JP2001060014A - Electrostatic latent image developer and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic latent image developer excellent in electrostatic charge characteristics, having improved environmental dependency, fluidity and caking resistance and capable of stably ensuring high image quality, and a method for forming an image using the developer. SOLUTION: The electrostatic latent image developer comprises a toner and a carrier. The toner contains toner particles containing a bonding resin and a colorant and at least two additives including fine titanium compound particles (A) and fine silica particles (B) in a B to A ratio of 1-3. The dynamic electric resistance of the carrier in an electric field of 1×10+4 V/cm is 10-1×10+8 Ωcm in the state of a magnetic brush.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image developer comprising a toner and a carrier used for developing an electrostatic latent image in electrophotography and electrostatic recording, and the electrostatic latent image developer. The present invention relates to an image forming method for forming a full-color image using an image developer.

[0002]

2. Description of the Related Art In electrophotography, a photoconductor (latent image carrier) is used.
Is developed with a toner containing a colorant, and the obtained toner image is transferred onto a transfer material such as transfer paper and fixed with a hot roll or the like to obtain an image. On the other hand, the photoconductor
The cleaning is performed to remove the remaining toner in preparation for the next image formation. Dry developers used in such electrophotography and the like are mainly classified into a one-component developer using only a toner in which a colorant is dispersed in a binder resin, and a two-component developer in which a carrier is mixed with the toner. Can be different. When a copying operation is performed using these developers, in order to satisfy process compatibility, the developers need to have excellent fluidity, anti-caking properties, fixing properties, charging properties, cleaning properties, and the like. is there. In particular, inorganic fine powders are often added to toners in order to enhance fluidity and anti-caking properties.

[0003] However, the inorganic fine powder has a great effect on the charging of the toner. For example, when a commonly used silica-based fine powder is used, the silica-based fine powder originally has a high insulating property, and accordingly, has a high chargeability and a strong negative polarity. In particular, under low temperature and low humidity, the charge of the negatively chargeable toner is excessively increased. On the other hand, under high temperature and high humidity, by taking in moisture, conductivity is increased and chargeability is reduced. Therefore, there is a problem (environmental dependency) that a large difference is caused in the charging property between the two environments. As a result, this may cause poor density reproduction and background fog.

[0004] The dispersibility of the inorganic fine powder also greatly affects the toner characteristics. When the dispersion of the inorganic fine powder is not uniform, desired characteristics of fluidity and anti-caking properties cannot be obtained, or cleaning becomes insufficient, toner sticking on the photoreceptor occurs, and a black dot image is formed. It could cause defects.

Various proposals have been made to use inorganic fine powders which have been surface-treated for the purpose of improving these. For example, JP-A-46-5782 and JP-A-48-473.
No. 45 and JP-A-48-47346 describe that the surface of silica fine particles is subjected to a hydrophobic treatment for the purpose of eliminating the influence of moisture. However, by using only these inorganic fine powders, it is not possible to obtain a sufficient effect on the difference in chargeability with respect to the environment, the charge stability of the developer against long-term stress, the secondary obstacle to filming on the photoreceptor, and the like.

As a method of alleviating the negative chargeability of the toner particles, a method of externally adding silica fine particles surface-treated with an amino-modified silicone oil (JP-A-64-7)
No. 3354) and a method of externally adding silica fine particles surface-treated with aminosilane and / or amino-modified silicone oil (JP-A-1-237561). However, the treatment with these amino compounds can suppress the excessive increase in the charge of the negatively chargeable toner, but cannot sufficiently improve the environmental dependency of the silica fine particles themselves. That is, although it is possible to slightly suppress the excessive negative chargeability of the silica fine particles after long-time use under low temperature and low humidity, the same charge neutralization occurs even in long-time use under high temperature and high humidity, so that Environmental dependency is not improved. In particular, when a polyester resin or an epoxy resin is used as the binder resin of the toner, an extreme difference occurs in the charging performance under high temperature and high humidity and under low temperature and low humidity.

Thus, external additives of inorganic compounds other than silica fine particles have been studied, and for example, a method of externally adding an inorganic oxide such as titanium oxide fine particles to a toner has been proposed (Japanese Patent Laid-Open No. 58-216252). No., JP-A-60-1
23,862, JP-A-60-238847, etc.).

The titanium oxide fine particles have a low charge level,
It is easy to control the charge level and environment dependency by the treatment agent. However, titanium oxide is generally obtained by purifying TiO (OH) ₂ obtained by a sulfuric acid method (wet method) using ilmenite ore, and heating the titanium oxide. Since it is produced by firing, there are naturally agglomerated particles as a result of dehydration condensation in the product produced by the production method, and it is not easy to re-disperse such agglomerated particles using existing techniques. That is, when crystalline titanium oxide (rutile: specific gravity 4.2, anatase: specific gravity 3.9) is taken out as fine powder, secondary and tertiary aggregation is formed. When this is used as an external additive, toner Has a significantly lower fluidity improving effect than silica fine particles. In particular, in recent years, the demand for high image quality such as color is increasing in the market. To achieve high image quality by reducing the particle size of toner particles (hereinafter, referred to as toner base particles, excluding external additives in the toner, the same applies hereinafter). However, when the toner particles are made finer, the adhesion between the particles increases, and the fluidity of the toner further deteriorates. This phenomenon is remarkable when titanium oxide fine particles are used as an external additive.

Therefore, in order to achieve both improvement in fluidity and environmental dependency of charging, it has been attempted to add hydrophobic titanium oxide fine particles and hydrophobic silica fine particles in combination (Japanese Patent Laid-Open No. 60-136755). ). This method can temporarily suppress the respective disadvantages of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles, but is easily affected by either additive depending on the dispersion state. In particular, when considering the maintainability, it is difficult to control the dispersion state of both on the toner surface to be constant, and either the hydrophobic silica fine particles or the hydrophobic titanium oxide fine particles are subjected to stress such as aging or stirring. Features are easy to appear. That is, it is difficult to compensate for the respective disadvantages over a long period of time.

As another method for achieving both the improvement of fluidity and the dependence of charging on the environment, a method of adding hydrophobic amorphous titanium oxide fine particles to a toner has been proposed (Japanese Patent Laid-Open No. 5-204183). JP-A-5-727
No. 97). Amorphous titanium oxide fine particles are CVD
Can be obtained by hydrolyzing a metal alkoxide or a metal halide using the method described in Chemical Engineering, Vol. 18, No. 3, 303-307 (199)
2) ②.

However, since the amorphous titanium oxide fine particles have a large amount of water adsorbed inside the particles, they have a strong adhesive force to the photoreceptor, and the amorphous titanium oxide fine particles remain on the photoreceptor during transfer, and the remaining hard amorphous titanium oxide fine particles are Scratches on the photoconductor during cleaning,
In some cases, white spots on an image may be lost without being removed from the photoconductor by cleaning.

On the other hand, in a method of purifying titanium oxide fine particles via a wet method, a coupling agent is hydrolyzed in an aqueous medium, the surface of the titanium oxide fine particles is treated, and hydrophobicity is suppressed in a state where aggregation is suppressed. A method has been proposed in which titanium oxide fine particles are taken out and added to a toner (JP-A-5-188633).

