JP2009237274A - Positively charged toner for developing electrostatically charged image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide positively charged toner for developing electrostatically charged image capable of coping with even a toner supply type image forming device, achieving excellent stability in charging of toner when supplying the toner and satisfactory rising performance of charging, preventing the occurrence of initial fogging and filming on a photosensitive body, supplying stable positive charging to toner particles with age, and preventing the occurrence of deterioration of quality of image due to fogging and providing excellent durability to printing even after many sheets are continuously printed. <P>SOLUTION: This positively charged toner for developing electrostatically charged image contains a binding resin, a coloring agent, coloring resin particles prepared by including a positive charging controlling agent, and an external additive agent. The external additive agent contains melamine cyanurate particles having average diameter of primary particle of 0.05-1.5 μm per particle, and the content of the melamine cyanurate particles is 0.01-0.5 wt.pts. for 100 wt.pts. of coloring 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 that can be applied to a toner replenishing type image forming apparatus.

  An image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and an electrostatic printing apparatus forms a desired image by developing an electrostatic latent image formed on a photoreceptor with toner for developing an electrostatic image. The method is widely implemented and applied to copiers, printers, facsimiles, and multi-function machines.

  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. Then, the electrostatic latent image is developed using toner, and the toner image is transferred to a recording material such as paper as necessary, and then fixed by heating or the like to obtain a copy.

In recent years, as a toner used for development, a positively chargeable toner corresponding to a positively charged system is preferably used from the viewpoint of suppressing the generation of ozone and obtaining good chargeability.
The toner used for development is generally mixed with external additives such as inorganic fine particles and organic fine particles together with colored resin particles constituting the toner for the purpose of improving charging stability, fluidity, durability and the like. By stirring, an external additive is adhered and added (external addition) to the surface of the colored resin particles.

  In a toner obtained using a conventional external additive, in the process of performing continuous printing of a large number of sheets, due to mechanical stress in the developing device (increased number of contact between toner particles due to stirring, etc.), etc., The external additive is embedded in the surface of the toner particles and / or released (desorbed) from the surface of the toner particles, the function as the external additive is reduced, and the toner has a stable chargeability (charging stability) over time. It becomes difficult to impart to the particles.

  In addition, the toner particles in which the external additive is buried and the external additive released (detached) from the surface of the toner particle may damage the photoconductor or cause the toner particles to adhere to the surface of the photoconductor (filming phenomenon). As a result, the image quality is liable to be deteriorated due to fog or the like, and the printing performance such as lowering the printing durability of the toner is adversely affected.

  For this reason, in the process of performing continuous printing of a large number of sheets, even if the number of contact between the toner particles by stirring or the like increases in the developing device, problems such as embedding and / or releasing of the external additive do not occur, Development of a toner capable of maintaining a state in which an external additive is suitably attached over time and imparting stable chargeability (charge stability) to toner particles is desired.

According to the development of the toner, it can be applied to a replenishment type image forming apparatus.
The toner used in the conventional image forming apparatus has been replaced by a replacement method in which the cartridge is replaced when the remaining toner is low, but recently, the remaining toner has been reduced due to environmental and cost requirements. There is a need for a toner that can be used for an image forming apparatus that can supply new toner (new toner) to the toner (residual toner).

  In the above-described replenishing type image forming apparatus, the toner in the initial stage exhibits good charge stability, fluidity, and durability because the external additive is uniformly attached to the surface of the toner particles. However, the residual toner after the continuous printing of a large number of sheets is embedded and / or released due to mechanical stress in the developing device, etc. Property) to the toner particles.

  When a new toner is replenished to the remaining toner, toners having different charge states on the particle surface mix with each other, resulting in charge fluctuations, resulting in poor charge stability. There is a problem that the printing performance is adversely affected, such as initial fogging and filming on the photosensitive member.

  For this reason, the state in which the external additive is suitably attached to the surface of the colored resin particles of the residual toner is maintained over time, and a stable charging property (charging stability) is imparted to the toner particles (residual toner). It is desired to develop a toner that hardly changes in charging when replenishing new toner and can be applied to a replenishing type image forming apparatus.

  In Patent Document 1, among melamine cyanurates conventionally used as a flame retardant material, melamine cyanurate powder having a specific particle size (volume average particle size of 3 to 9 μm) is used as a toner, and 100 wt. An electrophotographic toner obtained by adding 0.1 to 2.0 parts by weight with respect to parts and externally adding is disclosed.

