JP3997670B2 - Image forming method - Google Patents

Description

【００７８】
表１の結果から、中間転写体を経由する画像形成方法において、実施例１〜５の本発明の画像形成方法では、トナー中の着色剤量、トナー形状、及びべた画像トナー重量を特定の数値範囲に規定することにより、画質特性のバランスにおいて極めて優れた特性が得られることがわかる。この場合、トナー粒子径をより小径化にすることにより、更に優れた画質特性が得られることがわかる。
一方、比較例に示した様に、単にトナー粒子径を小径化し、その粒子径分布を制限し、狭分布とすることのみでは、細線再現性、階調再現性、ハイライト部粒状性においては改善の傾向は認められるものの、十分な画質特性を得ることはできない。また、比較例３においては、十分な画像濃度を達成するために、べた画像トナー重量を増加させると、画像濃度は向上するものの、細線再現性が極めて不十分なものとなる。
【００７９】
（実施例６）
［マゼンタトナーの作製］
−顔料分散液２−
赤色顔料 ・・・・・・・・・・・・・・・・・・・・・・・・・ ５０部
（大日本精化（株）製、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２）
アニオン性界面活性剤（第一工業製薬社製、ネオゲンＲ） ・・・・ ５部
イオン交換水 ・・・・・・・・・・・・・・・・・・・・・・ ２００部
上記成分をホモジナイザー（ＬＫＡ社製、ウルトラタラックスＴ５０）で１０分間分散し、更に超音波ホモジナイザーで分散し、顔料の体積平均粒子径（Ｄ₅₀）が１５３ｎｍの赤色顔料分散液２を得た。
【００８０】
実施例１において、顔料分散液１を１８．８部添加する代わりに、顔料分散液２を３７．６部添加した以外は、実施例１と同様にして、マゼンタトナーを作製した。得られたマゼンタトナーは、体積平均粒子径６．４μｍ、ＧＳＤｖ１．２０、中心形状係数１１５、ＳＦ１２５以上の粒子の個数％が５％、ＳＦ１３０以上の粒子の個数％が０．５％であった。このトナー粒子の酸価をＫＯＨ滴定法により求めたところ、１３．０ｍｇＫＯＨ／ｇであった。得られたマゼンタトナーを用いて、実施例１と同様にして現像剤を製造した。
【００８１】
［イエロートナーの作製］
−顔料分散液３−
黄色顔料 ・・・・・・・・・・・・・・・・・・・・・・・・・ ５０部
（ヘキスト社製、Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １８０）
アニオン性界面活性剤（第一工業製薬社製、ネオゲンＲ） ・・・・ ５部
イオン交換水 ・・・・・・・・・・・・・・・・・・・・・・ ２００部
上記成分をホモジナイザー（ＬＫＡ社製、ウルトラタラックスＴ５０）で１０分間分散し、更に超音波ホモジナイザーで分散し、顔料の体積平均粒子径（Ｄ₅₀）が１５１ｎｍの黄色顔料分散液３を得た。
【００８２】
実施例１において、顔料分散液１を１８．８部添加する代わりに、顔料分散液３を３７．６部添加した以外は、実施例１と同様にして、イエロートナーを作製した。得られたイエロートナーは、体積平均粒子径６．４μｍ、ＧＳＤｖ１．１９、中心形状係数１１６、ＳＦ１２５以上の粒子の個数％が７％、ＳＦ１３０以上の粒子の個数％が０．７％であった。このトナー粒子の酸価をＫＯＨ滴定法により求めたところ、１２．９ｍｇＫＯＨ／ｇであった。得られたイエロートナーを用いて、実施例１と同様にして現像剤を製造した。
【００８３】
［画像形成］
上記で得られたマゼンタ現像剤及びイエロー現像剤、更に実施例１で得られたシアン現像剤を用い、それぞれ下記表２のように、べた画像トナー重量（ＴＭＡ）を調整し、３色重ね合わせたプロセスブラック画像を形成した以外は、実施例１と同様にして画像形成を行い、同様の画質評価を行った。結果を下記表２に示す。
【００８４】
【表２】

【００８５】
表２の結果から、中間転写体を経由する本発明の画像形成方法では、画質特性に極めて優れた画像が得られることがわかる。
【００８６】
【発明の効果】
本発明によれば、中間転写体を経由し画像形成を行う画像形成方法において、優れた画質特性（細線再現性、階調再現性、画像再現性、トナーの飛び散り防止）を有し、信頼性の高い画像を形成する方法を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method in which an electrostatic latent image is developed and transferred to an intermediate transfer member in an electrophotographic method or an electrostatic recording method, and an image is formed by fixing such as heating.
[0002]
[Prior art]
Methods for visualizing image information through an electrostatic latent image, such as electrophotography, are currently used in various fields. In this method, in electrophotography, an electrostatic latent image is formed on a photoreceptor in a charging / exposure process, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer using a magnetic toner or a nonmagnetic toner alone. The toner is usually produced by a kneading and pulverizing method in which a thermoplastic resin is melt-kneaded together with a release agent such as a pigment, a charge control agent, and a wax, cooled, finely pulverized, and further classified. In this toner, in order to improve fluidity and cleaning properties, inorganic fine particles or organic fine particles may be added to the surface of the toner particles as necessary.
[0003]
On the other hand, in recent years, with the advancement of an advanced information society, there has been an increasing demand for providing higher quality images of information documents constructed by various methods. It is being advanced. This requirement is not an exception even in image forming methods using electrophotography, and in particular in electrophotography, in order to realize a higher-definition image in color image formation, toner diameter reduction and sharp particle size distribution Achievement is demanded.
[0004]
For example, in a digital full-color copying machine or printer, a color image original is color-separated with B (blue), R (red), and G (green) filters, and then a dot diameter of 20 to 70 μm corresponding to the original original is used. The latent image is developed by subtractive color mixing using Y (yellow), M (magenta), C (cyan), and Bk (black) developers. In this method, it is necessary to transfer a large amount of developer as compared with a conventional black-and-white machine, and it is necessary to cope with a dot having a smaller diameter. It is increasingly important to ensure the properties, sharpness of particle size distribution, and toner strength. In consideration of speeding up and energy saving of these machines, extremely low temperature fixability is required. From these facts, there is a demand for a toner having a sharp particle size distribution and a small particle size.
[0005]
Further, from the viewpoint of increasing the resolution such as fine line reproducibility and gradation reproducibility, an image forming method via an intermediate transfer member has been used in recent years especially in electrophotographic image formation for the purpose of full color image formation. . This is because color misregistration hardly occurs when the toner images of the respective colors are superimposed, and various papers (for example, envelopes, postcards, label papers, etc., thin paper (40 g / m ² Paper) to thick paper (200g / m ² It is used for the purpose of reducing the quality variation of the image characteristics due to the thickness of the final image forming material, etc., and high-resolution high-speed image formation.
