JP5423385B2 - Positively chargeable electrostatic image developing toner and color image forming method using the toner - Google Patents

Description

  The present invention relates to a positively chargeable electrostatic image developing toner and a color image forming method using the toner. More specifically, a positive charge used to form a latent image having electrostatic characteristics such as an electrostatic latent image on a photoconductor, develop the latent image, and transfer the latent image to a recording material. The present invention relates to a toner for developing an electrostatic charge image and an electrophotographic image forming method using the toner.

  The process of adhering silica fine particles (hereinafter sometimes simply referred to as “silica”) to the toner surface in toner production is generally called external addition, and it ensures fluidity and adds storage stability at high temperatures. It is generally performed for such purposes. In recent years, since the toner has become low-temperature fixing and the toner is designed to be easily melted, the storage stability at a high temperature has become an issue.

In general, the effect of the silica fine particles used for external addition varies depending on the particle diameter.
Silica fine particles with a small primary particle size have a large surface area and cover a large amount of toner, contributing greatly to improving fluidity. Silica fine particles with a large primary particle size act as spacers between the toners, so that storage stability and silica embedding can be achieved. Greatly contributes to suppression. Therefore, these are generally used in combination.

  As described above, external addition of silica fine particles to the toner has a great effect, but also has some adverse effects. First, since the toner surface is covered, the fixability when the toner is actually printed by a printer is adversely affected. The toner after the external addition is not fixed unless the temperature is higher than the toner before the external addition. In particular, in the case of positively chargeable toner, the silica fine particles themselves exhibit negative chargeability, and thus can be mitigated by surface treatment or the like, but if the toner is coated with more silica, the charge amount of the toner may be reduced. .

  Further, it is known that when the toner is stirred for charging during image formation, a phenomenon occurs in which silica is buried in the toner and the toner charge amount is reduced. Such a decrease in the toner charge amount becomes worse as the silica coverage on the toner increases. For this reason, it is desirable to provide a toner fluidity improvement effect and a storage stability improvement effect with a smaller coverage.

  Furthermore, when silica adheres to the toner non-uniformly due to high silica cohesiveness, the initial toner charge amount becomes unstable or the toner charge amount decreases over time. Is seen. These phenomena are also unfavorable because they may cause toner malfunction in the printer.

  In Patent Document 1, spherical colloidal silica fine particles having a number average primary particle diameter of 30 to 80 nm as an external additive, a triboelectric charge amount of −50 to +300 μC / g, and a number average primary particle diameter of 5 to 25 nm. Disclosed are positively chargeable toners for electrostatic charge development containing fumed silica fine particles, each containing 0.3 to 2 parts by weight and 0.1 to 1 part by weight based on 100 parts by weight of colored resin particles. ing.

In Patent Document 2, in a positively chargeable toner for developing an electrostatic image containing positively charged colored particles containing a colorant and a binder resin and an external additive, the external additive has a work function of 4.3. In the measurement of the work function, the excitation energy (unit = eV) is plotted on the horizontal axis, and the normalized photoelectron yield expressed by the 0.5th power of the photoelectron yield per unit photon is plotted on the vertical axis. When the measured value of the normalized photoelectron yield with respect to the excitation energy is plotted on the graph, the slope of the normalized photoelectron yield with respect to the excitation energy is 5.0 to 30.0, and the resistivity is 10 ⁵ Ω · cm. There has been disclosed a positively chargeable toner for developing an electrostatic image containing a negatively chargeable external additive having the above negative charge polarity.

International Publication No. 2009/044689 JP 2008-233567 A

  The positively chargeable electrostatic image developing toners disclosed in Patent Documents 1 and 2 are not designed from the viewpoint of improving the durability of the toner. Therefore, Patent Documents 1 and 2 include positive chargeability. There is no disclosure of an external additive formulation for improving the storage stability of the toner for developing an electrostatic image.

  An object of the present invention is to improve the storage stability of toner at high temperatures. Positively chargeable electrostatic charge image developing toner that has excellent printing characteristics, has no fear of deterioration of fixability and charge reduction due to external additives, and has high fluidity and storage stability in the printer. A color image forming method was provided.

  The positively chargeable electrostatic charge image developing toner of the present invention is a positive chargeable electrostatic charge image developing toner containing a binder resin and a colorant, and an external additive. The external additive is 0.3 to 3 parts by mass of the first silica fine particles having a number average primary particle diameter of 45 to 120 nm and a triboelectric charge amount of +1000 to +5000 μC / g with respect to parts by mass. 0.1 to 2 parts by mass of second silica fine particles having a primary particle diameter of 25 to 40 nm and a triboelectric charge amount of +1000 to +7000 μC / g, and 0.005 to 0.1 parts by mass of fatty acid metal salt particles It is characterized by containing.

  The positively chargeable electrostatic image developing toner having such a structure contains the first and second silica fine particles having a number average primary particle diameter of 25 nm or more, thereby reducing the silica toner coverage and fixing ability. The adverse effect on can be suppressed. Further, in the toner for developing a positively charged electrostatic image having such a configuration, the first silica fine particles having a number average primary particle diameter of 45 nm or more are not easily embedded in the toner, so that deterioration due to silica embedding hardly occurs. , Durability can be improved. Further, the positively chargeable electrostatic image developing toner having the above-described configuration uses high-charged silica as the two types of silica fine particles, thereby suppressing the aggregation of the silica and uniform silica fine particles in the toner. As a result of the coating, high fluidity can be exhibited even with a relatively small amount of silica fine particles added. In addition, the positively chargeable electrostatic image developing toner having such a structure is improved in storage stability by being uniformly coated with silica fine particles, and the physical properties of the toner do not change even at high temperatures. . Further, the positively chargeable electrostatic image developing toner having such a configuration can be transported or used without being influenced by the environment because of the above-described storage stability. Further, the toner for developing a positively chargeable electrostatic image having such a configuration has high printing durability because the fatty acid metal salt particles are blended in an appropriate amount.

  In the positively chargeable electrostatic image developing toner of the present invention, the difference in number average primary particle diameter between the first silica fine particles and the second silica fine particles is preferably 15 nm or more.

  In the toner for developing a positively chargeable electrostatic image of the present invention, the colored resin particles contain a positively chargeable charge control agent, have a volume average particle diameter of 4 to 12 μm, and an average circularity of 0.96 or more. It is preferable that

  The color image forming method of the present invention is characterized by using the positively chargeable electrostatic image developing toner.

  The color image forming method having such a configuration can avoid the problem of ejection at the start of image formation and the ejection at the time of image formation after being left at a high temperature, and enables beautiful color image formation.

  According to the present invention, by using two types of silica fine particles having a number average primary particle diameter of 25 nm or more in combination, the silica toner coverage can be lowered, and adverse effects on fixing properties can be suppressed. Further, according to the present invention, since the first silica fine particles having a number average primary particle diameter of 45 nm or more are not easily embedded in the toner, deterioration due to silica embedding hardly occurs, and durability can be improved. Furthermore, according to the present invention, the use of highly charged silica as both types of silica fine particles suppresses aggregation of silica, and the toner is uniformly coated with silica fine particles, so that there are relatively few. Even if the amount of silica fine particles is added, high fluidity can be obtained. Further, according to the present invention, the toner is uniformly coated with silica fine particles, so that the storage stability is improved, the toner physical properties are not changed even at high temperatures, and the ejection of the toner can be prevented. Here, the ejection of toner is a phenomenon in which relatively agglomerated toner is sprayed onto a print medium such as paper in the printing process, resulting in unnecessary spots on the print medium. Due to the ejection, the print quality is greatly impaired. Furthermore, according to the present invention, by having the above storage stability, it can be transported or used without being influenced by the environment.

1 is a schematic cross-sectional view showing a typical example of an image forming apparatus used in a color image forming method of the present invention.

1. Toner for developing positively charged electrostatic image The toner for developing a positively charged electrostatic image of the present invention is a positively charged electrostatic image developing containing an external additive and colored resin particles containing a binder resin and a colorant. In the toner for use, the external additive contains 0 first silica fine particles having a number average primary particle diameter of 45 to 120 nm and a triboelectric charge amount of +1000 to +5000 μC / g with respect to 100 parts by mass of the colored resin particles. 0.1 to 2 parts by mass of second silica fine particles having a number average primary particle diameter of 25 to 40 nm and a triboelectric charge amount of +1000 to +7000 μC / g, and fatty acid metal salt particles. 0.005 to 0.1 part by mass is contained.
Hereinafter, the positively chargeable electrostatic image developing toner of the present invention may be simply referred to as “positively chargeable toner” or “toner”.

The toner of the present invention contains a predetermined amount of colored resin particles containing a binder resin and a colorant, and two types of silica fine particles having a specific number average primary particle diameter and triboelectric charge amount as external additives. .
Hereinafter, the manufacturing method of the colored resin particles, the colored resin particles obtained by the manufacturing method, and the toner of the present invention obtained through the external addition step of the colored resin particles will be described separately.

