JP2010128312A - Positively charging toner for electrostatic charge image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positively charging toner for electrostatic charge image development, the toner exhibiting good rising property of charging even in a low temperature and low humidity environment, little initial fog, and excellent initial printing performance, for imparting stable chargeability and fluidity with lapse of time to toner particles, keeping thin line reproducibility even after continuous printing in a great number of sheets, hardly causing degradation of image quality such as fog but having excellent durable printing performance even in a high temperature and high humidity environment. <P>SOLUTION: The positively charging toner for electrostatic charge image development contains color resin particles comprising a binder resin, a colorant and a charge control agent, and an external additive, wherein the toner contains, as the external additive, an external additive A and an external additive B. The external additive includes fatty acid alkali metal salt particles or fatty acid alkaline earth metal salt particles having a number average primary particle diameter of 0.1 to 1 μm, with the content of the fatty acid alkali metal salt particles or the fatty acid alkaline metal salt particles being 0.01 to 0.5 part by weight with respect to 100 parts by weight of the color resin particles. The external additive B includes spherical silica fine particles having a number average primary particle diameter of 40 to 200 nm and a sphericity of 1 to 1.3. The content of the spheric silica fine particles is 0.2 to 2 parts by weight with respect to 100 parts by weight of the color resin particles. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a positively chargeable toner for developing an electrostatic charge image (hereinafter simply referred to as “positively chargeable toner”) used for developing an electrostatic latent image in electrophotography, electrostatic recording method, electrostatic printing method and the like. In particular, the present invention relates to a positively chargeable toner for developing an electrostatic image excellent in initial printing performance and durable printing performance.

  In an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and an electrostatic printing apparatus, a desired image is formed by developing an electrostatic latent image formed on a photoreceptor with toner for developing an electrostatic image. An image forming method to be formed is widely implemented and applied to a copying machine, a printer, a facsimile, a multi-function machine and the like.

  For example, in an electrophotographic apparatus using electrophotography, generally, the surface of a photoconductor made of a photoconductive material is uniformly charged by various means, and then an electrostatic latent image is formed on the photoconductor. . Next, the electrostatic latent image is developed using toner, the toner image is transferred onto a recording material such as paper, and then fixed by heating or the like to obtain a copy.

  The toner used in the image forming apparatus includes a negatively chargeable toner and a positively chargeable toner. Positively chargeable toners are preferably used in recent years because they suppress the generation of ozone and provide good chargeability.

  In addition, the toner used in the image forming apparatus is generally an inorganic fine particle or an organic fine particle having a particle diameter smaller than that of a colored resin particle (toner particle) for the purpose of improving functions such as charging stability and fluidity of the toner. An external additive such as is attached and added (externally added) to the surface of the toner particles.

  In a toner obtained using a conventional external additive, it may be difficult to obtain the toner charge rising property in the initial stage of printing, and in particular, the toner charge rising property may be low temperature low humidity or high temperature high humidity. It is easily affected by the usage environment in harsh environments. As a result, image quality deterioration due to initial fog or the like is likely to be caused, and there is a problem that the initial printing performance is adversely affected.

  In addition, in the continuous printing process of a large number of sheets, external additives are buried in the surface of the toner particles due to mechanical stress in the developing device (increase in the number of contact between toner particles due to stirring or the like) and / or the like. Alternatively, a problem of liberation (detachment) from the surface of the toner particles is likely to occur, and it becomes difficult to impart stable charging properties (charging stability) to the toner particles over time. As a result, the fine line reproducibility of printing is deteriorated, and image quality deterioration such as fogging is caused, which adversely affects the durable printing performance.

  For this reason, in the initial stage of printing, the charge rising property is excellent even in a use environment under severe conditions, and in the continuous printing process of a large number of sheets, the number of contact between toner particles by stirring or the like increases in the developing device. However, problems such as burying and / or liberation of the external additive do not occur, the state in which the external additive is suitably attached is maintained over time, and the toner particles have stable chargeability (charging stability). Development of a toner that can be applied to the toner is desired.

  In Patent Document 1, for the purpose of suppressing the liberation of external additives, negatively chargeable silica fine particles (manufactured by Nippon Aerosil Co., Ltd., trade name: RX200, average particle diameter: 15 nm) with respect to 100 parts by mass of toner base particles. 1 part by mass, 0.5 part by mass of titanium oxide fine particles, 0.5 part by mass of positively chargeable silica fine particles (manufactured by Nippon Aerosil Co., Ltd., trade name: NA50H, average particle size: 30 nm), and magnesium stearate powder 0.1 A toner obtained by externally adding parts by mass in this order is disclosed.

  In Patent Documents 2 and 3, the average primary particle diameter is 12 nm with respect to 100 parts by weight of toner base particles for the purpose of providing a toner for a cleaner-less image forming apparatus that does not substantially require a means for cleaning a photoreceptor. After 0.8 parts by weight of hydrophobic silica and 0.7 parts by weight of hydrophobic silica having an average primary particle size of 40 nm were added and mixed, 0.4 parts by weight of monodispersed spherical silica, 0.5 nm of hydrophobic titanium oxide 0.5 A toner obtained by externally adding 0.2 parts by weight of another part by weight, 0.2 parts by weight of other hydrophobic titanium oxide, and 0.2 parts by weight of metal soap (manufactured by NOF Corporation, fine calcium stearate) is disclosed.

  In Patent Document 4, for the purpose of improving the cleaning property, with respect to 100 parts of toner particles, 0.3 parts of zinc stearate particles having an average particle diameter Ds50 of 2.9 μm and an average particle diameter of about hydrophobically treated particles are about. A toner obtained by externally adding 0.6 parts of 10 nm silica fine particles is disclosed.

  In Patent Document 5, for the purpose of reducing the amount of free external additive, 15 g of silica fine particles having an average particle diameter of 12 nm (RX200 manufactured by Nippon Aerosil Co., Ltd.) and 6 g of specific alumina are externally added to 3 kg of toner base particles. Furthermore, 15 g of silica fine particles (RX50 manufactured by Nippon Aerosil Co., Ltd.) having an average particle size of 40 nm and 15 g of titanium oxide fine particles were externally added, and magnesium stearate particles having an average particle size of 1.9 μm (manufactured by Nippon Oil & Fats Co., Ltd.). MM-2) A toner obtained by externally adding 3 g is disclosed.

