JP2769854B2 - Magenta developer for full color electrophotography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magenta developer for full-color electrophotography, comprising a carrier, a fixing resin, and a colorant, used for color electrophotography.

[Related Art] The required quality required of a colorant for a color electrophotographic magenta toner is as follows: 1) excellent spectral reflection characteristics (color characteristics), that is, having a clear magenta color; 2) good dispersibility in a resin. 3) Excellent stability to light, that is, good light fastness of the copy, 4) Uniform chargeability, 5) For the functions required of the copying machine Matching does not cause significant side effects, such as adhesion to the surface of the fixing roller and dyeability.

Conventional magenta colorants for color electrophotography include quinacridone pigments, thioindigo pigments, xanthene dyes, anthraquinone dyes, and azo dyes.

For example, JP-B-49-46951 discloses a 2,9-dimethylquinacridone pigment, JP-A-55-26574 discloses a thioindigo pigment, and JP-A-59-57256 discloses a xanthene dye. There is a description about. In addition, Tokuno Sho 55
JP-A-42383 describes an anthraquinone dye. Furthermore, Japanese Patent Publication No. 53-47174 describes a magenta toner using a quinacridone-based or rhodamine-based colorant in combination with an appropriate binder resin. However, none of the coloring agents satisfy all of the characteristics 1) to 5), and all have the advantages and disadvantages. For this reason, it is very difficult to rely on a single dye or pigment as the magenta colorant, and it is practical to use two or more colorants in combination to compensate for the disadvantages of each colorant.

For example, JP-A-57-130044 and JP-A-57-1300
No. 46 describes a magenta toner using two kinds of oil-soluble dyes. This magenta toner has a vivid color tone and excellent chroma, but on the other hand, one of the dyes contains a component that contaminates the silicone rubber used in the heating roller fixing device, so it is gradually fixed by continuous copying. The silicone roller is dyed, and finally, a so-called offset phenomenon in which the toner is fused to the heating roller is caused. Also, the combination of these oil-soluble dyes is effective in reducing the toner charge rather than increasing it. Therefore, it is possible to sufficiently prevent charge-up under low temperature and low humidity, and it is possible to guarantee a preferable image density. However, conversely, the toner scatters due to insufficient charging under high temperature and high humidity, thereby contaminating the inside of the apparatus, and fogging due to the low-charged toner tends to cause image contamination.

Accordingly, the present applicants have disclosed a novel quinacridone pigment excellent in light resistance, in which a xanthene dye having a high chroma is used as a colorant in combination with a quinacridone pigment excellent in light resistance in Japanese Patent Publication No. 61-18234. Magenta toner proposed.

The quinacridone-based organic pigment is a high-grade pigment having a slightly reddish color and excellent in light resistance and charge stability, but does not have sufficient performance as a magenta color when added alone. That is, with respect to the hue, the reflection in the bluish portion is less than the ideal magenta color, and the hue is reddish. It also has disadvantages such as poor chroma and inadequate vividness with respect to sharpness. Therefore, when used alone, the quality of color reproducibility is insufficient. However, when it is used as a toner, it has preferable characteristics in that carrier contamination due to repeated copying is small.

On the other hand, the xanthene-based dye is a so-called rhodamine-based dye, which is a colorant that emits fluorescence and exhibits a clear bluish pink color. Although this dye cannot be used as a magenta color when used alone, it has features such as obtaining a clear color or having a large coloring power.

However, such a magenta toner also has some disadvantages due to the pigment-dye combination system.

First, since the affinity between the dye and the pigment used is poor, they mutually repel each other in the binder resin during the dispersion step, making it difficult to make the color tone uniform, requiring a great deal of dispersion time and labor. In addition, since the compatibility of each dye / pigment with the binder resin is not uniform, at the same dispersion time, the two do not reach the dispersion equilibrium at the same time. Alternatively, in a long time when the pigment is sufficiently dispersed, a state such as separation of the dye is likely to occur.

As the separation of the dye proceeds in the binder resin, the dye comes to exist near the surface that is more energetically stable than inside the resin. When such a dispersed state is used as a toner, a large amount of toner on the surface of the toner causes a lot of poorly charged or insufficiently charged toner due to a dye which is often present on the surface of the toner, causing fogging, particularly at a high temperature at which the charge tends to be low. Under high humidity, there are problems such as contamination due to scattering inside the apparatus and the image density of magenta alone being too high, resulting in an inconsistent color copy image having a strong magenta color due to lack of color balance.