1-1. Production method of colored resin particles Generally, the production method of colored resin particles is roughly classified into dry methods such as a pulverization method and wet methods such as an emulsion polymerization aggregation method, a dispersion polymerization method, a suspension polymerization method, and a dissolution suspension method. The wet method is preferable because it is easy to obtain a toner excellent in printing characteristics such as fine line reproducibility. Among the wet methods, a polymerization method such as an emulsion polymerization aggregation method, a dispersion polymerization method, and a suspension polymerization method is preferable because a toner having a relatively small particle size distribution on the order of microns can be easily obtained. The turbid polymerization method is more preferable.

  In the emulsion polymerization aggregation method, an emulsified polymerizable monomer is polymerized to obtain resin fine particles, which are aggregated with a colorant or the like to produce colored resin particles. The dissolution suspension method produces droplets of a solution in which toner components such as a binder resin and a colorant are dissolved or dispersed in an organic solvent in an aqueous medium, and the organic solvent is removed to produce colored resin particles. Each of which is a known method.

  The colored resin particles of the present invention can be produced by employing a wet method or a dry method. When the colored resin particles are produced by employing the (A) suspension polymerization method which is preferable among the wet methods or the typical (B) pulverization method among the dry methods, the following process is performed.

(A) Suspension polymerization method (A-1) Preparation step of polymerizable monomer composition First, other monomers such as a polymerizable monomer, a colorant, a charge control agent, and a release agent as required The additive is mixed and dissolved to prepare a polymerizable monomer composition. The mixing at the time of preparing the polymerizable monomer composition is performed using, for example, a media type dispersing machine.

In the present invention, the polymerizable monomer means a monomer having a polymerizable functional group, and the polymerizable monomer is polymerized to become a binder resin. A monovinyl monomer is preferably used as the main component of the polymerizable monomer. Examples of the monovinyl monomer include styrene; styrene derivatives such as vinyl toluene and α-methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2 Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and dimethylaminoethyl methacrylate; acrylamide And amide compounds such as methacrylamide; olefins such as ethylene, propylene, and butylene; and the like. These monovinyl monomers can be used alone or in combination of two or more.
Of the monovinyl monomers, styrene, styrene derivatives, acrylic acid esters, and methacrylic acid esters are preferably used.

In order to improve the storage stability (blocking resistance) of the toner as a part of the polymerizable monomer, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer. A crosslinkable polymerizable monomer refers to a monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; ethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; N , N-divinylaniline, and divinyl compounds such as divinyl ether; compounds having three or more vinyl groups such as trimethylolpropane trimethacrylate and dimethylolpropane tetraacrylate; These crosslinkable polymerizable monomers may be used alone or in combination of two or more.
In the present invention, it is desirable to use the crosslinkable polymerizable monomer in a proportion of usually 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the monovinyl monomer. .

Further, as a part of the polymerizable monomer, it is preferable to use an arbitrary macromonomer together with the monovinyl monomer in order to improve the balance between the storage stability of the toner and the low-temperature fixability. The macromonomer is a reactive oligomer or polymer having a polymerizable carbon-carbon unsaturated bond at the end of the molecular chain and having a number average molecular weight (Mn) of usually 1,000 to 30,000. . As the macromonomer, it is preferable to use an oligomer or polymer having a Tg higher than the glass transition temperature (Tg) of a polymer (binder resin) obtained by polymerizing a polymerizable monomer.
In the present invention, the proportion of the macromonomer is usually 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the monovinyl monomer. It is desirable to use in.

  In the present invention, a colorant is used, but when a color toner (usually, four types of toners are used: black toner, cyan toner, yellow toner, and magenta toner), a black colorant, a cyan colorant, and a yellow toner are used. A colorant and a magenta colorant can be used, respectively.

  In the present invention, as the black colorant, carbon black, titanium black, and pigments such as magnetic powder such as iron oxide zinc and iron oxide nickel can be used.

  As the cyan colorant, for example, a compound such as a copper phthalocyanine pigment, a derivative thereof, and an anthraquinone pigment is used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17: 1, 60, and the like.

  As the yellow colorant, for example, azo pigments such as monoazo pigments and disazo pigments, and compounds such as condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, 186, and the like.

  Examples of the magenta colorant include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments. Specifically, C.I. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170 , 184, 185, 187, 202, 206, 207, 209, 251 and C.I. I. Pigment Violet 19 and the like.

  In the present invention, each colorant may be used singly or in combination of two or more, and is preferably used in a ratio of 1 to 10 parts by mass with respect to 100 parts by mass of the monovinyl monomer.

As another additive, a release agent is preferably used in order to improve the releasability of the toner from the fixing roll.
The release agent is not particularly limited as long as it is generally used as a release agent for toner. For example, polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; candelilla, carnauba Natural waxes such as wax, rice, wax, and jojoba; petroleum waxes such as paraffin, microcrystalline, and petrolatum; mineral waxes such as montan, ceresin, and ozokerite; synthetic waxes such as Fischer-Tropsch wax; pentaerythritol tetramyristate; Pentaerythritol esters such as pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, and pentaerythritol tetralaurate, and dipentaerythritol hexami State, dipentaerythritol hexa palmitate, and polyhydric alcohol ester compounds such as dipentaerythritol esters such as dipentaerythritol hexa laurate; and the like. These release agents may be used alone or in combination of two or more.
In this invention, it is desirable to use a mold release agent in the ratio of 0.1-30 mass parts normally with respect to 100 mass parts of monovinyl monomers, Preferably it is 1-20 mass parts.

As other additives, various charge control agents having positive chargeability can be used in order to improve the chargeability of the toner.
The charge control agent is not particularly limited as long as it is generally used as a positively chargeable charge control agent for toner. In the present invention, among the positively chargeable charge control agents, a polymerizable single agent is used. It is preferable to use a positively chargeable charge control resin because it is highly compatible with the monomer and can impart stable chargeability (charge stability) to the toner particles.
As the positively chargeable charge control resin, for example, various commercially available products can be used. As the products made by Fujikura Kasei, FCA-161P (: trade name, styrene / acrylic resin), FCA-207P (: trade name) , Styrene / acrylic resin), FCA-201-PS (: trade name, styrene / acrylic resin), and the like.
In the present invention, it is desirable to use the charge control agent in a ratio of usually 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass, with respect to 100 parts by mass of the monovinyl monomer.

It is preferable to use a molecular weight modifier as another additive.
The molecular weight modifier is not particularly limited as long as it is generally used as a molecular weight modifier for toner. For example, t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2, Mercaptans such as 4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N, N′-dimethyl-N, N′-diphenylthiuram disulfide, N, And thiuram disulfides such as N′-dioctadecyl-N and N′-diisopropylthiuram disulfide; These molecular weight modifiers may be used alone or in combination of two or more.
In this invention, it is desirable to use a molecular weight modifier in the ratio of 0.01-10 mass parts normally with respect to 100 mass parts of monovinyl monomers, Preferably it is 0.1-5 mass parts.

(A-2) Suspension step for obtaining a suspension (droplet formation step)
The polymerizable monomer composition obtained through the preparation step of the above (A-1) polymerizable monomer composition is suspended in an aqueous dispersion medium and suspended (polymerizable monomer composition dispersion). Liquid). Here, the suspension means that droplets of the polymerizable monomer composition are formed in an aqueous dispersion medium. Dispersion treatment for forming droplets is, for example, an in-line type emulsifying disperser (manufactured by Ebara Manufacturing Co., Ltd., trade name: Ebara Milder), a high-speed emulsifier / disperser (manufactured by Tokushu Kika Kogyo Co., Ltd., trade name: TK). Etc. can be carried out using a device capable of strong stirring, such as a homomixer MARK II).

In the present invention, it is preferable to use a dispersion stabilizer in the aqueous dispersion medium in order to improve the particle diameter control and the circularity of the colored resin particles in the formation of droplets.
The aqueous dispersion medium may be water alone, but can also be used in combination with a solvent that is soluble in water, such as lower alcohol and lower ketone.

  Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metals such as aluminum oxide and titanium oxide. Oxides and metal compounds such as metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; water-soluble polymer compounds such as polyvinyl alcohol, methyl cellulose, and gelatin; anionic surfactants , Organic polymer compounds such as nonionic surfactants and amphoteric surfactants;

Among the above dispersion stabilizers, a dispersion stabilizer containing a colloid of a hardly water-soluble metal hydroxide (a hardly water-soluble inorganic compound) that is soluble in an acid solution is preferably used. The dispersion stabilizers can be used alone or in combination of two or more.
The addition amount of the dispersion stabilizer is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Examples of the polymerization initiator used for polymerization of the polymerizable monomer composition include inorganic persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2 , 2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile) ), And azo compounds such as 2,2′-azobisisobutyronitrile; di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy- 2-ethylhexanoate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, di-t-butyl peroxyiso Tallates, and t- butylperoxy isobutyrate and the like organic peroxides;., Etc. Among these, organic peroxides are preferably used.

The polymerization initiator may be added at the stage before the droplet formation after the polymerizable monomer composition is dispersed in the aqueous dispersion medium containing the dispersion stabilizer. It may be added directly to the composition.
The addition amount of the polymerization initiator is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 15 parts by mass, and more preferably 1.0 to 10 parts by mass with respect to 100 parts by mass of the monovinyl monomer. More preferably, it is part by mass.