  However, as a result of the study by the present inventors, the toners disclosed in Patent Documents 1 to 5 have good charge rising property and excellent initial printing performance even in a severe environment, and perform continuous printing of a large number of sheets. However, it is difficult to say that the toner maintains the fine line reproducibility, hardly deteriorates in image quality due to fog and the like, and has excellent durability printing performance.

JP 2004-219935 A JP-A-2005-274643 JP 2005-274722 A Japanese Patent Laid-Open No. 9-236942 JP 2006-151563 A

  The object of the present invention is that, even in a low-temperature and low-humidity environment, charging startability is good, initial fog is small, initial printing performance is excellent, and charging and fluidity stable over time can be imparted to toner particles. Positive chargeability for electrostatic image development that maintains fine line reproducibility even when continuous printing is performed, and is resistant to image degradation due to fog, etc., even in high-temperature and high-humidity environments, and has excellent durability printing performance To provide toner.

  As a result of intensive studies to achieve the above object, the present inventors have identified an external additive A (fatty acid alkali metal salt particles or fatty acid alkaline earth metal salt particles) having specific characteristics as an external additive. By using a specific amount of external additive B (spherical silica fine particles) having specific characteristics, it is possible to obtain good charge start-up property, low initial fog and excellent initial printing performance even in a low temperature and low humidity environment. At the same time, stable charging and fluidity can be imparted to the toner particles over time, fine line reproducibility is maintained even when continuous printing of a large number of sheets is performed, and image quality due to fog or the like is maintained even in a high temperature and high humidity environment. As a result, the present invention was completed based on these findings.

In other words, the positively chargeable toner for developing an electrostatic charge image of the present invention is a positively chargeable toner for developing an electrostatic charge image containing a colored resin particle containing a binder resin, a colorant, and a charge control agent, and an external additive. In
As the external additive, including external additive A and external additive B,
The external additive A is a fatty acid alkali metal salt particle or fatty acid alkaline earth metal salt particle having a number average primary particle size of 0.1 to 1 μm, and the fatty acid alkali metal salt particle or fatty acid alkaline earth metal. The content of the salt particles is 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the colored resin particles,
The external additive B is spherical silica fine particles having a number average primary particle size of 40 to 200 nm and a sphericity of 1 to 1.3, and the content of the spherical silica fine particles is 100 parts by weight of colored resin particles. Is a positively chargeable toner for developing an electrostatic charge image, characterized by being 0.2 to 2 parts by weight based on the weight of the toner.

In the positively chargeable toner for developing an electrostatic image, the toner further includes an external additive C as an external additive,
The external additive C is silica fine particles having a number average primary particle size of 5 to 25 nm, and the content of the silica fine particles is 0.2 to 2 parts by weight with respect to 100 parts by weight of the colored resin particles. Is preferred.

  In the positively chargeable toner for developing an electrostatic charge image, the average circularity of the colored resin particles is preferably 0.96 to 0.995.

  According to the positively chargeable toner for developing an electrostatic image of the present invention as described above, even in a low-temperature and low-humidity environment, the charge rising property is good, initial fog is small, initial printing performance is excellent, and stable over time. Chargeability and fluidity can be imparted to toner particles, fine line reproducibility is maintained even when continuous printing is performed on many sheets, and image quality deterioration due to fog and the like hardly occurs even in a high temperature and high humidity environment. Provided is a positively chargeable toner for developing an electrostatic image that is excellent in printing performance.

The positively chargeable toner for developing an electrostatic charge image of the present invention is a positively chargeable toner for developing an electrostatic charge image containing a binder resin, a colorant, a colored resin particle containing a charge control agent, and an external additive. ,
As the external additive, including external additive A and external additive B,
The external additive A is a fatty acid alkali metal salt particle or fatty acid alkaline earth metal salt particle having a number average primary particle size of 0.1 to 1 μm, and the fatty acid alkali metal salt particle or fatty acid alkaline earth metal. The content of the salt particles is 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the colored resin particles,
The external additive B is spherical silica fine particles having a number average primary particle size of 40 to 200 nm and a sphericity of 1 to 1.3, and the content of the spherical silica fine particles is 100 parts by weight of colored resin particles. 0.2 to 2 parts by weight based on the weight.

  Hereinafter, the positively chargeable toner for developing an electrostatic image of the present invention (hereinafter sometimes simply referred to as “toner”) will be described.

  The toner of the present invention is composed of colored resin particles containing a binder resin, a colorant, and a charge control agent, and two types of external additives having specific characteristics.

  The binder resin is not particularly limited as long as it is generally used as a binder resin for toner, and examples thereof include polystyrene, styrene-butyl acrylate copolymer, polyester resin, and epoxy resin. It is done. These binder resins may be used alone or in combination of two or more.

  In general, the method for producing 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 a toner having excellent printing characteristics can be easily obtained. 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 (1) Preparation step of polymerizable monomer composition First, a polymerizable monomer, a colorant, a charge control agent, and, if necessary, other additives such as a release agent. Are mixed, dissolved or dispersed to prepare a polymerizable monomer composition. In preparing the polymerizable monomer composition, for example, a media type wet pulverizer is used.

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 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 particularly preferably used.

As a part of the polymerizable monomer, any crosslinkable polymerizable monomer can be used together with the monovinyl monomer in order to improve the storage stability (blocking resistance) of the toner. A crosslinkable polymerizable monomer refers to a monomer having two or more polymerizable functional groups.
The crosslinkable polymerizable monomer is not particularly limited as long as it is generally used as a crosslinkable polymerizable monomer for toner, and examples thereof include divinylbenzene, divinylnaphthalene, and these. Aromatic divinyl compounds such as derivatives; bifunctional ethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; heteroatom-containing divinyl compounds such as N, N-divinylaniline and divinyl ether; trimethylol And compounds having three or more vinyl groups such as propanetrimethacrylate and dimethylolpropanetetraacrylate. These crosslinkable polymerizable monomers may be used alone or in combination of two or more.
In the present invention, the crosslinkable polymerizable monomer is usually used at a ratio of 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, with respect to 100 parts by weight of the monovinyl monomer. desirable.

