JP2001005210A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method where image formation without any fogging can be carried out even when an electrostatic latent image of a high resolution utilizing coherent light is used, reproduction of fine lines and gradation are carried out well and an image of a high resolution that is equivalent to or better than an image formed by offset printing is achieved. SOLUTION: In this image forming method, a latent image forming process forming a latent image utilizing the coherent light on a latent image carrier, a developing process where a toner image is obtained by developing the electrostatic latent image on a latent image carrier with toner and a transfer process where the formed toner image is transferred to transfer material are included. In this case, in this image forming method, the coherent light applied for the latent image forming process has a wave length of <=600 nm, the above mentioned toner is composed of coloring particles containing at least binding resin and a colorant and volume averaged grain size of the coloring is 2.0 to 5.0 μm, coloring particles with grain size <=1.0 μm are <=20% by number of particles and coloring particles with grain size >=5.0 μm are <=10% by number of particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method applied to an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc., and more particularly to an image forming method for obtaining an image from a digital electrostatic latent image. About the method.

[0002]

2. Description of the Related Art In electrophotography, a toner in a developer is adhered to an electrostatic latent image formed on a latent image carrier, transferred to a transfer material such as paper or plastic film, and then fixed by heating or the like. To 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, in the printers and copiers using the electrophotographic method, colorization has progressed in recent years, and electrostatic latent images have become finer due to improvement in resolution of the apparatus. 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.

On the other hand, Japanese Patent Application Laid-Open No. 5-19598 proposes to use a laser beam having a wavelength of 400 nm to 500 nm as a means for forming a high-resolution image having a high recording density. However, even when a latent image is created with a high resolution, the resolution of the obtained image is low when a conventional toner is used because the particle size is large.

Various improvements have been proposed for full-color toners. For example, JP-A-6-75430 and JP-A-7-77825 disclose that, 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 3. 7 μm,
The content of the toner having a particle diameter of 5.04 μm or less is more than 40% by number, and the toner having a particle diameter of 4 μm or less is 2%.
0 to 70% by number, toner having a particle diameter of 8 μm or more is 2-2.
It has been proposed to use a toner containing 6% by volume or less of toner having a particle diameter of 0% by volume or less and 10.08 μm or more.

Japanese Unexamined Patent Publication No. Hei 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 size of toner particles is 3.5 to 7.5 μm. Containing more than 35% by number of toner particles having a particle diameter of 5.04 μm or less, containing more than 15% by number of toner particles having a particle diameter of 4 μm or less, and
The toner having the above particle diameter is 2 to 20% by volume or less.
It has been proposed to use a toner containing 6% by volume or less of a toner having a particle diameter of 8 μm or more.

Further, Japanese Patent Application Laid-Open No. 8-227171 discloses a weight average particle diameter of 1 to 9 μm having a specified shape factor in order to improve transferability and cleaning properties and to improve deterioration of toner characteristics due to deterioration of external additives. It has been proposed to add 10 to 90 nm of inorganic powder and 30 to 120 nm of hydrophobized silicon compound fine powder to the above toner.

[0008] The small particle size toners studied in these documents have a weight average particle size of the toner particles of 3 to 7 µm, but the proportion of toner having a particle size of 5 µm or less is not necessarily large. There is a limit to the improvement of image quality even if is used. Further, there is no study on the relationship between the content of the toner having a particle diameter of 1 μm or less and various toner characteristics.

Further, in these toners, since the particle size distribution of the external additive is wide and the concept regarding the coverage of the toner particles is not specified, the volume average particle diameter is 5 μm.
When a toner having the following particle diameter is used, it is not possible to impart proper powder fluidity, powder adhesion, and chargeability to the toner, and it is not possible to achieve an improvement in image quality with a small particle diameter toner. In fact, the weight average particle diameter of the toner particles described in these examples is at least 6 μm.

On the other hand, the thickness of an image formed on a transfer material such as transfer paper (hereinafter, simply referred to as “image thickness”) is at most within a few μm in offset printing. Even if the particle diameter is as small as about 7 to 8 μm, in the case of process black formed with a full-color toner, at least three toner layers are overlapped, reaching from about ten and several μm to about 20 μm.
An image having such a large image thickness gives a visually uncomfortable feeling, and in order to achieve high image quality comparable to offset printing, the difference in image structure from offset printing is improved. Needs to be smaller. 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.

Further, when the particle diameter of the toner is further reduced, the non-electrostatic adhesion represented by van der Waals force increases, and the cohesion between the toners increases. Or the adhesion of the toner to the carrier or the surface of the latent image carrier is increased, so that the developability and transferability are deteriorated and the image density is reduced. Furthermore, the cleaning property of the toner remaining on the surface of the latent image carrier is increased. Or drop.

Further, since the charge exchange property between the toner and the carrier is reduced due to the deterioration of the powder characteristics due to the decrease in the diameter of the toner, the rise of the charge is reduced, and as a result, the charge distribution is widened and image quality defects such as fog are caused. Is more likely to occur,
Actually, high image quality has not been realized with a toner having a small particle diameter of 6 μm or less.

The above-mentioned problem of reducing the particle size of the conventional toner has been described in the case of obtaining a full-color image. There is a demand for improvement in tonality, and a reduction in image thickness leads to an improvement in image quality.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fog-free image formation even when a high-resolution electrostatic latent image using coherent light having a short light wavelength is used. It is an object of the present invention to provide an image forming method which has good reproducibility and gradation, and can achieve high-resolution image quality equal to or higher than an image formed by offset printing.