In the hydrophobic titanium oxide fine particles treated with the silane coupling agent by this method, although the basicity of the titanium oxide is weak and causes a surface reaction with the silane coupling agent, the bond is formed between the bond between silica and aminosilane. The toner and the carrier collide due to stirring,
Alternatively, there is a disadvantage that the treating agent (silane coupling agent) of the titanium oxide fine particles added to the toner surface is easily peeled off by the rubbing between the toner and the blade or the sleeve, and as a result, the charging characteristics of the toner are greatly changed. . In addition, the amount of the hydroxyl group which is an active group is small, and the treatment amount of the silane compound which influences the charging may be limited, so that there is a problem that a high negative polarity cannot be obtained even at an initial stage.

As a developing method, a cascade method or the like has been used in the past, but at present, a magnetic brush method using a magnetic roll as a developer carrying carrier is mainly used. In the two-component magnetic brush development, a conductive magnetic brush (CMB) development using a conductive carrier and an insulating magnetic brush (IMB) development using an insulating carrier are known. Among these, in CMB development, charge is injected from a development roll due to low carrier resistance, and the carrier near the photoreceptor acts as a development electrode to increase the effective development electric field, resulting in sufficient transfer of toner. It has the characteristic that the reproducibility of the solid image is excellent. On the other hand, there is a problem that image defects such as a white line called a brush mark caused by charge injection from a developing roll and a transfer of a carrier to a photoreceptor called a carrier over easily occur.

On the other hand, there has been proposed a method of controlling the volume resistivity of a carrier to faithfully reproduce high image quality, especially halftone, solid black, and characters (Japanese Patent Application Laid-Open No. 56-1257).
No. 51, JP-A-62-267766, and JP-B-7-120086). In each of these methods, the resistance is adjusted according to the type and amount of the carrier coating layer, and although a target volume specific resistance is obtained initially and high image quality is exhibited, the carrier coating is performed by the stress in the developing machine. Peeling of the layer occurs, and the volume resistivity changes greatly. Therefore, it is difficult to exhibit high image quality for a long time.

In recent years, in particular, colorization has been rapidly progressing, and the required level of image quality has been increasing more and more. Solid images are particularly important in this color image quality, and the CMB development method is preferable to the IMB development method. On the other hand, C including durability including image output stability
There is a strong demand for further improvement in the performance of the conductive carrier used in the MB developing system.

As an improvement measure, an external additive to the toner is devised. The present inventors have previously described in Japanese Patent Application Laid-Open No. Hei 4-337778 a particle size of 20-8.
A method of externally adding 0 nm inorganic or organic spherical fine particles to a toner was proposed. Japanese Patent Application Laid-Open No. 6-75430 has proposed a method of externally adding 0.01 to 0.2 μm titanium oxide fine particles to a toner.

Japanese Patent Application Laid-Open No. 10-3177 proposes a method in which an additive is added to titanium compound fine particles obtained by reacting TiO (OH) ₂ with a silane compound. However, a single method such as the method of adding these external additives is not yet sufficient to sufficiently achieve high image quality and stable image quality over a long period of time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned state of the art. That is, an object of the present invention is to stably provide an appropriate negative charging property without lowering the triboelectric charging property of the toner, to improve the environment dependency, fluidity and anti-caking properties of the toner, (Image carrier), etc., image defects are less likely to occur, excellent image quality can be obtained, and high image quality, especially halftone, black solid, text, without significant changes in carrier volume resistivity over a long period of time An object of the present invention is to provide an electrostatic latent image developer capable of obtaining a faithful reproduction of the electrostatic latent image.

A second object of the present invention is to provide an image forming method capable of forming a full-color image particularly excellent in solid image reproducibility using the electrostatic latent image developer having the above advantages. It is in.

[0020]

SUMMARY OF THE INVENTION The present inventors have developed a toner comprising a carrier in a specific dynamic resistance region, a combination of a specific type of external additive and the like, and a compounding of an external additive within a specific range. It has been found that the above object can be achieved by the combination of the above, and the present invention has been completed. That is, in order to prevent image defects such as brush marks, carrier over, fog, etc., and to obtain a good and stable solid image, the resistance of the carrier needs to be within a desired range. In order to maintain stable image quality, it was found that the type of the specific external additive to the toner and the compounding ratio thereof were important, and the present invention was completed.

According to the present invention, there is provided an electrostatic latent image developer comprising a toner and a carrier, wherein the toner comprises a binder resin and a colorant. And at least two types of external additives of titanium compound fine particles and silica fine particles, and the mixing ratio (B / A) of the titanium compound fine particles (A) and the silica fine particles (B) in the external additives is And the dynamic electric resistance of the carrier under an electric field of 1 × 10 ⁺⁴ V / cm is 10 to 1 × 10 ⁺⁸ Ωc in the state of a magnetic brush.
m.

In the electrostatic latent image developer of the present invention, by appropriately adjusting the addition amount of the titanium compound fine particles and the silica fine particles as the external additives, it is possible to ensure the charge retention without environmental dependency. Can be. In addition, by using a carrier having a low resistance, the reproducibility of a solid image is excellent, and the charging characteristics are deteriorated when silica fine particles are used as an external additive of a toner. Can be suppressed. That is, the inconvenience when the titanium compound fine particles and the silica fine particles are used as an external additive at an appropriate ratio can be solved by using the low-resistance carrier defined in the present invention, and the object of the present invention is achieved at a high level. Can be achieved.

Here, in the electrostatic latent image developer of the present invention, the titanium compound fine particles are preferably fine particles of titanium oxide which has been subjected to a hydrophobic treatment.
H) Fine particles of a titanium compound obtained by reacting ₂ with a silane compound are preferred. The average primary particle diameter of the titanium compound fine particles is preferably in the range of 10 nm to 40 nm, and the average primary particle diameter of the silica fine particles is larger than the average primary particle diameter of the titanium compound fine particles, and is 40 nm to 40 nm. Preferably it is in the range of 100 nm.

On the other hand, the image forming method of the present invention for achieving the above object comprises at least a latent image forming step of forming an electrostatic latent image on a latent image carrier, and a developing process arranged opposite the latent image carrier. A developer layer forming step of forming a developer layer on the surface of the developer carrier, a developing step of developing an electrostatic latent image on the latent image carrier with the developer layer into a toner image, and developing the developed toner image. A transfer step of transferring onto a transfer material, wherein the four color toner images of cyan, magenta, yellow and black are stacked on the transfer material to form a full-color image. Among them, at least one color toner image is formed by the electrostatic latent image developer of the present invention. When the electrostatic latent image developer of the present invention is applied to full-color image formation, high image quality required for full-color image formation can be achieved, and particularly, solid image reproducibility is excellent.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The electrostatic latent image developer of the present invention comprises a toner and a carrier. A: Toner In the invention, the toner contains toner particles containing a binder resin and a colorant, and at least two types of external additives of titanium compound fine particles and silica fine particles.

[Toner Particles] In the present invention, the toner particles contain a binder resin and a colorant, and may contain other components as necessary. The colorant contained in the toner particles may be either a pigment or a dye, but is preferably a pigment having high coloring power and excellent in water resistance, light resistance, or solvent resistance.