  However, the toner for electrophotography disclosed in Patent Document 1 only uses melamine cyanurate powder for the purpose of improving cleaning properties, and prevents poor cleaning of the photoreceptor and causes filming. Although it is considered to be a difficult toner, it does not have such a high charging performance that it can be applied to a replenishing type image forming apparatus.

JP 2006-317489 A

  The object of the present invention is also compatible with a toner replenishing type image forming apparatus, and has excellent toner charging stability, good charge rising property, little initial fogging, and less filling on a photoconductor. For electrostatic charge image development that can impart positively stable chargeability to toner particles over time, hardly deteriorates in image quality due to fog, etc. The object is to provide a positively chargeable toner.

  The inventors of the present invention have intensively studied to achieve the above object, and as a result, by using a specific amount of melamine cyanurate particles having a specific particle size as an external additive, charge rising can be performed at the initial printing immediately after toner replenishment. As a result, the initial fog is small, filming to the photoconductor hardly occurs, and a stable positive charging property can be imparted to the toner particles over time. It has been found that image quality is hardly deteriorated and printing durability is excellent, and the present invention has been completed based on these findings.

That is, 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 positive charge control agent, and an external additive. In toner,
The external additive contains melamine cyanurate particles having a number average primary particle size of 0.05 to 1.5 μm, and the content of the melamine cyanurate particles is 0.000 with respect to 100 parts by weight of the colored resin particles. A positively chargeable toner for developing an electrostatic image, characterized in that the amount is from 01 to 0.5 parts by weight.

  According to the present invention as described above, it can be applied to a toner replenishing type image forming apparatus, and when toner is replenished, the toner has excellent charging stability and good charge rising property. Filming on the body is unlikely to occur, and a stable positive charging property can be imparted to the toner particles over time. Therefore, even when multiple sheets are printed continuously, image quality is not easily deteriorated due to fog or the like, and printing durability is excellent. Further, a positively chargeable toner for developing an electrostatic image is provided.

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 positive charge control agent, and an external additive. In
The external additive contains melamine cyanurate particles having a number average primary particle size of 0.05 to 1.5 μm, and the content of the melamine cyanurate particles is 0.000 with respect to 100 parts by weight of the colored resin particles. The content is from 01 to 0.5 parts by 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 positive charge control agent, and an external additive specified by the present invention.

  Specific examples of the binder resin include conventionally widely used resins such as polystyrene, styrene-butyl acrylate copolymer, polyester resin, and epoxy resin.

  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, other additions such as a polymerizable monomer, a colorant, a positive charge control agent, and a release agent as required The polymerizable monomer composition is prepared by mixing, dissolving or dispersing the product using a stirrer.

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 can be 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.

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 derivatives thereof. Aromatic divinyl compounds such as ethylene glycol dimethacrylate and ethylenically unsaturated carboxylic acid esters such as diethylene glycol dimethacrylate; divinyl compounds such as N, N-divinylaniline and divinyl ether; trimethylolpropane trimethacrylate and dimethylol A compound having three or more vinyl groups such as propanetetraacrylate; and the like. These crosslinkable polymerizable monomers may be used alone or in combination of two or more.
The crosslinkable polymerizable monomer is added at the stage of forming a droplet of the polymerizable monomer composition in the aqueous dispersion medium in the suspension step of obtaining the suspension in the next step (2). Also good.
In the present invention, it is desirable to use the crosslinkable polymerizable monomer in a proportion of usually 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. .

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.

  Examples of cyan colorants include compounds such as copper phthalocyanine pigments, derivatives thereof, and anthraquinone pigments. 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 azo pigments such as monoazo pigments and 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 monovinyl monomer.