Further, as a part of the polymerizable monomer, an arbitrary macromonomer can be used together with the monovinyl monomer in order to improve the balance between the storage stability and low-temperature fixability of the toner.
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 weight, preferably 0.03 to 5 parts by weight, and more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the monovinyl monomer. It is desirable to use in.

  As the colorant, when producing a color toner (usually, four types of toners of black toner, cyan toner, yellow toner, and magenta toner are used), a black colorant, a cyan colorant, a yellow colorant, and Magenta colorants can each be used.

  As the black colorant, carbon black, titanium black, and pigments such as magnetic powders 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 weight with respect to 100 parts by weight of the polymerizable monomer.

As other additives, a positively or negatively chargeable charge control agent can be used to improve the chargeability of the toner.
The charge control agent is not particularly limited as long as it is generally used as a charge control agent for toner. Among charge control agents, the charge control agent has compatibility with a binder resin (or polymerizable monomer). High and stable chargeability (charge stability) can be imparted to the toner particles, and therefore, a positively or negatively chargeable charge control resin is preferred. Further, from the viewpoint of obtaining a positively chargeable toner, positive charge The charge control resin is more preferably used.
As the positively chargeable charge control resin, commercially available products manufactured by Fujikura Kasei Co., Ltd. can be used. For example, FCA-161P (: trade name, styrene / acrylic resin), FCA-207P (: trade name, styrene / Acrylic resin) and FCA-201-PS (trade name, styrene / acrylic resin).
As the negatively chargeable charge control resin, a commercial product manufactured by Fujikura Kasei Co., Ltd. can be used. For example, FCA-626N (: trade name, styrene / acrylic resin), FCA-748N (: trade name, styrene / Acrylic resin) and FCA-1001N (trade name, styrene / acrylic resin).
In the present invention, it is desirable to use the charge control agent in a proportion of usually 0.3 to 10 parts by weight, preferably 0.5 to 8 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

As another additive, a release agent can be used 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 paraffin wax, 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 Kisa myristate, dipentaerythritol hexa palmitate, and dipentaerythritol esters such as dipentaerythritol hexa laurate, polyhydric alcohol ester compounds such polyglycerol fatty acid ester; 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 weight part normally with respect to 100 weight part of polymerizable monomers, Preferably it is 1-20 weight part.

As other additives, a molecular weight modifier can be used to adjust the molecular weight and molecular weight distribution.
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, and N , N′-dioctadecyl-N, N′-diisopropyl thiuram disulfide and other thiuram disulfides; These molecular weight modifiers may be used alone or in combination of two or more.
In the present invention, the molecular weight regulator is preferably used in a proportion of 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the polymerizable monomer.

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

As the aqueous dispersion medium, water alone may be used, but a solvent that is soluble in water, such as lower alcohol and lower ketone, may be used in combination.
In droplet formation, it is preferable to use a dispersion stabilizer in the aqueous dispersion medium in order to control the particle size of the colored resin particles and improve the circularity.

  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, the dispersion stabilizer containing a metal compound, particularly a colloid of a hardly water-soluble metal hydroxide, can narrow the particle size distribution of the colored resin particles, and can stabilize the dispersion after washing. Since the residual amount of the agent is small, the obtained polymerized toner is preferable because it can reproduce an image clearly and does not deteriorate the image quality under high temperature and high humidity.

  The said dispersion stabilizer can be used 1 type or in combination of 2 or more types. The amount of the dispersion stabilizer added is preferably 0.1 to 20 parts by weight and more preferably 0.2 to 10 parts by weight with respect to 100 parts by weight 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 used for the polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer, and 0.3 to The amount is more preferably 15 parts by weight, and further preferably 1.0 to 10 parts by weight.

(3) Polymerization step A desired suspension (aqueous dispersion medium containing droplets of a polymerizable monomer composition) obtained by the step (2) of obtaining a suspension (droplet formation step) is used. Then, the polymerization is started by heating to obtain an aqueous dispersion of colored resin particles.
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 the polymerization in a state where the droplets of the polymerizable monomer composition are stably dispersed, in the main polymerization step, following the step (2) obtaining the suspension (droplet formation step), The polymerization reaction may be allowed to proceed while performing a dispersion treatment by stirring.

As colored resin particles having a core-shell structure (or also referred to as “capsule type”) obtained by forming colored resin particles obtained by the polymerization step as a core layer and forming a shell layer different from the core layer on the outer side thereof. Good.
The colored resin particles having a core-shell structure are formed by coating a core layer made of a material having a low softening point with a shell layer, which is a material having a higher softening point, thereby reducing the fixing temperature of the toner and agglomeration during storage. It is possible to balance prevention.

  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 weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight 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.

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

First, in order to remove the dispersion stabilizer remaining in the aqueous dispersion of colored resin particles, it is preferable to perform washing by adding an acid or an alkali to the aqueous dispersion of colored resin particles.
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). , Mitsui Mining Co., Ltd .: registered trademark), high-speed dissolver, internal mixer, Fallberg and the like.

  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.

(Colored resin particles)
Hereinafter, the particle size characteristics of the colored resin particles obtained by the above-described (A) suspension polymerization method or (B) pulverization method 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 is preferably 5 to 15 μm, more preferably 6 to 12 μm, and further preferably 7 to 10 μm from the viewpoint of forming a high-quality image. preferable.

  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. is there. On the other hand, when the volume average particle diameter (Dv) of the colored resin particles exceeds the above range, it becomes difficult to form a high-definition image, the resolution of the obtained image is likely to be lowered, and the printing performance is adversely affected. There is a case.

  The particle size distribution (Dv / Dn), which is the ratio between the volume average particle size (Dv) and the number average particle size (Dn) of the colored resin particles, is 1.0 to 1. 3 is preferable, and 1.0 to 1.2 is more preferable.

  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.