[0015]

Means for Solving the Problems In order to achieve the above object, the present inventors have proposed a latent image forming apparatus in which the wavelength of coherent light used in the step of forming a latent image (latent image forming step) is 600 nm or less. The particle size distribution of colored particles for developing an image (the portion of the toner excluding external additives, that is, what is generally called toner particles) was examined. As a result, the volume average particle diameter of the colored particles is 2.0 to 5.0 μm, 1.0 μm.
When the number of colored particles of m or less is 20% by number or less, and the number of colored particles exceeding 5.0 μm is 10% by number or less, fine line reproducibility, gradation, and highlight portion granularity of a high-resolution image obtained at a short wavelength are obtained. Was found to be extremely effective in achieving the improvement of

By controlling the volume average particle diameter of the colored particles to 5.0 μm or less, fine line reproducibility, gradation and highlight portion granularity in a high-resolution image obtained at a short wavelength are improved, and the colored particles are improved. Even if the pigment concentration in the inside is increased, fine line reproducibility, gradation, and highlight portion granularity do not decrease, and the pigment concentration in the colored particles is increased,
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 a small value. It is possible to obtain a high quality image comparable to that of printing or higher.

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 a certain amount of the colored particles having an excessively small particle size is present, it may cause a cleaning failure. In addition, when a certain amount of the large-diameter colored particles is present, the reproducibility of fine lines becomes insufficient, and a high-resolution image cannot be obtained. In the present invention, the lower limit of the volume average particle size is set to 2.0 μm, and colored particles of 1.0 μm or less are set to 2.0 μm in order to solve image quality problems such as fog and fine line reproducibility and cleaning problems.
The colored particles exceeding 5.0 μm are suppressed to 10% by number or less, respectively.

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 incongruity visually, which is equal to or higher than offset printing. At the same time, the cleaning property can be improved.

On the other hand, when an image is to be formed by using the electrostatic latent image developing toner used in the present invention,
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, sufficient image density can be achieved,
To ensure the water resistance, light resistance, or solvent resistance of the image, as the colorant contained in the colored particles, use pigment particles having high coloring power, and excellent water resistance, light resistance, or solvent resistance. Is preferred.

In the present invention, the particle size distribution of the colored particles is more preferably at least 75% by number of colored particles having a size of 4.0 μm or less. 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 following expression (2). 25 ≦ a · D · C ≦ 90 (2)

The wavelength of the coherent light used in the latent image forming step is preferably 350 nm or more and 600 nm or less in order to obtain a high-resolution image. The spot diameter at that time is preferably 50 μm or less.

The toner used in 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. In this case, the carrier has a volume average particle diameter of 50 μm or less. It is preferable to have a resin coating layer on the surface.

In the image forming method of the present invention, a latent image forming step of forming an electrostatic latent image on the latent image carrier is provided.
A developing step of developing an electrostatic latent image on the latent image carrier with toner, and a transfer step of transferring the developed toner image onto a transfer material, wherein at least cyan,
By laminating toner images of four colors of magenta, yellow and black, reproducibility of fine lines, disturbance of the image on the transfer material is improved, and image thickness is reduced, and an extremely high quality image is formed. can do.

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 or less, it can be obtained on the transfer material.
The thickness of the image is reduced, and extremely high quality images can be obtained.
This is preferable because Especially solid image with 100% area ratio
Weight of toner of each color in image is 1 cm^Two0.1 per
It is preferable that the amount be 0 to 0.40 mg.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a process of forming a latent image using coherent light on a latent image carrier, and developing a latent electrostatic image on the latent image carrier with toner to obtain a toner image. In an image forming method including a developing step and a transfer step of transferring a formed toner image onto a transfer material, the wavelength of coherent light used in the step of forming a latent image is 600 nm or less, and the toner Is composed of colored particles containing at least a binder resin and a colorant, and the volume average particle diameter of the colored particles is 2.0 to 5.0 μm, and the number of colored particles of 1.0 μm or less is 20% by number or less. And 10% or less colored particles exceeding 5.0 μm.

[Image Forming Method] The image forming method of the present invention comprises a latent image forming step of forming an electrostatic latent image on a latent image carrier,
The method includes a developing step of developing an electrostatic latent image on the latent image carrier with toner, and a transferring step of transferring the developed toner image onto a transfer material. At that time, coherent light (laser) having a wavelength of 600 nm or less as an exposure light source for forming a latent image
Is used. Although any light source can be used as such an exposure light source, a semiconductor laser which can be significantly reduced in size compared to a gas laser is preferable.
It is extremely effective when using exposure light of nm or less, and further, exposure light of 450 nm or less. Examples of such a semiconductor laser include a gallium nitride-based semiconductor laser having a multi-quantum well structure and a laser whose wavelength is shortened by a nonlinear optical element. In the image forming apparatus of the present invention, since a laser having a wavelength of 450 nm or less can be used as a light source, the spread of a laser beam spot is reduced as compared with a conventional semiconductor laser, so that an extremely high-resolution image can be formed. Writing can be realized. That is, the resolution is 400 dpi or more, particularly, 600 dpi.
i, a remarkable effect appears at 1200 dpi or more. In addition, the spot diameter is 50 μm or less, and further 30 μm.
A laser beam of m or less, especially 20 μm or less is preferably used in that high-resolution image formation is performed. The spot diameter refers to the minor axis diameter of the spot. Further, the transfer step may include a transfer step using an intermediate transfer member.

(A) Particle Size and Size Distribution of Colored Particles As described above, the reproducibility and gradation of a fine line of a latent image in which the wavelength of coherent light used in the latent image forming step is 600 nm or less. In order to achieve the above, it is essential that the volume average particle size of the colored particles is at least 5.0 μm or less. 5.
If it exceeds 0 μm, the ratio of coarse particles increases, and fine line reproducibility and gradation deteriorate. The term “reproducibility of fine lines” in the present invention mainly means 30 to 60 μm, preferably 3 to 60 μm.
This means whether or not a fine line having a width of 0 to 40 μm can be faithfully reproduced, and also takes 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.
When the particle size is less than 0 μm, various problems associated with the deterioration of powder characteristics such as deterioration of powder fluidity, developability, or transferability of toner and deterioration of cleaning property of toner remaining on the latent image carrier surface are reduced. May occur.