However, in image formation using these intermediate transfer members, if the toner particle diameter described above is simply reduced, the number of electrostatic toner transfers until the final image is increased, or the particle size is reduced. It is difficult to obtain high-quality image characteristics by simply reducing the particle size, such as a decrease in transfer efficiency due to an increase in the powder adhesion force accompanying the transfer, and various image quality defects due to transfer defects.
[0006]
On the other hand, for the purpose of realizing high image quality characteristics in reducing the particle size of these toners, the possibility of various particle size distribution limitations has been proposed. For example, in JP-A-5-107809 and JP-A-6-75430, the particle size distribution of the toner is limited, in particular, the central particle size is limited to the number% of the toner having a particle size of 4 μm or less, or more than 8 μm. Although attempts have been made to improve the image quality of small toners by limiting the particle size distribution of the toner, such as the number of toners, etc., it is possible to reduce the powder adhesion force by contacting large areas of irregularly shaped toner with these simple particle size distribution restrictions. Is not achieved sufficiently, and it is difficult to obtain high-quality images, especially in the electrophotographic image forming method with a large number of transfers via an intermediate transfer member, and it is necessary to reduce the powder adhesion by controlling the shape of the toner. It becomes.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention has excellent image quality characteristics (fine line reproducibility, gradation reproducibility, image reproducibility, prevention of toner scattering) and reliability in an image forming method for forming an image via an intermediate transfer member. An object of the present invention is to provide a method for forming an image having a high image quality.
[0008]
[Means for Solving the Problems]
As a result of intensive studies, the inventors have controlled the content of the colorant in the toner, the volume average particle size and particle size distribution, the central shape factor and distribution thereof, and the toner weight in a solid image to a specific value. Thus, the present inventors have found that the above problems can be solved, and have completed the present invention.
Means for solving the above problems are as follows. That is,
<1> A latent image forming step of forming an electrostatic latent image on an electrophotographic photosensitive member, a developing step of developing the electrostatic latent image with toner to form a toner image, and the toner image on an intermediate transfer member In an image forming method including a first transfer step of transferring, and a second transfer step of transferring the toner image on the intermediate transfer member to a transfer material,
The toner contains a colorant and a binder resin, the content of the colorant is 2.5% by volume or more in the toner, and the volume average particle size distribution GSDv in the toner is 1.26 or less. The volume average particle diameter is 2 to 6.5 μm, the central shape factor is 120 or less, and the number% of particles having a shape factor of 125 or more is 6% or more 10% or less, and the number% of particles having a shape factor of 130 or more is 0.3% or more The toner weight when forming a solid image of 1% or less and an area ratio of 100% is 1 cm per color. ² The image forming method is characterized by being 0.1 to 0.5 mg per unit.
[0009]
Furthermore, the means for solving the above-mentioned problems are preferably the following modes.
<2> The image forming method according to <1>, wherein the toner contains a release agent.
<3> An inorganic metal salt having a bivalent or higher charge, wherein the toner is a mixture of at least one resin fine particle dispersion and at least one colorant dispersion, and is dissolved in a dispersion medium of the mixture. The image forming method according to <1>, wherein the aggregate is formed by adding to the liquid mixture and then heating to a temperature equal to or higher than the glass transition point of the resin to fuse the aggregate. is there.
<4> The image forming method according to <3>, wherein the volume average particle diameter of the resin fine particles in the resin fine particle dispersion and the colorant in the colorant dispersion is 1 μm or less.
<5> The image forming method according to <3> or <4>, wherein at least one type of release agent fine particle dispersion is added to the mixed solution.
<6> The image forming method according to any one of <3> to <5>, wherein the inorganic metal salt includes at least an inorganic metal salt of Al.
<7> The image forming method according to any one of <3> to <6>, wherein the inorganic metal salt includes a polymer of an inorganic metal salt.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The image forming method of the present invention includes a latent image forming step, a developing step, a first transfer step, and a second transfer process. About And other steps such as a fixing step as necessary. The present invention is an image forming method using an intermediate transfer member. However, according to the present invention, the problems described in the above-mentioned conventional techniques, that is, problems such as a decrease in transfer efficiency and various image quality defects due to transfer defects. Can be solved.
[0011]
[Development process]
The developing step is a step of developing the electrostatic latent image on the electrophotographic photosensitive member with toner to form a toner image. In the developing step, a known developing device having a function of attaching the toner to the electrophotographic photosensitive member using a brush, a roller or the like can be used.
In the image forming method of the present invention, the toner used in the development step contains a colorant and a binder resin, and the content of the colorant is 2.5% by volume or more in the toner. The volume average particle size distribution GSDv is 1.26 or less, the volume average particle size is 2 to 6.5 μm, the central shape factor is 120 or less, and the number% of particles having a shape factor of 125 or more is 6% or more 10% or less, and the number% of particles having a shape factor of 130 or more is 0.3% or more The toner weight when forming a solid image of 1% or less and an area ratio of 100% is 1 cm per color. ² It is characterized by 0.1 to 0.5 mg per unit.
[0012]
Thus, the content of the colorant in the toner, the toner particle size distribution, the toner particle size, its shape distribution, and the solid image toner weight (mg / cm ² ), Excellent image quality characteristics (thin line reproducibility, gradation reproducibility, image reproducibility, prevention of toner scattering) can be obtained, and a highly reliable image, particularly a color image, can be provided.
[0013]
(toner)
The toner contains at least a colorant and a binder resin, preferably contains an inorganic metal salt, and further contains other components such as a release agent as required.
[0014]
The content of the colorant is 2.5% by volume or more in the toner, preferably 3.5 to 8.0% by volume. When the content is less than 2.5% by volume, it is difficult to obtain a sufficient image density.
[0015]
The volume average particle size distribution GSDv in the toner is 1.26 or less, preferably 1.25 or less. When the GSDv exceeds 1.26, fine line reproducibility deteriorates.
The volume average particle diameter of the toner is 2.0 to 6.5 μm, preferably 3.0 to 6.0 μm. When the volume average particle diameter exceeds 6.5 μm, the fine line reproducibility and gradation cannot be improved, and the smoothness of the image is lowered. On the other hand, if the volume average particle diameter is less than 2.0 μm, powder characteristics as a toner, particularly poor development due to poor fluidity, and deterioration of charging characteristics are caused.
[0016]
The toner has a central shape factor of 120 or less, preferably 115 or less. When the central shape factor exceeds 120, it causes a decrease in image quality due to a decrease in transfer efficiency.
The number% of particles having a shape factor of 125 or more in the toner is 6% or more 10% or less . If the particle content exceeds 10%, it may cause a decrease in image quality due to a decrease in transfer efficiency.
The number% of particles having a shape factor of 130 or more in the toner is 0.3% or more Although it is 1% or less, Preferably it is 0.5% or less. If the particle content exceeds 1%, it may cause a decrease in image quality due to a decrease in transfer efficiency.
