JP3079388B2 - Color developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used for developing an electric latent image or a magnetic latent image in an electrophotographic method or an electrostatic printing method, and more particularly, to a method for improving the image quality of a multicolor image. The present invention relates to a multicolor electrophotographic color developer using a markedly improved color developer.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, a method of developing an electrostatic latent image using toner is roughly classified into a method using a so-called two-component developer in which a small amount of toner is dispersed in a medium called a carrier, There is a method using a so-called one-component developer in which toner is used alone without using a carrier.

[0003] The present invention relates to a two-component developer comprising a toner and a carrier among the above-mentioned developers. The carrier constituting the two-component developer is roughly classified into a conductive carrier and an insulating carrier, and as the conductive carrier, usually oxidized or unoxidized iron powder is used, and the iron powder carrier is used as a component. The developer has a drawback that the triboelectric charging property with respect to the toner is unstable and that a visible image formed by the developer is fogged.

That is, toner adheres and accumulates on the surface of iron powder carrier particles with the use of a developer (spent toner).
As a result, the electric resistance of the carrier particles increases, the bias current decreases, and the triboelectrification becomes unstable. As a result, the image density of a visible image formed decreases, and fog increases. Therefore, if the copying operation is continuously performed by an electronic copying apparatus using a developer containing an iron powder carrier, the developer deteriorates in a small number of times, so that it is necessary to replace the developer at an early stage, resulting in a high cost. It will be.

[0005] A typical example of an insulating carrier is a carrier obtained by uniformly covering the surface of a carrier core material made of a ferromagnetic material such as iron, nickel, or ferrite with an insulating resin. In the developer using this carrier, toner particles are less likely to fuse to the carrier surface than in the case of the conductive carrier, and at the same time, it is easy to control the triboelectric charging property between the toner and the carrier, and the durability is high. This is advantageous in that it is particularly suitable for high-speed electronic copiers in that it has excellent service life and a long service life.

However, in this insulating carrier, the coating layer covering the surface of the carrier core material is uniform and friction with a specific color toner used with the carrier causes stable charging of a desired size and polarity. It is required to be obtained. That is, if the surface of the resin-coated carrier is non-uniform, frictional charging between the color toner and the carrier becomes unstable, and as a result, the image quality of a visible image obtained after copying is reduced.

Therefore, for the purpose of making the carrier surface after resin coating uniform, attempts have been made to smooth the surface layer of the carrier core itself and then coat the resin with the resin. However, according to this method, although the carrier surface is made uniform, the adhesion between the carrier core material and the coating resin becomes unstable, and the usable coating resin is limited to only a resin having good adhesion. If the amount of the coating resin is increased to further increase the coating strength, the carrier itself is strongly charged to the opposite polarity to the toner particles due to the insulating property of the coating resin, and the problem of carrier adhesion to the background portion is reduced. Will happen.

This tendency is remarkable in a non-magnetic color toner having no leak site in the toner itself. In particular, when a toner containing colorant-containing resin particles using a polyester binder having a high chargeability is used as a toner, the length is further increased. This is a problem especially at low humidity.

As a countermeasure, improvement directions have been studied from both the carrier side and the toner side (particularly, external additives of the toner).

On the carrier side, it has been proposed to disperse, for example, conductive carbon black or the like in a coating resin and coat the carrier with a purpose of eliminating carrier adhesion caused by the carrier itself being strongly charged. However, a stable coating state has not always been achieved so far, and new problems such as fog due to liberation of carbon black and the like due to long-term use have occurred.

As described above, the surface of the carrier core material and the characteristics of the resin-coated carrier have a close relationship, but the surface layer of the carrier core material and the like are described in, for example, JP-A-61-1515.
No. 51, the use of spherical magnetite as a carrier, the surface layer is limited in porosity, but the proposal only discloses the existence ratio of vacancies, the diameter of each vacancy It is not mentioned and is unsuitable for defining the surface state of the carrier core material.

Further, in Japanese Patent Application Laid-Open No. 2-108065, the average pore diameter on the surface of the carrier core material is limited, and the stability as a carrier and the life of the developer are remarkably improved.

However, when the average pore diameter is limited as described above, it is not possible to judge the penetration of the resin into the pores when the resin is coated on the carrier core material, and the optimum conditions of the resin coat are determined by trial and error. It was only.

As described above, there is a correlation between the surface state of the carrier core material and the electrophotographic properties, particularly the life of the developer. However, the production stability of the carrier and the quality of the developer, especially the quality of the multicolor image, are not necessarily limited. The conditions for achieving both stability were found to be extremely severe.

On the other hand, for the toner side, Japanese Patent Publication No. 52-32256 and Japanese Patent Application Laid-Open No. Sho 56-6 disclose a technique for adding a charge auxiliary agent such as chargeable fine particles to a toner.
No. 4352 discloses a resin fine powder having the opposite polarity to the toner,
Japanese Patent Application Laid-Open No. 61-160760 proposes a technique in which a fluorine-containing compound is added to a developer to obtain a stable triboelectric charging property, and many charging aids are being developed today. .

Further, various techniques have been devised as a method for adding the charging auxiliary as described above. For example, a method of attaching the toner particles to the surface of the toner particles by electrostatic force or van der Waals force between the toner particles and the charge auxiliary agent is generally used, and a stirrer, a mixer or the like is used. However, in this method, it is not easy to uniformly disperse the additive on the surface of the toner particles, and the presence of the additive which is not adhered to the toner particles and aggregates together to form a so-called free state is present. It is difficult to avoid. This tendency becomes more conspicuous as the specific electrical resistance of the charging aid increases and as the particle size decreases. In such a case, the performance as a developer is affected. For example, the amount of triboelectricity of the toner becomes unstable, so that the image density is not constant and the image has a lot of fog. Or, if continuous copying or the like is performed, the content of the charging auxiliary changes, and the image quality at the initial stage cannot be maintained.

As another addition method, there is a method in which a charging auxiliary is added in advance together with a binder resin and a colorant during the production of the toner. However, it is not easy to make the charge control agent uniform, and it is substantially in the vicinity of the toner particle surface that contributes to the chargeability, and the charge auxiliary agent and the charge control agent present inside the toner particles are charged. Therefore, it is not easy to control the amount of the charge auxiliary agent added and the amount of dispersion on the surface. Also, in the toner obtained by such a method, the amount of triboelectric charge of the toner is unstable, and it is not easy to obtain a toner satisfying the developer characteristics as described above. The fact is that satisfactory quality has not been obtained.

