JP3492169B2 - Image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chromatic color toner for developing an electrostatic image and an image forming method.

[0002]

2. Description of the Related Art Conventionally, a large number of electrophotographic methods are known, but generally, a surface of a latent image carrier made of a photoconductive material is formed by corona charging or direct charging by a charging roller. After being charged in the same manner, an electrical latent image is formed on the latent image bearing member by irradiation with light energy, and then the latent image is developed with a positively or negatively charged toner to form a visible image. After the toner image is transferred onto a transfer material such as paper, if necessary, the toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy. Then, the toner left untransferred on the transfer material at the time of transfer is cleaned by various methods, and the above steps are repeated.

As a method of visualizing an electric latent image with toner, there are known a cascade developing method, a magnetic brush developing method used by mixing with a carrier, a non-magnetic one-component developing method, a pressure developing method and the like. . Further, there is also used a magnetic one-component developing method in which a magnetic toner is used and a rotating sleeve having a magnetic pole in the center is used to fly by an electric field between the photosensitive member and the sleeve. The toner used in either case is used by being charged by frictional charging with a charging member such as a sleeve or a carrier.

In recent years, in image forming apparatuses by electrophotography, such as printers and copiers, the resolution of technology has become higher and higher resolution is also required in the developing system. Is coming. Further, in the copying machine, the function is advanced, and therefore, like the printer, it is in the direction of digitization. In this direction, the method of forming an electrostatic charge image by a laser is mainly used, and therefore, it is also advancing toward high resolution, and here also, as in the case of a printer, a high resolution / high definition developing method is required. .

Particularly, in recent years, with the widespread use of electrophotographic color image forming apparatuses, their applications have been widespread and varied.
The demands on the image quality are becoming severe. When copying images such as general photographs, catalogs, and maps, even the finest parts are not crushed or interrupted,
It is required to reproduce extremely finely and faithfully.

In an electrophotographic image forming apparatus using a recent digital image signal, a latent image is formed by gathering dots having a constant potential on the surface of a latent image carrier, a so-called photoconductor, to form a solid image. The part, the halftone part, and the line part are expressed by changing the dot density. However, with this method, it is difficult for the toner particles to adhere to the dots faithfully, and the toner particles protrude from the dots,
The problem that the gradation of the toner image corresponding to the ratio of the black and white dot densities of the digital latent image cannot be obtained easily occurs. Furthermore, in order to improve the image quality, if the dot size is reduced to improve the resolution, the reproducibility of the latent image formed from minute dots becomes more difficult, and the resolution and especially the gradation of the highlight part The image tends to be poor in sharpness and lack in sharpness.

Further, although the image quality is good in the initial stage, the image quality may deteriorate during the copying or printout. It is considered that this phenomenon occurs because only toner particles that are easily developed are first consumed while copying or printing is continued, and toner particles having poor developability accumulate and remain in the developing machine. Further, the accumulated toner may impede normal frictional electrification between the newly replenished toner and the charging member, causing stains on the non-image portion, so-called fog.

Up to now, several developers have been proposed for the purpose of improving the image quality. JP-A-5
Japanese Patent Laid-Open No. 1-3244 proposes a non-magnetic toner intended to improve the image quality by regulating the particle size distribution. Among the toners, the toner having a particle size of 8 to 12 μm is mainly used, and it is relatively coarse. According to the study of the present inventors, it is difficult for the toner to have a uniform “paste” on the latent image. Further, from the characteristic that 5 μm or less is 30 number% or less and 20 μm or more is 5 number% or less, the point that the particle size distribution is broad also tends to deteriorate the uniformity.
In order to form a clear image using the toner having such coarse toner particles and having a broad particle size distribution, the toner particles are thickly stacked to fill the gaps between the toner particles to form an apparent image. It is necessary to increase the concentration,
There is also a problem that the amount of toner consumption required to obtain a predetermined image density increases.

Japanese Unexamined Patent Publication (Kokai) No. 54-72054 proposes a non-magnetic toner having a sharper distribution than the former, but the size of particles having an intermediate weight is 8.5 to 11.0.
There is still room for improvement as a high-resolution color toner that is as rough as μm and faithfully reproduces a minute dot latent image.

Japanese Unexamined Patent Publication (Kokai) No. 58-129437 proposes a non-magnetic toner having an average particle size of 6 to 10 μm and a maximum number of particles of 5 to 8 μm, but particles of 5 μm or less are 15% by number or less. There is a tendency that an image lacking sharpness is formed.

According to the studies made by the present inventors, toner particles of 5 μm or less clearly reproduce minute dots of a latent image and have a main function of dense toner paste on the entire latent image. It was discovered. In particular, in the electrostatic latent image on the photoconductor, electric field lines are concentrated, so that the electric field strength is higher at the edge portion which is the contour than inside, and the sharpness of the image quality is determined by the quality of the toner particles gathered at this portion. According to the study by the present inventors, it has been found that the amount of particles of 5 μm or less is effective for solving the problem of highlight gradation.

However, in general, the smaller the particle size of the toner particles, the stronger the adhesion force (image force, van der Waals force, etc.) to the sleeve, the carrier or the surface of the photoconductor, and it becomes difficult to develop or transfer the toner particles. Are known.

When a large number of images are output using such a toner containing a large amount of toner, the toner having poor developability is accumulated on the sleeve or the carrier, which causes deterioration of image quality as described above. .

Further, when the toner image formed on the photosensitive member in the developing process is transferred to the transfer material in the transferring process and the transfer residual toner remains on the photosensitive member as described above, it is cleaned in the cleaning process. , Need to be stored in the waste toner container. Regarding this cleaning process, conventional blade cleaning, fur brush cleaning,
Although roller cleaning and the like have been used, either method mechanically scrapes off the transfer residual toner, or dams it and collects it in a waste toner container,
There has been a problem caused by such a member being pressed against the surface of the photoconductor. For example, it is possible to shorten the life of the photoconductor by abrading the photoconductor by strongly pressing the member, or because the toner is strongly rubbed on the surface of the photoconductor so that the toner is fused to the photoconductor. From the viewpoint of the apparatus, the size of the apparatus is inevitably increased due to the provision of such a cleaning apparatus, which has been a bottleneck when aiming to make the apparatus compact.

Further, from the viewpoint of ecology, a system without waste toner is desired in the sense of effectively utilizing the toner.

In response to these demands, according to the above description, by finely managing the particle size distribution of the toner, high resolution, high durability, downsizing of the apparatus, and further ecological characteristics are simultaneously achieved. It could be achieved.

However, as described above, the currently controlled particle size is on the order of micron, and the content of the toner having a particle size of less than 1 μm has not been managed yet.

A technique called simultaneous development cleaning or cleanerless is disclosed in Japanese Laid-Open Patent Publication No. 5-2287, which focuses on a positive memory, a negative memory and the like due to the influence of transfer residual toner on an image. is there.
However, with the increasing use of electrophotography, it is necessary to transfer toner images to various transfer materials.
In this sense, it is not satisfactory for various transfer materials.

Those which disclose the technology relating to the cleanerless are disclosed in JP-A-59-133573, JP-A-62-203182, and JP-A-63-133179.
Japanese Patent Laid-Open No. 64-20587, Japanese Patent Laid-Open No. 2-3
There are JP-A No. 02772, JP-A No. 5-2289, JP-A No. 5-53482, JP-A No. 5-61383, etc., but no mention is made of a desirable toner structure.

Further, in the simultaneous developing cleaning which essentially does not have a cleaning device, in order to collect the transfer residual toner in the non-image area at the time of development, it is essential to rub the surface of the photosensitive member with the toner and the toner carrier. For this reason, toner deterioration due to long-term use, toner carrier surface deterioration, photoconductor surface deterioration, wear, etc. are caused, and deterioration of durability characteristics remains a problem, and the conventional technology does not sufficiently solve the problem and developability is deteriorated. Both durability characteristics were desired.

Further, in the cleanerless structure,
When the transfer residual toner increases, the charging member is contaminated and it becomes difficult to uniformly charge the surface of the latent image carrier.
Since so-called charging failure occurs, an image failure will appear during development.

This development is a problem that also occurs in an electrophotographic process essentially having a cleaning step. That is, if the amount of transfer residual toner becomes too large to be removed by the cleaning member, the toner reaches the charging portion after passing through the cleaning portion and contaminates the charging member, so that the image defect also occurs.

Incidentally, in Japanese Patent Laid-Open No. 3-259161,
A non-magnetic one-component developer having a specified shape factor, specific surface area and particle size has been proposed, but the developer specified in the publication has insufficient durability.

Japanese Patent Application Laid-Open No. 61-279864 proposes a toner in which the shape factors SF1 and SF2 are specified. However, there is no description regarding transfer in this publication, and as a result of carrying out Examples, transfer efficiency is low and further improvement is required.