(A-3) Polymerization step (A-2) A desired suspension obtained by the step of obtaining a suspension (droplet formation step) (water system containing droplets of a polymerizable monomer composition) The dispersion medium) is heated to initiate polymerization, and an aqueous dispersion of colored resin particles is obtained.
The polymerization temperature in the present invention is preferably 50 ° C. or higher, and more preferably 60 to 98 ° C. Further, the polymerization time in the present invention is preferably 1 to 20 hours, and more preferably 2 to 15 hours.
In addition, in order to perform polymerization in a state where the droplets of the polymerizable monomer composition are stably dispersed, the step (D-2) for obtaining the suspension (A-2) in the main polymerization step is also included. Subsequently, the polymerization reaction may be allowed to proceed while performing a dispersion process by stirring.

In the present invention, a colored resin particle obtained by the polymerization step is used as a core layer, and a so-called core-shell type (or “capsule type”) colored resin obtained by forming a shell layer different from the core layer on the outer side thereof. It is preferable to use particles.
The core-shell type colored resin particles provide a balance between lowering the fixing temperature of toner and preventing aggregation during storage by coating a core layer made of a material having a low softening point with a material having a higher softening point. Can be taken.

  There is no restriction | limiting in particular as a method of manufacturing the said core-shell type colored resin particle, It can manufacture by a conventionally well-known method. An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.

A method for producing core-shell type colored resin particles by in situ polymerization will be described below.
By adding a polymerizable monomer for forming a shell layer (polymerizable monomer for shell) and a polymerization initiator for shell into an aqueous dispersion medium in which colored resin particles are dispersed, and performing polymerization. Core-shell type colored resin particles can be obtained.

  As the polymerizable monomer for the shell, the same polymerizable monomer as described above can be used. Among them, it is preferable to use monomers such as styrene and methyl methacrylate, which can produce a polymer having a Tg exceeding 80 ° C., alone or in combination of two or more.

Examples of the shell polymerization initiator used for the polymerization of the shell polymerizable monomer include potassium persulfate and persulfate metal salts such as ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxy Water-soluble azo compounds such as ethyl) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); Mention may be made of initiators.
The addition amount of the polymerization initiator for shell used in the present invention is preferably 0.1 to 30 parts by mass and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer for shell. preferable.

  The polymerization temperature of the shell layer is preferably 50 ° C. or higher, and more preferably 60 to 95 ° C. The polymerization time for the shell layer is preferably 1 to 20 hours, more preferably 2 to 15 hours.

(A-4) Washing, filtration, dehydration, and drying steps The aqueous dispersion of colored resin particles obtained after the above (A-3) polymerization step is a series of operations of washing, filtration, dehydration, and drying according to a conventional method. Is preferably repeated several times as necessary.

First, in order to remove the dispersion stabilizer remaining in the aqueous dispersion of colored resin particles, an acid or an alkali is added to the aqueous dispersion of colored resin particles and washed.
When the dispersion stabilizer used is an acid-soluble inorganic compound, an acid is added to the colored resin particle aqueous dispersion, while the dispersion stabilizer used is an alkali-soluble inorganic compound. In this case, an alkali is added to the colored resin particle aqueous dispersion.

  When an inorganic compound soluble in acid is used as the dispersion stabilizer, it is preferable to adjust the pH to 6.5 or less by adding acid to the colored resin particle aqueous dispersion. More preferably, the pH is preferably adjusted to 6 or less. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, and organic acids such as formic acid and acetic acid can be used, but the removal efficiency of the dispersion stabilizer is large and the burden on the production equipment is small. Therefore, sulfuric acid is particularly preferable.

(B) Pulverization method When the pulverization method is used to produce colored resin particles, the following process is performed.
First, a binder resin, a colorant, a charge control agent, and other additives such as a release agent added as necessary are mixed in a mixer such as a ball mill, a V-type mixer, a Henschel mixer (trade name). ), Mix using a high-speed dissolver, internal mixer, Fallberg, etc. Next, the mixture obtained as described above is kneaded while being heated using a pressure kneader, a twin-screw extrusion kneader, a roller or the like. The obtained kneaded material is coarsely pulverized using a pulverizer such as a hammer mill, a cutter mill, or a roller mill. Furthermore, after finely pulverizing using a pulverizer such as a jet mill or a high-speed rotary pulverizer, it is classified into a desired particle size by a classifier such as an air classifier or an airflow classifier, and colored resin particles obtained by a pulverization method. Get.

  In addition, other additives such as a binder resin, a colorant, and a charge control agent used in the pulverization method, and a release agent added as necessary, are those mentioned in the above (A) suspension polymerization method. Can be used. Further, the colored resin particles obtained by the pulverization method can be made into core-shell type colored resin particles by a method such as an in situ polymerization method in the same manner as the colored resin particles obtained by the suspension polymerization method (A) described above.

  As the binder resin, other resins that have been widely used for toners can be used. Specific examples of the binder resin used in the pulverization method include polystyrene, styrene-butyl acrylate copolymer, polyester resin, and epoxy resin.

1-2. Colored resin particles Colored resin particles can be obtained by a production method such as the aforementioned (A) suspension polymerization method or (B) pulverization method.
Hereinafter, the colored resin particles constituting the toner will be described. The colored resin particles described below include both core-shell type and non-core type.

The volume average particle diameter Dv of the colored resin particles constituting the toner is preferably 4 to 12 μm, more preferably 5 to 11 μm, and even more preferably 6 to 10 μm from the viewpoint of image reproducibility. .
When the volume average particle diameter Dv of the colored resin particles is less than the above range, the fluidity of the toner is lowered, the image quality is liable to be deteriorated due to fogging, and the printing performance may be adversely affected. On the other hand, when the volume average particle diameter Dv of the colored resin particles exceeds the above range, the resolution of the obtained image tends to be lowered, and the printing performance may be adversely affected.

The particle size distribution (Dv / Dn), which is the ratio of the volume average particle size (Dv) to the number average particle size (Dn), of the colored resin particles is 1.0 to 1. 3, preferably 1.0 to 1.25, and more preferably 1.0 to 1.2.
When the particle size distribution (Dv / Dn) of the colored resin particles exceeds the above range, the fluidity of the toner is lowered, the image quality is liable to be deteriorated due to fogging, and the printing performance may be adversely affected. is there.
The volume average particle diameter Dv and the number average particle diameter Dn of the colored resin particles are values measured using a particle size measuring machine.

Examples of the method for measuring the volume average particle diameter Dv and the method for calculating the particle diameter distribution Dv / Dn include the following methods. Note that the Dv measurement method and the Dv / Dn calculation method are not necessarily limited to the following methods.
First, about 0.1 g of colored resin particles are weighed, taken into a beaker, and 0.1 ml of an alkylbenzene sulfonic acid aqueous solution (manufactured by Fuji Film, trade name: dry well) is added as a dispersant. After adding 10-30 ml of Isoton II to the beaker and dispersing for 3 minutes with a 20 W (Watt) ultrasonic disperser, using a particle size measuring device (Beckman Coulter, trade name: Multisizer). , Aperture diameter: 100 μm, medium: Isoton II, number of measured particles: volume average particle diameter (Dv) and number average particle diameter (Dn) of the colored resin particles were measured under the conditions of 100,000 particles. Distribution (Dv / Dn) is calculated.

The average circularity of the colored resin particles is preferably 0.96 or more, more preferably 0.975 or more, and particularly preferably 0.978 or more from the viewpoint of image reproducibility. 0.982 or more is most preferable.
When the average circularity of the colored resin particles is less than the above range, the fine line reproducibility of printing tends to be lowered, and the printing performance may be adversely affected.

In the present invention, “circularity” is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles. The average circularity is determined by the colored resin particles. 1 is shown in the case of a perfect sphere, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated. For the average circularity, the circularity (Ci) of each particle measured for a particle group having an equivalent circle diameter of 0.6 μm or more was determined for each of n particles from the following calculation formula 1, and then averaged from the following calculation formula 2. Obtain the circularity (Ca).
Formula 1:
Circularity (Ci) = perimeter of circle equal to projected area of particle / perimeter of projected particle image

In the above calculation formula 2, fi is the frequency of particles having a circularity (Ci).
The circularity can be measured using a flow type particle image analyzer “FPIA-2000”, “FPIA-2100”, “FPIA-3000”, etc. manufactured by Sysmex Corporation.

Examples of the method for calculating the average circularity include the following methods. Note that the calculation method is not necessarily limited to the following method.
First, 10 ml of ion-exchanged water is put in a container in advance, 0.02 g of a surfactant (alkylbenzene sulfonic acid) is added as a dispersant, 0.02 g of colored resin particles are further added, and 60 W is added using an ultrasonic disperser. (Watt) A dispersion process is performed for 3 minutes. The concentration of the colored resin particles at the time of measurement is adjusted to 3,000 to 10,000 particles / μL, and 1,000 to 10,000 colored resin particles having an equivalent circle diameter of 0.4 μm or more are flow-type particle images. Measurement is performed using an analyzer (trade name: FPIA-2100, manufactured by Simex Corporation). The average circularity can be obtained from the measured value.

