JP2000267358A - Color toner, image forming method using same and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color toner which is excellent in flowability, does not cause the lowering of image density, surface stain and the contamination of the inside of a machine due to scattering, ensures good cleaning residual toners of the surface of a photoreceptor without chatter and the burr of a blade or the like and does not cause filming on the photoreceptor. SOLUTION: The color toner is used in an image forming method in which a residual toner on a photoreceptor is removed with a cleaning means brought into direct press contact with the photoreceptor and the photoreceptor is repeatedly used to form a color image. At least one color toner of the toner contains <=15% by number of toner particles having <=5 μm and <=5 vol.% toner particles whose diameter is >=2 times the weight average diameter of the toner, has the relation of 0.60<=D25/D75<=0.80 between the number average particle diameters D25 and D75 at which cumulative number distribution attains to 25% and 75% and has 6.0-11.5 μm weight average diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color toner for forming a color image by repeatedly using a photoreceptor to remove residual toner on the photoreceptor by a cleaning means for pressing the photoreceptor against the photoreceptor. The present invention relates to an image forming method used and an image forming apparatus.

[0002]

2. Description of the Related Art Electrophotography generally uses a photoconductive substance to form an electric latent image on a photoreceptor by various means, and then develops the latent image using toner. After transferring the powder image to paper or the like, the powder image is fixed by heating or solvent vapor to obtain a copy. Traditionally,
As disclosed in JP-B-61-147261, etc., the method of developing an electrostatic image using toner is roughly classified into a method using a so-called two-component developer in which a toner and a carrier are mixed. And a method using a one-component developer which is used alone without being mixed with a carrier.

[0003] Among them, a method using a two-component developer is as follows.
The toner and the carrier are agitated and rubbed to charge each other to have different polarities, and the electrostatic charge image having the opposite polarity is visualized (developed) by the charged toner. Depending on the type of the toner and the carrier, There are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method, and the like. As a toner applied to these various developing methods, fine powder in which a coloring agent such as carbon black is dispersed in a binder resin made of a natural resin or a synthetic resin is used. For example, particles obtained by finely pulverizing a dispersion of a colorant in a binder resin such as polystyrene to about 1 to 30 μm are used as toner. Further, those in which a magnetic material such as magnetite is further added to these components are used as a magnetic toner.

In recent years, in the field of copiers and printers, higher speeds and stabilization have always been desired due to market requirements.
In these high-speed copying machines or high-speed printers, a two-component developing system is mainly used. This is because the two-component toner is more likely to cause deterioration of the carrier and a change in the mixing ratio of the toner and the carrier than the one-component toner, and has a difficulty in maintenance and management of the apparatus and downsizing. Stable and good images can be obtained, and compared to one-component magnetic toner, do not contain a large amount of magnetic material, and as a result,
This is because the fixing property is particularly advantageous in a high-speed machine.

In the two-component developing system, a cleaning means for removing untransferred toner after transfer from the latent image carrier is provided by:
Generally, a blade or a fur brush is brought into direct contact with the latent image carrier, and at this time, the charge transport layer CTL on the back surface of the latent image carrier is worn due to direct contact with the cleaning member and the developing section. Will be. In particular, a high-speed machine requires abrasion resistance of a photoreceptor that can withstand a very large amount of copying and printing. For these reasons, for high-speed aircraft,
The mainstream is a combination of a flexible belt-shaped OPC photoconductor that can increase the effective use area of the photoconductor surface and brush cleaning that can perform relatively soft cleaning on the photoconductor. I have. However, even such a combination is not sufficient for a large number of copies exceeding one million, and higher durability is desired.

In recent years, there has been a strong demand for higher definition and higher resolution of copied images. However, the conventional two-component developer changes the particle size distribution of the toner particles in the developer due to the selective development of the toner particles when copying and printing a large number of copies for a long period of time, and as a result, the resolution of the image decreases. There is a problem to do.

On the other hand, such high definition. In order to obtain a high resolution image, Japanese Patent Application Laid-Open Nos.
JP-A-284158 and JP-A-7-295283 propose a developer in which the average particle size is small and the toner particle content is 5 μm or less and the distribution thereof is specified. Here, the toner particles of 5 μm or less are essential components for forming a high-definition, high-resolution image. It is said that an image with excellent reproducibility can be obtained without protruding from the latent image. In addition, the electric field intensity at the edge portion around the latent image is higher than that at the center portion, so that the toner particles adhere to the inside of the latent image less than the edge portion and the image becomes thinner. On the other hand, it is stated that this problem can be solved by defining the number% of toner particles having an intermediate particle size of 5 μm or more.