Further, Japanese Patent Application Laid-Open No. 63-235953 proposes a magnetic toner spherically formed by a mechanical impact force. However, the transfer efficiency is still insufficient and further improvement is needed.

On the other hand, a toner by the suspension polymerization method has also been proposed for a long time (for example, Japanese Patent Publication No. 36-10231). In this suspension polymerization method, a polymerizable monomer and a colorant (and optionally a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly dissolved or dispersed to form a monomer composition. After that, this monomer composition is dispersed in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer, and a polymerization reaction is simultaneously carried out to obtain toner particles having a desired particle size. Is what you get. The toner obtained by this suspension polymerization method has high transferability because the individual toner shapes are substantially spherical and the distribution of the charge amount is relatively uniform.

In the toner having such a uniform shape,
By subtly managing the content of particles with a particle size of less than 1 μm, the achievement of an electrophotographic image forming apparatus that can satisfy all of the above-mentioned high resolution, high durability, downsizing of the apparatus, and ecology. The possibility of is expected.

[0028]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chromatic color toner for developing an electrostatic image and an image forming method which can solve the above-mentioned problems of the prior art.

That is, one of the objects of the present invention is a chromatic color for developing an electrostatic charge image which is excellent in developability and has excellent durability capable of maintaining a high resolution image even when a large number of copied images or printer images are output. To provide a toner and an image forming method.

Further, an object of the present invention is that the transferability is excellent, the transfer residual toner is small, and the cleaning device is not provided.
It is an object of the present invention to provide a chromatic color toner for developing an electrostatic charge image and an image forming method capable of obtaining a stable image for a long period of time without causing a charging failure.

[0031]

[0032]

Means and operation for solving the problems] The present invention, strip the latent image holding member having a cylindrical shape for holding the electrostatic latent image
A charging step for abutting against the electric roller to perform primary charging, an electrostatic latent image forming step for forming an electrostatic latent image on the primary charged latent image holding member, and the developing device has the electrostatic latent image. A developing step by a one-component contact developing method for developing with a chromatic color toner to form a chromatic color toner image on the latent image carrier, and a recording material for the chromatic color toner image formed on the latent image carrier. in the transfer step, and an image forming method having a fixing step of fixing the chromatic color toner image transferred to the recording material to the recording material to be transferred to, developing device, the
Circle for carrying chromatic color toner and transporting it to the development area
It has a cylindrical toner carrier and holds the latent image.
Length in the direction of rotation at the contact area between the body and the toner carrier
Is 0.2 to 8.0 mm, and the chromatic color toner has chromatic color toner particles containing at least a binder resin, a colorant and a release agent, and the chromatic color toner particles Has a shape factor SF-2 of 100 to 140.
The chromatic color toner has a toner concentration of 1 g in the transmitted light spectrum when dispersed in an aqueous solution.
The ratio (A / B) of the absorbance A at a wavelength of 260 nm when converted to liters / liter and the absorbance B at a wavelength of 400 nm when converted to a toner concentration of 1 g / liter is 0.85 to 1.00. The colored toner is a toner produced by a polymerization method, and relates to an image forming method.

As described above, the control particle size of the toner in this technical field is on the order of microns, and the content of the toner having a particle size of less than 1 μm has not been managed yet.

However, as a result of diligent studies by the present inventors, it became clear that the presence of particles of less than 1 μm in the toner greatly affects the developability, durability and transferability of the toner, and the particle size distribution of the toner is It has been clarified that satisfying various characteristics can be obtained by delicate management, and further compactness of the device and ecological properties can be achieved.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION One of the features of the toner of the present invention is that
In the transmitted light spectrum in a state of being dispersed in an aqueous solution, the ratio of the absorbances at wavelengths of 260 nm and 400 nm is within a specific range.

Generally, the interaction between light and fine particles dispersed in a solution is mainly absorption and particle scattering.

In the case of fine particles of less than 1 μm, particle scattering occurs with respect to incident light having a short wavelength, especially 400 nm or less, and the transmitted light intensity decreases, and the degree of decrease correlates with the concentration of the fine particles. .

Therefore, it is possible to control the distribution number of particles of less than 1 μm in the toner based on the apparent absorbance in this wavelength range.

According to the study by the present inventors, as a standard for controlling the particle size distribution, in the transmitted light spectrum in a state of being dispersed in an aqueous solution, the wavelength at 260 nm and 400 nm when the toner concentration is converted into 1 g / liter. When the absorbances are A and B, A and B satisfy the following expressions, so that it becomes possible to greatly improve various toner characteristics.

0.85 ≦ A / B ≦ 1.00 further, 0.90 ≦ A / B ≦ 1.00 By so doing, various toner characteristics are further improved.

When A / B <0.85, it means that the number of particles of 1 μm or less in the toner is small,
Even if such a toner is used, it is difficult to obtain a high-resolution image, and the effect of a fine particle acting as a spacer as a transfer aid is small, so that high transferability cannot be obtained.

On the other hand, when 1.00 <A / B, it means that the number of particles of 1 μm or less in the toner is too large, which lowers the developing property and the transfer property and causes the deterioration of the image quality. In addition, in the cleanerless configuration, the charging property is adversely affected and the durability is reduced.

As a method of controlling the particle size distribution of the toner, there is a method of treating the toner with hot air. Specifically, a method of supplying toner into the circulating hot air flow to process the toner, a method of ejecting the toner with compressed air and radiating hot air thereto to perform the treatment, and the like can be mentioned. For example, it is possible to control the particle size distribution of toner to some extent by using the air classification method that is generally used, but if toner particles are present in agglomerated form, it is not possible to completely adjust the particle size distribution. difficult. In particular, fine particles of 1 μm or less have a strong cohesive property, and it is very difficult to control the content.

On the other hand, in the above-mentioned heat treatment method, the fine particles existing in agglomeration form one particle due to thermal energy, so that the particle size distribution can be adjusted relatively easily.

At this time, the content of fine particles of 1 μm or less can be controlled by controlling the residence time of the toner in hot air, the temperature of hot air, or the flow rate of hot air. The temperature is preferably not lower than the softening point of the toner and not higher than 300 ° C. At a temperature below the softening point, it is difficult to modify the aggregate of toner particles into a single particle, and at a temperature above 300 ° C, surface degradation of the toner such as decomposition of the material occurs even if the residence time in hot air is shortened. Is difficult to suppress and adversely affects the charging characteristics, which is not preferable.

Further, when the color toner is yellow toner, it is in the wavelength region of 400 nm or more and less than 500 nm, and when it is magenta color toner, it is 500 nm or more and 600 nm.
Wavelength range below 6 and 6 for cyan color toner
Since each has an absorption peak in the wavelength region of 00 nm or more and less than 800 nm, the transparency and tint of the OHP original becomes good when used as a color toner.

The color toner particles of the color toner of the present invention have a shape factor S measured by a toner image analyzer.
The value of F-2 satisfies the following formula, which further improves the transferability.

100 <SF-2 ≦ 140 Preferably 100 <SF-2 ≦ 130 And 100 <SF-2 ≦ 120 Is more preferable.

Further, the durability of the color toner particles is further improved when the value of the shape factor SF-1 measured by an image analyzer of the toner particles satisfies the following formula.

100 <SF-1 ≦ 140 Preferably 100 <SF-1 ≦ 130 And 100 <SF-1 ≦ 120 Is more preferable.

Here, in the present invention, SF-1 and SF-2 indicating the shape factor are, for example, FE-S manufactured by Hitachi Ltd.
2 μm magnified 1000 times using EM (S-800)
100 toner particle images described above were randomly sampled, and the image information was introduced into an image analysis device (LuzexIII) manufactured by Nicolet Co., for example, through an interface and analyzed, and the value obtained by the following equation was calculated. Shape factor SF
-1, SF-2.

[0052]

[Equation 1] (Where MXLNG is the absolute maximum length of the particle, PERI is the perimeter of the particle, and AREA is the projected area of the particle)

The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape factor SF-2 indicates the degree of unevenness of the toner particles.

By controlling these shape factors,
It is possible to improve the fusion of the toner on the toner carrier and the contamination of the surface of the charging member when a large number of images are printed, and further improve the durability.

In the case of 140 <SF-1, the toner becomes distant from the spherical shape and approaches an irregular shape, the toner is easily crushed in the developing device, the particle size distribution is varied, and the charge amount distribution is broadened. Development of toner on the non-image area, so-called fog, is likely to occur.

When 140 <SF-2, the transfer efficiency of the toner from the photosensitive member to the transfer material such as paper is lowered, and the charging property is deteriorated particularly in the cleanerless structure, which is not preferable.

The toner of the present invention has a weight average particle diameter of 1 to 1.
When it is 9 μm, it is possible to stably obtain a very high quality image for a long period of time.