In order to apply the electrostatic latent image developer of the present invention to full-color image formation, a color pigment (or dye) is required.
Must be used for toner particles. As such a pigment, C.I. I. Pigment Blue 15: 3, magenta coloring material, C.I. I. Pigment Red 57-1, 122, 238, as a yellow color material,
C. I. Pigment Yellow 180, 185, 17, 7
No. 4 is preferred as a black coloring material, and carbon black is preferred. Among them, as carbon black listed as a black coloring material,
Conventionally known ones can be used, but those having an average primary particle diameter of 35 nm or more and 50 nm or less as observed by electron microscopy are preferably used.

As the binder resin contained in the toner particles, those conventionally used as a binder resin for a toner are used without any particular limitation, and a polyester resin is preferably used from the viewpoint of fixability. The polyester resin constituting the binder resin is usually a conventionally known ethoxylated bisphenol type diol and propoxylated bisphenol type diol, and an aromatic dicarboxylic acid or an acid anhydride or an ester thereof as a main monomer component. Preferably, at least one selected from alkyl succinic acid or an acid anhydride or an ester thereof and alkenyl succinic acid or an acid anhydride or an ester thereof is further used in an amount of 5 to 25% based on the total amount of monomers. Mole percent, and the main monomers are ethoxylated bisphenol-type diol and propoxylated bisphenol-type diol, and aromatic dicarboxylic acid or its anhydride or ester thereof. Acid Its acid anhydride or its esters, and those produced by using alkenyl succinic acid or anhydride or ester thereof, at least one selected from as a minor component.

Further, in order to enlarge the fixing latitude, it is desirable to add a monomer capable of forming a crosslink such as a trihydric or higher polyhydric alcohol and / or a trivalent or higher polyhydric carboxylic acid.

The ethoxylated bisphenol type diol (polyoxyethylene bisphenol type diol) and the propoxylated bisphenol type diol (polyoxypropylene bisphenol type diol) are ethoxylated and propoxylated bisphenols, which are bisphenols. Examples thereof include those having 2 to 3 moles of oxyethylene or oxypropylene per mole, and are represented, for example, by the following general formula (I).

Formula (I)

Embedded image

(Wherein, R represents an ethylene group or a propylene group, x and y are integers of 1 or more, and x +
y is in the range of 2-7. )

As a specific example, polyoxyethylene (2,2) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxyethylene (1,5) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene ( 6) -2,
Examples thereof include 2-bis (4-hydroxyphenyl) propane and polyoxypropylene (2,2) -2,2-bis (4-hydroxy-2,6-dichlorophenyl) propane. These etherified bisphenol-type diols can be produced by directly adding ethylene oxide or propylene oxide to diphenol, or by reacting olefin halohydrin with diphenol. The ratio of the ethoxylated bisphenol type diol to the propoxylated bisphenol type diol is 1: 1.
It is preferably in the range from 0 to 10: 1, especially 1: 4 to 4: 1.

As other alcohol components, if necessary, ethylene glycol, propylene glycol,
1,4-butanediol, 1,5-pentanediol,
Use aliphatic polyols such as 1,6-hexanediol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol, and alicyclic alcohols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol. be able to.

On the other hand, examples of the aromatic dicarboxylic acid include aromatic carboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid. Further, as the esters thereof, low molecular alcohol esters of the above dicarboxylic acids, for example, dimethyl terephthalate, diethyl terephthalate,
Dimethyl isophthalate and the like can be mentioned.

Examples of the alkyl succinic acid or acid anhydride or ester thereof and the alkenyl succinic acid or acid anhydride or ester thereof include, for example, n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutyric acid Tenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, anhydrides thereof, lower alkyl esters and the like. .

Examples of the trivalent or higher polycarboxylic acid or its anhydride, or its lower alkyl ester include:
1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5
7-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetra Carboxylic acid, trimesic acid, pyromellitic acid, and acid anhydrides or lower alkyl ester compounds thereof, and the like, particularly trimellitic acid, trimesic acid, pyromellitic acid, or acid anhydrides thereof, methyl ester compounds, Ethyl ester compounds are preferred.

Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetol, 1,4
-Sorbitan, pentaeristol, dipentaeristol, tripentaeristol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl- 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3
For example, 5-trihydroxymethylbenzene is used.

The ratio of the trivalent or higher polycarboxylic acid or its anhydride, or its lower alkyl ester, and the trivalent or higher alcohol component to at least one kind of the total monomer is 10%. Preferably, it is less than mol%. The amount added is adjusted so as to be in the following molecular weight range.

The polyester resin used as the binder resin has a molecular weight range of THF (tetrahydrofuran) solvent-soluble component having a weight average molecular weight of Mw: 5.
2,000 to 150,000, preferably 8,000
More preferably, it is set to 120,000 or less. The hydroxyl value of the polyester resin used as the binder resin is preferably less than 30 mgKOH, and the acid value is
Preferably it is less than 20 mg KOH.

As other components contained in the toner particles as required, a charge control agent, a release agent and the like can be mentioned. These are added as needed as long as various properties such as color reproducibility and transparency of the toner are not affected. Specifically, examples of the charge controlling agent include a chromium azo dye, an iron azo dye, an aluminum azo dye, a salicylic acid metal complex, and an organic boron compound. Further, as the release agent, low molecular weight propylene,
Examples include polyolefins such as low molecular weight polyethylene, paraffin waxes, natural waxes such as candelilla wax, carnauba wax, montan wax, and derivatives thereof.

The toner particles can be produced by any conventionally known method such as a pulverization method or a polymerization method by suspension polymerization or emulsion polymerization. In the present invention, the volume average particle diameter of the toner particles is 3 to 15 μm.
And more preferably in the range of 4 to 10 μm. When the volume average particle size is less than 3 μm, the developing efficiency of the toner on the photoconductor and the transfer efficiency from the photoconductor to the transfer medium are apt to decrease, and a clear image may not be formed. Exceeding this is not preferable because the shape of the dots, which are the units for forming an image, tends to be lost, and the reproducibility of the fixed image tends to deteriorate.

[Titanium Compound Fine Particles] The titanium compound fine particles of the present invention generally contain titanium oxide fine particles as a main component. As the titanium oxide, conventionally known types such as anatase type and rutile type can be used,
Preferably, the anatase type is selected. The titanium compound fine particles are preferably subjected to a hydrophobic treatment, and any conventionally known method can be employed as the method of the hydrophobic treatment. For example, there may be mentioned a wet production method in which a hydrophobic agent is added to a solution dispersed in a solution, and a dry production method in which a hydrophobic agent is added while stirring. Examples of such hydrophobizing agents include conventionally known silane coupling agents, silicone oils, and surfactants.

The titanium compound fine particles are more preferably a titanium compound obtained by reacting TiO (OH) ₂ with a silane compound (a compound mainly composed of titanium oxide, hereinafter referred to as “specific titanium oxide”). ).
TiO (OH) ₂ can be generally produced by a sulfuric acid method (wet method) using ilmenite ore. Hereinafter, the reaction according to the method is shown by a chemical reaction formula. FeTiO ₂ + 2H ₂ SO ₄ → FeSO ₄ + TiOSO ₄ +
2H ₂ O TiOSO ₄ + 2H ₂ O → TiO (OH) ₂ + H ₂ SO ₄

Then, a silane compound is added in a TiO (OH) ₂ state, a part or all of the OH group is treated, and this is filtered, washed, dried, and pulverized to obtain a crystalline titanium oxide by a conventional method. Specific titanium oxide having a lower specific gravity can be obtained as compared with (obtained by firing TiO (OH) ₂ ). That is, when the reaction is performed in a solution as described above, TiO (OH) ₂ is treated with a silane compound during its hydrolysis. As a result, TiO (O
H) Titanium oxide produced from ₂ is surface-treated with a silane compound in the state of primary particles. Therefore, it is possible to obtain specific titanium oxide in a primary particle state without aggregation.

