JP2001005211A - Image forming method and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method and an image forming device that an image of high quality can be formed by applying sufficient electrification even in a case of small diameter toner. SOLUTION: In this image forming method, an electrifying process where a latent image carrier is electrified by an electrifying member, 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 the latent image carrier with toner and a transfer process where the formed toner image is transferred to transfer material are included. In this case, relating to this image forming method and this image forming device, 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 particles is 2.0 to 5.0 μm, coloring particles with grain size <=10 μm are <=20% by number of particles, coloring particles with grain size >=5.0 μm are <=10% by number of particles, the above mentioned electrifying process is a process where the above mentioned latent image carrier is electrified while the above mentioned electrifying member and the above mentioned image carrier keep a space in between.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming method and an image forming apparatus, and more particularly, to an electrophotographic method,
The present invention relates to an image forming method and an image forming apparatus applied to an electrostatic recording method, an electrostatic printing method, and the like.

[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.

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 Patent Application Laid-Open No. Hei 7-146589 discloses that in order to obtain an image excellent in highlight reproduction and fine line reproduction at high image density, the weight average particle diameter 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. Hei 8-227171 discloses a weight average particle size 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.

Although the small particle size toners studied in these documents have a weight average particle size of the toner particles of 3 to 7 μm, the ratio of the toner having a particle size of 5 μm or less is not necessarily large, and such toner particles are not so 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 size 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 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.

In order to meet the demand for higher resolution (fine line reproducibility, gradation improvement, etc.) in the future, it is necessary to further reduce the toner particle size and to have an appropriate particle size distribution.
If the particle size of the toner is further reduced, the non-electrostatic adhesion represented by Van der Waals force increases, and the cohesion between the toners increases. Since the adhesive force of the toner to the surface of the image carrier is increased, the developability and transferability are deteriorated, and the image density is reduced. Further, the cleaning property of the toner remaining on the surface of the latent image carrier is greatly reduced.

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 reduction 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.

[0013]

The present applicant has filed Japanese Patent Application No. Hei.
In the specification and drawings attached to Japanese Patent Application No. 0-219376, the toner is composed of colored particles containing at least a binder resin and a colorant, and the volume average particle size of the colored particles is 2.0 to 5.0 μm. There is proposed a toner in which colored particles having a size of 1.0 μm or less are 20% by number or less and colored particles having a size of more than 5.0 μm are 10% by number or less.

However, especially in a small-diameter toner,
When repeatedly forming a high-definition image, if there is a variation in charging, it tends to appear as an image defect.
The toner proposed above has a very small particle size, and the conventional organic photoreceptor has a fluctuation in the layer thickness of its photosensitive layer.When this is used, in a contact charging system such as a charging roller, When a large number of copies are made, the variation due to the charging of the surface is likely to be large, and a defect of an image defect may occur.

Further, when the particle size of the toner particles is reduced, the specific surface area is increased, so that the amount of the external additive per unit weight is increased, and the external additive is easily attached to the photoreceptor. In some cases, contamination of the charging member may cause poor charging.

Accordingly, the object of the present invention is to
Provided is an image forming method and an image forming apparatus capable of giving sufficient charge and forming a high-quality image even with a small-diameter toner proposed in the specification and the drawings attached to Japanese Patent Application No. 219376. It is in.

[0017]

The above object is achieved by the present invention described below. That is, the present invention provides a charging step of charging a latent image carrier with a charging member, a latent image forming step of forming a latent image on the latent image carrier using coherent light, and a process of forming a latent image on the latent image carrier using toner. A developing step of developing a toner image by developing an electrostatic latent image, and a transfer step of transferring the formed toner image onto a transfer material, wherein the toner comprises at least a binder resin and a colorant. Colored particles having a volume average particle size of 2.0 to 5.0 μm, colored particles of 1.0 μm or less being 20% by number or less, and colored particles of more than 5.0 μm. An image forming method, wherein the charging step is a step of charging the latent image carrier in a state where the charging member and the latent image carrier have a gap. It is.

The colored particles have a volume average particle size of 2.0 to 5.0.
μm, colored particles of not more than 1.0 μm are not more than 20% by number,
Colored particles exceeding 5.0 μm are 10% by number or less,
If the charging step is a step of charging the latent image carrier in a state where the charging member and the latent image carrier have a gap, the charging can be performed more uniformly, and high image quality can be obtained over a large number of sheets. Image can be obtained. Further, in order to charge the latent image carrier without contacting the charging member,
The latent image carrier is not contaminated, and no charging failure due to the contamination is caused.

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.
0% by number or less, colored particles exceeding 5.0 μm are suppressed to 10% by number or less, and in the charging step, the charging member and the latent image carrier have a gap.
This is a step of charging the latent image carrier.

