JPH07271102A - Electrostatic charge image developer and multicolor image forming method - Google Patents

Abstract

PURPOSE:To prevent contamination in the background or scattering of a carrier on a copy even when copies are continuously produced for a long time. CONSTITUTION:This electrostatic charge image developer consists of a color toner and a magnetic powder dispersion-type carrier having magnetic particles dispersed in a binder resin. The surface of the carrier contains >=0.1wt.% conductive inorg. oxide fine particles. The color toner contains >=1.5wt.% compd. expressed by formula as a charge controlling agent and the surface of the toner particle contains >=2.0wt.% inorg. oxide fine particles. In formula, R1-R4 are alkyl groups or benzyl groups of 1-18 carbon number and X<-> is naphthalene sulfone anion. This electrostatic charge image developer is suitable to be used for one-path multicolor image forming method including a process to form a latent image on a latent image holder and a process to develop the latent image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component developer for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like, and a multicolor image forming method using the same. .

[0002]

2. Description of the Related Art A two-component developer composed of a toner and a carrier is often used as a developer for developing an electrostatic image in electrophotography and the like. Various carriers are known as two-component developers, and representative examples thereof include a conductive carrier such as iron oxide powder and a coat-type insulating carrier. Although the conductive carrier is excellent in solid developability, it is inferior in fine line reproducibility, and has a defect that the charge amount is remarkably reduced due to fusing and adhesion of the toner to the carrier surface. On the other hand, the coated insulating carrier is
Although it is excellent in terms of life, reproducibility of fine lines, etc., it has a drawback of poor solid reproducibility. For the purpose of improving these drawbacks, a magnetic powder dispersion type carrier having a small particle size in which magnetic powder fine particles are dispersed in a binder resin, that is, a so-called microtoning carrier has been proposed and put into practical use. Such a magnetic powder-dispersed carrier has a low true specific gravity, high insulating properties, and a small particle size.
Compared with the conventional carrier, it is dense and uniform, has good density reproducibility, has no noise such as brush eyes due to a magnetic brush, and has the advantage of improving image quality. On the other hand, regarding the toner, various inorganic and organic fine powders are used as an external additive in order to improve the fluidity, anti-caking property, stability, charging property, cleaning property, etc. and to have process compatibility. Is known to be added, and it has been proposed to use, for example, silica, titanium oxide, aluminum oxide, tin oxide or the like. Further, a developer in which these toners are combined with the magnetic powder dispersion type carrier is also proposed. For example, in JP-A-60-136775, a magnetic powder dispersion type carrier and a titanium oxide / silica fine powder are adhered. A developer made of toner is also disclosed in
Japanese Patent Laid-Open No. 1-9661 describes a developer composed of a toner to which a magnetic powder dispersion type carrier and silica fine powder are adhered.

[0003]

When a developer comprising a magnetic powder-dispersed carrier and color toner is used in a copying machine, a printer, etc., if the charge amount of the developer is high, the carrier adheres to the photoreceptor. However, when the charge amount is low, there is a problem in that the background image stains occur in the copy image when it is left under high temperature and high humidity. In recent years, a one-pass two-color system has been proposed which develops and transfers two colors of black and color while the photosensitive drum makes one rotation. The developer used in this system is especially the first development and the first development. When there is no recharging mechanism between two developments, high developability at low potential is required. In order to meet the requirement, the charge amount of the developer has to be lowered to some extent, and therefore, there arises a problem that the background portion is smeared on the copied image as described above. It is assumed that this is due to the following reasons. That is, the magnetic powder-dispersed carrier has a low magnetic force, is used in a relatively small particle size, has a smaller specific gravity than an ordinary carrier, and has an irregular shape. Poor fluidity, the probability of contact between the toner and carrier is significantly reduced, frictional contact with the carrier is limited, and toner / carrier charge exchange is significantly reduced. As a result, after discharge under high temperature and high humidity, frictional electrification between the toner particles is promoted, toner of opposite polarity and low-charged toner are generated, and the background portion of the image is stained. In particular, the above phenomenon is remarkable when a color toner that cannot use carbon black is used as a colorant. This phenomenon is presumed to be due to the inferior charge exchange property of the colorant for color compared to carbon black. In order to improve the above-mentioned drawbacks, it is also possible to add excessive inorganic oxide fine particles to the toner in order to improve the fluidity of the developer and the initial charge exchange property. There is a problem in that long-term high reliability is significantly impaired in that the absolute value of the quantity is lowered.

