JP2000081722A - Electrostatic latent image developing toner, electrostatic latent image developer and full-color image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrostatic latent image developing toner giving good thin line reproducibility, good gradation and good graininess of a highlight part, capable of attaining image quality comparable to or higher than that by offset printing, excellent also in cleanability and suitable particularly for developing a digital latent image, to obtain an electrostatic latent image developer and to provide a full-color image forming method using the developer. SOLUTION: The electrostatic latent image developing toner comprises colored particles contg. at least a bonding resin and a colorant. The volume average particle diameter of the colored particles is 2.0-5.0 μ, colored particles of <=1.0 μm account for <=20% by number and colored particles of >5.0 μm account for <=10% by number. The colorant is pigment particles. The toner is preferably used as the toner of a two-component electrostatic latent image developer.

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 developing toner, an electrostatic latent image developer, and a full-color image forming method used in electrophotography, electrostatic recording, electrostatic printing, and the like. The present invention relates to an electrostatic latent image developing toner for developing a digital electrostatic latent image, an electrostatic latent image developer, and a full-color image forming method using the same.

[0002]

2. Description of the Related Art In electrophotography, a toner in a developer is adhered to an electrostatic latent image formed on a photoreceptor, transferred onto paper or a plastic film as a transfer material, and then fixed by heating or the like. Form an image. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer such as a magnetic toner. It is widely used at present because it has features such as good controllability and the like in sharing functions.

On the other hand, printers and copiers using electrophotography have been increasingly colorized in recent years, and electrostatic latent images have become finer due to improvements in the resolution of apparatuses. Along with this, the toner diameter has been reduced in recent years in order to faithfully develop the electrostatic latent image and obtain a higher quality image. In particular, a full-color copying machine that develops, transfers, and fixes a digital latent image with a chromatic toner achieves a certain high image quality by using a small particle size toner of 7 to 8 μm.

[0004] However, in order to realize the demand for higher resolution (improvement of fine line reproducibility, gradation improvement, etc.) in the future, it is necessary to further reduce the particle size of the toner and to have an appropriate particle size distribution. Further, the thickness of an image formed on a transfer material such as transfer paper (hereinafter simply referred to as “image thickness”) is at most a few μm in offset printing, but in the electrophotographic method, the particle size of the toner is Even in the case of a small particle size of about 7 to 8 μm, in the case of process black formed by full-color toner, at least three toner layers are overlapped, and it reaches about 10 μm to about 20 μm. An image with such a large image thickness gives a sense of strangeness visually, and in order to achieve high image quality comparable to offset printing, the difference in image structure from offset printing is improved, that is, It is necessary to reduce the image thickness. In order to reduce the image thickness, there is a method in which the pigment concentration in the toner is increased and the toner weight per unit area on the transfer material is reduced. Simply increasing the pigment concentration deteriorates the reproducibility of fine lines or dots, so that sufficient image quality cannot be obtained. Further, an image having a large amount of toner on the transfer material is easily damaged due to its large unevenness, and the formed image has low durability. From such a viewpoint, there is a strong demand for further reduction in the particle size of the toner.

[0005] In general, there are various technical obstacles to reducing the particle size of a toner as described below. Increased cost due to lower manufacturing efficiency (crushing efficiency) Poor powder fluidity Contamination of carrier and photoreceptor due to increase of powder adhesion, lowering of developability / transferability, and lowering of cleaning performance Charge controllability Fogging of non-image area due to reduction Environmental stability reduction Enlargement of color difference in charge amount There are various major issues to be solved as described above, and in fact, high image quality has not been realized by small particle size toner.

There are the following proposals for reducing the diameter of toner for forming a full-color image. 1) In Japanese Patent Application Laid-Open No. 5-107809, the weight average particle size of toner particles is 4 to 10 μm, the content of toner having a particle size of 4 μm or less is 15 to 60% by number, and the toner having a particle size of 4 to 8 μm. Content of 10 to 60% by number, 16 μm
There has been proposed a two-component developer including a toner containing a toner having a particle diameter of 2% by volume or less and a magnetic substance-dispersed carrier having a particle diameter of 10 to 60 μm. 2) JP-A-6-75430, JP-A-7-7782
In Japanese Patent Application Laid-Open No. 5-53, in order to obtain an image having high image density and excellent highlight reproduction and fine line reproduction, the toner particles have a weight average particle diameter of 3 to 7 μm and contain toner having a particle diameter of 5.04 μm or less. Amount of more than 40% by number, 4μ
20 to 70% by number of toner particles having a particle diameter of not more than 2 m, and 2 to 20% by volume of toner having a particle diameter of not less than 8 μm.
It has been proposed to use a toner containing 6% by volume or less of a toner having a particle diameter of not less than μm.

[0007] 3) JP-A-7-146589 discloses that
In order to obtain an image with high image density and excellent highlight reproduction and fine line reproduction, the weight average particle diameter of the toner particles is 3.5.
The toner having a particle diameter of 5.04 μm or less is contained in more than 35% by number, the toner having a particle diameter of 4 μm or less is contained in more than 15% by number, and the toner having a particle diameter of 8 μm or more is 2% or less. ２０20% by volume or less, 10.08 μm
It has been proposed to use a toner containing 6% by volume or less of the toner having the above particle diameter. 4) JP-A-10-48928 discloses that a toner having a volume average particle diameter of 4 to 10 μm, a content of toner having a particle diameter of 5 μm or less of 15 to 40% by number, and a particle diameter of 12.7 to 16 μm is used. A toner containing 0.1 to 5.0% by volume of a toner having a particle diameter exceeding 10 μm of 1.0% by volume or less and adding two types of external additives having different specific surface areas in a specific range is used. A proposal has been made.

[0008] The small particle size toners studied in the above-mentioned documents 1) to 4) have a weight average particle diameter or a volume average particle diameter of 3 to 10 μm, but a particle diameter of 5 μm or less. The ratio of the toner is not always large, and even if such a toner is used, there is a limit to the improvement of the image quality related to the reproducibility of fine lines and the gradation. In addition, 1
No consideration has been given to the relationship between the content of the toner having a particle diameter of not more than μm and various properties of the toner.

5) JP-A-8-227171 discloses that
In order to improve the transferability and cleaning properties, and to improve the deterioration of the toner characteristics due to the deterioration of the external additive, a 10-90 nm inorganic powder and a 30-120 nm hydrophobic powder are added to a toner having a weight average particle diameter of 1-9 μm with a defined shape factor. There is a proposal to add finely divided silicon compound powder.

[0010] However, in the toner studied in the document cited in 5), the idea regarding the particle size distribution of the toner particles is not specified, so that the toner having a particle size smaller than 5 μm in weight average particle size is used. However, improvement in image quality with a small particle size toner cannot be achieved. In fact, the weight average particle size of the toner particles described in the examples in this document is at least 6 μm.

On the other hand, in order to improve the texture of an image obtained by the dry electrophotography described above, a wet electrophotography has been put to practical use. In wet electrophotography, the average particle size is 1 to 2 μm.
m to obtain an image by developing with a liquid developer in which a toner of fine particles of about m is dispersed in a carrier liquid such as a high-boiling petroleum solvent, and according to the method, reproducibility of fine lines,
Disturbance of the image on the transfer material is improved, and the image thickness is reduced to improve the image quality.