1-3. Colored resin particle external addition step, and positively charged electrostatic image developing toner of the present invention obtained through the external addition step Colored resin particles obtained by the above-described (A) polymerization method or (B) pulverization method Is mixed and stirred together with the first and second silica fine particles and the fatty acid metal salt particles to uniformly and suitably add the two types of silica fine particles and the fatty acid metal salt particles to the surface of the colored resin particles. (External addition).

The method of adhering and adding (external addition) the first and second silica fine particles and the fatty acid metal salt particles to the surface of the colored resin particles is not particularly limited, and can be performed using an apparatus capable of mixing and stirring. .
As an apparatus capable of mixing and stirring, for example, Henschel mixer (: trade name, manufactured by Mitsui Mining), Super mixer (: trade name, manufactured by Kawada Manufacturing), Q mixer (: trade name, manufactured by Mitsui Mining), Typical examples include a high-speed stirrer such as a mechanofusion system (trade name, manufactured by Hosokawa Micron Corporation), mechano mill (trade name, manufactured by Okada Seiko Co., Ltd.), and nobilta (: trade name, manufactured by Hosokawa Micron Corporation).

  The silica fine particles of the present invention contain first silica fine particles and second silica fine particles having different number average primary particle diameters.

The first silica fine particles are silica fine particles having a number average primary particle diameter of 45 nm to 120 nm and a triboelectric charge amount of +1000 μC / g to +5000 μC / g. If the number average primary particle diameter of the first silica fine particles is less than 45 nm, the silica fine particles may be buried in the toner, and if the number average primary particle diameter exceeds 120 nm, the external additive Sometimes, the toner fluidity is deteriorated and a printing defect may occur. Further, if the friction charge amount of the first silica fine particles is less than +1000 μC / g, the silica fine particles may be aggregated together. If the friction charge amount exceeds +5000 μC / g, Due to the influence of the surface treatment agent, the hydrophilicity of silica is increased, and there is a risk of causing printing defects such as fogging when the toner is externally added.
The triboelectric charge amount of the first silica fine particles is more preferably +2000 μC / g to +4000 μC / g, and further preferably +3000 μC / g to +4000 μC / g. The number average primary particle diameter of the first silica fine particles is more preferably 45 nm to 100 nm, and further preferably 50 nm to 80 nm. About the addition amount of 1st silica fine particle, it is 0.3-3.0 mass parts with respect to 100 mass parts of colored resin particles mentioned above, More preferably, it is 0.5-2.5 mass parts, Preferably it is 1.0-2.2 mass parts.

The second silica fine particles are silica fine particles having a number average primary particle diameter of 25 nm to 40 nm and a triboelectric charge amount of +1000 μC / g to +7000 μC / g. If the number average primary particle diameter of the second silica fine particles is less than 25 nm, the toner coverage of the silica fine particles may be unnecessarily increased, and the number average primary particle diameter is a value exceeding 40 nm. Then, at the time of external addition, the toner fluidity is deteriorated and there is a possibility that a printing defect may occur. Further, if the friction charge amount of the second silica fine particles is less than +1000 μC / g, the silica fine particles may be aggregated together. If the friction charge amount exceeds +7000 μC / g, the silica charge Due to the influence of the surface treatment agent, the hydrophilicity of silica is increased, and there is a risk of causing printing defects such as fogging when the toner is externally added.
The triboelectric charge amount of the second silica fine particles is more preferably +2000 μC / g to +6000 μC / g, and further preferably +3000 μC / g to +5000 μC / g. The number average primary particle diameter of the second silica fine particles is more preferably 25 nm to 35 nm, and further preferably 25 nm to 30 nm. About the addition amount of 2nd silica fine particle, it is 0.1-2.0 mass parts with respect to 100 mass parts of colored resin particles mentioned above, More preferably, it is 0.4-1.7 mass parts, Furthermore, Preferably it is 0.6-1.4 mass parts.

  The two types of silica fine particles used in the present invention are preferably surface-treated with a hydrophobic treatment agent having a positively chargeable functional group. In order to adjust hydrophobicity and / or positive chargeability, the two types of silica fine particles used in the present invention can be used in combination with a general hydrophobizing agent having no chargeable group. The two types of silica fine particles used in the present invention are preferably hydrophobized with a silicon compound, and more preferably hydrophobized with two or more silicon compounds. When hydrophobizing using two or more silicon compounds, in order to impart high positive chargeability, at least one of the two or more silicon compounds is a silicon compound containing an amino group, The other silicon compound is preferably a silicon compound containing no amino group.

  As the silicon compound containing an amino group, various compounds can be used without being limited to specific ones. For example, an amino group-containing silane coupling agent, an amino-modified silicone oil, a quaternary ammonium salt type silane, etc. Can be used. Among these, an amino group-containing silane coupling agent is particularly preferable from the viewpoint of positive charge imparting ability and fluidity. Specific examples of the amino group-containing silane coupling agent include, for example, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyl. Trimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, and the like can be mentioned. Among them, the effect of improving the environmental stability of charging performance is excellent, which is preferable. Is preferably a coupling agent having an aminoalkyl group, particularly preferably 3-aminopropyltriethoxysilane.

  As the silicon compound not containing an amino group, various compounds can be used without any particular limitation as long as they do not contain an amino group and express hydrophobicity. However, environmental stability and fluidity of charging performance can be used. From this point of view, for example, alkoxysilane, silane coupling agent, silazane, silicone oil, silicone resin, and the like are preferable, and alkoxysilane, silicone oil, and silicone resin are particularly preferable. Examples of the alkoxysilane include isobutyltrimethoxysilane, octyltriethoxysilane, and trifluoropropyltrimethoxysilane. Examples of the silicone oil include straight silicone oil such as dimethylpolysiloxane and methylhydrogenpolysiloxane. And modified silicone oils such as epoxy-modified silicone oil and fluorine-modified silicone oil. Examples of the silicone resin include trimethylsiloxysilicic acid.

Among silica fine particles subjected to hydrophobization treatment with a silicon compound, silica having a number average primary particle diameter of 70 nm or less is a fine powder produced by flame hydrolysis of a silicon halide compound, and is a nitrogen adsorption method (BET method). So-called fumed silica or the like having a specific surface area of 40 to 100 m ² / g measured by the above). For those having a number average primary particle diameter of more than 70 nm, colloidal silica by a sol / gel method may be used. In the first and second silica fine particles, it is preferable to use fumed silica.
The BET specific surface area of the silica before the hydrophobization treatment is S (m ² / g), and the addition amount of the silicon compound containing an amino group to the silica is A (mass%) (containing an amino group based on 100 parts by mass of silica). When the addition amount of the silicon compound containing no amino group is B (mass%) (ratio of the mass part of the silicon compound containing no amino group with respect to 100 parts by mass of silica). Regarding S, A and B, the numerical value of (A + B) / S satisfies 0.1 ≦ (A + B) /S≦0.4 and satisfies the relationship of 0.5 ≦ A / B ≦ 2.0. In particular, it is preferable that 0.1 ≦ (A + B) /S≦0.25 and 1 ≦ A / B ≦ 1.5.

  The numerical value (A + B) / S is the degree of coating of the silicon compound on the silica surface. If (A + B) / S <0.1, the silicon compound coverage is insufficient and the environmental stability of the charging performance is deteriorated. Further, if (A + B) / S> 0.4, the silicon compound is excessively coated, and the silicon compounds are easily bonded to each other, so that a self-condensation product is likely to be formed. Therefore, when the silicon compound is excessively coated, there are problems that the environmental stability of the charging performance is deteriorated, the cohesive force of silica is increased, and the fluidity is lowered.

Further, regarding the above A and B, it is necessary to satisfy the relationship of 0.5 ≦ A / B ≦ 2.0. This A / B shows the ratio of the silicon compound containing an amino group to the silicon compound containing no amino group that coats silica. If A / B <0.5, the strong negative chargeability of the silicon compound containing no amino group is dominant on the silica surface, resulting in a positive charge with a small amount of charge, or conversely negative. There is a risk of charging. Also, if A / B> 2.0, positively charged silica is obtained, but it is easily affected by humidity and the environmental stability of the charging performance is deteriorated. As a cause of being easily affected by humidity, it can be presumed that the amino group of the silicon compound containing an amino group becomes dominant on the silica surface, and the hydrophilicity increases (hydrophobicity decreases).
By setting the values of (A + B) / S and A / B high within the above range, silica having a high charge amount can be obtained.

  In the present invention, a total of two types of silica, that is, the first and second silica fine particles are used. Usually, the particle size of the silica fine particles has a unique distribution. Therefore, if the particle diameter of the first silica fine particles and the particle diameter of the second silica fine particles are not appropriately different from each other, the two types of silica fine particles may not exhibit their respective effects. Therefore, the difference in the number average primary particle size between the first silica fine particles and the second silica fine particles is preferably 15 nm or more, particularly preferably 20 nm or more, and most preferably 30 nm or more.