It is generally known that the finer the particle size of the toner, the higher the resolution at the time of development, but in addition to the increase in the surface area of the entire toner, the fluidity and agitation property of the toner powder are lowered. However, it becomes difficult to uniformly charge the individual particles.

However, the toner SF-1 and SF
By controlling -2 as described in the present invention, it becomes possible to uniformly charge individual particles even with a toner having a small particle diameter, and it is possible to obtain a high-definition image for a long period of time.

The binder resin usable in the toner of the present invention is
All known materials can be used.

For example, a colorant consisting of dye / pigment or a charge control agent is melt-mixed in a thermoplastic resin and uniformly dispersed, and then a toner having a desired particle diameter is produced by a fine pulverizer and a classifier. In the method, the so-called pulverization method, homopolymers of styrene and its substitution products such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, 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-based copolymers such as styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, Epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin,
Phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination.

On the other hand, in the toner production method by the polymerization method, for example, styrene, o (m
Styrene-based monomers such as-, p-)-methylstyrene and m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic Butyl acid, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate,
(Meth) acrylic acid ester monomers such as 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate; butadiene, isoprene, cyclohexene, (meth) acrylonitrile, acrylic Monomers such as acid amides are preferably used. These may be used alone or generally in the Polymer Handbook, Second Edition, Second Edition, pl39-192.
(The John Wiley & Sons company make) The theoretical glass transition temperature (Tg) of 40-75 degreeC is used, and it mixes and uses a monomer suitably. Theoretical glass transition temperature is 4
When the temperature is lower than 0 ° C, problems occur in terms of storage stability of the toner and durability stability of the developer, and when the temperature is higher than 75 ° C, the fixing point is increased. However, the color reproducibility is poor, and the transparency of the OHP image is significantly reduced, which is not preferable in terms of high image quality. At that time, if at least either divinylbenzene or a polyester resin is contained, an appropriate network is formed in the toner, the fixing property and the durability are further improved, and if a saturated polyester resin is further added, the charging is improved. The liquidity, liquidity and environmental stability can be further improved.

In the present invention, when the toner is produced by the polymerization method, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the colorant, and preferably the surface modification, for example,
It is better to apply a hydrophobic treatment with a substance that does not inhibit polymerization. A preferred method of surface-treating a dye system is a method of polymerizing a polymerizable monomer in the presence of these dyes in advance, and the obtained colored polymer is added to the monomer system.

The polymerization initiator used in the present invention for polymerization in an aqueous medium is, for example, 2,2'-azobis-
(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2, Azo-based polymerization initiators such as 4-dimethylvaleronitrile and azobisisobutyronitrile; peroxide-based initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide A polymerization initiator is used.

The amount of the polymerization initiator added varies depending on the desired degree of polymerization, but is generally 0.5 to 2 with respect to the monomer.
It is used by adding 0% by weight. Although the kind of the initiator varies slightly depending on the polymerization method, it may be used alone or in combination with reference to the 10-hour half-life temperature.

To control the degree of polymerization, known crosslinking agents, chain transfer agents, polymerization inhibitors and the like can be further added and used.

As the dispersant used in the polymerization step in the aqueous medium of the present invention, for example, inorganic oxides such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate,
Calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic material,
Examples include ferrite. Examples of organic compounds include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose,
Starch or the like is used by dispersing it in an aqueous phase. These dispersants are used in an amount of 0.2 to 10 with respect to 100 parts by weight of the polymerizable monomer.
It is preferred to use parts by weight.

As these dispersants, commercially available ones may be used as they are, but in order to obtain dispersed particles having a fine and uniform particle size, the inorganic compound should be produced in a dispersion medium under high speed stirring. You can also For example, in the case of tricalcium phosphate, a dispersant suitable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high speed stirring. Further, in order to make these dispersants finer, 0.001 to 0.1 part by weight of a surfactant may be used in combination. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used, and examples thereof include sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, and olein. Calcium acid or the like is preferably used.

When the toner of the present invention is produced by the polymerization method, the toner can be specifically produced by the following method. Colorant, charge control agent, polymerization initiator and other additives are added to the monomer, and the monomer composition is uniformly dissolved or dispersed by a homogenizer, ultrasonic disperser, etc., containing a dispersion stabilizer. Disperse it in the aqueous phase using an ordinary stirrer, homomixer, homogenizer, etc. Granulation is performed by adjusting the stirring speed and time so that droplets of the monomer composition preferably have a desired toner particle size. After that, stirring may be performed to the extent that the particle state is maintained and the particles are prevented from settling due to the action of the dispersion stabilizer. The polymerization temperature is set to 40 ° C. or higher, generally 50 to 90 ° C. to carry out the polymerization. Further, the temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving the durability characteristics in the image forming method of the present invention, the second half of the reaction in order to remove unreacted polymerizable monomers, by-products, etc. Alternatively, the aqueous medium may be partially distilled off after completion of the reaction. After the reaction is completed, the produced toner particles are collected by washing and filtration and dried. In this method, usually 10
It is preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 0 parts by weight.

As the colorant used in the toner of the present invention, known dyes and pigments are used.

Examples of the yellow toner include yellow lead, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hansa yellow G, permanent yellow NCG, benzidine yellow condensed azo compound, isoindolinone compound, anthraquinone compound and azo. Compounds represented by metal complexes, methine compounds, and allylamide compounds, specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 7
4, 83, 93, 94, 95, 109, 110, 11
1,128,129,147,168 etc. are used suitably.

For the magenta toner, for example, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds and the like are used. Specifically, C.I.
I. Pigment Red 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 21, 22, 23, 30, 31, 3
2, 37, 38, 39, 40, 41, 48, 49, 5
0, 51, 52, 53, 54, 55, 57, 58, 6
0, 62, 63, 64, 68, 74, 81, 83, 8
7, 88, 89, 90, 93, 94, 95, 109, 1
10, 111, 112, 114, 122, 123, 12
8, 129, 146, 147, 150, 163, 16
8, 184, 202, 206, 207, 209, 23
8; C.I. I. Pigment Violet 19; C.I. I. Butt Red 1, 2, 10, 13, 15, 23, 29, 3
5 and the like are preferably used.

For the cyan toner, for example, a copper phthalocyanine compound and its derivative, a basic dye lake compound, etc. are used. Specifically, C.I. I. Pigment Blue 1,
7, 15, 15: 1, 15: 2, 15: 3, 15: 4,
60, 62, 66 and the like are preferably used.

The content of these dyes and pigments is OHP.
The amount is preferably 0.5 to 12 parts by weight with respect to 100 parts by weight of the resin for toner so as to sensitively reflect the light transmittance of the film.

In the present invention, it is desirable to add a charge control agent to the toner material in order to control the chargeability of the toner. Examples of these charge control agents include quaternary ammonium salts, guanidine derivatives, imidazole derivatives, amine-based and polyamine-based compounds as positive charge control agents, and negative charge control agents include metals of aromatic carboxylic acid derivatives. Examples thereof include salts or metal complexes, urea derivatives, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers.

Among these, it has a high charge imparting ability,
Further, by using a metal salt or a metal complex of an aromatic carboxylic acid derivative capable of improving powder fluidity, a higher resolution image can be obtained. The addition amount of these charge control agents is preferably 0.1 to 10% by weight.

The toner of the present invention has a softening point of 40 to 90 ° C.
It is also one of the preferable usage forms to contain the wax.

As described above, the toner particles of 1 μm or less enter the gaps between the fibers of the paper when a transfer target such as paper is used, and the heat reception from the heat fixing roller becomes insufficient, resulting in low temperature offset. Likely to happen. Therefore, generally, a means for incorporating a wax component into the toner to improve the releasability from the heat fixing roller is taken. However, it is very difficult to uniformly disperse such a wax component in all the toner particles, and many toner particles having a particularly small particle diameter have a small wax content, and offset is likely to occur. Since the toner of the present invention strictly controls the number of particles of 1 μm or less, even if a general wax is used, offset is less likely to occur as compared with the normal toner, but it is still insufficient. I can not say. Therefore, as in the present invention, by incorporating a wax having a softening point of 40 to 90 ° C. as a release agent into a toner whose particle size distribution is strictly controlled, a toner excellent in offset resistance while maintaining high resolution is obtained. Can be obtained.

However, by incorporating a wax as a release agent into the toner as in the present invention, both high resolution and offset resistance can be achieved.

The waxes used in the present invention include:
Paraffin / polyolefin waxes, ester waxes and modified products thereof, for example, oxides and graft-treated products, higher fatty acids, metal salts thereof, amide waxes, and the like. These waxes are the ball and ball method (J
Those having a softening point of 40 to 90 ° C. according to IS K2531) are desirable. If the softening point is less than 40 ° C., the blocking resistance and shape retention of the toner will be insufficient, and if it exceeds 90 ° C., the effect of releasability will be obtained. Will be insufficient.