Further, in recent years, the demand for high definition and high image quality of a copying machine has been increasing in the market, and in this technical field, attempts have been made to achieve high image quality and color by reducing the particle size of toner. However, as the particle size becomes smaller, the surface area per unit weight tends to increase, and the amount of charge of the toner tends to increase. In addition, since the charged amount of the toner is large, the adhesion between the toners is strong, the fluidity is reduced, and problems occur in the stability of toner supply and in the application of tribo to the supplied toner.

In the case of a color toner, since it does not contain a magnetic substance or a conductive substance such as carbon black, there is no portion that leaks the charge, and the charge amount generally tends to be large. This tendency is more remarkable especially when a polyester binder having high charging performance is used.

In particular, in the case of a color toner, the following characteristics are strongly desired. (1) In order that the fixed toner does not diffusely reflect light and hinder color reproduction, the toner needs to be in a state of almost complete melting such that the shape of the toner particles cannot be determined. (2) It must be a colored toner having transparency that does not interfere with the toner layers of different colors under the toner layer. (3) Each of the constituent toners must have balanced hue and spectral reflection characteristics and sufficient saturation.

From such a viewpoint, many binder resins have been studied, but a toner satisfying all of the above characteristics has not yet been developed. Today, polyester resins are widely used as binder resins for color in the technical field. However, toners made of polyester resins are generally easily affected by temperature and humidity, and have an excessive charge amount under low humidity and high humidity. Under such circumstances, there arises a problem such as insufficient charge amount, and there is an urgent need to develop a color toner having a stable charge amount even in a wide range of environments.

[0022]

SUMMARY OF THE INVENTION An object of the present invention is to provide a color developer which has solved the above-mentioned problems.

That is, an object of the present invention is to provide a color developer which is hardly influenced by the environment such as temperature and humidity and has always stable triboelectricity.

Another object of the present invention is to provide a color developer which has clear image characteristics without fog and has excellent durability stability.

Another object of the present invention is to provide a carrier and a color developer which are excellent in the stability of the resin coat and the quality.

[0026]

According to the present invention, there is provided a color developer comprising at least a non-magnetic colorant-containing resin particle, a color toner containing an external additive, and a carrier.
The toner has an external additive having a particle size of 0.02 to 0.2 μm.
m, and contains titanium oxide fine particles having a hydrophobicity of 20 to 80%.
A carrier having a weight average particle size of 10 to 200 μm coated with a resin of 0.05 to 5.0% by weight based on the weight of the carrier core material, and having a number average molecular weight (Mn) of 1
And the glass transition temperature (T
g) is 55 to 140 ° C., and when the specific surface area of the carrier by the permeation method is A (cm ² / g) and the specific surface area by the BET method is B (cm ² / g), the specific surface area ratio B
/ A is 1.1 ≦ B / A ≦ 1.7.

Hereinafter, each component of the developer of the present invention will be described in detail.

The reason why the Tg of the carrier coat resin is in the above range is as follows. That is, a carrier coat resin having a Tg lower than 55 ° C. is excellent in adhesion to the core material, but easily causes toner adhesion (spent) to the carrier, and particularly, the degree of curing of the resin under high temperature conditions is low. It is insufficient, and the fluidity of the carrier alone is deteriorated, and the charging ability is lowered, which is a problem. on the other hand,
At a Tg higher than 55 ° C., as the Tg increases, the toner adhesion resistance increases, but the adhesion to the core material decreases. Particularly, in the case of a resin exceeding 140 ° C., the adhesion becomes extremely weak, and even if the resin is heated to Tg or more, the resin is peeled off from the core material or cracks are generated.

Therefore, the Tg of the coated resin of the present invention is 55
C. to 140.degree. C. is good, preferably 60.degree.

In order to carry out coating most stably in the present invention, the remaining monomer in the coat resin is reduced to 50 to 50%.
It is necessary to contain 3,000 ppm. Especially Tg
It has been found that the higher the content, the better the results. This is because the configuration is such that the decrease in adhesion due to an increase in Tg is compensated for by the presence of a residual monomer. However, Tg is 14
It has been found that it is difficult to suppress deterioration during printing for a resin exceeding 0 ° C. even if a residual monomer is present in the resin.

The reason why the carrier coated with a resin containing a certain amount of the residual monomer in the resin is extremely effective in stabilizing the charge is not clear, but it is probably not clear that the residual monomer is present between the polymer and the core material during coating. The presence of a small amount increases the wettability of the polymer to the core material surface, and makes it possible to attach the polymer more uniformly than when no monomer is present.

However, if the amount of the residual monomer is too large, adverse effects such as a decrease in the adhesion strength to the core material occur.
In the present invention, the content of the residual monomer in the coat resin needs to be controlled to 50 to 3000 ppm based on the total amount of the coat resin. Preferably 50 to 1500 ppm
And more preferably 50 to 1000 ppm.

When the content of the remaining monomer is less than 50 ppm, coating unevenness is likely to occur on the carrier core material, and the adhesion of the resin to the core material is weakened. As a result, so-called ground fogging, which is the adhesion of toner to a non-image portion due to a decrease in tribo, occurs.

When the content of the remaining monomer is 300
If the amount exceeds 0 ppm, the charge amount is significantly reduced during long-term use of the developer, and toner scattering and a decrease in density occur. Such a tendency becomes more remarkable when a document having a large toner supply amount and a high image area ratio is used. The amount of the monomer remaining in the resin in the present invention can be determined using gas chromatography or the like.

The coating resin in the present invention preferably has a number average molecular weight (Mn) of 10,000 to 200,000, and more preferably 20,000 to 150,000. If the number average molecular weight exceeds 200,000, the adhesion to the core material is poor and the charge rises slowly, resulting in a decrease in the charge amount during running, resulting in early fog and contamination in the machine. It is not desirable because it occurs. On the other hand, if the number average molecular weight is less than 10,000, peeling due to internal destruction of the coating layer is remarkable, which causes a short life of the carrier and the developer, which is not preferable.

Furthermore, the molecular weight distribution of the coating resin is also important. In the present invention, the weight average molecular weight is at least 2 times the number average molecular weight in order to stably adhere the resin to the core material.
It is desired to have a value of not less than double and not more than 8 times.

Although the reason is not yet clear, if the weight average molecular weight is less than twice the number average molecular weight, the molecular weight distribution is sharp, but the adhesion to the core material during coating tends to be weak. Can be seen. When the weight average molecular weight exceeds eight times the number average molecular weight, the adhesion to the core material is sufficient, but the carrier is liable to be contaminated with the toner and adheres to the carrier surface after printing. Toner tends to be low.

As the polymer component used as the coating resin, the following can be used.