In the present invention, it is particularly preferable to use the specific titanium oxide obtained as described above as titanium compound fine particles. By using the specific titanium oxide in the present invention, extremely good chargeability, environmental stability,
Has fluidity, anti-caking properties, and stable negative charge.
Further, it is possible to provide a developer excellent in image quality maintenance.

In the above reaction, the fine adjustment of the specific gravity and the negative chargeability of the specific titanium oxide can be controlled by the type and the treatment amount of the silane compound. That is, when the treatment amount of the silane compound is increased, specific titanium oxide having a small specific gravity and a high charge-imparting ability is obtained, while when the treatment amount of the silane compound is decreased, specific titanium oxide having a large specific gravity and a low charge-imparting ability is obtained.

In the present invention, it is preferable to control the specific gravity of the specific titanium oxide to 2.8 to 3.6. In order to make the specific gravity of the specific titanium oxide less than 2.8, it is necessary to add an excessive amount of the silane compound, whereby the reaction between the silane compounds partially occurs, an aggregate is easily formed, and the desired fluidity is obtained. Can not be obtained. If the specific gravity of the specific titanium oxide exceeds 3.6, it is difficult to disperse the specific titanium oxide on the surface of the toner particles at the time of blending. The particles move to the concave portions of the particles to reduce the desired fluidity and chargeability, or the specific titanium oxide at the convex portions of the toner particles is easily released, and in a two-component developer, the released specific titanium oxide moves to the carrier surface. As a result, the volume resistivity of the carrier is greatly changed, and it becomes impossible to obtain excellent image quality over a long period of time.

As the silane compound, those which are water-soluble can be used. As such a silane compound, a chemical structural formula R _a SiX _4-a (where a is an integer of 0 to 3;
Represents a hydrogen atom, an organic group such as an alkyl group or an alkenyl group, and X represents a hydrolyzable group such as a chlorine atom, a methoxy group or an ethoxy group. ) Can be used, and any type of chlorosilane, alkoxysilane, silazane, and special silylating agent can be used.

Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane Silane, methyltriethoxysilane, dimethyldiethoxysilane,
Phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (trimethylsilyl) urea, tert-butyldimethylchlorosilane , Vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane can be exemplified as typical examples. In the present invention, the silane compound is particularly preferably dimethyldimethoxysilane, hexamethyldisilazane, methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, or the like.

The amount of the silane compound to be treated is generally from 1 to 25 parts by weight based on 100 parts by weight of TiO (OH) _2.
0 parts by weight, preferably in the range of 50 to 200 parts by weight. After the drying, the composite treatment may be performed using another compound. The average primary particle diameter of the titanium compound fine particles containing the specific titanium oxide is preferably from 10 to 40 nm, more preferably from 15 to 35 nm, from the viewpoints of imparting chargeability, cleaning the photoconductor, and toner fluidity.

[Silica Fine Particles] The silica fine particles used in the present invention may be any of the conventionally known silica fine particles. In particular, the average primary particle size is preferably the average primary particle size of the titanium compound fine particles used in the present invention. Larger and preferably 40 nm to 100 nm.
More preferably, it is 80 nm. In addition, the shape of the silica fine particles is particularly preferably spherical. The silica fine particles used in the present invention may be produced by any conventionally known method such as a wet method and a dry method. In addition, various surface treatments (hydrophobizing treatment or the like) may be applied to the surface of the silica fine particles for the purpose of charge control or the like.

[Addition of External Additives] In the production of the toner according to the present invention, at least two types of external additives, ie, the fine titanium compound particles and the fine silica particles, are added to the toner particles and mixed. For example, it can be performed by a known mixer such as a V-type blender, a Henschel mixer or a Loedige mixer.

At this time, the mixing ratio (B / A) of the titanium compound fine particles (A) and the silica fine particles (B) is 1
It is indispensable to set the range to at least 3 and at most 3, and it is preferable to set the range to at least 1 and at most 2. This mixing ratio (B /
If A) is less than 1, the charge retention of the finally obtained electrostatic latent image developer deteriorates, and if it exceeds 3, the environmental charge ratio (charging under high-temperature high-humidity environment and low-temperature low-humidity environment) The greater the distance between the two, the worse the environmental charging ratio.) The addition amount of the two types of external additives, the titanium compound fine particles and the silica fine particles, is preferably in the range of 0.5 to 3 parts by weight, more preferably 0.6 to 1.5 parts by weight, based on 100 parts by weight of the toner particles. Is more preferable.

Further, various other external additives may be added together with at least two types of external additives of the titanium compound fine particles and the silica fine particles as required. Examples of these other external additives include other fluidizing agents, and cleaning aids or transfer aids such as polystyrene fine particles, polymethyl methacrylate fine particles, and polyvinylidene fluoride fine particles. The total amount of the external additives is preferably in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the toner particles in view of the balance between fluidity, particle diameter, and specific gravity.

B: Carrier In the present invention, the carrier is 1 × 10⁺⁴V / cm
The dynamic electric resistance under the field is 1 in the state of the magnetic brush.
0-1 × 10⁺⁸Ωcm range. 1 × 10 ⁺⁴V / c
Specifies the measurement in the state of the magnetic brush under an electric field of m
The reason is that we are aware of the resistance in actual use conditions.
is there.

The dynamic electric resistance of the carrier is 10 Ωc.
If it is less than m, the conductivity is too high, and image defects such as brush marks and carrier over caused by charge injection from the developing roll and the like are likely to occur. On the other hand, if the dynamic electric resistance of the carrier exceeds 10 ⁺⁸ Ωcm, the reproducibility of a solid image becomes insufficient, and the charging characteristics of the toner used in the present invention deteriorate.

The dynamic electric resistance of the carrier is 1
It is preferably in the range of 0 ² ~10 ⁷ Ωcm, 10 ²
More preferably, it is in the range of 10 to 10 ⁶ Ωcm. In the present invention, the dynamic electric resistance of the carrier is determined as follows.

A flat electrode having an area of 3 cm ² is opposed to a developing roll having a diameter of 4 cm and a length of 10 cm in the axial direction at an interval of 2.5 mm, and a carrier to be measured is placed on the developing roll facing the flat electrode. To form a magnetic brush. At this time, the weight of the carrier per unit area is about 40.
mg / cm ² . While rotating the developing roll at a rotation speed of 120 rpm, a voltage is applied between the developing roll and the plate electrode, and a current flowing at that time is measured. From the obtained current-voltage characteristics, the electrical resistance is obtained using the equation of Ohm's law. The electric resistance thus determined is the dynamic electric resistance of the carrier according to the present invention.

It is well known that the relationship between the applied voltage E and the current density J at this time generally has a relationship of log J∝E ^1/2 (eg, Japanese Journa).
lof Applied Physics 19, 1
No. 2, P2413-). When the electric resistance is low as in the carrier used in the present invention, a large electric current may flow in a high electric field of 1000 V / cm or more, and measurement may not be performed.
In such a case, three or more points are measured in a low electric field and extrapolated to an electric field of 10 ⁴ V / cm by the least squares method using the above relational expression.