Further, if the color image is sandwiched on a vinyl chloride mat used on a desk in a general office and left for a long period of time, the dye in the toner migrates to the PVC mat and the adverse effect of transfer dyeing is likely to occur.

On the other hand, poor dispersion of the pigment is a main cause of lowering the saturation and lightness of the magenta toner, and narrows the color reproduction range of a color copied image. At the same time, the transparency of the OHP image is hindered.

In recent years, there has been a strong demand for higher image quality of copying machine images. On the other hand, the toner particle size is reduced to achieve high image quality. However, even if the toner particle size is reduced, the surface area of the toner increases, so that the charge amount increases.
It becomes easy to be excessive.

Further, since the toner particle diameter is small, a small amount of toner covers the surface of the carrier particles. Therefore, if the toner density is not reduced, toner scattering will occur, and if the toner density is reduced, the image density will be reduced.

Further, when the particle diameter is small, the toner has many contact points with each other, so that the fluidity of the toner is deteriorated. As a result, problems arise in the stability of toner replenishment and the charging of the replenished toner.

To prevent excessive charging, addition of conductive powder, addition of a low-charging substance, addition of a reverse polarity substance, and the like have been performed, but each has its own drawbacks.

First, when the conductive powder is added, the charge amount under high humidity is remarkably reduced, which causes image density unevenness and fogging. Further, since the conductive powder is generally colored, it adversely affects the color of the color toner.

In addition, addition of a low-charging substance (for example, JP-A-56-92545, JP-A-60-217368) requires a large amount of addition in order to obtain a sufficient flowability imparting effect. ,
In many cases, the charge amount is excessively lowered or a sufficient fluidity-imparting effect cannot be obtained.

In addition, when the opposite polarity substance is added, if coarse particles are contained in the opposite polarity substance, the toner aggregates around the center, and a toner mass of the opposite polarity may be generated. This toner mass is
It is developed in the non-image area, and deteriorates the image quality. Therefore, a step of removing coarse particles or toner lumps is required.

In addition, iron carriers and ferrite carriers are generally put into practical use. Here, when compared with black-and-white copying, full-color copying requires much better continuous gradation, but conventional carriers cannot fully satisfy this requirement even after copying many sheets. Was.

[Problem to be Solved by the Invention] However, an object of the present invention is to provide a magenta developer which has solved the above-mentioned problems.

That is, an object of the present invention is to provide a magenta developer that can obtain a clear color, has a large coloring power, and is excellent in light resistance.

Still another object is to provide a magenta developer which does not deteriorate the dyeing of a silicone rubber roller or the like during fixing.

Another object of the present invention is to provide a magenta developer which has excellent charging characteristics with excellent environmental stability, that is, maintains good developability even under low temperature and low humidity, and has appropriate development characteristics even under high temperature and high humidity. Things.

Another object is to provide a magenta developer which is less likely to be spent on a carrier even by repeated copying.

Another object is to provide a magenta developer having good dispersibility in a pigment-dye combination system.

Yet another object is to provide a magenta developer which does not stain vinyl chloride.

Another object is to provide a magenta developer having good compatibility with a binder resin.

Another object is to provide a magenta developer having excellent color reproducibility in full-color copying.

[Means and Actions for Solving the Problems] That is, the present invention relates to a magenta developer for full-color electrophotography, comprising a mixture of carrier particles and magenta toner in which magenta toner particles and a fluidity-imparting agent are mixed. The carrier particles have an average particle size of 20 to 60 μm, and the magenta toner particles have at least a styrene resin,
It contains a phenolic resin, a quinacridone pigment and a xanthene dye, has a volume average particle diameter of 6 to 10 μm, and has a specific surface area of 30 to 2 as measured by a BET method as the fluidity-imparting agent.
Alumina and / or titanium oxide in the range of 00 m ² / g and BE
The present invention relates to a magenta developer for full-color electrophotography, which is used in combination with a hydrophobic silica having a specific surface area of 80 m ² / g or more by a T method.