[0012] However, the wet electrophotographic method has a drawback that the image quality is deteriorated because the toner image on the photoreceptor is disturbed by the carrier liquid when the image is formed on the photoreceptor. ing. Furthermore, it is necessary to install a recovery device for the generated organic solvent in order to prevent high-boiling petroleum-based organic solvents from being discharged outside the machine, making the device bulky and unsuitable for use in general offices and homes. Absent. Furthermore, it is not preferable from the viewpoint of environmental pollution. Therefore, development of a toner for developing an electrostatic latent image, which is a dry electrophotographic method and has high fine line reproducibility and high environmental stability, has been desired.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-quality image (particularly a full-color image) which has good fine line reproducibility, gradation (reproducibility) and highlight portion granularity. An electrostatic latent image developing toner excellent in cleaning properties, an electrostatic latent image developer, and a full-color image forming method using the same are provided. Particularly, an electrostatic latent image for developing a digital latent image is provided. An object of the present invention is to provide a developing toner, an electrostatic latent image developer, and a full-color image forming method.

Another object of the present invention is to provide a toner for developing an electrostatic latent image, an electrostatic latent image developer, and a full-color image capable of achieving image quality equivalent to or better than a full-color image formed by offset printing. It is to provide a forming method.

[0015]

Means for Solving the Problems The inventors of the present invention have developed colored particles required to achieve the above object (parts of the toner excluding external additives, ie, generally referred to as toner particles). Was examined for the particle size distribution. As a result, the volume average particle size of the colored particles is 2.0 to 5.0 μm,
Colored particles of 1.0 μm or less are 20% by number or less, 5.0 μm.
It has been found that setting the number of colored particles exceeding m to 10% by number or less is extremely effective in achieving improvement in fine line reproducibility, gradation and highlight portion granularity of an obtained image.

By controlling the volume average particle size of the colored particles to 5.0 μm or less, the reproducibility of fine lines, the gradation and the granularity of highlight areas are improved, and even if the pigment concentration in the colored particles is increased. To reduce the toner weight per unit area of the image formed on the transfer material by increasing the pigment concentration in the colored particles without reducing the fine line reproducibility, gradation, and highlight portion granularity. Since the thickness of the toner image formed on the transfer material can be suppressed to a small value, it is possible to obtain an image of high quality equal to or higher than that of offset printing without visually giving a sense of strangeness.

However, in order to achieve high image quality, it is not sufficient to simply specify the volume average particle size of the colored particles. That is, if there is a certain amount of small particles of colored particles,
This may cause poor cleaning. Conversely, if the colored particles having a large particle size are present in a certain amount or more, the reproducibility of fine lines becomes insufficient. In the present invention, the lower limit of the volume average particle diameter is set to 2.0 μm and 1.0 μm in order to solve the image quality problem such as fog and fine line reproducibility and the problem of poor cleaning.
The colored particles of m or less are suppressed to 20% by number or less, and the colored particles of more than 5.0 μm are suppressed to 10% by number or less.

Therefore, according to the present invention, it is possible to obtain a high-quality image which is excellent in fine line reproducibility and gradation and which does not give a sense of discomfort visually, comparable to or higher than offset printing. And good cleaning properties.

On the other hand, when an image is to be formed using the electrostatic latent image developing toner of the present invention (hereinafter sometimes simply referred to as “toner”), in order to obtain an image having the same texture as that of offset printing, The weight of the toner per unit area of the image formed on the transfer material can be reduced. Even if the weight of the toner per unit area of the image is reduced, a sufficient image density can be achieved, and in order to ensure the water resistance, light resistance, or solvent resistance of the image, as a colorant contained in the colored particles, It is essential to use pigment particles having high coloring power and excellent water resistance, light resistance, or solvent resistance.

In the present invention, the particle size distribution of the colored particles is more preferably from 1.0 to 2.5 μm.
５０50% by number.
m is 75% by number or more.
In the present invention, the average particle diameter of the dispersed particles of the pigment particles in the colored particles is preferably not more than 0.3 μm in circle equivalent diameter.

In the present invention, the pigment concentration of the pigment particles in the colored particles is C (% by weight), and the true specific gravity of the colored particles is a.
(G / cm ³ ), and the volume average particle diameter of the colored particles is D (μm).
In this case, it is preferable to satisfy the relationship of the following expression (1). 25 ≦ a · D · C ≦ 90 (1)

In particular, from the viewpoints of the difference in coloring properties and the molecular structure peculiar to the color of the pigment, the following formulas (1-1) are used for each color.
It is preferable to satisfy the relationship of (1-4). 25.ltoreq.a.D.C.ltoreq.60 for cyan pigment (1-1) 25.ltoreq.a.D.C.ltoreq.60 for magenta pigment (1-2) 30.ltoreq.a.multidot. D · C ≦ 90 (1-3) For black pigment, 25 ≦ a · D · C ≦ 60 (1-4)

The toner for developing an electrostatic latent image of the present invention is preferably used as a toner of a so-called two-component electrostatic latent image developer comprising at least a carrier and a toner.
At this time, the carrier preferably has a volume average particle size of 45 μm or less, and preferably has a resin coating layer on the surface.

At least a latent image forming step of forming an electrostatic latent image on the latent image carrier, and a toner for forming a toner layer on the surface of the developer carrier disposed opposite to the latent image carrier A method of forming an electrostatic latent image on a latent image carrier with the toner layer, a transfer step of transferring the developed toner image onto a transfer material, and an image forming method comprising: When the toner for developing an electrostatic latent image of the present invention is used, an image obtained on a transfer material has extremely high image quality.

In the full-color image forming method of forming a full-color image by laminating at least four-color toner images of cyan, magenta, yellow and black on a transfer material, the four-color toner used in the present invention is used. By using the toner for developing an electrostatic latent image described above, the reproducibility of fine lines and the disorder of the image on the transfer material are improved, the image thickness is reduced, and an extremely high-quality image can be formed.

At this time, in the toner image of each color to be formed,
And the weight of each toner is 1cm ^Two0.40m per
g, the thickness of the image on the transfer material
Image quality and extremely high image quality.
This is preferable. Especially for solid images with 100% image area ratio
1cm weight of each color toner^Two0.10 per
It is preferable to be 0.40 mg.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a toner for developing an electrostatic latent image comprising colored particles containing at least a binder resin and a coloring agent, wherein (a) the colored particles have a volume average particle diameter of 2.
0 to 5.0 μm, and colored particles of 1.0 μm or less
0% by number or less, and colored particles exceeding 5.0 μm are 1
0% by number or less, and (b) the toner for developing an electrostatic latent image, wherein the colorant is a pigment particle.

(A) Particle Size and Particle Size Distribution of Colored Particles As described above, the volume average particle size of the colored particles should be at least 5.0 in order to improve the reproducibility and gradation of fine lines.
It is essential that it is not more than μm. If it exceeds 5.0 μm, the ratio of coarse particles increases, and fine line reproducibility and gradation deteriorate. In the present invention, "reproducibility of fine lines"
It mainly means whether or not a fine line having a width of 30 to 60 μm, preferably 30 to 40 μm can be faithfully reproduced, and further, it is taken into consideration whether or not a dot having the same diameter can be reproduced.

On the other hand, the lower limit of the volume average particle size of the colored particles must be 2.0 μm or more. 2.
If the thickness is less than 0 μm, various problems associated with powder characteristics such as deterioration of powder fluidity, developability, or transferability of toner and deterioration of cleaning properties of toner remaining on the photoreceptor surface occur. May come.

In consideration of the above, the range of the volume average particle size of the colored particles is 2.0 to 5.0 μm, preferably 2.0 to 4.5 μm, more preferably 2.0 to 4.0 μm.
m, more preferably 2.0 to 3.5 μm.

In the present invention, the particle size distribution of the colored particles is further defined. Specifically, among all the colored particles, 1.0 μm
m is 20% by number or less, and 5.0 μm
It is essential that the particle size distribution is such that the number of colored particles exceeding 10% is 10% by number or less.