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 used in the present invention may be further adjusted so as to faithfully reproduce minute dots required for reproducing extremely high-light portions of an obtained image. In the colored particles, the colored particles having a size of 1.0 to 2.5 μm are preferably 5 to 50% by number, more preferably 10 to 45% by number. When 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 during development tends to occur,
Colored particles having a relatively small diameter of 1.0 to 2.5 μm are less likely to be consumed, and disadvantages such as fogging and poor cleaning at the time of copying a large number of sheets are likely 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 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.

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. Further, the molecular weight distribution may have two or more peaks.

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 Acid ester polymers, polyester polymers, epoxy resins and the like can be preferably used. Examples of the styrene-based polymer, (meth) acrylate-based polymer, and styrene- (meth) acrylate-based polymer include the following styrene-based monomers, (meth) acrylate-based monomers, and other acrylic or methacrylic-based monomers A polymer obtained by polymerizing one or more monomers appropriately selected from a vinyl ether monomer, a vinyl ketone monomer, an N-vinyl compound monomer and the like is preferably 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 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 method is extremely effective for the toner used in 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 used in the present invention, the colored particles have a volume average particle diameter of 5 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, a secondary color such as red or green or a tertiary color such as process black is expressed. The color development of the lower layer may be alienated by the colored particles of, and good color reproduction may not be achieved. However, when the average particle diameter of the dispersed particles in the binder resin is set to 0.3 μm or less in circle equivalent diameter, this problem is caused. Can be solved.

As described above, the toner used in the present invention has a small particle size, and it is difficult to obtain a sufficient image density with the same pigment concentration as the conventional toner having a larger particle size. Even if the toner used in the present invention has a small particle size, its volume average particle size ranges from 2.0 μm to 4.5 μm. There is also a large difference in the weight (TMA). Therefore,
It is desirable that the necessary pigment concentration is set 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 desirably satisfies the following relational expression (2). 25 ≦ a · D · C ≦ 90 (2)

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, when the amount of toner formed at the time of development is increased, a difference in image gloss is generated, the thickness of the image is increased, the reproducibility of fine lines is reduced, and the transferability is also reduced, although the angle of cut is reduced. Absent.

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 (2-1) to (2-4) are satisfied for each color. Cyan: 25 ≦ a · D · C ≦ 90 (2-1) Magenta: 25 ≦ a · D · C ≦ 60 (2-2) Yellow: 30 ≦ a · D · C ≦ 90・ ・ (2-3) Black: 25 ≦ a ・ D ・ C ≦ 60 (2-4)

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. In the present invention, the pulverization method is preferable. Here, the pulverization method means that after pre-mixing the binder resin and the colorant, and other additives as necessary, melt-knead with a kneader, pulverize after cooling, classify and adjust to a specified particle size distribution. It is.

[Other Additives] In the present invention, it is preferable to add an external additive for the purpose of controlling charging.
Examples of the material of the inorganic fine powder that can be used as an external additive include metal oxides such as titanium oxide, tin oxide, zirconium oxide, tungsten oxide, and iron oxide; nitrides such as titanium nitride; silicon oxide; and titanium compounds. Can be 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, ultrafine particles having an average primary particle diameter of 30 nm or more and 200 nm or less, 5 nm or more and 30 nm or less.
And ultra-fine particles having a primary particle average particle diameter of less than 0.1%.

The ultrafine particles have a function of reducing the adhesion between the colored particles or between the colored particles and the latent image carrier or the carrier, and preventing the deterioration of the developing property, the transferring property or the cleaning property. The average primary particle size of the ultrafine particles is 3
0 to 200 nm, more preferably 35 to 150 nm, still more preferably 35 to 10 nm.
0 nm 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 which can control the charge of the toner well and can reduce the adhesion to the carrier and the latent image carrier 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, and 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 additive is too large, free (not adhered to the colored particles) external additive is generated, and the latent image carrier and the carrier surface are contaminated with the external additive. It will be easier. 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 (1).

F = √3 · D · ρ _t · (2π · d · ρ _a ) ⁻¹ · C × 100 (1) (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 coating ratio of the external additive to the surface of the colored particles determined by the above formula (1) 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 covering rate Fa of the ultrafine particles is preferably 20 to 80%, more preferably 30 to 60%.

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

When the total coverage of all external additives exceeds 100%, a large amount of free external additives is generated, and the latent image carrier and the surface of the carrier 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%.

It is more preferable that the relationship between the ultrafine particle coverage Fa (%) and the ultrafine particle coverage Fb (%) satisfies the following expression (3). 0.5 ≦ Fb / Fa ≦ 4.0 (3) Outside this range, the effect of adding ultrafine particles or ultrafine particles is difficult to obtain, 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 used in the present invention has color reproducibility,
If necessary, a charge control agent, a release agent, and the like may be added in a range that does not affect the transparency. Examples of the charge control agent include a chromium azo dye, an iron azo dye, an aluminum azo dye, a salicylic acid metal complex, and an organic boron compound. 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.

(D) Relationship between charge amount q and particle size d (q / d
Value) In the toner used in the present invention, it is preferable to appropriately control the charge state of each colored particle. That is, not the charge amount of the toner as a whole but the charge state of each toner particle greatly affects the obtained image. On the other hand, since the particle size of each toner particle also has a large effect on image quality, the relationship with the image quality cannot be sufficiently explained by defining only the frequency distribution of the charge amount of each toner particle. Therefore, in the toner of the present invention, it is preferable that the relationship between the charge amount and the particle size of each toner particle is specified appropriately.