The present invention has been made to solve the above-mentioned problems in the prior art. That is, the object of the present invention is to use a long-life magnetic powder-dispersed carrier that does not cause background stains on images when left under high temperature and high humidity, both initially and after copying a large number of sheets. It is to provide a two-component developer for a charge image. Another object of the present invention is to provide a long-life two-component developer for electrostatic charge images in which carrier does not migrate to the photoconductor due to increased charge even if mechanical stress is applied in the developing device. Still another object of the present invention is to provide a multicolor image forming method for forming an excellent image quality by a one-pass multicolor color developing system.

[0005]

The developer for electrostatic charge images of the present invention comprises a magnetic powder-dispersed carrier in which magnetic powder is dispersed in a binder resin, and a color toner. The color toner contains 0.1% by weight or more and 1.0% by weight or less of conductive inorganic oxide fine particles, and the color toner contains a compound represented by the following formula (I) as a charge control agent: 1.
7. 5% by weight or more and 6.0% by weight or less, and 2.0% by weight or more of inorganic oxide fine particles on the surface of the toner particles, 8.
It is characterized by containing 0% by weight or less.

[Chemical 2] (In the formula, R ₁ to R ₄ each represent an alkyl group having 1 to 18 carbon atoms or a benzyl group, and X ⁻ represents a naphthalene sulfone anion or a substituted naphthalene sulfone anion.)

Further, the multicolor image forming method of the present invention comprises a step of forming a latent image on a latent image carrier and a step of developing the latent image with a developer, and at least As a developer in a developing device after the second development, a magnetic powder-dispersed carrier, in which magnetic powder is dispersed in a binder resin, and a color toner are used. The color toner contains 1.5% by weight or more and 1.0% by weight or less, and the color toner contains 1.5% by weight or more of a compound represented by the following formula (I) as a charge control agent
It is characterized in that the content of the toner is 6.0% by weight or less and the content of the inorganic oxide fine particles is 2.0% by weight or more and 8.0% by weight or less on the surface of the toner particles.

The present invention will be described in detail below. The toner in the developer for electrostatic charge images of the present invention is composed mainly of a binder resin and a colorant. Examples of the binder resin used include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate. , Methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate,
Α-, such as dodecyl methacrylate and phenyl methacrylate
Homopolymers or copolymers of vinyl ethers such as methylene aliphatic monocarboxylic acid esters, vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. Specific examples of the binder resin include polystyrene, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, and polyethylene. , Polypropylene, etc. can be mentioned. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, wax and the like can be mentioned.

As the colorant to be used, any one can be used as long as it is usually used for color toners, and one or more kinds out of organic dyes, organic pigments and inorganic pigments can be used. Can be appropriately selected and used. For example, aniline blue, calcoil blue, chrome yellow, ultramarine blue,
DuPont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Copper Phthalocyanine, Malachite Green Oxalate, Rose Bengal, C.I. I. Pigment
Red 48: 1, C.I. I. Pigment Red 122,
C. I. Pigment Red 57: 1, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 1
2, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 can be used.
In the present invention, the content of the colorant is 5 to 15% by weight.
It is preferable to use in the range of.

As the charge control agent contained in the toner, those represented by the general formula (I) are used.
Specifically, the following can be illustrated.

[Chemical 3]

[0010]

[Chemical 4]

[0011]

[Chemical 5]

The amount of the charge control agent added to the toner is
It is necessary to be 1.5% by weight or more, and preferably 2.0 to 6.0% by weight. If the addition amount is less than 1.5% by weight, the copy background portion will be stained after being left under high humidity. Also, 6.0% by weight
If it exceeds, there may be a problem in charge stability. These are used as one kind or as a mixture of two or more kinds, but other quaternary ammonium salts or chromium-containing dyes,
You may use together a salicylic acid metal complex compound etc.