However, the smaller the particle size of the toner is, the more advantageous it is to form a high-definition and high-resolution image. As a typical example, as shown in FIGS. When it is contained, only 3% by volume of toner particles having a particle size of 5 μm or less is present in the volume distribution of the toner. It is difficult to imagine that the toner having the intermediate particle diameter is selectively deposited on the central portion of the latent image.

On the other hand, as shown in FIGS. 3 and 4, when the toner particles having a particle size of 5 μm or less are contained in a large amount of 60% by number, the fluidity is deteriorated and the inside of the apparatus due to the scattering of the toner is liable to occur. In particular, in a low-humidity environment, toner particles are liable to be overcharged, called charge-up, and the charged-up toner or fine powder adheres firmly to a carrier surface or a photoreceptor surface in a developer, resulting in a decrease in image density or This causes undesired problems such as generation of background stain, poor cleaning of the photoconductor such as chattering and blade turning, and occurrence of filming on the photoconductor.

Japanese Patent Application Laid-Open No. 4-1773 discloses that in order to solve the above-mentioned problem, the fluidity is improved by containing 0.1 to 5.0% by volume of 12.7 to 16.0 μm toner particles. However, it is certain that it is inferior to the case where the toner particles of 5 μm or less are reduced to 15% by number or less.

On the other hand, as a method of improving the fluidity, it is conceivable to increase the amount of the additive. However, it is considered that the fluidity is substantially the same when the additive is present on the surface of the toner particles. 5μ when 60% by number
In other words, 1.5 to 2 times the amount of the additive must be added to the toner of 17% by number or less. It is apparent that when such a large amount of additive is added, poor cleaning of the photoreceptor, occurrence of filming on the photoreceptor, deterioration of fixability, and the like are inevitable. In addition, when the amount of the additive is increased, toner dust tends to occur in a thin line portion called “transfer dust”. In particular, when a toner of two or more colors is overlapped and developed like a thin line portion of a color. The tendency becomes more pronounced.

Japanese Patent Application Laid-Open Nos. 4-124682 and 10-91000 disclose the effect of a one-component toner as a toner in which the number of toner particles having a particle size of 5 μm or less is specified to be small. The particle size distribution in a range where most of the toner particles that determine quality are present is not described, and it is not enough to obtain a high-resolution image.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide excellent fluidity, to prevent image density from being reduced, to prevent contamination in the apparatus due to background contamination and toner scattering, and to clean residual toner on the surface of a photoreceptor. An object of the present invention is to provide a color toner, an image forming method, and an image forming apparatus that do not cause photoreceptor cleaning defects such as chattering and blade turning or filming on the photoreceptor.

Another object of the present invention is to provide a color which does not generate toner dust in a thin line portion called "transfer dust", in which the durability of the photoreceptor and the cleaning blade is good, the fixing property is not deteriorated. An object of the present invention is to provide a toner, an image forming method, and an image forming apparatus.

Further, another object of the present invention is to provide an "insect-eating".
It is an object of the present invention to provide a color toner image forming method and an image forming apparatus which do not cause transfer failures such as missing during transfer of a thin line portion referred to as "fireflies" and white spots in a solid image due to uneven toner adhesion called "firefly".

[0016]

A feature of the present invention is that an image forming method for forming a color image by repeatedly using a photoreceptor to remove residual toner on the photoreceptor by cleaning means for directly contacting the photoreceptor. In the color toner used in the above, at least one color toner of 5 μm
The following toners are contained in an amount of 15% by number or less, the toner having a diameter twice or more the weight average diameter is contained in an amount of 5% by volume or less, and the number average particle diameters D25 and D7 in which the cumulative number distribution becomes 25% and 75%.
The above-mentioned object is attained by providing a color toner, wherein the relationship of (5) is 0.60 ≦ D25 / D75 ≦ 0.80 and the weight average diameter is 6.0 to 11.5 μm. I did it. Examples of the cleaning unit that directly presses the photoconductor include a cleaning unit that includes a cleaning blade that presses the photoconductor directly. The toner of the present invention solves the conventional problems, and is capable of withstanding strict requirements for high image quality and low-temperature fixing in recent high-speed image forming apparatuses, high durability of photoconductors, and the like.

The toner particles of the present invention have a particle size of 5 μm as described above.
The following particles are preferably 15% by number or less, more preferably 12% by number or less of the total number of particles. When the number of toner particles having a particle size of 5 μm or less is 15% by number or more, the fluidity is deteriorated, and the inside of the apparatus due to the scattering of the toner is liable to occur. In particular, in a low-humidity environment, the toner particles are liable to cause excessive charging called charge-up. The improved toner and fine powder adhere to the surface of the carrier and the surface of the photoreceptor firmly in the developer. As a result, the photoreceptor cleaning failure such as image density reduction, background contamination, bipiring, blade turning, etc. This causes undesirable problems such as occurrence of filming.