That is, alkyl styrene such as styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene, fluorostyrene, chloro Halogenated styrenes such as styrene, bromostyrene, dibromostyrene, iodostyrene, and styrene-based monomers such as nitrostyrene, acetylstyrene, and methoxystyrene; acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, α-methylcroton Acid, α-ethylcrotonic acid, isocrotonic acid, tiglic acid, addition-polymerizable unsaturated aliphatic monocarboxylic acid such as ungeric acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, Saconic acid, glutaconic acid, addition-polymerizable unsaturated aliphatic dicarboxylic acids such as dihydromuconic acid; the above-mentioned addition-polymerizable unsaturated carboxylic acids and alcohols, for example, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, Alkyl alcohols such as heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, and hexadecyl alcohol; halogenated alkyl alcohols obtained by partially halogenating these alkyl alcohols; methoxyethyl alcohol; ethoxyethyl alcohol; ethoxyethoxyethyl alcohol , Methoxypropyl alcohol, alkoxyalkyl alcohols such as ethoxypropyl alcohol, benzyl alcohol, Esters with aralkyl alcohols such as phenylethyl alcohol and phenylpropyl alcohol, alkenyl alcohols such as allyl alcohol and crotonyl alcohol, especially alkyl acrylate, alkyl methacrylate, alkyl fumarate, alkyl maleate and the like Are preferred examples; amides and nitriles derived from the addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene, and isobutylene; vinyl chloride, vinyl bromide,
Vinyl iodide, 1,2-dichloroethylene, 1,2-dibromoethylene, 1,2-diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride, fluoride Halogenated aliphatic olefins such as vinylidene; 1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene;
Conjugated diene-based aliphatic diolefins such as 2,4-hexadiene and 3-methyl-2,4-hexadiene; 2-vinylpyridine, 4-vinylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5- Methylpyridine, 4-
Butenylpyridine, 4-pentylpyridine, N-vinylpiperidine, 4-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N-vinylpyrrole, 2-vinylpyrrole, N-vinylpyrroline, N-vinylpyrrolidine, 2-vinyl Pyrrolidine, N-vinyl-
Examples thereof include nitrogen-containing vinyl monomers such as 2-pyrrolidone, N-vinyl-2-piperidone, and N-vinyl carbazole. These can be used alone or in combination of two or more.

Examples of the polymerization initiator used for producing the coating resin include azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, Known initiators such as peroxides such as benzoyl peroxide and lauroyl peroxide are used. Besides this, γ-
Combinations with ionizing radiation such as X-rays, accelerated electron beams and various sensitizers are also used.

The amount of the polymerization initiator such as an azo compound and a peroxide may be a so-called catalyst suitable amount, and is generally preferably used in an amount of 0.1 to 10% by weight per charged monomer. The polymerization reaction temperature may be a known one, and a temperature of 40 to 140 ° C. is generally sufficient. The stirring of the reaction system may be gentle stirring so that a homogeneous reaction occurs as a whole, and the polymerization is carried out by replacing the reaction system with an inert gas such as nitrogen to prevent the polymerization from being inhibited by oxygen. You may. Then, the obtained polymer is recovered, and if necessary, the polymer is immersed in a highly volatile solvent which is compatible with the monomer and does not dissolve the polymer component, and is stirred.

The preferred solvent is conveniently selected depending on the resin component of the resin particles to be produced and the polymerizable monomer used, but is preferably water, methanol, ethanol, propanol, butanol, isobutanol, tert-butanol, hexanol, or the like. Alcohols such as octanol, n
-Hexane, pentane, heptane, octane, isooctane, decane, 2,2'-dimethylbutane, aliphatic hydrocarbons such as cyclohexane, benzene, toluene, aromatic hydrocarbons such as xylene, dichloromethane, dichloroethane, carbon tetrachloride, Halogenated hydrocarbons such as chlorobenzene, dioxane, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,
Various solvents such as ethers such as ethylene glycol dimethyl ether and ethylene glycol diethyl ether, ketones such as acetone, methyl ethyl ketone and cyclohexanone, acetonitrile, formamide, dimethylformamide and diethylformamide are used. The above solvents may be used alone, but depending on the resin, two or more solvents can be used as a mixed solvent.

An operation for extracting the remaining monomer in a required amount of about 0.01 to 5 hours while leaving a required amount is performed.

The immersed and agitated polymer is filtered to obtain a carrier coating resin. The resin thus obtained contains an appropriate amount of the remaining monomer, and becomes a resin for carrier coating having excellent durability and charge stability.

The amount of the coating resin applied to the carrier core material according to the present invention is 0.05 to 30% by weight, preferably 0.2 to 10% by weight, based on the solid resin.
If the amount is less than 0.05% by weight, the effect of covering the carrier core material with the resin is not sufficient, and the amount of application exceeding 30% by weight is meaningless. Is not preferred.

In the carrier of the present invention, when the specific surface area by the permeation method is A (cm ² / g) and the specific surface area by the BET method is B (cm ² / g), the specific surface area ratio B / A
Is also one feature that 1.1 ≦ B / A ≦ 1.7.

That is, when the specific surface area ratio is within the above range, the carrier itself has appropriate irregularities, the toner carrying ability is improved, and the charging of the toner particles is maintained uniformly and stably. This tendency is more effective when an original having a large image area ratio such as a photo original is used.
Furthermore, the fact that the carrier itself has moderate irregularities is effective in uniformly charging the concave portions in a toner having irregularities such as a so-called pulverized toner having a kneading, pulverizing, and classifying process.

In the present invention, the specific surface area ratio B in the above-mentioned range.
/ A is required to achieve the specific surface area ratio D of the carrier core material.
/ C (C: specific surface area by transmission method, D: specific surface area by BET method) is preferably 1.2 to 2.5.

That is, when D / C is smaller than 1.2,
When the resin is coated, the surface becomes too smooth and only a very small amount of resin can be used to achieve the B / A of the present invention, resulting in unsatisfactory resin coating, Problems such as poor charging and carrier adhesion will occur. On the other hand, if the D / C is greater than 2.5, the penetration of the resin into the core material during the resin coating becomes unstable, and even if the resin coating is performed under the same conditions,
The performance is not constant, resulting in a decrease in productivity.

The specific surface area of the carrier core material in the present invention may be a value obtained by measuring the carrier after the coated carrier is heated at 600 ° C.

The weight average particle size of the carrier core material used is 17 to 200 μm, preferably 20 to 65 μm (measurement of the particle size distribution of the carrier is based on JIS-H2601). The average particle size is determined from the obtained measured particle size distribution according to the following equation.