The particle diameter of the magenta toner particles used in the present invention is such that the volume average particle diameter is 6 to 10 μm, the coarse powder of 12.7 μm or more has a volume average distribution of 3.5% or less, and the fine powder of 5.04 μm or less has a number average distribution. Should be 35% or less, more preferably 30% or less. Since the particle size is small, toner adherence to a minute electrostatic latent image is faithful, and disturbance of toner adherence at the end of the electrostatic latent image is small. As a result, an image with high resolution and good color reproducibility can be obtained. In particular, since a latent image is minute in a halftone area in a digital copying machine,
The effect of the particle size is large and a good image is obtained.

In the production process for obtaining the toner of the present invention, as a method of dispersing the colorant in the resin, four kinds of styrene resin, phenol resin, quinacridone-based pigment, and xanthene-based dye are appropriately weighed, and simultaneously, using a Henschel mixer or the like. After the premix, the mixture may be subjected to kneading, or the colorant may be pre-treated with a phenol resin, and then a step of premix-kneading may be used. In a particularly preferred embodiment of the present invention, the xanthene dye is treated with a phenol resin and used as a finely treated dye.

The reason why such a treated dye greatly contributes to the improvement of the dispersibility of the colorant and the charging stability is not clearly understood, but the present inventors speculate as follows. In other words, this treated dye is a phenol resin containing a xanthene dye in the resin and dispersing the same. When these are dispersed in the toner, they are dissolved and dispersed in the toner as a single xanthene dye. It is considered that the dyed and dispersed phenol resin does not exist in the toner but is dispersed in the toner. In this case, the xanthene-based dye is held in a state of being wrapped in the phenol resin, and hardly migrates toward the styrene resin as the binder resin to cause adverse effects. In comparison, the contamination of the roller on the fixing silicon is significantly reduced, and the PVC contamination resistance is also improved. As described above, in order to take a state in which the treated dye is uniformly dispersed in the binder resin, when present on the toner surface, the xanthene-based dye, which causes a decrease in the chargeability of the toner, is dispersed by the untreated dye. Would be significantly reduced. Therefore, it is presumed that the chargeability of the toner was kept high even at high temperature and high humidity, and that scattering and fogging were less likely to occur. In addition, the uniform dispersion of the colorant means that the quality of the dispersion of the colorant greatly affects the image quality, such as chargeability, hue, and saturation, particularly as the particle size of the toner decreases. Considering
It can be seen that the performance is remarkably improved in terms of electrophotographic characteristics and color reproducibility. Although the toner of the present invention is more favorable in terms of environmental stability than the conventional magenta toner using a dye-based colorant, it tends to be excessively charged due to the reduced toner particle size. This tendency is notable, especially under low temperature and low humidity, and the density is easily reduced and fogging is likely to occur. Then, the present inventors were able to further improve environmental stability by adding alumina or titanium oxide having a low-charged substance.

These are 30 m ² / g (about 40 m ² / g) for the reasons described below.
mμ) to 200 m ² / g (about 12 mμ),
More preferably, 80 m ² / g (about 25 mμ) to 150 m ² / g (about 15 m
μ).

For example, in the case of alumina or titanium oxide having a BET specific surface area of more than 200 m ² / g, the fluidity is sufficient but the toner is liable to be deteriorated. Deterioration appears as a phenomenon in which the amount of charge changes significantly or the fluidity of the developer deteriorates when copying continues with little toner consumption.

Further, with alumina or titanium oxide having a BET specific surface area of less than 30 m ² / g, it becomes difficult to obtain sufficient fluidity even when used in combination with another fluidity-imparting agent. Further, the dispersion of the fluidity-imparting agent tends to be insufficient, and the image tends to fog.

Further, even in the range of 30 to ²⁰⁰ m ² / g, adverse effects occur unless used in combination with hydrophobic silica. In the range of 30 to 100 m ² / g, the use of only alumina or titanium oxide results in insufficient fluidity, so that it is necessary to use it together with hydrophobic silica having a high fluidity-imparting effect. In addition, in the range of 100-200 m ² / g,
Since the toner surface can be uniformly covered, the use of only low-charged alumina or titanium oxide results in a too low charge amount. Therefore, it is necessary to use in combination with negatively charged hydrophobic silica.