  Examples of the metal constituting the fatty acid metal salt particles used in the present invention include Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Zn, and the like, preferably a divalent metal. More preferably, Mg and Zn, and still more preferably Zn.

Also, fatty site of the fatty acid metal salt particles used in the present invention (R-COO ^-) The fatty acid corresponding to (R-COOH), it is preferable to use a higher fatty acid, R in the fatty acid moiety, a hydrocarbon group It may also contain organic groups other than hydrocarbon groups in addition to hydrocarbon groups. 5-30 are preferable and, as for carbon atom number of organic groups other than a hydrocarbon group or a hydrocarbon group, 10-25 are especially preferable. Specific examples of fatty acids include lauric acid (CH ₃ (CH ₂ ) ₁₀ COOH), tridecanoic acid (CH ₃ (CH ₂ ) ₁₁ COOH), myristic acid (CH ₃ (CH ₂ ) ₁₂ COOH), Pentadecanoic acid (CH ₃ (CH ₂ ) ₁₃ COOH), palmitic acid (CH ₃ (CH ₂ ) ₁₄ COOH), heptadecanoic acid (CH ₃ (CH ₂ ) ₁₅ COOH), stearic acid (CH ₃ (CH ₂ ) ₁₆ COOH) ), Arachidic acid (CH ₃ (CH ₂ ) ₁₈ COOH), behenic acid (CH ₃ (CH ₂ ) ₂₀ COOH), and lignoceric acid (CH ₃ (CH ₂ ) ₂₂ COOH).
The fatty acid moiety is not limited to one having only one carbonate moiety (—COO ⁻ ), and may have two or more carbonate moieties.

  The fatty acid metal salt particle used in the present invention is not particularly limited as long as it is a combination of the metal constituting the fatty acid metal salt particle and the fatty acid corresponding to the fatty acid moiety of the fatty acid metal salt particle, specifically, Lauric acid metal salts such as lithium laurate, sodium laurate, potassium laurate, magnesium laurate, calcium laurate, barium laurate; lithium myristate, sodium myristate, potassium myristate, magnesium myristate, calcium myristate, myristic Metal myristate such as barium acid; Lithium palmitate, Sodium palmitate, Potassium palmitate, Magnesium palmitate, Calcium palmitate, Barium palmitate, etc .; Stear Lithium phosphate, sodium stearate and potassium stearate, magnesium stearate, calcium stearate, barium stearate, stearic acid metal salts such as zinc stearate, and the like as a typical example.

The number average primary particle diameter of the fatty acid metal salt particles used in the present invention is usually 0.1 to 5 μm, preferably 0.2 to 3 μm, and more preferably 0.3 to 2 μm.
When the number average primary particle diameter of the fatty acid metal salt particles is less than the above range, the chargeability of the toner may be reduced and fogging may occur. On the other hand, when the number average primary particle diameter of the fatty acid metal salt particles exceeds the above range, white spots may occur in the printed image.

  The content of the fatty acid metal salt particles in the toner of the present invention is 0.005 to 0.1 parts by mass and preferably 0.01 to 0.08 with respect to 100 parts by mass of the colored resin particles.

As described above, the toner of the present invention contains the first and second silica fine particles having a number average primary particle diameter of 25 nm or more, so that the toner coverage of silica can be lowered and adverse effects on fixing properties can be suppressed. . In the toner of the present invention, the first silica fine particles having a number average primary particle diameter of 45 nm or more are hardly embedded in the toner, so that deterioration due to silica embedding hardly occurs and durability can be improved.
Furthermore, in the toner of the present invention, the use of highly charged silica as the first and second silica fine particles suppresses aggregation of the silica, and the toner is uniformly coated with the silica fine particles. Even with a relatively small addition amount of silica fine particles, high fluidity can be exhibited. In the toner of the present invention, the toner particles are uniformly coated with silica fine particles, so that the storage stability is improved and the physical properties of the toner are not changed even at high temperatures.
As described above, the toner of the present invention can be transported or used without being influenced by the environment by having the above-described excellent storage stability.

2. Color Image Forming Method The color image forming method of the present invention is characterized by using the above-mentioned positively chargeable electrostatic image developing toner. The color image forming method of the present invention can avoid the problem of ejection at the start of image formation and the ejection at the time of image formation after being left at high temperature, and can form a beautiful color image.

FIG. 1 is a schematic cross-sectional view showing a typical example of an image forming apparatus used in the color image forming method of the present invention. The embodiment of the color image forming method of the present invention is not necessarily limited to the method realized by the typical example of the image forming apparatus shown in FIG.
As shown in FIG. 1, in a typical example of an image forming apparatus used in the present invention, a photosensitive drum 1 as a photosensitive member is mounted so as to be rotatable in the direction of arrow A. The photosensitive drum 1 is provided with a photoconductive layer on the outer peripheral surface of a conductive support drum body. The photoconductive layer is composed of, for example, an organic photoreceptor, a selenium photoreceptor, a zinc oxide photoreceptor, an amorphous silicon photoreceptor, or the like.

  Around the photosensitive drum 1, along the circumferential direction, a charging roll 2 as a charging means, a laser beam irradiation device 3 as a latent image forming means, a developing roll 4 as a developing means, and a transfer roll 5 as a transferring means. In addition, a cleaning device 6 is disposed.

  The charging roll 2 is for uniformly charging the surface of the photosensitive drum 1 positively or negatively. By applying a voltage to the charging roll 2 and bringing the charging roll 2 into contact with the photosensitive drum 1, the photosensitive drum 1 is charged. The surface of is charged. The charging roll 2 can be replaced with charging means by corona discharge.

  The laser beam irradiation device 3 irradiates the surface of the photosensitive drum 1 with light corresponding to the image signal, irradiates the surface of the uniformly charged photosensitive drum 1 with a predetermined pattern, and the light is irradiated. In this case, an electrostatic latent image is formed on the exposed portion (in the case of reversal development), or an electrostatic latent image is formed on the portion that is not irradiated with light (in the case of regular development). Examples of other latent image forming means include those composed of an LED array and an optical system.

  The developing roller 4 is for attaching the toner 7 to the electrostatic latent image on the photosensitive drum 1. In the reverse development, the toner 7 is attached only to the light irradiation portion, and in the normal development, only the light non-irradiation portion is attached. A bias voltage is applied between the developing roll 4 and the photosensitive drum 1 so that the toner 7 is adhered.

  A supply roll 9 is provided next to the developing roll 4 in the casing 8 in which the toner 7 is accommodated. The developing roll 4 is disposed in close proximity so as to partially contact the photosensitive drum 1 and rotates in the direction B opposite to the photosensitive drum 1. The supply roll 9 contacts the developing roll 4 and rotates in the same direction C as the developing roll 4 to supply the toner 7 to the outer periphery of the developing roll 4.

Around the developing roll 4, a developing roll blade 10 as a layer thickness regulating means is disposed at a position between the contact point with the supply roll 9 and the contact point with the photosensitive drum 1. The blade 10 is made of conductive rubber or stainless steel, and a voltage of | 200 V | to | 600 V | is applied to inject charge into the toner. Therefore, the electrical resistivity of the blade 10 is preferably 10 ⁶ Ωcm or less.

  In the casing 8, toner 7 is accommodated. Since the toner 7 contains the colored resin particles and the shell portion preferably has a macromonomer having a relatively high glass transition temperature as a monomer unit, the surface of the toner 7 has low adhesiveness. The possibility that the toner 7 aggregates during storage in the casing 8 is reduced. In addition, since the toner of the present invention preferably has a relatively sharp particle size distribution, when the layer is formed by the developing roll 4, it can be substantially further increased by the layer thickness regulating means. Excellent image reproducibility.

  The transfer roll 5 is for transferring the toner image on the surface of the photosensitive drum 1 formed by the developing roll 4 to the transfer material 11. Examples of the transfer material 11 include a resin such as paper and an OHP sheet. Examples of the transfer means include a corona discharge device and a transfer belt in addition to the transfer roll 5.

  The toner image transferred to the transfer material 11 is fixed to the transfer material by fixing means. The fixing unit usually includes a heating unit and a pressure bonding unit. The toner transferred to the transfer material is heated by the heating means to melt the toner, and the melted toner is pressed and fixed to the surface of the transfer material by the pressure bonding means. In the image forming apparatus of this typical example, since the toner of the present invention is used, even if the heating temperature by the heating unit is low, the toner is easily melted, and when pressed lightly by the pressing unit, the toner becomes smooth. Since it is fixed to the surface of the transfer material, printing or copying at high speed is possible. Moreover, it is excellent in OHP permeability.

  The cleaning device 6 is for cleaning the untransferred toner remaining on the surface of the photosensitive drum 1, and is composed of, for example, a cleaning blade. Note that the cleaning device 6 is not necessarily required to be installed when a method of performing cleaning simultaneously with development by the developing roll 4 is adopted.

  Specific embodiments of the present invention will be described below in more detail with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist. Parts and% are based on mass unless otherwise specified.