If the number of colored particles of 1.0 μm or less in all the colored particles exceeds 20% by number, the non-electrostatic adhesion of the colored particles becomes large, so that cleaning failure tends to occur. More preferably, the number of colored particles of 1.0 μm or less in all the colored particles is 10% by number or less. In addition, 1.0% of all the colored particles
By setting the number of colored particles having a size of μm or less within the above range, fog is also improved.

On the other hand, when the number of the colored particles exceeding 5.0 μm in all the colored particles exceeds 10% by number, it is impossible to achieve the improvement of the reproducibility of the fine line as the object of the present invention.
More preferably, the number of colored particles exceeding 5.0 μm in all the colored particles is 5% by number or less.

In the present invention, 5.0 μm is used as a parameter defining the large particle size side of the particle size distribution of the colored particles.
Although the number% of the colored particles exceeding m is used, the reference particle size can be defined by another numerical value. Specifically, 4.
When 0 μm is the standard particle size, 4.0% of all the colored particles are used.
It is preferable that the number of colored particles having a particle size of μm or less is 75% by number or more. In addition, in view of the volume average particle diameter and the particle size distribution of the colored particles in the present invention, when 75% by number or more of the colored particles of 4.0 μm or less in all the colored particles are 5.0 μm.
The number of colored particles exceeding m is generally 10% by number or less.

The particle size distribution of the colored particles in the toner for developing an electrostatic latent image according to the present invention is such that all the colored particles are reproduced in order to faithfully reproduce the minute dots required for reproducing the extremely highlighted portion of the obtained image. Medium, 5 to 1.0 to 2.5 μm colored particles
個数 50% by number, more preferably 1
0 to 45% by number. If the colored particles having a diameter of 1.0 to 2.5 μm exceed 50% by number, selective development in which the colored particles on the larger diameter side are selectively consumed is more likely to occur during development.
Colored particles having a relatively small diameter of 2.5 μm are not easily consumed, and disadvantages such as fogging and poor cleaning at the time of copying a large number of sheets are apt to occur. on the other hand,
If the number of colored particles having a size of 1.0 to 2.5 μm is less than 5% by number, the reproducibility of the fine dots tends to decrease, which is not preferable.

In order to obtain colored particles having such a particle size distribution, when obtaining by a pulverization method, conditions for pulverization and classification are as follows:
When it is obtained by a polymerization method, the polymerization conditions may be appropriately set. If the particle size is reduced as much as possible by a normal pulverization method, over-pulverization hardly occurs, a pulverized product having a particle size distribution close to the particle size distribution of the colored particles in the present invention is obtained, and it is necessary to adjust the particle size distribution using a classifier. There is almost no
Even if it is necessary to adjust the particle size distribution, the amount of the pulverized material to be removed is small and the pulverization method is preferable because the production cost can be kept low.

The particle size distribution of the colored particles can be measured by various methods. In the present invention, the measurement is performed using a Coulter Counter TA2 type (manufactured by Coulter Co., Ltd.) with an aperture diameter of 50 μm. Only when measuring the number distribution, the measurement was performed with the aperture diameter being 30 μm.

Specifically, a sodium chloride aqueous solution (10
g / liter) of a dispersion (surfactant: Triton X1)
00) Two to three drops and a measurement sample were added, and the mixture was subjected to a dispersion treatment for 1 minute by an ultrasonic disperser, and then the measurement was carried out using the above apparatus.

(B) Colored Particles In the present invention, the colored particles contain at least a binder resin and a colorant. The binder resin contained in the colored particles preferably has a glass transition point of 50 to 80C, more preferably 55 to 75C. When the glass transition point is lower than 50 ° C., the heat storage property is reduced, and when it is higher than 80 ° C., the low-temperature fixability is lowered, which is not preferable.

The softening point of the binder resin is 80 to 1
The temperature is preferably 50 ° C, more preferably 90 to 1 ° C.
The temperature is 50 ° C, more preferably 100 to 140 ° C. When the softening point is less than 80 ° C, the heat storage property is reduced, and the
If the ratio exceeds, the low-temperature fixability is lowered, so that each is not preferred. Further, the number average molecular weight of the binder resin is 100
0-50000, weight average molecular weight of 7000-5
A range of 00000 is preferred.

As the binder resin, those conventionally used as toner binder resins are used without any particular limitation. Styrene-based polymers, (meth) acrylate-based polymers, and styrene- (meth) acrylic As the acid ester polymer, one selected from the following styrene monomers, (meth) acrylate monomers, other acrylic or methacrylic monomers, vinyl ether monomers, vinyl ketone monomers, N-vinyl compound monomers, etc. Alternatively, a polymer obtained by polymerizing two or more monomers is suitably used.

Examples of the styrene monomer include styrene, o-methylstyrene, ethylstyrene, p-methoxystyrene, p-phenylstyrene, 2,4-dimethylstyrene, pn-octylstyrene, and pn-decylstyrene. And styrene derivatives such as pn-dodecylstyrene and butylstyrene.

The (meth) acrylate monomers include, for example, methyl (meth) acrylate and (meth) acrylate.
Ethyl acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, (meth) acrylic acid-2- (Meth) acrylates such as ethylhexyl, stearyl (meth) acrylate, phenyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate; and the like.

Other acrylic or methacrylic monomers include, for example, acrylonitrile, methacrylamide, glycidyl methacrylate, N-methylolacrylamide, N-methylolmethacrylamide,
-Hydroxyethyl acrylate and the like.

Examples of the vinyl ether monomer include vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether.

Examples of the vinyl ketone monomer include vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone.

Examples of the N-vinyl compound monomer include N-vinyl compounds such as N-vinylpyrrolidone, N-vinylcarbazole and N-vinylindole.

In the present invention, polyester is preferably used as a binder resin from the viewpoint of fixability. As such a polyester, those synthesized by polycondensation of a polyvalent carboxylic acid and a polyhydric alcohol can be used.

The polyhydric alcohol monomers include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, 1,5-pentanediol, 1,6- Aliphatic alcohols such as hexanediol and neopentyl glycol; alicyclic alcohols such as cyclohexanedimethanol and hydrogenated bisphenol; bisphenols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct.
Derivatives and polyvalent carboxylic acids such as phthalic acid, terephthalic acid, aromatic carboxylic acids such as phthalic anhydride and their acid anhydrides, succinic acid, adipic acid, sebacic acid, azelaic acid, saturated and unsaturated such as dodecenyl succinic acid Carboxylic acids and their anhydrides can be used.

Pigment particles are used as the coloring agent contained in the colored particles. In the present invention, even if the weight of the toner per unit area of the image is reduced, sufficient image density can be achieved, and in order to ensure water resistance, light resistance, or solvent resistance of the image, the toner is contained in the colored particles. As a coloring agent to be used, it is essential to use pigment particles having high coloring power and excellent water resistance, light resistance, or solvent resistance.

Examples of usable pigments include carbon black, nigrosine, graphite, C.I. I. Pigment Red 48: 1, 48: 2, 48: 3, 53: 1, 57: 1,
112, 122, 123, 5, 139, 144, 14
9, 166, 177, 178, 222, C.I. I. Pigment Met Yellow 12, 14, 17, 97, 180, 18
8, 93, 94, 138, 174, C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I.
I. Pigment Blue 15: 3, 15, 15: 2, 6
0, C.I. I. Pigment Green 7 and the like. Among them, carbon black, C.I. I. Pigment Red 48: 1, 48: 2, 48: 3, 53: 1, 5
7: 1, 112, 122, 123, C.I. I. Pigment Met Yellow 12, 14, 17, 97, 180, 188,
C. I. Pigment Blue 15: 3 is preferred. These pigments can be used alone or in combination of two or more.