These waxes may be used alone or in combination, and the addition amount is preferably 0.1 to 50% by weight.

The toner of the present invention may be used by further adding a fluidity improver. The fluidity improver is not particularly limited as long as it can improve the fluidity after addition by being added to the toner particles. For example, silica fine powder, titanium oxide fine powder, alumina fine powder, and those having their surfaces subjected to a hydrophobic treatment can be used alone or in combination of two or more.

The toner of the present invention may be used as a one-component phenomenon agent or may be used in combination with a carrier as a two-component phenomenon agent. Examples of the carrier include conventionally known carriers such as iron powder, magnetite powder, ferrite powder, glass beads, and magnetic powder dispersed in resin. The surface of these carriers may be coated with a resin, etc., if necessary. Examples of the resin used in this case include a fluorine-containing resin, a phenol resin, a styrene resin, an acrylic resin, and a styrene-acrylic copolymer. , Silicone resin and the like. These coating resins may be used alone or in combination of two or more kinds. When the mixing ratio of the toner and the carrier is 1 to 15% by weight, preferably 2 to 13% by weight as the toner concentration in the developer, good results are usually obtained.

The toner of the present invention is particularly effective when the charging means is a direct charging method in which the charging member is brought into contact with the photosensitive member. That is, if there is a lot of residual toner after cleaning,
It adheres directly to the charging member, which is a post process, and causes charging failure. Therefore, the amount of residual toner is smaller than that of corona discharge in which the charging unit does not contact the photoconductor.
It should be less and less sticky. The preferable conditions for the developing step used in the present invention are that the developer and the surface of the photoreceptor are in contact with each other and that the reversal developing method is used. At this time, at the time of development or at the time of blank before and after development, a bias of DC or AC component is applied, and the potential is controlled so that development and residual toner on the photoconductor can be collected. At this time, the DC component is located between the light portion potential and the dark portion potential.

In the case of a one-component developer, an elastic roller is used as a toner carrier, and the surface of the elastic roller or the like is coated with toner, and this is brought into contact with the surface of the photoreceptor. At this time, it is important that the toner is in contact with the surface of the photoconductor. In this case, since cleaning is performed at the same time as development by the electric field acting between the photoconductor and the elastic roller facing the surface of the photoconductor via the toner, the surface of the elastic roller or the vicinity of the surface has a potential, and the surface of the photoconductor and the toner There is a need to have an electric field in the narrow gaps of the support surface. For this reason, the elastic rubber of the elastic roller is resistance-controlled in the medium resistance region to maintain the electric field while preventing conduction with the surface of the photoconductor, or a method of providing a thin insulating layer on the surface layer of the conductive roller can be used. . Further, it is also possible to adopt a configuration in which a conductive resin sleeve in which the side facing the surface of the photoconductor is coated with an insulating material is provided on the conductive roller, or a conductive layer is provided on the side not facing the photoconductor with the insulating sleeve. It is also possible to use a rigid roller as the toner carrier and make the photosensitive member flexible such as a belt. The resistance of the developing roller as a toner carrier is 1
The range of 0 ² to 10 ⁹ Ω · cm is preferable.

When the one-component contact developing method is used, the surface of the roller carrying the toner and the peripheral speed of the photosensitive member may rotate in the same direction or in the opposite direction. When the rotations are in the same direction, the peripheral speed ratio to the peripheral speed of the photoconductor is preferably 100% or more. If it is less than 100%, the image quality is poor. The higher the peripheral speed ratio, the greater the amount of toner supplied to the development site, the more frequently toner is desorbed from the latent image, and the unnecessary parts are scraped off and applied to the necessary parts. As a result, an image faithful to the latent image can be obtained. From the viewpoint of simultaneous development and cleaning,
Since the effect of physically peeling off the transfer residual toner adhered to the photoconductor on the surface of the photoconductor and the toner adhesion part by the peripheral speed difference and collecting by the electric field can be expected, the higher the peripheral speed ratio, the more the transfer residual It is convenient for toner recovery.

One of the preferable structures of the image forming method according to the present invention will be specifically described with reference to FIG.

In FIG. 2, 20 is a developing device, 29 is a photoconductor, 25 is a transfer target such as paper, 26 is a transfer member, and 27 is a transfer member.
Is a pressure roller for fixing, 28 is a heating roller for fixing, 3
Reference numeral 0 denotes a primary charging member that comes into contact with the photosensitive member 29 and is directly charged.

A bias power source 35 is connected to the primary charging member 30 so as to uniformly charge the surface of the photoconductor 29.

The developing device 20 contains the toner 24 and is provided with a toner carrier 22 which comes into contact with the photosensitive member 29 and rotates in the direction of the arrow. Further, a developing blade 21 for toner amount regulation and charge imparting, a toner 24 is applied to the toner carrier 22 and a coating roller 23 rotating in the arrow direction in order to impart the charge to the toner by friction with the toner carrier 22. Is also equipped. A development bias power source 37 is connected to the toner carrier 22. A bias power source 38 is also connected to the coating roller 23, and a voltage is set to the negative side of the developing bias when the negative charging toner is used and to the positive side of the developing bias when the positive charging toner is used. To be done.

A transfer bias current 36 having a polarity opposite to that of the photosensitive member 29 is connected to the transfer member 26.

Here, the length in the rotational direction at the contact portion between the photosensitive member 29 and the toner carrier 22, that is, the so-called developing nip width, is preferably 0.2 mm or more and 8.0 mm or less. 0.2
If it is less than mm, the amount of development is insufficient and a satisfactory image density cannot be obtained, and the residual toner after transfer is insufficiently collected. If it exceeds 8.0 mm, the toner supply amount becomes excessive, the fog suppression is apt to be deteriorated, and the abrasion of the photoconductor is also adversely affected.

As the toner carrier, a so-called elastic roller having an elastic layer on its surface is preferably used. The hardness of the elastic layer material used is 20 to 65 degrees (J
ISA) is preferably used. Further, the resistance of the toner carrier is preferably in the range of about 10 ³ to 10 ⁹ Ωcm in terms of volume resistance value. When it is lower than 10 ³ Ωcm, for example, when there is a pinhole on the surface of the photoconductor 29, an overcurrent may flow. On the other hand, when it is higher than 10 ⁹ Ωcm, toner charge-up due to triboelectric charging is apt to occur and the image density is apt to be lowered.

The toner coat amount on the toner carrier is 0.
It is preferably 1 mg / cm ² or more and 1.5 mg / cm ² or less.
When it is less than 0.1 mg / cm ^2, it is difficult to obtain a sufficient image density, and when it is more than 1.5 mg / cm ^2, it becomes difficult to uniformly triboelectrically charge all individual toner particles.
It causes deterioration of fog control. Furthermore, 0.2 mg /
More preferably, it is not less than cm ^{2 and not} more than 0.9 mg / cm ² .

The toner coating amount is suppressed by the developing blade 21, which is in contact with the toner carrier 22 via the toner layer. The contact pressure at this time is preferably 5 g / cm or more and 50 g / cm or less. If it is less than 5 g / cm, uniform triboelectric charging becomes difficult in addition to the control of the toner coat amount, which causes deterioration of fog suppression. On the other hand, when it is more than 50 g / cm, the toner particles are excessively loaded, so that the deformation of the particles and the fusion of the toner to the developing blade or the toner carrier easily occur, which is not preferable.

In FIG. 2, the primary charging member 30 uniformly charges the photoconductor 29 rotating in the direction of the arrow. Then, an exposure 31 from the light emitting element forms an electrostatic latent image on the photoconductor 29 according to the information signal, and the electrostatic latent image is developed with toner at a position where the electrostatic latent image comes into contact with the toner carrier 22 to be visualized. . Next, the visible image is transferred by the transfer member 26 to the transfer target 2
5, and the transfer toner 32 passes through between the heating roller 28 and the pressure roller 27 together with the transferred material 25 and is fixed, thereby obtaining a permanent image.

At this time, the untransferred toner 33 remaining on the photosensitive member 29 without being transferred is the photosensitive member 29 and the primary charging member 30.
After passing through the space, it reaches the developing nip portion again and is collected in the developing device 20 by the toner carrier 22.

Next, various measuring methods in the present invention will be described.

(1) Measurement of transmitted light spectrum In the present invention, Shimadzu self-recording spectrophotometer, UV-220.
It is measured using 0 (manufactured by Shimadzu Corporation).

Accurately weigh about 10 mg of the measurement sample,
Ultrasonic dispersing device U was added to a 30 ml sample bottle containing 10 ml of ion-exchanged water containing a dispersing surfactant.
Disperse with H-50 (SMT COMPANY) for 10 minutes. The ultrasonic dispersion intensity at this time is 4 to 8,
If the tip of the ultrasonic vibrating part is inserted to a depth of about 5 mm from the sample liquid surface and tuned so that the dispersion energy is maximized, good dispersion can be obtained without crushing the sample toner particles. After adding 10 ml of ion-exchanged water to the obtained sample dispersion aqueous solution to reduce the sample concentration to 1/2, the sample was put into a quartz cell having a light transmission distance of 1 cm to obtain a wavelength of 200 nm to 90 nm.
The transmitted light spectrum is measured in the region of 0 nm.