The carrier used in the present invention may be any carrier as long as it exhibits the above-mentioned dynamic electric resistance. Usually, however, a resin coating layer is formed on a magnetic carrier core.

As the carrier core used in the present invention, any of those conventionally known can be used. Particularly preferred is a carrier core made of low-resistance ferrite or magnetic powder-dispersed resin. As other carrier cores, for example, iron powder and magnetite are known, but in the case of iron powder, the specific gravity is large, so that the toner and the external additive tend to adhere, and therefore, the stability is inferior to ferrite. In the case of magnetite, resistance control is difficult and the latitude of electric resistance is narrow.On the other hand, in the case of ferrite, various electric resistances are controlled by controlling the reduction time at a certain temperature in a hydrogen stream after firing. This is particularly preferable because the following is obtained. Further, in the problem of harmful heavy metals (especially in the problem of waste), copper and the like are not preferred, and those which are constituent metal elements of manganese and iron are preferably used.

The volume average particle diameter of the carrier core composed of magnetic particles such as ferrite is preferably 10 to 10
0 μm, more preferably 20 to 80 μm. If the volume average particle diameter is smaller than 10 μm, the developer is liable to be scattered from the developing device, and is developed together with the toner at the time of development to adversely affect an image. On the other hand, 100
If it is larger than μm, the toner cannot be supplied faithfully with respect to the development potential on the photoconductor, and it is difficult to obtain good image quality.

The carrier core made of the magnetic powder-dispersed resin is
Powders of a magnetic material such as ferrite, iron powder, and magnetite are dispersed in a thermoplastic resin or a thermosetting resin. Specific examples of such thermoplastic resins and thermosetting resins include polyolefin resins, polyester resins, polyurethane resins, polycarbonate resins, melamine resins, phenol resins, and the like.

The particle diameter of the magnetic material powder used here is preferably in the range of 0.01 to 10 μm,
The range of about 5 μm is more preferable. The volume average particle diameter of the carrier core composed of a magnetic powder-dispersed resin in which these are dispersed in a resin is preferably 10 to 1 as in the case of the magnetic particles.
It is 00 μm, more preferably 20 to 80 μm.

Further, as described above, the carrier core is usually provided with various known resin coating layers on its surface.
Although the carrier is constituted, an intermediate layer made of a silane coupling agent, a titanate coupling agent, or the like may be provided between the carrier core and the resin coating layer. Specifically, vinyltrimethoxysilane, vinyltriethoxysilane, tris- (β-methoxyethoxy) vinylsilane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β -(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, β-mercaptoethyltrimethoxysilane, γ-chloropropyltrimethoxysilane, isopropyltristearoyl titanate, isopropylmethacrylisostearoyl titanate, etc. Known compounds can be mentioned.

Examples of the resin for forming the resin coating layer include known resins such as vinyl resins such as acrylic resins and styrene-acrylic resins, rosin resins, polyester resins, silicone resins and urethane resins. be able to.

In producing the carrier used in the present invention, the above resin may be coated on the surface of the carrier core by, for example, a dipping method in which the carrier core is dipped in a coating layer forming solution, A spray method of spraying a solution onto the carrier core surface, a fluidized bed method of spraying a coating layer forming solution in a state where the carrier core is suspended by flowing air, and applying the carrier core and the coating layer forming solution in a kneader coater. Known methods such as a kneader coater method of removing the solvent while mixing can be used.

The solvent used in the coating layer forming solution is
Any type can be used as long as the resin for forming the resin coating layer can be dissolved. For example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used. Further, a mixed form of these solvents may be used. In the coating resin solution, conductive powder particles are preferably dispersed as a resistance adjuster, and metal oxide powder is used as the conductive powder. The conductive powder particles preferably have an electric resistance of 10 ⁶ Ωcm or less.

The shape of the conductive powder particles may be spherical, fiber (needle), or scale. The size of the conductive powder particles depends on the carrier core size to be used, but considering the maximum length of the particle diameter shape, it is preferable to use those having a size of 3 μm or less, more preferably 1 μm or less,
Considering the volume average particle size, it is preferable to use one having a particle size of 0.01 to 0.8 μm, more preferably 0.03 to 0.8 μm.
0.3 μm.

Examples of the material of the conductive powder particles include simple particles such as zinc oxide, tin oxide, titanium oxide, iron oxide, and titanium black; and fine particles such as titanium oxide, zinc oxide, aluminum borate, potassium titanate, and barium sulfate. A composite material whose surface is coated with a conductive metal oxide may be used.

Examples of the conductive metal oxide include a metal oxide doped with antimony (for example, antimony-doped tin oxide) and an oxygen-deficient metal oxide (for example, oxygen-deficient tin oxide). However, in the oxygen-deficient type, it is preferable to use an antimony-doped type because water is relatively easily adsorbed to the oxygen-deficient portion. There is no particular limitation as long as a desired electrical resistance can be imparted to the resin coating layer. Each may be used alone or in combination.

The content of the conductive powder particles may be adjusted so that the dynamic electric resistance of the carrier falls within the range specified in the present invention. Specifically, a resin coating layer formed on the surface of the carrier core is used. 10 to 60% by volume, preferably 30 to 6%
It is blended with the coating resin solution so as to be 0% by volume. 10
When the amount is less than 60% by volume, the resistance of the resin coating layer does not decrease to a desired value, and when the amount is more than 60% by volume, the resin coating layer tends to become brittle. Also, dispersion stability becomes difficult.

As a method of dispersing the conductive powder particles in the resin solution for coating, a known method can be applied, but a medium mill is preferably used. The resin solid content concentration in the coating resin solution is preferably 20% by weight or less. 20
If the content is more than 10% by weight, it is difficult to disperse and stabilize the conductive powder particles when producing the coating resin solution.

In recent years, since the configuration of a developing device for a two-component developer has been reduced in size, and the copying and printing speeds have been increasing, the magnetic properties of the carrier have to be set higher than before. Therefore, the value of the magnetic characteristic is 1
At a magnetic field σ ₁₀₀₀ value of 000K Oersted,
Those in the range of 90 Am ² / Kg can be preferably used. If the magnetic properties of the carrier are less than 60 Am ² / Kg, BCO (a phenomenon in which the carrier is developed together with the toner on the photoreceptor) occurs, deteriorating the print image quality, and causing 90 A.
If it exceeds m ² / Kg, the magnetic brush becomes hard, causing a brush mark and deteriorating the print quality.

C: Production of Electrostatic Latent Image Developer The electrostatic latent image developer of the present invention is produced by mixing the toner and the carrier as described above. The mixing ratio of the toner and the carrier is preferably 3 to 12 parts by weight, more preferably 5 to 8 parts by weight based on 100 parts by weight of the carrier, from the viewpoint of chargeability of the developer. Is more preferable.