  In addition, 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 device, for example, a particle size measuring device manufactured by Beckman Coulter, Inc. It can be measured using (trade name: Multisizer).

The average circularity of the colored resin particles is preferably from 0.96 to 0.995, more preferably from 0.97 to 0.995, from the viewpoint of forming a high quality image. More preferably, it is 0.995.
When the average circularity of the colored resin particles is less than the above range, the fine line reproducibility of toner printing tends to be lowered, and the printing performance may be adversely affected.

Here, “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 particles having an equivalent circle diameter of 0.4 μm or more was determined for each of n particles from the following calculation formula 1, and then the average circularity was calculated from the following calculation formula 2. The degree (Ca) is obtained.
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 and the average circularity can be measured using, for example, a flow type particle image analyzer “FPIA-2000”, “FPIA-2100”, “FPIA-3000” manufactured by Sysmex Corporation.

(5) External Addition Step In this step, the external additive A (fatty acid alkali metal salt particles specified in the present invention is added to the colored resin particles obtained by the above-described (A) suspension polymerization method or (B) pulverization method. Or fatty acid alkaline earth metal salt particles) and external additive B (spherical silica fine particles) are added and mixed and stirred, so that the external additive A and external additive B are suitably applied to the surface of the colored resin particles. Add adhesion (external addition).

  The method of adding and adding (externally adding) the external additive to the surface of the colored resin particles is not particularly limited. For example, as a high-speed stirrer, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd .: registered trademark), Super Mixer (: trade name, manufactured by Kawada Seisakusho Co., Ltd.), Q mixer (: trade name, manufactured by Mitsui Mining Co., Ltd.), Mechano Fusion System (: trade name, manufactured by Hosokawa Micron Corporation: registered trademark), Mechano Mill (: trade name, Okada Seiko Co., Ltd.) And Nobilta (: trade name, manufactured by Hosokawa Micron Co., Ltd .: registered trademark).

The external additive A specified in the present invention is fatty acid alkali metal salt particles and fatty acid alkaline earth metal salt particles.
In the present invention, the “fatty acid alkali metal salt particles” and the “fatty acid alkaline earth metal salt particles” used as the external additive A refer to particles of a salt of a fatty acid and an alkali metal or an alkaline earth metal. .

“Fatty acid” is a generic term for a carboxylic acid having one carboxyl group (—COOH) (R—COOH) having a chain structure.
In this invention, it is preferable that the fatty acid which comprises a fatty-acid alkali metal salt and a fatty-acid alkaline-earth metal salt is a fatty acid (higher fatty acid) with many carbon numbers of an alkyl group (R-).

Examples of the higher fatty acid 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), lignoceric acid (CH ₃ (CH ₂ ) ₂₂ COOH) and the like.

  In the present invention, the fatty acid alkali metal salt particles and the fatty acid alkaline earth metal salt particles used as the external additive A include fatty acids and alkali metals (Li, Na, K, Rb, Cs) or alkaline earth metals (Be, It is a particle of a salt with Mg, Ca, Sr, Ba).

Specific examples of the fatty acid alkali metal salt and the fatty acid alkaline earth metal salt include alkali lauric acid salts such as lithium laurate, sodium laurate, and potassium laurate; magnesium laurate, calcium laurate, and barium laurate. Alkaline earth metal laurates such as; alkali metal myristate such as lithium myristate, sodium myristate and potassium myristate; alkaline earth metal myristate such as magnesium myristate, calcium myristate and barium myristate Salts; alkali metal palmitates such as lithium palmitate, sodium palmitate, and potassium palmitate; magnesium palmitate, calcium palmitate, and barium palmitate An alkaline earth metal salt of palmitate; an alkali metal stearate such as lithium stearate, sodium stearate, and potassium stearate; an alkaline earth metal stearate such as magnesium stearate, calcium stearate, and barium stearate; Etc. These fatty acid alkali metal salts and fatty acid alkaline earth metal salts may be used alone or in combination of two or more.
Among these, in the present invention, a specific amount of fatty acid alkali metal salt particles or fatty acid alkaline earth metal salt particles having a number average primary particle size of 0.1 to 1 μm is used.

  The fatty acid alkali metal salts and fatty acid alkaline earth metal salts listed above are fatty acid alkali metal salt particles and fatty acid alkaline earth metal salts having the number average primary particle size (0.1 to 1 μm) specified in the present invention. Although it will not specifically limit if it is particle | grains, It is preferable that carbon number of the alkyl group of a fatty acid which comprises a fatty-acid alkali metal salt and a fatty-acid alkaline-earth metal salt is 12-24, and it is 14-22. More preferably, it is 16-20. The alkali metal is preferably lithium, and the alkaline earth metal is preferably magnesium and calcium.

  Specific examples of fatty acid alkali metal salts and fatty acid alkaline earth metal salts that are preferably used in the present invention include lithium stearate, magnesium stearate, and calcium stearate.

  In the present invention, various commercially available products can be used as the fatty acid alkali metal salt particles and the fatty acid alkaline earth metal salt particles specified as the external additive A. For example, commercially available products from Sakai Chemical Industry Co., Ltd. SPL-100F (lithium stearate, number average primary particle size: 0.71 μm), SPX-100F (magnesium stearate, number average primary particle size: 0.72 μm), and SPC-100F (calcium stearate, number average primary particle) (Diameter: 0.51 μm).

  In the present invention, the number average primary particle diameter of the fatty acid alkali metal salt particles or fatty acid alkaline earth metal salt particles used as the external additive A is 0.1 to 1 μm, preferably 0.2 to 0.8 μm. More preferably, it is 0.3 to 0.8 μm.

  When the number average primary particle size of the external additive A is less than the above range, problems such as aggregation of the external additives A and embedding of the external additive A in the colored resin particles are likely to occur. May adversely affect printing performance. On the other hand, when the number average primary particle size of the external additive A exceeds the above range, the external additive A is easily released (desorbed) from the colored resin particles, and functions as a desired external additive ( Functions such as charging stability and fluidity) cannot be sufficiently imparted to the toner particles, which may adversely affect the toner printing performance.