[0017]
The toner weight when forming a solid image with an area ratio of 100% is 1 cm per color. ² Although it is 0.1 to 0.5 mg per unit, it is preferably 0.2 to 0.45 mg.
The toner weight is 1 cm per color. ² If it exceeds 0.5 mg per hit, the fine line reproducibility on the image quality characteristic tends to deteriorate. The toner weight is 1 cm per color. ² When the amount is less than 0.1 mg, it is difficult to obtain a sufficient image density.
[0018]
The acid value in the toner is preferably 1.0 to 20 mgKOH / g, more preferably 5.0 to 18 mgKOH / g. When the acid value is less than 1.0 mgKOH / g, sufficient charging characteristics may not be obtained. On the other hand, when the acid value is larger than 20 mgKOH / g, the moisture absorption characteristics of the toner deteriorate and charging failure and environmental dependence are deteriorated. There may be a problem in charging characteristics such as a decrease in the charging.
[0019]
The absolute value of the charge amount of the toner is preferably 10 to 40 μC / g, and more preferably 15 to 35 μC / g. If the absolute value of the charge amount is less than 10 μC / g, background stains (fogging) are likely to occur, whereas if it exceeds 40 μC / g, the image density tends to decrease. The ratio of the charge amount of the toner in summer (high temperature and high humidity: 28 ° C., 85% RH) to the charge amount in winter (low temperature and low humidity: 10 ° C., 30% RH) (high temperature and high humidity charge amount) / The environmental dependency index of (low temperature and low humidity charge amount) is preferably 0.2 to 1.3, more preferably 0.7 to 1.0. If this ratio is out of the above range, charging stability and reliability under high temperature and high humidity will be impaired.
[0020]
(Toner production method)
As a method for industrially producing toner particles having both excellent particle size and particle size distribution as described above and excellent shape distribution controllability, a method of manufacturing by an emulsion polymerization aggregation method is preferable. In the present invention, at least one kind of resin fine particle dispersion and at least one colorant dispersion are mixed, and an inorganic metal salt having a bivalent or higher charge dissolved in a dispersion medium of the mixture is obtained by A method of producing toner particles by adding the mixture to the liquid mixture to form aggregates and then heating the resin to a temperature equal to or higher than the glass transition point of the resin to fuse the aggregates. By this method, the shape and shape distribution of the toner can be arbitrarily adjusted.
[0021]
More specifically, the resin fine particle dispersion can be prepared using a polymerization method such as emulsion polymerization, and the colorant dispersion is prepared by using a surfactant or the like in a solvent such as water. It can be prepared by dispersing.
In the present invention, the content of the surfactant contained in the toner particles is set to a certain level or less, and the inorganic metal salt having a charge of 2 or more used for aggregation is allowed to remain in a certain amount to leave a binder resin (resin fine particles). ) Can improve the moisture absorption characteristics of the toner by introducing ionic crosslinking therein, and as a result, a toner having a small particle size having excellent charge stability, environmental dependency, and a sharp particle size distribution can be obtained. Can do.
[0022]
The content of the surfactant remaining in the toner particles is preferably 3% by weight or less, more preferably 1% by weight or less based on the toner weight. When the content exceeds 3% by weight, charging characteristics may be deteriorated due to deterioration of moisture absorption characteristics of the toner.
[0023]
The content of the inorganic metal salt having a charge of 2 or more is preferably 1% by weight or less, more preferably 10 ppm to 1% by weight, and particularly preferably 10 ppm to 0.5% by weight based on the toner weight. When the content exceeds 1% by weight, the melt viscosity when the toner is fixed is remarkably increased, which is not preferable in terms of fixing characteristics.
[0024]
One of the reasons why it is possible to ensure the characteristic properties of the toner is that an inorganic metal salt having a charge of 2 or more is used as a flocculant when it is produced by a cohesive fusion method. This inorganic metal salt is obtained by dissolving a general inorganic metal compound or a polymer thereof in a resin fine particle dispersion. The metal element constituting the inorganic metal salt is 2A in the periodic table (long-period table). 3A, 4A, 5A, 6A, 7A, 8, 1B, 2B, 3B, and those having a charge of 2 or more belonging to the group, and those that dissolve in the form of ions in the aggregation system of resin fine particles.
[0025]
Specific examples of preferred inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, calcium polysulfide, etc. And inorganic metal salt polymers. Among these, an aluminum salt and a polymer thereof are particularly preferable. These may be used alone or in combination of two or more. In addition, an inorganic metal salt having a monovalent charge can be used in combination.
In general, in order to obtain a sharper particle size distribution, even if the valence of the inorganic metal salt is 2 valences from 1 valence, 3 valences from 2 valences, 4 valences from 3 valences, the same valence, Inorganic metal salt polymers are more suitable.
[0026]
The binder resin used for the toner is not particularly limited, and a conventionally known binder resin can be used. Specifically, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; acrylic monomers such as methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, and 2-ethylhexyl acrylate Methacrylic monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate and 2-ethylhexyl methacrylate; ethylenically unsaturated acids such as acrylic acid, methacrylic acid and sodium styrenesulfonate Monomers; Vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Homopolymers such as monomers such as olefins such as pyrene and butadiene, copolymers obtained by combining two or more of these monomers, or mixtures thereof, and epoxy resins, polyester resins, polyurethane resins, Non-vinyl condensation resins such as polyamide resins, cellulose resins, and polyether resins, or mixtures thereof with the vinyl resins, graft polymers obtained by polymerizing vinyl monomers in the presence of these resins, etc. Can be mentioned.
These may be used alone or in combination of two or more.
[0027]
The resin fine particle dispersion using the binder resin can be easily obtained by a polymerization method in a heterogeneous dispersion system such as an emulsion polymerization method, a suspension polymerization method, or a dispersion polymerization method. In addition, a polymer that has been uniformly polymerized by a solution polymerization method, a cage polymerization method, or the like is obtained by an arbitrary method such as a method in which a polymer is added together with a stabilizer into a solvent in which the polymer does not dissolve and mechanically mixed and dispersed. be able to.
[0028]
The volume average particle diameter of the resin fine particles in the resin fine particle dispersion is preferably 1 μm or less, and more preferably 10 to 500 nm. When the volume average particle diameter exceeds 1 μm, particle size distribution controllability for obtaining a sharp particle size distribution may be insufficient.
Moreover, 45-60 degreeC is preferable and the glass transition point of the said resin fine particle has more preferable 48-58 degreeC. If the glass transition point is less than 45 ° C., the obtained image is likely to cause blocking, and the storage stability may be a problem. May cause defects.