D: Image Forming Method The electrostatic latent image developer of the present invention obtained as described above is
At least, a latent image forming step of forming an electrostatic latent image on the latent image carrier, and a developer layer forming step of forming a developer layer on the surface of the developer carrier disposed against the latent image carrier. ,
A developing step of developing the electrostatic latent image on the latent image carrier into a toner image using the developer layer; and a transfer step of transferring the developed toner image onto a transfer material, the developer layer comprising: Is used as a developer for forming

In particular, in an image forming method for forming a full-color image by laminating four color toner images of cyan, magenta, yellow and black on a transfer material,
If at least one toner image of the four colors is formed by the electrostatic latent image developer of the present invention,
The high image quality required for full-color image formation, especially the reproducibility of a solid image is obtained. Needless to say, it is desirable that the toner images of all four colors be formed with the electrostatic latent image developer of the present invention.

[0079]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following description, all “parts” mean “parts by weight” unless otherwise specified.

[Example 1] 1. Using the preparation of the external additive ilmenite <Preparation of a titanium compound fine particles A> as ore, to separate the iron dissolved in sulfuric acid, TiOSO ₄
Was hydrolyzed to form TiO (OH) ₂ (wet sedimentation method). In the process, the mixture was subjected to dispersion adjustment for hydrolysis and nucleation and washing with water.

80 parts of isobutyltrimethoxysilane was added dropwise to 100 parts of TiO (OH) ₂ dispersed in 500 ml of water while stirring at room temperature. Then, it was filtered and water washing was repeated. The thus-obtained titanium compound surface-treated with isobutyltrimethoxysilane was dried at 180 ° C. and pulverized for 5 minutes using a pin mill.
0 nm titanium compound fine particles A (specific gravity 3.2) were obtained.

<Preparation of Silica Fine Particles B> 100 parts of silica fine particles (OX-50, manufactured by Nippon Aerosil Co., Ltd.) were placed in a Henschel mixer heated to about 70 ° C. in a vessel, and the peripheral speed of the blade was set to 200 m / sec. And stirred. A solution of 30 parts of methanol and 5 parts of hexyltrimethoxysilane (LS-3130: manufactured by Shin-Etsu Chemical Co., Ltd.) are sprayed little by little, and the whole amount is sprayed. Thereafter, stirring was continued until methanol was vaporized, then cooled, a sample was taken out, placed in a drier, and cured at about 130 ° C. After cooling, crushing was repeated several times with a pin mill to obtain silica external additive B. When this was observed with an electron microscope, the average primary particle size was 43 nm.

2. Preparation of toner particles <Resin production example>-Polyoxyethylene (2,2) -2,2-bis (4-
Hydroxyphenyl) propane 0.7 mol polyoxypropylene (2,2) -2,2-bis (4
-Hydroxyphenyl) propane 1.6 mol Terephthalic acid 1.4 mol n-Dodecenyl succinic acid 0.7 mol Trimellitic acid 0 .2 mol

The above raw material compound was placed in a two-liter glass four-necked flask, and a stir bar, a condenser, a nitrogen gas inlet tube, a thermometer were set, and a mantle heater was set. After the inside of the reaction vessel was replaced with nitrogen gas, 1 g of dibutyltin oxide was added, and the reaction was carried out at 180 ° C. in the first half and under reduced pressure at 220 ° C. in the latter half under a nitrogen stream while heating with a mantle heater. The degree of polymerization was monitored from the softening point according to the ring and ball softening point measurement method (JIS-K2531), and the reaction was terminated when the softening point reached 140 ° C. After the completion of the reaction, the resultant was gradually cooled to room temperature. The glass transition point Tg of the obtained resin C was 67 ° C.

<Production Example of Flushing Cyan Pigment> To 100 parts of the resin C obtained above, 60 parts of a cyan pigment (CI pigment blue 15: 3) having a water content of 30% by weight was added, and the mixture was heated to 120 ° C. 1kgf with a pressure kneader
/ Cm ² while applying pressure at a pressure of 20 cm / s
By rotating at ec, melt-kneading and water removal were repeated to obtain a flushing cyan pigment having a pigment content of 30% by weight.

<Production of Toner Particles (Cyan)> ・ The above-mentioned flushing cyan pigment... 16.7 parts ・ Resin C... 83.7 parts by weight After melt-kneading, then cooling, coarsely pulverizing, pulverizing with a jet mill, and performing classification operation to obtain a cyan pigment content of 4% by weight, a volume average particle diameter D _V = 6.8 μm, and a volume particle size distribution D
₁₆ (vol) / D ₈₄ (vol) = 1.6 toner particles (cyan) were obtained.

3. Manufacture of toner To the toner particles (cyan) obtained above, as an external additive,
The titanium compound fine particles A and the silica fine particles B are added such that the mixing ratio B / A (weight ratio) becomes 1 and the total amount of the external additives becomes 1.2 parts with respect to 100 parts of the toner particles. The resulting mixture was mixed with a Henschel mixer to obtain cyan toner 1.

4. Production of Carrier <Example of Production of Resin for Forming Coating Layer> 85.0 parts of methacrylic acid methyl ester was dissolved in 300 parts of toluene, and a polymerization initiator AIBN: 1.64 parts (10 mmol) was added. The reaction was performed for 60 hours. After completion of the reaction, the resultant was dispersed in methanol and precipitated, and this was collected by filtration and dried in vacuo. When the molecular weight of the obtained polymer (resin C for forming a coating layer) was measured by gel permeation chromatography, the weight average molecular weight Mw was 50,000.

<Manufacture of Carrier-1> Toluene 100 parts Resin C for forming a coating layer 9 parts Conductive powder: Tin oxide-based conductive powder (Pastran Type-I)
V, 1 × 10 ⁴ Ω · cm, volume average particle diameter 100 nm:
Mitsui Kinzoku Co., Ltd. 27 parts Beads for media mill (diameter 1 mm) 200 parts

After the above components were placed in a sand mill and dispersed, the medium mill was removed to prepare Dispersion-1. 18.8 parts of the obtained dispersion-1 and magnetite (MX030A:
Volume average particle diameter 50 μm, σ ₁₀₀₀ = 82.3 Am ² / K
g: manufactured by Fuji Electric Chemical Co., Ltd.) and 100 parts thereof were placed in a vacuum degassing kneader, mixed at a tank temperature of 50 ° C., and 3
The mixture was stirred for 0 minutes, and the surface of the magnetite was coated while removing the solvent to obtain Carrier-1. The thickness of the resin coating layer was 0.8 μm.

The dynamic electric resistance of the carrier-1 was measured by the method described above and found to be 5 × 10 ⁵ Ω · cm (extrapolated to an electric field of 10 ⁴ V / cm). The magnetic properties of the carrier were measured and found to be 82 Am ² / Kg.

[0092] 5. Production of Electrostatic Latent Image Developer The toner thus obtained, 1: 6 parts, and carrier-1: 100 parts were mixed in a V-type blender, and the electrostatic latent image developer of Example 1 was mixed. Was manufactured.

6. Evaluation Method <Evaluation of Charging Characteristics> The above toner 1: 6 parts and carrier
1: 100 parts and a glass reagent bottle (size 20 cc)
The lids were opened in a low-temperature and low-humidity (10 ° C. 20% RH) environment and a high-temperature and high-humidity (30 ° C. 80% RH) environment, respectively, and seasoned for one day and night. Thereafter, the lid was closed, blending was performed for 5 minutes using a turbula mill, and the charge amount was measured using a blow-off tribo apparatus. From the obtained charge amount value, the environmental charge amount ratio was calculated by the following equation. Environment charge amount ratio = (charge amount under high temperature and high humidity environment) /
(Charge amount under low-temperature and low-humidity environment) The following evaluation criteria were used to evaluate the obtained charge amount and environmental charge ratio. The results are summarized in Table 1 below.