That is, under the environment of a temperature of 20 ° C. and a humidity of 50%, the charge amount of the toner is q (fC), and the particle diameter of the toner is d.
When represented as (μm), it is preferable that the peak value in the frequency distribution of the q / d value is 1.0 or less and the bottom value is 0.005 or more. As the q / d value, in the case of a positively charged toner, the above-described numerical values are applied as it is, but in the case of a negatively charged toner, the value of the charge amount q (fC) of the toner is reversed. Later, the above numerical provisions will apply.

The reason why the measurement environment of the charge amount is set to the environment of a temperature of 20 ° C. and a humidity of 50% is to define the charge amount in a standard environment which is generally room temperature. It is because it is the best in achieving. That is, a toner that satisfies the above-described conditions in such a standard environment has a large charge amount distribution suitable for obtaining high image quality, which is the object of the present invention, even when environmental conditions are slightly different. It does not come off, and can exhibit high performance very stably. Of course, it is needless to say that the toner having the above-mentioned charge amount distribution in a high-temperature high-humidity or low-temperature low-humidity environment is preferable.

When the q / d value of each toner is measured and its frequency distribution is graphed, the distribution is approximately a normal distribution having an upper limit and a lower limit. In the present invention, the q / d value at the point that is the top of the graph is the peak value, and the q / d value at the point that is the lower limit (in the case of negatively charged toner, the lower limit after reversing the sign) is the bottom. Value.

In the toner used in the present invention, the peak value in the frequency distribution of the q / d value is preferably 1.0 or less, more preferably 0.80 or less.
More preferably, it is 0.70. When the peak value exceeds 1.0, even if the frequency distribution is set to be narrower, the adhesion of the toner to the carrier or the surface of the photoreceptor is increased, so that the developability and transferability are deteriorated and the image density is reduced. Further, there is a possibility that the cleaning property of the toner remaining on the surface of the photoreceptor may be deteriorated, which is not preferable. When the peak value is set to exceed 1.0 and the charge distribution is set to be wide, in addition to the above-described problems,
Since the variation in the chargeability of each toner becomes large, the developability and the transferability may be non-uniform.

On the other hand, if the q / d value is too close to 0, or the value is opposite in polarity (ie, toner of opposite polarity), the image portion may be missing or the non-image portion may be fogged. . Therefore, it is desired to keep the bottom value in the frequency distribution of the q / d value at a certain value or more.
It is preferably at least 005, more preferably 0.15.
It is preferably at least 01, more preferably at least 0.02, particularly preferably at least 0.025.

In the frequency distribution of the q / d value,
There is no need to particularly define the value that is the upper limit (in the case of negatively charged toner, the upper limit of the absolute value). q
This is because the frequency distribution of the / d value generally indicates a normal distribution as described above, and the upper limit is naturally determined by specifying the peak value and the bottom value.

The frequency distribution of the q / d value is described in, for example,
It can be measured by a charge spectrograph method (hereinafter, referred to as "CSG method") described in JP-A-799958. Hereinafter, a specific measurement method will be described.

FIG. 1 is a schematic perspective view of a measuring device 10 for measuring the frequency distribution of q / d values by the CSG method.
The measuring device 10 includes a cylindrical body 12, a filter 14 for closing the lower opening, a mesh 16 for closing the upper opening, and a sample supply projecting from the center of the mesh 16 to the inside of the body 12. A cylinder 18, a suction pump (not shown) for sucking air from a lower opening of the body 12, and a body 1
And an electric field generating device (not shown) for applying an electric field E from the side of the second electric field.

The suction pump is set so as to uniformly suck air inside the body 12 through the filter 14 at the lower opening of the body 12. As a result, air flows from the mesh 16 in the upper opening, and a laminar flow with a constant air flow rate Va is generated vertically downward inside the body 12. Further, a uniform and constant electric field E is provided in the direction orthogonal to the air flow by the electric field generator.

The toner particles to be measured are gradually dropped (dropped) from the sample supply tube 18 into the body 12 in the above state. Sample supply cylinder 1
The toner particles coming out of the sample outlet 20 at the tip 8 fly vertically downward under the influence of the laminar air flow unless affected by the electric field E, and the center O of the filter 14
(At this time, the distance k between the sample outlet 20 and the filter 14 is the straight flight distance of the toner). The filter 14 is made of a coarse polymer filter or the like, and allows air to sufficiently pass therethrough, but does not allow toner particles to pass therethrough.
It remains on the filter 14. However, in the case of a charged toner, the toner is affected by the electric field E and reaches the filter 14 with a position shifted from the center O in the direction of travel of the electric field E (point T in FIG. 1). By measuring the distance (displacement) x between the point T and the center O and obtaining the frequency distribution, the frequency distribution of the q / d value can be obtained (in the present invention, the peak is actually obtained by image analysis). Values and bottom values were determined directly.)

More specifically, the relationship between the displacement x (mm) obtained by the measuring device 10 as described above, the charge amount q (fC) of the toner, and the particle size d (μm) of the toner will be described. Is represented by the following equation (4). q / d = (3πηVa / kE) × x (4) In equation (4), η is the viscosity of air (kg / m · sec.),
Va represents the air flow velocity (m / sec.), K represents the straight flight distance (m) of the toner, and E represents the electric field (V / m).