As described above, in terms of negative chargeability and fluidity-imparting ability, hydrophobic silica functions to supplement alumina and titanium oxide. Therefore, if the BET specific surface area is not less than 80 m ² / g, sufficient function cannot be obtained. More preferably, it is 150 m ² / g or more.

By using alumina, titanium oxide and hydrophobic silica together as in the configuration of the present invention, not only the above-described control of the charge amount but also other adverse effects associated with the reduction in the particle size of the toner are improved.

When the particle size of the toner is reduced, the Coulomb force and Van der Waals force acting on the toner become relatively stronger than the gravity and the inertial force, so that the adhesion force between the toners becomes stronger and toner aggregates are easily generated. Become. On the other hand, alumina and titanium oxide weaken the adhesive force due to charging and make it difficult to form toner aggregates. Also, when the particle size of the toner is reduced, the number of contact points between the toner and the carrier increases, and carrier spent tends to occur. On the other hand, alumina and titanium oxide also serve as good spacers between the carrier and the toner and exert a good effect.

Further, when alumina, titanium oxide and hydrophobic silica are used in combination, the fluidity of the toner becomes better than when each is used alone, and the mixing property of the developer and the toner cleaning property become better.

By using the above toner, hue, light fastness and roller dyeability are sufficiently satisfied, and a clear magenta color is obtained. It is also excellent in environmental stability. However, when the charge of the developer tends to leak, such as when the copier has not been operated for a long time under high temperature and high humidity, the developer using the conventional carrier has a slow rise in toner charge. The image quality was degraded due to scattering and fogging. Then, in the present invention, this problem was solved by using the following carriers. That is, the carrier used in the present invention is characterized by having a smaller average particle size and a sharper particle size distribution than conventional general carriers. Due to the small particle size, the number of times of contact between the carrier and the toner increases, the rise of the toner charge becomes faster, and even if the replenishment amount increases, the uncharged toner will not be developed. Furthermore, the rise of the charging speed is faster, so that the scattering due to the uncharged toner under high humidity,
An increase in fog can be prevented. Therefore, in combination with the above-described magenta toner, magenta development that is extremely vivid magenta, has excellent light fastness, and is resistant to splattering and fogging even when performing continuous copying of a color original having a large image area. Agent is obtained.

Also, by sharpening the particle size distribution, it solves the phenomenon that the fine powder carrier adheres to the photoreceptor along with the toner during development, which occurs gently with the small particle size carrier, and the poor charging due to the coarse powder carrier To prevent the image quality from deteriorating.

The ultrafine powder of 400 mesh pass is 20% by weight or less, preferably 16% by weight or less. If the amount exceeds 20% by weight, the carrier adheres to the photoreceptor, and smooth frictional charging with the toner is hindered to promote the edge effect. The fineness of the 350 mesh pass is 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less. If it exceeds 30% by weight, the rise of the toner charge becomes extremely poor, and the edge effect also increases.

Further, the amount of coarse powder of 250 mesh on is closely correlated with the sharpness of the image. If it exceeds 10% by weight, the scattering of the toner to the non-image portion increases, and the resolution of the image decreases and the roughness becomes rough. It is easy to occur. So 250 mesh on is 10
% By weight, preferably 7% by weight or less, more preferably 5% by weight or less.

The average particle size of the carrier is preferably from 20 to 60 μm, and more preferably from 30 to 56 μm. When the average particle diameter is less than 20 μm, the image density decreases due to the charge-up of the toner and the carrier adheres to the photoreceptor, and when the average particle diameter exceeds 60 μm, the fine line reproducibility of color copying deteriorates.

The magnetic properties of the carrier greatly affect the developing properties and transport of the developer. Particularly in color copying, importance is placed on the uniformity and gradation of the image as described above.

If the saturation magnetization exceeds 75 emu / g (for an applied magnetic field of 3000 Oersted), during development, a brush-like brush composed of carrier and toner on the developing sleeve facing the electrostatic latent image on the photoreceptor The ears are firmly tightened, and the gradation and the reproduction of halftone are deteriorated. On the other hand, when it is less than 55 emu / g, it is difficult to hold the toner and the carrier on the developing sleeve, and there is a disadvantage that fog and toner scattering are deteriorated. Further, when the residual magnetization and the coercive force of the carrier are too high, the transport of the developer in the developing machine is deteriorated, and image blurring and uneven density in a solid image are liable to occur. Therefore, the residual magnetization and the coercive force were each set to 10 emu /
g or less, 10 e or less (for an applied magnetic field of 3,000 Oe), preferably 5 emu / g or less and 6.0 e or less.