1. Production of External Additive First, silica fine particles used as an external additive for toner were prepared.

(Silica fine particles 1)
100 g of silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle size of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) are dispersed in 600 g of toluene, and 7.3 g of 3-aminopropyltriethoxysilane (amino After adding and dispersing and mixing for 15 minutes and bringing into contact with silica, 5.2 g of trifluoropropyltrimethoxysilane (a silicon compound containing no amino group) is then added. Disperse and mix for minutes and contact with silica. The dispersion was distilled under reduced pressure, dried and crushed to obtain hydrophobic positively charged silica fine particles 1. (A + B) / S by this treatment was 0.25, and A / B was 1.4. The obtained silica fine particles 1 had a number average primary particle diameter of 50 nm and a triboelectric charge amount of +3300 μC / g.

(Silica fine particles 2)
In the method for producing silica fine particles 1 described above, the silica fine particles are changed from silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle diameter of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) to a BET specific surface area of 50 m ² / g. The number average primary particle size is 80 nm, the number average primary particle size is 80 nm, except that the number average primary particle size is 40 nm silica particles (trade name: Aerosil 50OX, manufactured by Nippon Aerosil Co., Ltd.). Silica fine particles 2 having a charge amount of +3000 μC / g were obtained. (A + B) / S by this treatment was 0.25, and A / B was 1.4.

(Silica fine particles 3)
In the method for producing silica fine particles 1 described above, the silica fine particles are changed from silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle diameter of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) to a BET specific surface area of 130 m ² / g. The number average primary particle diameter was changed to silica fine particles (trade name: Aerosil 130, manufactured by Nippon Aerosil Co., Ltd.), and the addition amount of 3-aminopropyltriethoxysilane was changed from 7.3 g to 19 g, and trifluoropropyltrimethoxysilane. The silica fine particles 3 having a number average primary particle size of 30 nm and a triboelectric charge amount of +3500 μC / g were obtained in the same manner as the production method of the silica fine particles 1 except that the amount of addition was changed from 5.2 g to 13.5 g. Obtained. (A + B) / S by this treatment was 0.25, and A / B was 1.41.

(Silica fine particles 4)
First, silica fine particles synthesized by suspension polymerization were prepared as silica fine particles before hydrophobization treatment.
In a 3 L glass reactor equipped with a stirrer, a dropping funnel, and a thermometer, 623.7 g of methanol, 41.4 g of water, and 49.8 g of 28% aqueous ammonia were added and mixed. The temperature of the mixed solution was adjusted to 35 ° C., and while stirring, a mixture of 1205.0 g of tetramethoxysilane and 100.6 g of tetrabutoxysilane and 418.1 g of 5.4% ammonia water were added simultaneously. Then, a mixture of tetramethoxysilane and tetrabutoxysilane was added dropwise over 6 hours and 5.4% aqueous ammonia over 5 hours. Even after the dropping was finished, the suspension was further stirred for 0.5 hours to carry out hydrolysis to obtain a suspension of hydrophilic spherical silica fine particles.
Next, an ester adapter and a condenser tube are attached to the 3 L glass reactor, and the temperature of the obtained suspension is heated to 60 to 70 ° C. to distill off methanol (distilled off). Water was added. Thereafter, the suspension is heated to a temperature of 70 to 90 ° C., and methanol is distilled off (distilled off), whereby an aqueous suspension of hydrophilic spherical silica fine particles having a solid content concentration of 20% by mass. Got.
1.4 g of 3-aminopropyltriethoxysilane was added to 500 g of this aqueous suspension of silica fine particles (100 g as a solid content), dispersed and mixed for 15 minutes, and then contacted with silica, and then 3.6 g Of trifluoropropyltrimethoxysilane was added and dispersed and mixed for 15 minutes to contact the silica. The dispersion was distilled under reduced pressure, dried and crushed to obtain hydrophobic positively charged silica fine powder 4. The obtained silica fine particles 4 had a number average primary particle diameter of 100 nm and a triboelectric charge amount of +800 μC / g.

(Silica fine particles 5)
In the method for producing silica fine particles 1 described above, the silica fine particles are changed from silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle diameter of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) to a BET specific surface area of 380 m ² / g. The number average primary particle diameter was changed to 7 nm silica fine particles (trade name: Aerosil 380, manufactured by Nippon Aerosil Co., Ltd.), and the addition amount of 3-aminopropyltriethoxysilane was changed from 7.3 g to 55.4 g. A silica fine particle having a number average primary particle size of 10 nm and a triboelectric charge amount of +5500 μC / g is carried out in the same manner as the production method of the silica fine particle 1 except that the amount of methoxysilane added is changed from 5.2 g to 39.6 g. 5 was obtained. (A + B) / S by this treatment was 0.25, and A / B was 1.4.

(Silica fine particles 6)
In the method for producing silica fine particles 1 described above, the silica fine particles are changed from silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle diameter of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) to a BET specific surface area of 200 m ² / g. The number average primary particle diameter of 12 nm is changed to silica fine particles (trade name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.), and the addition amount of 3-aminopropyltriethoxysilane is changed from 7.3 g to 29.2 g. A silica fine particle having a number average primary particle size of 20 nm and a triboelectric charge amount of +3800 μC / g was carried out in the same manner as the production method of the silica fine particle 1 except that the amount of methoxysilane added was changed from 5.2 g to 20.8 g. 6 was obtained. (A + B) / S by this treatment was 0.25, and A / B was 1.4.

(Silica fine particle 7)
In the method for producing silica fine particles 1 described above, the silica fine particles are changed from silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle diameter of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) to a BET specific surface area of 130 m ² / g. The number average primary particle diameter was changed to silica fine particles (trade name: Aerosil 130, manufactured by Nippon Aerosil Co., Ltd.), and the addition amount of 3-aminopropyltriethoxysilane was changed from 7.3 g to 18.6 g. A silica fine particle 7 having a number average primary particle diameter of 25 nm and a charge amount of +700 μC / g was carried out in the same manner as the production method of the silica fine particle 1 except that the amount of methoxysilane added was changed from 5.2 g to 46.4 g. Got. (A + B) / S by this treatment was 0.5, and A / B was 0.4.

(Silica fine particles 8)
In the method for producing silica fine particles 1 described above, the silica fine particles are changed from silica fine particles having a BET specific surface area of 50 m ² / g and a number average primary particle diameter of 30 nm (trade name: Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) to a BET specific surface area of 130 m ² / g. The number average primary particle diameter was changed to silica fine particles (trade name: Aerosil 130, manufactured by Nippon Aerosil Co., Ltd.), and the addition amount of 3-aminopropyltriethoxysilane was changed from 7.3 g to 71 g, trifluoropropyltrimethoxysilane. The silica fine particles 8 having a number average primary particle size of 35 nm and a charge amount of +3100 μC / g were obtained in the same manner as in the production method of the silica fine particles 1 except that the amount of addition was changed from 5.2 g to 59 g. (A + B) / S by this treatment was 1, and A / B was 1.2.

(Silica fine particles 9)
In the production of the silica fine particles before the hydrophobization treatment in the production method of the silica fine particles 4 described above, the mixture of tetramethoxysilane and tetrabutoxysilane takes 12 hours, 5.4% aqueous ammonia takes 10 hours, Except that each was dropped, it was carried out in the same manner as the production method of the silica fine particles 4 to obtain silica fine particles 9 having a number average primary particle diameter of 200 nm and a charge amount of +1500 μC / g.

2. Evaluation of external additive 2-1. Number average primary particle diameter The number average primary particle diameter of the external additive is obtained by taking an electron micrograph of each external additive particle and using an image processing analyzer (trade name: Luzex IID) to frame the photograph. The equivalent area diameter of the particles corresponding to the projected area of the particles was calculated under the conditions of the area ratio of the particles to the area: 2% at the maximum and the total number of treated particles: 100, and the arithmetic average value was obtained.

2-2. Triboelectric charge amount 9.95 g of carrier (trade name “NZ-3” manufactured by Powdertech Co., Ltd.) and 0.05 g of sample (silica) are weighed and put in a glass bottle with a capacity of 100 cc, and rotated at 150 rpm for 30 minutes. After rotating by a number, using a blow-off meter (trade name “TB-203” manufactured by Toshiba Chemical Co., Ltd.), blowing with a nitrogen gas pressure of 4.5 kPa and sucking with a pressure of 9.5 kPa It was measured.
The measurement was performed at a temperature of 23 ° C. and a relative humidity of 50%.

  In Table 1 below, the mixing ratio of the raw materials of the silica fine particles 1 to 9 (abbreviated as silica in the table), the values of (A + B) / S and A / B, the number average primary particle diameter, and the value of the blow-off charge amount The summary is shown.