In the present invention, each condition of the expression (4) is
The measurement is performed by setting each condition of the measuring apparatus 10 shown in FIG. 1 so that the following numerical values are obtained. Air viscosity η = 1.8 × 10 ^{] 5} (kg / m · sec.) Air flow rate Va = 1 (m / sec.) Direct flight distance of toner k = 10 (cm) Electric field E = 190 V / cm

By substituting the above values into equation (4), the following is obtained. q (fC) / d (μm) ≒ 0.09 · x

When the toner particles to be measured are dropped into the sample supply cylinder 18, the toner needs to be charged in advance. The reason why the q / d value of the toner needs to have the above frequency distribution is when actually developing the electrostatic latent image, and the toner to be measured is mixed with a carrier to form a two-component developer. The purpose of the present invention is to perform shaking or the like under conditions similar to the apparatus conditions and to provide the results to the measurement of the frequency distribution of q / d values.

Therefore, in the present invention, the charging conditions of the toner particles to be measured are defined as follows (of course, the toner used when actually developing the electrostatic latent image is sampled directly from an apparatus or the like). Is measured by the above q / d
More preferably, the condition of the frequency distribution of the values is satisfied).

In the present invention, the electrostatic latent image developer actually used, which is composed of a toner and a carrier, is charged into a glass bottle, and stirred for 2 minutes with a turbulator shaker to obtain a q / d value. Was used for measurement of the frequency distribution.

In this way, the frequency distribution of the q / d value can be obtained. Of course, in the present invention, the frequency distribution of the q / d value can be obtained by a method other than the CSG method as described above, but the CSG method has a small error.

[Electrostatic Latent Image Developer] The toner used in the present invention is preferably mixed with a carrier and used as a two-component electrostatic latent image developer. It can also be used as a one-component electrostatic latent image developer without using a carrier.

The carrier preferably used together with the toner used in the present invention is not particularly limited, and magnetic particles such as iron powder, ferrite, iron oxide powder, nickel, and the like are used as a core material, and the surface thereof is used as a carrier. A styrene resin, vinyl resin, ethyl resin, rosin resin,
Coated resin type carrier particles formed by forming a resin coating layer by coating with a known resin such as polyester resin or methyl type resin, or magnetic material dispersed type carrier particles obtained by dispersing magnetic fine particles in a binder resin. And the like.

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 particle diameter of the carrier is preferably 50 μm or less as a volume average particle diameter, more preferably 10 to 40 μm, and still more preferably 15 to 35 μm.
It is. By reducing the volume average particle diameter of the carrier to 50 μm or less, it is possible to improve background contamination and density unevenness resulting from charge rise, deterioration of charge distribution, and decrease in charge amount due to reduction in toner (colored particle) particle diameter. Can be.

The mixing ratio between the toner and the carrier is preferably in the range of 1: 100 to 20: 100 by weight, more preferably in the range of 2: 100 to 15: 100, and still more preferably in the range of 3: 100 to 10: 100. The range is 100.

Further, at least cyan,
In an image forming method of forming a full-color image by laminating toner images of four colors of magenta, yellow, and black, if the image forming method of the present invention is applied, the obtained image has fine line reproducibility and gradation. It is good and free of fogging, and the toner particle size is small, so fine line reproducibility, gradation and highlight part granularity are good, and fine line reproduction even when the pigment concentration in the colored particles is high The toner density per unit area of the image formed on the transfer material can be reduced by increasing the pigment concentration in the colored particles without causing deterioration in the toner properties, 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 achieve a high image quality comparable to or higher than that of offset printing without giving a visually unnatural feeling. Can. 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 suppressing the TMA to a low value in this manner, the thickness of the toner image on the transfer material can be reduced, and high image quality comparable to offset printing can be achieved without any visual discomfort. 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 of three colors, cyan, magenta and yellow, are laminated on a transfer material, the thickness of the toner image tends to be large 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, the area ratio is 100
% When a solid image of 100% is to be obtained, or when a solid image having an area ratio of 100% is to be obtained with a 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, so that high image quality can be achieved. Therefore, the TMA is preferably 0.10 mg or more, more preferably 0.12 mg or more, and still more preferably 0.15 mg or more when a solid image having an area ratio of 100% is to be obtained with black toner. The same applies to the case of a solid image with an area ratio of 100% using another single color toner.

The wavelength of the coherent light used in the present invention is 60
As the latent image carrier for electrophotography used in the exposure step of 0 nm or less, a latent image carrier having a photosensitive layer having a single layer structure or a latent image carrier having a photosensitive layer having a laminated structure formed on a conductive substrate is used. be able to. In particular, a layer in which a photosensitive layer having a laminated structure in which at least a charge generation layer and a charge transport layer are sequentially formed is preferably used. As the conductive substrate, for example, aluminum, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium,
A metal plate, a metal drum, a metal belt using a metal or alloy such as gold or platinum, or a conductive polymer, a conductive compound such as indium oxide, or a metal or alloy such as aluminum, palladium, or gold is applied or deposited. Alternatively, a laminated paper, plastic film, belt or the like is used. Further, if necessary, the surface of the conductive substrate
As long as the image quality is not affected, various treatments, for example, anodized coating treatment on the surface, thermal hydroxylation treatment, chemical treatment, coloring treatment, or irregular reflection treatment such as graining can be used.

In the charge generation layer of the present invention, examples of charge generation substances include azo pigments, quinone pigments, perylene pigments, indigo pigments, thioindigo pigments, and the like.
Various organic pigments such as bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, quinoline pigments, lake pigments, azo lake pigments, anthraquinone pigments, oxazine pigments, dioxazine pigments, triphenylmethane pigments, Various dyes such as azulenium dyes, squarium dyes, pyrylium dyes, triallylmethane dyes, xanthene dyes, thiazine dyes, cyanine dyes, and more, amorphous selenium, trigonal selenium, tellurium, selenium-tellurium alloy ,
Inorganic materials such as cadmium sulfide, antimony sulfide, zinc oxide, and zinc sulfide are used. Among them, aromatic condensed ring pigments, perylene pigments, and azo pigments are used for sensitivity, electrical stability, and resistance to irradiation light. It is preferable in terms of photochemical stability. When using a charge generating substance, the above substances are used alone or in combination of two or more.