The developer used in the present invention is composed of carrier particles and particles containing a fluidity-imparting agent. Each material will be described below.

(1) Toner Particles The toner of the present invention uses a quinacridone-based pigment and a xanthene-based dye treated with a phenol resin as a colorant. It is 18 parts by weight, preferably 2 to 15 parts by weight. Also, quinacridone pigment / xanthene dye = 10
0/1 to 100/40, preferably 100/3 to 100/20.
Representative examples of quinacridone pigments include: and so on. Among them, CI Pigment Red 122 is particularly suitable as a colorant for magenta.

 Further, as a representative example of the xanthene-based colorant, C.I.Basic Violet 10 C.I.Basic Violet 11: 1 C.I.Solvent Red 49 can be mentioned.

These all have a clear blueish pink color. Since CIBasic Violet 10 and CIBasic Violet 11: 1 are basic dyes, they have some hygroscopicity, and in consideration of compatibility with resins, in the present invention, they are oil-soluble and not compatible with resins. Excellent CISolv with great coloring power
ent Red 49 is particularly suitable.

As a method for obtaining a treated dye, a xanthene dye and a phenol resin can be obtained by melt-kneading with a two-roll mill, a Banbury mixer, a kneader, a three-roll mill, or the like, and finely pulverizing to 10 μm or less. Alternatively, it can be obtained by mixing and dispersing in a solvent in which a phenol resin and a xanthene dye can be dissolved, removing the solvent, drying, and then performing a fine pulverization step. In this case, the polyester resin of the present invention may be kneaded or dissolved at the same time to disperse the three components in a uniform state, to obtain a pre-dispersed toner composition in advance, and then add a quinacridone pigment to obtain a magenta toner.

When the magenta toner of the present invention is used in a full-color copying machine, the fixing characteristics of the toner are extremely important. The fixed color toner is required to suppress irregular reflection by toner particles as much as possible and to have appropriate gloss and gloss.

Further, from the viewpoint of color reproduction, each toner layer must have transparency in order to be reproduced by overlapping another color toner on a certain color toner layer.
As a resin for a toner that can satisfy these requirements, a resin that exhibits solubility in a fairly narrow temperature range has been used. At the time of fixation, these color toners change their toner shape to a state close to complete melting, and have obtained glossiness and color reproducibility. These effects mean that the viscosity term is more important than the elastic term in the viscoelastic properties of the binder resin as the fixing property of the toner. That is, at the time of heating, the toner behaves as a viscous material, the heat melting property increases, and the gloss is obtained. However, such a binder resin design emphasizing the viscosity term inevitably lowers the intermolecular cohesion at the time of heat melting, and also increases the adhesion of the toner to the hot roll when passing through the fixing device. Become. These cause the hot offset phenomenon. In particular, when a silicone rubber roller is used as a fixing roller, a high-temperature offset is likely to occur due to a substantial reduction in the releasability of the silicone rubber surface due to repeated use regardless of whether the oil for releasing is applied. However, in the present invention, by using a styrene resin and a phenol resin having offset resistance in combination, it is possible to satisfy both color reproducibility and offset resistance, which are preferable for color copying.

Styrene resins and phenolic resins contain many polar groups, especially carboxyl groups, carbonyl groups,
Because it has alcoholic hydroxyl groups, phenolic hydroxyl groups, etc., the polymer blend system where both coexist is
The polar groups preferably influence each other, and good compatibility is obtained. The styrene resin in the present invention is,
In particular, it refers to a copolymer of a styrene derivative and an acrylic acid ester and a copolymer of a styrene derivative and an α-methylene aliphatic monocarboxylic acid ester.

Examples of the styrene derivative include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4
-Dimethylstyrene, pn-butylstyrene, p-te
rt-butylstyrene, pn-hexylstyrene, p-
n-octylstyrene, pn-nonylstyrene, p-
n-decylstyrene, pn-dodecylstyrene, p-
Examples include methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, p-nitrostyrene, and the like.