[0052]

(Equation 1) As a material of the magnetic particles used in the present invention, 98% or more of Cu—Zn—Fe (metal composition ratio (5 to 20): (5
To 20): Ferrite particles having a composition of (30 to 80)) are preferable for easy surface uniformization and stable charging ability, but are not particularly limited, and may be flat, spongy, or the like.
Iron oxide powder of various shapes such as coin shape, spherical shape, true spherical shape, copper,
Use of ferrite containing one or more of manganese, cobalt, nickel, zinc, tin, magnesium, lead, strontium, barium, lithium, etc., and particles made of a mixture of various resins and magnetic powders Can be.

For resin coating on the core material, for example, one or two of the polymers prepared as described above
A method in which a core material is immersed in a solution obtained by dissolving a mixture of at least two or more species in an appropriate solvent, and then desolvation, drying, and high-temperature baking, or the core material is suspended in a fluidized bed, and the copolymer is obtained. A method of spray-coating a solution, drying and baking at a high temperature can be used. In these methods, the high-temperature baking treatment is preferably performed at about 80 to 240 ° C. from the viewpoint of removing residual monomers and increasing the adhesion strength between the core material and the copolymer layer.

In the present invention, the mixing ratio of the toner and the carrier is 1.0% by weight or less as the toner concentration in the developer.
Good results are usually obtained at 12% by weight, preferably 2% to 9% by weight. When the toner concentration is less than 1.0% by weight, the image density is low and cannot be used practically. When the toner concentration is more than 12% by weight, fog and scattering in the machine are increased, and the service life of the developer is shortened.

Further, in the present invention, as an external additive in the toner, the particle diameter is 0.02 to 0.2 μm, and the hydrophobicity is 20 to 20 μm.
One feature is that it contains 80% of titanium oxide fine particles.

That is, they have found that the above-mentioned titanium oxide fine particles are extremely effective in terms of stabilizing charging and imparting fluidity. This has not been achieved with the commonly known hydrophobic silica as a flow improver. The reason for this is that silica fine particles themselves are strongly negative, whereas titanium oxide fine particles are almost neutral.

In order to make the degree of hydrophobicity of titanium oxide 20 to 80%, it is particularly preferable to carry out a surface treatment with silicon oil or silicon varnish in an aqueous system. It has been conventionally proposed to add hydrophobic titanium oxide, but titanium oxide fine particles originally have a smaller surface activity than silica,
Hydrophobicization was not always performed sufficiently. In addition, when using a large amount of a treating agent or the like, or using a highly viscous treating agent or the like, although the degree of hydrophobicity is certainly increased, coalescence of particles occurs, and the ability to impart fluidity is reduced, Both the stabilization of charging and the provision of fluidity have not necessarily been achieved.

According to the present invention, however, the surface treatment is carried out with silicon oil or silicon varnish while mechanically dispersing the titanium oxide fine particles to have a primary particle size in an aqueous system. It is also found that the particles are hardly generated, and that the repulsion between the particles by the treatment acts, so that the titanium fine particles are surface-treated in a substantially primary particle state.

To make the present invention more effective,
Further, it is effective to perform a surface treatment with a coupling agent having a low viscosity in the gas phase so that the particles do not coalesce. The purpose of this was to seal the functional group of titanium oxide remaining in the treatment in an aqueous system with a coupling agent, but surprisingly, its reactivity was once treated in an aqueous system because it was once treated in an aqueous system. , Was found to be very high. Although the reason for this is not clear yet, since the organic treatment has been carried out in an aqueous system in advance, the site other than the reactive group of the coupling agent and the site of the lipophilic group of the titanium oxide fine particles are well compatible, and the reaction efficiency is high. It is presumed that it is raised. Therefore, in the present invention, a coupling agent can be selected in a very wide range from low viscosity to high viscosity, and it is very effective in terms of charging ability and fluidity-imparting ability.

In the present invention, the degree of hydrophobicity of the titanium oxide fine particles is 20 to 80%, preferably 30 to 70%.
If the degree of hydrophobicity is less than 20%, the charge amount is greatly reduced due to long-term storage under high humidity, and a mechanism for accelerating the charge on the hard side is required, and the apparatus becomes complicated. It is difficult to control the charging of the titanium oxide fine particles themselves, and as a result, the toner is charged up under low humidity.

The particle size is 0.02 to 0.2 μm, preferably 0.02 to 0.1 μm, from the viewpoint of imparting fluidity.
m is good. When the particle size is larger than 0.2 μm, toner charging due to poor fluidity becomes non-uniform, and as a result, toner scattering, fogging and the like occur. On the other hand, if the thickness is smaller than 0.02 μm, the toner is liable to be embedded on the surface of the toner, so that the toner deteriorates quickly and the durability is reduced. This tendency is more remarkable in the sharp-melt color toner used in the present invention.

[0062] The silicone oil used in the present invention is not particularly limited.

[0063]

Embedded image (R ₁ , R ₂ are CH ₃ or OH) dimethylpolysiloxane type represented by the general formula

[0064]

Embedded image Methyl hydrogen polysiloxane type represented by the general formula

[0065]

Embedded image And a methylphenylpolysiloxane type represented by Further, if necessary, alkyl modification,
Amino modification, epoxy modification, epoxy / polyether modification, carboxyl modification, mercapto modification, alcohol modification, fluorine modification and the like may be performed.

The silicone oil preferably has a viscosity at 25 ° C. of 50 to 1000 centistokes. If it is less than 50 centistokes, the volatile component is large, and the treatment effect is not long lasting. If it exceeds 1,000 centistokes, it is difficult to perform uniform treatment in an aqueous system, and the treatment efficiency is extremely deteriorated.

The silicon varnish used in the present invention is also 2
It does not matter if the viscosity at 5 ° C. is 50 to 1000 centistokes.

In the present invention, the treatment amount of silicon oil or silicone varnish is 1 to 40 parts by weight, preferably 2 to 30 parts by weight, based on 100 parts by weight of titanium, in terms of solid fraction.

The silane coupling agent used in the present invention has a general formula R _m SiY _n R: an alkoxy group or a chlorine atom m: an integer of 1 to 3 Y: a hydrocarbon containing a vinyl group, a glycidoxy group, and a methacryl group Group n: represented by an integer of 3 to 1, typically, for example, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltrichlorosilane. Examples include ethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinylchlorosilane, and the like.

The treatment of the fine powder with the silane coupling agent may be a dry treatment in which the vaporized silane coupling agent is reacted with the fine powder formed into a cloud by stirring or the like. The silane coupling agent is used in an amount of 1 to 20 parts by weight, preferably 3 to 1 part by weight, per 100 parts by weight of the fine powder.
It is good to treat it as 0 parts by weight.