  In the present invention, the content of the fatty acid alkali metal salt particles or the fatty acid alkaline earth metal salt particles used as the external additive A is 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the colored resin particles, Preferably it is 0.01-0.3, More preferably, it is 0.02-0.2 weight part.

  When the content of the external additive A is less than the above range, functions as a desired external additive (functions such as charging stability and fluidity) cannot be obtained, and the printing performance of the toner is adversely affected. May affect. On the other hand, if the content of the external additive A exceeds the above range, the charge rising property is liable to occur, and furthermore, stable chargeability and fluidity over time cannot be imparted to the toner particles. The toner printing performance may be adversely affected.

  In addition, as the external additive A specified in the present invention, one that has been subjected to a hydrophobization treatment using a hydrophobization treatment agent described later can also be used.

  In the present invention, the “spherical silica fine particles” used as the external additive B refers to silica fine particles having a number average primary particle size of 40 to 200 nm and a sphericity of 1 to 1.3.

  In the present invention, the number average primary particle size of the spherical silica fine particles used as the external additive B is 40 to 200 nm, preferably 50 to 150 nm.

  When the number average primary particle size of the external additive B is less than the above range, problems such as aggregation of the external additives B and embedding of the external additive B in the colored resin particles easily occur. May adversely affect printing performance. On the other hand, when the number average primary particle size of the external additive B exceeds the above range, the external additive B is easily released (desorbed) from the colored resin particles, and functions as a desired external additive ( Functions such as charging stability and fluidity) cannot be sufficiently imparted to the toner particles, which may adversely affect the toner printing performance.

  In the present invention, the spherical silica fine particles used as the external additive B have a sphericity of 1 to 1.3, preferably 1 to 1.25.

  When the sphericity of the external additive B exceeds the above range, the charge rising property is likely to be poor, the charge amount distribution is likely to be widened, initial fog is generated, and the initial printing performance is inferior. Stable chargeability and fluidity over time cannot be sufficiently imparted to toner particles, and it is difficult to maintain fine line reproducibility in continuous printing of a large number of sheets, and image quality deterioration due to fog etc. hardly occurs, and durability Printing performance may be inferior. These tendencies are remarkable in severe environments such as low temperature and low humidity and high temperature and high humidity.

Here, “sphericity” is defined as a value obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of the particle by the actual projected area (Sr) of the particle.
In addition, the sphericity (Sc / Sr) of the colored resin particles is calculated by analyzing the Sc and Sr with an image processing analysis device using a photograph of the colored resin particles taken with an electron microscope. It is a value obtained by arithmetic averaging.

In the present invention, the method for producing spherical silica fine particles used as the external additive B is not particularly limited as long as silica fine particles having a high sphericity can be obtained. For example, the sol-gel method, deflagration method, colloidal method, Further, a method such as a melting method can be employed.
Among these methods, since the spherical silica fine particles used as the external additive B in the present invention are easily obtained, the melting method and the colloidal method are preferable, and the melting method is more preferable.

  In the present invention, various commercially available products can be used as the spherical silica fine particles identified as the external additive B. For example, UFP-30H (number average primary particle size: 110 nm) is available as a commercially available product manufactured by Denki Kagaku Kogyo. , Sphericity: 1.13); commercially available products manufactured by Shin-Etsu Chemical Co., Ltd., X-24-9163A (number average primary particle size: 140 nm, sphericity: 1.12), and KMPX100 (number average primary particle size) : 100 nm, sphericity: 1.12);

  In the present invention, the spherical silica fine particles used as the external additive B should be those hydrophobized with a hydrophobizing agent from the viewpoint of enhancing the effect of suitably attaching and adding (external addition) to the surface of the colored resin particles. Is preferred. As the hydrophobizing agent, for example, a silane coupling agent, silicone oil, or the like can be used.

Examples of the silane coupling agent include disilazane such as hexamethyldisilazane; cyclic silazane; trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane. , Methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, Alkyl silane compounds such as vinyltriacetoxysilane; γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, N-phenyl Aminosilane compounds such as -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, and N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane And the like.
Examples of the silicone oil include dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, and amino-modified silicone oil.
These hydrophobizing agents may be used alone or in combination of two or more. The amount of the hydrophobizing agent used is preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight, and still more preferably 10 to 30 parts by weight with respect to 100 parts by weight of the spherical silica fine particles.

In the present invention, the method of hydrophobizing the spherical silica fine particles used as the external additive B with the hydrophobizing agent is not particularly limited as long as it is generally a method of hydrophobizing the silica fine particles. Methods such as a dry method and a wet method can be employed.
Specifically, as a dry method, the external additive B is stirred at a high speed while the hydrophobic treatment agent is dropped or sprayed. As a wet method, the hydrophobic treatment agent is dissolved in an organic solvent, Examples thereof include a method of adding the external additive B while stirring the solvent.

  In the present invention, the content of the spherical silica fine particles used as the external additive B is 0.2 to 2 parts by weight, preferably 0.2 to 1 part by weight with respect to 100 parts by weight of the colored resin particles.

  When the content of the external additive B is less than the above range, functions as a desired external additive (functions such as charging stability and fluidity) cannot be obtained, and toner printing performance is adversely affected. May affect. On the other hand, when the content of the external additive B exceeds the above range, the charge rising property is liable to occur, and further, the external additive B is easily released (desorbed) from the colored resin particles. In other words, the toner particles cannot be imparted with stable chargeability and fluidity, and the toner printing performance may be adversely affected.

  In the present invention, in addition to using the above-mentioned external additive A (fatty acid alkali metal salt particles or fatty acid alkaline earth metal salt particles) and external additive B (spherical silica fine particles) as external additives, In order to enhance the effect, it is preferable to use the external additive C (silica fine particles) in combination.

  In the present invention, the number average primary particle size of the silica fine particles used as the external additive C is preferably 5 to 25 nm.

  When the number average primary particle size of the external additive C is less than the above range, problems such as aggregation of the external additives C and embedding of the external additive C in the colored resin particles easily occur. May adversely affect printing performance. On the other hand, when the number average primary particle size of the external additive C exceeds the above range, the external additive C is easily released (desorbed) from the colored resin particles, and functions as a desired external additive ( Functions such as charging stability and fluidity) cannot be sufficiently imparted to the toner particles, which may adversely affect the toner printing performance.