[0029]
For example, in the case of using a vinyl monomer, an ionic surfactant or the like is used. Preferably, resin fine particles are obtained by emulsion polymerization or seed polymerization using an ionic surfactant and a nonionic surfactant in combination. A dispersion can be prepared. In the case of other resins, if the resin is soluble in a solvent that is oily and has a relatively low solubility in water, the resin is dissolved in those solvents and combined with a polymer electrolyte such as an ionic surfactant or polyacrylic acid. The resin fine particle dispersion can be obtained by dispersing as fine particles in water with a disperser such as a homogenizer and then evaporating the solvent by heating or decompressing.
[0030]
The surfactant used here is an anionic surfactant such as a sulfate ester, sulfonate, phosphate, or soap; a cationic surfactant such as an amine salt type or a quaternary ammonium salt type; Nonionic surfactants such as polyethylene glycol-based, alkylphenol ethylene oxide adduct-based, polyhydric alcohol-based and the like; and various graft polymers can be mentioned, but are not particularly limited.
[0031]
When preparing a resin fine particle dispersion by the emulsion polymerization method, a small amount of unsaturated acid, for example, acrylic acid, methacrylic acid, maleic acid, styrene sulfonic acid, etc. is added as a part of the monomer component to form fine particles. A protective colloid layer can be formed on the surface, and soap-free polymerization is possible, which is particularly preferable. Even in a polymerization method other than the emulsion polymerization method, it is assumed that the particle diameter of the resin fine particles is basically sufficiently smaller than the target particle diameter at the end of aggregation (corresponding to the toner particle diameter). Further, the resin fine particle dispersion may be added and mixed at one time, or the resin fine particle dispersion may be additionally added once or a plurality of times after the aggregation step to adhere to the surface of the aggregated particles. .
[0032]
Moreover, release agent fine particles can be added as a part of the resin fine particle component. The release agent used here includes low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; fatty acid amides such as silicones, oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide; carnauba wax; Plant waxes such as rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax , Petroleum-based waxes, and modified products thereof. These may be used alone or in combination of two or more.
[0033]
These waxes are dispersed in water together with ionic surfactants, polymer electrolytes such as polymer acids and polymer bases, heated above the melting point, and can be applied with a strong shearing force and pressure discharge type dispersers. It is preferable to make a fine particle using a dispersion of particles of 1 μm or less. These release agent fine particles may be added to the mixed solvent at the same time as other resin fine particle components, or may be divided and added in multiple stages.
[0034]
Examples of the colorant used in the toner include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, balkan orange, watch ang red, permanent red, brillianthamine 3B, and brilliant. Carmine 6B, Daypon Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Various pigments, acridine, xanthene, azo, benzoquinone, azine, anthraquinone, Various dyes such as indico, dioxazine, thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, xanthene, etc. 1 type (s) or 2 or more types can be used together.
[0035]
The colorant dispersion using the colorant can be prepared by dispersing the colorant using a surfactant or the like in a solvent such as water, and any dispersion method such as a rotary shearing homogenizer can be used. In addition, a general dispersion method such as a ball mill, a sand mill, or a dyno mill having media can be used. The colorant dispersion may be added to the mixed solvent at the same time as the other fine particle dispersion, or may be divided and added in multiple stages. As the surfactant used here, the surfactant used in the preparation of the resin fine particle dispersion can be used.
[0036]
The volume average particle diameter of the colorant in the colorant dispersion is preferably 1 μm or less, and more preferably 10 to 300 nm. When the volume average particle diameter exceeds 1 μm, particle size distribution controllability for obtaining a sharp particle size distribution may be insufficient.
[0037]
In addition, when used as a magnetic toner, magnetic powder is contained. Examples of the magnetic powder used here include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and compounds containing these metals. It is done. Further, various charge control agents that are usually used, such as quaternary ammonium salts, nigrosine compounds and triphenylmethane pigments, may be added as necessary.
[0038]
Furthermore, it is possible to include a conventional external additive for toner. Specifically, inorganic fine particles such as silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate can be used by being dispersed with an ionic surfactant, a polymer acid, or a polymer base.
As a method for dispersing these magnetic powders, charge control agents, and other external additives, the same methods as those for the colorant can be used.
[0039]
After mixing these resin fine particles, colorant and the like in a solvent to prepare a uniform mixed particle dispersion, an inorganic metal salt soluble in the dispersion medium of the liquid is added and mixed to obtain desired aggregated particles. In this case, the resin fine particles, the colorant, and if necessary, the above-mentioned inorganic fine particles may be added all at once, or the fine particle components are added stepwise to form the aggregated particles. For example, a core-shell structure or a structure in which components are inclined may be used. In that case, the resin fine particle dispersion, the colorant dispersion, the release agent fine particle dispersion and the like are mixed and dispersed, and the aggregated particles are grown until the particle size reaches a certain level. If necessary, additional resin fine particles may be added to the surface of the aggregated particles by adding a resin fine particle dispersion or the like. By covering the surface of the agglomerated particles with the additional resin fine particles, it is possible to prevent the colorant, release agent, etc. from being exposed to the toner surface, which is effective in suppressing charging defects and non-uniform charging due to these exposures. is there.
[0040]
After obtaining aggregated particles having a desired particle diameter in this way, the desired toner particles can be obtained by fusing the aggregated particles by heating above the glass transition point of the resin. Here, the toner shape can be controlled from an indeterminate shape to a spherical shape by selecting the fusion heating condition. When fused for a long time at a high temperature, the toner shape becomes closer to a true sphere.
[0041]
In addition, when fusing at high temperature or fusing at a high concentration, any stabilization treatment measures such as resin fine particles used for agglomerated particles can be used to prevent intergranular fusion of the agglomerated particles and maintain a sharp particle size distribution. A method of adding a surfactant having the same charge as the above, a polymer protective colloid or the like can be employed. In this case, unlike the surfactant of the opposite charge added in the aggregation process, the stabilizing surfactant used here is adsorbed on the surface of the aggregated particles and causes the residual surfactant.
[0042]
Therefore, the most preferable embodiment in the present invention is a case where water is used as a solvent in the aggregation step, and for example, resin fine particles obtained by an emulsion polymerization method and a colorant are dispersed in water to form aggregated particles and fuse them. By adjusting the pH of the dispersion system between 2.0 and 14 to control the electric attractive force and the repulsive force of the fine particles, the progress of aggregation can be stopped and the dispersion system can be stabilized. In this case, in general, the surface potential can be stabilized at a lower pH if the surface potential is a cation type, and can be stabilized at a higher pH if the surface potential is an anionic type. From the viewpoint of chemical decomposition stability such as decomposition, and further, transient stability is problematic from the viewpoint of leading to the destruction of the aggregated particles themselves.
[0043]
The fused particles obtained by fusing can be converted into toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process. In this case, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to perform washing. Particularly when resin fine particles obtained by an emulsion polymerization method are used and the solvent is water, the washing water is used. After washing with alkaline water having a pH of 7 or more, it is preferable to wash with acidic washing water having a pH of 6 or less.
[0044]
In the drying step, an arbitrary method such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be adopted. The toner particles are preferably adjusted to have a moisture content after drying of 1.0% or less, preferably 0.5% or less.