In the present invention, the external additive has a polarity opposite to that of the colorant-containing resin particles and an average particle diameter of 0.5 to 0.02.
μ, preferably particle size 0.2-0.02μ and 0.3-
Addition of organic resin particles having two peaks at 0.8 μ has a further effect.

The reason is that the charge-up of the toner used in the present invention is neutralized by the aforementioned organic resin particles.

Further, by adding the organic resin particles, the rise of the charge of the toner is promoted, and a very stable charge characteristic is achieved from the beginning.

The reason for this is not clear yet, but is presumed as follows. That is, the organic resin particles are strongly attracted and charged toward the charging member rather than the colorant-containing resin particles at the beginning of the rubbing of the toner with the charging member such as a carrier. Therefore, the rising of the charge of the colorant-containing resin particles having the opposite polarity is promoted. On the other hand, once the toner particles have risen, the toner particles are more strongly attracted to the colorant-containing resin particles than the charge-imparting member, and function to neutralize excessive charge. The charge level can be maintained good and stable in various environments.

In order to make the above-mentioned action more effective, the particle size of the organic resin particles is 0.02 to 0.2 μm and 0.2 to 0.2 μm.
It is preferable to have two peaks at 3 to 0.8 μ. The existence ratio of the larger peak is 20% by weight.
Below, 2% by weight or more, preferably 13% by weight or less and 3% by weight or more are good. When the particle size is smaller than the above range, the organic resin particles are strongly adhered to the colorant-containing resin particles,
The effect described above disappears due to being embedded. On the other hand, if it is larger than the above range, the dispersion becomes non-uniform or liberates, and the effect is lost.

In the present invention, the content is preferably 0.1 to 5.0% by weight with respect to the colorant-containing resin particles in order to reliably exhibit the performance and to have a stable negative charging property.

Further, the organic resin particles of the present invention are also suitable when the diameter of the toner is reduced.

That is, when the diameter of the toner is reduced, the number of contact points between the toner and the carrier increases, so that carrier spent tends to occur, or the number of contact points between the toner and the toner increases, so that toner blocking easily occurs. On the other hand, spherical organic resin particles having an appropriate size of 0.2 to 0.02 μm as organic resin particles serve as good spacers and exert a good effect. For the toner blocking, it is more effective to use the opposite polarity resin particles having a higher Tg than the toner resin.

As described above, there are some examples in which resin particles of opposite polarity are added to the toner.
JP-A-4-45135 and JP-B-52-32256 propose the addition of colorless resin particles smaller than toner particles.

However, in these examples, the toner and the opposite polarity resin particles behave separately, and the toner adheres to the latent image portion during development, whereas the opposite polarity resin particles adhere to the background portion.

That is, the opposite polarity resin particles function to promote charging of the toner. However, in the present invention, the opposite polarity resin particles are used which are sufficiently small with respect to the toner particle diameter, and are finally strongly adhered to the toner, developed integrally, and 0.3 to 0.8 μm in the transfer residue. The present invention is different from the above-described invention because it is characterized in that the resin particles on the relatively coarse side are appropriately left to improve the cleaning property.

More recently, systems using silica and organic resin particles at the same time have been proposed as disclosed in Japanese Patent Application Laid-Open No. 1-113767, but these systems are used to weaken the adhesion between the drum and the toner. Is what it is. However, in the present invention, the structure having the function of weakening the adhesive force on the drum side is used for the purpose of further improving the cleaning characteristics, that is, for the purpose of appropriately removing foreign substances on the drum. Therefore, the present invention is different from the above invention.

Further, Japanese Patent Publication No. 2-3172 and the like propose a system to be used for the purpose of not lowering the charge of the toner. However, in the present invention, a non-magnetic color toner, which tends to be excessively charged, is used. On the other hand, it is a different invention in which the charge is lowered by positively using it.

The monomers constituting the opposite polarity resin particles used in the present invention are not particularly limited, but need to be selected in consideration of the charge amount of the toner and the like. Specific examples of the addition-polymerizable monomer that can be used in the present invention include the following monomers.

That is, styrene and its derivatives, for example, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, alkylstyrene such as octylstyrene, fluorostyrene , Chlorostyrene,
Examples include halogenated styrenes such as bromostyrene, dibromostyrene, and iodostyrene, and nitrostyrene, acetylstyrene, and methoxystyrene.

Further, addition-polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, α-methylcrotonic acid, α-ethylcrotonic acid, isocrotonic acid, tiglic acid, and ungeric acid And addition-polymerizable unsaturated aliphatic monocarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid and dihydromuconic acid.

Further, metal chlorination of these carboxylic acids can also be used, and this metal chlorination can be carried out after completion of the polymerization.

Further, the addition polymerizable unsaturated carboxylic acid and alkyl alcohol, halogenated alkyl alcohol,
Examples thereof include an esterified product with an alcohol such as an alkoxyalkyl alcohol, an aralkyl alcohol and an alkenyl alcohol. And, as specific examples of the alcohol, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol,
Alkyl alcohols such as hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, and hexadecyl alcohol; halogenated alkyl alcohols obtained by partially halogenating these alkyl alcohols; methoxyethyl alcohol, ethoxyethyl alcohol, ethoxy Alkoxyalkyl alcohols such as ethoxyethyl alcohol, methoxypropyl alcohol and ethoxypropyl alcohol; aralkyl alcohols such as benzyl alcohol, phenylethyl alcohol and phenylpropyl alcohol; and alkenyl alcohols such as allyl alcohol and crotonyl alcohol.

Amides and nitriles derived from the above-mentioned addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene and isobutylene; vinyl chloride, vinyl bromide, vinyl iodide, 1,2-
Dichloroethylene, 1,2-dibromoethylene, 1,2
-Diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride,
Halogenated aliphatic olefins such as vinyl fluoride and vinylidene fluoride; 1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene; , 4-hexadiene, 3-
Examples thereof include conjugated diene-based aliphatic diolefins such as methyl-2,4-hexadiene.

Further, there may be mentioned vinyl acetates, vinyl ethers and nitrogen-containing vinyl compounds such as vinyl carbazole, vinyl pyridine and vinyl pyrrolidone.

The fine powder according to the present invention contains these monomers 1
A species or a polymer obtained by polymerizing two or more species can be used.

The reverse polarity resin particles used in the present invention are not limited to using only one kind, but a plurality of kinds can be used in combination.