The toner contains low molecular weight propylene,
Other known components such as an anti-offset agent such as low molecular weight polyethylene and wax can be added. Particularly, low molecular weight polypropylene having a weight average molecular weight of 500 to 5000 is preferable. In order to produce the toner of the present invention, the above toner materials may be mixed using a Banbury mixer, a kneader coater, a CM mixer, an extruder, etc., melt-kneaded, pulverized and classified, and the average particle diameter is 30 μm. In the following, it is particularly preferable that the particle size is 3 to 20 μm.

The inorganic oxide fine particles adhered to the surface of the toner particles include TiO ₂ , MgO, Al ₂ O ₃ and S.
Fine particles such as nO ₂ , SiO ₂ and ZnO can be used. The surface of these inorganic oxide fine particles may be treated with an organic substance. The particle size of the inorganic oxide fine particles is preferably in the range of 3 μm or less. Particularly, the range of 60 nm or less is preferable. The inorganic oxide fine particles can be adhered to the surface of the toner particles by adding the inorganic oxide fine particles to the toner particles and mixing them with, for example, a Henschel mixer. The compounding amount at that time is 2.0% by weight based on the total amount of the toner.
As described above, it is necessary to be 8.0% by weight or less, preferably 3.0% by weight or more and 6.0% by weight or less. If the blending amount is less than 2.0% by weight, the effect of addition becomes insufficient. On the other hand, if it exceeds 8.0% by weight, the charging property tends to decrease.

The carrier in the present invention is of a magnetic powder dispersion type, and is mainly composed of resin and magnetic powder. As the resin, those exemplified as the binder resin for the toner particles can be used. Moreover, as the magnetic powder, fine particles of a commonly used ferromagnetic material can be used, and specific examples thereof include triiron tetraoxide, γ-iron sesquioxide, various ferrites, chromium oxide, and various fine metal powders. To be Further, a charge control agent or the like can be contained if necessary. The amount of these magnetic powders to be blended is about 30 to 95% by weight, preferably 45 to 9% by weight based on the whole carrier.
It is in the range of 0% by weight. The carrier is kneaded with the above components,
It can be prepared by crushing and classifying, or can be prepared by dissolving the above components in a suitable solvent or liquefying by heating and spray drying or the like. The average particle size of the carrier is generally about 20-40.
It is in the range of 0 μm, preferably in the range of 30 to 100 μm.

In the present invention, it is necessary that conductive inorganic oxide fine particles are attached to the surface of the carrier. As the conductive inorganic oxide fine particles, for example, T
Conductive fine powders such as iO ₂ , SnO ₂ , Al ₂ O ₃ , MgO and ZnO can be mentioned. To attach these fine powders, for example, a V-type blender, a Henschel mixer, or the like may be used for mixing. The amount of the fine powder of conductive inorganic oxide attached is required to be 0.1% by weight or more and 1% by weight or less, preferably 0.2% by weight to 1.0% by weight, based on the total amount of the carrier. Is the range. Particularly preferably, it is in the range of 0.2% by weight to 0.6% by weight. When the adhered amount of the conductive inorganic oxide fine powder is lower than 0.1% by weight, the copy background portion is stained after being left under high humidity. On the other hand, if it exceeds 1.0% by weight, the charging property tends to decrease.

The electrostatic latent image developer of the present invention is suitable for developing an electrostatic latent image having a low potential contrast of about 100 to 400V. Therefore, it can be used for a one-pass color developing method having a step of developing using a plurality of developing devices that form toner images of two or more colors during one rotation of the photosensitive drum. At that time, it is preferable to supply at least the developing device after the second development.