The toner having the above particle size distribution has improved fluidity and excellent fixability even when a small amount of an inorganic oxide is added.
Maintains high resolution and high-definition image quality even when copying and printing a large number of copies continuously, and also prevents photoreceptor cleaning defects such as chattering and blade turning when using recycled paper, and filling on the photoreceptor. It is possible to form an extremely stable image without causing problems such as trimming.

The reason that the toner of the present invention has the above-mentioned effects by having the above-mentioned particle size distribution is not necessarily clear, but is presumed as follows.
A toner particle having a size of 5 μm or less is difficult to control the charge amount, impairs the fluidity of the toner, causes a carrier contamination, a component which causes a cleaning failure and a problem of filming, and further, a toner scatter. As a result, it tends to become a component that stains the inside of the image forming apparatus.

When an inorganic oxide is added to further improve the fluidity, the smaller the particle size, the larger the surface area of the toner. It has been clarified that inorganic oxides must be added, which further causes problems such as filming and deterioration of fixability. That is, increasing the number of toner particles having a particle size of 5 μm or less cannot solve the above-mentioned problem and cannot be satisfactory when long-term use is considered. Therefore, in the toner of the present invention, by setting the toner particles having a particle size of 5 μm or less to 15% by number or less, the fluidity as a toner can be secured with a small fluidity improver, and the filming is substantially reduced and the fixing property is improved. Excellent toner is obtained.

Further, in the toner of the present invention, the number average particle diameters D25 and D25 at which the cumulative number distribution becomes 25% and 75%, respectively.
One feature is that the relationship of 75 is 0.60 ≦ D25 / D75 ≦ 0.80. D25 / 075
Indicates that the closer to 1, the sharper the particle size distribution. The sharpness of the particle size distribution of the toner that substantially forms the majority of the image means that the characteristics of each toner particle are equal, and the behavior of each toner in the developing unit is also the same. Therefore, the amount of toner selectively consumed and the amount of toner having different amounts of charge are reduced, and a high-definition, high-resolution image can be stably formed.

The relationship between the number average particle diameters D25 and D75 at which the cumulative number distribution under the sieve becomes 25% and 75% is D25 / D7
If 5 <0.60, the particle size distribution becomes broad, so that the behavior of each toner particle becomes non-uniform, so that selective consumption of toner and toner having a different charge amount cause deterioration of an image. When D25 / D75> 0.80, a sharp particle size distribution is obtained, which is advantageous for forming a high-resolution image. However, the productivity is extremely reduced in a conventional production method using dry pulverization and classification. .

In the toner of the present invention, the amount of toner particles having a diameter twice or more the weight average diameter is 5% by volume or less, more preferably 3% by volume or less, and the amount is preferably as small as possible. If the amount of toner particles having a diameter twice or more the weight average diameter exceeds 5% by volume, fine line reproducibility tends to be poor.

The weight average diameter of the toner of the present invention is 6.0 to I.
l. 5 μm, more preferably 7.0 to 9.0 μm
m. If the weight average diameter is less than 6.0 μm, problems such as contamination of the inside of the apparatus due to scattering of toner during long-term use, a decrease in image density in a low humidity environment, chattering, blade turning, and other poor cleaning of the photoconductor tend to occur. The weight average diameter is 1
When the thickness exceeds 1.5 μm, the resolution of a minute spot of 100 μm or less is not sufficient, and the image quality tends to be inferior due to scattered non-image portions.

The toner having the above-mentioned particle size distribution, which is a feature of the present invention, has a smaller specific surface area than the conventional toner. In this case, when used as a two-component developer by being mixed with a carrier, the number of times of contact between the toner particles and the carrier is reduced as compared with the conventional toner, and contamination of the carrier surface and abrasion / crushing of the toner particles are reduced. Less likely to occur. Furthermore, as the specific surface area is reduced, the amount of addition of the inorganic oxide can be reduced, and the photoreceptor cleaning failure such as chattering and blade turning by the inorganic oxide, filming on the photoreceptor, and further fixing failure are caused. Problems are less likely to occur. As a result, the life of the toner, the photoconductor, and the cleaning blade can be extended.