Examples of the acrylates include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. Examples include stearyl, 2-chloroethyl acrylate, and phenyl acrylate.

Further, as α-methylene aliphatic monocarboxylic acid esters, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid -2-ethylhexyl, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like.

The styrene resin of the present invention is produced by reacting the above radical polymerizable monomer with a radical polymerizable initiator to cross-link unsaturated portions in the monomer.

As the radical polymerization initiator, potassium peroxosulfate, peroxosulfates such as ammonium peroxosulfate, 2,3-azobisisobutyronitrile, azobis-2,4
-An azo compound such as dimethylvaleronitrile can be used.

The glass transition temperature of the obtained styrene resin is 50 ° C.
To 70 ° C, more preferably 55 ° C to 65 ° C.

As the phenolic resin used in the present invention, all those obtained by combining known monomers such as the following phenols and aldehydes as monomer constitutions can be used. Phenols include phenol, cresol, xylenol,
Alkyl phenols, paraphenyl phenols, bisphenol A, etc., and aldehydes include formaldehyde, paraformaldehyde, hexamethylenetetramine, furfural and the like.

To stabilize the charge characteristics, a charge control agent may be added to the toner according to the present invention as needed. For example, in the case of a negative toner, an anthraquinone-based dye having a magenta color or an organic metal complex such as a metal chelate of an alkyl salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid) is used. No. In the case of a positive toner, a magenta basic dye or a lake pigment thereof can be used.

(2) Fluidity-imparting agent Two kinds of fluidity-improving agents used in the present invention are used in combination, and one of them uses alumina or titanium oxide having a surface area of 30 m ² / g or more as measured by the BET method. Another type uses a hydrophobic silica of 80 m ² / g or more as measured by the BET method.

Alumina and titanium oxide can be relatively easily obtained in a fine particle size by a gas phase method, but there are no particular restrictions on the production method. However, particles having a plate-like or needle-like shape are not preferred.

The surface hydrophobization treatment may or may not be performed. There is no particular restriction on the crystal structure.

Hydrophobic silica having a degree of hydrophobicity of a certain degree or more has a large fluidity-imparting effect and is good, but there is no particular limitation when used in the present invention.

The application amount of the fluidity improver is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the classified toner. If the amount is less than 0.01 part by weight, there is no effect in improving the fluidity. If the amount exceeds 10 parts by weight, fogging and bleeding of characters and scattering inside the machine are promoted. In particular, in the case of a color toner, when an OHP image is formed, the sharpness of color is lost.

(3) Carrier particles As the carrier used in the present invention, known materials can be used without impairing the gist of the present invention. For example, surface-oxidized or unoxidized iron, nickel, copper, zinc, cobalt, Metals such as manganese, chromium, rare earths, and alloys or oxides thereof, and ferrites are preferable. Ferrite selected from metals of zinc, copper, nickel, and cobalt can be preferably used. There is no particular restriction on the manufacturing method.

It is also possible to coat the surface of the carrier with a resin or the like. As the method, any conventionally known method such as a method of dissolving or suspending a coating material such as a resin in a solvent, coating and adhering to a carrier, and a method of simply mixing with a powder can be applied.

The substance fixed to the carrier surface varies depending on the toner material. Examples thereof include polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal complex of di-tert-butylsalicylic acid, and styrene resin. ,
Acrylic resin, polyamide, polyvinyl butyral,
It is appropriate to use nigrosine, amino acrylate resin, basic dyes and lakes thereof, fine silica powder, fine alumina powder or the like alone or in combination, but it is not necessarily limited thereto.

The amount of the compound to be treated may be appropriately determined so that the carrier satisfies the above conditions, but is generally desirably 0.1 to 30% by weight (preferably 0.5 to 20% by weight) based on the carrier of the present invention.

In the present invention, a particularly preferred embodiment is Cu-Zn-
A coated ferrite carrier which is a ternary ferrite of Fe and whose surface is coated with a resin such as a fluorine-based resin or a styrene-based resin alone or in combination of two or more can be preferably used. As a result of earnest studies by the present inventors, when a styrene resin was used, a coated ferrite carrier coated with 0.01 to 5% by weight, preferably 0.1 to 1% by weight based on the carrier was particularly good.