In the present invention, a positive charge control agent is used to impart positive chargeability to the toner particles.
The positive charge control agent is not particularly limited as long as it is generally used as a positive charge control agent for toner. In the present invention, among the positive charge control agents, a polymerizable monomer or a binder is used. A positive charge control resin is preferably used because it is excellent in dispersibility and compatibility with the resin and can impart stable positive chargeability to the toner particles.
Examples of the positive charge control resin include FCA-161P (trade name, styrene / acrylic resin), FCA-207P (: trade name, styrene / acrylic resin), and FCA-201-PS (: Commercial products such as trade name, styrene / acrylic resin) can be used.
Other positive charge control agents include, for example, BONTRON N-01 (: trade name, nigrosine), BONTRON N-04 (: trade name, nigrosine), BONTRON N-07 (: trade name) manufactured by Orient Chemical Co., Ltd. , Nigrosine), and BONTRON P-51 (: trade name, quaternary ammonium salt) and the like can be used.
In the present invention, it is desirable to use the positive charge control agent in a proportion of usually 0.01 to 10 parts by weight, preferably 0.03 to 8 parts by weight with respect to 100 parts by weight of the monovinyl 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 wax such as paraffin, microcrystalline and petrolatum; mineral wax such as montan, ceresin and ozokerite; synthetic wax 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 weight part normally with respect to 100 weight part of monovinyl 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, 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.
The molecular weight modifier may be added at the stage of forming droplets of the polymerizable monomer composition in the aqueous dispersion medium in the subsequent step (2) in the suspension step of obtaining a suspension.
In the present invention, it is desirable to use the molecular weight modifier in a proportion of usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the monovinyl monomer.

(2) Suspension step for obtaining a suspension (droplet formation step)
(1) The polymerizable monomer composition obtained through the preparation process 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 forming droplets is, for example, an in-line type emulsifying disperser (manufactured by Ebara Seisakusho, trade name: Ebara Milder), and a high-speed emulsifying / dispersing machine (made by Tokushu Kika Kogyo Co., Ltd., trade name: T.-T K. homomixer MARK II type) can be used.

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 dispersion stabilizers, a dispersion stabilizer containing a metal hydroxide colloid that dissolves in an acid solution is preferably used, and magnesium hydroxide is more preferably used. The dispersion stabilizers can be used alone or in combination of two or more.
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 monovinyl 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 weight, more preferably 0.3 to 15 parts by weight, with respect to 100 parts by weight of the monovinyl monomer, and 1.0 to More preferably, it is 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.

In the present invention, the colored resin particles obtained by the polymerization step are used as a core layer, and a colored resin having a core-shell structure (also referred to as “capsule type”) obtained by forming a shell layer different from the core layer on the outer side thereof. It is preferable to use particles.
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 material having a higher softening point, thereby reducing the toner fixing temperature and preventing aggregation during storage. Can be taken.

  There is no restriction | limiting in particular as a method of manufacturing the colored resin particle which has the said core-shell structure, 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 colored resin particles having a core-shell structure by an in situ polymerization method 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. Colored resin particles having a core-shell structure 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 Polymerization start of water-soluble azo compounds such as ethyl) propionamide) and 2,2′-azobis (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); An agent can be mentioned.
The addition amount of the polymerization initiator for shell used in the present invention is preferably 0.1 to 30 parts by weight, and preferably 1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer for shell. More preferred.

  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) Washing, filtration, dehydration, and drying steps The aqueous dispersion of colored resin particles obtained by the above (3) polymerization step is carried out according to a conventional method, and a series of operations of washing, filtration, and dehydration are performed as necessary. Repeated several times, and the resulting solid is dried to obtain colored resin particles.

First, in order to remove the dispersion stabilizer remaining in the aqueous dispersion medium of the colored resin particles, washing is performed by adding an acid or an alkali to the aqueous dispersion of the colored resin particles.
When the dispersion stabilizer used is an acid-soluble inorganic compound, an acid is added to the aqueous dispersion of colored resin particles, while the dispersion stabilizer used is an alkali-soluble inorganic compound. In some cases, an alkali is added to the aqueous dispersion of colored resin particles.

  When an acid-soluble inorganic compound is used as the dispersion stabilizer, it is preferable to add an acid to the aqueous dispersion of colored resin particles and perform acid washing until the pH is 6.5 or lower. As the acid added in the acid washing, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; organic acids such as formic acid and acetic acid; and the like can be used. Among these, sulfuric acid is particularly preferable because the removal efficiency of the dispersion stabilizer is good and the burden on the toner production facility is small.

  After washing with an acid or alkali added to the aqueous dispersion of colored resin particles obtained by the polymerization step, filtration and separation are performed, and ion-exchanged water is added to the resulting solid to reslurry. Then, washing treatment (washing, filtration, dehydration) with a washing solution such as water is repeated several times, and the solid content obtained is dried to obtain colored resin particles.

  The method for the cleaning treatment and the drying treatment is not particularly limited, and various known methods can be used. Examples of the apparatus used for the washing treatment include peeler centrefuge, siphon peeler centrefuge, and the like. Examples of the method used in the method include vacuum drying, air flow drying, and a super dryer.