(Evaluation standard of charge amount) ○: Within the range of 20 to 40 μq / g ×: Out of the range of 20 to 40 μq / g (Environmental charge amount ratio) ：: 0.5 to 1.0 Less than 5

<Evaluation of Image Quality> The obtained electrostatic latent image developer of Example 1 was converted to an A-Color 635 modified machine (in which voltage control and bias control were varied so that development conditions could be properly adjusted). The image quality was evaluated. The image included a solid image and a character image having an image area ratio of 30 to 100%. The test environment was normal temperature and normal humidity (25 ° C., 60% RH). The results are summarized in Table 1 below. The specific evaluation contents are as follows.

(Evaluation of Initial Image Quality Characteristics) The image samples at the initial stage of development were subjected to a sensory evaluation according to the following evaluation criteria. ：: Uniform and stable image quality over the edge portion of the solid image and the other entire surface. Δ: No brush mark, but noticeable image omission. X: Brush mark or partial image omission (toner is not developed) is conspicuous, and the image quality is rough.

(Evaluation of Image Quality Maintainability) A continuous durability test was performed on up to 30,000 sheets, and the image quality of the obtained image was sensory evaluated at each stage of 1,000, 10,000, and 30,000 sheets. . The image quality was evaluated by sensory evaluation based on the following evaluation criteria, focusing particularly on fog, white streaks, and the like. ：: The image quality hardly deteriorates or is inconspicuous. ×: Deterioration of image quality can be clearly determined.

[Example 2] In "3. Production of toner" in Example 1, the mixing ratio B / A (weight ratio) of the external additive was 2
A toner 2 was obtained in the same manner as in Example 1, except that the following conditions were satisfied. An electrostatic latent image developer was prepared in the same manner as in Example 1 except that toner 2 in “4. Production of electrostatic latent image developer” and “5. Manufacture and each evaluation were performed. The results are summarized in Table 1 below.

[Example 3] In "3. Production of toner" in Example 1, the mixing ratio B / A (weight ratio) of the external additive was 3
A toner 3 was obtained in the same manner as in Example 1, except that the following conditions were satisfied. An electrostatic latent image developer was prepared in the same manner as in Example 1 except that toner 3 in “4. Production of electrostatic latent image developer” and “5. Manufacture and each evaluation were performed. The results are summarized in Table 1 below.

Comparative Example 1 The procedure of Example 1 was repeated, except that the mixing ratio B / A (weight ratio) of the external additive was changed to 0.8 in “3. Production of toner” in Example 1. In the same manner as in the above, a toner 4 was obtained. Toner 1 in “4. Production of electrostatic latent image developer” and “5.
An electrostatic latent image developer was manufactured in the same manner as in Example 1 except that toner 4 was used, and each evaluation was performed. The results are summarized in Table 1 below.

Comparative Example 2 Example 1 was repeated except that the mixing ratio B / A (weight ratio) of the external additive was changed to 3.3 in “3. Production of toner” of Example 1. In the same manner as in the above, Toner 5 was obtained. Toner 1 in “5. Production of electrostatic latent image developer” and “6.
An electrostatic latent image developer was manufactured in the same manner as in Example 1 except that toner 5 was used, and each evaluation was performed. The results are summarized in Table 1 below.

[Example 4] In Example 1, "Production of carrier-1" in "4. Production of carrier" was replaced with "Production of carrier-2" below, and the other conditions were the same as in Example 1. Carrier-2 was obtained.

<Manufacture of Carrier-2> Toluene 100 parts Resin C for forming a coating layer 9 parts Conductive powder: Tin oxide-based conductive powder (Pastran Type-I)
V, 10Ω · cm, volume average particle diameter 100 nm: manufactured by Mitsui Kinzoku Co., Ltd. 13 parts Conductive powder: acicular conductive titanium oxide (FT1000, 3Ω)
・ Cm: Ishihara Sangyo Co., Ltd. ・ ・ ・ ・ ・ 17 parts ・ Bead for media mill (diameter 1mm) ・ ・ ・ ・ ・ ・ ・ 200 parts

After the above components were placed in a sand mill and dispersed, the medium mill was removed to prepare Dispersion-2. The obtained dispersion liquid-2: 20 parts and magnetite (MX030A: volume average particle diameter 50 μm, σ ₁₀₀₀ = 82.3 Am ² / Kg:
100 parts) and a vacuum degassing type kneader, and mixed at a tank temperature of 50 ° C., stirred for 30 minutes while reducing the pressure, and coating the magnetite surface while removing the solvent to obtain a carrier. 2 was obtained. The thickness of the resin coating layer is 1μ
m.

The dynamic electric resistance of this carrier-2 was measured by the above-mentioned method and found to be 2 × 10 ¹ Ω · cm (extrapolated to an electric field of 10 ⁴ V / cm). In addition, carrier
When the magnetic characteristics of No. ² were measured, 82.1 Am ² / Kg
Met. The electrostatic latent image development was performed in the same manner as in Example 1 except that the carrier-1 in “5. Production of an electrostatic latent image developer” and “6. An agent was manufactured and each evaluation was performed. The results are summarized in Table 1 below.

[Example 5] In the same manner as in Example 1 except that <Manufacture of Carrier-1> in "4. Manufacture of Carrier" in Example 1 was replaced with <Manufacture of Carrier-3> described below. Carrier-3 was obtained.

<Manufacture of Carrier-3> Toluene 100 parts Resin C for forming a coating layer 9 parts Conductive powder: tin oxide-based conductive powder (Pastran Type-I)
V, 1 × 10 ⁴ Ω · cm, volume average particle diameter 100 nm:
・ 15 parts by weight ・ Beads for media mill (diameter 1mm) ・ ・ ・ ・ ・ 200 parts

After the above components were placed in a sand mill and dispersed, the medium mill was removed to prepare Dispersion-3. 18.8 parts of the obtained dispersion-3: magnetite (MX030A:
Volume average particle diameter 50 μm, σ ₁₀₀₀ = 82.3 Am ² / K
g: manufactured by Fuji Electric Chemical Co., Ltd.) and 100 parts thereof were placed in a vacuum degassing kneader, mixed at a tank temperature of 50 ° C., and 3
The mixture was stirred for 0 minutes, and the surface of magnetite was coated while removing the solvent, to obtain Carrier-3. The thickness of the resin coating layer is
It was 0.8 μm.

The dynamic electric resistance of the carrier-3 was measured by the above-mentioned method and found to be 5 × 10 ⁷ Ω · cm (extrapolated to an electric field of 10 ⁴ V / cm). In addition, carrier
When the magnetic characteristics of No. 3 were measured, 82.2 Am ² / Kg
Met. The electrostatic latent image development was performed in the same manner as in Example 1 except that the carrier-1 in “5. Production of electrostatic latent image developer” and “6. Evaluation method” in Example 1 was changed to carrier-3. An agent was manufactured and each evaluation was performed. The results are summarized in Table 1 below.

Comparative Example 3 The procedure of Example 1 was repeated, except that “Production of Carrier-1” in “4. Production of Carrier” in Example 1 was changed to “Production of Carrier-H1” below. Carrier-H1 was obtained.