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 and which is comparable 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 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.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a charging step of charging a latent image carrier with a charging member, a latent image forming step of forming a latent image on the latent image carrier using coherent light, and a latent image forming step using toner. An image forming method comprising: a developing step of developing an electrostatic latent image on an image carrier to obtain a toner image; and a transfer step of transferring the formed toner image onto a transfer material. It is composed of colored particles containing a resin and a coloring agent, and has a volume average particle size of 2.0 to
5.0 μm, colored particles of 1.0 μm or less are 20% by number or less, colored particles of more than 5.0 μm are 10% by number or less, and the charging step includes the charging member and the latent image carrier. Is a step of charging the latent image carrier in a state having a gap.

[Image Forming Method] The image forming method of the present invention comprises a charging step of charging a latent image carrier with a charging member, a latent image forming step of forming an electrostatic latent image on the 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.

The charging step is a step of charging the charging member without contacting the latent image carrier, and is a so-called non-contact charging method. As a non-contact charging method, for example,
A corona charging system described in JP-A-10-198125 may be used. Alternatively, a needle electrode device that generates a corona discharge by applying a high voltage to one needle electrode may be used.

Further, a plate-shaped solid electrode described in JP-A-10-31361 may be used. Examples of the material constituting the solid electrode include a π-conjugated system, a metal chelate system, a charge-transfer complex-based conductive polymer material, a conductive composition in which a conductive material is blended with a polymer, soda-lime glass,
And the like, additives, and ceramics. These plate-shaped solid electrodes are arranged close to each other so that a gap of 100 to 1000 μm is formed between the solid electrodes and the electrophotographic photosensitive member.

As an exposure light source for forming a latent image,
Coherent light (laser) is preferred. 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 preferably used. Further, a laser beam having a spot diameter of 50 μm or less, more preferably 30 μm or less, particularly 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.

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 binder resins for toners can be 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.

Examples of the (meth) acrylate monomer 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.

As the colorant contained in the colored particles, pigment particles are used. 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 as a colorant of a toner is equivalent to a circle by a melt flushing method. 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 size of the dispersed pigment particles in the binder resin is defined as the diameter of a part of the colored particles 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 size 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 preferably satisfies the following relational expression (1). 25 ≦ a · D · C ≦ 90 (1)

If the value of a · D · C (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 liable 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.

The coloring power varies 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)

Needless to say, even pigments of the same color have different coloring powers due to differences in chemical structural formulas and the like. Therefore, 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 preferred. 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 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 adhesive force between the colored particles or between the colored particles and the latent image carrier or the carrier, and preventing the developing property, the transfer property or the cleaning property from being lowered. 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 ultrafine particles improve the fluidity of the toner (colored particles), reduce the degree of agglomeration, and contribute to the improvement of environmental stability due to 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 a metatitanic acid and a silane compound, which is highly hydrophobic, hardly generates agglomerates due to no baking treatment, and has good dispersibility when externally added. 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 the two 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 latent image carrier and the carrier surface are contaminated with the external additives. 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 (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 Fa 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%.

If 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%.

If 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%.

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, 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 of 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, 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 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 has a value opposite to the positive or negative (that is, 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 the 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 formula (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.) Toner straight flight distance 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.

Accordingly, 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 directly sampled 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, an electrostatic latent image developer actually used consisting of a toner and a carrier is put into a glass bottle, and stirred for 2 minutes with a turbuler 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. Magnetic particles such as iron powder, ferrite, iron oxide powder, nickel, etc. 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 carrier preferably has a volume average particle diameter of 50 μm or less, 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 of 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, in the toner image of each color to be formed, it is preferable that the weight (TMA) of the toner per 1 cm ² 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, in a 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.

As the electrophotographic latent image carrier used in the exposure step of the present invention, any of those conventionally used as photoconductors can be used. Specific examples include an organic photoreceptor and an inorganic photoreceptor. Such a photoreceptor generally has a photosensitive layer formed on a conductive substrate. Examples of the conductive substrate include a metal plate using a metal or alloy such as aluminum, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium, gold, and platinum, a metal drum, a metal belt, or a conductive substrate. Paper, a plastic film, a belt, or the like, which is coated, vapor-deposited, or laminated with a conductive polymer, a conductive compound such as indium oxide, or a metal or alloy such as aluminum, palladium, or gold is used. Further, if necessary, the surface of the conductive substrate, various treatments within a range that does not affect the image quality, for example, anodic oxide film treatment of the surface, thermal hydroxylation treatment or chemical treatment, coloring treatment or graining etc. Those subjected to diffuse reflection processing or the like can also be used.