(B) Pulverization method When the pulverization method is used to produce colored resin particles, the following process is performed.
First, other additives such as a binder resin, a colorant, a positive charge control agent, and a release agent added as necessary are mixed in a mixer such as a ball mill, a V-type mixer, a Henschel mixer (: commodity) Name), 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, and 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 positive charge control agent used in the pulverization method, and a release agent added as necessary are listed in the above (A) suspension polymerization method. Things can be used. Further, the colored resin particles obtained by the pulverization method are preferably used as colored resin particles having a core-shell structure by a method such as an in situ polymerization method, similarly to the colored resin particles obtained by the suspension polymerization method (A) described above. .

(5) Colored resin particles Colored resin particles are obtained by the above-described (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 those having a core-shell structure and those not.

  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 1.00, more preferably from 0.97 to 1.00, from the viewpoint of forming a high quality image. More preferably, it is 1.00.
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 a particle group having a circle-equivalent diameter of 0.4 μm or more was obtained 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 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.

(6) External Addition Step The colored resin particles obtained by the above-mentioned (A) polymerization method or (B) pulverization method are mixed and stirred together with the external additive specified in the present invention, to the surface of the colored resin particles. The external additive can be uniformly adhered and added (external addition) to obtain desired toner particles.
The toner particles may be mixed and stirred together with carrier particles (such as ferrite and iron powder) to form a two-component developer.

  The method for adhering and adding (external addition) the external additive specified in the present invention to the surface of the colored resin particles is not particularly limited. For example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (: Product name, manufactured by Kawada Mfg. Co., Ltd., Q mixer (: product name, manufactured by Mitsui Mining Co., Ltd.), Mechano Fusion System (: product name, manufactured by Hosokawa Micron Co., Ltd.), Mechano Mill (: product name, manufactured by Okada Seiko Co., Ltd.), and Nobilta ( : A trade name, manufactured by Hosokawa Micron Corporation) and the like.

The external additive specified in the present invention is melamine cyanurate particles having a specific particle size.
Here, “melamine cyanurate” means that a melamine molecule (formula 1 below) and a cyanuric acid molecule (formula 2 below) are arranged in a plane by hydrogen bonds, and the chemical formula (C ₆ H ₉ N ₉ O ₃ ) _n It refers to a compound represented by, for example, a structural formula such as Formula 3 or Formula 4 below.
In addition, as represented by the following formula 2, cyanuric acid has two tautomers, an enol type and a keto type, and the keto type cyanuric acid is generally referred to as isocyanuric acid.

  In the present invention, the production method of the melamine cyanurate particles is not particularly limited as long as it can be produced so as to have a specific particle diameter, and can be produced by a conventionally known method, for example, JP-A-5-310716. And JP-A-7-149739 and JP-A-7-224049.

  As an example of a method for producing melamine cyanurate particles, melamine powder and cyanuric acid were charged at a predetermined mixing ratio into a device capable of mixing and stirring, and the temperature inside the tank was raised to a predetermined temperature while mixing. Then, when water is gradually added to the tank while stirring and neutralization reaction is performed, a white precipitate is generated, and the precipitate is filtered and dried and granulated. The method of obtaining the melamine cyanurate particle | grains of this is mentioned.

  In the present invention, the melamine cyanurate particles specified as an external additive can also be obtained as a commercial product, for example, STABACE MC-5F manufactured by Sakai Chemical Industry Co., Ltd. (: trade name, number average primary particle size: 0). .47 μm) and STABIACE MC-5S (trade name, number average primary particle size: 0.53 μm).

  In the present invention, the number average primary particle size of the melamine cyanurate particles specified as the external additive is 0.05 to 1.5 μm, preferably 0.2 to 1 μm, more preferably 0.3 to 0.00. 8 μm.

  When the number average primary particle size of the melamine cyanurate particles is less than the above range, sufficient charge rising property may not be obtained at the time of toner replenishment, and it may take time to eliminate the initial fog. On the other hand, when the number average primary particle size of the melamine cyanurate particles exceeds the above range, not only the charge rising property at the time of toner replenishment but also the filming and fogging on the photoreceptor during continuous printing, etc. In some cases, the image quality may be deteriorated due to.

  In the present invention, the content of the melamine cyanurate particles specified as the external additive is 0.01 to 0.5 parts by weight, preferably 0.01 to 0.3 parts per 100 parts by weight of the colored resin particles. More preferably, it is 0.02 to 0.2 parts by weight.