Examples of the styrene resin include the following copolymers. For example, styrene-2-ethylhexyl acrylate (20: 80-80: 20), styrene-2-ethylhexyl acrylate-methyl methacrylate (20-60: 5-30: 10)
~ 50).

The method for measuring the particle size distribution of the carrier in the present invention is as follows.

1. Measure about 100 g of the sample to the nearest 0.1 g.

2. Use standard sieves of 100 Mesh to 400 Mesh (hereinafter referred to as sieves), stack them in order of size 100, 145, 200, 250, 350, 400 from the top, place a saucer on the bottom, put the sample particles in the top sieve and cover. .

3. This is sifted by a vibrator at 285 ± 6 horizontal revolutions per minute and 150 ± 10 vibrations per minute for 15 minutes.

4. After sieving, measure the iron powder in each sieve and tray to the nearest 0.1 g.

5. Calculate to the second decimal place by weight percentage and round to the first decimal place according to JIS-Z8401.

However, the size of the sieve frame is 200 mm inside diameter above the sieve surface,
The depth from the top surface to the sieve surface is 45mm.

The sum of the weights of iron powder in each part shall not be less than 99% of the mass of the starting sample.

The average particle size is determined from the above measured particle size distribution according to the following equation.

The BHU-60 is used to measure the magnetic properties of carriers.
Type magnetization measurement device (manufactured by RIKEN) is used.

About 1.0 g of a measurement sample is weighed, packed in a cell having an inner diameter of 7 mmφ and a height of 10 mm, and set in the above-mentioned apparatus.

In the measurement, first, an applied magnetic field is gradually applied to change up to 3,000 Oe. Next, the applied magnetic field is reduced, and finally a hysteresis curve of the sample is obtained on the recording paper. From this, the saturation magnetization, residual magnetization, and coercive force are obtained.

[Examples] Hereinafter, the present invention will be described in detail with reference to Examples. The carriers prepared in Table 1 were used.

The above formulation was melt-kneaded with a roll mill, cooled and then finely pulverized and classified with a jet mill to obtain a classified product having an average particle size of 8.2 μm. 0.3 parts of fine alumina powder having a specific surface area of 100 m ² / g by the BET method and a specific surface area of 250 m ² /
g, and 0.5 part of silica fine powder hydrophobized with hexamethyldisilazane was combined and externally added to obtain a magenta toner. This toner was mixed with a carrier (Table 1) to obtain a developer having a toner concentration of 4.5%.

Using this developer, a copy test was performed using a full-color copying machine (CLC-1, trade name) manufactured by Canon Inc. equipped with a color electrophotographic apparatus and having the OPC photosensitive drum shown in FIG.

The color tone of the obtained copy is a vivid magenta color, and has a sufficient color saturation. Although 10,000 copies of magenta single color were continuously made with a copying machine, no dyeing was observed on the surface of the silicone rubber fixing roller. Further, in order to observe copy light resistance, a forced irradiation test was performed using a fade meter (trade name: Super Fade Meter; manufactured by Suga Test Instruments Co., Ltd.). It was found that there was no change at 40 hours, and that there was no problem with light resistance. Further, the same copy durability test was performed for 5,000 sheets at a high temperature and high humidity of 30 ° C. and 80%, but no scattering in the machine or deterioration of fog occurred. A similar copy durability test was performed under low temperature and low humidity of 15 ° C and 10%.
An image having a sufficient image density was obtained with 10,000 copies.

A silica and alumina externally added toner was prepared in the same manner as in Example 1 with the above formulation, and the toner concentration was adjusted by combining with a carrier.
Evaluated as 4.5% developer. When a copy durability test was performed on 10,000 sheets, image density, fog, and scattering were hardly observed under low temperature and low humidity (15 ° C, 10%) and high temperature and high humidity (30 ° C, 80%). In the color of the image, the hue was shifted to the red side, the saturation was inferior, the color tone was considerably dull, and a clear magenta color was not obtained.

Comparative Example 2 As a fluidity imparting agent, the specific surface area by the BET method was 100 m ² / g.
Except that only 0.7 parts of silica fine powder hydrophobized with dimethyldichlorosilane was used, the same procedure as in Example 1 was carried out. It became even more noticeable as the run progressed.

