JP6589538B2 - Toner for electrostatic latent image development - Google Patents

Description

  The present invention relates to an electrostatic latent image developing toner. More specifically, the present invention is based on abrasion of the external additive in the cleaning portion while maintaining charging performance even when images with a high printing rate are continuously printed under severe use environments such as high temperature and high humidity. The present invention relates to an electrostatic latent image developing toner capable of suppressing the occurrence of image defects due to local wear of a photoreceptor.

  Printers and multi-function machines that employ an electrophotographic system are required to stably output a wide variety of printed materials such as small-lot printed materials and printed images of full-color images over a long period of time.

  In addition, the printers and multifunction devices described above are rapidly spreading in emerging countries such as BRICs such as Brazil, Russia, India, and China, so they may be used in higher temperature and humidity environments. is assumed. For this reason, stable output is required even in a high temperature and high humidity environment. In particular, when images with a high printing rate are output continuously, it is necessary not only to stabilize the toner charge amount but also to reliably clean the toner remaining after transfer (hereinafter also referred to as “transfer residual toner”). It becomes.

Conventionally, it has been proposed to stabilize the charge amount even in a high-temperature and high-humidity environment by using silica particles having alkylalkoxysilane having a relatively long carbon number on the surface (see, for example, Patent Document 1). ).
However, silica particles having an alkylalkoxysilane having a relatively long carbon number on the surface have high adhesion, and when used in toner, the fluidity of the toner tends to be reduced, and the rise of charge is delayed. As a result, when images having a high printing rate are continuously printed, the charge amount does not rise and the charge amount is low. Furthermore, silica particles modified with alkylalkoxysilane having a relatively long carbon number on the surface have high adhesiveness and thus low fluidity, and are stored in a damming layer in the cleaning unit. In such a state, the external additive may come off as a strongly aggregated mass and damage the surface of the photoreceptor.
In addition, the transfer residual toner can be reliably cleaned by using a large-diameter external additive. However, when a small-diameter external additive is used, a small-diameter external additive is added to the cleaning layer at the cleaning section. The agent cannot be damped up, resulting in abrasion. As a result, the surface of the photoreceptor is locally depleted, and stripes (image defects) with different densities may occur on the image. For this reason, in order to use a small-diameter external additive, further improvement is necessary.

JP 2013-235046 A

  The present invention has been made in view of the above-described problems and circumstances, and its solution is to maintain charging performance even when images with a high printing rate are continuously printed under severe use environments such as high temperature and high humidity. On the other hand, it is an object to provide a toner for developing an electrostatic latent image that can suppress the occurrence of image defects due to local wear (uneven wear) of the photoreceptor due to the external additive being scraped off in the cleaning section.

In order to solve the above-mentioned problems, the present inventor, in the process of examining the cause of the above-mentioned problems, two types of silica, silica particles hydrophobized with alkylalkoxysilane and silica particles hydrophobized with silazane. By using particles in combination, the stability of cleaning when continuously printing images with a high printing rate (suppression of uneven photoconductor wear by reducing the wear-through of external additives) and the stability of charge in a high-temperature, high-humidity environment As a result, the present invention has been found.
That is, the said subject which concerns on this invention is solved by the following means.

1. An electrostatic latent image developing toner containing toner particles comprising toner base particles containing at least a colorant and an external additive attached to the surface of the toner base particles,
As the external additive, at least,
Silica particles A having a number average primary particle diameter in the range of 10 to 50 nm and hydrophobized with alkylalkoxysilane having a structure represented by the following general formula (1):
An electrostatic latent image developing toner comprising two types of silica particles, silica particles B having a number average primary particle diameter in the range of 10 to 50 nm and hydrophobized with silazane.
Formula (1) R ¹ —Si (OR ² ) ₃
R ¹ : a linear alkyl group having 12 to 16 carbon atoms which may have a substituent R ² : a methyl group or an ethyl group

  2. 2. The electrostatic latent image developing toner according to item 1, wherein the silazane is hexamethyldisilazane or hexaethyldisilazane.

  3. The first or second item further includes silica particles having a number average primary particle diameter in the range of 70 to 250 nm and an average circularity in the range of 0.850 to 0.950. Item 3. The electrostatic latent image developing toner according to item 2.

4). The toner base particles contain at least a binder resin, and
Item 4. The electrostatic latent image developing toner according to any one of Items 1 to 3, wherein the binder resin contains at least a crystalline resin.

By the above means of the present invention, even when an image with a high printing rate is continuously printed under severe use environment such as high temperature and high humidity, the charging performance is maintained, and the photosensitive material by the external additive is worn through the cleaning portion. It is possible to provide a toner for developing an electrostatic latent image that can suppress the occurrence of image defects due to local wear of the body.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

The present inventor made silica particles (number average primary particle size: 10 to 50 nm) hydrophobized with a specific alkylalkoxysilane and silica particles (number average primary particle size 10 to 50 nm) hydrophobized with silazane; In combination , silica particles hydrophobized with alkylalkoxysilane can be formed into dense aggregates (damping layers), and silica particles hydrophobized with silazane adhere to it, resulting in fluidity. It is given and replaced moderately without storing. Thereby, it is possible to suppress uneven wear of the photoconductor while suppressing the scavenging of the external additive in the damming layer.
In addition, the degree of hydrophobicity can be increased by making the chain length of the alkyl group of silica particles hydrophobized with alkylalkoxysilane moderate, and silica particles hydrophobized with silazane are used in combination. By doing so, it is considered that the toner charge amount can be stabilized even if images having a fast charge rise and a high printing rate in a high temperature and high humidity environment are continuously printed.

The electrostatic latent image developing toner of the present invention is a toner for electrostatic latent image development containing toner particles comprising toner base particles containing at least a colorant and external additives attached to the surface of the toner base particles. Because
As the external additive, at least,
Silica particles A having a number average primary particle diameter in the range of 10 to 50 nm and hydrophobized with alkylalkoxysilane having a structure represented by the general formula (1);
The number average primary particle diameter is in the range of 10 to 50 nm and contains two types of silica particles, silica particles B hydrophobized with silazane.

  This feature is a technical feature common to or corresponding to the inventions according to claims 1 to 4.

  As an embodiment of the present invention, it is preferable that the silazane is hexamethyldisilazane or hexaethyldisilazane because a decrease in toner fluidity can be suppressed.

  In the present invention, it is dense that the number average primary particle diameter is in the range of 70 to 250 nm and the silica particles having an average circularity in the range of 0.850 to 0.950 are further contained. It is preferable because a damming layer can be formed, the suppression of frictional charging between the toner and the carrier can be avoided, and the occurrence of abrasion can be suppressed.

  In the present invention, if the toner base particles contain at least a binder resin and the binder resin contains at least a crystalline resin, the toner particles can be easily melted, and energy can be saved when fixing to a recording medium. It is preferable from the viewpoint of achieving.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Overview of electrostatic latent image developing toner>
The electrostatic latent image developing toner of the present invention is a toner for electrostatic latent image development containing toner particles comprising toner base particles containing at least a colorant and external additives attached to the surface of the toner base particles. In addition, as the external additive, at least the number average primary particle diameter was within a range of 10 to 50 nm and was hydrophobized with an alkylalkoxysilane having a structure represented by the following general formula (1) . It contains two types of silica particles: silica particles A and silica particles B having a number average primary particle diameter in the range of 10 to 50 nm and hydrophobized with silazane.
Formula (1) R ¹ —Si (OR ² ) ₃
R ¹ : a linear alkyl group having 12 to 16 carbon atoms which may have a substituent R ² : a methyl group or an ethyl group

[Toner particles]
The toner particles according to the present invention include toner base particles containing at least a colorant and external additives attached to the surface of the toner base particles.

<Toner base particles>
The toner base particles according to the present invention are not particularly limited as long as they contain a colorant, and known toners can be used. In particular, the toner base particles contain at least a binder resin, and the binder resin is at least crystalline. It is preferable to contain a functional resin.

<Colorant>
A known colorant can be used as the colorant.

  Specifically, examples of the colorant contained in the yellow toner include C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Pigment yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, and the like. These can be used alone or in combination of two or more. Among these, C.I. I. Pigment Yellow 74 is preferable.

  The content of the colorant contained in the yellow toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Specifically, examples of the colorant contained in the magenta toner include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, and the like. These can be used alone or in combination of two or more. Among these, C.I. I. Pigment Red 122 is preferable.

  The content of the colorant contained in the magenta toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Specifically, examples of the colorant contained in the cyan toner include C.I. I. Pigment blue 15: 3.

  The content of the colorant contained in the cyan toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Examples of the colorant contained in the black toner include carbon black, magnetic material, and titanium black. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Examples of magnetic materials include ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these ferromagnetic metals, compounds of ferromagnetic metals such as ferrite and magnetite, and ferromagnetic materials that do not contain ferromagnetic metals but are heat treated. The alloy shown etc. are mentioned. Examples of alloys that exhibit ferromagnetism by heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

  The content of the colorant contained in the black toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  The toner of the present invention can contain an internal additive such as a charge control agent and a release agent and other external additives as necessary.

<Binder resin>
As the binder resin contained in the toner base particles according to the present invention, for example, when the toner base particles are produced by a pulverization method, a dissolution suspension method, an emulsion aggregation method, or the like, a styrenic resin or (meth) acrylic resin is used. Resin, styrene- (meth) acrylic copolymer resin, vinyl resin such as olefin resin, polyester resin, polyamide resin, carbonate resin, polyether, polyvinyl acetate resin, polysulfone, epoxy resin, polyurethane Various known resins such as resins and urea resins can be used. These can be used alone or in combination of two or more.

(Crystalline resin)
The binder resin constituting the toner base particles preferably contains a crystalline resin from the viewpoint of facilitating melting of the toner particles and achieving energy saving at the time of fixing onto the recording medium. The crystalline resin is a resin having crystallinity. Examples thereof include crystalline polyester resins and crystalline vinyl resins. Among them, a crystalline polyester resin is preferable, and an aliphatic crystalline polyester resin is more preferable.
The crystalline polyester resin can be produced by a general polyester polymerization method in which the acid component and the alcohol component are reacted. Examples of the polymerization method include direct polycondensation and transesterification, and the polymerization method is appropriately used depending on, for example, the type of monomer.
The crystalline polyester resin can be produced, for example, at a polymerization temperature of 180 to 230 ° C. If necessary, the inside of the reaction system is depressurized and the monomer is reacted while removing water and alcohol generated by condensation. When the monomer is not dissolved or compatible with the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. If there is a monomer with poor compatibility in the copolymerization reaction, for example, if the monomer having poor compatibility is previously condensed with the acid or alcohol to be polycondensed with the monomer and then polycondensed together with the main component Good.

In addition, other binder resins may be included, and examples thereof include styrene- (meth) acrylic resins and polyester resins, partially modified polyester resins, and the like.
The styrene- (meth) acrylic resin has a molecular structure of a radical polymer of a compound having a radical polymerizable unsaturated bond, and can be synthesized, for example, by radical polymerization of the compound. One or more of the above compounds may be used, and examples thereof include styrene and derivatives thereof and (meth) acrylic acid and derivatives thereof.
Examples of the styrene and its derivatives include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn. -Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4- Dimethylstyrene and 3,4-dichlorostyrene are included.
Examples of the above (meth) acrylic acid and derivatives thereof include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid. Examples include butyl acid, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.
The polyester has a molecular structure of a condensation polymerization product of a polycarboxylic acid and a polyhydric alcohol, and can be synthesized by, for example, condensation polymerization of these.
The polyvalent carboxylic acid may be one kind or more. Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, dicarboxylic acids having a double bond, trivalent or higher carboxylic acids, anhydrides thereof, and lower alkyl esters thereof. Since the dicarboxylic acid having a double bond is radically cross-linked through a double bond, it is preferable from the viewpoint of preventing hot offset during fixing in toner particles.
Examples of the aliphatic dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, adipic acid, peric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12 -Dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid and 1,18-octadecanedicarboxylic acid are included.
Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid and mesaconic acid.
Examples of the dicarboxylic acid having a double bond include maleic acid, fumaric acid, 3-hexenedioic acid and 3-octenedioic acid. Among these, fumaric acid or maleic acid is preferable from the viewpoint of cost.
Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid.
The polyhydric alcohol may be one kind or more. Examples of the polyhydric alcohol include aliphatic diols and trihydric or higher alcohols. Among these, an aliphatic diol is preferable from the viewpoint of obtaining a crystalline polyester resin described later, and a linear aliphatic diol having a main chain portion having 7 to 20 carbon atoms is more preferable.
When the aliphatic diol is the linear aliphatic diol, the crystallinity of the polyester is maintained, and a decrease in the melting temperature of the polyester is suppressed. Therefore, it is preferable from the viewpoint of obtaining the two-component developer having excellent toner blocking resistance, image storage stability and low-temperature fixability. In addition, when the main chain portion of the linear aliphatic diol has 7 to 20 carbon atoms, the melting point of the product when polycondensation with the aromatic dicarboxylic acid is suppressed, and low-temperature fixing is realized. It is preferable from the viewpoint. Moreover, it is easy to obtain materials practically. From these viewpoints, the main chain portion preferably has 7 to 14 carbon atoms.
Examples of the aliphatic diol suitably used for the synthesis of the crystalline polyester resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol 1,14-tetradecanediol, 1,18-octadecanediol and 1,14-eicosandecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, or 1,10-decanediol is preferable from the viewpoint of availability.
Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.
You may add the chain transfer agent for adjusting the molecular weight of resin obtained to the monomer component at the time of synthesize | combining the said binder resin. One or more chain transfer agents may be used, and the chain transfer agent is used in an amount capable of achieving the above object within the range where the effects of the present embodiment are exhibited. Examples of such chain transfer agents include mercaptans such as 2-chloroethanol, octyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, and styrene dimers.

[Silica particles A and silica particles B]
The toner for developing an electrostatic latent image of the present invention contains two types of silica particles, silica particles A and silica particles B, as external additives.
In the present invention, the toner preferably contains 0.1 to 1.5% by mass of silica particles A and 0.1 to 1.5% by mass of silica particles B from the viewpoint of effect expression.

<Silica particle A>
Silica particles A have a number average primary particle diameter in the range of 10 to 50 nm and are hydrophobized with an alkylalkoxysilane having a structure represented by the following general formula (1).
When the number average primary particle diameter is smaller than 10 nm, it is impossible to suppress the external additive from being scraped. When the number average primary particle diameter is larger than 50 nm, the charge rising in a high temperature and high humidity environment is deteriorated. . It is preferable that the number average primary particle size is in the range of 15 to 40 nm because the external additive can be more easily scraped and the charge rising in a high temperature and high humidity environment can be more suitably performed.

<Alkylalkoxysilane>
The alkyl alkoxysilane according to the present invention is a compound having a structure represented by the following general formula (1).
Formula (1) R ¹ —Si (OR ² ) ₃
R ¹ : a linear alkyl group having 12 to 16 carbon atoms which may have a substituent R ² : a methyl group or an ethyl group

Examples of alkyl alkoxysilane having the structure represented by the general formula (1), _{specifically, C H 3 - (CH 2} ) 11 -Si (OCH 3) 3, CH 3 - (CH 2) 11 _{-Si (OC 2 H 5) 3} , CH 3 - (CH 2) 13 -Si (OCH 3) 3, CH 3 - (CH 2) 13 -Si (OC 2 H 5) 3, CH 3 - (CH 2 ) ₁₅ -Si (OCH ₃ ) ₃ , CH _3- (CH ₂ ) ₁₅ -Si (OC ₂ H ₅ ) _{3, and the} like, which may be alkylalkoxysilanes having a structure represented by the general formula (1) However, the present invention is not limited to this.

As described above, R ¹ is a linear alkyl group having 12 to 16 carbon atoms, and more preferably a linear alkyl group having 12 to 14 carbon atoms.
When the number of carbon atoms in R ¹ is lower than 12 , the degree of hydrophobicity is lowered, and a sufficient charge amount is not exhibited in a high temperature and high humidity environment. In addition, since the adhesiveness is lowered, it becomes difficult to form a damming layer in the cleaning portion.
Further, when the number of carbon atoms in R ¹ is larger than 16, the cohesiveness of the external additive itself containing the silica particles A becomes too high, and it is difficult to disintegrate and adhere the silica particles A to the toner base surface. Become.
R ¹ may have a substituent as long as the effect of the present invention is not inhibited, but is preferably a straight chain.

R ² is a methyl group or an ethyl group as described above, and a methyl group is more preferable from the viewpoint of reactivity.
When the functional group of R ² is three-dimensionally large, it becomes difficult to treat (modify) the surface of the silica particles. In addition, when R ² is hydrogen, since the general formula (1) is a compound having a hydroxy group, the chemical affinity with water is increased. As a result, the charge amount leakage point in a high temperature and high humidity environment This is not preferable.

(Hydrophobic treatment of silica particles A)
The treatment for modifying the surface of the silica particles A with alkylalkoxysilane (hereinafter also referred to as “hydrophobization treatment of silica particles A”) can be performed by a well-known method that is usually performed, for example, a dry method or a wet method. The method can be used.

  The dry method is performed by stirring or mixing silica powder and an alkylalkoxysilane having a structure represented by the general formula (1) in a fluidized bed reactor.

In the wet method, silica powder is dispersed in a solvent to form a slurry of silica particles, and then an alkylalkoxysilane having a structure represented by the above general formula (1) is added to the slurry to obtain a surface of silica particles. Is modified (hydrophobized) with alkylalkoxysilane.
Further, the silica particles A can be hydrophobized using a batch method or a continuous method in which the dry silica powder is brought into contact with a liquid or vapor alkylalkoxysilane while thoroughly mixing.

The mixture of silica particles and alkylalkoxysilane can be effectively modified with alkylalkoxysilane on the silica particle surface by heating for 0.5 to 5 hours in the range of 100 to 200 ° C. .
In addition, as a quantity of the said alkyl alkoxysilane which is a surface treatment (surface modification) agent, the range of 5-30 mass parts is preferable with respect to 100 mass parts of silica particles, and the range of 8-20 mass parts is more preferable.

<Silica particle B>
Silica particles B have a number average primary particle diameter in the range of 10 to 50 nm and are hydrophobized with silazane.
When the number average primary particle diameter is smaller than 10 nm, it is impossible to suppress the external additive from being scraped. When the number average primary particle diameter is larger than 50 nm, the charge rising in a high temperature and high humidity environment is deteriorated. . A number average primary particle size of 15 to 40 nm is preferable because the external additive can be more easily scraped off and charging can be performed in a high-temperature and high-humidity environment.

(Silazane)
In the present invention, a known silazane can be used as long as the effects of the present invention are not impaired, but hexamethyldisilazane or hexaethyldisilazane is preferable, and hexamethyldisilazane is more preferable.
If the silazane is hexamethyldisilazane or hexaethyldisilazane, the chain length of the functional group bonded to silicon does not become too long, thereby avoiding excessive adhesion (cohesiveness). As a result, since the toner fluidity can be prevented from being lowered, the cleaning property is further improved.

(Hydrophobic treatment of silica particles B)
The treatment for modifying the surface of the silica particles B with silazane (hydrophobization treatment) can be performed by a well-known method that is usually performed.
For example, hexamethyldisilazane is sprayed onto the silica powder, the reaction mixture is stirred at 50 to 250 ° C. for 0.5 to 3 hours, and further at 140 to 250 ° C. for about 0.5 to 3 hours, a nitrogen stream. Stir under and dry. By cooling this, silica particles B subjected to hydrophobic treatment can be obtained.
In addition, as the quantity of the said hexamethyldisilazane which is a surface treatment (surface modification) agent, the inside of the range of 5-30 mass parts is preferable with respect to 100 mass parts of silica particles B like silica particle A, and 8-20 masses. More preferably within the range of parts.

[Number average primary particle size]
As a method for measuring the number average primary particle size, a 30,000 times photograph of the toner is taken with a scanning electron microscope, and this photograph image is captured by a scanner. The image processing analyzer LUZEX AP (manufactured by Nireco) binarizes the external additive present on the toner surface of the photographic image, and calculates the horizontal ferret diameter for 100 external additives. The average value is the number average particle size.
Hereinafter, the number average primary particle diameter is also simply referred to as “particle diameter”.

[Internal additives / other external additives]
The toner of the present invention can contain an internal additive such as a charge control agent and a release agent and other external additives as necessary.

<Charge control agent>
The charge control agent is not particularly limited as long as it can give positive or negative charge by frictional charging, and various known positive charge control agents and negative charge control agents can be used.

  The content of the charge control agent is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

<Release agent>
Various known waxes can be used as the release agent.

  Examples of the wax include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long chain hydrocarbon waxes such as paraffin wax and sazol wax, and dialkyls such as distearyl ketone. Ketone wax, carnauba wax, montan wax, behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanedioldi Ester waxes such as stearate, tristearyl trimellitic acid, distearyl maleate, ethylenediamine behenylamide, tristearyl trimellitic acid Such as amide-based waxes such as bromide and the like.

  It is preferable that content of a mold release agent is 0.1-30 mass parts with respect to 100 mass parts of binder resin, More preferably, it is 1-10 mass parts.

<Large diameter silica>
In the present invention, in addition to silica particles A and silica particles B, the number average primary particle size is in the range of 70 to 250 nm and the average circularity is in the range of 0.850 to 0.950. It is preferable that particles (hereinafter also referred to as “large-diameter silica”) are further contained as an external additive.
When the particle diameter of the large silica is 70 nm or more (that is, when the particle diameter is close to that of silica particles A and B), the silica particles A and silica particles B having a particle diameter of 10 to 50 nm It is possible to avoid mixing in the anti-sudging layer formed at the tip, whereby a dense layer can be formed.
Further, when the particle diameter of the large silica is 250 nm or less, the spacer function is prevented from becoming too high, and as a result, it is possible to avoid the frictional charging between the toner and the carrier.
Further, the large-diameter silica preferably has an average circularity in the range of 0.850 to 0.950 as described above. When the average circularity of the large-diameter silica is 0.850 or more, the toner fluidity is not significantly lowered, and it is possible to avoid the frictional charging between the toner and the carrier. If the average circularity of the large-diameter silica is 0.950 or less, it is possible to suppress the occurrence of abrasion at the tip of the cleaning unit.

  As a method for producing large-diameter silica, there are a method of obtaining a silica sol using water glass as a raw material, and a method of producing a particle by a sol-gel method using a silicon compound typified by alkoxysilane as a raw material. In particular, the production by the sol-gel method is preferable from the viewpoint of controlling the shape of the silica particles. In the method for producing silica particles by the sol-gel method, tetraalkoxysilane is reacted with tetraalkoxysilane as a raw material in the presence of an alcohol containing an alkali catalyst while supplying a tetraalkoxysilane as a raw material and an alkali catalyst as a catalyst. A method for producing particles. In addition to catalysis, the alkali catalyst coordinates to the surface of the generated core particle and contributes to the shape and dispersion stability of the core particle. However, since the alkali catalyst does not uniformly cover the surface of the core particle, Although the dispersion stability of the particles is maintained, a partial deviation occurs in the surface tension and chemical affinity of the core particles, so that core particles with low circularity can be generated.

<Other external additives>
From the viewpoint of controlling the fluidity and chargeability of the toner particles, it is preferable to further include an external additive in addition to the silica particles A, the silica particles B, and the large-diameter silica. Examples of the external additive include titania particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles and Boron oxide particles are included.
The number average primary particle size of the external additive can be adjusted, for example, by classification or mixing of classified products.
The surface of the external additive is preferably hydrophobized. A known surface modifier is used for the hydrophobic treatment. Examples of the surface modifier include silane coupling agents, titanate coupling agents, aluminate coupling agents, fatty acids, fatty acid metal salts, esterified products thereof, rosin acid, silicon oil, and the like.

(Average circularity)
The silica particles after being externally added to the toner particles are observed with an SEM apparatus, and are obtained as “100 / SF2” calculated by the following formula (1) from the planar image analysis of the obtained silica particles.
Circularity (100 / SF2) = 4π × (A / I ² ) Formula (1)
In formula (1), I represents the perimeter of the silica particles on the image, and A represents the projected area of the silica particles. SF2 represents a shape factor. The average circularity of the silica particles is obtained as 50% circularity in the cumulative frequency of 100 circularity of the silica particles obtained by the planar image analysis.

≪Toner production method≫
The method for producing the toner according to the present invention is not particularly limited, and a known method can be adopted, but an emulsion polymerization aggregation method or an emulsion aggregation method can be preferably employed.

  The emulsion polymerization aggregation method preferably used in the method for producing a toner according to the present invention is a dispersion of fine particles of a binder resin produced by an emulsion polymerization method (hereinafter also referred to as “binder resin fine particles”) as a colorant. The fine particles (hereinafter also referred to as “colorant fine particles”) are mixed with a dispersion liquid of a release agent such as a dispersion liquid and wax, and the toner particles are aggregated until a desired particle diameter is obtained. In this method, toner particles are manufactured by controlling the shape by fusing.

Further, the emulsion aggregation method preferably used as a method for producing the toner according to the present invention is a method in which a binder resin solution dissolved in a solvent is dropped into a poor solvent to obtain a resin particle dispersion, and the resin particle dispersion and the colorant dispersion And a release agent dispersion such as wax, and agglomerate until a desired toner particle diameter is obtained. Further, the shape is controlled by fusing the binder resin fine particles to produce toner particles. Is the method.
Either method can be applied to the toner of the present invention.

An example of using the emulsion polymerization aggregation method as a method for producing the toner of the present invention is shown below.
(1) Step of preparing a dispersion liquid in which fine particles of colorant are dispersed in an aqueous medium (2) Dispersion in which binder resin fine particles containing an internal additive are dispersed in an aqueous medium as required Step of preparing liquid (3) Step of preparing dispersion of binder resin fine particles by emulsion polymerization (4) Mixing dispersion of fine particles of colorant and dispersion of binder resin fine particles, Step of forming toner base particles by agglomerating, associating and fusing the fine particles of the resin and the binder resin fine particles (5) The toner base particles are filtered off from the dispersion system (aqueous medium) of the toner base particles to obtain a surfactant, etc. (6) Step of drying toner base particles (7) Step of adding external additive to toner base particles

  In the case of producing a toner by the emulsion polymerization aggregation method, the binder resin fine particles obtained by the emulsion polymerization method may have a multilayer structure of two or more layers made of binder resins having different compositions. For example, a binder resin fine particle having a two-layer structure is prepared by preparing a dispersion of resin particles by emulsion polymerization treatment (first-stage polymerization) according to a conventional method, and adding a polymerization initiator to the dispersion. It can be obtained by adding a polymerizable monomer and polymerizing this system (second stage polymerization).

  In addition, toner particles having a core / shell structure can be obtained by an emulsion polymerization aggregation method. Specifically, the toner particles having a core / shell structure are firstly binder resin fine particles for core particles and fine particles of colorant. The core particles are prepared by agglomerating, associating and fusing, and then the binder resin fine particles for the shell layer are added to the core particle dispersion to agglomerate the binder resin fine particles for the shell layer on the core particle surface. , And can be obtained by forming a shell layer that covers the surface of the core particles by fusing.

An example of using a pulverization method as a method for producing the toner of the present invention is shown below.
(1) A step of mixing a binder resin, a colorant and, if necessary, an internal additive by a Henschel mixer or the like (2) a step of kneading the obtained mixture while heating with an extrusion kneader or the like (3) obtained Step of coarsely pulverizing the kneaded product with a hammer mill or the like, and further pulverizing with a turbo mill pulverizer or the like (4) The obtained pulverized product is finely classified using, for example, an airflow classifier utilizing the Coanda effect. Step of forming toner base particles (5) Step of adding external additive to toner base particles

[Particle size of toner particles]
The particle diameter of the toner particles constituting the toner of the present invention is preferably 4 to 10 μm, and more preferably 5 to 9 μm, for example, in terms of volume-based median diameter.

  When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of the toner particles is measured and calculated using a measuring apparatus in which a data processing computer system (Beckman Coulter, Inc.) is connected to “Multisizer 3” (Beckman Coulter, Inc.).

  Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Then, ultrasonic dispersion treatment was performed for 1 minute to prepare a toner particle dispersion, and this toner particle dispersion was placed in “ISOTON II” (Beckman Coulter, Inc.) in the sample stand. Pipette into beaker until display concentration of measuring device is 5-10%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Is the volume-based median diameter.

≪Overview of two-component developer for electrostatic latent image development≫
The toner for developing an electrostatic latent image of the present invention can be used as a non-magnetic one-component developer, but can be suitably used for a two-component developer for developing an electrostatic latent image containing a carrier.

[Career]
The carrier particles are made of a magnetic material. Examples of the carrier particles include coated carrier particles having core material particles made of the magnetic material and a coating material layer covering the surface, and resin dispersion in which fine powder of the magnetic material is dispersed in the resin. Type carrier particles. The carrier particles are preferably the coated carrier particles from the viewpoint of suppressing the adhesion of the carrier particles to the photoreceptor.

<Carrier core (core particle)>
The core particle is composed of a magnetic material, for example, a substance that is strongly magnetized in the direction by a magnetic field. The magnetic material may be one kind or more, and examples thereof include metals exhibiting ferromagnetism such as iron, nickel and cobalt, alloys or compounds containing these metals, and alloys exhibiting ferromagnetism by heat treatment, Is included.
Examples of the metal exhibiting ferromagnetism or a compound containing the same include iron, ferrite represented by the following formula (a), and magnetite represented by the following formula (b). M in the formulas (a) and (b) represents one or more monovalent or divalent metals selected from the group consisting of Mn, Fe, Ni, Co, Cu, Mg, Zn, Cd, and Li.
Formula (a): MO · Fe ₂ O ₃
Formula (b): MFe ₂ O ₄
Examples of alloys that exhibit ferromagnetism upon heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.
The core particles are preferably various ferrites. This is because the specific gravity of the coated carrier particles is smaller than the specific gravity of the metal constituting the core material particles, so that the impact force of stirring in the developing device can be further reduced.

<Carrier coat resin (coating material)>
The coating material may be one type or more. As the coating material, a known resin used for coating the core particles of the carrier particles can be used. It is preferable that the coating material is a resin having a cycloalkyl group from the viewpoint of reducing the moisture adsorptivity of the carrier particles and increasing the adhesion of the coating layer to the core material particles. Examples of the cycloalkyl group include a cyclohexyl group, a cyclopentyl group, a cyclopropyl group, a cyclobutyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group. Among these, a cyclohexyl group or a cyclopentyl group is preferable, and a cyclohexyl group is more preferable from the viewpoint of adhesion between the coating layer and the ferrite particles. The weight average molecular weight Mw of the resin is, for example, 10,000 to 800,000, and more preferably 100,000 to 750000. Content of the said cycloalkyl group in the said resin is 10-90 mass%, for example. The content of the cycloalkyl group in the resin can be determined by, for example, pyrolysis-gas chromatography / mass spectrometry (P-GC / MS), ¹ H-NMR, or the like.

[Two-component developer]
The two-component developer is obtained by appropriately mixing the toner particles and carrier particles so that the toner particle content (toner concentration) is 4.0 to 8.0% by mass. Can be configured.
Examples of the mixing device used for the mixing include a Nauter mixer, a W cone, and a V-type mixer.

≪Image formation method≫
The toner of the present invention can be suitably used in a general electrophotographic image forming method together with black toner, yellow toner, magenta toner and cyan toner.

  The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

<< Manufacture of Toner 1 >>
[(1) -1. Preparation of silica particles A1]
100 parts by mass of silica powder having a number average primary particle size of 30 nm is put into a reactor, and in a nitrogen atmosphere, 3.0 g of water is sprayed with stirring, and decyltrimethoxysilane (hydrophobizing agent) is added thereto. 10 parts by mass of CH _3- (CH ₂ ) ₉ -Si (OCH ₃ ) ₃ ) and 1.0 part by mass of diethylamine as a dispersing agent are sprayed, and heated with stirring at 180 ° C. for 1 hour, and then cooled to obtain silica particles A1. It was.

[(1) -2. Preparation of silica particle B1]
100 parts by mass of silica powder having a number average primary particle size of 30 nm is placed in a reactor, and 3.0 g of water is sprayed while stirring in a nitrogen atmosphere and stirring. Hexamethyldi, which is a hydrophobizing agent (silazane). 10 parts by mass of silazane (“HMDS” shown in Table 1) and 1.0 part by mass of diethylamine were sprayed, and the mixture was heated and stirred at 180 ° C. for 1 hour, and then cooled to obtain silica particles B1.

[(1) -3. Manufacturing method of large diameter silica]
(I) 630 parts by mass of methanol and 90 parts by mass of water were added to and mixed with a 3 liter reactor equipped with a stirrer, a dropping funnel and a thermometer. While stirring this solution, 950 parts by mass of tetramethoxysilane was hydrolyzed to obtain a suspension of silica particles. Subsequently, it heated at 60-70 degreeC, 390 mass parts of methanol was distilled off, and the aqueous suspension of the silica particle was obtained.
(Ii) To this aqueous suspension, 11.6 parts by mass of methyltrimethoxysilane (corresponding to 0.1 molar ratio with respect to tetramethoxysilane) was added dropwise at room temperature to hydrophobize the surface of the silica particles. .
(Iii) After adding 1400 parts by mass of methyl isobutyl ketone to the dispersion thus obtained, the mixture was heated to 80 ° C. to distill off methanol water. To the obtained dispersion, 280 parts by mass of hexamethyldisilazane was added at room temperature, heated to 120 ° C. and reacted for 3 hours to trimethylsilylate the silica particles. Thereafter, the solvent was distilled off under reduced pressure to prepare large-diameter silica.
When the number average primary particle diameter and true specific gravity of the large diameter silica obtained by the above method were measured, the number average primary particle diameter was 120 nm and the average circularity was 0.920.

[(2) Manufacturing method of toner base particles]
The method for producing toner base particles includes the following steps.
(2-1) Step of preparing a dispersion liquid in which colorant particles are dispersed in an aqueous medium (2-2) In the aqueous medium, the binder resin particles are formed by the binder resin to form the binder resin. A step of preparing a binder resin particle dispersion in which particles are dispersed;
(2-3) Resin particles that become toner base particles by mixing a dispersion of colorant particles and a dispersion of binder resin fine particles in an aqueous medium to aggregate the colorant particles and the binder resin. Process (coagulation / fusion process)
(2-4) Cooling step (2-5) Filtration, washing, drying step

<(2-1) Preparation of Colorant Fine Particle Dispersion>
While stirring a solution obtained by stirring and dissolving 11.5 parts by mass of sodium n-dodecyl sulfate in 160 parts by mass of ion-exchanged water, 24.5 parts by mass of copper phthalocyanine was gradually added to the solution. Next, by performing a dispersion treatment using a stirring device “Clearmix W Motion CLM-0.8” (manufactured by M Technique Co., Ltd.), the volume-based median diameter of the copper phthalocyanine particles in the solution is 126 nm. A colorant fine particle dispersion (A1) was prepared.

<(2-2) Step of preparing a binder resin particle dispersion in which binder resin particles are formed from a binder resin and the binder resin particles are dispersed in an aqueous medium>
(Preparation of crystalline polyester resin)
A mixed solution containing 300 g of 1,9-nonanediol, 250 g of dodecanedioic acid, and catalyst Ti (OBu) ₄ (0.014% by mass with respect to the carboxylic acid monomer) was prepared in a three-necked flask, The air in the container was decompressed by a decompression operation. Further, nitrogen gas was introduced into the three-necked flask to make the inside of the flask an inert atmosphere, and the mixture was refluxed at 180 ° C. for 6 hours while mechanically stirring. Thereafter, unreacted monomer components were removed by distillation under reduced pressure, and the temperature was gradually raised to 220 ° C., followed by stirring for 12 hours. The crystalline polyester resin (B1) was obtained by cooling when it became a viscous state. The obtained crystalline polyester resin (B1) had a weight average molecular weight (Mw) of 19,500. The crystalline polyester resin (B1) had a melting point of 75 ° C.

(Molecular weight measurement)
Using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent at a flow rate of 0.2 mL / The sample solution (crystalline polyester resin (B1) solution) 10 μL is injected into the apparatus and detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample is simply determined. It is determined by calculating using a calibration curve measured using dispersed polystyrene standard particles.

(Measuring melting point of crystalline resin)
The melting point of the crystalline resin was determined by using a differential scanning calorimeter “Diamond DSC” (manufactured by PerkinElmer), enclosing 3.0 mg of sample in an aluminum pan and setting it in a holder, and using an empty aluminum pan as a reference The first heating process for raising the temperature from 0 ° C. to 200 ° C. at a lifting speed of 10 ° C./min, the cooling process for cooling from 200 ° C. to 0 ° C. at the cooling speed of 10 ° C./min, and the lifting speed of 10 ° C./min Is measured under the measurement conditions (temperature increase / cooling conditions) in which the second temperature increase process in which the temperature is increased from 0 ° C. to 200 ° C. in this order. Based on the DSC curve obtained by this measurement, The endothermic peak top temperature derived from the crystalline polyester in the temperature process is taken as the melting point.

(Preparation of dispersion of resin particles (C1) (first stage polymerization))
4 g of polyoxyethylene (2) sodium dodecyl ether sulfate and 3000 g of ion-exchanged water were charged into a 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device, and the resulting mixture was run under a nitrogen stream at 230 rpm. The temperature of the mixture was raised to 80 ° C. while stirring at a stirring speed of. After the temperature rise, a solution prepared by dissolving 10 g of potassium persulfate in 200 g of ion-exchanged water is added to the above mixed solution, the liquid temperature of the mixed solution is set to 75 ° C., and the monomer mixed solution having the following composition is added over 1 hour. The mixture was dropped into the mixed liquid, and then the monomer was polymerized by heating and stirring the mixed liquid at 75 ° C. for 2 hours to prepare a dispersion of resin particles (C1).
Styrene 568g
164 g of n-butyl acrylate
Methacrylic acid 68g

(Preparation of dispersion of resin particles (C2) (second stage polymerization))
A solution obtained by dissolving 2 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 3000 g of ion-exchanged water was charged into a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device. Was heated to 80 ° C.
On the other hand, a solution in which a monomer having the following composition was dissolved at 80 ° C. was prepared.

Resin particles (C1) 42g (solid content conversion)
70g of wax
Crystalline polyester resin (B1) 70g
Styrene 195g
N-butyl acrylate 91g
Methacrylic acid 20g
n-Octyl mercaptan 3g

  Thereafter, the solution is added to the above mixed solution, and mixed and dispersed for 1 hour by a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path, thereby dispersing emulsified particles (oil droplets). A liquid was prepared. Next, an initiator solution in which 5 g of potassium persulfate is dissolved in 100 g of ion-exchanged water is prepared, added to the dispersion, and the obtained dispersion is heated and stirred at 80 ° C. for 1 hour to form the monomer. A dispersion of resin particles (C2) was prepared.

(Preparation of dispersion of core binder resin fine particles (C3) (third stage polymerization))
A solution prepared by dissolving 10 g of potassium persulfate in 200 g of ion-exchanged water was further added to the above dispersion of resin particles (C2), and the resulting dispersion was maintained at 80 ° C. The mixture was added dropwise to the dispersion over 1 hour.

298 g of styrene
137 g of n-butyl acrylate
50g of n-stearyl acrylate
Methacrylic acid 64g
n-Octyl mercaptan 6g

  After completion of the dropwise addition, the obtained dispersion is heated and stirred for 2 hours to polymerize the monomer, and then the dispersion is cooled to 28 ° C. to disperse the core binder resin fine particles (C3). A liquid was prepared.

(Preparation of dispersion of binder resin fine particles (D1) for shell)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device, a surfactant solution in which 2.0 g of sodium polyoxyethylene dodecyl ether sulfate was dissolved in 3000 g of ion-exchanged water was charged, and the reaction was performed at 230 rpm under a nitrogen stream. The temperature of the solution was raised to 80 ° C. while stirring at a stirring speed. To this solution, an initiator solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, and a monomer mixed solution having the following composition was dropped into the solution over 3 hours.
564 g of styrene
N-butyl acrylate 140g
Methacrylic acid 96g
12g of n-octyl mercaptan

  After the dropwise addition, the resulting mixture was heated and stirred at 80 ° C. for 1 hour to polymerize the monomer, thereby preparing a dispersion of binder resin fine particles for shell (D1).

(Preparation of core / shell particles (1-3 aggregation / fusion process))
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, 360 g of the binder resin particles for core (C3) (solid content conversion), 1100 g of ion-exchanged water, and colorant particles After adding 50 g of the dispersion (A1) and adjusting the temperature of the obtained dispersion to 30 ° C., a 5N sodium hydroxide aqueous solution was added to the dispersion to adjust the pH of the dispersion to 10. Next, an aqueous solution in which 60 g of magnesium chloride was dissolved in 60 g of ion-exchanged water was added to the dispersion at 30 ° C. with stirring for 10 minutes. After the addition, the dispersion is kept at 30 ° C. for 3 minutes and then the temperature rise is started. The dispersion is heated to 85 ° C. over 60 minutes, and the particle growth reaction is carried out while keeping the temperature of the dispersion at 85 ° C. To prepare a dispersion of pre-core particles (1). 80 g (solid content conversion) of the binder resin fine particles for shell (D1) was added thereto, and stirring was continued for 1 hour at 80 ° C., and the binder resin fine particles for shell (D1) were formed on the surface of the pre-core particles (1). ) Was fused to form a shell layer to obtain resin particles (1). Here, an aqueous solution in which 150 g of sodium chloride was dissolved in 600 g of ion-exchanged water was added to the obtained dispersion, and aged at a liquid temperature of 80 ° C., and the average circularity of the resin particles (1) was 0.960. When it became, it cooled to 30 degreeC (2-4 cooling process). The number-based median diameter of the core / shell particles (1) after cooling was 5.5 μm.

(Measurement of median diameter based on the number of toner base particles)
The number-based median diameter (D _nt ) of the toner base particles was measured and calculated using a device in which a computer system for data processing was connected to “Multisizer 3 (manufactured by Beckman Coulter)”.
As a measurement procedure, 0.02 g of toner base particles was added to 20 mL of a surfactant solution (for example, a surfactant solution in which a neutral detergent containing a surfactant component was diluted 10 times with pure water for the purpose of dispersing toner base particles. Then, ultrasonic dispersion was performed for 1 minute to prepare a toner base particle dispersion. This toner base particle dispersion is poured into a beaker containing ISOTON II (manufactured by Beckman Coulter, Inc.) in a sample stand with a pipette until the measured concentration becomes 5 to 10%, and the measuring machine count is set to 25,000. Measured. The aperture size of the multisizer 3 is 100 μm. The frequency number obtained by dividing the measurement range of 1 to 30 μm into 256 parts was calculated, and the particle diameter of 50% from the larger number integrated fraction was taken as the number reference median diameter (D _nt ).

(Measurement of average circularity of toner base particles)
The average circularity of the toner base particles is a value measured using a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex). Specifically, the toner base particles are moistened with an aqueous surfactant solution, and ultrasonic dispersion is performed for 1 minute. After dispersion, the HPF is used in the measurement condition HPF (high magnification imaging) mode using “FPIA-3000”. Measurement was performed at an appropriate concentration of 3000 to 10,000 detections. Within this range, reproducible measurement values can be obtained. The circularity was calculated by the following formula.
Formula: Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)
The average circularity is an arithmetic average value obtained by adding the circularity of each particle and dividing by the total number of particles measured.

<Preparation of toner base particles (2-5 filtration, washing, drying step)>
The dispersion of the core / shell particles (1) produced in the aggregation / fusion process was subjected to solid-liquid separation with a centrifuge to form a wet cake of the core / shell particles. The wet cake is washed with ion-exchanged water at 35 ° C. until the electric conductivity of the filtrate reaches 5 μS / cm with the centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). Was dried to 0.8% by mass to prepare toner base particles 1.

(Production of toner particles 1 (external additive treatment step))
The following external additives are added to the toner base particles 1 and added to the Henschel mixer model “FM20C / I” (manufactured by Nippon Coke Industries, Ltd.), and the blade tip peripheral speed is 40 m / s. The number of rotations was set and the mixture was stirred for 15 minutes to produce toner particles 1.
Large-diameter silica 1.0 part by mass Silica particle A1 1.0 part by mass Silica particle B1 1.0 part by mass Hydrophobic titanium oxide 0.5 part by mass

  The temperature during mixing of the external additive to the toner particles 1 was set to 40 ° C. ± 1 ° C. When the temperature reaches 41 ° C., the cooling water is supplied to the outer bath of the Henschel mixer at a flow rate of 5 L / min. When the temperature reaches 39 ° C., the flow rate of the cooling water is 1 L / min. In this way, the temperature inside the Henschel mixer was controlled by flowing cooling water.

<Average circularity of large diameter silica>
The large-diameter silica after being externally added to the toner particles was observed with a SEM apparatus, and was obtained as “100 / SF2” calculated by the following formula (1) from the planar image analysis of the obtained silica particles.
Circularity (100 / SF2) = 4π × (A / I ² ) Formula (1)
In formula (1), I represents the perimeter of the silica particles on the image, and A represents the projected area of the silica particles. SF2 represents a shape factor. The average circularity of the large diameter silica was obtained as 50% circularity in the cumulative frequency of the 100 circular diameters of the large diameter silica obtained by the planar image analysis.

[Production of Toners 2-28]
In the production method of the toner 1, instead of the silica particles A1, the silica particles A2 to A11 having alkyl alkoxysilanes having the particle diameters shown in Table 1 and the structure represented by the general formula (1) are used, and instead of the silica particles B1. The silica particles B2 to B7 having the particle sizes and silazanes described in Table 1 were used. Further, the large-diameter silica in the production method of the toner 1 was changed to a large-diameter silica having the particle diameter shown in Table 1. Other than that, Toners 1 to 28 were produced in the same manner as in Toner 1 production method.

≪Evaluation method≫
In order to evaluate each of the toners 1 to 28, two-component developers 1 to 28 were prepared as follows, and the following cleaning properties and charging performances were evaluated.

[Developer production method]
(Preparation of two-component developer 1)
The toner particles 1 and the carrier particles 1 produced as described below are mixed for 30 minutes in a V-type mixer so that the content (toner concentration) of the toner particles 1 in the two-component developer is 7% by mass. Thus, a two-component developer 1 was produced.

<Method for producing carrier particle 1>
(Preparation of core coating resin (coating material 1))
In an aqueous solution of 0.3% by weight sodium benzenesulfonate, cyclohexyl methacrylate and methyl methacrylate were added at a molar ratio of 1: 1, and an amount of potassium persulfate corresponding to 0.5% by weight of the total amount of monomers was added. The coating material 1 which is resin for core material coating was produced by adding and performing emulsion polymerization and drying the resin particle in the obtained dispersion liquid by the spray drying of the said dispersion liquid. The obtained coating material 1 had a weight average molecular weight Mw of 500,000. The Mw of the covering material 1 was determined by gel permeation chromatography (GPC) in the same manner as the crystalline polyester resin (B1) described above.

(Preparation of carrier particles)
Mn—Mg ferrite particles having a volume average diameter of 30 μm were prepared as core particles. In a high-speed stirring mixer with a horizontal stirring blade, 100 parts by mass of the ferrite particles and 4.5 parts by mass of the coating material 1 are charged, and the peripheral speed of the horizontal rotary blade is 8 m / sec. And stirred for 15 minutes. Thereafter, the mixture was mixed at 120 ° C. for 50 minutes, and the coating material 1 was coated on the surface of the core material particles by the action of mechanical impact force (mechanochemical method) to produce carrier particles 1. The volume-based median diameter of the carrier particles 1 was 32 μm.

(Measurement of volume-based median diameter of carrier particles)
The volume-based median diameter (D _vc ) of the carrier particles is measured by a wet method using a laser diffraction particle size distribution measuring device “HELOS KA” (manufactured by Nippon Laser Corporation). Specifically, first, an optical system with a focal position of 200 mm is selected, and the measurement time is set to 5 seconds. Then, the magnetic particles for measurement are added to a 0.2% sodium dodecyl sulfate aqueous solution and dispersed for 3 minutes using an ultrasonic cleaner “US-1” (manufactured by Asone) to prepare a sample dispersion for measurement. Then, several drops are supplied to “HELOS KA”, and the measurement is started when the sample concentration gauge reaches the measurable region. With respect to the obtained particle size distribution, a cumulative distribution was created from the smaller diameter side with respect to the particle size range (channel), and the particle size at 50% cumulative was taken as the volume-based median diameter.

<Preparation of two-component developer 2 to 28>
Two-component developers 2 to 28 were prepared in the same manner as in the preparation of the two-component developer 1 except that the toner particles 2 to 28 were used instead of the toner particles 1.

[Evaluation]
As an evaluation apparatus, a commercially available digital full-color multifunction peripheral “bizhub PRO C6500” (manufactured by Konica Minolta, “bizhub” is a registered trademark of the company) was used. Each of the two-component developers 1 to 28 was loaded, and evaluation of the toners 1 to 28 was performed as follows in a high temperature and high humidity (30 ° C., 80% RH) environment. The results are as shown in Table 2.

<Cleanability>
100,000 test images with 5 solid strips of 3 cm width on A4 high-quality paper (65 g / m ² ) were printed continuously (endurance printing), and the entire surface after endurance was output. The density of 5 points corresponding to the band part and 6 points corresponding to the non-band part was measured, and the evaluation was performed with the maximum density difference, and the determination was made according to the following criteria. It was judged that 0.10 or less was practical.

◎: Maximum density difference is 0.05 or less ○: Maximum density difference is larger than 0.05 and 0.10 or less △: Maximum density difference is larger than 0.10 and 0.15 or less ×: Maximum density difference is from 0.15 large

<Charging performance>
The initial charge amount and the post-durability charge amount were measured. Specifically, the initial charge amount was taken from the developer on the mag roll after printing 10 sheets, and the post-endurance charge amount was taken from the developer on the mag roll after printing 100,000 sheets to measure the charge amount. . The difference between the initial charge amount and the post-endurance charge amount is 10 μC / g or less (practical “◯” in Table 2). × ”), and the charging performance was evaluated when images with a high printing rate were continuously printed under severe use environment such as high temperature and high humidity.

Claims (4)

An electrostatic latent image developing toner containing toner particles comprising toner base particles containing at least a colorant and an external additive attached to the surface of the toner base particles,
As the external additive, at least,
Silica particles A having a number average primary particle diameter in the range of 10 to 50 nm and hydrophobized with alkylalkoxysilane having a structure represented by the following general formula (1):
An electrostatic latent image developing toner comprising two types of silica particles, silica particles B having a number average primary particle diameter in the range of 10 to 50 nm and hydrophobized with silazane.
Formula (1) R ¹ —Si (OR ² ) ₃
R ¹ : a linear alkyl group having 12 to 16 carbon atoms which may have a substituent R ² : a methyl group or an ethyl group   2. The electrostatic latent image developing toner according to claim 1, wherein the silazane is hexamethyldisilazane or hexaethyldisilazane.   The number average primary particle diameter is in the range of 70 to 250 nm, and further contains silica particles having an average circularity in the range of 0.850 to 0.950. Item 3. The electrostatic latent image developing toner according to Item 2. The toner base particles contain at least a binder resin, and
The electrostatic latent image developing toner according to claim 1, wherein the binder resin contains at least a crystalline resin.