In order to improve the coloring power and transparency of a color toner, the present inventors have already determined that the average particle size of dispersed fine particles in a binder resin of pigment fine particles, which is a colorant of a toner, by a melt flushing method is equivalent to a circle. A method has been proposed in which the diameter is reduced to 0.3 μm or less (Japanese Patent Application Laid-Open No. H4-242252).
This technique is extremely effective for the toner for developing an electrostatic latent image of the present invention, which requires a high colorant concentration in the colored particles. That is, the melt flushing method as a means of dispersing the pigment particles in the binder resin is a method of replacing the water in the pigment-containing cake in the pigment production step with a molten binder resin, and according to this method, The average particle size of the dispersed pigment particles in the binder resin can be easily reduced to 0.3 μm or less in circle equivalent diameter, and the transparency of the toner can be ensured, and good color reproduction can be achieved.

In the present invention, the circle-equivalent diameter of the average particle diameter of the pigment particles dispersed in the binder resin is defined as the diameter of a part of the colored particles which is taken out, embedded in the resin, and dispersed in the colored particles. A slice for observation was cut out so that the state could be observed, an enlarged photograph was taken at a magnification of 15,000 with a transmission electron microscope, the area of the pigment particles was measured with an image analyzer, and the diameter of a circle corresponding to the area was measured. Means the value calculated.

In the toner for developing an electrostatic latent image according to the present invention,
The colored particles have a volume average particle size of 5.0 μm or less, and it is necessary to increase the coloring power per colored particle. In particular,
In the case of a full-color image in which colored particles are superimposed on a transfer material to form a color, if the transparency of the colored particles is not good, when expressing secondary colors such as red and green and tertiary colors such as process black, coloring of the upper layer Although the color development of the lower layer may be alienated by the particles and good color reproduction may not be achieved, this problem is solved by setting the average particle size of the dispersed particles in the binder resin to 0.3 μm or less in circle equivalent diameter. It is possible to do.

As described above, the toner for developing an electrostatic latent image of the present invention has a small particle size, and it is difficult to obtain a sufficient image density with a pigment concentration similar to that of a conventional toner having a larger particle size. Even if the toner for developing an electrostatic latent image of the present invention has a small particle size, its volume average particle size ranges from 2.0 μm to 5.0 μm, and the unit area in a solid image is small. There is also a large difference in the toner weight per unit (TMA). Therefore, it is desirable to set the necessary pigment concentration according to TMA.

TMA is the volume average particle diameter D (μ
m) and the true specific gravity a, and the pigment concentration C (%) in the colored particles preferably satisfies the following relational expression (1). 25 ≦ a · D · C ≦ 90 (1)

If the value of aDC (hereinafter sometimes abbreviated as "aDC") is less than 25, the coloring power is not sufficient, and it is difficult to obtain a desired image density, and a desired image density is obtained. Therefore, if the amount of toner formed at the time of development is increased, the image gloss difference occurs despite the reduced diameter of the angled colored particles,
This is not preferable because the thickness of the image increases, the reproducibility of fine lines also decreases, and the transferability also decreases.

On the other hand, when the value of aDC exceeds 90, although sufficient image density can be obtained, background contamination is apt to occur due to scattering of toner to a small amount of non-image area. It is not preferable because problems such as an increase in viscosity and deterioration of fixability may occur.

Further, there is a difference in coloring power depending on the color, and it is more preferable that the following relational expressions (1-1) to (1-4) are satisfied for each color. Cyan: 25 ≦ a · D · C ≦ 90 (1-1) Magenta: 25 ≦ a · D · C ≦ 60 (1-2) Yellow: 30 ≦ a · D · C ≦ 90・ ・ (1-3) Black: 25 ≦ a ・ D ・ C ≦ 60 (1-4)

Of course, even for pigments of the same color, the coloring power varies depending on the chemical structural formula and the like, so that the pigment concentration is preferably set appropriately within the above range according to the type of pigment used. Good.

The colored particles can be produced by any conventionally known method such as a pulverization method or a polymerization method by suspension polymerization or emulsion polymerization. Here, the crushing method is
After preliminarily mixing a binder resin, a colorant, and other additives as necessary, the mixture is melt-kneaded in a kneader, cooled, pulverized and classified to make the particles have a specified particle size distribution.

[Other Additives] In the present invention, it is preferable to add an external additive for the purpose of controlling charging.
Materials of the inorganic fine powder that can be used as an external additive include silicon oxide, titanium oxide, tin oxide, zirconium oxide,
Examples include metal oxides such as tungsten oxide and iron oxide, nitrides such as titanium nitride, and titanium compounds. As the addition amount of the external additive, based on 100 parts by weight of the colored particles,
Preferably it is 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight.

As a method of adding the inorganic fine powder to the toner, for example, a conventionally known method of adding the inorganic fine powder and the colored particles to a Henschel mixer and mixing them can be adopted.

Further, in the present invention, in order to improve powder properties such as powder fluidity and powder adhesion, to prevent a decrease in transfer efficiency and chargeability, and to reduce environmental dependency, As an additive, at least 30 nm or more and 200 nm
It is preferable to use at least one kind of ultrafine particles having the following average primary particle diameter and at least one kind of ultrafine particles having an average primary particle diameter of 5 nm or more and less than 30 nm.

The ultrafine particles reduce the adhesion between the colored particles or between the colored particles and the photoreceptor or carrier,
It has a function of preventing a decrease in developability, transferability, or cleaning performance. The average primary particle size of the ultrafine particles is 30n
m to 200 nm, more preferably 35 nm to 1
50 nm or less, more preferably 35 nm or more and 100 n
m or less. If it exceeds 200 nm, the toner tends to be detached from the toner, and the effect of reducing the adhesive force cannot be exhibited. On the other hand, if it is less than 30 nm, it will act as ultra-fine particles described later.

The ultra-fine particles improve the fluidity of the toner (colored particles), reduce the degree of aggregation, and contribute to the improvement of environmental stability through effects such as suppression of thermal aggregation. The average primary particle diameter of the ultrafine particles is from 5 nm to less than 30 nm, more preferably from 5 nm to less than 29 nm, and still more preferably from 10 nm to 29 nm. When the thickness is less than 5 nm, the toner is easily buried in the surface of the colored particles due to stress applied to the toner. On the other hand, if it is 30 nm or more, it will function as the ultrafine particles described above. In addition, in this specification, a "primary particle diameter" means a primary particle diameter equivalent to a sphere.

Examples of the ultrafine particles include metal oxides such as hydrophobized silicon oxide, titanium oxide, tin oxide, zirconium oxide, tungsten oxide, and iron oxide; nitrides such as titanium nitride; and fine particles made of a titanium compound. Preferably, the fine particles are made of hydrophobized silicon oxide. The hydrophobization is performed by treating with a hydrophobizing agent. As the hydrophobizing agent, any of chlorosilane, alkoxysilane, silazane, and silylated isocyanate can be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, ter -Butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane and the like.

Examples of the ultrafine particles include fine particles made of a metal oxide such as a hydrophobic titanium compound, silicon oxide, titanium oxide, tin oxide, zirconium oxide, tungsten oxide and iron oxide, and a nitride such as titanium nitride. Among them, titanium compound fine particles are preferred.

