was used and the amount of isopropyl alcohol to be added was 125 ml. This is referred to as “colored particles 5”.

Production Example 6 of Colored Particles In Production Example 1 of colored particles, using “dispersion liquid 1”, the amount of a 2.7 mol% aqueous potassium chloride solution to be added was 250 m
The colored particles of the present invention were obtained in the same manner except that 1 was used. This is referred to as “colored particles 6”.

Colored Particle Production Example 7 The same procedure as in Colored Particle Production Example 1 was carried out except that “dispersion liquid 1” was used, the amount of isopropyl alcohol to be added was 72 ml, and the amount of 2.7 mol% aqueous potassium chloride solution was 200 ml. Thus, the colored particles of the present invention were obtained. This is referred to as “colored particles 7”.

Colored Particle Production Example 8 The same procedure as in Colored Particle Production Example 1 was carried out except that “dispersion liquid 1” was used, the amount of isopropyl alcohol to be added was 72 ml, and the amount of a 2.7 mol% potassium chloride aqueous solution was 200 ml. Thus, the colored particles of the present invention were obtained. This is referred to as “colored particles 8”.

Comparative Colored Particle Production Example 1 Styrene-n-butyl acrylate copolymer (copolymer ratio = 85: 15, weight average molecular weight = 63000) 100
Parts, 10 parts of carbon black and 5 parts of low molecular weight polypropylene (number average molecular weight = 3200) were added and kneaded.
After pulverization and classification, comparative colored particles were obtained. This is designated as “colored particles for comparison 1”.

Various physical properties of the above “dispersion 1” to “dispersion 4”, “colored particles 1” to “colored particles 8” and “comparative colored particles 1” are shown in Tables 1 and 2 below.

[0075]

[Table 1]

[0076]

[Table 2]

Toner Production Examples The above-mentioned “colored particles 1” to “colored particles 8” and “colored particles for comparison 1” were treated with hydrophobic silica (average primary particle size = 1).
2 nm) was added at 1% by weight to obtain a toner. These are referred to as “Toner 1” to “Toner 8” and “Comparative Toner 1”.

Carrier Production Examples The following cores were used as carrier core particles.

[0079]

[Table 3]

The above core was coated with a resin by the following method to prepare a carrier.

Example of Carrier Production The carrier of the present invention was prepared with the composition shown in Table 4 below.

[0082]

[Table 4]

As a method of coating the resin with respect to the carrier in the above table, the resin in the table has a number average diameter of about 1 μm.
A dry coating method was used in which fine particles as primary particles of about 00 nm were dry-mixed with a nucleus, electrostatically attached, and then coated by applying a mechanical impact force.

The carrier and the toner were mixed to prepare a developer having a toner concentration of 6%. The developer prepared below is shown. Note that the carrier coated with a resin outside the present invention is referred to as “comparative carrier 1”.

[0085]

[Table 5]

The evaluation was performed using Konica 70 manufactured by Konica Corporation.
50 and high temperature and high humidity (33 ° C. /
An evaluation of 300 kc (kc represents 1,000 copies) was performed in an 80% RH environment. Initial and 300k
The image density after f and fog density were compared. The results are shown below. Here, the image density is an absolute reflection density using a Macbeth densitometer, and the fog density is a relative reflection density when the density of the image support is “0”.

[0087]

[Table 6]

As is evident from the results shown in Table 6, the developers 1 to 8 of the present invention have no problem in any property, whereas the developers 1 and 2 for comparison have poor properties at 300 kc.
It turns out that there is a problem in durability.

[0089]

Industrial Applicability According to the present invention, a two-component electrostatic image developer which can reduce stress on a toner, does not generate spent on a carrier, has a good charging rise, and has high durability, and development using the same. A method can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Asao Matsushima 2970 Ishikawacho, Hachioji City, Tokyo Konica Corporation

Claims (4)

[Claims] 1. An electrostatic image developer comprising at least a toner and a carrier, wherein the toner has a volume average particle diameter of 3
９9 μm and a BET specific surface area of 5 m ² / g or more, and the carrier is a carrier in which the surface of a core particle is coated with a cyclic acrylate polymer and / or a cyclic methacrylate polymer. Electrostatic image developer. 2. The electrostatic image developer according to claim 1, wherein the core is a ferrite containing an alkali metal and / or an alkaline earth metal. 3. The electrostatic image developer according to claim 1, wherein said nucleus is magnetite. 4. A developing method for developing an electrostatic latent image formed on an electrophotographic photoreceptor with a two-component electrostatic image developer comprising at least a toner and a carrier, wherein the toner has a volume average particle diameter of at least A carrier having a BET specific surface area of 3 to 9 μm and a BET specific surface area of 5 m ² / g or more, wherein the carrier is formed by coating the surface of core particles of the carrier with a cyclic acrylate polymer and / or a cyclic methacrylate polymer. A developing method using a component-based electrostatic image developer.