In general, when the pressure of the cleaning blade against the photoreceptor is high, the initial cleaning characteristics are good, but the friction coefficient between the photoreceptor and the blade increases in a high-temperature and high-humidity environment. A cleaning defect such as turning over of the blade may occur, or the load on the photoconductor may become excessive, causing phenomena such as scraping of the photoconductor and further stopping the rotation operation. But,
In a toner having a particle size distribution as a feature of the present invention,
Since the specific surface area of the toner is small, the content of the additive can be reduced, so that even if the pressing force of the cleaning blade to the photoconductor is set as low as 5 to 50 g / cm, the residual toner on the photoconductor is reduced. A good image can be obtained which can be removed satisfactorily and does not cause poor cleaning such as chattering and blade turning or filming on the photoreceptor, and also improves the durability of the photoreceptor and the cleaning blade.

Further, the toner particles in the range of D25 / D75 as described above, which is a feature of the present invention, exhibit further effects due to the presence of a small amount of inorganic oxide, and provide high-quality images stably for a long period of time. You can do it.

As the color toner of the present invention, it is preferable that at least one color toner satisfies the requirements of the above particle size distribution and further contains at least a binder resin, a colorant and at least two kinds of inorganic oxides. . Generally, as the particle size of the toner becomes smaller, its non-electrostatic adhesion becomes relatively large, and the fluidity deteriorates. Therefore, an inorganic oxide such as silica or titania is added to the toner as an additive to improve the fluidity. There is a need for improvement, and a remarkable effect can be obtained particularly by using an additive having a small particle size.

Further, when the content of the small particle additive is increased, the fluidity is further improved, but poor cleaning of the photoreceptor such as chattering and turning up of the blade and filming on the photoreceptor are liable to occur. Also, the durability of the cleaning blade deteriorates. Further, toner dust tends to occur in a thin line portion called “transfer dust”,
In particular, when two or more color toners are superposed and developed as in the case of a color thin line portion, the tendency becomes more remarkable.
On the other hand, by increasing the particle size of the additive, the fluidity is slightly reduced as compared with the additive having a small particle size, but a sufficient spacer effect is obtained, so that the adhesive force between the toner particles is attenuated. , “Insect biting”, “firefly” and the like, transfer defects are improved.

In the present invention, by using at least two kinds of inorganic oxides having different particle diameters as the above-mentioned inorganic oxide, characteristics such as fluidity and transferability can be satisfied at the same time. In particular, when two types of inorganic oxides having different particle sizes are used as additives, one type of inorganic oxide having an average primary particle size of 0.015 to 0.2 μm is added to the toner in an amount of 0.1 to 1.0. % By weight, and another inorganic oxide having another average primary particle diameter of 0.005 to 0.02 μm or less is added to the toner in an amount of 0.2 to 1.0% by weight. No transfer failures such as missing during transfer of thin line portions called "biting" and white spots on solid images due to unevenness of toner adhesion called "firefly" do not occur, and toner dust in thin line portions called "transfer dust" does not occur. High quality images free from blemishes can be obtained. At this time, the fixing performance is deteriorated, the photoconductor cleaning defects such as chattering and blade turnover, filming on the photoconductor, and the deterioration of the photoconductor and the cleaning blade are caused. I can't even see No.

The toner particle size distribution of the color toner of the present invention can be measured by various methods, but in the present invention, the measurement was performed using a Coulter counter. That is, a Coulter counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a PC 9801 personal computer (manufactured by NEC) were connected. A 1% NaCl aqueous solution is prepared using graded sodium chloride.

The measuring method is as follows.
In 150 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzenesulfonate, is added as a dispersant,
Further, 2 to 20 mg of a measurement sample is added, and a dispersion treatment is performed for about 1 to 3 minutes using an ultrasonic disperser. In a separate beaker, 100 to 200 ml of the aqueous electrolytic solution is added, and the sample dispersion is added to the beaker so as to have a predetermined concentration, and 100 μm is used as an aperture by the Coulter Counter TAII.
The particle size distribution of the particles of 2 to 40 μm is measured on the basis of the number using an aperture, the volume distribution and the number distribution of the particles of 2 to 40 μm are calculated, and the weight-average weight average particle diameter (D4: The median value of each channel is defined as a representative value of the channel).

In the present invention, when the original having a small image area is continuously copied, that is, even when the amount of the residual toner containing the inorganic oxide is small, good cleaning is always performed. The cleaning blade and the toner container removed by the blade are removed so that the residual toner having the inorganic oxide is always present in the uncleaned portion of the photoconductor and moderate spacer particles are always present at the edge of the cleaning blade. An apparatus having a configuration provided at the upper portion is more preferable.

As the inorganic oxide of the present invention, Si, Ti,
Al, Mg, Ca, Sr, Ba, In, Ga, Ni, M
n, W, Fe, Co, Zn, Cr, Mo, Cu, Ag,
Oxides such as V and Zr and composite oxides are exemplified. Among them, fine particles of silica, titania and alumina are preferably used. Further, it is effective to perform surface modification treatment with a hydrophobizing agent or the like. The following are typical examples of the hydrophobizing agent.

Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyl Trichlorosilane, chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane, 3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane,
Vinyltriethoxysilane, vinylmethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, dimethylvinylchlorosilane, octyltrichlorosilane, decyltrichlorosilane, Nonyltrichlorosilane, (4-t
-Propylphenyl) trichlorosilane, (4-t-butylphenyl) trichlorosilane, dibentyldichlorosilane, dihexyldichlorosilane, dioctyldichlorosilane, dinonyldichlorosilane, didecyldichlorosilane, didodecyldichloro Silane, dihexadecyldichlorosilane, (4-t-butylphenyl) octyldichlorosilane, dioctyldichlorosilane, didecenyldichlorosilane, dinonenyldichlorosilane, di-2-
Ethylhexyldichlorosilane, di-3,3-dimethylpentyldichlorosilane, trihexylchlorosilane,
Trioctylchlorosilane, tridecylchlorsilane,
Dioctylmethylchlorosilane, octyldimethylchlorosilane, (4-t-propylphenyl) diethylchlorosilane, isobutyltrimethoxysilane. Methyltrimethoxysilane, octyltrimethoxysilane, trimethoxy (3,3,3-trifluoropropyl) silane,
Hexamethyldisilazane, hexaethyldisilazane, diethyltetramethyldisilazane, hexaphenyldisilazane, hexatolyldisilazane and the like. In addition, titanate-based coupling agents and aluminum-based coupling agents can also be used.

In the toner of the present invention, other additives such as lubricant powders such as Teflon powder, zinc stearate powder and polyvinylidene fluoride powder; Abrasives such as silicon carbide powder and strontium titanate powder; or conductivity-imparting agents such as carbon black powder, zinc oxide powder, tin oxide powder, and the like; Can be used in small quantities.

As the resin for toner of the present invention, conventionally known resins can be widely used. For example, it is made of a vinyl resin, a polyester resin, or a polyol resin. Examples of the vinyl resin include styrene such as polystyrene, poly-P-chlorostyrene, and polyvinyltoluene, and a homopolymer of a substituted product thereof: styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-
Vinyl toluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, Styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl Ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid Copolymer, styrene Styrene copolymers such as maleic acid ester copolymer: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, and the like polyvinyl acetate.

The polyester resin is composed of a dihydric alcohol as shown in the following group A and a dibasic acid salt as shown in the group B. May be added as the third component. Group A: ethylene glycol, triethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated Bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,2) -2,
2′-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,
0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -2,2′-bis (4-hydroxyphenyl) propane and the like. Group B: maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid,
Linoleic acid or esters of these acid anhydrides or lower alcohols. Group C: trivalent or higher alcohols such as glycerin, trimethylolpropane, and pentaerythritol; and trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid.

Examples of the polyol resin include an alkylene oxide adduct of an epoxy resin and a dihydric phenol, or a compound having one active hydrogen in the molecule that reacts with the glycidyl ether and the epoxy group, and an active hydrogen that reacts with the epoxy resin. Examples include those obtained by reacting two or more compounds in a molecule. In addition, the following resins can be mixed and used as needed. Epoxy resin, polyamide resin, urethane resin, phenol resin,
Butyral resin, rosin, modified rosin, terpene resin, etc. A typical example of the epoxy resin is a polycondensate of a bisphenol such as bisphenol A or bisphenol F with epichlorohydrin.

The following colorants are used in the present invention. Black colorants include carbon black, oil furnace black, channel black,
Examples include azine dyes such as lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides. Examples of the yellow colorant include cadmium yellow, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanza yellow G, Hanza yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake and the like. No. Examples of the orange colorant include molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.

Red colorants include red iron, cadmium red, permanent red 4R, lithol red,
Vilasolone Red, Watching Red Calcium Salt,
Lake Red D, Brilliant Carmine 6B, Quinacridone, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B. Examples of the purple coloring agent include Fast Violet B and Methyl Violet Lake. As a blue colorant,
Cobalt blue, Alli blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, Fast Sky Blue, and Indanthrene Blue BC.
Examples of the green colorant include chrome green, chromium oxide, pigment green B, and malachite green lake. These can be used alone or in combination of two or more.

Further, a release agent can be internally added to the toner of the present invention in order to prevent offset during fixing. Release agents include natural waxes such as candelilla wax, carnauba wax and rice wax, montan wax, paraffin wax, sasol wax, low molecular weight polyethylene, low molecular weight polypropylene,
Examples include alkyl phosphate esters. These are selected depending on the binder resin and the surface material of the fixing roller.