  In the present invention, various commercially available products can be used as the silica fine particles used as the external additive C. Examples of commercially available products manufactured by Cabot Corporation include TG-820F (number average primary particle size: 7 nm), and TG-7120F (number average primary particle size: 22 nm); As a commercially available product manufactured by Clariant Japan, HDK2150 (number average primary particle size: 12 nm);

  In the present invention, the silica fine particles used as the external additive C should be those hydrophobized with a hydrophobizing agent from the viewpoint of improving the effect of suitably attaching and adding (external addition) to the surface of the colored resin particles. preferable. As the hydrophobizing agent, the same hydrophobizing agent as the spherical silica fine particles used as the external additive B described above can be used.

  In the present invention, the content of the silica fine particles used as the external additive C is preferably 0.2 to 2 parts by weight, and 0.3 to 1.5 parts by weight with respect to 100 parts by weight of the colored resin particles. More preferably, it is 0.3 to 1.2 parts by weight.

  When the content of the external additive C is less than the above range, functions as a desired external additive (functions such as charging stability and fluidity) cannot be obtained, and the printing performance of the toner is adversely affected. May affect. On the other hand, if the content of the external additive C exceeds the above range, charge rising property tends to be poor, and furthermore, stable chargeability and fluidity over time cannot be imparted to the toner particles. The toner printing performance may be adversely affected.

  In this step, the order in which each of the external additives described above is added to the colored resin particles, followed by mixing and stirring for external addition treatment is not particularly limited. For example, all the external additives are added to the colored resin particles at once. The external addition treatment can be carried out by mixing and stirring, but first, only the external additive A having a relatively large particle size is added to the colored resin particles, followed by mixing and stirring, and then external addition having a relatively small particle size. Agent B can be added and mixed and stirred, and external additive C having a relatively small particle size can be added and mixed and stirred for external addition.

(toner)
The toner obtained through the steps (1) to (5) uses a specific amount of an external additive A (fatty acid alkali metal salt particles or fatty acid alkaline earth metal salt particles) having specific characteristics as an external additive. In addition, by using a specific amount of the external additive B (spherical silica fine particles) having specific characteristics, the charging property is excellent even in a low-temperature and low-humidity environment, and there is little initial fogging, and stable charging characteristics over time. Flowability can be imparted to toner particles, fine line reproducibility is maintained even when a large number of sheets are continuously printed, and image quality deterioration due to fog and the like hardly occurs even in a high temperature and high humidity environment. Excellent toner.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited only to these examples. Parts and% are based on weight unless otherwise specified.
The test methods performed in the examples and comparative examples are as follows.

(1) Particle size characteristics of external additive (1-1) Number average primary particle size The number average primary particle size of the external additive is obtained by taking an electron micrograph of each particle, and using the image processing analyzer (Nireco). Under the conditions of the particle area ratio to the frame area: 2% at the maximum and the total number of processed particles: 100, the equivalent circle diameter corresponding to the projected area of the particles was calculated by the company, product name: Luzex IID) The arithmetic average value was obtained.

(1-2) Sphericality An external additive was photographed with a transmission electron micrograph, and the photograph was taken with an image processing analysis device (manufactured by Nireco Corporation, trade name: Luzex IID). Under the condition of 2% and the total number of treated particles: 100, the area (Sc) of the circle having the diameter of the absolute maximum length of the particle and the actual projected area (Sr) of the particle are analyzed, and the sphericity (Sc / Sr) ) Was calculated, and the arithmetic average value was obtained.

(2) Particle size characteristics of colored resin particles (2-1) Volume average particle size (Dv), number average particle size (Dn), and particle size distribution (Dv / Dn)
About 0.1 g of the colored resin particles were weighed and taken in a beaker, and 0.1 ml of an alkylbenzenesulfonic acid aqueous solution (manufactured by Fuji Film, trade name: Drywell) was added as a dispersant. To the beaker, 10-30 ml of a special electrolyte (Beckman Coulter, trade name: Isoton II-PC) was further added and dispersed for 3 minutes with a 20 W ultrasonic dispersion machine, followed by a particle size measuring machine (Beckman Coulter (Trade name: Multisizer), aperture diameter: 100 μm, medium: Isoton II-PC, number of measured particles: volume average particle diameter (Dv) of colored resin particles under conditions of 100,000 The number average particle size (Dn) was measured, and the particle size distribution (Dv / Dn) was calculated.

(2-2) Average circularity Into a container, 10 ml of ion-exchanged water is put in advance, 0.02 g of a surfactant (alkylbenzenesulfonic acid) as a dispersant is added, and 0.02 g of colored resin particles is further added. Then, the dispersion treatment was performed with an ultrasonic disperser at 60 W for 3 minutes. The concentration of the colored resin particles at the time of measurement is adjusted to be 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 was performed using an analyzer (trade name: FPIA-2100, manufactured by Simex Corporation). The average circularity was determined from the measured value.
The circularity is shown in the following calculation formula 1, and the average circularity is the number average.
Formula 1:
(Circularity) = (Perimeter of circle equal to projected area of particle) / (Perimeter of particle projection image)

(3) Toner printing characteristics (3-1) Initial printing test (under L / L environment)
For the initial printing test, a commercially available non-magnetic one-component developing type printer (printing speed: A4 size 20 sheets / minute) was used, and the toner cartridge was filled in the toner cartridge of the developing device, and then the printing paper was set.
After being left for 24 hours in a low-temperature, low-humidity (L / L) environment (temperature: 10 ° C., humidity: 20%), after performing 20 continuous prints at 5% print density in the same environment, initial fogging Values were measured as follows.
After continuous printing of 20 sheets, solid white printing (0% printing density) is performed, printing is stopped halfway, and the toner in the non-image area on the photoconductor after development is adhesive tape (manufactured by Sumitomo 3M Limited). Product name: Scotch mending tape 810-3-18) and then peeled off and the adhesive tape affixed to a new printing paper is used as a measurement sample, and the color tone (B) of this measurement sample is measured as whiteness It measured using the meter (Nippon Denshoku make, model name: NDW-1D).
On the other hand, an unused adhesive tape directly attached to a new printing paper was used as a reference sample, and the color tone (A) of this reference sample was measured in the same manner as the measurement sample.
Each color tone is expressed as coordinates in the L * a * b * space, the color difference ΔE (| A−B |) is calculated from the color tone (A) of the measurement sample and the color tone (B) of the reference sample, and the initial fog value ΔE is calculated. did. It can be evaluated that the smaller the initial fog value, the less the fog and the better the image quality.