FIG. 1 is a schematic configuration diagram of an example of a multicolor image forming apparatus adopting the one-pass color developing system used in the present invention. In the figure, reference numeral 1 is a photosensitive drum, around which a charging device 2, a first exposing device 3, a first developing device 4, a second exposing device 5, and a second developing device 6 are sequentially provided. Further, a transfer charger 7, a static eliminator 8, a cleaner 9 and a static elimination lamp 10 are provided. Note that 11 is a recording paper. The photoconductor drum 1 is rotating in the direction of the arrow. First, the charging device 2 uniformly charges the photosensitive layer on the surface of the photosensitive drum 1. Next, the first exposure device 3 irradiates light according to the image information corresponding to the first color to form an electrostatic latent image corresponding to the first color on the photoconductor. Any exposure device can be selected. Then, the first developing device 4 supplies toner corresponding to the first color to the photosensitive layer having the first electrostatic latent image formed by the first exposing device to visualize the toner. At this time, the developing bias is selected depending on whether regular development or reverse development is performed.

Subsequently, the second exposure device 5 irradiates light according to the image information corresponding to the second color to form an electrostatic latent image corresponding to the second color on the photosensitive layer. An arbitrary second exposure device is used. Then, the second developing device 6 supplies the toner corresponding to the second color to the photosensitive layer having the second electrostatic latent image formed by the second exposing device to visualize the photosensitive layer. At this time, the developing bias can also be arbitrarily selected. The first toner image and the second toner image formed on the photosensitive layer of the photosensitive drum are transferred to the recording paper 11 by the transfer charger 7, but may be transferred using a means other than electrostatic transfer. . The recording paper is then fixed by a fixing unit (not shown).
Further, the photoconductor that has passed through the transfer portion is cleaned by the static eliminator 8, the cleaner 9 and the static elimination lamp 10 for reuse.

The first and second exposing means are composed of a light illuminating means, a document scanning means and an image forming optical system, which are used in an ordinary copying machine, but can be optically modulated according to image information. An optical writing device such as a laser writing device, a liquid crystal light valve including a uniform light source and a liquid crystal micro shutter, an LED array, an optical fiber, or the like can be used according to the purpose. In some cases, a second charging unit may be provided before the second exposure unit.

[0021]

When a magnetic component dispersion type carrier that does not adhere to the conductive inorganic oxide fine powder is used, poor charge exchange properties, charge leakage when the toner is left under high humidity, and rise of charge are combined, After being left under high humidity, copy background stains occur. This phenomenon is initially improved by preliminarily depositing the conductive inorganic oxide fine powder on the carrier, but when left under high humidity after long-term continuous copying, the background stains are still on the copy. There is a problem that occurs. The cause is presumed as follows. The desorption of the conductive inorganic oxide fine powder on the carrier surface is observed from the electron micrographs of the carrier surface after continuous copying, and the conductive inorganic oxide fine powder occupies the carrier from the fluorescent X-ray analysis. It is considered that this is because the conductive inorganic oxide fine powder on the carrier surface is desorbed during continuous copying and then is released or migrates to the toner surface and the charge exchange property is lowered. As a result of studies by the present inventors, this phenomenon depends on the type and amount of the charge control agent contained in the toner, and the more the charge control agent represented by the above formula (I) is contained, the greater the degree. It turned out to be improved. However, as the amount of the charge control agent increases, the charge amount also increases, and the mechanical stress in the developing device further increases the charge amount, causing the carrier to adhere to the photoreceptor. However, as in the present invention, when the content of the conductive fine powder on the carrier surface is set to 0.1% by weight or more and the addition amount of the inorganic oxide fine particles to the toner particle surface is set to 2.0% by weight or more. The problem as described above does not occur at all. Therefore, in the developer for electrostatic image of the present invention, there is no background stain of the copy image even after standing under high temperature and high humidity, and it is possible to prolong the life of the developer without background stain after long-term continuous copying. Of.

[0022]

The present invention will be described in more detail with reference to the following examples. However, the present invention is in no way limited by these examples. In the following description, all “parts” represent “parts by weight”.