The melting point of these template agents is preferably from 65 to 90 ° C. When the temperature is lower than this range, blocking during storage of the toner tends to occur. When the temperature is higher than this range, the offset may easily occur in a region where the fixing roller temperature is low.

In the toner of the present invention, it is preferable to use a charge control agent mixed (internally added) with toner particles or mixed (externally added) with toner particles. The charge control agent makes it possible to control the amount of charge optimally according to the developing system. In particular, in the present invention, it is possible to further stabilize the balance between the particle size distribution and the amount of charge. Nigrosine, quaternary ammonium salts, imidazole metal complexes or salts can be used alone or in combination of two or more to control the toner to be positively charged. In addition, a salicylic acid metal complex or salt, an organic boron salt, a calixarene-based compound, or the like is used to control the toner to be negatively charged.

As an example of the method for producing the toner of the present invention, first, the above-mentioned binder resin, pigment or dye as a colorant, a charge controlling agent, a lubricant, other additives, and the like are mixed with a Henschel mixer. After mixing thoroughly with a mixer,
A batch type twin roll, a Banbury mixer or a continuous type twin screw extruder such as a KTK type twin screw extruder manufactured by Kobe Steel, a TEM type twin screw extruder manufactured by Toshiba Machine Co., a twin screw extruder manufactured by KCK, The constituent materials are formed by using a PCM type twin screw extruder manufactured by Ikegai Iron Works, a KEX type twin screw extruder manufactured by Kurimoto Tekkosho, or a hot kneader such as a continuous single screw kneader such as a bus kneader. Knead well, cool, then coarsely pulverize using a hammer mill, etc., further pulverize with a fine pulverizer using a jet stream or a mechanical pulverizer, and classify using a swirl stream or classify using the Coanda effect. Classify to a predetermined particle size with a machine. Then, the inorganic oxide and the toner are sufficiently mixed by a mixer such as a Henschel mixer.
Pass through a sieve of 50 mesh or more to remove coarse particles and aggregated particles.

When the toner of the present invention is used as a two-component developer, it is used by mixing with a carrier. As the carrier that can be used in the present invention, for example, iron powder, ferrite powder, powder having magnetic properties such as nickel powder, glass beads, and the like, all known ones can be used.
It is preferable to cover these surfaces with a resin or the like. In this case, the resin used is polyfluorocarbon, polyvinyl chloride, polyvinylidene chloride, phenol resin, polyvinyl acetal, acrylic resin, silicone resin and the like. As a method of forming the resin layer, a resin may be applied to the surface of the carrier by a spraying method, a dipping method, or the like, as in the related art. Here, the average particle size of these carriers is usually 10 to 10.
It is 100 μm, preferably 30 to 50 μm. In addition,
The amount of the resin used is usually 1 to 10% by weight based on 100 parts by weight of the carrier. Further, the mixing ratio of the toner and the carrier is generally about 0.5 to 6.0 parts by weight of the toner per 100 parts by weight of the carrier.

Hereinafter, the present invention will be described specifically with reference to examples. However, the present invention is not limited to these examples. In addition, the part in an Example represents a weight part.

[0048]

[Example] Classified toner formulation <Yellow classified toner> Binder resin Polyol resin 100 parts Coloring agent Disazo yellow pigment (C.1. Pigment Yellow 180) 8 parts Charge control agent Zinc salicylate derivative 2 parts <Magenta classified toner> 2. Coloring resin Polyol resin 100 parts Coloring agent Quinacridone-based magenta pigment (CI. Pigment Red 122) 8 parts Charge control agent Zinc salicylate derivative 2 parts <Cyan classified toner> Binder resin polyol resin 100 parts Coloring agent Steel phthalocyanine blue pigment 5 parts (CI Pigment Blue 15: 3) Charge control agent Zinc salicylate derivative 2 parts <Black classified toner> Binder resin Polyol resin 100 parts Colorant carbon black 6 parts Charge control agent Zinc salicylate derivative 2 parts

Production Examples 1-5 of Classified Toners Classified toners were produced according to the following procedure. 1. 2. Mixing each raw material of the above-mentioned classified toner formulation with a Henschel mixer for each color 2. Melt kneading with a twin screw extruder set at 130 ° C. 3. Cool the mixed wire and coarsely crush it with a cutter mill. 4. Pulverization by a fine pulverizer using a jet stream 6. Classify using a revolving air classifier 6. Remove coarse particles and agglomerated particles with a 250-mesh sieve Here, by changing the pulverization and classification conditions of the above 4,5, each classified toner having a different particle size distribution is obtained. Obtained. The particle size distributions of Production Examples 1 to 5 obtained at this time are shown in Table 1 for a cyan classified toner as an example. For the classified toners of yellow, magenta and black, a particle size distribution almost corresponding to the classified toner of cyan in each of the production examples was obtained.