Comparative Example 3 As a fluidity imparting agent, the specific surface area by the BET method was 120 m ² / g
Except that only 0.6 part of the alumina fine powder was used, the same operation as in Example 1 was carried out. As a result, toner scattering during copying running was remarkable, and fogging occurred in the image. Thereafter, the toner density was reduced to 4%, and the same operation was carried out. However, toner scattering and fog were at unsatisfactory levels.

Comparative Example 4 As a fluidity imparting agent, the specific surface area by the BET method was 20 m ² / g
0.3 parts of alumina fine powder and specific surface area by BET method are 25
0 m ² / g, and the same procedure as in Example 1 was carried out except that 0.5 part of silica fine powder hydrophobized with hexamethyldisilazane was used, the mixing state with the carrier particles was poor. As a result, toner particles that were not sufficiently triboelectrically charged were generated, and fogging became noticeable in the image after about 500 copies had been run. After that, since the control of the toner concentration became unstable, the running test was stopped.

With the above formulation, a toner was prepared in the same manner as in Example 1, and a classified product having an average particle size of 7.8 μm was obtained. 0.3 parts of alumina fine powder with a specific surface area of 100 m ² / g by BET method and BET
0.5 parts of silica fine powder having a specific surface area of 300 m ² / g and subjected to hydrophobic treatment with hexamethylene disilazane were combined and externally added to obtain a magenta toner. This toner was mixed with a carrier to obtain a developer having a toner concentration of 4.5%. Example 1
A copy durability test was conducted in the same manner as described above, however, the obtained copied image was sufficiently satisfactory in color (hue and saturation), light resistance, and roller dyeability. A copy durability test was performed on 10,000 copies under high temperature and high humidity conditions of 30 ° C. and 80% and low temperature and low humidity conditions of 15 ° C. and 10%, respectively. Fog, scattering, and reduction in image density were hardly observed. .

Comparative Example 5 A developer was prepared and evaluated in the same manner as in Example 2 except that a carrier was used. Although there was no problem with color and light fastness, fogging and scattering inside the machine occurred at 2,000 sheets at 23 ° C and 60% room temperature and normal humidity.

In addition, the carrier was spent by the toner during the running, and the frictional charging ability was reduced. Further, a copy durability test was performed on 5,000 sheets at a high temperature and a high humidity of 30 ° C. and 80%.

[Effects of the Invention] As described above, by using the developer obtained by the present invention, even when a color original having a large image area is continuously copied, scattering and fogging do not occur and there is no environmental change. A good image was obtained, light resistance was improved, and a very clear magenta color could be obtained, indicating that the present invention is industrially very useful.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a color electrophotographic copying machine applied to the color toner of the present invention. DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Rotary developing device 3 ... Supply hopper 4, ... Supply cable 5 ... Transfer drum, 6 ... Cleaner 7 ... Fixing device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-9466 (JP, A) JP-A-62-15557 (JP, A) JP-A-58-1157 (JP, A) JP-A-63-9 301960 (JP, A) JP-A-62-297857 (JP, A) JP-A-61-148457 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/087 G03G 9 / 09 G03G 9/10 G03G 9/08

Claims (2)

(57) [Claims] 1. A full-color electrophotographic magenta developer comprising a mixture of carrier particles, magenta toner particles and a magenta toner in which a fluidity-imparting agent is mixed, wherein the carrier particles have an average particle size of 20 to The magenta toner particles contain at least a styrene resin, a phenol resin, a quinacridone pigment and a xanthene dye, and have a volume average particle diameter of 6 to 10 μm. Specific surface area by method is 30 ~ 200
alumina and / or titanium oxide in the range of m ² / g and BET
A magenta developer for full-color electrophotography, which is used in combination with a hydrophobic silica having a specific surface area of 80 m ² / g or more according to a method. 2. The method according to claim 1, wherein said carrier particles have a fine powder content of not more than 30% by weight in a 350 mesh pass and an ultra fine powder content of 2 in a 400 mesh pass.
0 wt% or less, 250 mesh-on coarse powder amount is 10 wt% or less, saturation magnetization to applied magnetic field of 3,000 Oe is 55 to 75 emu / g, residual magnetization is 10 emu / g or less, coercive force is 2. The magenta developer for full-color electrophotography according to claim 1, wherein the developer is 10 e or less.