The titanium compound fine particles are a reaction product of metatitanic acid and a silane compound which is highly hydrophobic, hardly generates aggregates because of no baking treatment, and has good dispersibility at the time of external addition. Preferably, there is. Also,
As the silane compound at that time, an alkylalkoxysilane compound and / or a fluoroalkylalkoxysilane compound that can control the charge of the toner well and can reduce the adhesion to the carrier and the photoreceptor are preferably used.

The metatitanic acid compound which is a reaction product of metatitanic acid with an alkylalkoxysilane compound and / or a fluoroalkylalkoxysilane compound is obtained by peptizing metatitanic acid synthesized by a sulfuric acid hydrolysis reaction, Those obtained by reacting metatitanic acid with an alkylalkoxysilane compound and / or a fluoroalkylalkoxysilane compound can be suitably used. Examples of the alkylalkoxysilane to be reacted with metatitanic acid include methyltrimethoxysilane,
Ethyltrimethoxysilane, propyltrimethoxysilane, isobutyltrimethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-
Octyltrimethoxysilane, n-decyltrimethoxysilane and the like. Examples of the fluoroalkylalkoxysilane compound include trifluoropropyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, and heptadecafluoro. Decylmethyldimethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, (heptadecafluoro-1,1,1,2) , 2-tetrahydrodecyl) triethoxysilane, 3- (heptafluoroisopropoxy) propyltriethoxysilane and the like can be used.

By using two types of external additives, ultrafine particles and ultrafine particles, the effects of the addition of both can be obtained.

However, if the total amount of the external additives is too large, free (not adhered to the colored particles) external additives are generated, and the photoreceptor and the carrier surface are easily contaminated with the external additives. . In addition, if both the ultrafine particles and the ultrafine particles do not have a certain amount of addition, the effect of adding both of them cannot be obtained. Further, if the amount of the ultrafine particles is too large, the effect of improving the powder fluidity cannot be obtained, and if the amount of the ultrafine particles is too large, the effect of improving the powder adhesion cannot be obtained. Therefore, it is necessary to appropriately control the amount of the external additive to be added.

The appearance of the effects of the addition of the external additive and the variation in the characteristics of the various powders do not depend on the absolute amount of the external additive to be added, but on the coverage of the surface of the colored particles. Things. Here, the coverage of the external additive with respect to the surface of the colored particles is defined as a coverage of 1 when the state where the external additive having the same diameter and the surface of the colored particles is closest packed in a single layer is an ideal state.
When it is assumed to be 00%, it means a percentage representing how much the actual external additive covers the actual surface of the colored particles. This can be expressed by the following equation (2).

F = √3 · D · ρ _t · (2π · d · ρ _a ) ⁻¹ · C × 100 (2) (in the above formula, F is the coverage (%), and D is the colored particles. , Ρ _t is the true specific gravity of the colored particles, d is the primary particle average particle size of the external additive (μm), ρ _a is the true specific gravity of the external additive,
And C are the weight of the external additive x (g) and the weight of the colored particles y
(G) and the ratio (x / y). )

In the present invention, the coverage of the external additive on the surface of the colored particles determined by the above formula (2) is at least 20% for both the ultrafine particles and the ultrafine particles Fb, Is preferably 100% or less. In addition, "the total of the coverage of all the external additives" refers to the total of the coverage of each external additive obtained by individually calculating the coverage of each external additive to be added.

If the covering rate Fa of the ultrafine particles is less than 20%, the effect of adding the ultrafine particles cannot be obtained. The coverage Fa of the ultrafine particles is preferably from 20 to 80%, more preferably from 30 to 60%.

If the ultra-fine particle coverage Fb is less than 20%, the effect of adding the ultra-fine particles cannot be obtained. The coverage Fb of the ultrafine particles is preferably 20 to 80%, more preferably 30 to 60%.

If the total coverage of all the external additives exceeds 100%, a large amount of free external additives is generated, and the photoreceptor and the carrier surface are easily contaminated with the external additives. The total of the coverage of all the external additives is preferably 40 to 100%, more preferably 50 to 90%.

The relationship between the ultrafine particle coverage Fa (%) and the ultrafine particle coverage Fb (%) more preferably satisfies the following expression (3). 0.5 ≦ Fb / Fa ≦ 4.0 (3) Outside this range, it is difficult to obtain the effect of adding ultrafine particles or ultrafine particles, which is not preferable. Also,
In order to optimize the effect of adding ultrafine particles or ultrafine particles, it is more preferable to satisfy the following expression (3 ′). 0.5 ≦ Fb / Fa ≦ 2.5 (3 ′)

As a method for adding the ultrafine particles and the ultrafine particles to the toner, for example, a conventionally known method of adding the ultrafine particles, the ultrafine particles and the colored particles to a Henschel mixer and mixing them can be adopted.

The toner for developing an electrostatic latent image according to the present invention may contain a charge controlling agent, a release agent, and the like, if necessary, as long as color reproducibility and transparency are not affected. Examples of the charge control agent include chromium azo dyes, iron azo dyes, aluminum azo dyes, salicylic acid metal complexes, and organic boron compounds. Examples of the release agent include polyolefins such as low-molecular-weight propylene and low-molecular-weight polyethylene, and natural waxes such as paraffin wax, candelilla wax, carnauba wax, and montan wax, and derivatives thereof.

[Electrostatic Latent Image Developer] The electrostatic latent image developing toner of the present invention is mixed with a carrier and used as a two-component electrostatic latent image developer.

The carrier preferably used together with the toner for developing an electrostatic latent image of the present invention is not particularly limited, and magnetic particles such as iron powder, ferrite, iron oxide powder, nickel, etc. As a resin-coated carrier particle obtained by coating the surface with a known resin such as a styrene-based resin, a vinyl-based resin, an ethyl-based resin, a rosin-based resin, a polyester-based resin, and a methyl-based resin to form a resin coating layer. Alternatively, magnetic material-dispersed carrier particles obtained by dispersing magnetic material fine particles in a binder resin can be used.

Among them, a coated resin type carrier having a resin coating layer is particularly preferable because the chargeability of the toner and the resistance of the entire carrier can be controlled by the configuration of the resin coating layer. As the material of the resin coating layer, any resin conventionally used in the art as a material of the resin coating layer of the carrier can be selected. In addition, the type of the resin may be single or two or more.

The carrier preferably has a volume average particle diameter of 45 μm or less, more preferably 10 to 40 μm, and still more preferably 15 to 35 μm.
It is. By improving the volume average particle diameter of the carrier to 45 μm or less, it is possible to improve background contamination and density unevenness caused by charge rising, deterioration of charge distribution, and decrease in charge amount due to the reduction in particle diameter of the toner (colored particles). Can be.

The mixing ratio of the toner for developing an electrostatic latent image to the carrier is preferably in the range of 1: 100 to 20: 100 by weight, more preferably 2: 100 to 15: 100.
And more preferably in the range of 3: 100 to 10: 100.

[Image Forming Method] The toner for developing an electrostatic latent image of the present invention is disposed at least in a latent image forming step of forming an electrostatic latent image on the latent image carrier, and opposed to the latent image carrier. Forming a toner layer on the surface of the developer carrier, developing the electrostatic latent image on the latent image carrier with the toner layer, and transferring the developed toner image onto a transfer material. And a transfer step of transferring the toner to a toner image.

By using the toner for developing an electrostatic latent image of the present invention, the obtained image has good fine line reproducibility and good gradation and no fog. Since the fine line reproducibility is good, it is very suitable especially for developing a digital latent image.