[0050]

[Table 1]

Example 1 To a yellow, magenta, cyan, and black classified toner of Production Example 1, 1.0% by weight of silica having a volume average particle diameter of 0.2 μm, surface-treated with hexamethyldisilazane, was added, and a Henschel mixer was added. (Made by Mitsui Miike Co., Ltd.) to obtain the color toner of the present invention.

Examples 2 to 12 and Comparative Examples 1 to 4 Color toners were obtained in the same manner as in Example 1 by using a Henschel mixer (manufactured by Mitsui Miike Co.) for mixing the inorganic oxide. Table 2 shows production examples of the classified toners used at this time, types and particle sizes of inorganic oxides, addition amounts, and the like.

[0053]

[Table 2]

Evaluation <Manufacture of carrier> Particle size 4 in fluidized bed type coating apparatus
While 5 kg of 5 μm Cu-Zn ferrite is put and fluidized, the silicone resin liquid (SR-2411, solid content 2
0% by weight, manufactured by Toray Dow Corning Silicone Co., Ltd.) 50
A solution consisting of 0 g and toluene (1450 g) was sprayed under heating at 80 ° C., and further baked at 210 ° C. for 2 hours to obtain a carrier coated with a silicone resin.

<Production of full-color developer> Five parts of each of the yellow, magenta, cyan, and black toners of Examples and Comparative Examples and 95 parts of a carrier were mixed for 10 minutes using a turbuler shaker mixer to obtain a color having a toner concentration of 5%. Each developer was obtained. The color toners and developers of these examples and comparative examples were evaluated as follows.

Evaluation 1: Evaluation of fluidity The fluidity was evaluated by measuring the degree of aggregation of each toner by the following method. Using a powder tester (manufactured by Hosokawa Micron Co., Ltd.), sieves having openings of 150 μm, 75 μm, and 45 μm are arranged in this order from the top, and a sieve having an opening of 150
2 g of each toner is put into a sieve of μm, and 3
Vibration was applied for 0 second, the toner weight on each sieve after the vibration was measured, weighted 0.5, 0.3, and 0.1 respectively, added, and calculated as a percentage. Here, it is shown that the smaller the obtained value is, the better the fluidity of the toner is.
Table 3 shows the aggregation degree of each toner obtained at this time.

Next, 400 g of each of the above color developers was
As shown in FIG. 5, a cleaning blade and a toner container for collecting the removed toner are installed on the photoreceptor, and a cleaning device in which the pressure of the cleaning blade against the photoreceptor is 30 g / cm is provided. It was set in a copying machine (PRETER550, manufactured by Ricoh Co., Ltd.), and 10,000 copies were continuously copied, and the following various evaluations were made. Table 3 shows the evaluation results at this time. here,
In Table 3, ○, △, and × indicate the three-level evaluation of each evaluation item, ○ indicates a very good level, △ indicates a level having no practical problem, and × indicates a level having a practical problem. Is shown.

Evaluation 2: Image Density The image density of the solid portion after continuous copying was measured by X-Rite 938, and the difference from the image density of the same portion in the initial image was evaluated in three steps. Evaluation 3: Background Stain The background stain was evaluated by visually observing the degree of background stain in the non-image area during continuous copying in three stages. Evaluation 4: Toner Scattering Toner scattering was evaluated by visual evaluation of the degree of toner contamination in the copying machine after continuous copying. Evaluation 5: Cleaning Property The cleaning property was evaluated by visually evaluating the degree of the amount of toner remaining in a portion corresponding to the solid portion on the photoreceptor after continuous copying. Evaluation 6: Filming In the evaluation of filming, the degree of filming on the photoreceptor after continuous copying was visually evaluated in three stages. Evaluation 7: Fixability The fixability was evaluated by fixing a solid image at the center temperature of a designated fixing temperature of a full-color copying machine during continuous copying, and applying a load of 50 g with a drawing tester manufactured by Ueshimasha Co., Ltd. Was scratched, and the degree of the scratch was visually evaluated in three stages. Evaluation 8: Transfer Chile The transfer chile was evaluated by using a microscope VH-5910 (manufactured by KEYENCE CORPORATION) equipped with a 200 × lens (VH-200) when a 1-dot blue line was output during continuous copying. Observation was made, and the degree of dust in one line in the visual field was evaluated in three steps. Evaluation 9: Durability The durability of the photosensitive member and the cleaning blade was evaluated. The durability of the photoreceptor was evaluated by visually evaluating the degree of white streaks generated on the image after continuous copying in three stages. Here, the lower the degree of occurrence of white streaks, the higher the durability of the photoconductor. The durability of the cleaning blade was evaluated by visual evaluation in three stages by comparing the degree of damage of the cleaning blade after continuous copying with that of an unused blade.