[0045]
Further, like the conventional kneading and pulverizing toner, the toner can be used as a developer by blending various external additives. Inorganic fine particles such as silica, alumina, titania, calcium carbonate, magnesium carbonate and tricalcium phosphate as external additives, Inorganic fine particles such as silica, alumina, titania and calcium carbonate as flow aid and cleaning aid, vinyl It is also possible to add resin fine particles such as a resin, polyester, and silicone to the toner particle surface by applying a shearing force in a dry state.
[0046]
[Latent image forming process]
The latent image forming step is a step of forming an electrostatic latent image on the electrophotographic photosensitive member.
[0047]
(Electrophotographic photoreceptor)
The electrophotographic photosensitive member may be a single layer type electrophotographic photosensitive member formed of a vapor-deposited film of a charge generating material, but in the present invention, a function-separated stacked type electrophotographic photosensitive member can be preferably used. .
Examples of the laminated electrophotographic photosensitive member include those obtained by providing a photosensitive layer such as a charge generation layer and a charge transport layer on a conductive support. In the present invention, the charge generation layer includes at least the charge generation layer. It preferably contains a phthalocyanine compound.
Examples of the material for the conductive support include metal materials such as aluminum, aluminum alloys, stainless steel, copper, and nickel, polyester films on which aluminum is deposited, and paper.
The conductive support is generally subjected to a honing process or the like before the photosensitive layer is provided on the surface thereof.
[0048]
(Formation of electrostatic latent image)
The latent image forming step is not particularly limited as long as an electrostatic latent image can be formed on the electrophotographic photosensitive member. For example, a charging step for charging the electrophotographic photosensitive member, and an imagewise image An image exposure process for performing exposure and other processes as necessary may be included.
[0049]
In the charging step, for example, a contact-type charger using a conductive or semiconductive roller, brush, film, rubber blade, etc., a scorotron charger using a corona discharge, a corotron charger, etc. are known per se. A charger can be used. Among these, a contact-type charger is preferable in terms of excellent charge compensation capability.
[0050]
In the image exposure step, for example, an optical system device capable of exposing a light source such as semiconductor laser light, LED light, and liquid crystal shutter light to the surface of the electrophotographic photosensitive member in a desired image-like manner can be used.
[0051]
[First transfer process]
The first transfer step is a step of transferring a toner image formed on the electrophotographic photosensitive member to an intermediate transfer member.
In the first transfer step, for example, a contact-type transfer charger using a belt, a roller, a film, a rubber blade, etc., a scorotron transfer charger using a corona discharge, a corotron transfer charger, or the like known per se. Can be used. Among these, a contact type transfer charger is preferable in that it has excellent transfer charge compensation capability. In the present invention, in addition to the transfer charger, a peeling charger can be used in combination.
[0052]
(Intermediate transfer member)
The structure of the intermediate transfer member is generally a multilayer structure. For example, an elastic layer formed of at least rubber, elastomer, resin or the like on a conductive support, and at least one coating layer. The structure etc. which are provided are mentioned.
There is no restriction | limiting in particular as a shape of the said intermediate transfer body, Although it can select suitably according to the objective, For example, a roller shape, a belt shape, etc. are mentioned suitably. In the present invention, among these, an endless belt shape is particularly preferable from the viewpoints of color misalignment when images are superimposed, durability due to repeated use, ease of freedom of arrangement of other subsystems, and the like.
[0053]
Examples of the material of the intermediate transfer member include polyurethane resin, polyester resin, polystyrene resin, polyolefin resin, polybutadiene resin, polyamide resin, polyvinyl chloride resin, polyethylene resin, and fluorine resin. On the other hand, those obtained by dispersing and mixing conductive carbon particles, metal powder, and the like are preferably used. Among these, a polyurethane resin in which carbon particles are dispersed can be suitably used.
[0054]
[Second transfer step]
The second transfer step is a step in which the toner images on the intermediate transfer member are collectively transferred to a transfer material.
In the second transfer step, for example, a contact transfer charger, a scorotron transfer charger, a corotron transfer charger, etc. exemplified in the first transfer step can be used. Among these, a contact-type transfer charger is preferable in the same manner as the means used in the first transfer step.
[0055]
【Example】
Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following description, “part” means “part by weight”.
[0056]
Example 1
[Production of cyan toner]
-Resin fine particle dispersion 1-
Styrene ... 370 parts
n-Butyl acrylate 30 parts
Acrylic acid ... 6 parts
Dodecanethiol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 24 parts
Carbon tetrabromide ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 4 parts
550 parts of ion-exchanged water, 10 parts of nonionic surfactant (manufactured by Sanyo Kasei Co., Ltd., Nonipol 400) and 10 parts of anionic surfactant (manufactured by Daiichi Pharmaceutical Co., Ltd., Neogen R) The solution dissolved in 1 was placed in a flask to disperse and emulsify, and 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added while slowly stirring and mixing for 10 minutes. Then, after the inside of the flask was sufficiently replaced with nitrogen, the system was heated in an oil bath with stirring to 70 ° C., and emulsion polymerization was continued for 5 hours.
[0057]
The obtained latex was measured with a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). ₅₀ ) Was measured to be 155 nm, and the glass transition point of the resin was measured at a temperature rising rate of 10 ° C./min using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-50). It was 13000 when the weight average molecular weight (polystyrene conversion) was measured using THF as a solvent using the measuring device (the Tosoh company make, HLC-8020).
[0058]
-Resin fine particle dispersion 2-
Styrene ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 280 parts
n-Butyl acrylate 120 parts
Acrylic acid ... 8 parts
A solution obtained by mixing the above components, 6 parts of a nonionic surfactant (Sanyo Kasei Co., Ltd., Nonipol 400) and 12 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen R) are added to ion-exchanged water 550. The solution dissolved in the part was placed in a flask for dispersion and emulsification, and 50 parts of ion-exchanged water in which 3 parts of ammonium persulfate was dissolved was added while stirring and mixing slowly for 10 minutes. Then, after the inside of the flask was sufficiently replaced with nitrogen, the system was heated in an oil bath with stirring to 70 ° C., and emulsion polymerization was continued for 5 hours.
When various properties of the obtained latex were measured in the same manner as in the resin fine particle dispersion 1, the volume average particle diameter (D ₅₀ ) Was 105 nm, the glass transition point was 53 ° C., and the weight average molecular weight was 550,000.
[0059]
-Pigment dispersion 1-
Phthalocyanine pigment ... 50 parts
(BASF PB-FAST BLUE)
Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen R) ··· 5 parts
Ion-exchanged water ... 200 parts
The above components were dispersed with a homogenizer (manufactured by LKA, Ultra Tarrax T50) for 10 minutes, and further dispersed with an ultrasonic homogenizer, and the volume average particle diameter (D ₅₀ A blue pigment dispersion 1 having a thickness of 150 nm.
