JP5381949B2 - Toner for electrostatic image development - Google Patents

Description

  The present invention is an electrostatic charge image developing toner (hereinafter, sometimes simply referred to as “toner”) used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like. About.

  In an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and an electrostatic printing apparatus, a desired image is formed by developing an electrostatic latent image formed on a photoreceptor with toner for developing an electrostatic image. This technique is widely used. Such a technique is applied to a copying machine, a printer, a facsimile machine, and a multifunction machine of these.

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

The toner used for development includes a negatively chargeable toner and a positively chargeable toner. An electrophotographic apparatus using a positively chargeable toner has been used preferably in recent years because it generates less ozone and provides good chargeability.
Further, on the surface of toner particles used for development, in order to improve the charging stability, fluidity, durability and the like of the toner, inorganic fine particles and organic fine particles generally having a smaller particle diameter than colored resin particles (toner particles). External additives such as these are externally added (attached).

  In a toner using a conventional external additive, in the process of continuous printing of a large number of sheets, the external additive may be caused by mechanical stress in the developing device (increased number of contact between toner particles due to stirring or the like). The toner particles are buried inside and / or released (desorbed) from the surface of the toner particles. For this reason, the function of the external additive is lowered, and it becomes difficult to impart to the toner particles a stable charging property (charging stability) over time.

  In addition, the toner particles embedded with the external additive cause a phenomenon (filming phenomenon) in which the toner particles adhere to the surface of the photoreceptor, and image quality is likely to be deteriorated due to fogging or the like. The external additive released (desorbed) from the surface of the toner particles deteriorates the charging characteristics of the surface of the photoreceptor, and causes the printing durability and image quality of the toner to deteriorate. Especially under high temperature and high humidity conditions, the image quality is significantly deteriorated by filming.

Therefore, even when the number of contact between the toner particles by stirring or the like increases in the developing device as in the case of continuous printing of a large number of sheets, problems such as embedding and / or releasing of the external additive do not occur. There is a demand for a toner that maintains a state in which an external additive is suitably attached over time and maintains a stable chargeability (charging stability).
Patent Document 1 discloses a toner using inorganic / organic composite fine particles in which inorganic fine particles are fixed on the surface of organic fine particles as an external additive. Patent Document 2 discloses a toner containing resin fine particles having a specific average particle diameter and having a surface covered with a continuous layer of silica as an external additive.

Japanese Patent Laid-Open No. 2002-131976 JP 2005-173480 A

  In Patent Document 1, in paragraph [0064] of the specification of the document, as a means for fixing inorganic fine particles to the surface of organic fine particles, a method of mixing organic fine particles and inorganic fine particles and then applying heat, organic fine particles It is described that a so-called mechanochemical method or the like for mechanically fixing inorganic fine particles to the surface is used. However, with such a manufacturing method, it is difficult to cover the entire surface of the organic fine particles serving as the core with inorganic fine particles. Further, as a result of studies by the present inventors, it has been found that the toner described in Patent Document 1 is likely to cause fogging, particularly fogging under high temperature and high humidity.

  Claim 6 of Patent Document 2 describes that the abundance ratio of silicon atoms on the surface of the external additive is 0.1 to 10.0% by mass. However, in such an external additive, since the thickness of the silica shell is too thin, the contribution of the effect of the silica shell to the entire external additive is small, and therefore, the chargeability in a low temperature and low humidity environment is hardly exhibited.

  An object of the present invention is to provide a toner for developing an electrostatic charge image that suppresses generation of fog in a high temperature and high humidity environment and is excellent in fine line reproducibility in a low temperature and low humidity environment.

  The present inventors diligently studied to achieve the above object, and as an external additive, by using core-shell composite fine particles in which the surface of the resin fine particles is coated with alumina, titania and / or zirconia, Increase in environmental stability of the toner, in particular, increase in the toner charge amount in a low temperature and low humidity environment can be suppressed, stable printing can be performed without losing fine line reproducibility in the same environment, and The present inventors have found that there is no printing defect caused by the rise and that a good image quality can be obtained, and the present invention has been completed.

That is, the toner for developing an electrostatic charge image of the present invention is a toner for developing an electrostatic charge image containing a colored resin particle containing a binder resin and a colorant, and an external additive, and the resin as the external additive The surface of the fine particles contains core-shell type composite fine particles coated with a continuous layer of at least one inorganic component selected from the group consisting of alumina and titania.

  In this invention, it is preferable that the volume ratio of the said inorganic component in the said composite microparticles when the whole volume of the said core-shell type composite microparticles is 100 volume% is 25-75 volume%.