Toner Production Example 1 Toner Production Example 1 Styrene-butyl acrylate (80/20) copolymer 100 parts (Mw: 250,000, Mn: 5000) Low molecular weight polypropylene (Viscole 660P, 5 parts Sanyo Kasei Co., Ltd.) ) Charge control agent: Exemplified compound No. 3 3 parts Copper phthalocyanine pigment (CI Pigment Blue 15: 3) 7 parts The above components were melt-kneaded with a Banbury mixer.
After cooling, it was finely pulverized by a jet mill, and the finely pulverized product was classified by a classifier to obtain toner particles having an average particle diameter d50 of 11 μm. To 100 parts of the toner particles, 4 parts of TiO ₂ fine particles having an average volume diameter of 25 mμ were added and dispersed and mixed by using a Henschel mixer to form TiO _{2 on the} surface.
A toner having fine particles attached was prepared. Toner Production Example 2 In the toner production example 1, instead of 7 parts of the copper phthalocyanine pigment in the toner, a copper phthalocyanine pigment (C.I.
Pigment Blue 15: 3) 2 parts and C.I. I. Pigment Yellow 97 was used in the same manner as in Toner Production Example 1 except that 5 parts of Pigment Yellow 97 was used. Toner Production Example 3 In Toner Production Example 1, as the charge control agent, Exemplified Compound No. 3 parts to 3 parts to 2 parts, and 4 parts of TiO ₂ fine particles
A toner was prepared in the same manner as in Toner Production Example 1 except that the parts were changed to 3 parts. Toner Production Example 4 In Toner Production Example 1, as the charge control agent, Exemplified Compound No. A toner was produced in the same manner as in Toner Production Example 1 except that 3 parts of 3 were changed to 0.8 part and 4 parts of TiO ₂ fine particles were changed to 2 parts. Toner Production Example 5 In Toner Production Example 1, 4 parts of TiO ₂ fine particles were mixed with 1.
A toner was produced in the same manner as in Toner Production Example 1 except that the amount was changed to 5 parts. Toner Production Example 6 In Toner Production Example 1, as the charge control agent, Exemplified Compound No. 3 is exemplified compound No. A toner was produced in the same manner as in Toner Production Example 1 except that the toner was changed to 1.

(Production Example of Carrier) Production Example 1 of Carrier Styrene-butyl methacrylate (80/20) copolymer 30 parts (Tg: 80 ° C., Mw: 100,000) Magnetite (EPT-1000, manufactured by Toda Kogyo Co., Ltd.) ) 100 parts The above components were melt-kneaded with a pressure kneader and further pulverized and dispersed using a turbo mill and a classifier to obtain an untreated carrier having an average volume diameter d50 of 50 μm. Carrier Production Example 2 100 parts of the carrier produced in Carrier Production Example 1 had a particle size of 25 mμ.
Fine particles of TiO ₂ (volume resistivity: 2.0 × 10 ⁷ Ω · c
m) was added to 0.4 part and stirred with a V blender for 20 minutes,
A carrier having TiO ₂ fine particles attached thereto was obtained. Carrier Production Example 3 A carrier prepared by adhering TiO ₂ fine particles was prepared in the same manner as in Carrier Production Example 2 except that 0.4 parts of TiO ₂ fine particles were changed to 0.07 parts by weight in Carrier Production Example 2. Obtained.

Examples 1 to 4 and Comparative Examples 1 to 4 7 parts of the above toner was mixed with 100 parts of the above carrier in a V type blender to prepare a dry developer. The carrier and toner combinations used were as shown in Table 1.

The following experiments were carried out on the dry developers of Examples 1 to 4 and Comparative Examples 1 to 4 above. (1) Initial background stain After the developer is prepared, it is left in a thermo-hygrostat at 35 ° C. and 85% RH for 4 days and taken out, and then a copying machine (Able 1
301α, manufactured by Fuji Xerox Co., Ltd.), the copying operation was performed, and the background stain of the second copy was evaluated. The background stain was evaluated on a scale of 1 to 10. Grade 1 means a completely clean state, and 4 means an upper limit level that is acceptable. (2) Background stain after continuous copying In the same manner as above, the developer left to stand in a thermo-hygrostat at 35 ° C. and 85% RH for 4 days was exposed to the environment of 28 ° C. and 85% RH.
Copier (Able 1301α, made by Fuji Xerox Co., Ltd.)
Into the second developing device of No. 3, a continuous copying operation of 5,000 sheets per day was performed up to a total of 40,000 sheets, and the background stain of the copy was traced and evaluated. (3) MCO (Scattering of carrier onto copy) After preparing a developer, the developer is put into a second developing device and kept at 10 ° C. for 3 minutes.
After leaving it in an environment room of 0% RH and making 1000 continuous copies in the same environment, carrier scattering (MCO) on the copy image was evaluated. MCO was evaluated on a scale of 5 from 1 to 5, and Grade 1 means a state in which no generation of MCO was observed.