The charge generation layer is formed by forming the charge generation material by vacuum evaporation or by applying a coating liquid in which the charge generation material is dispersed in a binder resin in an organic solvent.
At the time of the application, as a binder resin in the charge generation layer coating liquid, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl acetal such as partially acetalized polyvinyl acetal resin in which a part of butyral is modified with formal or acetoacetal, etc. Resin, polyamide resin, polyester resin, modified ether type polyester resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, silicone resin Phenolic resin, phenoxy resin, melamine resin, benzoguanamine resin, urea resin, polyurethane resin, poly-N-vinylcarbazole resin, polyvinylanthracene resin, polyvinylpyrene and the like are used. Among these resins, polyvinyl acetal-based resins, vinyl chloride-vinyl acetate-based copolymers, phenoxy resins or modified ether-type polyester resins, in particular, improve the dispersion of the pigment, and do not coagulate the pigment for a long time. The dispersion coating solution is preferable because it is stable, and a uniform coating is formed using the coating solution,
As a result, the electrical characteristics can be improved and the image quality defects can be reduced. However, the resin is not limited to these as long as it can form a film in a normal state. These binder resins are used alone or in combination of two or more. The mixing ratio of the charge generation material to the binder resin is preferably in the range of 5: 1 to 1: 2 by volume.

The thickness of the charge generation layer is usually 0.01 to 5 μm.
m, and preferably 0.1 to 2.0 μm. If the thickness is less than 0.01 μm, it is difficult to form a uniform charge generating layer, while if it exceeds 5 μm, the electrophotographic properties tend to be significantly reduced.

Further, a stabilizer such as an antioxidant and a light stabilizer can be added to the charge generating layer, if necessary. Examples of the antioxidant include an antioxidant such as a phenol-based, sulfur-based, phosphorus-based, and amine-based compound. Examples of the light stabilizer include bis (dithiobenzyl) nickel, nickel di-n-butylthiocarbamate, and the like.

In the present invention, an undercoat layer may be provided between the charge generation layer and the conductive substrate. Examples of the binder resin used for the undercoat layer include the following.
Polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polyurethane resin, melamine resin, benzoguanamine resin, polyimide resin, polyethylene resin, polypropylene resin, polycarbonate resin, acrylic resin, methacrylic resin, vinylidene chloride resin, polyvinyl acetal resin, chloride Vinyl-vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, nitrocellulose, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, polyacrylic acid, polyacrylamide, zirconium chelate compound, titanyl chelate compound, Known materials such as a titanyl alkoxide compound, an organic titanyl compound, and a silane coupling agent can be used. These materials can be used alone or in combination of two or more. Further, fine particles such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, barium titanate, and silicone resin can be mixed. As an application method for forming the undercoat layer, a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like is employed. The thickness of the undercoat layer is from 0.01 to 10 μm, preferably from 0.05 to 2 μm.

Examples of the charge transport material in the charge transport layer include low molecular weight compounds such as pyrene, carbazole, hydrazone, oxazole, oxadiazole, pyrazoline, arylamine, arylmethane, and benzidine. And various organic compounds such as thiazole, stilbene, butadiene and aromatic polycyclic compounds. Further, as the polymer compound, for example, poly-
N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin,
Triphenylmethane polymer or polysilane is used. Among them, among the triphenylamine compounds and triphenylmethane compounds, those having no unsaturated bond or aromatic ring conjugated to a phenyl group are preferable because they do not easily emit fluorescence, and those other than the aromatic ring directly connected to the nitrogen element are preferable. Further, those containing at least one halogen element as a substituent are preferable because the quantum yield of fluorescence emission can be effectively reduced by the heavy atom effect. Further, a polymer containing these may be used.

Further, the charge transport polymer material may be formed alone, or may be formed by dispersing it in a known binder resin. Polymer charge transport materials and hydrazone-based charge transport materials,
A triarylamine-based charge transport material, a stilbene-based charge transport material, or the like may be used as a mixture. In particular, in the charge transport layer, the resolution is such that the number of absorption photons (N _A ) and the number of fluorescence emission photons (N _F ) of the charge transport layer satisfy the following expression (5), corresponding to the exposure wavelength to be used. It is preferred in that respect. _{N F ≦ 0.75 × N A ···} (5)

Further, a stabilizer such as a deactivator can be added to the charge transport layer, if necessary. Examples of the deactivator include bis (dithiobenzyl) nickel, di-n
-Nickel butylcarbamate and the like.

When a binder resin is used for forming the charge transport layer in the present invention, a high molecular polymer capable of forming an electrically insulating film is preferable. Examples of such a high-molecular polymer include polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile polymer, and chloride. Vinyl-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-
Formaldehyde resin, styrene-alkyd resin, poly-N-vinyl carbazole, polyvinyl butyral,
Examples include, but are not limited to, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenolic resin, polyamide, carboxy-methyl cellulose, vinylidene chloride-based polymer latex, polyurethane, and the like. These binder resins may be used alone or in combination of two or more. Particularly, polycarbonate, polyester, methacrylic resin and acrylic resin are excellent in compatibility with the charge transport material, solubility in a solvent, and strength. Is preferred.