  In the present invention, it is preferable that the adsorbed moisture content of the core-shell type composite fine particles is 0.5 to 2.5 mass%.

  In this invention, it is preferable that the addition amount of the said core-shell type composite fine particle is 0.1-2.0 mass parts with respect to 100 mass parts of the said colored resin particles.

  In the present invention, the number average particle size of the core-shell composite fine particles is preferably 30 to 300 nm.

  In the present invention, the colored resin particles preferably have a volume average particle size of 4 to 12 μm and an average circularity of 0.96 to 1.00.

  In the present invention, the resin fine particles constituting the core-shell type composite fine particles are preferably a crosslinked resin.

  According to the toner for developing an electrostatic charge image of the present invention as described above, by using core-shell type composite particles in which the surface of resin fine particles is coated with alumina, titania and / or zirconia as an external additive, An increase in toner charge amount in a low-humidity environment is suppressed, stable printing can be performed without impairing fine line reproducibility even in the same environment, and there are no print defects caused by an increase in charge amount, resulting in good image quality An electrostatic charge image developing toner is obtained.

  The toner for developing an electrostatic charge image of the present invention is a toner for developing an electrostatic charge image containing a colored resin particle containing a binder resin and a colorant, and an external additive. It is characterized by containing core-shell type composite particles coated on the surface with at least one inorganic component selected from the group consisting of alumina, titania and zirconia.

Hereinafter, the toner for developing an electrostatic charge image of the present invention (hereinafter sometimes simply referred to as “toner”) will be described.
The toner of the present invention contains colored resin particles containing a binder resin and a colorant, and core-shell type composite particles in which the surface of the resin fine particles is coated with alumina, titania and / or zirconia as an external additive.
The toner of the present invention is preferably obtained by adhering and adding the core-shell type composite fine particles as an external additive to the surface of the colored resin particles.
Hereinafter, a method for producing colored resin particles used in the present invention, a colored resin particle obtained by the production method, a method for producing core-shell composite fine particles used as an external additive in the invention, and a core shell obtained by the production method The production method of the toner of the present invention using the mold composite fine particles, the colored resin particles and the external additive, and the toner of the present invention will be described in order.

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

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

  The colored resin particles of the present invention can be produced by employing a wet method or a dry method. Among the wet methods, a preferred suspension polymerization method is adopted, and the following process is performed.

(A) Suspension polymerization method (A-1) Preparation step of polymerizable monomer composition First, a polymerizable monomer, a colorant, and a charge control agent and a release agent added as necessary. Other additives are mixed to prepare a polymerizable monomer composition. The mixing at the time of preparing the polymerizable monomer composition is performed using, for example, a media type dispersing machine.

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

In order to improve hot offset and storage stability, it is preferable to use any crosslinkable polymerizable monomer together with the monovinyl monomer. A crosslinkable polymerizable monomer means a monomer having two or more polymerizable functional groups. Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; alcohols having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; Examples include ester compounds in which two or more carboxylic acids are ester-bonded; other divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups. These crosslinkable polymerizable monomers can be used alone or in combination of two or more.
In the present invention, the crosslinkable polymerizable monomer is usually used at a ratio of 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the monovinyl monomer. desirable.

  Furthermore, it is preferable to use a macromonomer as a part of the polymerizable monomer because the balance between the storage stability of the obtained toner and the fixing property at low temperature is improved. The macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain, and is a reactive oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000. The macromonomer is preferably one that gives a polymer having a higher Tg than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer (hereinafter sometimes referred to as “Tg”). The macromonomer is preferably used in an amount of 0.03 to 5 parts by mass, more preferably 0.05 to 1 part by mass, with respect to 100 parts by mass of the monovinyl monomer.

In the present invention, a colorant is used. However, when producing a color toner, black, cyan, yellow, and magenta colorants can be used.
As the black colorant, carbon black, titanium black, magnetic powder such as iron zinc oxide and nickel iron oxide can be used.

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

  Examples of the yellow colorant include monoazo pigments, azo pigments such as disazo pigments, and compounds such as condensed polycyclic pigments. I. Pigment yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 83, 93, 97, 120, 138, 155, 180, 181, 185, and 186.

  As the magenta colorant, monoazo pigments, azo pigments such as disazo pigments, and compounds such as condensed polycyclic pigments are used. I. Pigment Red 31, 48, 57: 1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 149, 150, 163, 170, 184, 185, 187, 202, 206, 207, 209, 237, 251, 269 and C.I. I. Pigment violet 19 and the like.