Further, at least cyan,
In an image forming method for forming a full-color image by laminating toner images of three colors of magenta and yellow or further four colors of black, the toner for developing an electrostatic latent image of the present invention is used as the toner of these three or four colors. , The resulting image has good fine line reproducibility and gradation and no fog, and the small particle size of the toner results in fine line reproducibility, gradation and highlight portion granularity. It is good, and even if the pigment concentration in the colored particles is increased, the fine line reproducibility, gradation, and the granularity of the highlight portion do not decrease. The toner weight per unit area of the image formed on the transfer material can be reduced, and the thickness of the toner image formed on the transfer material can be suppressed to be small, so that it does not give a sense of strangeness visually, Offset printing comparable, or to achieve a more high quality. Further, since the thickness of the toner image on the transfer material is small, the unevenness is small and the toner image is not easily damaged by external force, and thus the formed image has high durability.

At this time, it is preferable that the toner weight per 1 cm ² (TMA) of each color toner image to be formed is 0.40 mg or less.
It is more preferably at most 0.35 mg, even more preferably at most 0.30 mg. By keeping the TMA low as described above, the thickness of the toner image on the transfer material can be reduced, and high image quality comparable to offset printing without any visual discomfort can be achieved. Further, since the thickness of the toner image on the transfer material is small, the unevenness is small and the toner image is not easily damaged by external force, and thus the formed image has high durability.

In particular, process black, in which toner images are laminated on a transfer material using three color toners of cyan, magenta and yellow, tends to have a large toner image thickness with ordinary toner, and the image quality is high. However, by suppressing the TMA of each color to a low level, the thickness of the toner image on the transfer material can be made sufficiently small, so that high image quality can be achieved. In order to obtain a vivid coloration of process black, the image area ratio is 10%.
When forming process black in the 0% region, the TMA of each color is preferably 0.10 mg or more, more preferably 0.12 mg or more, and still more preferably 0.15 mg or more.

Of course, an image area ratio of 1
Even when a solid image of 00% is to be obtained, or when a solid image having an image area ratio of 100% is to be obtained by other single-color toner, the conventional toner has a considerable thickness and the texture is impaired. However, by keeping TMA low, the thickness of the toner image on the transfer material can be made sufficiently small, and high image quality can be achieved.
Therefore, when obtaining a solid image having an image area ratio of 100% with black toner, the TMA is 0.10.
mg or more, more preferably 0.1 mg or more.
It is 2 mg or more, more preferably 0.15 mg or more, and the same applies to a solid image with an image area ratio of 100% using another single color toner.

[0093]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Preparation of Toner 1) Preparation of Flushing Pigment <Magenta Flushing Pigment> Polyester resin (bisphenol A-type polyester: bisphenol A ethylene oxide adduct-cyclohexanedimethanol-terephthalic acid, weight average molecular weight: 11,000, number average molecular weight : 3,500, Tg: 65 ° C), 70 parts by weight of a magenta pigment (CI Pigment Red 57: 1) and 75 parts by weight of a water-containing paste (40% by weight of a pigment) were put into a kneader-type kneader and mixed. Heated. Kneading was continued at 120 ° C., and after the water phase and the resin phase were separated, water was removed. The resin phase was kneaded to remove water, and dewatered to obtain a magenta flushing pigment.

<Cyan flushing pigment> A cyan flushing pigment was prepared in the same manner as the magenta flushing pigment except that the water-containing paste for magenta pigment was replaced with a water-containing paste (pigment blue 15: 3) (pigment content: 40% by weight). I got

<Yellow Flushing Pigment> A yellow flushing pigment was obtained in the same manner as the magenta flushing pigment except that the water-containing paste for magenta pigment was replaced with a water-containing paste (pigment yellow 17) (pigment content: 40% by weight). Was.

2) Production of Colored Particles <Production Example 1 of Colored Particles> Polyester resin (bisphenol A-type polyester: bisphenol A ethylene oxide adduct-cyclohexanedimethanol-terephthalic acid, weight average molecular weight: 11,000, number average) (Molecular weight: 3500, Tg: 65 ° C.) 66.7 parts by weight ・ The above magenta flushing pigment (pigment content: 30% by weight) 33.3 parts by weight The above components are melt-kneaded by a Banbury mixer, cooled, and then finely pulverized by a jet mill. And classification by a pneumatic classifier, and the conditions of pulverization and classification were changed to obtain colored particles A, B, J, T and U having respective particle size distributions shown in Table 1.

The particle size and particle size distribution of the particles were measured using a Coulter Counter T manufactured by Coulter Counter.
It was measured using Form A-II. At this time, when the average particle diameter of the toner (colored particles) exceeds 5 μm, 100 μm
Using an aperture tube of 5 μm or less, measurement was performed with an aperture diameter of 50 μm, and when measuring the number distribution of particles of 1 μm or less, measurement was performed with an aperture diameter of 30 μm (hereinafter, particle diameter and particle diameter). The same applies to the measurement of the particle size distribution).

<Preparation Example 2 of Colored Particles> Colored particles D shown in Table 1 were obtained in the same manner as in Preparation Example 1 of the color particles, except that the magenta flushing pigment was replaced with a cyan flushing pigment. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Preparation Example 3 of Colored Particles> The same procedure as in Preparation Example 1 of colored particles was carried out except that the polyester resin was 50 parts by weight, and 25 parts by weight of the magenta flushing pigment was replaced by 50 parts by weight of the yellow flushing pigment. Thus, colored particles E shown in FIG. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 4 of Colored Particles> Polyester resin was 90 parts by weight, and magenta flushing pigment was 25 parts by weight of carbon black (average primary particle diameter: 40 nm).
Colored particles C shown in Table 1 were obtained in the same manner as in Production Example 1 of the colored particles except that the amount was changed to parts by weight. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 5 of Colored Particles> The polyester resin was used in an amount of 73.3 parts by weight, and the magenta flushing pigment was used in an amount of 2 parts by weight.
Except for using 6.7 parts by weight, colored particles F shown in Table 1 were obtained in the same manner as in Production Example 1 of colored particles. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 6 of Colored Particles> The polyester resin was used in an amount of 83.4 parts by weight, and the magenta flushing pigment was used in an amount of 1 part by weight.
Except for using 6.6 parts by weight, colored particles K shown in Table 1 were obtained in the same manner as in Production Example 1 of colored particles. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 7 of Colored Particles> Colored particles L shown in Table 1 were prepared in the same manner as in Production Example 1 of Colored Particles except that the polyester resin was 80 parts by weight and the magenta flushing pigment was 20 parts by weight. Obtained. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 8 of Colored Particles> The polyester resin was used at 86.7 parts by weight, and the magenta flushing pigment was used at 1
Except for using 3.3 parts by weight, colored particles P shown in Table 1 were obtained in the same manner as in Production Example 1 of colored particles. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 9 of Colored Particles> A polyester resin was used in an amount of 73.3 parts by weight, and a cyan flushing pigment was used in an amount of 2 parts by weight.
Except for using 6.7 parts by weight, colored particles H shown in Table 1 were obtained in the same manner as in Production Example 2 of colored particles. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 10 of Colored Particles> Colored particles N shown in Table 1 were prepared in the same manner as in Production Example 2 of Colored Particles except that the polyester resin was 80 parts by weight and the cyan flushing pigment was 20 parts by weight. Obtained. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 11 of Colored Particles> The polyester resin was 86.7 parts by weight, and the cyan flushing pigment was 1
Colored particles R shown in Table 1 were obtained in the same manner as in Production Example 2 of the colored particles except that the amount was 3.3 parts by weight. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Preparation Example 12 of Colored Particles> The polyester resin was 60 parts by weight, and the yellow flushing pigment was 40 parts by weight.
Except for the weight part, the same as in Production Example 3 of the colored particles,
Colored particles I shown in Table 1 were obtained. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 13 of Colored Particles> Table 1 shows the same procedures as in Production Example 3 of colored particles, except that the polyester resin was 73.3 parts by weight and the yellow flushing pigment was 26.7 parts by weight. Colored particles O were obtained. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 14 of Colored Particles> Table 1 shows the same procedures as in Production Example 3 of colored particles, except that 83.3 parts by weight of the polyester resin and 16.7 parts by weight of the yellow flushing pigment were used. Colored particles S were obtained. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 15 of Colored Particles> Colored particles G shown in Table 1 were obtained in the same manner as in Production Example 4 of Colored Particles, except that 93 parts by weight of the polyester resin and 7 parts by weight of carbon black were used. Was. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 16 of Colored Particles> Colored particles M shown in Table 1 were obtained in the same manner as in Production Example 4 of Colored Particles, except that 96 parts by weight of polyester resin and 4 parts by weight of carbon black were used. Was. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