<Manufacture of Carrier-H1> Toluene 100 parts Resin C for forming a coating layer 7 parts Conductive powder: Tin oxide-based conductive powder (Pastran Type-I)
V, 1 Ω · cm, volume average particle diameter 100 nm: Mitsui Kinzoku Co., Ltd. 10 parts Conductive powder: acicular conductive titanium oxide (FT1000, 10
Ω · cm: Ishihara Sangyo Co., Ltd.) 25 parts

After the above components were placed in a sand mill and dispersed, the medium mill was removed to prepare Dispersion-4. The obtained dispersion-4: 20 parts and magnetite (MX030A: volume average particle diameter 50 μm, σ ₁₀₀₀ = 82.3 Am ² / Kg:
100 parts) was placed in a vacuum degassing kneader, mixed at a tank temperature of 50 ° C., and reduced in pressure to 30 parts.
After stirring for minutes, the surface of the magnetite was coated while removing the solvent to obtain Carrier-H1. The thickness of the resin coating layer is
It was 0.5 μm.

The dynamic electric resistance of the carrier H1 has already been described.
5 × 10 ⁰Ω · cm
(10^FourExtrapolated to an electric field of V / cm). In addition, carrier
When the magnetic properties of H1 were measured, it was 82.2 Am^Two/ K
g. Example 1 "5. Production of electrostatic latent image developer"
And Carrier-1 in “6.
Except for using the rear H1, static electricity was set in the same manner as in Example 1.
An electrostatic latent image developer was manufactured, and each evaluation was performed. Result is
The results are shown in Table 1 below.

[Comparative Example 4] In the same manner as in Example 1 except that <Manufacture of Carrier-1> in “4. Carrier-H2 was obtained.

<Manufacture of Carrier-H2> Toluene 100 parts Resin C for forming a coating layer 9 parts Conductive powder: tin oxide-based conductive powder (Pastran Type-I)
V, 1 × 10 ⁴ Ω · cm, volume average particle diameter 100 nm:
5 parts by weight-Beads for media mill (diameter 1 mm)-200 parts by weight

After the above components were placed in a sand mill and dispersed, the medium mill was removed to prepare Dispersion-4. The obtained dispersion-4: 18.8 parts by weight and ferrite (EFC-50
B: volume average particle diameter 50 μm, σ ₁₀₀₀ = 63.7 Am ²
/ Kg: manufactured by Powder Tech Co., Ltd.) and 100 parts by weight were put into a vacuum degassing type kneader, mixed at a tank temperature of 50 ° C., and stirred for 30 minutes under reduced pressure to coat the ferrite surface while removing the solvent. And Carrier-H2. The thickness of the resin coating layer was 0.8 μm.

The dynamic electric resistance of the carrier H2 has already been described.
6 × 10 ⁸Ω · cm
(10^FourExtrapolated to an electric field of V / cm). In addition, carrier
When the magnetic properties of H2 were measured, it was 63.4 Am^Two/ K
g. Example 1 "5. Production of electrostatic latent image developer"
And Carrier-1 in “6.
Except that rear-H2 was used, static
An electrostatic latent image developer was manufactured, and each evaluation was performed. Result is
The results are shown in Table 1 below.

[0118]

[Table 1]

Example 6 <Production of Toner Particles (Magenta)> In <Production Example of Flushing Cyan Pigment> in Example 1, the cyan pigment was replaced with a magenta pigment (CI Pigment Red 57: 1). Except for this, a flushing magenta pigment was obtained in the same manner as in Example 1. Further, in Example 1, <Production of toner particles (cyan)>, the flushing magenta pigment was replaced with the flushing magenta pigment. In the same manner as in Example 1, toner particles (magenta) were obtained.

<Production of Toner Particles (Yellow)> The procedure of Example 1 was repeated except that the cyan pigment was replaced with a yellow pigment (CI Pigment Yellow 180) in <Example of Production of Flushing Cyan Pigment>. In the same manner as in Example 1, except that the flushing yellow pigment was replaced with the above-mentioned flushing yellow pigment in <Production of Toner Particles (Cyan)> in Example 1, (Yellow).

<Production of Toner Particles (Black)> Using 96.0 parts by weight of the resin C obtained in Example 1 and 4 parts by weight of carbon black (primary particle diameter: 40 nm, # 25B manufactured by Mitsubishi Chemical Corporation), Premixing was performed, and the subsequent operation was performed in the same manner as in <Production of toner particles (cyan)> in Example 1 to obtain toner particles (black).

<Manufacture of each electrostatic latent image developer> Example 1 was repeated except that the toner particles used in "Production of toner" in Example 1 were changed to the above-described magenta, yellow and black toner particles. Toner 2 (magenta), toner 3 (yellow) and toner 4 (black) were obtained in the same manner as in "Production of Toner". The toner 2, toner 3 and toner 4: 6 parts obtained as described above and the carrier-1 manufactured in Example 1 were mixed with each other in a V-type blender in a V-type blender, and mixed with magenta, yellow and black. Were prepared.

<Evaluation of Image> Using each of the four colors of the above-described magenta, yellow, and black electrostatic latent image developers and the electrostatic latent image developer of Example 1 (cyan) was used. ,
A four-color full color copy test was performed. The copy test was performed in an environment of a temperature of 25 ° C. and a humidity of 60% using Acolor 935 as an image forming apparatus. As a result, good solid images and photographic images were obtained, and even in a copy test of 50,000 sheets, a clear image with no sense of image fogging or blurring and having a transparent feeling could be output.

[0124]

According to the electrostatic charge developer of the present invention, the fluidity of the toner powder is improved, and the appropriate chargeability and
The charging environment stability can be improved, a detailed image reproduction image can be formed stably, and a stable image can be provided for a long period of time. Further, according to the image forming method of the present invention using the electrostatic developer of the present invention,
A full-color image excellent in reproducibility of a solid image can be formed.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kazuhiko Yanagita 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Kanaishi 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. Reference) 2H005 AA08 AA21 BA06 BA07 CA02 CA21 CB07 CB10 CB13 DA05 EA01 EA07 FA02

Claims (2)

[Claims] 1. An electrostatic latent image developer comprising a toner and a carrier, wherein the toner comprises a toner particle containing a binder resin and a colorant, and at least two kinds of titanium compound fine particles and silica fine particles. And a mixing ratio (B / A) of the titanium compound fine particles (A) and the silica fine particles (B) in the external additive is in the range of 1 or more and 3 or less. The dynamic electric resistance under an electric field of × 10 ⁺⁴ V / cm is 10 to 1 × 10 ^{+8 in} the state of a magnetic brush.
An electrostatic latent image developer having a range of Ωcm. 2. A latent image forming step of forming an electrostatic latent image on a latent image carrier, and a developing step of forming a developer layer on a surface of the developer carrier disposed opposite the latent image carrier. Agent layer forming step, a developing step of developing the electrostatic latent image on the latent image carrier with the developer layer into a toner image, and a transfer step of transferring the developed toner image onto a transfer material, On the transfer material, four of cyan, magenta, yellow and black
In the image forming method for forming a full-color image by laminating color toner images, at least one of the four colors may be used.
An image forming method, wherein a color toner image is formed with the electrostatic latent image developer according to claim 1.