  In the present invention, each colorant can be used alone or in combination of two or more. The amount of the colorant is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the monovinyl monomer.

As other additives, a positively or negatively chargeable charge control agent can be used to improve the chargeability of the toner.
The charge control agent is not particularly limited as long as it is generally used as a charge control agent for toner, but among charge control agents, the compatibility with the polymerizable monomer is high, and stable chargeability. (Charge stability) can be imparted to the toner particles, and therefore a positively or negatively chargeable charge control resin is preferred. Further, from the viewpoint of obtaining a positively chargeable toner, a positively chargeable charge control resin is preferred. More preferably used.
Examples of positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds and imidazole compounds, polyamine resins as charge control resins that are preferably used, and quaternary ammonium group-containing copolymers. , And quaternary ammonium base-containing copolymers.
Negatively chargeable charge control agents include azo dyes containing metals such as Cr, Co, Al, and Fe, salicylic acid metal compounds and alkylsalicylic acid metal compounds, and sulfonic acid group containing charge control resins that are preferably used Examples thereof include a copolymer, a sulfonate group-containing copolymer, a carboxylic acid group-containing copolymer, and a carboxylic acid group-containing copolymer.
In the present invention, the charge control agent is usually used in a proportion of 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass, with respect to 100 parts by mass of the monovinyl monomer. If the addition amount of the charge control agent is less than 0.01 parts by mass, fog may occur. On the other hand, when the addition amount of the charge control agent exceeds 10 parts by mass, printing stains may occur.

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

Furthermore, it is preferable to add a release agent as another additive. By adding a release agent, the releasability of the toner from the fixing roll during fixing can be improved. Any releasing agent can be used without particular limitation as long as it is generally used as a releasing agent for toner. For example, low molecular weight polyolefin wax and its modified wax; plant-based natural wax such as jojoba; petroleum wax such as paraffin; mineral wax such as ozokerite; synthetic wax such as Fischer-Tropsch wax; polyglycerin ester, dipentaerythritol ester, etc. And the like. A polyhydric alcohol ester is preferable because the storage stability of the toner and the low-temperature fixability can be balanced. These may be used alone or in combination of two or more.
The release agent is preferably used in an amount of 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the monovinyl monomer.

(A-2) Suspension step for obtaining a suspension (droplet formation step)
In the present invention, a polymerizable monomer composition containing a polymerizable monomer and a colorant is dispersed in an aqueous medium containing a dispersion stabilizer, a polymerization initiator is added, and then the polymerizable monomer composition is added. Droplet formation is performed. The method for forming droplets is not particularly limited. For example, an (in-line type) emulsifying disperser (trade name “Milder” manufactured by Ebara Manufacturing Co., Ltd.), a high-speed emulsifying disperser (trade name “T. K. Homomixer MARK Type II ") or the like capable of strong stirring.

  As a polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate: 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-methyl-N- (2- Hydroxyethyl) propionamide), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), and 2,2′-azobisisobutyro Azo compounds such as nitrile; di-t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylbutanoate, diisopropyl peroxydicarbonate, And organic peroxides such as di-t-butylperoxyisophthalate and t-butylperoxyisobutyrate. That. These can be used alone or in combination of two or more. Among these, it is preferable to use an organic peroxide because residual polymerizable monomers can be reduced and printing durability is excellent.

  Among organic peroxides, peroxyesters are preferred because of the high initiator efficiency and the remaining polymerizable monomer can be reduced. Non-aromatic peroxyesters, that is, peroxyesters having no aromatic ring Is more preferable.

  As described above, the polymerization initiator may be added before the droplet formation after the polymerizable monomer composition is dispersed in the aqueous medium. However, the polymerization initiator is not dispersed in the aqueous medium. It may be added to the monomer composition.

  The addition amount of the polymerization initiator used for the polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 100 parts by mass of the monovinyl monomer. It is -15 mass parts, Most preferably, it is 1-10 mass parts.

  In the present invention, the aqueous medium refers to a medium containing water as a main component.

  In the present invention, the aqueous medium preferably contains a dispersion stabilizer. Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metals such as aluminum oxide and titanium oxide. Oxides; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds such as; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; Organic compounds such as nonionic surfactants; amphoteric surfactants; The said dispersion stabilizer can be used 1 type or in combination of 2 or more types.

  Among the above dispersion stabilizers, inorganic compounds, particularly colloids of poorly water-soluble metal hydroxides are preferred. By using a colloid of an inorganic compound, particularly a poorly water-soluble metal hydroxide, the particle size distribution of the colored resin particles can be narrowed, and the residual amount of the dispersion stabilizer after washing can be reduced. The polymerized toner can reproduce an image clearly and does not deteriorate environmental stability.