<Production Example 17 of Colored Particles> Colored particles Q shown in Table 1 were obtained in the same manner as in Production Example 4 of Colored Particles, except that 97 parts by weight of the polyester resin and 3 parts by weight of carbon black were used. Was. The conditions for pulverization and classification were adjusted so as to obtain the particle size distribution shown in Table 1.

Table 1 below shows the colored particles A obtained above.
In addition to the description regarding the particle size of ~ U, the pigment concentration C (%) in each colored particle, the true specific gravity a of each colored particle, aDC calculated from these values and the volume average particle size D (μm), and Average particle size of dispersed pigment particles in binder resin (equivalent circle diameter:
μm) is also described.

[0116]

[Table 1]

3) Preparation of Toner for Developing Electrostatic Latent Image The average particles of primary particles obtained by subjecting each of the colored particles A to U to a surface-hydrophobizing treatment with hexamethyldisilazane (hereinafter may be abbreviated as “HMDS”). Silica with 40 nm diameter (Si
O ₂ ) Fine particles, primary particles which are a reaction product of metatitanic acid and isobutyltrimethoxysilane, average particle size of 20 nm
And the meta-titanate compound fine particles are added so that the coverage of each colored particle on the surface is 40%, and mixed with a Henschel mixer to form toners A to A for developing electrostatic latent images.
U was produced (the symbols A to U attached to the obtained toners for developing electrostatic latent images correspond to the symbols A to U of the coloring particles used). Here, the coverage of the colored particles on the surface is the value F obtained by the above-mentioned equation (2).
(%).

Example of Carrier Production A methanol solution containing 0.1 part by weight of γ-aminopropyltriethoxysilane was added to 100 parts by weight of Cu—Zn ferrite fine particles having a volume average particle diameter of 40 μm, and coated with a kneader. Distilled, another 120
C. for 2 hours to completely cure the silane compound. The particles were added to a perfluorooctylethyl methacrylate-methyl methacrylate copolymer (copolymerization ratio: 40:
60) was dissolved in toluene, and the mixture was coated with a resin using a vacuum reduced-pressure kneader such that the coating amount of the perfluorooctylethyl methacrylate-methyl methacrylate copolymer was 0.5% by weight. Resin-coated carriers used in the following Examples and Comparative Examples were produced.

[Example 1] Resin-coated carrier; 100
4 parts by weight of toner A was mixed with the parts by weight using a V-type mixer to obtain a two-component developer of Example 1.

Example 2 A two-component developer of Example 2 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 4 parts by weight of toner B.

Example 3 A two-component developer of Example 3 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 4 parts by weight of toner C.

Example 4 A two-component developer of Example 4 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 4 parts by weight of toner D.

Example 5 A two-component developer of Example 5 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 4 parts by weight of toner E.

Example 6 A two-component developer of Example 6 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner F.

Example 7 A two-component developer of Example 7 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner G.

Example 8 A two-component developer of Example 8 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner H.

Example 9 A two-component developer of Example 9 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner I.

Example 10 A two-component developer of Example 10 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner J.

Example 11 A two-component developer of Example 11 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner K.

Comparative Example 1 A two-component developer of Comparative Example 1 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner L.

Comparative Example 2 A two-component developer of Comparative Example 2 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner M.

Comparative Example 3 A two-component developer of Comparative Example 3 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner N.

Comparative Example 4 A two-component developer of Comparative Example 4 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 5 parts by weight of toner O.

Comparative Example 5 A two-component developer of Comparative Example 5 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 6 parts by weight of toner P.

Comparative Example 6 A two-component developer of Comparative Example 6 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 6 parts by weight of toner Q.

Comparative Example 7 A two-component developer of Comparative Example 7 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 6 parts by weight of toner R.

Comparative Example 8 A two-component developer of Comparative Example 8 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 6 parts by weight of toner S.

[Comparative Example 9] A two-component developer of Comparative Example 9 was obtained in the same manner as in Example 1, except that 4 parts by weight of toner A was replaced by 4 parts by weight of toner T.

[Various Evaluation Test Methods] Using the two-component developers obtained in Examples 1 to 11 and Comparative Examples 1 to 9, the following various evaluation tests were performed on the toner.

In the following various evaluation tests, J-coated paper manufactured by Fuji Xerox Co., Ltd. was used as a transfer material, and Acolor 935 manufactured by Fuji Xerox Co., Ltd. was used as an image forming apparatus.
A modified machine (modified so that the voltage can be adjusted at the time of development by an external power source (hereinafter simply referred to as “Acolor 935 modified machine”)) is used, all at a temperature of 22 ° C. and a humidity of 55%.
The test was performed under the following environmental conditions. The image formation was performed while appropriately adjusting the image density to be in the range of 1.6 to 2.0.

<TMA> A solid image having an area ratio of 100% was formed, and the weight of the toner per unit area of the image portion (TMA: mg / cm ² ) was measured. As a specific measuring method, an unfixed solid image having an area of 10 cm ² was created on the transfer material, weighed, and then the unfixed toner on the transfer material was removed by air blowing. Is measured, and TMA is determined from the weight difference before and after the removal of the unfixed toner.
Was calculated.

<Image Density> A solid image having an area ratio of 100% was prepared, and the image density of the image portion was measured using X-Rite 404 (manufactured by X-Rite).

<Fine line reproducibility evaluation test> A line width of 5
A fine line image was formed so as to have a thickness of 0 μm, and the image was transferred and fixed on a transfer material. The fine line image of the fixed image on the transfer material was observed at a magnification of 175 times using a VH-6200 micro high scope (manufactured by Keyence Corporation). The specific evaluation criteria are as follows. Note that ◎ and ○ were regarded as acceptable ranges. ：: The fine line is uniformly buried with the toner and there is no disturbance at the edge. ：: The fine line is evenly buried with the toner, but slight jaggedness is observed at the edge. Δ: The fine line is almost uniformly buried by the toner, but the edge portion is notably jagged. X: The fine line is not uniformly filled with the toner. The jaggedness is very noticeable at the edge.

<Tone reproducibility evaluation test> Image area ratio 10
%, 20%, 30%, 40%, 50%, 60%, 70
%, 80%, 90%, and 100% gradation images were prepared, and X-Rite 404 (manufactured by X-Rite) was created.
The image density was measured according to, and the gradation was determined. The specific evaluation criteria are as follows. Note that ◎ and ○ were regarded as acceptable ranges. A: Very good gradation is obtained for all gradation images from the low image area ratio part to the high image area ratio part. ：: Good gradation is obtained for all gradation images from the low image area ratio to the high image area ratio. Δ: The tone reproduction area in the low image area ratio part is slightly narrow, and the tone property is somewhat unstable. X: The gradation reproduction area is narrow in the high / low image area ratio portion, and the gradation property is unstable.