[0060]
-Partner fine particle dispersion-
Paraffin wax ... 50 parts
(Nippon Seiwa Co., Ltd., HNP0190, melting point 85 ° C.)
Cationic surfactant (manufactured by Kao Corporation, Sanizol B50) 5 parts
Ion-exchanged water ... 200 parts
The above components were sufficiently dispersed while being heated to 95 ° C. with a homogenizer (manufactured by LKA, Ultra Tarrax T50), then transferred to a pressure discharge type homogenizer for dispersion treatment, and the volume average particle size (D ₅₀ ) Gave a release agent fine particle dispersion liquid of 550 nm.
[0061]
-Production of aggregated particles-
Resin fine particle dispersion 1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 120 parts
Resin fine particle dispersion 2 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 80 parts
Pigment dispersion 1 ... 18.8 parts
Release agent fine particle dispersion ... 40 parts
10% polyaluminum chloride aqueous solution 1.5 parts
(Asada Chemical Co., Ltd., PAC100W, content of inorganic metal salt is 0.15% by weight based on toner weight)
The above components were placed in a round stainless steel flask and thoroughly mixed and dispersed with a homogenizer (manufactured by LKA, Ultra Tarrax T50), and then heated to 55 ° C. while stirring the flask in a heating oil bath. For 30 minutes to adjust the particle size and particle size distribution of the aggregated particles. At this time, the volume average particle diameter (D ₅₀ ) Was measured using a Coulter Counter (manufactured by Nikka Kikai Co., Ltd., TAII), it was 6.5 μm and the volume average particle size distribution (GSDv) was 1.20. Here, the volume average particle diameter (D ₅₀ ) And volume average particle size distribution (GSDv), the cumulative distribution is drawn from a small particle size with respect to the particle size range (channel) into which the particle size distribution to be measured is divided, and the particle size at which volume accumulation is 16% D ₁₆ , The particle size of the volume cumulative 50% is the volume D ₅₀ , The particle size of the volume cumulative 84% is the volume D ₈₄ And 50% of the volume accumulation is the volume average particle diameter D ₅₀ , D ₈₄ / D ₁₆ The value obtained from the above was defined as the volume average particle size distribution GSDv.
[0062]
-Production of fused particles-
To this aggregated particle dispersion, 3 parts of an anionic surfactant (Daiichi Pharmaceutical Co., Ltd., Neogen R) is added to stop the aggregation of the particles, stabilize the aggregated particles, seal the stainless steel flask, and seal the magnetic force. The mixture was heated to 97 ° C. with continuous stirring and held for 5 hours to fuse the aggregated particles, and the shape and shape distribution were adjusted. At this time, the volume average particle diameter (D ₅₀ ) Was measured using a Coulter Counter (manufactured by Nikka Kikai Co., Ltd., TAII), it was 6.5 μm and the volume average particle size distribution (GSDv) was 1.20.
[0063]
The fused particles were cooled, filtered, sufficiently washed with ion-exchanged water having a pH of 6.5, and dried with a freeze dryer to produce the intended cyan toner. Volume average particle diameter of toner particles (D ₅₀ ) Was measured using a Coulter Counter (manufactured by Nikka Kikai Co., Ltd., TAII), it was 6.5 μm and the volume average particle size distribution (GSDv) was 1.20. Further, when the acid value of the toner particles was determined by the KOH titration method, it was 13.0 mgKOH / g.
[0064]
Further, when the surface state of the toner particles was observed with an electron microscope, a continuous layer in which resin fine particles were fused on the particle surface was confirmed. Further, when the cross section of the toner was observed with a transmission electron microscope, the exposure of the pigment to the surface layer was hardly recognized. Further, using a Luzex image analysis apparatus (Nicore, LUZEXIII), the perimeter (ML) and the projection area (A) of 100 toners are measured, and (ML ² / A) and the average value of the shape factor SF was determined. As a result, toner particles having a center shape factor of 120, the number% of particles of SF125 or higher being 9%, and the number of particles of SF130 or higher being 0.8% were obtained. Obtained.
[0065]
[Manufacture of developer and image formation]
Further, 0.43 parts of hydrophobic silica (Cabot Co., TS720) was added to 100 parts of the cyan toner particles, and mixed by a sample mill. Then, with respect to a ferrite carrier having an average particle diameter of 50 μm coated with 1% of methacrylate (manufactured by Soken Chemical Co., Ltd.), the above externally added toner is weighed so that the toner concentration is 5%, and stirred and mixed for 5 minutes by a ball mill Thus, a developer was produced.
Using this developer, a color laser window 3310 modified copier manufactured by Fuji Xerox Co., Ltd. using an intermediate transfer belt made of polyimide resin as an intermediate transfer member in an environment of a temperature of 22 ° C. and a humidity of 55%, the solid image toner weight (TMA) is calculated. 0.45 mg / cm ² In addition, using a J-coated paper manufactured by Fuji Xerox Co., Ltd. as the final transfer material, a 1000-sheet copy test was performed, and the following image quality evaluation was performed. The results are shown in Table 1 below.
In this case, the solid image toner weight (TMA) is adjusted by adjusting the toner weight (mg / cm) per unit area of the image portion when producing a solid image with an area ratio of 100%. ² ) By measuring. The toner weight (mg / cm ² ) Was determined by a weight method by subtracting the paper weight before image formation from the paper weight after forming a solid image with an area ratio of 100%.
[0066]
<Image density>
A solid image having an area ratio of 100% was prepared, and the image density of the image portion was measured using X-Rite 404 (manufactured by X-Rite). The specific evaluation criteria are as follows, and ○ is an acceptable range.
○: Image density is 1.5 or more
Δ: Image density is 1.0 or more and less than 1.5
×: Image density is less than 1.0
[0067]
<Thin wire reproducibility>
A fine line image was formed on the photoconductor so as to have a line width of 50 μm, and this was transferred and fixed on a transfer material. The image of the fine line of the fixed image on the transfer material was observed at a magnification of 175 using a VH-6200 micro high scope (manufactured by Keyence Corporation). The specific evaluation criteria are as follows, and ◎ and ○ are acceptable.
A: The fine line is uniformly embedded in the toner, and the edge portion is not disturbed.
○: The fine lines are uniformly embedded in the toner, but there are slight jagged edges.
Δ: The fine line is uniformly embedded in the toner, but the jaggedness is noticeable at the edge.
X: The fine line is not uniformly embedded in the toner, and the jaggedness is very noticeable at the edge.
[0068]
<Tone reproducibility>
Image area ratios of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% of gradation images are prepared, and image density is measured by X-Rite 404. Was measured and the gradation was evaluated. The specific evaluation criteria are as follows, and ◎ and ○ are acceptable.
A: Gradation is very good for all gradation images from low image area to high image area
○: Good gradation in all gradation images from low image area to high image area
Δ: The gradation reproduction area in the low image area is slightly narrow, and the gradation is slightly unstable.