(A-3) Polymerization step As in (A-2) above, droplet formation is performed, the resulting aqueous dispersion medium is heated to initiate polymerization, and an aqueous dispersion of colored resin particles is formed.
The polymerization temperature of the polymerizable monomer composition is preferably 50 ° C. or higher, more preferably 60 to 95 ° C. The polymerization reaction time is preferably 1 to 20 hours, more preferably 2 to 15 hours.

  The colored resin particles may be used as a polymerized toner by adding an external additive as it is, but the so-called core-shell type obtained by using the colored resin particles as a core layer and forming a shell layer different from the core layer on the outside thereof. It is preferable to use colored resin particles (also referred to as “capsule type”). The core-shell type colored resin particles balance the reduction of the fixing temperature and the prevention of aggregation during storage by coating the core layer made of a material having a low softening point with a material having a higher softening point. be able to.

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

A method for producing core-shell type colored resin particles by in situ polymerization will be described below.
Addition of a polymerizable monomer (polymerizable monomer for shell) and a polymerization initiator to form a shell layer into an aqueous medium in which colored resin particles are dispersed, and then polymerize to form a core-shell type color. Resin particles can be obtained.

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

  As a polymerization initiator used for polymerization of the polymerizable monomer for shell, persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) Water-soluble such as azo initiators such as) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); A polymerization initiator can be mentioned. These can be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer for shell.

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

(A-4) Washing, filtration, dehydration, and drying steps The aqueous dispersion of colored resin particles obtained by polymerization is washed, dehydrated, and filtered to remove the dispersion stabilizer according to a conventional method after completion of the polymerization. The drying operation is preferably repeated several times as necessary.

  As the above washing method, when an inorganic compound is used as the dispersion stabilizer, the dispersion stabilizer can be dissolved in water and removed by adding an acid or alkali to the aqueous dispersion of colored resin particles. preferable. When a colloid of a poorly water-soluble inorganic hydroxide is used as the dispersion stabilizer, it is preferable to adjust the pH of the colored resin particle aqueous dispersion to 6.5 or less by adding an acid. As the acid to be added, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. Particularly, since the removal efficiency is large and the burden on the manufacturing equipment is small, Sulfuric acid is preferred.

  Various known methods and the like can be used as the method of dehydration and filtration, and there is no particular limitation. Examples thereof include a centrifugal filtration method, a vacuum filtration method, and a pressure filtration method. Also, the drying method is not particularly limited, and various methods can be used.

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

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

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

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

  The volume average particle diameter (Dv) of the colored resin particles is preferably 4 to 12 μm, and more preferably 5 to 10 μm. When Dv is less than 4 μm, the fluidity of the polymerized toner is lowered, and transferability may be deteriorated or the image density may be lowered. When Dv exceeds 12 μm, the resolution of the image may decrease.

  The colored resin particles have a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of preferably 1.0 to 1.3, more preferably 1. 0-1.2. If Dv / Dn exceeds 1.3, transferability, image density, and resolution may decrease. The volume average particle diameter and the number average particle diameter of the colored resin particles can be measured using, for example, a particle size analyzer (trade name “Multisizer” manufactured by Beckman Coulter).

From the viewpoint of image reproducibility, the average circularity of the colored resin particles of the present invention is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and 0.98 to More preferably, it is 1.00.
When the average circularity of the colored resin particles is less than 0.96, the fine line reproducibility of printing may be deteriorated.

  In the present invention, the circularity is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle. The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles. The average circularity is determined by the colored resin particles. 1 is shown in the case of a perfect sphere, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated.

  The colored resin particles preferably exhibit positive chargeability. If negatively charged colored resin particles are used, the charge amount of the toner may be reduced and fogging may occur easily.

3. Production method of core-shell type composite fine particles Core-shell type composite fine particles (hereinafter sometimes simply referred to as “composite fine particles”) used as an external additive in the present invention are easily obtained by using resin fine particles as core particles. The diameter can be controlled, and further, the true specific gravity can be controlled low because it can be adjusted without firing by coating with an inorganic oxide by a sol-gel method which is a preferred method described later. Further, since the core particles are resin fine particles, the core particles are relatively soft and damage to the photoreceptor is reduced.