At this time, the sample concentration was changed to C (g / liter)-
1 and the absorbances at wavelengths 260 and 400 nm obtained from the measured spectrum are a and b, respectively, A = a / C B = b / C.

(2) Method of measuring triboelectric charge amount FIG. 1 is an explanatory view of an apparatus for measuring the toner charge amount.
First, in a metal measuring container 12 having a 500 mesh screen 13 at the bottom, about 0.5 to 1.0 g of a mixture of toner and carrier (developer) whose triboelectric charge amount is to be measured.
And put on the lid 14 made of metal. The weight of the entire measuring container 12 at this time is weighed and is W1 (kg). Next, in the suction device 11 (at least the portion in contact with the measurement container 12 is an insulator), the pressure of the vacuum gauge 15 is adjusted to 2450 Pa (250 mmAq) by sucking through the suction port 16 and adjusting the air volume. In this state, the toner is sucked sufficiently, preferably for about 2 minutes to suck and remove the toner. The potential of the electrometer 18 at this time is V
(Bolt). Here, 17 is a capacitor, and the capacity is C (mF). The weight of the entire measuring container after suction is weighed and is W2 (kg). The triboelectric charge amount (mC / kg) of the toner at this time is calculated by the following formula.

Toner triboelectric charge amount (mC / kg) = (C
× V) / (W1-W2)

(3) Average particle size and particle size distribution of toner As for the average particle size and particle size distribution of toner, Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co.) is used to output number distribution and volume distribution. An interface (made by Nikkaki) and a PC9801 personal computer (made by NEC) are connected, and the electrolyte is 1
Prepare a 1% aqueous NaCl solution using graded sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As the measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) as a dispersant is added to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and 100% was obtained as a rear aperture by the Coulter Counter TA-II type.
The volume distribution and the number distribution were calculated by measuring the volume and number of the toner having a particle size of 2 μm or more using a μm aperture.
Then, the volume-based weight average particle diameter (D4) determined from the volume distribution according to the present invention was determined.

[0105]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Yellow Color Toner : [Polymerized Toner Production Example 1] To 710 g of ion-exchanged water in a 2-liter four-necked flask, 450 g of 0.1 M Na ₃ PO ₄ aqueous solution was added and heated to 60 ° C. After that, using a high-speed stirring device TK type homomixer (made by Tokushu Kika Kogyo),
It was stirred at 12000 rpm. 1.0M-Ca
68 g of an aqueous Cl ₂ solution was gradually added to obtain an aqueous dispersion medium containing minute dispersion stabilizers having poor water solubility.

On the other hand, as a dispersoid (monomer) styrene 160 g n-butyl acrylate 40 g (colorant) C.I. I. Pigment Yellow 178 g (charge control agent) 2,5-di-tert-butylsalicylic acid Al compound 4 g (release agent) polypropylene wax (softening point 135 ° C.) 10 g (other) saturated polyester resin 10 g In the formulation, only the colorant, the Al compound of di-tert-butylsalicylic acid, and styrene were premixed using an Ebara Milder (manufactured by Ebara Corporation).
Next, all of the above formulations were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Furthermore, while maintaining at 60 ℃,
10 g of an initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.

The above monomer composition was added to the aqueous dispersion medium prepared in the 2 liter flask of the homomixer. The monomer composition was granulated by stirring at 60 ° C. for 20 minutes at 10,000 rpm using a TK homomixer in a nitrogen atmosphere. Then, while stirring with a paddle stirring blade, 60
After reacting at 6 ° C for 6 hours, polymerization was performed at 80 ° C for 10 hours.

After the completion of the polymerization reaction, the reaction product was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) _2, and the suspension was filtered, washed with water and dried to give colored suspension particles having a weight average diameter of about 6.7 μm. Got 1.

With respect to 100 parts by weight of the obtained colored suspension particles, the surface of the silica matrix having a specific surface area of 200 m ² / g by the BET method was subjected to a hydrophobic treatment with a silane coupling agent and silicone oil to obtain a specific surface area. Polymerized toner 1 was obtained by externally adding 1.5 parts by weight of hydrophobic silica having a volume of 120 m ² / g. Various physical properties of the obtained polymerized toner 1 are shown in Table 1.

Before and after externally adding the hydrophobic silica,
Since the A / B values were the same, all the A / B values in the physical property values in the subsequent toner production examples are the values after external addition.

[Production Example 2 of Polymerized Toner] Using the same materials as in Production Example 1 of polymerized toner, an aqueous dispersion medium and a monomer composition were prepared by the same means.

The monomer composition was added to an aqueous dispersion medium prepared in a 2 liter flask of a homomixer. 60
1 ° C using a TK homomixer with nitrogen atmosphere
The mixture was stirred at 0000 rpm for 20 minutes to granulate the monomer composition. Then, the mixture was reacted with the paddle stirring blade at 60 ° C. for 6 hours and then polymerized at 90 ° C. for 10 hours.

After the completion of the polymerization reaction, the reaction product is cooled, hydrochloric acid is added to dissolve Ca ₃ (PO ₄ ) _2, and the suspension is filtered, washed with water and dried to give colored suspension particles having a weight average diameter of about 6.8 μm. Got

Next, the obtained colored suspended particles were subjected to particle size distribution adjustment with a hot air treatment device. The colored suspended particles were introduced into a hot air stream with a hot air inlet temperature of 160 ° C.
The number of particles of 1 μm or less was adjusted by coalescing particles of μm or less to obtain colored suspended particles 2. Production Example 1 of polymerized toner based on 100 parts by weight of the obtained colored suspended particles.
Externally added 1.5 parts by weight of the hydrophobic silica used in Example 1 to obtain a polymerized toner 2 having the physical properties shown in Table 1.

[Production Examples 3 and 4 of Polymerized Toner] The same materials as in Production Example 1 of polymerized toner were used, except that the polypropylene wax was changed to an ester wax (softening point 75 ° C.) as a release agent. After changing the amount of the stabilizer, the stirring conditions and the polymerization temperature to obtain colored suspended particles, the colored suspended particles are subjected to the same heat treatment as in Production Example 2 of the polymerized toner, and the excess particles of 1 μm or less are combined. By adjusting the number of particles of 1 μm or less, colored suspended particles 3 having a weight average diameter of about 5.3 μm and colored suspended particles 4 having a weight average diameter of about 9.1 μm were obtained. To 100 parts by weight of the obtained colored suspended particles, 2.0 parts by weight and 1.0 part by weight of the hydrophobic silica used in Production Example 1 of polymerized toner were added externally. Polymerized toner 3 and polymerized toner 4 were obtained.

[Production Example 5 of polymerized toner] The same material as in Production Examples 3 and 4 of polymerized toner was used, and the weight average diameter was about 6.3 μm.
To obtain colored suspended particles of.

Next, the obtained colored suspended particles were subjected to particle size distribution adjustment by a hot air treatment device. The colored suspended particles were introduced into a hot air stream having a hot air inlet temperature of 350 ° C.
The number of particles of 1 μm or less was adjusted by coalescing particles of μm or less to obtain colored suspended particles 5 having a weight average diameter of about 7.2 μm. To 100 parts by weight of the obtained colored suspended particles, 1.5 parts by weight of the hydrophobic silica used in Production Example 1 of polymerized toner was externally added to obtain a polymerized toner 5 having the physical properties shown in Table 1. .

[0119]   [Production Example 1 of pulverized toner] (Resin) Styrene-butyl acrylate copolymer (copolymerization ratio 80:20)                                                           100 parts by weight (Colorant) C.I. I. Pigment Yellow 174 4 parts by weight (Charge control agent) Al compound of 2,5-di-tert-butylsalicylic acid                                                               2 parts by weight (Release agent) Ester wax (softening point 75 ° C) 3 parts by weight (Other) Saturated polyester resin 5 parts by weight

The above materials were mixed in advance and melt-kneaded at 130 ° C. with a twin-screw extruder. The melt-kneaded product was crushed with a hammer mill to obtain a 1-mm mesh-pass toner crushed product. Further, this coarsely pulverized product was finely pulverized by a collision type pulverizer using a jet stream and then classified by wind force to obtain a colored powder 1 having a weight average particle diameter of 9.8 μm. To 100 parts by weight of the obtained colored powder, 1.0 part by weight of the hydrophobic silica used in Production Example 1 of polymerized toner was externally added to obtain pulverized toner 1. Table 1 shows the physical properties of the obtained toner.