Evaluation 10: Insect Eating Insect eating was evaluated by a microscope VH-5910 (Keyence Corporation) equipped with a multiplied lens (VH-200) by a factor of 200 when outputting a 1-dot black line during continuous copying. Manufactured), and the degree of insect biting of one line in the visual field was visually evaluated in three stages. Evaluation 11: Firefly Fireflies were evaluated in three stages by visual observation of the occurrence of fireflies in a solid image portion during continuous copying.

[0060]

[Table 3]

[0061]

The color toner, the image forming method and the image forming apparatus of the present invention have excellent fluidity and do not cause a decrease in image density, contamination in the machine due to background contamination or toner scattering, and the like.
Also, when cleaning the residual toner on the photoreceptor surface,
No poor cleaning of the photoreceptor such as chatter and turning over of the blade, and no occurrence of filming on the photoreceptor were observed. Further, according to the color toner, the image forming method and the image forming apparatus of the present invention, the durability of the photoreceptor and the cleaning blade is good, the fixing property is not deteriorated, and the toner in the fine line portion called “transfer dust” is further improved. Chile did not occur. Further, according to the color toner, the image forming method and the image forming apparatus of the present invention, during transfer of a pongee line called “insect eating” or white spots in a solid image due to uneven adhesion of toner called “firefly”, etc. A high quality image without transfer failure was obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a typical number particle size distribution when 17% by number of particles of 5 μm or less are present.

FIG. 2 is a diagram showing a typical volume particle size distribution when 17% by number of particles of 5 μm or less are present.

FIG. 3 is a view showing a typical number particle size distribution when particles of 5 μm or less are 60% by number.

FIG. 4 is a diagram showing a typical volume particle size distribution when particles having a particle size of 5 μm or less are 60% by number.

FIG. 5 is a sectional view of a full-color copying machine used in Examples and Comparative Examples.

[Explanation of symbols]

 Reference Signs List 101 Scanner 112 Printer 201 Copier 202 Black developing unit 203 Cyan developing unit 204 Magenta developing unit 205 Yellow developing unit 206 Intermediate transfer belt 207 Charging device 208 Laser optical system 209 Contact glass 210 Exposure lamp (halogen lamp) 211 Reflection mirror 212 Image formation Lens 213 CCD image sensor 214 Cleaning device 215 Photoconductor 216 Paper feed unit 217 Transfer bias roller 218 Conveying belt 219 Fixing device 220 Paper discharge tray 221 Bias roller 222 Belt cleaning device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenichi Uehara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yoshihiro Sugiyama 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Tomio Kondo 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Yasutaka Iwamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company ( 72) Inventor Yasushi Nakamura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Ryoichi Ito 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yasuyuki Sanui 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H005 AA08 AA21 CA21 CA26 CB07 CB13 DA05 DA07 EA05 EA07

Claims (6)

[Claims] 1. A color toner used in an image forming method of forming a color image by repeatedly removing a residual toner on a photoreceptor by a cleaning unit for directly pressing the photoreceptor, and using the photoreceptor repeatedly. 1
The number-average particle diameter of the toner of the color contains 15% by number or less of toner of 5 μm or less, the toner of 2% or more of the weight average diameter by 5% by volume or less, and the cumulative number distribution is 25% and 75%. The relation between D25 and D75 is 0.60 ≦ D25 / D
75 ≦ 0.80, and the weight average diameter is 6.0 to 11.5
μm. 2. The color toner according to claim 1, wherein the at least one color toner contains at least a binder resin, a colorant, and two or more inorganic oxides. 3. Two kinds of inorganic oxides (A and B respectively)
The oxide A has an average primary particle diameter of 0.0
15 to 0.2 μm, and the amount added is 0.1 to 1.
The color toner according to claim 2, which is 0% by weight. 4. The oxide B has an average primary particle diameter of 0.005.
0.02 μm, the amount added is 0.2 to 1.0 with respect to the toner.
The color toner according to any one of claims 2 to 3, wherein the color toner is% by weight. 5. An image forming method according to claim 1, wherein a residual toner on the photosensitive member is removed by a cleaning means for directly pressing the photosensitive member, and a color image is formed by repeatedly using the photosensitive member. An image forming method, comprising using the color toner described in (1). 6. An image forming apparatus, comprising: a cleaning unit that presses against a photoconductor, removes residual toner on the photoconductor, and forms a color image by repeatedly using the photoconductor. And a toner container for storing the toner removed by the cleaning blade is disposed above the photosensitive member.