The method for producing the opposite polarity resin particles used in the present invention includes spray drying, suspension polymerization, and the like.
Any method that can produce spherical fine particles, such as an emulsion polymerization method, a soap-free polymerization method, a seed polymerization method, and a mechanical pulverization method, can be used. Among them, a soap-free polymerization method, which has no residual emulsifier and does not hinder the chargeability of the toner and has little environmental change in specific electric resistance, is particularly suitable, but is not particularly limited.

In order to make the resin particles used in the present invention have two peaks, the two types of particles may be dried after being dry-blended or wet-blended, but it is preferable that the primary particles be dried when the emulsion is dried from an emulsion state. To moderately combine
More preferably, two peaks are achieved. Further, if necessary, heat treatment or crushing treatment may be performed.

The opposite polarity resin particles may be subjected to a particle surface treatment as required. As a surface treatment method, a metal such as iron, nickel, cobalt, copper, zinc, gold, silver, or the like is subjected to a surface treatment by a vapor deposition method, plating, or the like, or a metal oxide such as the above metal, a magnetic material, or conductive zinc oxide. An organic compound capable of being triboelectrically charged, such as a method of fixing an object or the like by ion adsorption or external addition, a pigment or a dye, or a polymer resin, may be supported by coating or external addition.

The molecular weight distribution of the opposite polarity resin particles used in the present invention must have a peak molecular weight in the range of 10,000 to 5,000,000, and preferably in the range of 20,000 to 1,000,000. When the peak molecular weight is larger than 5,000,000, the fixability of the color toner is adversely affected. When the peak molecular weight is smaller than 10,000, the magnetic particles are contaminated or the blocking resistance is deteriorated.

The toner according to the present invention may contain a charge control agent in order to stabilize the charge characteristics. At that time, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable. Examples of the negative charge control agent in this case include an organic metal complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid). When the negative charge control agent is blended in the toner, 0.1 to 10 parts by weight based on 100 parts by weight of the binder resin.
It is advisable to add 0.5 parts by weight, preferably 0.5 to 8 parts by weight.

As the colorant used in the present invention, known dyes and pigments, for example, phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hanza yellow, permanent yellow, benzine yellow and the like are widely used. can do. The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin so as to reflect sensitively on the permeability of the OHP film.

If necessary, additives may be added to the toner of the present invention as long as the properties of the toner are not impaired. Examples of such additives include Teflon, zinc stearate and polyvinylidene fluoride. And a fixing aid such as low molecular weight polyethylene and low molecular weight polypropylene.

In the production of the toner of the present invention, the constituent materials are kneaded well by a hot kneader such as a hot roll, a kneader, an extruder and the like, and are then obtained by mechanical pulverization and classification, or in a binder resin solution. A method in which a material such as a colorant is dispersed and obtained by spray drying, or a method in which a predetermined material is mixed with a monomer to constitute a binder resin, and then the emulsified suspension is polymerized to form a toner. Each method such as a method for producing a polymerized toner to be obtained can be applied.

As the binder used in the colorant-containing resin particles of the present invention, various material resins conventionally known as electrophotographic toner binder resins are used.

For example, styrene-based copolymers such as polystyrene, styrene-butadiene copolymer and styrene-acrylic copolymer, and ethylene-based copolymers such as polyethylene, ethylene / vinyl acetate copolymer and ethylene / vinyl alcohol copolymer Copolymer, phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, polyester resin, maleic acid resin and the like. In addition, the production method of any resin is not particularly limited.

Among these resins, when a polyester resin having a particularly high negative chargeability is used, the effect of the present invention is remarkable. That is, the polyester-based resin has excellent fixability and is suitable for a color toner, but on the other hand, the negative charging ability is strong and the charging is liable to be excessively large. A toner is obtained.

In particular, the following equation

[0105]

Embedded image (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2
10 to 10. A) a carboxylic acid component consisting of a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid,
A polyester resin obtained by co-condensation polymerization of maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) is more preferable since it has sharp melting properties.

In the present invention, an electrically insulating resin is used as a coating resin on the carrier surface, and is appropriately selected depending on a toner material and a carrier core material. In the present invention, at least one monomer selected from at least an acrylic acid (or an ester thereof) monomer and a methacrylic acid (or an ester thereof) monomer in order to improve the adhesion to the carrier core material surface. It is desirable to contain In particular, when a polyester resin particle having a high negative chargeability is used as a toner material, it is preferable to further form a copolymer with a styrene-based monomer for the purpose of stabilizing charging, and the copolymerization weight ratio of the styrene-based monomer is used. Is preferably 5 to 70% by weight.

The monomer for the coating resin of the carrier core material that can be used in the present invention includes:
For example, styrene monomer, chlorostyrene monomer, α
-Methylstyrene monomer, styrene-chlorostyrene monomer and the like. Examples of the acrylic monomer include, for example, acrylate monomer (methyl acrylate monomer, ethyl acrylate monomer, butyl acrylate monomer, octyl acrylate monomer, phenyl acrylate monomer) And methacrylic acid ester monomers (methyl methacrylate monomer, ethyl methacrylate monomer, butyl methacrylate monomer, phenyl methacrylate monomer).

The measuring method according to the present invention will be described below. 1) Measurement method of triboelectric charge amount The measurement method will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of an apparatus for measuring a triboelectric charge amount of a toner. First, 50 g of a 1:19 weight ratio mixture of toner and carrier whose frictional charge is to be measured is placed in a 50-1000 ml polyethylene bottle in a metal measuring container 2 having a 500-mesh screen 1 at the bottom. , 30 times and 500 times by hand, about 0.5 to 0.9 g of the mixture (developer) is put in, and the metal lid 3 is closed. At this time, the weight of the entire measurement container 2 is weighed and W ₁
(G). Next, in the suction device 4 (at least the portion in contact with the measurement container 2 is an insulator), the pressure of the vacuum gauge 7 is adjusted to 250 mmA by adjusting the air volume control valve 6 by suctioning from the suction port 5.
q. In this state, suction is sufficiently performed, preferably for about 2 minutes, to remove the toner by suction. The potential of the electrometer 8 at this time is set to V (volt). Here, reference numeral 9 denotes a capacitor whose capacity is C (μF). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). The triboelectric charge (μc / g) of this toner is calculated as in the following equation.

Amount of triboelectric charge of toner (μc / g) = C × V / (W ₁ −W ₂ ) 2) Method for quantifying monomer remaining in resin Gas chromatography (Shimadzu GC-15A).
As a standard component, the monomer used to obtain the polymer (eg, methyl methacrylate) is used. The resin to be measured is taken in acetone containing DMF, left in an ultrasonic cleaner for 30 minutes, filtered, injected, and measured by an internal standard method using a column of DB-1 by J & W. 3) Measurement method of molecular weight distribution In the present invention, the molecular weight distribution of a chromatogram by GPC (gel permeation chromatography) using THF as a solvent is measured under the following conditions.