[Production Example 2 of pulverized toner] Using the same materials as in Production Example 1 of pulverized toner and obtaining colored particles by the same means, the particles were added to an aqueous solution containing a surfactant and stirred at a high speed. After treatment at 70 ° C for 2 hours, filtration, washing with water,
After drying, colored powder 2 having a weight average diameter of about 9.9 μm was obtained. To 100 parts by weight of the obtained colored powder, 1.0 part by weight of the hydrophobic silica used in Production Example 1 of polymerized toner was externally added to obtain pulverized toner 2. Table 1 shows the physical properties of the obtained toner.

[Production Example 3 of pulverized toner] Using the same material as in Production Example 1 of pulverized toner and obtaining colored powder by the same means, the obtained colored powder is introduced into a hot air stream having a hot air inlet temperature of 160 ° C. Then, the number of particles of 1 μm or less was adjusted by coalescing excess particles of 1 μm or less. Then, the mixture was added to an aqueous solution containing a surfactant, spheronized at 70 ° C. for 2 hours while stirring at high speed, filtered, washed with water and dried to give a colored powder 3 having a weight average diameter of about 9.7 μm. Got 1.0 part by weight of the hydrophobic silica used in Production Example 1 of polymerized toner was externally added to 100 parts by weight of the obtained colored powder to obtain a pulverized toner 3. Table 1 shows the physical properties of the obtained toner.

[0123]

[Table 1]

<Examples 1 to 4, Reference Example 1 , Comparative Examples 1 to 3
> A 600 dpi laser beam printer (LBP-860 manufactured by Canon Inc.) was prepared as an electrophotographic apparatus. The process speed is 47 mm / s.

The cleaning rubber blade in this process cartridge was removed, and the charging system of the apparatus was set to direct charging by contacting a rubber roller, and the applied voltage was set to a DC component (-1400 V).

Next, the developing portion of the process cartridge was modified. A medium resistance rubber roller (16φ, hardness ASKER C 45 degrees, resistance 10 ⁵ Ω.
cm) was used as a toner carrying member and was brought into contact with the photoconductor. The developing nip width at this time was set to about 2 mm. The rotational peripheral speed of the toner carrier is in the same direction at the contact portion with the photoconductor, and the toner is driven to be 130% of the rotational peripheral speed of the photoconductor.

The photosensitive member used here is 30φ, 2
A 54 mm Al cylinder was used as a base, and layers having the following constitution were sequentially laminated by dip coating to prepare a photoconductor.

(1) Conductive coating layer: Mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin. Film thickness 15 μm.

(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. The film thickness is 0.6 μm.

(3) Charge generation layer: Mainly composed of a butyral resin in which a titanyl phthalocyanine pigment having absorption in a long wavelength region is dispersed. The film thickness is 0.6 μm.

(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by Ostwald viscosity method) at a weight ratio of 8:10. Film thickness 20 μm.

As a means for applying toner to the toner carrier, an application roller made of foamed urethane rubber was provided in the developing device and brought into contact with the toner carrier. For the coating roller,
A voltage of about -550V is applied. Further, a resin-coated stainless steel blade was attached for controlling the toner coating layer on the toner carrier. The outline is shown in FIG. Further, the applied voltage at the time of development was only the DC component (-450V).

The electrophotographic apparatus was modified and the process conditions were set as follows so as to be compatible with the modification of these process cartridges.

The modified apparatus uses a roller charger (applying only direct current) to uniformly charge the image bearing member. After charging, an electrostatic latent image is formed by exposing the image portion with a laser beam, and a visible image is formed with toner, and then the toner image is transferred onto a transfer material by a roller to which a voltage is applied. The outline is shown in FIG.

As for the charging potential of the photosensitive member, the dark part potential is -8.
The light potential was set to 00V and the light portion potential was set to -150V. 75 g / m ² of paper was used as the transfer material.

Depending on the image forming apparatus, polymerized toners 1 to 5 are used.
And using pulverized toners 1 to 3, temperature 23 ° C./humidity 60
The durability test was conducted under the condition of%.

In the durability evaluation, characters were printed at a printing area ratio of 4%, and the judgment was made by the number of stains generated on the image due to charging failure and the density of the solid image by Macbeth at that time. When the stain did not occur, the image printing was continued up to 1000 sheets. The more stains there are, the more
The higher the image density at that time is, the better the durability is.

Further, the amount of toner attached to the charging roller at the end of the durability test was measured. The dirt on the charging roller is the toner weight per unit area on the charging roller (mg / c
m ² ) was measured.

Further, the transferability in the initial stage of durability is as follows. The transfer residual toner on the solid photoconductor is taped off with Mylar tape and stripped off, and the Macbeth density of the one stuck on the paper is changed to the Macbeth density of the one stuck on the paper. Evaluation was made with the subtracted numerical values. Therefore, the smaller the value, the better the transferability. The resolving power at the initial stage of durability was evaluated by the reproducibility of one small dot with a small diameter at 600 dpi, which is difficult to reproduce because the electric field is easily closed by the latent image electric field.

[0140] ◎ Very good: 5 defects or less in 100 Good: 6 to 10 defects in 100 △ Practically acceptable: 11 to 20 defects in 100 × Practical use: 20 or more defects in 100

For the evaluation of the low temperature offset property, the back side of the image sample was observed from the beginning of the durability to 100 sheets of durability, and it was checked whether or not the image back stain occurred.

The results are shown in Table 2.

[0143]

[Table 2]

Magenta Toner : [Polymerized Toner Production Example 6] To 710 g of ion-exchanged water in a 2-liter four-necked flask, 450 g of 0.1 M Na ₃ PO ₄ aqueous solution was added, and after heating to 60 ° C. , Using a high speed mixer TK homomixer (made by Tokushu Kika Kogyo)
It was stirred at 12000 rpm. 1.0M-Ca
68 g of an aqueous Cl ₂ solution was gradually added to obtain an aqueous dispersion medium containing minute dispersion stabilizers having poor water solubility.

On the other hand, as a dispersoid, (monomer) styrene 160 g n-butyl acrylate 40 g (colorant) C.I. I. Pigment Red 202 8 g (charge control agent) 2,5-di-tert-butylsalicylic acid Al compound 4 g (release agent) polypropylene wax (softening point 135 ° C.) 10 g (others) Saturated polyester resin 10 g was prepared, and the above formulation was prepared. Of these, only the colorant, the Al compound of di-tert-butylsalicylic acid, and styrene were premixed using an Ebara Milder (manufactured by Ebara Corporation).
Next, all of the above formulations were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Furthermore, while maintaining at 60 ℃,
10 g of an initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.

The above monomer composition was added to the aqueous dispersion medium prepared in the 2 liter flask of the homomixer. The monomer composition was granulated by stirring at 60 ° C. for 20 minutes at 10,000 rpm using a TK homomixer in a nitrogen atmosphere. Then, while stirring with a paddle stirring blade, 60
After reacting at 6 ° C for 6 hours, polymerization was performed at 80 ° C for 10 hours.

After the completion of the polymerization reaction, the reaction product is cooled, hydrochloric acid is added to dissolve Ca ₃ (PO ₄ ) _2, and the suspension is filtered, washed with water and dried to give colored suspended particles having a weight average diameter of about 6.6 μm. Got 6.

With respect to 100 parts by weight of the obtained colored suspended particles, the surface of the silica matrix having a specific surface area of 200 m ² / g by the BET method was hydrophobized with a silane coupling agent and silicone oil to obtain a specific surface area. Polymerized toner 6 was obtained by externally adding 1.5 parts by weight of hydrophobic silica having a volume of 120 m ² / g. Table 3 shows the physical properties of the obtained polymerized toner 6.

[Production Example 7 of polymerized toner] The same materials as in Production Example 6 of polymerized toner were used to prepare an aqueous dispersion medium and a monomer composition.

The monomer composition was added to the aqueous dispersion medium prepared in a 2 liter flask of a homomixer. 60
1 ° C using a TK homomixer with nitrogen atmosphere
The mixture was stirred at 0000 rpm for 20 minutes to granulate the monomer composition. Then, the mixture was reacted with the paddle stirring blade at 60 ° C. for 6 hours and then polymerized at 90 ° C. for 10 hours.

After the completion of the polymerization reaction, the reaction product was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) _2, and the suspension was filtered, washed with water and dried to give colored suspension particles having a weight average diameter of about 6.7 μm. Got

Next, the obtained colored suspended particles were subjected to particle size distribution adjustment with a hot air treatment device. The colored suspended particles were introduced into a hot air stream with a hot air inlet temperature of 160 ° C.
The number of particles of 1 μm or less was adjusted by uniting particles of μm or less to obtain colored suspended particles 7. Production Example 6 of polymerized toner based on 100 parts by weight of the obtained colored suspended particles.
Externally added was 1.5 parts by weight of the hydrophobic silica used in Example 3 to obtain a polymerized toner 7 having the physical properties shown in Table 3.