[0027]

[Table 1] As is clear from the results in Table 1, the developers of Examples 1 to 4 have excellent effects on the initial background stain and the background stain after continuous copying.

Next, specific conditions will be shown when the electrostatic image developer of the present invention is used in the multicolor image forming apparatus shown in FIG. In carrying out the present invention, a black developer for Fuji Xerox FX5039 is supplied as a developer to the first developing device, and a blue developer described in Example 1 of the present invention is supplied to the second developing device. Then, color image recording was performed. First, the surface of the photosensitive drum 1 having a photosensitive layer made of an organic photoconductive material is uniformly charged to −750 V by the charger 2, and then reverse exposure is performed by the He—Ne laser light from the first exposure device 3. Then, a first electrostatic latent image having an exposed portion potential of −120 V and a non-exposed portion potential of −750 V was formed on the surface of the photosensitive drum. Then, a bias voltage of -600 V was applied, and development was performed by the first developing device 4 to form a black first toner image. Subsequently, a positive image exposure is performed by the second exposure device 5, and the exposed portion is -200V and the non-exposed portion is -750V.
Electrostatic latent image is formed, and the developing bias voltage is set to -4.
The development was performed by the second developing device 6 while setting it to 00V, and a blue toner image was formed. As a result, two color toner images of blue and black were formed on the photosensitive drum. This toner image was transferred onto the recording paper 11 by the transfer charger 7 and fixed by an appropriate fixing means (not shown). The photoconductor drum that passed through the transfer portion was cleaned by a static eliminator, a cleaner and a static eliminator lamp for reuse. This operation was repeated 5,000 times. As a result, a clear image without fog, mixed color fog, and image disturbance was obtained.

[0029]

Since the electrostatic latent image developer of the present invention has the above-mentioned constitution, when it is left under high temperature and high humidity, background stain is generated both initially and after long-term continuous copying. In addition, the carrier is not scattered on the copy. Furthermore, since the developing property at low potential is excellent, in the multi-color image forming method adopting the one-pass multi-color developing method for obtaining toner images of two or more colors during one rotation of the photosensitive drum, It is suitable for use as a developer and can prevent color mixture fog and image distortion.
A stable multicolor image can be obtained over a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus used in the present invention.

[Explanation of symbols]

1 ... Photosensitive drum, 2 ... Charging device, 3 ... First exposure device, 4 ...
1st developing device, 5 ... 2nd exposing device, 6 ... 2nd developing device, 7 ... Transfer charging device, 8 ... Static eliminator, 9 ... Cleaner, 10 ... Static elimination lamp, 11 ... Recording paper.

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Claims (2)

[Claims] 1. A developer for electrostatic charge images comprising a magnetic powder-dispersed carrier in which magnetic powder is dispersed in a binder resin, and a color toner, wherein conductive inorganic oxide fine particles are formed on the surface of the carrier. 1 weight% or more and 1.0 weight% or less is contained, and the color toner has the following formula (I) as a charge control agent.
1.5% by weight or more and 6.0% by weight or less, and 2.0% by weight or more and 8.0% by weight or less of inorganic oxide fine particles on the surface of the toner particles. A developer for electrostatic charge images, characterized by: [Chemical 1] (In the formula, R ₁ to R ₄ each represent an alkyl group having 1 to 18 carbon atoms or a benzyl group, and X ⁻ represents a naphthalene sulfone anion or a substituted naphthalene sulfone anion.) 2. A multicolor image forming method comprising a step of forming a latent image on a latent image carrier and a step of developing the latent image with a developer, wherein at least development in a developing device after the second development is performed. A multicolor image forming method, wherein the developer for electrostatic charge image according to claim 1 is used as an agent.