(3-2) Fine line reproducibility test (under N / N environment)
For the fine line reproducibility test, the same printer as described above was used, and after the toner cartridge of the developing device was filled with toner, the printing paper was set.
After standing for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), 2 × 2 dot lines (width: about 85 μm) continuously in the same environment Images were formed and continuous printing was performed up to 10,000 sheets.
For every 500 sheets, density distribution data of line images was collected using a printing evaluation system (trade name: RT2000, manufactured by YA-MA).
Based on the density distribution data of the collected line image, the line width is determined based on the line width formed on the first sheet of print paper, with the full width of the line image at the half value of the maximum density as the line width. The number of continuously printed sheets that can maintain the difference of 10 μm or less was examined.

(3-3) Durability printing test (N / N environment, H / H environment)
In the durability printing test, the same printer as described above was used, and the toner cartridge was filled in the toner cartridge of the developing device, and then the printing paper was set.
After standing for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), continuous printing is performed up to 10,000 sheets at a 1% print density in the same environment. I did it.
Black solid printing (printing density 100%) was performed every 500 sheets, and the printing density of the black solid image was measured using a reflective image densitometer (trade name: RD918, manufactured by Macbeth). 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 photosensitive member is adhesive tape (manufactured by Sumitomo 3M Ltd., 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 (manufactured by Nippon Denshoku Co., Ltd., model name: NDW-1D). The whiteness (A) was measured and the whiteness difference (B−A) was defined as the fog value ΔE. Smaller values indicate better fogging.
The number of continuously printed sheets that can maintain the image quality with the print density of 1.3 or more and the fog value ΔE of 3 or less was examined.
The same durable printing test was also conducted in a high temperature and high humidity (H / H) environment (temperature: 32 ° C., humidity: 80%).

(Method for producing hydrophobic spherical silica fine particles used as external additive B)
(Production Example 1)
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% ammonia water were added and mixed, and the temperature of the mixed solution was 35 ° C. It adjusted so that it might become.
While stirring the temperature-adjusted mixed solution, dropwise addition of a mixture of 1205.0 g of tetramethoxysilane and 100.6 g of tetrabutoxysilane and 418.1 g of 5.4% aqueous ammonia was started at the same time. The mixture with butoxysilane was added dropwise over 6 hours, and 5.4% aqueous ammonia was added dropwise over 5 hours.
Even after the completion of each dropping, the mixed solution 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 resulting suspension of the hydrophilic spherical silica fine particles is heated to a temperature of 60 to 70 ° C. to distill off methanol (distillation). After removing water), water is added and heated until the temperature of the suspension reaches 70 to 90 ° C., methanol is completely distilled off (distilled off), and an aqueous suspension of hydrophilic spherical silica fine particles is obtained. Obtained.

While stirring the obtained aqueous suspension of hydrophilic spherical silica fine particles, 11.6 g of methyltrimethoxysilane was started to be dropped at room temperature, and was dropped over 0.5 hours. Even after the completion of the dropwise addition, the aqueous suspension was further stirred for 12 hours for hydrophobization.
1440 g of methyl isobutyl ketone is added to the hydrophobized aqueous suspension, and then heated until the temperature of the aqueous suspension reaches 80 to 110 ° C., and the azeotrope is distilled off over 10 hours ( Then, the aqueous suspension was cooled to room temperature.
To the cooled aqueous suspension, 1000 g of methanol was added and stirred for 10 minutes, and then treated with 3000 G for 10 minutes in a centrifuge to separate the supernatant. The solvent methyl isobutyl ketone and methanol were distilled off from the residual liquid, followed by drying to obtain spherical silica fine particles.
To 100 g of dried spherical silica fine particles, 10 g of hexamethyldisilazane and 10 g of the compound of the following formula 1, which is a cyclic silazane, are added as a hydrophobizing agent at room temperature, and then heated to 110 ° C. for 3 hours. By reacting, the spherical silica fine particles were hydrophobized.
Subsequently, it heated under reduced pressure (6650 Pa) until it became 80 degreeC, the solvent was distilled off completely (distillation removal), and the hydrophobic spherical silica fine particle of manufacture example 1 was produced.

Example 1
83 parts of styrene as monovinyl monomer and 17 parts of n-butyl acrylate (calculation of the resulting copolymer Tg = 60 ° C.), 7 parts of carbon black (trade name: # 25B, manufactured by Mitsubishi Chemical Corporation) as a black colorant, 1 part of a positively chargeable charge control agent (styrene / acrylic resin, manufactured by Fujikura Kasei Co., Ltd., trade name: FCA-207P), 0.6 part of divinylbenzene as a crosslinkable polymerizable monomer, t- as a molecular weight regulator 1.9 parts of dodecyl mercaptan and 0.25 parts of a polymethacrylic acid ester macromonomer (manufactured by Toa Gosei Co., Ltd., trade name: AA6, Tg of the resulting polymer = 94 ° C.) as a macromonomer are stirred and mixed with a stirrer. Then, it was further uniformly dispersed by a media type disperser. Here, 5 parts of dipentaerythritol hexamyristate was added, mixed and dissolved as a release agent to obtain 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 above-described polymerizable monomer composition is charged into the magnesium hydroxide colloid dispersion obtained as described above at room temperature, and stirred until the droplets are stabilized, where t-butyl peroxy- is used as a polymerization initiator. After adding 6 parts of 2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O), using an in-line type emulsifying disperser (trade name: Ebara Milder, manufactured by Ebara Seisakusho), 15,000 rpm The high-shear stirring was performed for 10 minutes at a rotational speed to form droplets of the polymerizable monomer composition.