[Polymerized Toner Production Examples 8 and 9] The same material as in Polymerized Toner Production Example 6 was used except that the polypropylene wax was changed to an ester wax (softening point 75 ° C.) as the release agent. After changing the amount of the stabilizer, the stirring conditions and the polymerization temperature to obtain colored suspension particles, the colored suspension particles are subjected to the same heat treatment as in Production Example 7 of polymerized toner, and the excess particles of 1 μm or less are combined. By adjusting the number of particles of 1 μm or less, colored suspended particles 8 having a weight average diameter of about 5.4 μm and colored suspended particles 9 having a weight average diameter of about 9.1 μm were obtained. To 100 parts by weight of the obtained colored suspended particles, 2.0 parts by weight and 1.0 part by weight of the hydrophobic silica used in Production Example 6 of polymerized toner were added, respectively. Polymerized toner 8 and polymerized toner 9 were obtained.

[Production Example 10 of polymerized toner] The same material as in Production Examples 8 and 9 of polymerized toner was used, and the weight average diameter was about 6.2 μm.
m colored suspended particles were obtained.

Next, the obtained colored suspended particles were subjected to particle size distribution adjustment with a hot air treatment device. The colored suspended particles were introduced into a hot air stream having a hot air inlet temperature of 350 ° C.
The number of particles of 1 μm or less was adjusted by coalescing particles of μm or less to obtain colored suspended particles 10 having a weight average diameter of about 7.0 μm. To 100 parts by weight of the obtained colored suspended particles, 1.5 parts by weight of the hydrophobic silica used in Production Example 6 of polymerized toner was externally added to obtain a polymerized toner 10 having the physical properties shown in Table 3. .

[0156]   [Production Example 4 of pulverized toner] (Resin) Styrene-butyl acrylate copolymer (copolymerization ratio 80:20)                                                           100 parts by weight (Colorant) C.I. I. Pigment Red 202 4 parts by weight (Charge control agent) Al compound of 2,5-di-tert-butylsalicylic acid                                                               2 parts by weight (Release agent) Ester wax (softening point 75 ° C) 3 parts by weight (Other) Saturated polyester resin 5 parts by weight

The above materials were mixed in advance and melt-kneaded at 130 ° C. with a twin-screw extruder. The melt-kneaded product was crushed with a hammer mill to obtain a 1-mm mesh-pass toner crushed product. Further, this coarsely pulverized product was finely pulverized by a collision type pulverizer using a jet stream and then classified by wind force to obtain a colored powder 4 having a weight average particle diameter of 9.7 μm. To 100 parts by weight of the obtained colored powder, 1.0 part by weight of the hydrophobic silica used in Production Example 6 of polymerized toner was externally added to obtain pulverized toner 4. Table 3 shows the physical properties of the obtained toner.

[Production Example 5 of pulverized toner] Using the same materials as in Production Example 4 of pulverized toner and obtaining colored particles by the same means, the particles were added to an aqueous solution containing a surfactant and stirred at a high speed. After treatment at 70 ° C for 2 hours, filtration, washing with water,
After drying, colored powder 5 having a weight average diameter of about 9.9 μm was obtained. To 100 parts by weight of the obtained colored powder, 1.0 part by weight of the hydrophobic silica used in Production Example 6 of polymerized toner was externally added to obtain pulverized toner 5. Table 3 shows the physical properties of the obtained toner.

[Production Example 6 of pulverized toner] Using the same materials as in Production Example 4 of pulverized toner and obtaining colored powder by the same means, the obtained colored powder was introduced into a hot air stream at 150 ° C. The number of particles of 1 μm or less was adjusted by coalescing particles of 1 μm or less. Then, the mixture was added to an aqueous solution containing a surfactant, spheronized at 70 ° C. for 2 hours while stirring at high speed, filtered, washed with water and dried to give a colored powder 6 having a weight average diameter of about 9.8 μm. Got Obtained colored powder 10
1.0 part by weight of the hydrophobic silica used in Production Example 6 of polymerized toner was externally added to 0 part by weight to obtain a pulverized toner 6. Table 3 shows the physical properties of the obtained toner.

[0160]

[Table 3]

<Examples 5-8, Reference Example 2 , Comparative Examples 4-6
> Examples 1 to 1 of the yellow toner as an image forming apparatus
The modified machine used in 4, using the polymerized toners 6-10 and pulverized toners 4-6, it was subjected to the same endurance test and evaluation as in Example 1-4.

The results are shown in Table 4.

[0163]

[Table 4]

Cyan Toner : [Preparation Example 11 of Polymerized Toner] 0.1M Na ₃ PO ₄ was added to 710 g of ion-exchanged water in a 2-liter four-necked flask.
After adding 450 g of the aqueous solution and heating to 60 ° C., the mixture was stirred at 12000 rpm using a high-speed stirring device TK homomixer (manufactured by Tokushu Kika Kogyo). 1.0M-
68 g of an aqueous CaCl ₂ solution was gradually added to obtain an aqueous dispersion medium containing a minute, slightly water-soluble dispersion stabilizer.

On the other hand, as a dispersoid (monomer) styrene 160 g n-butyl acrylate 40 g (colorant) C.I. I. Pigment Blue 15:38 8 g (charge control agent) 2,5-di-tert-butylsalicylic acid Al compound 4 g (release agent) polypropylene wax (softening point 135 ° C.) 10 g (other) saturated polyester resin 10 g, Of the above formulations, only the colorant, the Al compound of di-tert-butylsalicylic acid, and styrene were premixed using an Ebara Milder (manufactured by Ebara Corporation).
Next, all of the above formulations were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Furthermore, while maintaining at 60 ℃,
10 g of an initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.

The above monomer composition was added to the aqueous dispersion medium prepared in the 2 liter flask of the homomixer. The monomer composition was granulated by stirring at 60 ° C. for 20 minutes at 10,000 rpm using a TK homomixer in a nitrogen atmosphere. Then, while stirring with a paddle stirring blade, 60
After reacting at 6 ° C for 6 hours, polymerization was performed at 80 ° C for 10 hours.

After the completion of the polymerization reaction, the reaction product was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) _2, and the suspension was filtered, washed with water and dried to give colored suspended particles having a weight average diameter of about 6.7 μm. I got 11.

With respect to 100 parts by weight of the obtained colored suspended particles, the surface of the silica matrix having a specific surface area of 200 m ² / g by the BET method was subjected to a hydrophobic treatment with a silane coupling agent and silicone oil to obtain a specific surface area. Polymerized toner 11 was obtained by externally adding 1.5 parts by weight of 120 m ² / g of hydrophobic silica. Table 5 shows the physical properties of the obtained polymerized toner 11.
It was shown to.

[Production Example 12 of Polymerized Toner] The same materials as in Production Example 11 of polymerized toner were used, and the aqueous dispersion medium and the monomer composition were prepared by the same means.

The monomer composition was put into an aqueous dispersion medium prepared in a 2 liter flask of a homomixer. 60
1 ° C using a TK homomixer with nitrogen atmosphere
The mixture was stirred at 0000 rpm for 20 minutes to granulate the monomer composition. Then, the mixture was reacted with the paddle stirring blade at 60 ° C. for 6 hours and then polymerized at 90 ° C. for 10 hours.

After the completion of the polymerization reaction, the reaction product is cooled, hydrochloric acid is added to dissolve Ca ₃ (PO ₄ ) _2, and the suspension is filtered, washed with water and dried to give colored suspension particles having a weight average diameter of about 6.8 μm. Got

Next, the obtained colored suspended particles were subjected to particle size distribution adjustment by a hot air treatment device. The colored suspended particles were introduced into a hot air stream with a hot air inlet temperature of 160 ° C.
The number of particles of 1 μm or less was adjusted by uniting particles of μm or less to obtain colored suspended particles 12. To 100 parts by weight of the obtained colored suspended particles, 1.5 parts by weight of the hydrophobic silica used in Production Example 11 of polymerized toner was externally added to obtain a polymerized toner 12 having the physical properties shown in Table 5. .

[Production Examples 13 and 14 of polymerized toner] The same materials as in Production Example 11 of polymerized toner were used, except that polypropylene wax was changed to ester wax (softening point 75 ° C.) as a release agent, and a slightly water-soluble dispersion was used. After changing the amount of the stabilizer, the stirring conditions and the polymerization temperature to obtain colored suspended particles, the colored suspended particles are subjected to the same heat treatment as in Production Example 12 of the polymerized toner, and the excess particles of 1 μm or less are combined. By adjusting the number of particles of 1 μm or less, the weight average diameter is about 5.3.
Colored suspended particles 13 of μm and colored suspended particles 14 having a weight average diameter of about 9.1 μm were obtained. Obtained colored suspended particles 100
2.0 parts by weight and 1.0 part by weight of the hydrophobic silica used in Production Example 11 for polymerized toner were added externally to the polymerized toner 13 and polymerized toner 14 having the physical properties shown in Table 5, respectively. Got

[Production Example 15 of polymerized toner] The same material as in Production Examples 13 and 14 of polymerized toner was used, and the weight average diameter was about 6.
4 μm colored suspended particles were obtained.