That is, the column was stabilized in a heat chamber at 40 ° C., and THF (tetrahydrofuran) as a solvent was flown into the column at this temperature at a flow rate of 1 ml per minute, and about 100 μl of a THF sample solution was injected. Measure. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several kinds of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, one having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko KK is used.
It is appropriate to use about 0 standard polystyrene samples. An RI (refractive index) detector is used as the detector.
As the column, a plurality of commercially available polystyrene gel columns are preferably combined, and for example, showex GPC KF-801, 802, 80 manufactured by Showa Denko KK
3,804,805,806,807,800P or TSKgelG1000H (H
_{XL), G2000H (H XL)} , G3000H (H XL),
_{G4000H (H XL), G5000H (} H XL), G60
00H (H _XL ), G7000H (H _XL ), TSKgua
rdcolumn can be mentioned.

A sample is prepared as follows.

The sample is put in THF, left for several hours, shaken sufficiently, mixed well with THF (until the sample is no longer united), and left still for 12 hours or more. At this time, TH
The time of leaving in F is set to 24 hours or more. Then, a sample processing filter (pore size 0.45 to
0.5 μm, for example, Myshoridisk H-25-
5 (available from Tosoh Corporation, Exiclodisk 25CR manufactured by Germanic Science Japan) can be used as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml. 4) Measurement method of specific surface area by transmission method The measuring device is a powder specific surface area measuring device (SS-
100 type) and the following procedure. (1) A screen is placed in a plastic sample tube, a piece of paper is laid thereon, and a sample is put on the plastic plate up to 1/3 of the sample tube. (2) Set the sample tube on the tap stand of the powder tester and tap for 1 minute. (3) Place the sample in the tapped sample tube at 2 /
Insert up to 3. (4) Perform the same operation as (2). (5) Insert a supplementary tube (plastic) onto the sample tube, and put the sample on the heap from above. (6) Perform the same operation as above. (7) Withdraw the supplementary tube from the tapped sample tube and cut off the excess sample with a spatula. (8) Fill the water up to the S scale of the measuring tube for the specific surface area. (9) Connect the sample tube to the measurement tube. (After filling the sample, apply grease to the contact surface.) (10) Open the cock at the lower outlet and set the water level of the
Activate the stopwatch when passing the scale.
(The lower effluent is received in a beaker.) (11) Measure the time when the water surface drops to 20 scales (unit: cc). (12) Remove the sample cylinder and measure the weight of the sample. (13) The specific surface area is derived by the following formula.

[0114]

(Equation 2) SW = specific surface area of powder (cm ² / g) e = porosity of sample packed layer ρ = density of powder (g / cm ³ ) η = viscosity coefficient of fluid (g / cm · sec) L = sample Layer thickness (cm) Q = Amount of fluid permeating sample layer (cc) t = Time required for Qcc fluid (air) to permeate the sample layer (sec) ΔP = Pressure difference between both ends of sample layer (g / cm ²⁾ A) Cross-sectional area of sample layer (cm ² ) W = weight of sample (g) 5) Method for measuring particle size of organic resin particles Apparatus Coulter Counter N4 type as a measuring apparatus and Tommy Seiko Co., Ltd. as an ultrasonic generator for dispersion Use UD-200. Method An appropriate amount of a sample was put into 30 to 50 ml of distilled water to which a trace amount of surfactant was added, and the output was 2 to 2 using the ultrasonic generator.
6. Disperse for about 2 to 5 minutes. The suspension in which the sample is dispersed is transferred to a cell, and after the air bubbles are released, the suspension is set in the above-mentioned coulter counter in which the measurement temperature is set to 50 ° C. in advance. The measurement is started after elapse of 10 to 20 minutes in order to keep the sample at a constant temperature, and the volume average particle size distribution is determined. 6) Hydrophobicity measurement The methanol titration test is an experimental test for confirming the hydrophobicity of a titanium fine powder having a hydrophobized surface.

The "methanol titration test" defined herein for evaluating the degree of hydrophobicity of the treated titanium fine powder is carried out as follows. 0.2 g of the test titanium fine powder is added to 50 ml of water in a 250 ml Erlenmeyer flask. Methanol is titrated from the burette until all the titanium is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed as the entire amount of titanium fines is suspended in the liquid, and the degree of hydrophobicity is expressed as the percentage of methanol in the liquid mixture of methanol and water at the end point.

[0116]

【Example】

(Synthesis Example 1 of Titanium Oxide Fine Particles) Hydrophilic titanium oxide fine particles (0.05 μm in particle diameter, BET 140 m ² / g) were stirred and mixed in an aqueous system, and as a treating agent, dimethyl poly having a viscosity of 500 centistokes at 25 ° C. was used. The siloxane emulsion is converted to solid oxide equivalent of 10
%, And mix and dry so that the particles do not coalesce.
Disintegrated, hydrophobicity 30%, particle size 0.05μ, BET12
0 m ² / g of titanium oxide fine particles I were obtained.

(Synthesis Example 2 of Titanium Oxide Fine Particles) Titanium oxide fine particles I were further treated in the gas phase with 10% by weight of γ = chloropropyltrimethoxysilane to give a hydrophobicity of 50%.
Titanium oxide fine particles II having a particle size of 0.05 μm and a BET of 110 m ² / g were obtained.

(Synthesis Example 3 of Titanium Oxide Fine Particles) Titanium oxide fine particles I were further treated with 30% by weight of 5,000 centistokes dimethylpolysiloxane in the gas phase to obtain a hydrophobicity of 90%, a particle size of 0.07 μm, and a BET of 90 m. ² / g of titanium oxide fine particles III were obtained.

(Synthesis Example A of Resin for Carrier Coating) Methyl methacrylate / butyl acrylate (75: 2
5) Using a monomer, solution polymerization (initiator azobisisobutyronitrile 0.5%) is performed in a toluene solution, and T
g65 ° C., a resin solution having a number average molecular weight (Mn) of 90,000, a weight average molecular weight (Mw) of 300,000, and Mw / Mn = 3.3 was obtained. The amount of monomer remaining in this resin is 1600
ppm.

This resin solution was further diluted with toluene to obtain a resin solution A having a solid content of 10%.

(Synthesis Example B of Resin for Carrier Coating) Using methyl methacrylate monomer, Tg of 105 ° C.
A resin solution B having Mn = 130,000, Mw = 300,000, Mw / Mn = 2.3, and a residual monomer amount of 900 ppm was obtained.