Further, in addition to the above-mentioned binder resin, additives such as a plasticizer, a surface modifier, an antioxidant and a light deterioration inhibitor can be used. Examples of the plasticizer include biphenyl, biphenyl chloride, terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenylphosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, polypropylene, polystyrene, various fluorohydrocarbons, and the like. Examples of the antioxidant include an antioxidant such as a phenol-based, sulfur-based, phosphorus-based, and amine-based compound. Examples of the photo-deterioration inhibitor include benzotriazole-based compounds, benzophenone-based compounds, hindered amine-based compounds, and the like. The ratio of the charge transport material to the binder is used in the range of 2:10 to 10: 2, and preferably in the range of 3:10 to 10: 8 from the viewpoint of mobility and strength. The thickness of the charge transport layer is usually 5 to 50 μm, preferably 10 to 40 μm. If the thickness is less than 5 μm, charging becomes difficult, while if it exceeds 50 μm, the electrophotographic properties tend to be significantly reduced. Further, a conventionally known protective layer can be formed on the charge transport layer, if necessary.

[0120]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Production Example of Latent Image Carrier A zirconium compound (trade name:
A solution consisting of 10 parts by weight of ORGATICS ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.), 1 part by weight of a silane compound (trade name: A1110, manufactured by Nippon Unicar), 40 parts by weight of i-propanol and 20 parts by weight of butanol was applied by a dip coating method. It is applied and heated and dried at 150 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.1 μm. Next, a mixture of 8 parts by weight of a dibromoanthanthrone pigment as a charge generating material, 2 parts by weight of a carboxyl-modified vinyl chloride-vinyl acetate copolymer (trade name: VMCH, manufactured by Union Carbide) and 100 parts by weight of butanol was added to glass beads. With a sand mill for 1 hour, and the obtained coating solution is applied on the undercoat layer by a dip coating method.
The resultant was dried by heating at 10 ° C. for 10 minutes to form a charge generation layer having a thickness of about 1 μm.

Next, a benzidine compound (N, N'-diphenyl-N, N'-bis (3
-Methylphenyl) -1,1'-biphe
nyl-4,4'-diamin, (m-TBD)) 6
A coating solution obtained by dissolving 9 parts by weight of bisphenol (Z) polycarbonate and 85 parts by weight of monochlorobenzene was applied onto the above-mentioned charge generating layer,
For 60 minutes to form a charge transport layer having a thickness of about 20 μm. A latent image carrier was produced as described above.

The calculation of the number of absorption photons and the number of fluorescence emission photons in the charge transport layer is performed as follows. The measuring device includes Hitachi Fluorescence Spect.
oro Photometer 850 (manufactured by Hitachi, Ltd.) is used. As the sample for fluorescence measurement, a sample obtained by applying a coating solution containing the charge transport material used for forming the charge transport layer on a slide glass and drying by heating at 115 ° C. for 60 minutes is used. Further, the measurement was carried out by first measuring anthracene (purity 99.
5% or more · 1 × 10 ^-6 M in ethanol, 27% fluorescence quantum yield, determine the number of incident light photons relative to the Tokyo Kasei), and calculates the absorption photons number (N _A). The number of fluorescence photons (N _F ) is calculated from the measurement of the fluorescence spectrum. As a result, in the charge transport layer using the charge transport material (Compound No. 66), the absorption photon number (N _A ) was 3.56 × 10 ³ at a wavelength of 410 nm, and the fluorescence emission photon number (N _F ) is 1.63 × 1
0 ³ and satisfies the relationship of Expression (5).

A Color935 (manufactured by Fuji Xerox Co., Ltd.) was modified with an optical system so that a latent image could be written with a dye laser having a wavelength of 410 nm, and the latent image carrier obtained in the production example of a latent image carrier was mounted. -40 in the dark due to discharge
After being charged to 0 V, a latent image is written using a dye laser having a wavelength of 410 nm.

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. Heat to Kneading is continued at 120 ° C., and after the water phase and the resin phase are separated, water is removed. The resin phase is 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). Get.

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

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 ・ Magenta flushing pigment (pigment content: 30% by weight) 33.3 parts by weight

The above components were melt-kneaded by a Banbury mixer, cooled, then finely pulverized by a jet mill and classified by an air classifier, and the conditions of pulverization and classification were changed to change the colored particles M1 having the particle size distributions shown in Table 1 below. , M2.

<Production Example 2 of Colored Particles> Colored particles C shown in Table 1 below were prepared in the same manner as in Production Example 1 of the colored particles, except that the magenta flushing pigment was replaced with a cyan flushing pigment.
1. Obtain C2. The conditions for pulverization and classification are adjusted so as to obtain the particle size distribution shown in Table 1 below.

<Production Example 3 of Colored Particles> The same procedure as in Production Example 1 of colored particles was used 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. The colored particles Y1 and Y2 shown in Table 1 are obtained. The conditions for pulverization and classification are adjusted so as to obtain the particle size distribution shown in Table 1 below.

<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) 10
Colored particles K1 and K2 shown in Table 1 below are obtained in the same manner as in Production Example 1 of the colored particles, except that the parts are replaced by parts by weight. In addition,
The conditions for pulverization and classification are adjusted so as to obtain the particle size distribution shown in Table 1 below.

For each of the colored particles obtained as described above, the particle size distribution, the average dispersed particle size of the pigment particles, and the aDC
Are summarized in Table 1 below.

3) Preparation of Toner Each of the colored particles M1, C1, Y1, and K1 was subjected to surface hydrophobic treatment with hexamethyldisilazane, silica (SiO ₂ ) fine particles having an average primary particle diameter of 40 nm, and metatitanic acid. The primary particles having a mean particle diameter of 20 nm, which is a reaction product of isobutyltrimethoxysilane, and a metatitanate compound fine particle having a coverage of 40% on the surface of each colored particle.
And mixed with a Henschel mixer to prepare a toner. Further, M2, C2, Y2, and K2 were added to the respective colored particles so that the coverage of the surface of each colored particle was 30%. Each obtained toner is
The numbers of the used colored particles are used as they are.

Here, the coverage of the colored particles on the surface refers to the value F obtained by the above-mentioned equation (1).
(%). Table 1 below shows the total external additive coverage and the values obtained by measuring the peak value and the bottom value of q / d by the above-described method for each of the obtained toners.