  When the content of the melamine cyanurate particles is less than the above range, not only the charge rising property failure at the time of toner replenishment but also the image quality deterioration due to filming on the photoreceptor and fogging during continuous printing. May be prone to being caused. On the other hand, when the above range is exceeded, sufficient charge rising property may not be obtained at the time of toner replenishment, and it may take time to eliminate the initial fog.

In the present invention, the melamine cyanurate particles specified as the external additive are preferably hydrophobized from the viewpoint of improving dispersibility.
Representative examples of the hydrophobizing agent include silane coupling agents, silicone oils, fatty acids, and fatty acid metal salts. Among these, a silane coupling agent and silicone oil are preferably used because they have a high effect of improving dispersibility.

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 can be used alone or in combination of two or more.

In the present invention, the method for hydrophobizing melamine cyanurate particles specified as an external additive is not particularly limited as long as it is a conventionally known method, and examples thereof include a dry method and a wet method.
Specifically, a dry method in which a hydrophobizing agent is dropped or sprayed while stirring the melamine cyanurate particles at a high speed; the hydrophobizing agent is dissolved in an organic solvent, and the melamine cyanurate particles are stirred while the organic solvent is stirred. And a wet method in which is added.

  In the present invention, in addition to the external additive (melamine cyanurate particles) specified in the present invention described above, as other external additives, silica fine particles (A) and / or silica fine particles having different particle diameter ranges ( B) is preferably used, and silica fine particles (A) and silica fine particles (B) are more preferably used.

The number average primary particle size of the silica fine particles (A) is preferably 5 to 18 nm, more preferably 6 to 16 nm, and further preferably 7 to 14 nm.
When the number average primary particle size of the silica fine particles (A) is less than the above range, the silica particles are easily embedded in the surface of the toner particles, and during printing, image quality is liable to be deteriorated due to fog and the like. May have adverse effects.

The number average primary particle size of the silica fine particles (B) is preferably 20 to 80 nm, more preferably 25 to 65 nm, and even more preferably 30 to 50 nm.
When the number average primary particle size of the silica fine particles (B) exceeds the above range, the fluidity of the toner is lowered, and the image quality is liable to be deteriorated due to fog or the like during printing, which adversely affects the printing performance. There is a case.

  The silica fine particles (A) can also be obtained as a commercial product, for example, HDK2150 (: trade name, number average primary particle size: 12 nm) manufactured by Clariant, R504 (: trade name, number manufactured by Nippon Aerosil Co., Ltd.). Average primary particle size: 12 nm), RA200HS manufactured by Nippon Aerosil Co., Ltd. (trade name, number average primary particle size: 12 nm), MSP-012 manufactured by Teika Co., Ltd. (: product name, number average primary particle size: 16 nm), and It is commercially available as MSP-013 (trade name, number average primary particle size: 12 nm) manufactured by Teika.

  Silica fine particles (B) can also be obtained as a commercial product. For example, NA50Y manufactured by Nippon Aerosil Co., Ltd. (: trade name, number average primary particle size: 35 nm), VPNA50H manufactured by Nippon Aerosil Co., Ltd. (: trade name, Number average primary particle size: 40 nm), Teica MSP-011 (: trade name, number average primary particle size: 30 nm), and Clariant H05TA (: trade name, number average primary particle size: 50 nm) It is commercially available.

The content of the silica fine particles (A) is preferably 0.1 to 3 parts by weight, more preferably 0.2 to 2.5 parts by weight with respect to 100 parts by weight of the colored resin particles. More preferably, it is 3 to 2 parts by weight.
When the content of the silica fine particles (A) is less than the above range, fluidity may be reduced and image blurring may occur. On the other hand, when the content of the silica fine particles (A) exceeds the above range, fixing failure may occur.

The content of the silica fine particles (B) is preferably 0.1 to 3 parts by weight, more preferably 0.3 to 2.5 parts by weight with respect to 100 parts by weight of the colored resin particles. More preferably, it is 4 to 2 parts by weight.
When the content of the silica fine particles (B) is less than the above range, the charge amount may decrease and fog may occur. On the other hand, when the content of the silica fine particles (B) exceeds the above range, fluidity may be lowered and image blurring may occur.

  In the present invention, in addition to the external additive (melamine cyanurate particles) specified in the present invention described above, as other external additives, silica fine particles (A) and / or silica fine particles having different particle diameter ranges ( When used in combination with B), the colored resin particles and all external additives can be added to an apparatus capable of mixing and stirring, and the external addition process can be performed at once, but a suitable external addition process is performed. Therefore, first, after adding the colored resin particles and the external additive having a relatively large particle diameter to an apparatus capable of mixing and stirring and performing the external addition treatment, the external additive having a relatively small particle diameter is added. Further, it is preferable to carry out the external addition treatment.