Next, the obtained colored suspended particles were subjected to particle size distribution adjustment with a hot air treatment device. The colored suspended particles were introduced into a hot air stream having a hot air inlet temperature of 350 ° C.
The number of particles of 1 μm or less was adjusted by coalescing particles of μm or less to obtain colored suspended particles 15 having a weight average diameter of about 7.3 μm. To 100 parts by weight of the obtained colored suspended particles, 1.5 parts by weight of the hydrophobic silica used in Production Example 11 of polymerized toner was externally added to obtain a polymerized toner 15 having the physical properties shown in Table 5. .

[0176]

[0177]

[0178]

[0179]

[0180]

[Table 5]

<Examples 9 to 12 , Comparative Example 7> As an image forming apparatus, Examples 1 to 1 of the yellow toner are used.
The modified machine used in 4, using the polymerized toner 11-1 5 was subjected to the same endurance test and evaluation as in Example 1-4.

The results are shown in Table 6.

[0183]

[Table 6]

[0184] <Example 13> Polymerization toner 3,8,13, ferrite career that 0.5 part by weight coating to the silicone resin carrier core
( Average particle size 48 μm) means that the toner concentration in the developer is 5%
3 types of developers are prepared by mixing so that the electrophotographic copying machine CLC-700 (manufactured by Canon Inc.) is used as it is, and the image area ratio is 20% in an environment of temperature 23 ° C./humidity 60%. Using an original document of 10000, a 3-color full-color printing durability test of 10,000 sheets was performed.

As a result, in the case of polymerized toner 3, the initial charge amount was −31.7 mC / kg → after 10,000 sheets, −31.5 m.
C / kg, initial image density 1.56 → after 10,000 sheets 1.
In the case of polymerized toner 8, the initial charge amount was −30.5 mC / kg → after 10,000 sheets, −30.1 mC.
/ Kg, initial image density 1.59 → 1.5 after 10,000 sheets
8 and the polymerization toner 13 was stable, and the initial charge amount was -31.1 mC / kg → after 10,000 sheets-30.9 mC
/ Kg, initial image density 1.58 → after 10,000 sheets 1.5
No. 7 and all the developers remained stable.

Further, with any of the developers, a high-resolution image without image defects such as fog was stably obtained.

[0187]

As described above, when the toner of the present invention is used, a high-resolution image can be obtained without causing image defects due to charging failure and deterioration of developing characteristics even in the simultaneous developing image forming method. Excellent durability is obtained. Further, even when used as a two-component color developer, a high-definition image can be obtained for a long period of time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus that measures a toner charge amount.

FIG. 2 is a schematic view of a process of an electrophotographic apparatus preferably used in the image forming method of the present invention.

[Explanation of symbols]

Reference Signs List 20 developing device 21 coating layer control blade (made of resin-coated stainless steel) 22 toner carrier (medium resistance rubber roller) 23 toner application roller 24 toner 25 transfer material 26 transfer roller 27 fixing pressure roller 28 fixing heating roller 29 Photoconductor 30 Charging roller 31 Laser light

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G03G 15/08 507 G03G 15/08 507L (56) References JP-A-63-244051 (JP, A) JP-A-63-144360 (JP, A) JP 63-108357 (JP, A) JP 62-209542 (JP, A) JP 53-6040 (JP, A) JP 53-5633 (JP, A) Kaihei 9-288373 (JP, A) JP 8-328341 (JP, A) JP 8-305074 (JP, A) JP 8-146652 (JP, A) JP 7-209952 ( JP, A) JP-A-5-11497 (JP, A) JP-A-3-213876 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (10)

(57) [Claims] 1. A cylindrical shape for holding an electrostatic latent image is provided.
Charging step for contacting the charging roller to the latent image holding member to perform primary charging, electrostatic latent image forming step for forming an electrostatic latent image on the latent image holding member that is primarily charged, and developing the electrostatic latent image A developing step by a one-component contact developing method for developing with a chromatic color toner possessed by the apparatus to form a chromatic color toner image on the latent image carrier, a chromatic color formed on the latent image carrier In an image forming method including a transfer step of transferring a color toner image to a recording material, and a fixing step of fixing the chromatic color toner image transferred to the recording material to the recording material, the developing device includes the chromatic color image. Toner is carried to the development area
Having a toner carrier having a cylindrical shape for carrying
Cage, rotating side in the contact portion of the latent image bearing member and the toner carrying member
Has a length of 0.2 to 8.0 mm, and the chromatic color toner has chromatic color toner particles containing at least a binder resin, a colorant and a release agent. The color toner particles have a shape factor SF-2 of 10
0 to 140, and the chromatic color toner has a wavelength of 260 n when the toner concentration is converted into 1 g / liter in a transmitted light spectrum in a state of being dispersed in an aqueous solution.
The ratio (A / B) of the absorbance A at m to the absorbance B at a wavelength of 400 nm when the toner concentration is converted to 1 g / liter is 0.85 to 1.00, and the chromatic color toner is produced by a polymerization method. An image forming method, which is a manufactured toner. 2. The image forming method according to claim 1, wherein the chromatic color toner particles have a shape factor SF-1 of 100 to 140. 3. The chromatic color toner has a weight average particle diameter of 1 to 9 μm.
The image forming method described in 1 .. 4. The image forming method according to claim 1, wherein the chromatic color toner particles contain a metal salt or a metal complex of an aromatic carboxylic acid derivative. 5. The chromatic color toner particles have a softening point of 4
The image forming method according to any one of claims 1 to 4, further comprising a wax having a temperature of 0 to 90 ° C. 6. The chromatic color toner particles are formed by polymerizing a monomer composition containing a polymerizable monomer, according to any one of claims 1 to 5. The image forming method described. 7. The image forming method according to claim 1, wherein the latent image carrier is a photoconductor for electrophotography. 8. The latent image carrier has a cylindrical shape,
The developing device has a toner carrier having a cylindrical shape for carrying and carrying the chromatic color toner and the chromatic color toner, and in the developing step, the chromatic color is carried on the toner carrier. While forming a toner layer of color toner and rotating the latent image carrier having the cylindrical shape and the toner carrier having the cylindrical shape with respect to each other, the toner carrier having the cylindrical shape passes through the toner layer. Contact development is performed to develop the electrostatic latent image by bringing the toner layer into contact with the surface of the latent image carrier having the cylindrical shape while being substantially in contact with the latent image carrier having the cylindrical shape. The image forming method according to any one of claims 1 to 7, wherein: 9. A latent image carrier in the advancing direction of the latent image carrier in the order of (I) the primary charging of the latent image carrier in the charging step, and (II) the latent image carrier in the developing step. A developing unit for developing the held electrostatic latent image by the developing device, and (III) the chromatic color toner image formed on the latent image holding member in the transfer step on the recording material. Cleaning means for locating the transferring portion for transferring, and for removing the chromatic color toner remaining on the latent image carrier after the transferring step by contacting with the surface of the latent image carrier. Is not present between the transfer section and the charging section and between the charging section and the developing section, and the chromatic color toner remaining on the latent image carrier after the transfer step is collected. 2. The developing device also serves as the developing step. 8. The image forming method described in any one of 7 to 7. 10. A charging unit for primary charging the latent image holding member in the charging step in the order of travel of the latent image holding member, and (II) to the latent image holding member in the developing step. A developing unit that develops the held electrostatic latent image by the developing device, and (III) the chromatic color toner image formed on the latent image carrier in the transfer step on the recording material. The transfer portion that is transferring is located, the latent image carrier has a cylindrical shape, and the developing device is
A chromatic color toner and a toner carrier having a cylindrical shape for carrying and carrying the chromatic color toner, and a toner layer of the chromatic color toner on the toner carrier in a developing step. And the toner carrier having the cylindrical shape and the toner carrier having the cylindrical shape are rotated with respect to each other, the toner carrier having the cylindrical shape is substantially interposed between the toner layer and the toner layer. The toner layer is brought into contact with the surface of the latent image carrier having a cylindrical shape in a state of being in contact with the latent image carrier having a shape, and contact development for developing the electrostatic latent image is performed. Cleaning means for contacting and removing the chromatic color toner remaining on the latent image carrier after the process from the surface of the latent image carrier is provided between the transfer part and the charging part and the charging part. Between the development section and the development section 10. The developing device also serves to collect the chromatic color toner remaining on the latent image carrier after the transfer step, in the developing step, as well. An image forming method according to claim 1.