As the photosensitive layer in the present invention, a latent image carrier having a single-layer photosensitive layer or a latent image carrier having a laminated photosensitive layer can be used. 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. In the charge generation layer, as the charge generation substance, for example, azo pigments, quinone pigments, perylene pigments, indigo pigments,
Thioindigo pigments, bisbenzimidazole pigments,
Phthalocyanine pigments, quinacridone pigments, quinoline pigments, lake pigments, azo lake pigments, anthraquinone pigments, oxazine pigments, dioxazine pigments,
Various organic pigments such as triphenylmethane-based pigments, azurenium-based dyes, squarium-based dyes, pyrylium-based dyes, triallylmethane-based dyes, xanthene-based dyes, thiazine-based dyes, various dyes such as cyanine-based dyes, and more , Amorphous selenium, trigonal selenium, tellurium,
Inorganic materials such as selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc oxide, and zinc sulfide are used.
Of these, aromatic condensed ring pigments, perylene pigments, and azo pigments are preferred in terms of sensitivity, electrical stability, and photochemical stability to irradiation light. 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, etc. are used. But it is not limited thereto. 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.

The polymer charge transporting material may be formed alone, or may be formed by dispersing 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.

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 photo-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.

[0119]

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 parts by weight, Tg: 65 ° C.) and 75 parts by weight of a water-containing paste (40% by weight of pigment content) of a magenta pigment (CI Pigment Red 57: 1) are mixed in a kneader-type kneader and gradually heated. . 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 the magenta pigment was replaced with a water-containing paste (pigment blue 15: 3) (a pigment content of 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) Preparation 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 respective 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 50 parts by weight of the polyester resin and 50 parts by weight of the yellow flushing pigment were used instead of 25 parts by weight of the magenta 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 hydrophobization 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 is the value F obtained by the above-mentioned equation (2).
(%). 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.

[0130]

[Table 1]

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. 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 respective two-component developers obtained above, the following various evaluation tests were performed on the toner. 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. As a charging device, a corona discharge type charging device is used, and is charged to -400V.

<TMA> A solid image having an area ratio of 100% is prepared, 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 50 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.

<Granularity> Gradation images having image area ratios of 5% and 10% are prepared, and the obtained images are visually observed to evaluate highlight portion granularity. The specific evaluation criteria are as follows. A: 5% and 10% do not scatter. ×: Scattering is observed in both 5% and 10%.

<Evaluation of Image Quality> If no image defect has occurred after copying 5,000 sheets, the result is indicated by ○, and if any image defect occurs, the result is indicated by ×.

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

[0142]

[Table 2]

Further, when a full-color image was formed using the four-color two-component developer obtained in Examples 1 to 4, a high-quality image having excellent intermediate color development and no unevenness in density was obtained. Could be obtained repeatedly. On the other hand, using the two-color developer of four colors obtained in Comparative Examples 1 to 4,
When a full-color image was formed, the resulting image was inferior in color development of intermediate colors and low in sharpness.

[0144]

As described above, according to the image forming method or the image forming apparatus of the present invention, the latent image bearing member can be more uniformly charged by performing non-contact charging, so that a large number of sheets can be charged. High quality images can be obtained.
Further, since the latent image carrier is charged without contacting the charging member, the latent image carrier is not contaminated, and charging failure due to contamination is not caused.

[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

Claims (3)

[Claims] A charging step of charging the latent image carrier with a charging member; a latent image forming step of forming a latent image on the latent image carrier using coherent light; An image forming method comprising: a developing step of developing a toner image by developing an electrostatic latent image; and a transfer step of transferring the formed toner image onto a transfer material, wherein the toner comprises at least a binder resin and a colorant. Colored particles having a volume average particle size of 2.0 to 5.0 μm, colored particles of 1.0 μm or less being 20% by number or less, and colored particles of more than 5.0 μm. An image forming method, wherein the charging step is a step of charging the latent image carrier in a state where the charging member and the latent image carrier have a gap. . 2. The image forming method according to claim 1, wherein the toner has a charge amount of q (fC) and a toner particle size of d under an environment of a temperature of 20 ° C. and a humidity of 50%.
(Μm), wherein 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 in an image forming method. A charging unit for charging the latent image carrier with a charging member; a latent image forming unit for forming a latent image on the latent image carrier using coherent light; An image forming apparatus comprising: a developing unit that develops an electrostatic latent image to obtain a toner image; and a transfer unit that transfers the formed toner image onto a transfer material, wherein the toner includes at least a binder resin and a colorant. Colored particles having a volume average particle size of 2.0 to 5.0 μm, colored particles of 1.0 μm or less being 20% by number or less, and colored particles of more than 5.0 μm. An image forming apparatus, wherein the charging unit is a unit that charges the latent image carrier in a state where the charging member and the latent image carrier have a gap. .