  In the present invention, both the silica fine particles (A) and the silica fine particles (B) preferably used as other external additives are preferably hydrophobized, and the external additive (melamine shear) specified in the present invention described above is preferably used. Hydrophobic treatment can be performed in the same manner as in the case of (nurate particles).

(7) Toner The toner obtained through the above steps (1) to (6) uses a specific amount of melamine cyanurate particles having a specific particle size as an external additive, so that the initial printing immediately after toner replenishment is performed. The charge rising property is good, the initial fog is small, the filming on the photoconductor hardly occurs, and the toner particles can be given a positive charging property that is stable over time. This is a positively chargeable toner that hardly deteriorates in image quality due to fog or the like and has excellent printing durability.

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.

<Test method>
(1) Number average primary particle diameter of external additive The external additive was photographed with a transmission electron micrograph, and the photograph was taken with an image processing analyzer (trade name: Luzex IID, manufactured by Nireco Corporation). The area ratio of the sample was 2% at the maximum and the total number of treated particles was 100. The actual projected area of the particles was analyzed, the equivalent circle diameter was calculated, and the arithmetic average value was obtained.

(2) 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 alkylbenzene sulfonic acid aqueous solution (manufactured by Fuji Film Co., Ltd., trade name: Drywell) was added as a dispersant. 10-30 ml of Isoton II is further added to the beaker and dispersed for 3 minutes with a 20 W ultrasonic disperser. The volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles were measured under the conditions of 100 μm, medium; Isoton II, number of measured particles; 100,000 particles, 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 an average of the circularity.
Formula 1:
(Circularity) = (Perimeter of circle equal to projected area of particle) / (Perimeter of particle projection image)

(3) Charging characteristics of toner (3-1) Initial charge amount measurement test Commercially available non-magnetic one-component development type printer (manufactured by Brother Industries, trade name: HL-5240 (30 ppm), printing speed: A4 size 30 Sheet / minute), the toner cartridge in the developing device was filled with toner, 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%), printing 5 sheets at 5% print density in the same environment, then developing roller The toner carried on the surface is sucked using a suction-type charge measuring device (trade name: 210HS-2A, manufactured by Trek Japan) to measure the initial charge amount of the toner, and the charge amount per unit weight of the toner Calculated in terms of Q / M (μC / g).
A toner having a charge amount of +5 to 100 (μC / g) can be evaluated as having a charge amount appropriate for a positively chargeable toner.

(4) Toner printing characteristics (4-1) Durability printing test For the durability printing test, the same printer as in the above (3-1) initial charge measurement test was used. Put. After leaving for 24 hours in a normal temperature and humidity (N / N) environment with a temperature of 23 ° C and a humidity of 50%, continuous printing is performed up to 12,000 sheets at a 5% print density in the same environment. The fog value was measured.
The fog value was measured as follows.
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 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: NDW-1D, manufactured by Nippon Denshoku Co., Ltd.). The whiteness (A) was measured and the whiteness difference (B−A) was defined as the fog value. Smaller values indicate better fogging.
The number of continuously printed sheets capable of maintaining an image quality with a print density of 1.3% or more and a fog value of 3.0 or less was counted.
In Table 1, the number of fog occurrences described as “12,000 <” indicates that the image quality with a fog value of 3 or less could be maintained at the time of 12,000 sheets.

(4-2) Printing test during replenishment The printing test during replenishment is carried out after the end of the above (4-1) endurance printing test, leaving 30 g of residual toner in the developing device, replenishing 100 g of new toner and white solid printing ( The print density is 0%), the printer is stopped in the middle of white solid printing, and the toner in the non-image area on the developed photoreceptor is treated with adhesive tape (manufactured by Sumitomo 3M, trade name: Scotch Mending Tape 810-). After adhering to 3-18), it was 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: NDW-1D, 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 fogging.
At the time of printing immediately after toner replenishment, the fog value is 3 or more, but the fog value gradually decreases as printing is repeated. The number of sheets when the fog value became 3 or less by printing was counted, and the number of sheets where the initial fog disappeared immediately after replenishment was counted.