<Highlight Part Granularity> Image area ratio 5%
And a 10% level gradation image was prepared, and the obtained image was visually observed to evaluate highlight portion granularity.
The specific evaluation criteria are as follows. Note that ◎ and ○ were regarded as acceptable ranges. ◎: Very good graininess at 5% and 10% ○: At 5%, the graininess is slightly poor, but the graininess is generally good. Δ: Granularity at 5% is poor. ×: Both 5% and 10% have poor graininess.

<Cleaning evaluation test> If no cleaning failure occurred after copying 3,000 sheets,
What occurred was rated as x.

The evaluation results of the developers (toners) of Examples 1 to 11 and Comparative Examples 1 to 10 are summarized in Table 2 below.

[0148]

[Table 2]

[Consideration of the results of Examples 1 to 11 and Comparative Examples 1 to 9] From the above results, it can be seen that the toner for developing an electrostatic latent image of the present invention has fine line reproducibility, gradation reproducibility and highlight. It is possible to form an image with good part granularity,
It turns out that it is also excellent in cleaning property. Example 10 in which the volume average particle size of the colored particles was slightly larger
In this case, fine line reproducibility, gradation reproducibility, and highlight portion granularity are slightly reduced as compared with the other examples, but within the allowable range. Further, in Example 11 having a low pigment concentration in which the aDC value was 25 or less, the texture of the image was slightly inferior due to the high TMA of the toner as compared with the other examples, but the granularity of the highlight portion was excellent. It can be said that the toner is sufficiently good as compared with the case where the conventional toner is used.

On the other hand, in Comparative Examples 1 to 8 in which the volume average particle size of the colored particles is large, although there is no problem in the cleaning property, the reproducibility of the thin line, which is the object of the present invention,
The gradation reproducibility and the graininess of highlight areas are low, and satisfactory image quality cannot be obtained. In Comparative Example 9,
Although fine line reproducibility, gradation reproducibility, and highlight portion granularity are good, the cleaning property is significantly deteriorated.
This is because the volume average particle diameter of the colored particles is small, and thus the obtained image itself can be good.
It is considered that the ratio of the colored particles having a particle size of μm or less is large, and it cannot be put to practical use after all.

Embodiment 12 Embodiments 2, 4, 5, and 3
Using the magenta, cyan, yellow and black developers prepared in the above, a full-color four-color copy test was performed. The copy test was performed using the Acol
The test was performed in an environment of a temperature of 22 ° C. and a humidity of 55% using an or935 modified machine. The image uniformity was determined by outputting a photographic image. The evaluation items are as shown below. The results are shown in Table 3 below.

<TMA> A solid image with an image area ratio of 100% for each of the toner single colors of magenta, cyan, yellow and black, and a process black with an image area ratio of 100% consisting of three colors of magenta, cyan and yellow. , And the weight of the toner per unit area of the image portion (TMA: mg / c)
m ² ) was measured. The specific measuring method is the same as in Examples 1 to 11.

<Image Density> Magenta, cyan,
A solid image with an image area ratio of 100% for each of the toner colors of yellow and black and a solid image of process black with an image area ratio of 100% composed of three colors of magenta, cyan, and yellow are respectively formed.
Using te404 (manufactured by X-Rite), the image density of the image portion was measured.

<Highlight Part Granularity> Image area ratio 5%
And a 10% level gradation image was prepared, and the obtained image was visually observed to evaluate highlight portion granularity.
The specific evaluation criteria are as follows. Note that ◎ and ○ were regarded as acceptable ranges. ◎: Very good graininess at 5% and 10% ○: At 5%, the graininess is slightly poor, but the graininess is generally good. Δ: Granularity at 5% is poor. ×: Both 5% and 10% have poor graininess.

<Image Uniformity> For the obtained photographic image, the degree of image uniformity due to the difference in image unevenness between the image portion and the non-image portion and between the high density portion and the low density portion is visually evaluated. did. The specific evaluation criteria are as follows. In addition, ○ was set as an allowable range. ：: Image uniformity equal to or higher than offset printing. Δ: Image uniformity slightly deteriorated as compared with offset printing. X: The image uniformity is clearly lower than in offset printing.

[Embodiment 13] Embodiments 6, 8, 9 and 7
Using the magenta, cyan, yellow, and black developers prepared in the above, a four-color full-color copy test was performed in the same manner as in Example 12. The results are summarized in Table 3 below.

Comparative Example 10 Comparative Examples 1, 3, 4, and 2
Using the magenta, cyan, yellow, and black developers prepared in the above, a four-color full-color copy test was performed in the same manner as in Example 12. The results are summarized in Table 3 below.

[Comparative Example 11] Comparative Examples 5, 7, 8 and 6
Using the magenta, cyan, yellow, and black developers prepared in the above, a four-color full-color copy test was performed in the same manner as in Example 12. The results are summarized in Table 3 below.

[0159]

[Table 3]

[Examples 12 to 13 and Comparative Examples 10 to 1]
Discussion of Result 1] From the above results, in Examples 12 and 13 in which a full-color image was obtained using the toner for developing an electrostatic latent image of the present invention, TM was obtained even when three colors were superimposed.
A can be suppressed to a low level, and excellent full-color images can be obtained, in which the highlight portion has excellent granularity and does not have a sense of incongruity due to image thickness (high image quality uniformity). In Example 13, since the pigment concentration was slightly lower and the TMA was a slightly higher value in order to make the image density sufficient, the image thickness was slightly larger, and the highlight region was higher than in Example 12. Both graininess and image quality uniformity are reduced.
However, it is within the allowable range, and it can be said that it is sufficiently good as compared with the case where the conventional toner is used.

On the other hand, in Comparative Examples 10 and 11 in which the volume average particle size of the colored particles was large, environmental stability, powder fluidity and fog were almost no problem, but fine line reproducibility, gradation reproducibility and image The uniformity is low and satisfactory image quality cannot be obtained.

[0162]

According to the present invention, fine line reproducibility, gradation reproducibility, and granularity of a highlight portion are good, and a high-quality image (particularly, a full-color image) can be formed, and cleaning properties are excellent. An electrostatic latent image developing toner, an electrostatic latent image developer, and a full-color image forming method using the same can be provided, which are particularly suitable for developing a digital latent image.

Further, according to the present invention, a toner for developing an electrostatic latent image, an electrostatic latent image developer, and a full-color image capable of achieving image quality equivalent to or better than a full-color image formed by offset printing A forming method can be provided.

Claims (3)

[Claims] 1. An electrostatic latent image developing toner comprising colored particles containing at least a binder resin and a colorant,
(A) The volume average particle diameter of the colored particles is 2.0 to 5.0 μm, the number of colored particles of 1.0 μm or less is 20% by number or less, and the number of colored particles of more than 5.0 μm is 10% by number or less. And (b) a toner for developing an electrostatic latent image, wherein the colorant is pigment particles. 2. An electrostatic latent image developer comprising at least a carrier and a toner, wherein the toner is the toner for developing an electrostatic latent image according to claim 1. 3. A latent image forming step of forming an electrostatic latent image on a latent image carrier, and a toner for forming a toner layer on a surface of a developer carrier disposed opposite to the latent image carrier. A layer forming step, a developing step of developing an electrostatic latent image on the latent image carrier with the toner layer, and a transfer step of transferring the developed toner image onto a transfer material, The toner for developing an electrostatic latent image according to claim 1, wherein in the image forming method for forming a full-color image by laminating toner images of four colors of cyan, magenta, yellow, and black, each of the four colors of toner is used. A full-color image forming method.