3. Production of toner (Example 1)
Styrene and n-butyl acrylate (70 parts / 20 parts) as a polymerizable monomer, 1,2-bis (2-aminoethoxy) ethane (manufactured by Mitsui Fine Co., Ltd., trade name: EDR-148) as a primary amine compound ) 0.025 parts, C.I. I. 126 parts of Pigment Yellow was dispersed using an in-line type emulsion disperser (trade name: Ebara Milder, manufactured by Ebara Manufacturing Co., Ltd.) to obtain a polymerizable monomer mixture.
In the above polymerizable monomer mixture, 1 part of a charge control resin (manufactured by Fujikura Kasei Co., Ltd., trade name “Acrybase FCA-161P”) as a charge control agent, and fatty acid ester wax (manufactured by Nippon Oil & Fats Co., Ltd., trade name) as a release agent “WEP3”) 5 parts, polymethacrylic acid ester macromonomer (manufactured by Toa Gosei Chemical Co., Ltd., trade name “AA6”, Tg = 94 ° C.) 0.3 part as a macromonomer, divinylbenzene 0. 6 parts and 1.6 parts of t-dodecyl mercaptan as a molecular weight modifier were added, mixed and dissolved to prepare a polymerizable monomer composition.

  On the other hand, at room temperature, in an aqueous solution in which 10.2 parts of magnesium chloride (water-soluble polyvalent metal salt) is dissolved in 250 parts of ion-exchanged water, sodium hydroxide (alkali metal hydroxide) 6.2 in 50 parts of ion-exchanged water. The aqueous solution in which the part was dissolved was gradually added with stirring to prepare a magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion.

  The polymerizable monomer composition was charged into the magnesium hydroxide colloid dispersion at room temperature and stirred. 6 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) was added thereto as a polymerization initiator, and then an in-line type emulsifier / disperser (trade name, manufactured by Ebara Corporation). : Ebara Milder) was dispersed by high-speed shearing and stirring for 10 minutes at a rotational speed of 15,000 rpm to form droplets of the polymerizable monomer composition.

  A suspension (polymerizable monomer composition dispersion) in which droplets of the polymerizable monomer composition are dispersed is placed in a reactor equipped with a stirring blade, heated to 90 ° C., and polymerized. The reaction was started. When the polymerization conversion reached almost 100%, 2,2′-azobis (shell polymerization initiator dissolved in 1 part of methyl methacrylate and 10 parts of ion-exchanged water as shell polymerizable monomer) 0.3 part of 2-methyl-N- (2-hydroxyethyl) -propionamide) (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086, water-soluble) was added, and the reaction was continued at 90 ° C. for 4 hours. Thereafter, the reaction was stopped by cooling with water to obtain an aqueous dispersion of colored resin particles having a core-shell structure.

The aqueous dispersion of the colored resin particles was dropped at room temperature while stirring sulfuric acid, and acid washing was performed until the pH became 6.5 or lower. Subsequently, filtration separation was performed, 500 parts of ion-exchanged water was added to the obtained solid content to make a slurry again, and water washing treatment (washing, filtration, dehydration) was repeated several times. Subsequently, filtration separation was performed, and the obtained solid content was put in a container of a dryer and dried at 45 ° C. for 48 hours to obtain dried colored resin particles.
The obtained colored resin particles had a volume average particle size (Dv) of 9.7 μm, a particle size distribution (Dv / Dn) of 1.14, and an average circularity of 0.987.

  With respect to 100 parts of the obtained colored resin particles, 1.5 parts of the silica fine particles 1 as the first silica fine particles, 1.1 parts of the silica fine particles 3 as the second silica fine particles, and zinc stearate 0.06 part (trade name: SPZ-100F, manufactured by Sakai Chemical Industry Co., Ltd.) is added and mixed at a peripheral speed of 30 m / s for 6 minutes using a high-speed stirrer (trade name: Henschel mixer, manufactured by Mitsui Mining Co., Ltd.). The toner of Example 1 was produced by stirring and externally adding.

(Example 2)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using colored resin particles, in Example 1 above, 1.5 parts of silica fine particles 2 were added to 100 parts of colored resin particles instead of 1.5 parts of silica fine particles 1. The mixing and stirring after the addition was performed in the same manner as in Example 1 to produce the toner of Example 2.
The silica fine particles 2 correspond to the first silica fine particles contained in the toner of the present invention, and the silica fine particles 3 correspond to the second silica fine particles contained in the toner of the present invention.

(Example 3)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using the colored resin particles, in Example 1 described above, 1.5 parts of silica fine particles 1, 1.1 parts of silica fine particles 3 and 0.1 part of zinc stearate with respect to 100 parts of colored resin particles. Instead of adding 06 parts, 1.5 parts of silica fine particles 2, 1.1 parts of silica fine particles 8, and 0.06 parts of magnesium stearate (manufactured by Sakai Chemical Industry Co., Ltd., SPX-100F) are added. did. The mixing and stirring after the addition was performed in the same manner as in Example 1, and the toner of Example 3 was produced.
The silica fine particles 2 correspond to the first silica fine particles contained in the toner of the present invention, and the silica fine particles 8 correspond to the second silica fine particles contained in the toner of the present invention.

(Comparative Example 1)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using colored resin particles, 1.1 parts of silica fine particles 5 were added to 100 parts of colored resin particles instead of adding 1.1 parts of silica fine particles 3 in Example 1 above. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to produce a toner of Comparative Example 1.
The silica fine particles 1 used in Comparative Example 1 correspond to the first silica fine particles contained in the toner of the present invention. However, the silica fine particles 5 used in Comparative Example 1 do not correspond to the second silica fine particles because they do not satisfy the condition of the number average primary particle diameter of the second silica fine particles contained in the toner of the present invention. .

(Comparative Example 2)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using colored resin particles, instead of adding 1.5 parts of silica fine particles 1 and 1.1 parts of silica fine particles 3 to 100 parts of colored resin particles in Example 1 above, 1.5 parts of silica fine particles 2 and 1.1 parts of silica fine particles 6 were added. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to produce a toner of Comparative Example 2.
Note that the silica fine particles 2 used in Comparative Example 2 correspond to the first silica fine particles contained in the toner of the present invention. However, since the silica fine particles 6 used in this Comparative Example 2 do not satisfy the condition of the number average primary particle diameter of the second silica fine particles contained in the toner of the present invention, they do not correspond to the second silica fine particles. .

(Comparative Example 3)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the manufacturing process of the toner using the colored resin particles, 1.1 parts of silica fine particles 6 were added to 100 parts of the colored resin particles instead of adding 1.5 parts of the silica fine particles 1 in Example 1 above. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to prepare a toner of Comparative Example 3.
The silica fine particles 6 used in Comparative Example 3 do not satisfy the condition of the number average primary particle diameter of the first silica fine particles contained in the toner of the present invention, and thus do not correspond to the first silica fine particles. . Further, the silica fine particles 3 used in Comparative Example 3 correspond to the second silica fine particles.

(Comparative Example 4)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using the colored resin particles, 1.1 parts of silica fine particles 7 were added to 100 parts of the colored resin particles in Example 1 instead of 1.1 parts of the silica fine particles 3. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to prepare a toner of Comparative Example 4.
The silica fine particles 1 used in Comparative Example 4 correspond to the first silica fine particles contained in the toner of the present invention. However, since the silica fine particles 7 used in Comparative Example 4 do not satisfy the condition of the triboelectric charge amount of the second silica fine particles contained in the toner of the present invention, they do not correspond to the second silica fine particles.

(Comparative Example 5)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using the colored resin particles, in Example 1 above, instead of adding 1.5 parts of silica fine particles 1 to 100 parts of colored resin particles, 2 parts of silica fine particles 4 were added. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to prepare a toner of Comparative Example 5.
The silica fine particles 3 used in Comparative Example 5 correspond to the second silica fine particles contained in the toner of the present invention. However, the silica fine particles 4 used in Comparative Example 5 do not meet the first silica fine particles because they do not satisfy the condition of the triboelectric charge amount of the first silica fine particles contained in the toner of the present invention.

(Comparative Example 6)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using colored resin particles, zinc stearate was added in Example 1 above, but no fatty acid metal salt was added in this comparative example. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to prepare a toner of Comparative Example 6.
The silica fine particles 1 correspond to the first silica fine particles contained in the toner of the present invention, and the silica fine particles 3 correspond to the second silica fine particles contained in the toner of the present invention.

(Comparative Example 7)
The process up to the production of the colored resin particles is the same as in Example 1 above.
During the production process of the toner using colored resin particles, in Example 1 above, instead of adding 1.5 parts of silica fine particles 1 to 100 parts of colored resin particles, 2 parts of silica fine particles 9 were added. Other additives and addition amount, and mixing and stirring after the addition were performed in the same manner as in Example 1 to prepare a toner of Comparative Example 7.
The silica fine particles 3 used in Comparative Example 7 correspond to the second silica fine particles contained in the toner of the present invention. However, since the silica fine particles 9 used in Comparative Example 7 do not satisfy the condition of the number average primary particle diameter of the first silica fine particles contained in the toner of the present invention, they do not correspond to the first silica fine particles. .

3. Evaluation of Toner For the toners of Examples 1 to 3 and Comparative Examples 1 to 7, fluidity evaluation, charge amount measurement, and printing test were performed.