  A suspension (polymerizable monomer composition dispersion) in which droplets of the polymerizable monomer composition obtained as described above are dispersed is charged into a reactor equipped with a stirring blade and heated to 90 ° C. Warm to initiate the polymerization reaction. A dispersion obtained by mixing 1 part of methyl methacrylate (polymerizable monomer for shell) and 10 parts of ion-exchanged water in the reactor when the polymerization conversion rate reaches almost 100%, and ion exchange 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) -propionamide) dissolved in 20 parts of water (polymerization initiator for shell, manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086) 0 3 parts were added. Then, after maintaining at 90 degreeC for further 4 hours and continuing superposition | polymerization, it cooled to room temperature and obtained the aqueous dispersion of the colored resin particle.

To the aqueous dispersion of colored resin particles obtained above, sulfuric acid is added to adjust the pH to 6.0 or lower, acid washing is performed, dehydration is performed by filtration, and 500 parts of ion-exchanged water is added again to form a slurry again. Washed with water. Thereafter, similarly, dehydration and washing with water were repeated several times, and after dehydration by filtration, they were 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 / Dp) of 1.14, and an average circularity of 0.983.

  To 100 parts of the colored resin particles obtained as described above, as external additive A specified in the present invention, magnesium stearate fine particles (trade name: SPX-100F, manufactured by Sakai Chemical Industry Co., Ltd.) which are fatty acid alkaline earth metal salt particles. Number average primary particle size: 0.72 μm) 0.1 part, as external additive B specified in the present invention, hydrophobized spherical silica fine particles (manufactured by Denki Kagaku Kogyo, trade name: UFP-30H, number average) Primary particle size: 110 nm, sphericity: 1.13) 0.5 part, and silica fine particles hydrophobized as external additive C (trade name: TG-820F, manufactured by Cabot Corporation), number average primary particles Example: 0.5 part (diameter: 7 nm) was added, and the mixture was added 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.). 1 To prepare a positively chargeable toner for non-magnetic one-component developing electrostatic image, and subjected to the test.

(Example 2)
In Example 1, the type of the external additive A specified in the present invention was changed to lithium stearate particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name: SPL-100F, number average primary particle size: 0.71 μm), The toner of Example 2 in the same manner as in Example 1 except that the type and amount of external additive B specified in the present invention were changed to 0.7 part of the hydrophobic spherical silica fine particles prepared in Production Example 1. Was prepared and used for testing.

(Example 3)
In Example 1, the type of the external additive B specified in the present invention was changed to hydrophobic silica fine particles (trade name: X-24-9163A, manufactured by Shin-Etsu Chemical Co., Ltd., number average primary particle size: 140 nm, The degree of sphericity was changed to 1.12), and the type of external additive C was changed to hydrophobized silica fine particles (trade name: TG-7120F, number average primary particle size: 22 nm, manufactured by Cabot Corporation). Except for this, the toner of Example 3 was produced in the same manner as in Example 1, and was subjected to the test.

Example 4
In Example 3, the type of external additive B specified in the present invention was changed to hydrophobic silica fine particles (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KMPX100, number average primary particle size: 100 nm, sphericity: 1 The toner of Example 4 was prepared in the same manner as in Example 3 except that it was changed to.

(Example 5)
In Example 1, the type of external additive A specified in the present invention was changed to lithium stearate particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name: SPL-100F, number average primary particle size: 0.71 μm). Except for the above, the toner of Example 5 was produced in the same manner as in Example 1, and was subjected to the test.

(Comparative Example 1)
In Example 1, a toner of Comparative Example 1 was produced in the same manner as in Example 1 except that the external additive A specified in the present invention was not added, and was subjected to the test.

(Comparative Example 2)
In Example 1, the toner of Comparative Example 2 was prepared in the same manner as in Example 1 except that the external additive B specified in the present invention was not added and the amount of the external additive C was changed to 1.0 part. Was prepared and used for testing.

(result)
Table 1 shows the test results of the toners produced in each Example and Comparative Example.

(Summary of results)
From the test results described in Table 1, the following can be understood.
The toner of Comparative Example 1 was caused by not using the external additive A specified in the present invention as an external additive, and the toner of Comparative Example 2 was an external additive specified in the present invention as an external additive. Due to the fact that additive B was not used, initial fog was likely to occur, it was difficult to maintain fine line reproducibility, and the toner had poor durability printability.

  On the other hand, the toners of Examples 1 to 5 were caused by using specific amounts of external additive A and external additive B specified in the present invention as external additives, respectively, even in a low temperature and low humidity environment. In addition, there is little initial fogging and excellent initial printing performance, and even if continuous printing of a large number of sheets is performed, fine line reproducibility is maintained, and even in a high temperature and high humidity environment, image quality deterioration due to fogging or the like hardly occurs. The toner has excellent durability printing performance.

Claims (3)

In a positively chargeable toner for developing an electrostatic charge image containing a binder resin, a colorant, and a colored resin particle comprising a charge control agent, and an external additive,
As the external additive, including external additive A and external additive B,
The external additive A is a fatty acid alkali metal salt particle or fatty acid alkaline earth metal salt particle having a number average primary particle size of 0.1 to 1 μm, and the fatty acid alkali metal salt particle or fatty acid alkaline earth metal. The content of the salt particles is 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the colored resin particles,
The external additive B is spherical silica fine particles having a number average primary particle size of 40 to 200 nm and a sphericity of 1 to 1.3, and the content of the spherical silica fine particles is 100 parts by weight of colored resin particles. A positively chargeable toner for developing an electrostatic charge image, characterized by being 0.2 to 2 parts by weight based on the weight of the toner. As the external additive, further includes an external additive C,
The external additive C is silica fine particles having a number average primary particle size of 5 to 25 nm, and the content of the silica fine particles is 0.2 to 2 parts by weight with respect to 100 parts by weight of the colored resin particles. The positively chargeable toner for developing an electrostatic image according to claim 1.   3. The positively chargeable toner for developing an electrostatic charge image according to claim 1, wherein the colored resin particles have an average circularity of 0.96 to 0.995. 4.