Example 1 A spherical ferrite having a Cu-Zn-Fe composition having an average particle diameter of 47 µm was obtained using a resin solution A and a Spira coater manufactured by Okada Seiko Co., Ltd. C = 340 cm ² / g D = 610 cm ² / g D
/C=1.8. The obtained coated carrier was dried at 60 ° C. for 1 hour to remove the solvent, and further heated at 140 ° C. for 1 hour to obtain a coated carrier. The resin coating amount of the obtained carrier was 0.57% by weight.

This resin-coated carrier has A = 310 cm ² / g B = 420 cm ² / g B
/A=1.35.

On the other hand, polyester resin phthalocyanine pigment obtained by condensing 100 parts of propoxylated bisphenol and fumaric acid 4 parts Chromium complex of di-tert-butylsalicylic acid 2 parts The above compound was sufficiently premixed with a Henschel mixer and biaxially mixed. The mixture was melt-kneaded with an extruder, cooled, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized by an air jet pulverizer. Further, the obtained finely pulverized product is classified to have a particle size distribution of 2 to 1 according to the present invention.
0 μ was selected to obtain colorant-containing resin particles.

0.5 parts of titanium oxide fine particles II were added to 100 parts of the colorant-containing resin particles,
A cyan toner was obtained by combining 0.3 parts of styrene / methyl methacrylate resin particles having two peaks in μ.

The above-mentioned carrier was mixed with 5 parts of the cyan toner so that the total amount became 100 parts to prepare a developer.

Using this developer, a commercial plain paper color copying machine (manufactured by Color Laser Copier 500 Canon) was used to set the development contrast to 300 V, and an image was formed at 23 ° C./65%. The image had a high density of 1.47 and was clear without any fog. Thereafter, 20,000 copies were further made, during which the density fluctuation was as small as 0.1, and the fog and sharpness were equivalent to those at the initial stage. Further, under low temperature and low humidity (20 ° C., 10% RH), when the developing contrast was set to 300 V and an image was formed, the image density was as high as 1.43. It also suggests that it worked.

Further, when the development contrast was set to 300 V under high temperature and high humidity (30 ° C./80%) and an image was formed, the image density was very stable at 1.50 and a good image was obtained. Was.

Further, at 23 ° C./60% RH, at 20 ° C./10
%, 30 ° C./80%, no abnormality was observed in the initial image after being left for one month in each environment.

Example 2 An image was formed in the same manner as in Example 1 except that the titanium oxide fine particles I were used.
Although the image density was increased by 0.05 at 0%, it was rather superior in reproducing the highlight, and good results were obtained.

Example 3 In Example 1, the firing temperature of the spherical ferrite core material was changed to +
Increase by 20 ° C. C = 310 cm ² / g D = 420 cm ² / g D
/C=1.35 carrier core material was obtained. Using this carrier core material, carrier coating was performed in the same manner as in Example 1. A = 310 cm ² / g B = 370 cm ² / g B
/A=1.19 was obtained.

Using this carrier, image formation was carried out in the same manner as in Example 1. As a result of a standing test at 30 ° C./80%, fog was slightly observed as compared with Example 1.
The uniformity of the image density, in particular, the uniformity of the halftone portion was rather superior, and good results were obtained.

Example 4 A = 310 cm ² / g B = 350 cm ² / g B In the same manner as in Example 1 except that the resin solution B was used.
/A=1.13 was obtained.

When image formation was performed using this carrier in the same manner as in Example 1, the reproduction of highlights was slightly inferior, but the fog at 20,000 sheets was slightly superior.
Good results were obtained.

Comparative Example 1 An image was formed in the same manner as in Example 1 except that titanium oxide fine particles having a hydrophobicity of 0 not treated with dimethylpolysiloxane were used. The test resulted in a 0.15 increase in image density. Some fog was also observed.

Comparative Example 2 An image was formed in the same manner as in Example 1 except that the titanium oxide fine particles III were used.
The initial value was 1.37 at 65%, but dropped to 1.25 for 1000 sheets.

Comparative Example 3 In Example 1, the firing temperature of the spherical ferrite core material was set to 40.
C = 320 cm ² / g D = 380 cm ² / g D
The carrier core material of /C=1.19 was obtained. Using this carrier core material, carrier coating was performed in the same manner as in Example 1. A = 315 cm ² / g B = 340 cm ² / g B
/A=1.08 was obtained.

When image formation was performed using this carrier in the same manner as in Example 1, slight toner scattering occurred at 30 ° C./80%.

Comparative Example 4 In Example 1, the sintering temperature of the spherical ferrite core material was set to 40.
C = 350 cm ² / g D = 980 cm ² / g D
/C=2.8 very spherical ferrite porous average particle size 53μm but using as a carrier core material in the same manner as in Example ^{1 A = 340cm 2 / g B} = 630cm 2 / g B
/A=1.85 was obtained.

When image formation was performed using this carrier in the same manner as in Example 1, adhesion of the carrier was poor.

[0141]

According to the present invention, the present invention has a stable triboelectrification which is hardly influenced by the environment, and has excellent durability stability.
Further, a color developer having excellent resin coat stability can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an apparatus for measuring a triboelectric charge amount of a toner.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ryoichi Fujita 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-3-1966052 (JP, A) JP-A-62 -129861 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/09 G03G 9/113

Claims (3)

(57) [Claims] 1. A color developer comprising at least a non-magnetic colorant-containing resin particle, a color toner containing an external additive, and a carrier, wherein the toner has an external additive having a particle size of 0.02 to 0. .2
μm, and a toner containing titanium oxide fine particles having a hydrophobicity of 20 to 80%, wherein the carrier has a particle size of 0.05 to
Weight average particle diameter 10-20 coated with 5.0% by weight of resin
0 μm carrier, the number average molecular weight (Mn) of the coating resin is in the range of 10,000 to 200,000, the glass transition temperature (Tg) of the resin is 55 to 140 ° C., and the permeation of the carrier A (cm ² / g), BE
A color developer characterized in that the specific surface area ratio B / A satisfies 1.1 ≦ B / A ≦ 1.7, where B (cm ² / g) is the specific surface area by the T method. 2. The color developer according to claim 1, wherein the titanium oxide fine particles are titanium oxide fine particles surface-treated with silicon oil or silicon varnish in an aqueous system. 3. The titanium oxide fine particles according to claim 1, wherein the titanium fine particles are surface-treated with silicon oil or silicon varnish in an aqueous system, and then surface-treated with a coupling agent in a gas phase. Color developer.