3-1. Evaluation of fluidity Three types of sieves each having an opening of 150 μm, 75 μm, and 45 μm were stacked in this order from above, and 4 g of the toner sample was precisely weighed and placed on the uppermost sieve. Next, these three types of sieves were vibrated for 15 seconds under the condition of vibration intensity scale 4 using a powder measuring machine (trade name “Powder Tester” manufactured by Hosokawa Micron Co., Ltd.), and remained on each sieve. The developer weight was measured. Substituting each measured value into the following formula 3 to obtain the values of a, b, and c, and then substituting the values of a, b, and c into formula 4 to calculate the fluidity value Calculated as a percentage. Measurement was performed three times per sample, and the average value was defined as the fluidity value of the toner sample.
Formula 3:
a = [(polymer weight (g) remaining on 150 μm sieve) / 4 g] × 100
b = [(polymer weight (g) remaining on 75 μm sieve) / 4 g] × 100 × 0.6
c = [(weight of polymer remaining on 45 μm sieve (g)) / 4 g] × 100 × 0.2
Formula 4:
Fluidity (%) = 100− (a + b + c)

3-2. Measurement of charge amount 9.5 g of a carrier (trade name “NZ-3”, manufactured by Powder Tech Co., Ltd.) and 0.5 g of a sample (toner) are weighed and put in a glass bottle with a capacity of 100 cc, and 30 minutes, 150 rpm. After rotating at the rotation speed, using a blow-off meter (trade name “TB-203” manufactured by Toshiba Chemical Co., Ltd.), blow at a pressure of 4.5 kPa of nitrogen gas, and suction at a pressure of 9.5 kPa, and the amount of blow-off charge Was measured.
The measurement was performed at a temperature of 23 ° C. and a relative humidity of 50%.

3-3. Printing test 3-3-1. Printing durability (N / N environment, H / H environment)
For the printing durability test, a commercially available non-magnetic one-component developing type printer (HL-3040CN) was used, and the toner cartridge to be developed was filled with the toner to be tested, and then the printing paper was set.
The printer is allowed to stand for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), and then continuously prints up to 15,000 sheets at 5% print density in the same environment. Was done.
Black solid printing (printing density 100%) was performed every 500 sheets, and the printing density of the black solid image was measured using a reflection type image densitometer (manufactured by Macbeth, trade name: RD918). After that, white solid printing (printing density 0%) is performed, the printer is stopped in the middle of white solid printing, and the toner in the non-image area on the developed photoreceptor is covered with an adhesive tape (manufactured by Sumitomo 3M Limited, product Name: Scotch mending tape 810-3-18), and then peeled off and affixed to printing paper. Next, the whiteness (B) of the printing paper on which the adhesive tape is affixed is measured with a whiteness meter (trade name: ND-1 manufactured by Nippon Denshoku Co., Ltd.). The whiteness (A) was measured and the difference in whiteness (B−A) was defined as the fog value (%). Smaller values indicate better fog and better.
The above test was repeated up to 10,000 sheets, and the number of continuous prints capable of maintaining an image quality with a print density of 1.3% or more and a fog value of 3% or less was examined.
The same printing durability test was also performed in a high temperature and high humidity (H / H) environment (temperature: 35 ° C., humidity: 80%).
In Table 1, “10000 <” indicates that the image quality with the print density of 1.3% or more and the fog value of 3% or less was maintained even at the time of 10,000 sheets.

3-3-2. Initial ejection For the printing durability test, a commercially available non-magnetic one-component developing type printer (HL-3040CN) was used. After the toner cartridge of the developing device was filled with the toner to be tested, continuous printing was performed. Continuous printing was performed in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%).
Printing is performed at a halftone print density of 30%. Count the number of spots of 0.3 x 0.3 mm or more on the halftone due to the toner ejected from the toner cartridge onto the printing paper, and print until this number reaches zero. I did it.
The evaluation is performed by the number of printed sheets until the number of spots appearing on the printed material becomes zero, and the smaller the number of printed sheets indicates that the image can be printed without any problem in image quality.

3-3-3. Ejected after being left at high temperature A commercially available non-magnetic one-component developing type printer (HL-30 40CN) was used for the printing durability test. After the toner cartridge of the developing device was filled with the toner to be tested, the toner cartridge was left in a dryer at 50 ° C. for 120 hours, and the removed cartridge and printing paper were set in a printer, and continuous printing was performed. Continuous printing was performed in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%).
Printing is performed at a halftone print density of 30%. Count the number of spots of 0.3 x 0.3 mm or more on the halftone due to the toner ejected from the toner cartridge onto the printing paper, and print until this number reaches zero. I did it.
The evaluation is performed by the number of printed sheets until the number of spots appearing on the printed material becomes zero, and the smaller the number of printed sheets indicates that the image can be printed without any problem in image quality.

  Table 2 below summarizes the physical properties and blending ratios of the toner materials of Examples 1 to 3 and Comparative Examples 1 to 7 and the evaluation of the toner. In the columns of “first silica fine particles” and “second silica fine particles”, ○ is used when the silica used corresponds to the first or second silica fine particles, and × is indicated otherwise. Respectively. Further, in the column “the difference in number average primary particle diameter is 15 nm or more”, the difference between the number average primary particle diameters of the two types of silica used is 15 nm or more, and the difference is less than 15 nm. X was described respectively.

(Summary of results)
First, the toners of Comparative Example 1, Comparative Example 2 and Comparative Example 4 are examined. One of the two types of silica used in the toners of Comparative Example 1 and Comparative Example 2 corresponds to the first silica fine particles, but the other has a number average primary particle size that is too small, so the second silica fine particles Not applicable. One of the two types of silica used in the toner of Comparative Example 4 corresponds to the first silica fine particles, but the other does not correspond to the second silica fine particles because the triboelectric charge amount is small. Therefore, the toners of Comparative Example 1, Comparative Example 2 and Comparative Example 4 have 0 to 2 initial ejection evaluations and 20 to 40 ejection evaluations after being left at a high temperature. The toner was likely to be ejected.
Next, the toners of Comparative Example 3, Comparative Example 5 and Comparative Example 7 will be examined. One of the two types of silica used in the toner of Comparative Example 3 corresponds to the second silica fine particle, but the other does not correspond to the first silica fine particle because the number average primary particle diameter is too small. One of the two types of silica used in the toner of Comparative Example 5 corresponds to the second silica fine particle, but the other does not correspond to the first silica fine particle because the triboelectric charge amount is too small. One of the two types of silica used in the toner of Comparative Example 7 corresponds to the second silica fine particle, but the other does not correspond to the first silica fine particle because the number average primary particle diameter is too large. Therefore, the toners of Comparative Example 3, Comparative Example 5 and Comparative Example 7 have an initial ejection evaluation of 0 to 10 sheets and an evaluation of ejection after high temperature exposure of 30 to 50 sheets. The toner was likely to be ejected.
Subsequently, the toner of Comparative Example 6 will be examined. The two types of silica used in the toner of Comparative Example 6 correspond to either the first or second silica fine particles, but do not contain fatty acid metal salt particles, so the number of durable printing sheets is 7,000. Therefore, the toner has low printing durability.

Consider the toners of Examples 1 to 3. The two types of silica used in the toners of Examples 1 to 3 were toners corresponding to either the first or second silica fine particles. Therefore, the toners of Examples 1 to 3 were not confirmed to be ejected both in the initial stage and after being left at a high temperature, and in a normal temperature / normal humidity (N / N) environment, a high temperature / high humidity (H / H) environment. In any of the cases below, the toner was excellent in printing durability and good.
In addition, as fatty acid metal salt particles, zinc stearate particles were added in Example 1 or 2, and magnesium stearate particles were added in Example 3, respectively. Regardless of the type of fatty acid metal salt particles, both cases are good. Printing durability.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roll 3 Laser beam irradiation apparatus 4 Developing roll 5 Transfer roll 6 Cleaning apparatus 7 Toner 8 Casing 9 Supply roll 10 Developing roll blade 11 Transfer material

Claims (4)

In the positively chargeable electrostatic charge image developing toner containing a colored resin particle containing a binder resin and a colorant, and an external additive,
The external additive is based on 100 parts by mass of the colored resin particles.
0.3 to 3 parts by mass of first silica fine particles having a number average primary particle diameter of 45 to 120 nm and a triboelectric charge amount of +1000 to +5000 μC / g,
0.1 to 2 parts by mass of second silica fine particles having a number average primary particle size of 25 to 40 nm and a triboelectric charge amount of +1000 to +7000 μC / g, and
A toner for developing a positively chargeable electrostatic charge image, comprising 0.005 to 0.1 parts by mass of fatty acid metal salt particles.   2. The positively chargeable electrostatic image developing toner according to claim 1, wherein a difference in number average primary particle diameter between the first silica fine particles and the second silica fine particles is 15 nm or more.   The colored resin particles contain a positively chargeable charge control agent, have a volume average particle diameter of 4 to 12 μm, and an average circularity of 0.96 or more. The positively chargeable electrostatic image developing toner described.   A color image forming method using the positively chargeable electrostatic image developing toner according to any one of claims 1 to 3.

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