(4-3) Filming test For the filming test, the same printer as the above (3-1) initial charge amount measurement test was used, and the toner cartridge of the developing device was filled with toner, and then the printing paper was set. did.
After standing for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), a print test is performed at 1% print density in the same environment, and half every 500 sheets. Tone printing (printing density 50%) was performed to confirm the presence or absence of filming on the photoreceptor.
The number of sheets when a white blurred image was confirmed for the first time in a halftone image was counted as the number of filming occurrences, and a printing test was conducted up to a maximum of 10,000 sheets.
In Table 1, the number of filming occurrences described as “10,000 <” indicates that no filming occurred on the photoconductor at the time of 10,000 sheets.

<Toner production method>
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 positive charge control resin (made by Fujikura Kasei Co., Ltd., trade name: FCA-207P, styrene / acrylic resin) as a positive charge control agent, 0.6 part of divinylbenzene as a crosslinkable polymerizable monomer, as a molecular weight regulator 1.9 parts of t-dodecyl mercaptan and 0.25 parts of a polymethacrylic acid ester macromonomer (manufactured by Toa Gosei Co., Ltd., trade name: AA6) as a macromonomer were stirred and mixed with a stirrer, and then a media type dispersing machine. To uniformly disperse. Here, 5 parts of dipentaerythritol hexamyristate was added, mixed and dissolved as a release agent to obtain a polymerizable monomer composition for core.

  On the other hand, at room temperature (25 ° C.), an aqueous solution obtained by dissolving 10.2 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, sodium hydroxide (alkali metal hydroxide) in 50 parts of ion-exchanged water. Salt) An aqueous solution in which 6.2 parts were dissolved was gradually added with stirring to prepare a magnesium hydroxide colloid (hardly water-soluble metal hydroxide colloid) dispersion.

  The above-mentioned magnesium hydroxide colloid dispersion is charged with the core polymerizable monomer composition at room temperature (25 ° C.), and the generated coarse droplets are stabilized using a stirring device equipped with a stirring blade. And then adding 6 parts of t-butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) as a polymerization initiator, and then adding an in-line type emulsion disperser (Ebara Corporation) (Manufactured, product name: Ebara Milder) was dispersed by high-speed shearing stirring at a rotational speed of 15,000 rpm for 10 minutes to form droplets of the polymerizable monomer composition for the core.

  The dispersion liquid (suspension) of the polymerizable monomer composition for core formed in the above-described droplets was put into a reactor equipped with a stirring blade and heated to 90 ° C. 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 ions 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) -propionamide) dissolved in 20 parts of exchange water (polymerization initiator for shell, manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086) 0.3 parts were added. Thereafter, the reaction was further continued at 90 ° C. for 4 hours, and then cooled to room temperature to obtain an aqueous dispersion of colored resin particles having a core-shell structure.

  A 10% dilute sulfuric acid aqueous solution (an aqueous solution containing 10% by weight of sulfuric acid) was added dropwise to the aqueous dispersion of colored resin particles obtained as described above with stirring at room temperature (25 ° C.), and the pH was 6.0 or less. Acid cleaning was performed until Next, filtration separation is performed, 500 parts of ion-exchanged water is added to the obtained solid content to make a slurry again, and water washing treatment (washing, filtration, dehydration) is repeated several times, followed by filtration separation, 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 / Dp) of 1.14, and an average circularity of 0.983.

  To 100 parts of the colored resin particles obtained as described above, melamine cyanurate particles (manufactured by Sakai Chemical Industry Co., Ltd., trade name: STABIACE MC-5S, number average primary particle size: 0.53 μm) as an external additive specified in the present invention. And 0.1 part of hydrophobized silica fine particles (A) (manufactured by Clariant, trade name: HDK2150, number average primary particle size: 12 nm), 0.9 parts, and hydrophobic Silica fine particles (B) (trade name: NA50Y, number average primary particle size: 35 nm) manufactured by Nippon Aerosil Co., Ltd. were added, and a high-speed stirrer (trade name: Henschel mixer, manufactured by Mitsui Mining Co., Ltd.) The toner was mixed and stirred at a peripheral speed of 30 m / s for 6 minutes for external addition to produce the positively chargeable toner of Example 1 and used for the test.

(Example 2)
In Example 1, the type of melamine cyanurate particles was changed to STABIACE MC-5F (trade name, manufactured by Sakai Chemical Industry Co., Ltd., number average primary particle size: 0.47 μm). Thus, a positively chargeable toner of Example 2 was prepared and used for the test.