[0135]

[Table 1]

Carrier Production Example 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 the mixture was coated with a kneader. Distilled off and 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. A resin-coated carrier used in the following Examples and Comparative Examples is manufactured.

[Preparation of Developer] Resin-coated carrier; 1
With respect to 00 parts by weight, 4 parts by weight of each of the obtained toners are mixed by a V-type mixer to obtain each two-component developer used in Examples and Comparative Examples.

[Various Evaluation Test Methods] Using the two-component developers obtained above, various evaluation tests of the following toners were performed. Here, in each of the two-component developers used, the toner numbers included in the examples are M1, C1, Y1, and K1 in the order of Examples 1, 2, 3, and 4, and the toner numbers included are M2, Those of C2, Y2, and K2 are referred to as Comparative Examples 1, 2, 3, and 4, respectively.

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.
Remodeling machine (Modification of latent image carrier and exposure device so that voltage can be adjusted during development with an external power supply (hereinafter simply referred to as "Acolor 935 remodeling machine"))
And under all environmental conditions of a temperature of 22 ° C. and a humidity of 55%. Further, the image formation is 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% is formed, and the weight of the toner per unit area of the image portion (TMA: mg / cm ² ) is 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.
Is calculated.

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

<Fine Line Reproducibility Evaluation Test> A fine line image was formed on a latent image carrier so as to have a line width of 30 μm, and the image was transferred and fixed on a transfer material. The image of the thin line of the fixed image on the transfer material is 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. ：: The fine line is uniformly buried with the toner and there is no disturbance at the edge. X: The fine line is not uniformly filled with the toner. The jaggedness is very noticeable at the edge.

<Gradation 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 prepared.
To measure the image density and judge the gradation. The specific evaluation criteria are as follows. A: Very good gradation is obtained for all gradation images from the low image area ratio part to the high image area ratio part. 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%
Then, a gradation image of a level of 10% and 10% is created, and the obtained image is visually observed to evaluate the highlight portion granularity.
The specific evaluation criteria are as follows. ：: Very good graininess at 5% and 10%. ×: Poor graininess at 5% and 10%.

The results of the above evaluations are summarized in Table 2 below.

[0146]

[Table 2]

[0147]

As described above, according to the present invention, 600n
By forming a latent image using a laser beam of m or less, the edge of the fine line becomes smooth, and by developing using a specific small diameter toner, a clear fine line can be obtained. Similarly, uniform dots can be obtained, so that an image with excellent halftone reproducibility can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a measuring device for measuring a frequency distribution of q / d values by a CSG method.

[Explanation of symbols]

 10: Measuring device 12: Body 14: Filter 16: Mesh 18: Sample supply cylinder 20: Sample outlet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 507L F-term (Reference) 2H005 AA08 AA21 AB02 AB10 CA21 CA26 CB10 CB13 DA01 EA05 EA07 EA10 FC01 2H030 AD01 BB02 BB23 BB24 BB44 2H076 AB05 AB09 DA39 EA01 2H077 BA10 DB13 DB14 DB15 EA03 EA24 GA13

Claims (11)

[Claims] A latent image forming step of forming a latent image on the latent image carrier using coherent light; and a developing step of developing an electrostatic latent image on the latent image carrier with toner to obtain a toner image. And a transfer step of transferring the formed toner image onto a transfer material, wherein the wavelength of the coherent light provided to the latent image forming step is 600 nm or less; It is composed of colored particles containing a resin and a colorant, and the volume average particle size of the colored particles is 2.0 to 5.0 μm, and the number of colored particles of 1.0 μm or less is 20% by number or less, and 5.0 μm. The number of colored particles exceeding 10% by number or less. 2. The toner according to claim 1, wherein
2. The image forming method according to claim 1, wherein m colored particles are in the range of 5 to 50% by number. 3. The image forming method according to claim 1, wherein the average particle diameter of the dispersed particles of the pigment particles in the colored particles is 0.3 μm or less in circle equivalent diameter. 4. The image forming method according to claim 1, wherein the toner is a color toner. 5. The image forming method according to claim 1, wherein said toner further comprises an external additive. 6. An ultrafine particle having an average primary particle diameter of 30 nm or more and 200 nm or less, comprising:
And ultra-fine particles having a primary particle average particle diameter of less than 0 nm, wherein the coverage of the external additive on the surface of the colored particles determined by the following formula (1) is as follows: Fb
6. The image forming method according to claim 5, wherein both of the coating rates are 20% or more, and a total of the coating rates of all the external additives is 100% or less. F = √3 · D · ρ _t (2π · d · ρ _a ) ⁻¹ · C × 100 (1) (where F is the coverage (%) and D is the volume average of the colored particles. Particle size (μm), ρ _t is the true specific gravity of the colored particles, d is the average primary 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). ) 7. The charge amount of the toner under the environment of a temperature of 20 ° C. and a humidity of 50% is q (fC), and the particle size of the toner is d (μ).
m), the peak value in the frequency distribution of the q / d value is 1.0 or less and the bottom value is 0.00
The image forming method according to any one of claims 1 to 6, wherein the number is 5 or more. 8. A full-color image according to claim 1, wherein four color toner images of cyan, magenta, yellow and black are laminated on a transfer material to form a full-color image. Image forming method. 9. A toner image transferred onto a transfer material in a transfer step, wherein the toner weight per color is 0.40 mg / cm.
The image forming method according to claim 1, wherein the number is ² or less. 10. The image forming method according to claim 1, wherein the wavelength of the coherent light used in the latent image forming step is 350 nm or more and 600 nm or less. 11. A spot diameter on a latent image carrier is 50 μm.
The image forming method according to claim 1, wherein: