JP2007304494A - Toner for electrostatic latent image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for electrostatic latent image development which retains its high powder fluidity and charging property, improves transfer stability with time and environmental stability of charge, and can stably obtain high-quality images. <P>SOLUTION: The toner for electrostatic latent image development comprises toner base particles containing a binder resin and a colorant and external additive particles, wherein the external additive particles are three kinds of external additive particles A, B and C different in particle diameter, and the average primary particle diameters R<SB>A</SB>, R<SB>B</SB>and R<SB>C</SB>of the external additive particles A, B and C and the methanol hydrophobicities (%) W<SB>A</SB>, W<SB>B</SB>and W<SB>C</SB>of the external additive particles A, B and C satisfy the relationships of the formula (1): R<SB>A</SB>>R<SB>B</SB>>R<SB>C</SB>and the formula (2): W<SB>A</SB><W<SB>B</SB><W<SB>C</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic latent image developing toner used for developing an electrostatic latent image in electrophotography, electrostatic recording method and the like.

  In electrophotography, an electrostatic latent image formed on the surface of a latent image carrier (photoconductor) is developed with a toner containing a colorant, and the obtained toner image is transferred to the surface of a recording material, which is then heated. An image can be obtained by fixing with a roll or the like. On the other hand, the latent image carrier is cleaned again to form an electrostatic latent image.

  The dry developer used in such electrophotography is a one-component developer using a toner in which a colorant or the like is blended in a binder resin, and a two-component developer in which a carrier is mixed with the toner. Broadly divided. Furthermore, the one-component developer is conveyed by a developer carrier by magnetic force using magnetic powder, and is conveyed by the developer carrier by a developing roll or the like without using magnetic powder and the magnetic one-component developer to be developed, It can be classified as a non-magnetic one-component developer to be developed.

In recent years, color machines have also become widespread, and in particular, two-component developers are used for these medium-speed and high-speed machines. In particular, with regard to full color image quality, high image quality close to high-quality printing and silver salt photography is desired.
Digitization processing is indispensable as means for achieving high image quality, and the effect of digitization related to such image quality is that complex image processing can be performed at high speed. This makes it possible to control characters and photographic images separately, and the reproducibility of both qualities is greatly improved compared to analog technology. In particular, for photographic images, gradation correction and color correction are possible, and this is advantageous over analog in terms of gradation characteristics, definition, sharpness, color reproduction, and graininess. However, on the other hand, it is necessary to faithfully form a latent image produced by an optical system as an image output, and as a toner, an activity aimed at faithful reproduction has been accelerated as the particle diameter is increasingly reduced. However, it is difficult to obtain a stable high image quality simply by reducing the particle size of the toner, and improvement of basic characteristics in development, transfer, and fixing characteristics is more important.

  Conventionally, fine particles have been externally added to the toner surface for the purposes of charge control, powder characteristics improvement, and transferability impartment, which are basic characteristics of the toner. In particular, the addition of inorganic fine particles is an effective means that has been used to improve toner fluidity, increase the charge level, and improve transfer characteristics.

  However, simply using these techniques makes these characteristics contradict each other, making it impossible to obtain a toner having excellent characteristics. In particular, when large-sized external additive particles are used, the fluidity of the toner deteriorates, and the large-sized external additive particles have low adhesion strength to the toner, so that they move to the recesses on the toner surface and are removed from the toner surface. There was a problem that separation occurred and transfer maintenance could not be sufficiently exhibited.

  In order to solve the above problem, a technique is known in which two kinds of small-diameter external additive particles that improve fluidity and large-diameter external additive particles that improve transfer maintainability are mixed to achieve both fluidity and transfer maintainability. (For example, refer to Patent Document 1). However, with this technique, even if the initial charging characteristics and the transfer characteristics can be compatible, the stability of charging and powder flowability over time cannot be achieved.

  On the other hand, there is a technique that uses three types of external additive particles having different particle diameters and effectively utilizes the characteristics of each particle diameter (see, for example, Patent Document 2). In this case, the small particle size particle is responsible for improving the fluidity, the medium particle size particle is responsible for preventing the small particle size from being buried, the fluidity is stabilized after the small particle size particle is buried, and the large particle size particle is responsible for the abrasiveness. However, the large-diameter particles have poor fluidity, charging characteristics, and transfer characteristics. Therefore, even if the fluidity of the small and medium-sized particles is improved, if the characteristics of the large-sized particles are not improved, the charging characteristics and fluidity are improved. Cannot be secured.

  Further, for the purpose of suppressing toner pulverization prevention and embedding prevention of external additives, three types of external additive particles having different particle diameters and three types of hydrophobic additive-treated external additive particles having different BET specific surface areas are used. Has been proposed (see, for example, Patent Documents 3 and 4). However, these techniques are intended for the stability of the toner shape, and are the same in that three types of external additive particles are used. There is no technical knowledge on the viewpoint of improving charging / powder flow characteristics and transfer maintenance. . Furthermore, it has been proposed to use three types of external additive particles having different charge amounts and different particle sizes (see, for example, Patent Document 5). To obtain such charging characteristics, large-diameter external additive particles are used. In addition, a bulky hydrophobizing agent having an untreated or amino group is used, which leads to poor fluidity and problems in powder characteristics.

  Also disclosed is a technique for defining the relationship between the specific surface area and the degree of hydrophobicity of the three external additive particles to improve the transfer maintenance property (see, for example, Patent Document 6). In this technique, the larger the specific surface area (the smaller the particle size), the smaller the degree of hydrophobicity of the external additive particles. However, if the degree of hydrophobicity of the external additive having a large specific surface area is reduced, the hygroscopicity is reduced. Becomes higher, resulting in a decrease in charge under high humidity. On the other hand, when these treatments are performed on the large-diameter external additive particles, the problem that the fluidity deteriorates cannot be avoided.

As described above, the addition of various external additive particles has been studied in order to improve the charge / flow characteristics and transferability of the toner, but these are still compatible, including the maintainability in the actual machine. The current situation is not established.
JP 57-17986 A JP 63-289559 A JP-A-6-258862 JP 2000-352837 A Japanese Patent Laid-Open No. 10-10773 JP 2000-321812 A

An object of the present invention is to solve the conventional problems and achieve the following objects.
In other words, the present invention maintains a high powder flowability and chargeability of the toner, improves the transfer stability with time and the environmental stability of the charge, and can stably obtain high-quality images. An object is to provide a latent image developing toner.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by optimizing the relationship between the particle size of external additive particles externally added to the toner surface and their characteristics, The present invention has been completed. That is, the present invention

<1> An electrostatic latent image developing toner having toner base particles and binder particles containing a binder resin and a colorant,
The external additive particles are three types of external additive particles A, B, and C having different particle diameters, and the average primary particle diameter of each external additive particle is R _A , R _B , and R _C. When the hydrophobization degree (%) of methanol is W _A , W _B , and W _C , these are toners for developing electrostatic latent images that satisfy the relationship of the following formulas (1) and (2).
_{R A> R B> R C} ··· Equation (1)
_{W A <W B <W C} ··· formula (2)

<2> When the three types of external additive particles A, B, and C are hydrophobized by different hydrophobizing agents, and the molecular weight of each hydrophobizing agent is X _A , X _B , and X _C These are the electrostatic latent image developing toners according to <1> that satisfy the relationship of the following formula (3).
_{X A <X B <X C} ··· (3)

<3> The three types of external additive particles A, B, and C are hydrophobized with a hydrophobizing agent, and the amount of hydrophobizing agent to be treated with respect to 100 parts by mass of the external additive core (part by mass). the M _a, M _B, when the M _C, they are electrostatic latent image developing toner according to <1> satisfy the relation of the following formula (4).
_{M A <M B <M C} ··· formula (4)

<4> molecular weight X _A hydrophobic treatment agent for use in the external additive particles A is an electrostatic latent image developing toner according to 50 or less <2>.

<5> The average primary particle diameter R _A of the external additive particles A is an electrostatic latent image developing toner according to at 60nm or more <1>.

  According to the present invention, the powder fluidity and chargeability of the toner are kept high, the transfer stability over time and the environmental stability of charging are improved, and a static image capable of stably obtaining a high-quality image. An electrostatic latent image developing toner can be provided.

Hereinafter, the present invention will be described in detail.
The electrostatic latent image developing toner of the present invention is a toner for developing an electrostatic latent image having toner base particles and external additive particles containing a binder resin and a colorant,
The external additive particles are three types of external additive particles A, B, and C having different particle diameters, and the average primary particle diameter of each external additive particle is R _A , R _B , and R _C. when methanol hydrophobizing degree of the _{(%) W a, W B} , and _{W C,} it is characterized by satisfying the relation of the following formula (1) and (2).
_{R A> R B> R C} ··· Equation (1)
_{W A <W B <W C} ··· formula (2)

  As described above, it is known that the use of three external additive particles having different particle diameters is effective in improving the form maintaining property and the transfer maintaining property. In this case, small particle size particles improve fluidity, medium particle size particles contribute to prevention of burying of small particle size particles, and large particle size particles contribute to abrasiveness. The particles need to be hydrophobized. However, as this hydrophobization treatment, it is necessary to increase the hydrophobicity to some extent by selecting the treatment amount and type of the hydrophobizing agent in order to prevent a decrease in charge amount under high humidity. There has been a problem that the fluidity drop due to the processing to large particle size becomes significant.

  The inventors of the present invention have made extensive studies on the above problems from the viewpoint of particularly reducing the influence of the hydrophobizing treatment on large-diameter particles. As a result, the hydrophobicity is changed for each external additive particle having a different particle size. Specifically, as shown in the above formulas (1) and (2), the smaller the particle size, the larger the degree of methanol hydrophobization, It has been found that the larger the particle size of the particles, the smaller the degree of hydrophobicity of methanol, so that the powder fluidity can be stabilized and the charge can be stabilized even with the use of the toner over time.

  That is, it can be seen that reducing the treatment amount of the hydrophobizing agent to the large-diameter external additive particles does not significantly affect the fluidity, while the treatment amount of the hydrophobizing agent to the small-diameter external additive particles, etc. It has been found that even if the amount is increased, the fluidity is not particularly affected and the hydrophobizing ability can be enhanced, so that the charging ability under high humidity can be secured. For medium-sized external additive particles, setting the amount of treatment in the middle is effective for continuing the functions of large-diameter and small-diameter external additive particles without affecting the chargeability and fluidity. I understood it.

The large, medium, and small external additive particles in the present invention are determined by the size relationship of the average primary particle diameters of the three external additive particles added to the toner base particles. The primary particle size is not defined.
The average primary particle size is measured for each powder by a laser diffraction / scattering type particle size distribution measuring device as will be described later. The particle size of each external additive particle thus measured is In actuality, the particle size coincides with the particle size dispersed on the surface of the toner base particles. These external additives having different particle diameters can be distinguished from observation with a field emission scanning electron microscope (FE-SEM). In addition, the surface treatment composition can be estimated from the amount of carbon by SEM-XMA (X-ray microanalyzer).

  As described above, by increasing the degree of hydrophobization of methanol as the particle size decreases, it is considered that the external additive of each particle size plays the following role. That is, for large-sized external additive particles, fluidity stabilization is ensured and the function of contributing to transfer maintenance is achieved. For small-sized external additive particles, hygroscopicity is prevented and charging fluctuation reduction under high humidity can be ensured. At the same time, the function of maintaining a high fluidity improvement effect from the beginning, and for the medium-sized external additive particles, while preventing the large-sized external additive particles from moving to and detaching from the concave portions of the toner base particle surface, The function of preventing the burying of the small-diameter external additive particles is secured. The combination of these three external additive particles was found to be the first to obtain a toner with high transfer efficiency that is resistant to stress fluctuations, with no change in fluidity with time and no change in charge with time under high humidity. It was.

  The electrostatic latent image developing toner of the present invention (hereinafter sometimes simply referred to as “toner”) has at least toner base particles containing a binder resin and a colorant and external additive particles, and is further necessary. Depending on the case, it has other components. These will be described later.

<Toner base particles>
First, toner base particles in the present invention will be described.
The toner base particles in the present invention contain a binder resin and a colorant, and contain other components as necessary.

(Binder resin)
As the binder resin in the present invention, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Examples of vinyl polymers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; It is possible.

  In particular, typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride. A copolymer, polyethylene, polypropylene, etc. are mentioned. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can also be mentioned. Among these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly preferable.

From the viewpoint of low-temperature fixability, a crystalline resin is also preferably used.
Specific examples of crystalline resins include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tridecanedioic acid and other long-chain alkyl dicarboxylic acids, butanediol, pentanediol, and hexanediol. , Polyester resins using long-chain alkyl and alkenyl diols such as heptanediol, octanediol, nonanediol, decanediol, batyl alcohol; amyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylic acid Heptyl, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate , (Meth) acrylic acid steari , Vinyl resins using long-chain alkyls such as oleyl (meth) acrylate and behenyl (meth) acrylate, and (meth) acrylic esters of alkenyl; and the like. From the viewpoint of adjusting the melting point within a preferable range, a polyester resin-based crystalline resin is preferable.

(Coloring agent)
The colorant for the toner base particles is not particularly limited and may be either a dye or a pigment, but a pigment is preferred from the viewpoint of light resistance and water resistance.

  Preferred pigments include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, Quinacridone, benzidine yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 can be used.

Magnetic powder can also be used as a colorant. As the magnetic powder, known magnetic materials such as ferromagnetic metals such as cobalt, iron and nickel, alloys and oxides of metals such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc and manganese can be used.
The above colorants can be used alone or in combination of two or more. The content of the colorant in the toner of the present invention is preferably 0.1 to 40 parts by mass, and more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the total toner raw material. In addition, by appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained.

(Other ingredients)
A release agent or a charge control agent may be added to the toner base particles as necessary. Generally as a mold release agent, it uses for the purpose of improving mold release property. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide Plant waxes such as carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Mineral / petroleum waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. In this invention, these mold release agents may be used individually by 1 type, and may use 2 or more types together.

  The content of the release agent is preferably 1 to 20 parts by mass, and more preferably 2 to 15 parts by mass with respect to 100 parts by mass of all raw materials of the toner base particles. If the amount is less than 1 part by mass, the effect of adding a release agent may not be obtained. If the amount exceeds 20 parts by mass, adverse effects on the chargeability tend to appear, and the toner is easily destroyed inside the developing machine, so that the mold release is performed. In addition to the effect that the agent or toner resin becomes spent on the carrier and the charge is likely to decrease, for example, when color toner is used, the surface of the image at the time of fixing becomes insufficient. This is not preferable because the release agent may easily stay in the image and the transparency may deteriorate.

  The melting point of the release agent is preferably 50 to 120 ° C, more preferably 60 to 100 ° C. When the melting point of the release agent is less than 60 ° C., the change temperature of the release agent may be too low, and the blocking resistance may be inferior, or the developability may deteriorate when the temperature in the copying machine increases. When the melting point exceeds 120 ° C., although there is an effect on hot offset, the toner may not be heated to the melting point of the release agent practically and may not substantially exhibit the action of the release agent. .

  The charge control agent is generally used for the purpose of improving the chargeability. Examples of the charge control agent include metal-containing azo compounds such as chromium azo dyes, iron azo dyes, and aluminum azo dyes; salicylic acid metal complexes, nigrosine and quaternary ammonium salts.

The toner base particles in the present invention are not particularly limited by the production method, and can be obtained by a known method. Specifically, for example, particles obtained by a kneading and pulverizing method of kneading, pulverizing, and classifying a binder resin and a colorant and, if necessary, a release agent and a charge control agent are mechanically mixed. A method of changing the shape by impact force or thermal energy, emulsion polymerization of a polymerizable monomer of a binder resin, a formed dispersion, a colorant, and a release agent and a charge control agent as necessary Emulsion polymerization agglomeration method to obtain toner base particles by mixing and agglomerating and heat-fusing the dispersion, a polymerizable monomer to obtain a binder resin, a colorant, if necessary, a release agent, charging Suspension polymerization in which a solution such as a control agent is suspended in an aqueous solvent for polymerization, a binder resin and a colorant, and if necessary, a solution such as a release agent and a charge control agent is suspended in an aqueous solvent. Examples thereof include a dissolution suspension method for granulation.
Further, a manufacturing method may be performed in which the toner base particles obtained by the above method are used as a core, and further, aggregated particles are attached and heat-fused to have a core-shell structure. From the viewpoint of the shape controllability of the toner base particles, it is preferably a wet production method of any one of an emulsion polymerization aggregation method, a suspension polymerization method and a dissolution suspension method.

  The toner base particles produced as described above preferably have a small particle size for the purpose of improving the image quality. However, if the diameter is too small, development is difficult with the conventional system from the viewpoint of charging and fluidity. That is, the volume average particle size is preferably in the range of 2 to 8 μm, and more preferably in the range of 4 to 7 μm.

  If the volume average particle size exceeds 8 μm, the image quality such as reproducibility of fine lines and halftone graininess deteriorates, and it is difficult to obtain good image quality when outputting photographic image quality. On the other hand, if it is less than 2 μm, the powder characteristics and the charging characteristics are extremely deteriorated, and it may be difficult to output at high speed by a conventional machine.

  A known method may be used as the particle size measurement method. A Coulter counter TA-II type (manufactured by Beckman-Coulter) is used as the measuring apparatus, and ISOTON-II (manufactured by Beckman-Coulter) is used as the electrolyte. As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This is added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. To obtain volume average distribution and number average distribution. The number of particles to be measured is preferably 50,000. The volume average particle size is obtained from the volume average distribution and the number average distribution thus obtained.

  When the crystalline resin described above is used, the melting point of the binder resin is preferably 50 to 180 ° C, and more preferably 60 to 150 ° C. When the melting point is lower than 50 ° C., toner storage stability and image storage stability after fixing may become a problem. On the other hand, when the temperature is higher than 180 ° C., the power consumption of the machine is increased, which may not be economical.

  In the case of a crystalline resin, a plurality of melting peaks may be shown. In the present invention, the maximum peak is regarded as the melting point. For measurement of the glass transition temperature (Tg) and melting point (Tm) of the toner base particles, DSC-7 (differential thermal analyzer) manufactured by Perkin Elmer can be used. The temperature correction of the detection part of the apparatus uses the melting points of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. As the sample, an aluminum pan was used, and an empty pan was set as a control, and measurement was performed at a heating rate of 10 ° C./min.

<External additive particles>
Next, the external additive particles used in the present invention will be described.
The toner base particles in the present invention become toner for developing an electrostatic latent image by dispersing three external additive particles A, B and C having different particle diameters on the surface thereof. In the present invention, the average primary particle diameters of the external additive particles A, B, and C are R _A , R _B , and R _C, and the degree of methanol hydrophobization (%) is W _A , W _B , and W _C , respectively. Sometimes, it is necessary that these satisfy the relationship of the following formulas (1) and (2).
_{R A> R B> R C} ··· Equation (1)
_{W A <W B <W C} ··· formula (2)

  The average primary particle diameter is measured using a laser diffraction / scattering particle size distribution measuring apparatus (Mastersizer 2000, manufactured by Malvern). In addition, the larger the value of the degree of methanol hydrophobicity W (%), the higher the hydrophobicity. Details of these measuring methods will be described later.

The average primary particle diameter R of each of the three external additive particles having different particle diameter in the present invention is not particularly limited as described above, R _A is a range of 60~300nm large diameter external additive particles, middle size _{R B} is the range of 20~80nm external additive particles, _{R C} of the small-diameter external additive particles is preferably in the range of 5 to 40 nm.
In particular, _RA is preferably 60 nm or more from the viewpoint of exerting an effect as a spacer for improving toner transferability.

  In the external additive particles A, B, and C having the above particle size relationship, the degree of methanol hydrophobization is represented by the formula (2). The decrease can be prevented, and the small-diameter external additive particles can ensure a reduction in electrification fluctuation under high humidity while maintaining high fluidity. Further, with respect to the medium-sized external additive particles, the detachment of the large-diameter external additive particles and the burying of the small-diameter external additive particles can be prevented without affecting the fluidity and chargeability by the hydrophobization treatment.

  When the degree of methanol hydrophobization of the large-sized external additive particles is intermediate or maximum among the three external additive particles, the fluidity is lowered. In addition, when the methanol hydrophobization degree of the medium-sized external additive particles is minimized, the moisture absorption amount is increased, and the charge is decreased due to stress over time under high humidity, and when the methanol hydrophobization degree is maximized, The liquidity in the market deteriorates. Further, when the methanol hydrophobization degree of the small-diameter external additive particles is minimum or intermediate, the moisture absorption amount becomes high, and the charge under high humidity decreases.

The methanol hydrophobizing degree W of the three external additive particles having different particle diameter in the present invention, W _A is 20 to 60% of the large-diameter external additive particles, W _B of the middle-diameter external additive particles 30 80% of range, _{W C} of the small-diameter external additive particles is preferably in the range of 40% to 90%.
In particular W _A 60% in terms of the powder flowability below are those that are preferable from the viewpoint of charging property is 20% or more.

  The external additive particles are not particularly limited, but inorganic fine particles are preferably used. Examples of the inorganic fine particles include all inorganic fine particles usually used as an external additive on the toner surface, such as silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, and cerium oxide.

In the present invention, it is preferable that the external additive particles are hydrophobized with a hydrophobizing agent so that the degree of methanol hydrophobization between the external additive particles satisfies the relationship of the above formula (2).
Although there is no restriction | limiting in particular as a hydrophobization processing agent, For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, silicone oil etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.

  As the silane coupling agent, for example, any one of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Here, the following can be illustrated as a hydrophobic treatment agent used for surface treatment.

  That is, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxy Silane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (trimethylsilyl) Urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy Lan, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Representative examples include propyltrimethoxysilane and γ-chloropropyltrimethoxysilane.

In the present invention, regarding the external additive particles A, B, and C having different particle sizes, in order to satisfy the relationship of the formula (2), the external additive particles A, B, and C have different hydrophobizing treatments. It is preferable that when the molecular weight of each hydrophobizing agent is X _A , X _B , X _C , these satisfy the relationship of the following formula (3).
_{X A <X B <X C} ··· (3)

  Since the larger the molecular weight of the hydrophobizing agent, the higher the hydrophobizing ability tends to be, so that the external additive particles A, B, and C can be treated with the hydrophobizing agent having the relationship of the formula (3). This is because it is effective as a method satisfying the relationship of the expression (2).

Here, the molecular weight X is defined as follows.
(1) When the hydrophobizing agent is a coupling agent that reacts with the external additive core When the coupling agent is represented by x-M-R (x is an unbonded functional group, M is Si or Ti, R is a reactive group bonded to the external additive core), and the molecular weight of x is X.
(2) When the hydrophobizing agent is silicone oil, let X be the molecular weight of the silicone oil.
(3) When a plurality of hydrophobizing agents are used as the hydrophobizing agent, the ratio of each component in the mixed hydrophobizing agent is shown as a mole fraction, and each of the hydrophobizing agents (each mole fraction). X molecular weight) is the average molecular weight X of the hydrophobizing agent.

In the present invention, the molecular weight X of each of the hydrophobizing agents to be processed into three external additive particles having different particle diameters is such that X _A of the large-diameter external additive particles is in the range of 15 to 50, and the medium-diameter external additive particles _{X B} in the range of 40 to 150 in, _{X C} of the small-diameter external additive particles is preferably a value greater than 100.
Particularly X _A, it is preferable from the viewpoint of powder fluidity of 50 or less. When X _A is more than 50, there is a case where the flowability is decreased.

In the present invention, as the hydrophobizing agent selected from the above viewpoint, a coupling agent is more suitable than the oil type for the external additive particles A, and hexamethyldisilazane, dimethyldichlorosilane, or the like is used. preferable. For the external additive particle B, it is preferable to use isobutylsilane, hexylsilane or the like. Oil-based high molecular weight particles can be used for the external additive particles C, and dimethyl silicone oil, methylphenyl silicone oil, and the like are preferably used.
In particular, a combination using hexamethyldisilazane for the external additive particles A, isobutylsilane for the external additive particles B, and dimethyl silicone oil for the external additive particles C is most preferable.

  In this case, the treatment amount of the hydrophobizing agent is preferably in the range of 1 to 40 parts by mass with respect to 100 parts by mass of the external additive core. However, the processing amount may not be the same for all the external additive particles A, B, and C.

Examples of the treatment method of various hydrophobizing agents on the external additive core include a treatment method in an aqueous medium, a treatment method in an organic solvent, and a treatment method in a gas phase.
In the method of treatment in the aqueous medium, the external additive core particles to be treated such as inorganic fine particles are dispersed so as to become primary particles, and for example, the treatment is performed while hydrolyzing the silane compound. Moreover, in the case of silicone oil, it processes using an emulsion. In this treatment method, since the external additive core particles to be treated can be produced, the aqueous paste can be dispersed in the aqueous medium without passing through the drying step, so that it is easily dispersed in the primary particles. When processing with several kinds of processing agents, they may be added simultaneously or sequentially.

  The gas phase method is a method of treating the external additive core particles to be treated by dropping or spraying the processing agent while sufficiently stirring mechanically or in an air stream (this is referred to as “gas phase method 1”). ) At this time, the reactor is preferably purged with nitrogen or heated to 50 to 350 ° C. When the viscosity of the treatment agent is high, it may be diluted with a solvent such as alcohol, ketone, or hydrocarbon. Further, ammonia, amine, alcohol, and water may be added to increase the reactivity during the treatment. This treatment method is a preferable method because the reaction is carried out firmly, so that high hydrophobicity and uniformity can be easily obtained.

  As another method of the gas phase method, hydrophobization is performed immediately after the core particles of the external additive to be processed are formed in the carrier gas by the gas phase method (chlorine method, low temperature oxidation method, etc.). There is a method (hereinafter referred to as “gas phase method 2”) in which the processing agent is diluted with a solvent in some cases, and vaporized and atomized to be processed into particles to be processed in the gas phase. In this method, in addition to the advantages of the vapor phase method 1, the treatment is performed before the particles to be treated are united. When processing with several kinds of processing agents, they may be added simultaneously or sequentially.

  The method of treating in the organic solvent is a method in which the external additive core particles to be treated are dispersed in an organic solvent, treated with a hydrophobizing agent, filtered or distilled off, and then dried. In order to reduce agglomerates, it is also preferable to perform a pulverization treatment thereafter with a pin mill or a jet mill. The drying process may be stationary or flowing, and is preferably heated to about 50 to 350 ° C., and may be decompressed. As the organic solvent, hydrocarbon organic solvents such as toluene, xylene, hexane and isopar are preferably used. As a dispersion treatment method, a stirrer, a shaker, a pulverizer, a mixer, and a disperser are used. Among them, a disperser using a medium such as a ball or a bead made of ceramics, agate, alumina, or zirconia is preferably used. It is done. For example, there are a sand mill, a grain mill, a basket mill, a ball mill, a sand grinder, a visco mill, a paint shaker, an attritor, a dyno mill, and a pearl mill.

  Particularly preferred treatment methods include a method in which the external additive core particles to be treated are dispersed in an organic solvent to form a paste, and then the treatment agent is added to the disperser, and the paste in an organic solvent containing the treatment agent is dispersed. There are a method of applying a treating agent and particles to be treated to an organic solvent, a method of applying a paste to a disperser, and a method of adding a treating agent while applying the paste to the disperser. A method of treating in an organic solvent is a preferred method because the particles to be treated can be treated in a dispersed state, coalescence hardly occurs after the treatment, and aggregates hardly occur. When treating with several types of hydrophobizing agents, they may be added simultaneously with the preparation of the slurry, may be added sequentially, or may be added when applied to a disperser. Alternatively, when it is applied to the disperser several times, each time it is applied to the disperser, it may be added in advance when it is added and mixed in the slurry or applied to the disperser.

The above four methods can be used, and the processing agents may be processed simultaneously, or may be processed in several steps in random order. In the case of processing in a plurality of times, any combination of processing methods may be used.
In any process, after the treatment, it is preferable to perform a crushing treatment using a pulverizer such as a pin mill, a hammer mill or a jet mill in order to reduce aggregates.

  When the external additive core is titanium oxide fine particles or alumina fine particles, silane is used to prevent coalescence during processing, to suppress the formation of aggregates, and to achieve uniform hydrophobicity and uniform release properties. Either a compound type treatment agent and a silicone oil type treatment agent can be treated simultaneously (both are added simultaneously as a treatment agent) or treated with a silane compound type treatment agent and then treated with a silicone oil type treatment agent. preferable. As the treatment method, a treatment in an organic solvent and a gas phase method are preferable. Among them, as a preferable method, a method in which a silane compound type treatment agent and a silicone oil type treatment agent are simultaneously treated in an organic solvent, and a gas phase method 2, a silane compound type treatment agent and a silicone oil type treatment agent are used. There are ways to handle them simultaneously. There is also a method of treating a silane compound type treating agent in an aqueous medium, a gas phase method, or an organic solvent with a silicone oil type treating agent in an organic solvent or a gas phase method. Among these methods, it is particularly preferable that the treatment with a silicone oil type treatment agent is performed in an organic solvent.

  Further, when the external additive core is silica, the gas phase method 1 and the gas phase method 2 are preferable. When titanium oxide is used, the aqueous method, the solvent method, and the gas phase method 2 are preferable. Solvent method, gas phase method 1 and gas phase method 2 are preferably used.

In the present invention, when the hydrophobization treatment is performed with the hydrophobizing agent by the method as described above, in the present invention, the external additive particles A, B, and C having different particle diameters are related to the formula (2). to meet, when the processing amount of each of the hydrophobic treatment agent which is processed into an external additive core 100 parts by weight of each of the (parts by mass) M _a, M _B, and M _C, they formula (4) It is preferable to satisfy the relationship.
_{M A <M B <M C} ··· formula (4)

This is because the degree of methanol hydrophobization tends to increase as the treatment amount of the hydrophobizing agent increases, and the relationship of equation (2) can be satisfied by using the relationship of equation (4). In this case, the hydrophobizing agents used for the external additive particles A, B, and C may be the same or different, but the same is preferable for satisfying the relationship of the formula (2). .
The amount of treatment in the present invention is not the amount of the hydrophobic treatment agent actually treated on the external additive particles, but the amount of the hydrophobic treatment agent used for the external additive core during the hydrophobic treatment. Say.

In this case, each of the processing amount M of hydrophobic treatment agent which is processed into three external additive particles having different particle sizes, M _A is 1 to 20 parts by weight range of the large-diameter external additive particles, middle-diameter _{M B} in the range of 3 to 30 parts by weight of the additive particles, _{M C} of the small-diameter external additive particles is preferably in the range of 5 to 40 parts by weight.
Especially M _A is more preferable from the viewpoint of fluidity than 20 parts by mass.

(Other additives)
In addition to the three external additive particles, the toner of the present invention includes inorganic fine particles, a charge control agent, a lubricant, an abrasive, and a cleaning agent for the purpose of improving charging characteristics, powder characteristics, transfer characteristics, and cleaning characteristics. A known additive such as an auxiliary agent may be externally added. Known inorganic fine particles can be used. Examples thereof include silica, alumina, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate. Examples of the resin fine particles include spherical particles such as PMMA, nylon, melamine, benzoguanamine, and fluorine, and amorphous powders such as vinylidene chloride and fatty acid metal orchards. In addition, the surface treatment of the small-diameter inorganic fine particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

  The toner for developing an electrostatic latent image of the present invention can be obtained by mixing toner base particles and external additive particles, but there is no particular limitation on the mixing (blending) method, and it is performed by a known method. Can do. For example, a dry method using a V-type blender, a Henschel mixer, a Redige mixer, a Q-type mixer, a hybridization system, etc. may be used, or when toner base particles are prepared by a wet manufacturing method, they may be blended as they are by a wet method. Good. Moreover, in order to remove the coarse powder generated by blending, it is preferable to sieve after the blending step. The electrostatic latent image developing toner of the present invention may be mixed with a known cleaning auxiliary material, if necessary.

  The addition amount of the three external additive particles A, B, and C is preferably in the range of 0.2 to 4.0 parts by mass with respect to 100 parts by mass of the toner base particles. If the amount is less than 0.2 parts by mass, the function of each particle may not be exhibited. If the amount exceeds 4.0 parts by mass, the toner may not adhere to the surface of the toner base particles, causing peeling or the like, which may cause image quality defects.

More specifically, the coverage F represented by the following formula (5) on the surface of the toner base particles by each external additive particle is preferably in the range of 5 to 80%. If it is less than 5%, the function of each particle is not expressed, and if it exceeds 80%, the function of other external additives may be difficult to be expressed. If all three external additives exceed 80%, the total coverage will exceed 240%. In-machine contamination due to detachment of external additives and output of OHP may deteriorate image transparency. .
F = √3 · D · ρ t (2π · d · ρ a) ⁻¹ · C × 100 (5)
(In the above formula, F is the coverage (%), D is the volume average particle diameter (μm) of the colored particles, ρ t is the true specific gravity of the colored particles, d is the average primary particle diameter (μm) of the external additive, ρ a represents the true specific gravity of the external additive, and C represents the ratio (x / y) of the weight x (g) of the external additive to the weight y (g) of the colored particles.

  In the present invention, three types of external additive particles having different particle diameters are used. In this case, if the small-sized external additive particles adhere to the toner base particles, the fluidity of the toner is improved. Since the external additive fine particles having a diameter are difficult to uniformly adhere to the fine particles, the small external additive particles are preferably added after the large external additive particles. That is, when three or more kinds of external additive particles having different particle diameters are used, it is preferable to add them in order from the largest additive particle having the largest particle diameter.

The electrostatic latent image developing toner of the present invention can be suitably produced by the production method as described above, but is not limited to this production method.
The volume average particle diameter of the toner in the present invention is preferably in the range of 2 to 8 μm, and more preferably in the range of 3 to 6 μm. Moreover, as a number average particle diameter, the range of 2-8 micrometers is preferable. Further, the value of (volume average particle diameter ÷ number average particle diameter), which is an index of particle size distribution, is preferably 1.6 or less, and more preferably 1.5 or less. If this value is larger than 1.6, the spread of the particle size distribution becomes large, so that the distribution of charge amount becomes wide, and reverse polarity toner and low charge toner are likely to be generated.

Further, the toner shape factor SF1 in the present invention is preferably in the range of 110 to 140.
When the shape factor SF1 is less than 110, the blade cleaning property of the transfer residual toner on the photoreceptor is impaired. When the shape factor SF1 exceeds 140, the fluidity of the toner is lowered and the transfer property may be adversely affected from the beginning.

Here, the shape factor SF1 is obtained by the following equation (6).
SF1 = (ML ² / A) × (π / 4) × 100 (6)
In the above formula (6), ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.
The SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and can be calculated as follows, for example. That is, an optical microscope image of the toner dispersed on the surface of the slide glass is taken into a Luzex image analyzer through a video camera, the maximum length and the projected area of 100 or more toner particles are obtained, calculated by the above formula (6), and the average Obtained by determining the value.

The electrostatic latent image developing toner of the present invention can be made into a two-component developer by mixing with a carrier.
As the carrier, it is preferable to use a resin-coated carrier having a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on a core material in terms of charge controllability and resistance controllability. As a volume average particle diameter of a carrier core material, generally 10-100 micrometers is preferable and 20-80 micrometers is more preferable. If it is smaller than 10 μm, the magnetic force per carrier particle is lowered, and carrier skipping may occur easily. If it is larger than 100 μm, there may be a problem that sufficient charge cannot be imparted to the toner or the image deteriorates.

  The core material of the carrier is not particularly limited, and examples thereof include magnetic metals such as iron, steel, nickel and cobalt, magnetic oxides such as ferrite and magnetite, glass beads, and the like, from the viewpoint of using the magnetic brush method. Is preferably a magnetic carrier.

  The coating resin includes polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer. Examples include polymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polyurethanes, polycarbonates, phenol resins, amino resins, melamine resins, benzoguanamine resins, urea resins, amide resins, epoxy resins, etc. However, it is not limited to these.

  The average film thickness of the resin coating layer formed by the above method is usually in the range of 0.1 to 10 μm, and preferably in the range of 0.2 to 5 μm. When the thickness is less than 0.1 μm, the core is easily peeled off, and the core is easily exposed over time, and the charge imparting ability and resistance may be lowered, and stable image quality may not be obtained. When the film thickness exceeds 10 μm, the change with time does not easily occur, but the resistance becomes too high, so that the image quality may be deteriorated. In addition, fluidity may be deteriorated.

  In order to reduce the resistance while increasing the film thickness, the resin matrix may contain conductive powder. Examples of the conductive material include metals such as gold, silver and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, carbon black, magnetite, and the like. Is not to be done.

  The content of the conductive material is preferably 1 to 50 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the matrix resin.

  If the carrier resistance is too low, the carrier adheres to the image area of the photoreceptor due to charge injection from the sleeve, or the latent image charge escapes through the carrier, resulting in a latent image distortion or image loss. Such problems arise. On the other hand, when the carrier resistance is high, the carrier charge is less likely to leak, resulting in an edged image. On the other hand, the edge effect is that the image density at the center is very thin on a large image area. Problems arise.

  Examples of the method for producing the carrier include an immersion method in which the powder of the carrier core material is immersed in a solution for forming the coating layer, a spray method in which the solution for forming the coating layer is sprayed on the surface of the carrier core material, and the carrier core material is fluidized air. The fluidized bed method in which the coating layer forming solution is sprayed in a suspended state, the kneader coater method in which the carrier core material and the coating layer forming solution are mixed in the kneader coater to remove the solvent, and the coating resin is made into fine particles. Examples of the powder coating method include a carrier core material and a kneader coater which are mixed at a melting point or higher and cooled to form a film, and the kneader coater method and the powder coat method are particularly preferably used.

  The mixing ratio (mass ratio) between the electrostatic latent image developing toner of the present invention and the carrier in the two-component developer is preferably in the range of toner: carrier = 1: 100 to 30: 100. : The range of about 100-20: 100 is more preferable.

An image forming method using the electrostatic latent image developing toner of the present invention will be described below.
As an image forming method, for example, a latent image forming step for forming an electrostatic latent image on the surface of the latent image carrier and a developer carried on the developer carrier are used. A developing process for developing the electrostatic latent image to form a toner image, a transfer process for transferring the toner image formed on the surface of the latent image carrier, and a cleaning process for cleaning the toner remaining on the surface of the latent image carrier; And a fixing step of thermally fixing the transferred image. The developer containing the electrostatic latent image developing toner of the present invention is used as the developer.

  The latent image forming step is a step of forming an electrostatic latent image by uniformly charging the surface of the latent image carrier with a charging means and then exposing the latent image carrier with a laser optical system or an LED array. is there. As charging means, a contact-type charger such as corotron or scorotron, and a contact-type charger that charges the surface of the latent image carrier by applying a voltage to a conductive member in contact with the surface of the latent image carrier. Examples of the charger include any charger. However, a contact charging type charger is preferable from the viewpoint that the amount of ozone generated is small, environmentally friendly, and excellent printing durability. In the contact charging type charger, the shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like, but a roller-like member is preferable. The image forming method is not subject to any particular limitation in the latent image forming process.

  The developing step refers to bringing a developer carrier having a developer layer containing at least toner on the surface thereof into contact with or in proximity to the electrostatic latent image on the surface of the latent image carrier. Is a step of forming a toner image on the surface of the latent image carrier. The development method can be performed using a known method, but examples of the development method using a two-component developer include a cascade method and a magnetic brush method. The image forming method is not particularly limited with respect to the development method.

  The cleaning step is a step of removing untransferred toner, paper dust, dust, etc. adhering to the surface of the latent image carrier by bringing a blade, brush, roll, etc. into direct contact with the surface of the latent image carrier. The most commonly employed method is a blade cleaning method in which a rubber blade such as polyurethane is pressed against the latent image carrier. When a toner having a small shape factor and a small particle diameter that is difficult to clean is used, it is effective to increase the resilience of the blade material. In addition, it is possible to select cleaning conditions suitable for each toner by adjusting the hardness of the blade material, the pressing accuracy, the nip amount with respect to the photoreceptor, and the like.

  The fixing step is a step of fixing the toner image transferred to the surface of the recording medium with a fixing device. As the fixing device, a heat fixing device using a heat roll is preferably used. The heat fixing device includes a heater roller for heating inside a cylindrical metal core, a fixing roller in which a so-called release layer is formed by a heat resistant resin coating layer or a heat resistant rubber coating layer on the outer peripheral surface thereof, and the fixing roller. The pressure roller or the pressure belt is disposed in pressure contact with the roller and has a heat-resistant elastic layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. The fixing process of the unfixed toner image is performed by inserting a recording medium on which an unfixed toner image is formed between a fixing roller and a pressure roller or a pressure belt, so that a binder resin, an additive, etc. Fix by heat melting. In the image forming method, the fixing method is not particularly limited.

  The image forming method using the electrostatic latent image developing toner of the present invention is not particularly limited and can be applied to conventionally known image forming apparatuses. As a specific image forming apparatus, for example, a normal monocolor image forming apparatus in which only a single color toner is accommodated in a developing device, or a toner image carried on an image carrier is sequentially subjected to primary transfer to an intermediate transfer member. Examples include a color image forming apparatus that repeats, and a tandem type color image forming apparatus in which a plurality of image carriers each having a developing device for each color are arranged in series on an intermediate transfer member.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” and “%” mean “parts by mass” and “% by mass”.
Production of the electrostatic latent image developing toner, carrier and electrostatic latent image developing developer used in each example and comparative example, and measurement were performed by the following methods.

(Measurement of average primary particle diameter of external additives, volume average particle diameter of resin particles, etc.)
The measurement was performed using a laser diffraction / scattering particle size distribution analyzer (Mastersizer 2000, manufactured by Malvern).
As a measuring method, the sample in the state of dispersion is adjusted so as to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. Regarding the obtained volume particle size distribution for each channel, the volume average particle size is the place where the cumulative particle size is 50% from the smaller particle size, and this is the average primary particle size of the external additive particles in the present invention. .

  When measuring each particle such as external additive particles, 2 g of a measurement sample is added to 50 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, and 2 minutes with an ultrasonic disperser (1000 Hz). A sample was prepared by dispersing, and the sample was measured in the same manner as the above dispersion. The volume average particle diameter of resin particles and the like is also determined according to the above.

(Methanol hydrophobicity)
The degree of methanol hydrophobization in the present invention can be experimentally determined by titrating the hydrophobized external additive particles with methanol as follows.
Take 50 ml of distilled water in a beaker and then gently add 0.20 g of external additive particles. While stirring this mixture with a magnetic stirrer, methanol was dripped little by little from the burette, and when the entire external additive particles floating on the water surface became wet in the solution, the end point was the methanol hydrophobicity W required for methanol. From the dripping amount Q (ml), it is obtained by the following formula (7).
W (%) = [Q / (50 + Q)] × 100 (7)

<Preparation of toner mother particle 1>
-Preparation of resin particle dispersion-
-Styrene 370 parts-N-butyl acrylate 30 parts-Acrylic acid 8 parts-Dodecanethiol 24 parts-Carbon tetrabromide 4 parts A nonionic surfactant (Nonipol 400: 6 parts of Sanyo Chemical Co., Ltd.) and 10 parts of an anionic surfactant (Neogen SC: Daiichi Kogyo Seiyaku Co., Ltd.) were dissolved in 550 parts of ion-exchanged water, and the mixture was slowly mixed for 10 minutes. Then, 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added thereto. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin particle dispersion was obtained in which resin particles having a volume average particle size of 150 nm, Tg = 52 ° C., and weight average molecular weight Mw = 10500 were dispersed. The solid content concentration of this dispersion was 40% by mass.

-Preparation of colorant dispersion (1)-
・ Carbon black (Mogal L: Cabot) 60 parts ・ Nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd.) 6 parts ・ Ion-exchanged water 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer and a colorant having a volume average particle diameter of 250 nm ( A colorant dispersant (1) having carbon black particles dispersed therein was prepared.

-Preparation of colorant dispersion (2)-
・ Cyan pigment (CI Pigment Blue 15: 3) 60 parts ・ Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) 5 parts ・ Ion-exchanged water 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer and a colorant having a volume average particle diameter of 250 nm ( Cyan pigment) A colorant dispersant (2) in which particles were dispersed was prepared.

-Preparation of colorant dispersion (3)-
・ Magenta pigment (CI Pigment Red 122) 60 parts ・ Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) 5 parts ・ Ion-exchanged water 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer and a colorant having a volume average particle diameter of 250 nm ( Magenta pigment) A colorant dispersant (3) in which particles were dispersed was prepared.

-Preparation of colorant dispersion (4)-
・ Yellow pigment (CI Pigment Yellow 180) 90 parts ・ Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) 5 parts ・ Ion-exchanged water 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer and a colorant having an average particle size of 250 nm (Yellow) A colorant dispersant (4) in which (pigment) particles were dispersed was prepared.

-Release agent dispersion-
Paraffin wax (HNP0190: manufactured by Nippon Seiwa Co., Ltd., melting point 85 ° C.) 100 parts Cationic surfactant (Sanisol B50: manufactured by Kao Corporation) 5 parts Ion-exchanged water 240 parts

  The above components are dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge homogenizer, and the volume average particle diameter is 550 nm. A release agent dispersion liquid in which release agent particles are dispersed was prepared.

(Toner mother particle K1)
-Resin particle dispersion 234 parts-Colorant dispersion (1) 30 parts-Release agent dispersion 50 parts-Polyaluminum chloride (Paho2S, manufactured by Asada Chemical Co., Ltd.) 0.5 parts-Ion-exchanged water 600 parts

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then heated to 40 ° C. while stirring the flask in a heating oil bath. . After maintaining at 40 ° C. for 30 minutes, it was confirmed that aggregated particles having a D50 of 4.5 μm were produced. Further, the temperature of the applied oil bath was raised and maintained at 56 ° C. for 1 hour, and D50 was 5.3 μm. Thereafter, 26 parts by mass of a resin particle dispersion was added to the dispersion containing the aggregate particles, and then the temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes. The dispersion containing the aggregated particles was added with 1N sodium hydroxide to adjust the pH of the system to 7.0, and then the stainless steel flask was sealed and heated to 80 ° C. while continuing stirring using a magnetic seal. And held for 4 hours. After cooling, the toner base particles were separated by filtration, washed four times with ion exchange water, and then lyophilized to obtain toner base particles K1. The toner base particle K1 had a particle size of 5.9 μm, a volume average particle size of 5.9 μm, and a shape factor SF1 of 132.

(Toner mother particle C1)
Toner base particles C1 were obtained in the same manner as the toner base particles K1, except that the colorant dispersion liquid (2) was used instead of the colorant dispersion liquid (1). The toner base particle C1 had a particle size of 5.8 μm, a volume average particle size of 5.8 μm, and a shape factor SF1 of 131.

(Toner mother particle M1)
Toner base particles M1 were obtained in the same manner as toner base particles K1 except that the colorant dispersion liquid (3) was used instead of the colorant dispersion liquid (1). The toner base particles M1 have a volume average particle size of 5.5 μm and a shape factor SF1 of 135.

(Toner mother particle Y1)
Toner base particles Y1 were obtained in the same manner as the toner base particles K1, except that the colorant dispersion liquid (4) was used instead of the colorant dispersion liquid (1). The toner base particle Y1 has a volume average particle size of 5.9 μm and a shape factor SF1 of 130.

<Preparation of toner mother particles 2>
-Synthesis of crystalline polyester resin (1)-
In a heat-dried three-necked flask, 17.4 parts of 1,10-decanediol, 2.2 parts of sodium dimethyl 5-sulfoisophthalate, 10 parts of dimethyl sulfoxide, 0.03 part of dibutyltin oxide as a catalyst, After that, the air in the container was replaced with nitrogen gas by a depressurization operation to create an inert atmosphere, and the mixture was stirred at 180 ° C. for 3 hours by mechanical stirring. Dimethyl sulfoxide was distilled off under reduced pressure, 26.5 parts of dimethyl dodecanedioic acid was added under a nitrogen stream, and the mixture was stirred at 180 ° C. for 1 hour.

Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 30 minutes. When it became viscous, it was air-cooled to stop the reaction, and 36 parts of crystalline polyester resin (1) was synthesized. The crystalline polyester resin (1) obtained had a weight average molecular weight (M _W ) of 9,200 and a number average molecular weight (M _n ) of 6,000 as determined by gel permeation chromatography.

  Further, when the melting point (Tm) of the crystalline polyester resin (1) was measured by a differential scanning calorimeter (DSC) by the above-described measuring method, it had a clear peak and the peak top temperature was 79 ° C. Met. The content ratio of the copolymerization component (5-sulfoisophthalic acid component) and the dodecanedioic acid component measured and calculated from the NMR spectrum of the resin was 7.5: 92.5.

(Toner mother particle C2)
-Preparation of resin particle dispersion (1)-
150 parts of the obtained crystalline polyester resin (1) was put into 850 parts of distilled water, and mixed and stirred with a homogenizer (manufactured by IKA Japan: Ultra Tarax) while heating to 85 ° C. to obtain a resin particle dispersion ( 1) was obtained.

-Preparation of colorant dispersion (5)-
Mixing 250 parts of phthalocyanine pigment (manufactured by Dainichi Seika Co., Ltd .: PV FAST BLUE), 20 parts of anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK), and 730 parts of ion-exchanged water Then, after being dissolved, it was dispersed using a homogenizer (manufactured by IKA: Ultra Tarax) to prepare a colorant dispersion (5) in which a colorant (phthalocyanine pigment) was dispersed.

-Preparation of aggregated particles-
2400 parts of resin particle dispersion (1), 100 parts of colorant dispersion (5), 63 parts of release agent dispersion, 10 parts of lauroyl peroxide, 5 parts of aluminum sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) , 100 parts of ion-exchanged water are contained in a round stainless steel flask, adjusted to pH 2.0, dispersed using a homogenizer (IKA Corporation: Ultra Turrax T50), and then in a heating oil bath At 72 ° C. with stirring. After maintaining at 72 ° C. for 3 hours, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.0 μm were formed. After further heating and stirring at 72 ° C. for 1 hour, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.5 μm were formed.

-Fusion process-
The pH of the aggregated particles was 2.4. Therefore, an aqueous solution obtained by diluting sodium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) to 0.5% by weight was gently added to adjust the pH to 5.0. did.

  Thereafter, the reaction product was filtered, sufficiently washed with ion-exchanged water, and then dried using a vacuum drier to obtain toner base particles C2. The obtained toner base particles C2 were measured for volume average particle size using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter), and the D50 of the toner base particles C2 was 5.5 μm. The shape factor SF1 was 131.

<Creation of carrier>
14 parts of toluene, 2 parts of styrene-methyl methacrylate copolymer (component ratio: 80/20, weight average molecular weight 70000), and 0.2 part of carbon black (R330: manufactured by Cabot) are mixed and stirred with a stirrer for 10 minutes. Thus, a coating layer forming solution in which carbon black was dispersed was prepared. Next, this coating solution and 100 parts of ferrite particles (volume average particle size: 38 μm) are put in a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. The carrier was prepared by drying. This carrier had a volume resistivity of 10 ¹¹ Ωcm when an electric field of 800 V / cm was applied.

<Hydrophobicization treatment of external additive particles>
The hydrophobic treatment of the external additive particles was performed as follows. Silane and a silane coupling agent were used as the treating agent.
In a reaction vessel, 80 parts of an external additive core is added to a mixed solvent in which 1000 parts of pure water and 100 parts of 2-propanol are mixed to form a slurry. Next, with respect to 100 parts of the external additive core, the processing agent types shown in Table 1 below were charged in the same amount as shown in Table 1 into a slurry reaction vessel. After replacing the inside of the reaction vessel with dry nitrogen gas, the temperature was raised, 30 parts of 0.1N HCl was added dropwise, and the mixed solution was heated to about 80 ° C. while stirring under a nitrogen gas stream.

Thereafter, the reaction was stirred for 3 hours while heating and refluxing in an oil bath. After cooling, the mixed solution was taken out, fine particles were separated by a centrifuge, and the supernatant was removed. The operation of mixing and stirring the filtered fine particles in a 10% aqueous methanol solution and centrifuging was repeated three times. Furthermore, after mixing and stirring in pure water and repeating the centrifugation operation three times, the fine particle wet product was lyophilized to remove moisture. After vacuum drying at 160 ° C. for 2 hours, the mixture was crushed with an agate mortar and sieved with a 40 μm sieve mesh.
As described above, external additives I to VI including three types of external additive particles were obtained.

<Example 1>
For 100 parts of each of the toner base particles K1, C1, M1, and Y1, 0.5 parts of the small-diameter external additive I, 1.0 part of the medium-sized external additive, and 1.0 part of the large-diameter outside of Table 1 are used. 1.0 part of each additive was added, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles were removed using a sieve having a mesh opening of 45 μm, and toner 1 was removed. Produced.

<Example 2>
For each 100 parts of the toner base particles K1, C1, M1, and Y1, 0.5 parts of the small-diameter external additive II, 1.0 part of the medium-sized external additive and 1.0 part of the large-diameter outside of Table 1 are used. 1.0 parts of each additive was added, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles were removed using a sieve having a mesh opening of 45 μm, and toner 2 was removed. Produced.

<Example 3>
For 100 parts of each of the toner base particles K1, C1, M1, and Y1, 0.5 part of the small-diameter external additive III, 1.0 part of the medium-diameter external additive in Table 1, 1.0 part of each additive was added, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles were removed using a sieve having a mesh opening of 45 μm, and toner 3 was removed. Produced.

<Example 4>
For 100 parts of each of the toner base particles K1, C1, M1, and Y1, 0.5 parts of the small-diameter external additive IV, 1.0 part of the medium-sized external additive and 1.0 part of the large-diameter outside of Table 1 are used. 1.0 part of each additive was added, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles were removed using a sieve having a mesh opening of 45 μm, and toner 4 was removed. Produced.

<Example 5>
For 100 parts of the toner base particles C2, 0.5 parts of the small-diameter external additive, 1.0 part of the medium-sized external additive, and 1.0 part of the large-diameter external additive of Table 1 are shown. After adding and blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles were removed using a sieve having an opening of 45 μm to prepare toner 5.

<Comparative Example 1>
For 100 parts of each of the toner base particles K1, C1, M1, and Y1, 0.5 parts of the small diameter external additive V, 1.0 part of the medium diameter external additive, and 1.0 part of the large diameter external additive of Table 1 are added. 1.0 part of each agent was added, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then coarse particles were removed using a sieve with a mesh opening of 45 μm to prepare toner 6. did.

<Comparative example 2>
To 100 parts of each of the toner base particles K1, C1, M1, and Y1, 0.5 parts of the small-diameter external additive VI and 1.0 part of the large-diameter external additive shown in Table 1 are added. After blending for 15 minutes at a peripheral speed of 30 m / s using a liter Henschel mixer, coarse particles were removed using a sieve having an opening of 45 μm to prepare toner 7.

<Production of developer>
10 parts of each of the obtained toners 1 to 7 and 100 parts of the carrier are stirred with a V-blender at 40 rpm for 20 minutes and sieved with a sieve having an opening of 212 μm, thereby developing an electrophotographic developer for color. 1-7 were produced.

<Evaluation>
The developers shown in Examples and Comparative Examples were evaluated as follows.
Each of the above developers was used, and DocuCenterColor400 (Fuji Xerox Co., Ltd.) was used as the apparatus.
(Output image)
As an actual machine image output method, a gradation chart of four colors was used. As the gradation chart, “A4 size chart (20%) for each color of image density (A)” and “A4 size chart (3% for each color of image density) (B)” were used. The image density is adjusted by the area ratio of the image portion. Each gradation chart has a solid portion, a halftone portion, and a background portion.

(Charging characteristics evaluation)
(1) The gradation chart A is output under high temperature and high humidity (30 ° C./80% RH), and the developer on the mag roll after 100 sheets (initial) and the mag roll after 5,000 sheets (after durability) The developer was collected and the charge was measured.
(2) Output gradation chart B under low temperature and low humidity (10 ° C / 10% RH), collect developer on mag roll after 100 sheets and developer on mag roll after 5,000 sheets, and measure charge Carried out.
The charge amount was measured by a blow-off method using a charge amount measuring device TB-200 (manufactured by Toshiba). The measurement conditions at this time were blow-off gas with air at a pressure of 1.0 kg / cm ³ and a measurement sample amount of 0.2 g. The evaluation results are shown only for Cyan.

  The charge amount was measured by measuring the charge amount by a blow-off method using a Faraday cage and evaluating the environmental difference. When the environmental difference “(high temperature and high humidity charge amount) ÷ (low temperature and low humidity charge amount)” is 0.7 or more, “◯” is given, and when it is less than 0.7, “x” is given.

(Liquidity assessment)
For the evaluation of fluidity, a powder rheometer was used. A measurement method will be described.
The powder rheometer is a fluidity measuring device that directly measures fluidity by simultaneously measuring rotational torque and vertical load obtained by rotating a rotating blade spirally in packed particles. By measuring both the rotational torque and the vertical load, the fluidity including the characteristics of the powder itself and the influence of the external environment can be detected with high sensitivity. In addition, since the measurement is performed with the particle filling state kept constant, data with good reproducibility can be obtained.

  In this invention, it measured using FT4 made from freeman technology as a powder rheometer. In order to eliminate the influence of temperature and humidity before the measurement, a developer was used that was allowed to stand for 8 hours or more at a temperature of 22 ° C. and a humidity of 50% RH.

  Putting toner in a 200 mL container with an inner diameter of 50 mm and a height of 140 mm, and moving air at an entrance angle of -5 ° from the bottom to a height of 110 mm to 10 mm while allowing air to flow in at a flow rate of 50 ml / min. Rotational torque and vertical load when rotating at a tip speed of 100 mm / s are measured.

  Here, the measurement is performed while flowing air at 50 ml / min in order to more closely approximate the toner flow state in the developing device. The toner at 50 ml / min is considered to reproduce the fluid state immediately after being stirred by the stirring member. In the FT4 manufactured by freeman technology, the inflow state of the air flow rate is specified.

The energy gradient (mJ / mm) with respect to the height H is obtained from the rotational torque or vertical load with respect to the height H from the bottom surface, and the area obtained by integrating the energy gradient is the total energy amount (mJ). . In the present invention, the total energy amount was obtained by integrating the section from 10 mm to 110 mm in height from the bottom surface.
In the present invention, in order to reduce the influence of errors, the average value obtained by performing this conditioning and energy measurement cycle five times is defined as the total energy amount (mJ) in the present invention.
As the rotor blade, a two-blade propeller type φ48 mm diameter blade manufactured by freeman technology was used.

  A sample having a total energy amount (mJ) measured under the above conditions of 25 mJ or less was evaluated as ○, and a sample having a total energy exceeding 25 mJ was evaluated as ×.

(Transferability evaluation)
A gradation chart was output under high temperature and high humidity, and the transfer rate was measured with a developer on a mag roll after 100 sheets (initial) and a developer using Cyan toner after 5,000 sheets.
The measurement is performed by developing a solid patch of 5 × 2 cm and measuring the mass (W1) of the developed image on the photoreceptor by tape transfer. Next, the same patch is transferred to the intermediate transfer member, and the mass (W2) of the transferred image is measured. Further, a similar solid patch is transferred onto paper (J paper, manufactured by Fuji Xerox Office Supply), and the mass (W3) of the transferred image is measured. By each measured value, developability is evaluated by W1, and according to the formula {(primary transfer efficiency) = W2 / W1 × 100 (%)}, {(secondary transfer efficiency) = W3 / W2 × 100 (%)}. The primary and secondary transfer efficiencies were determined and the transferability was evaluated. Evaluation conditions were primary transfer current: 20 μA, secondary transfer voltage: 1.5 kV, the developing machine was placed in black, printed in black mode, and evaluated.

Judgment criteria for evaluation of transferability are as follows.
○: primary transfer efficiency / secondary transfer efficiency is 97% or more Δ: primary transfer efficiency / secondary transfer efficiency is 95% or more and less than 97% ×: primary transfer efficiency / secondary transfer efficiency is less than 95% or more The evaluation results are summarized in Table 2.

  As shown in Table 2, when three kinds of external additives having different particle diameters are used for the toner base particles, the aging fluidity is increased by increasing the degree of methanol hydrophobization in order from the largest diameter to the smallest diameter as in the examples. It can be seen that it is possible to obtain a toner with high transfer efficiency that is resistant to fluctuations in stress and has no change in charging with time. On the other hand, when the degree of hydrophobicity of methanol in Comparative Example 1 was not in the order as in the present invention, there was a problem in either charging characteristics or fluidity. Further, in Comparative Example 2 in which no medium-diameter external additive was used, transfer maintenance was deteriorated.

Claims (3)

An electrostatic latent image developing toner having toner base particles and external additive particles containing a binder resin and a colorant,
The external additive particles are three types of external additive particles A, B, and C having different particle diameters, and the average primary particle diameter of each external additive particle is R _A , R _B , and R _C. when methanol hydrophobizing degree of the _{(%) W a, W B} , and W _C, they formula (1) and the electrostatic latent image developing toner characterized by satisfying the relationship of formula (2).
_{R A> R B> R C} ··· Equation (1)
_{W A <W B <W C} ··· formula (2) The three types of external additive particles A, B, and C are hydrophobized by different hydrophobizing agents, and when the molecular weight of each hydrophobizing agent is X _A , X _B , and X _C , The electrostatic latent image developing toner according to claim 1, wherein the following formula (3) is satisfied.
_{X A <X B <X C} ··· (3) The three external additive particles A, B, C are hydrophobic treatment by hydrophobic treatment agent, the process amount of hydrophobic treatment agent for the external additive core 100 parts by mass in each of (parts by weight) M _A , M _B, when the M _C, electrostatic latent image developing toner according to claim 1 to which they are characterized by satisfying the relation of the following formula (4).
_{M A <M B <M C} ··· formula (4)