(Example 3)
In Example 2, the positively chargeable toner of Example 3 was prepared and used for the test in the same manner as in Example 2 except that the silica fine particles (A) were not added.

Example 4
In Example 2, the positive charge of Example 4 was changed in the same manner as Example 2 except that the type of the positive charge control agent was changed to BONTRON N-01 (trade name, manufactured by Orient Chemical Industries, Nigrosine). Toner was prepared and used for testing.

(Comparative Example 1)
In Example 4, a positively chargeable toner of Comparative Example 1 was produced in the same manner as in Example 4 except that the melamine cyanurate particles were not added, and used for the test.

(Comparative Example 2)
In Example 4, except that the type and amount of melamine cyanurate particles were changed to 0.2 parts of MC-6000 (trade name, manufactured by Nissan Chemical Industries, Ltd., number average primary particle size: 2 μm). In the same manner as in Example 4, a positively chargeable toner of Comparative Example 2 was prepared and used for the test.

(Comparative Example 3)
A positively chargeable toner of Comparative Example 3 was produced in the same manner as in Example 2 except that the amount of melamine cyanurate particles added was changed to 0.7 part in Example 2, and was subjected to the test.

(Comparative Example 4)
In Example 4, instead of adding melamine cyanurate particles, Eposter S (: trade name, manufactured by Nippon Shokubai Co., Ltd., number average primary particle size: 0.2 μm, melamine resin particles obtained from melamine and formaldehyde) 0.2 A positively chargeable toner of Comparative Example 4 was produced in the same manner as in Example 4 except that the part was added, and used for the test.

<Result>
Table 1 shows the test results of the positively chargeable toners produced in each example and comparative example.
The notes in Table 1 are as follows.
* 1: Although described in the column of melamine cyanurate particles for convenience, melamine resin particles obtained from melamine and formaldehyde other than those specified in the present invention

<Summary of results>
From the test results described in Table 1, the following can be understood.
The positively chargeable toner of Comparative Example 1 was obtained because the melamine cyanurate particles specified in the present invention were not used, and although an appropriate charge amount was obtained as the positively chargeable toner, the printing durability was inferior. It was a toner that took a long time to eliminate the initial fog generated at the time of initial printing immediately after replenishment, was poor in charge rising property, and was liable to cause filming on the photoreceptor.

  Although the positively chargeable toner of Comparative Example 2 used melamine cyanurate particles exceeding the particle size range specified in the present invention, an appropriate charge amount was obtained as a positively chargeable toner, but printing durability The toner is inferior in properties, takes time to eliminate the initial fog generated at the time of initial printing immediately after the replenishment of toner, has poor charge rising property, and easily forms filming on the photoreceptor.

  The positively chargeable toner of Comparative Example 3 was caused by the use of melamine cyanurate particles exceeding the range of the addition amount specified in the present invention, and fogging occurred from the beginning in the durability print test. No filming test was performed.

  The positively chargeable toner of Comparative Example 4 was caused by the use of melamine resin particles other than those specified in the present invention, and fogging occurred relatively early in the durability printing test. The test was not conducted.

  On the other hand, the positively chargeable toners of Examples 1 to 4 are obtained by using a specific amount of the melamine cyanurate particles specified in the present invention as an external additive, so that the charge amount appropriate for the positively chargeable toner is used. It is a toner that has excellent printing durability, does not require much time to eliminate the initial fog that occurs during initial printing immediately after toner replenishment, has excellent charge rise characteristics, and does not easily cause filming on the photoreceptor. .

Claims (4)

In a positively chargeable toner for developing an electrostatic charge image containing a binder resin, a colorant, and colored resin particles comprising a positive charge control agent, and an external additive,
The external additive contains melamine cyanurate particles having a number average primary particle size of 0.05 to 1.5 μm, and the content of the melamine cyanurate particles is 0.000 with respect to 100 parts by weight of the colored resin particles. A positively chargeable toner for developing an electrostatic charge image, characterized by being from 01 to 0.5 parts by weight.   The positively chargeable toner for developing an electrostatic charge image according to claim 1, wherein the positive charge control agent is a positive charge control resin.   3. The positively chargeable toner for developing an electrostatic charge image according to claim 1, wherein the external additive further contains silica fine particles (A) having a number average primary particle diameter of 5 to 18 nm.   The positive electrode for electrostatic charge image development according to any one of claims 1 to 3, wherein the external additive further contains silica fine particles (B) having a number average primary particle size of 20 to 80 nm. Chargeable toner.