×: The gradation reproduction region in the high / low image area is slightly narrow and the gradation is unstable.
[0069]
<Highlight graininess>
Gradation images with image area ratios of 5% and 10% were prepared, and the obtained images were visually observed to evaluate highlight portion granularity. The specific evaluation criteria are as follows, and ◎ and ○ are acceptable.
A: Granularity is very good in both 5% and 10%.
○: Although the graininess at 5% is slightly poor, the graininess is generally good.
Δ: Slightly poor graininess at 5%
X: Both 5% and 10% have poor granularity
[0070]
(Example 2)
In Example 1, it mix | blended like Example 1 except having changed the addition amount of the pigment dispersion liquid 1 from 28.8 parts to 22.6 parts. Furthermore, in the production of aggregated particles, agglomerated particles having a volume average particle diameter of 5.9 μm and GSDv 1.19 were prepared according to Example 1 except that the aggregation temperature was maintained at 55 ° C. for 30 minutes instead of being maintained at 52 ° C. for 30 minutes. Obtained. Further, in the production of the fused particles, as in Example 1, it was held at 97 ° C. for 5 hours, the volume average particle diameter was 5.9 μm, GSDv 1.19, the central shape factor 118, and the number% of particles of SF125 or more was 9%. Cyan toner particles having a number% of SF130 or more of 0.5% were obtained. The acid value of the toner particles was determined by the KOH titration method and found to be 12.5 mgKOH / g.
Using the obtained cyan toner, a developer was produced in the same manner as in Example 1, image formation was performed, and image quality evaluation was performed in the same manner as in Example 1. The results are shown in Table 1 below.
[0071]
(Example 3)
In Example 1, it mix | blended like Example 1 except having changed the addition amount of the pigment dispersion liquid 1 from 28.8 parts to 22.6 parts. Further, in the production of the aggregated particles, the aggregated particles having a volume average particle diameter of 5.1 μm and GSDv 1.20 were prepared according to Example 1 except that the aggregation temperature was maintained at 55 ° C. for 30 minutes, but maintained at 50 ° C. for 30 minutes. Obtained. Further, in the production of the fused particles, as in Example 1, it was held at 97 ° C. for 5 hours, the volume average particle diameter was 5.1 μm, GSDv 1.20, the central shape factor 116, and the number% of SF125 or more particles was 6%. Cyan toner particles in which the number% of SF130 or higher particles was 0.3% were obtained. The acid value of the toner particles was determined by the KOH titration method and found to be 12.5 mgKOH / g.
Using the obtained cyan toner, a developer was produced in the same manner as in Example 1, image formation was performed, and image quality evaluation was performed in the same manner as in Example 1. The results are shown in Table 1 below.
[0072]
(Example 4)
In Example 1, the addition amount of the pigment dispersion 1 was changed from 18.8 parts to 26.0 parts, and the addition amount of the 10% polyaluminum chloride aqueous solution was changed from 1.5 parts to 1.6 parts. Were mixed in the same manner as in Example 1. Furthermore, in the production of the aggregated particles, the aggregated particles having a volume average particle diameter of 4.2 μm and GSDv1.21 were obtained according to Example 1 except that the aggregation temperature was maintained at 48 ° C. for 30 minutes instead of being maintained at 55 ° C. for 30 minutes. Obtained. Further, in the production of the fused particles, as in Example 1, it was held at 97 ° C. for 5 hours, and the volume average particle diameter was 4.2 μm, GSDv1.21, the central shape factor was 120, and the number% of SF125 or more was 8.5. %, The number of particles of SF130 or more was 0.8%, and cyan toner particles were obtained. The acid value of the toner particles was determined by the KOH titration method and found to be 12.1 mgKOH / g.
A developer was produced in the same manner as in Example 1 using the obtained cyan toner. Solid image toner weight (TMA) 0.30 mg / cm ² Except for the adjustment, image formation was performed in the same manner as in Example 1, and image quality evaluation was performed in the same manner. The results are shown in Table 1 below.
[0073]
(Example 5)
In Example 1, the addition amount of the pigment dispersion 1 was changed from 18.8 parts to 30.5 parts, and the addition amount of the 10% polyaluminum chloride aqueous solution was changed from 1.5 parts to 1.7 parts. Were mixed in the same manner as in Example 1. Further, in the production of the aggregated particles, the aggregated particles having a volume average particle diameter of 2.9 μm and GSDv 1.25 were prepared according to Example 1 except that the aggregation temperature was maintained at 42 ° C. for 30 minutes instead of being maintained at 55 ° C. for 30 minutes. Obtained. Further, in the production of the fused particles, as in Example 1, it was held at 97 ° C. for 5 hours, and the volume average particle diameter was 2.9 μm, GSDv 1.25, the central shape factor 120, and the number% of SF125 or more was 9.2. %, The number of particles of SF130 or more was 0.9%, and cyan toner particles were obtained. The acid value of the toner particles was determined by the KOH titration method and found to be 11.0 mgKOH / g.
A developer was produced in the same manner as in Example 1 using the obtained cyan toner. Solid image toner weight (TMA) 0.30 mg / cm ² Except for the adjustment, image formation was performed in the same manner as in Example 1, and image quality evaluation was performed in the same manner. The results are shown in Table 1 below.
[0074]
(Comparative Example 1)
In Example 1, the addition amount of the pigment dispersion 1 was changed from 18.8 parts to 11.3 parts, and instead of the 10% aqueous polyaluminum chloride solution used as the flocculant, a cationic surfactant (manufactured by Kao Corporation, The formulation was the same as in Example 1 except that SANISOL B50) was used. Further, in the production of the aggregated particles, the volume average particle diameter was 7 according to Example 1 except that the aggregation temperature was kept at 55 ° C for 30 minutes instead of being kept at 60 ° C for 30 minutes and then kept at 65 ° C for 1 hour. Aggregated particles of 0.5 μm and GSDv1.33 were obtained. Furthermore, in the production of the fused particles, a volume average particle size of 7.5 μm, GSDv 1.33, a central shape factor 145, SF125 was used according to Example 1 except that the particles were held at 93 ° C. for 5 hours instead of being held at 97 ° C. for 5 hours. Cyan toner particles in which the number% of the above particles was 95% and the number% of the particles of SF130 or more were 80% were obtained. The acid value of the toner particles was determined by the KOH titration method and found to be 13.5 mgKOH / g.
A developer was produced in the same manner as in Example 1 using the obtained cyan toner. Solid image toner weight (TMA) 0.55 mg / cm ² Except for the adjustment, image formation was performed in the same manner as in Example 1, and image quality evaluation was performed in the same manner. The results are shown in Table 1 below.
[0075]
(Comparative Example 2)
In Example 1, the amount of pigment dispersion 1 added was changed from 18.8 parts to 15.1 parts, and instead of the 10% aqueous polyaluminum chloride solution used as the flocculant, a cationic surfactant (manufactured by Kao Corporation, The formulation was the same as in Example 1 except that SANISOL B50) was used. Further, in the production of the aggregated particles, the aggregated particles having a volume average particle diameter of 6.5 μm and GSDv 1.25 were prepared according to Example 1 except that the aggregation temperature was maintained at 55 ° C. for 30 minutes instead of being maintained at 57 ° C. for 30 minutes. Obtained. Furthermore, in the production of the fused particles, a volume average particle size of 6.5 μm, GSDv 1.25, a central shape factor 132, SF125 was used in accordance with Example 1 except that it was held at 95 ° C. for 5 hours instead of being held at 97 ° C. for 5 hours. Cyan toner particles in which the number% of the above particles was 70% and the number% of the particles of SF130 or more were 60% were obtained. The acid value of the toner particles was determined by KOH titration method and found to be 13.8 mgKOH / g.
A developer was produced in the same manner as in Example 1 using the obtained cyan toner. Solid image toner weight (TMA) 0.55 mg / cm ² Except for the adjustment, image formation was performed in the same manner as in Example 1, and image quality evaluation was performed in the same manner. The results are shown in Table 1 below.
[0076]
(Comparative Example 3)
In Comparative Example 2, the solid image toner weight (TMA) was 0.6 mg / cm. ² Except for the change, the image was formed in the same manner as in Comparative Example 2, and the image quality was evaluated in the same manner. The results are shown in Table 1 below.
[0077]
[Table 1]

[0078]
From the results shown in Table 1, in the image forming method via the intermediate transfer member, in the image forming methods of Examples 1 to 5 according to the present invention, the amount of the colorant in the toner, the toner shape, and the solid image toner weight are specified numerical values. It can be seen that by defining the range, extremely excellent characteristics can be obtained in the balance of image quality characteristics. In this case, it can be seen that further excellent image quality characteristics can be obtained by further reducing the toner particle diameter.
On the other hand, as shown in the comparative example, by simply reducing the toner particle size, limiting the particle size distribution, and making it narrow distribution, fine line reproducibility, gradation reproducibility, and highlight portion granularity Although there is a tendency to improve, sufficient image quality characteristics cannot be obtained. In Comparative Example 3, if the solid image toner weight is increased in order to achieve a sufficient image density, the image density is improved, but the fine line reproducibility becomes extremely insufficient.
[0079]
(Example 6)
[Magenta toner preparation]
-Pigment dispersion 2-
Red pigment ... 50 parts
(Dainippon Seika Co., Ltd., CI Pigment Red 122)
Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen R) ··· 5 parts
Ion-exchanged water ... 200 parts
The above components were dispersed with a homogenizer (manufactured by LKA, Ultra Tarrax T50) for 10 minutes, and further dispersed with an ultrasonic homogenizer, and the volume average particle diameter (D ₅₀ ) Gave a red pigment dispersion 2 having a wavelength of 153 nm.
[0080]
In Example 1, a magenta toner was produced in the same manner as in Example 1 except that 37.6 parts of pigment dispersion 2 was added instead of 18.8 parts of pigment dispersion 1. The obtained magenta toner had a volume average particle size of 6.4 μm, GSDv 1.20, central shape factor 115, 5% number of particles of SF125 or more, and 0.5% number of particles of SF130 or more. . The acid value of the toner particles was determined by a KOH titration method and found to be 13.0 mgKOH / g. A developer was produced in the same manner as in Example 1 using the obtained magenta toner.
[0081]
[Production of yellow toner]
-Pigment dispersion 3-
Yellow pigment ... 50 parts
(C.I. Pigment Yellow 180, manufactured by Hoechst)
Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen R) ··· 5 parts
Ion-exchanged water ... 200 parts
The above components were dispersed with a homogenizer (manufactured by LKA, Ultra Tarrax T50) for 10 minutes, and further dispersed with an ultrasonic homogenizer, and the volume average particle diameter (D ₅₀ ) Was obtained as a yellow pigment dispersion 3 having a wavelength of 151 nm.
[0082]
In Example 1, a yellow toner was prepared in the same manner as in Example 1 except that 37.6 parts of pigment dispersion 3 was added instead of 18.8 parts of pigment dispersion 1. The obtained yellow toner had a volume average particle diameter of 6.4 μm, GSDv 1.19, center shape factor 116, 7% of the number of particles of SF125 or more, and 7% of the number of particles of SF130 or more. . The acid value of the toner particles was determined by KOH titration method and found to be 12.9 mgKOH / g. A developer was produced in the same manner as in Example 1 using the obtained yellow toner.
[0083]
[Image formation]
Using the magenta developer and yellow developer obtained above, and further using the cyan developer obtained in Example 1, the solid image toner weight (TMA) was adjusted as shown in Table 2 below to superimpose three colors. Except that the process black image was formed, image formation was performed in the same manner as in Example 1, and the same image quality evaluation was performed. The results are shown in Table 2 below.
[0084]
[Table 2]

[0085]
From the results in Table 2, it can be seen that the image forming method of the present invention that passes through the intermediate transfer member can provide an image with extremely excellent image quality characteristics.
[0086]
【The invention's effect】
According to the present invention, an image forming method for forming an image via an intermediate transfer member has excellent image quality characteristics (fine line reproducibility, gradation reproducibility, image reproducibility, prevention of toner scattering), and reliability. It is possible to provide a method for forming a high image.

Claims (4)

A latent image forming step of forming an electrostatic latent image on the electrophotographic photosensitive member; a developing step of developing the electrostatic latent image with toner to form a toner image; and a first step of transferring the toner image to the intermediate transfer member. In an image forming method comprising: 1 transfer step; and a second transfer step of transferring the toner image on the intermediate transfer member to a transfer material,
The toner contains a colorant and a binder resin, the content of the colorant is 2.5% by volume or more in the toner, and the volume average particle size distribution GSDv in the toner is 1.26 or less. The volume average particle diameter is 2 to 6.5 μm, the central shape factor is 120 or less, the number% of particles having a shape factor of 125 or more is 6% to 10%, and the number of particles having a shape factor of 130 or more. % Is 0.3% or more and 1% or less, and the toner weight when forming a solid image with an area ratio of 100% is 0.1 to 0.5 mg per cm ² per color. Image forming method.   The toner mixes at least one resin fine particle dispersion and at least one colorant dispersion, and mixes the inorganic metal salt having a charge of 2 or more with which the toner is dissolved in the dispersion medium. The image forming method according to claim 1, wherein the aggregate is formed by adding to the liquid, and then heating to a temperature equal to or higher than the glass transition point of the resin to fuse the aggregate.   The image forming method according to claim 2, wherein the inorganic metal salt includes at least an inorganic metal salt of Al.   The image forming method according to claim 2, wherein the inorganic metal salt includes a polymer of an inorganic metal salt.