The core-shell type composite fine particles in which the surface of the resin fine particles used in the present invention is coated with at least one inorganic component selected from the group consisting of alumina, titania and zirconia (hereinafter sometimes referred to as inorganic components) Ii) Whether a commercially available product is used, or ii) a commercially available resin fine particle coated with the above inorganic component, iii) a resin fine particle is produced by polymerization and coated with the above inorganic component You may use what was made to do. The inorganic component is preferably one component selected from the group consisting of alumina, titania, and zirconia.
The synthesis method of ii) is the same as the method of iii) except that the resin fine particles are synthesized by a polymerization reaction in the method of iii). Therefore, the method iii) will be specifically described below.

The resin fine particles can be obtained by pulverizing a polymerized monomer synthesized by bulk polymerization, or a polymer obtained by polymerizing a polymerizable monomer by solution polymerization and polymerizing the resulting solution. It can also be obtained by adding to a poor solvent, or it can be obtained by polymerizing a polymerizable monomer by emulsion polymerization. However, as will be described later, the number average particle size of the core-shell type composite fine particles is preferably in the range of 30 to 300 nm. Since composite fine particles in the range are easily obtained, it is preferable to obtain resin fine particles by emulsion polymerization.
For emulsion polymerization, conventionally known emulsion polymerization methods can be employed. In the emulsion polymerization, polymerization auxiliary materials such as emulsifiers, polymerization initiators, molecular weight modifiers and the like used in normal polymerization can be used.

  Examples of the resin used in the resin fine particles for coating the inorganic component such as alumina in the present invention include polymers obtained by homopolymerizing or copolymerizing the polymerizable monomers exemplified below. Examples of the polymerizable monomer include a monovinyl monomer and a crosslinkable polymerizable monomer. Monovinyl monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, and derivatives thereof; ethylene, propylene, butylene Ethylenically unsaturated monoolefins such as vinyl and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl iodide; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; Methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid-n-octyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid dimethylaminoethyl, (meth) (Meth) acrylic acid such as diethylaminoethyl acrylate Ester ethers, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether; acrylonitrile, methacrylonitrile, can be mentioned acrylic acid derivatives such as acrylamide.

  Examples of the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; carboxylic acids having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate. An ester compound in which two or more acids are ester-bonded; Other divinyl compounds such as N, N-divinylaniline and divinyl ether;

These monomers can be used alone or in combination of two or more. Among these, it is preferable to use a combination of a monovinyl monomer and a crosslinkable polymerizable monomer. By combining these, crosslinked resin fine particles can be obtained. Among the monovinyl monomers, styrene and its derivatives and (meth) acrylic acid esters are more preferable, styrene and its derivatives are more preferable, and styrene is particularly preferable. As the crosslinkable polymerizable monomer, an aromatic divinyl compound and an ester compound in which two or more (meth) acrylic acids are ester-bonded to an alcohol having two or more hydroxyl groups are more preferable, and an aromatic divinyl compound is more preferable. Divinylbenzene is particularly preferred.
The ratio of the monovinyl monomer and the crosslinkable monomer that is preferably used is such that the ratio of the crosslinkable monomer is 0.1 to 20% by mass of the total monomers, and 0.3 to 10%. It is more preferable that it is mass%, and it is still more preferable that it is 0.5-5 mass%.

The emulsifier used in the emulsion polymerization of latex is not limited to a specific emulsifier. Specific examples of the emulsifier include anionic emulsifiers such as alkyl benzene sulfonates, aliphatic sulfonates, sulfate esters of higher alcohols; polyethylene glycol alkyl ether type, polyethylene glycol alkyl ester type, polyethylene glycol alkyl phenyl ether type, etc. Nonionic emulsifier; amphoteric surfactant having carboxylate, sulfate ester, sulfonate, phosphate, phosphate ester salt, etc. as anion moiety, and amine salt, quaternary ammonium salt, etc. as cation moiety And so on.
The usage-amount of an emulsifier is 0.05-5 mass parts normally with respect to 100 mass parts of monomer whole quantity used for emulsion polymerization, Preferably it is 0.05-2 mass parts.

  The polymerization initiator used in latex emulsion polymerization is not limited to a specific polymerization initiator. Specific examples of the polymerization initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-menthane hydro Peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t- Organic peroxides such as butyl peroxyisobutyrate; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate. A preferred polymerization initiator is an inorganic peroxide. These polymerization initiators can be used alone or in combination of two or more. Redox polymerization initiators in which these polymerization initiators are combined with a reducing agent such as sodium sulfite can also be used.

  The usage-amount of a polymerization initiator is 0.1-5 mass parts normally with respect to 100 mass parts of monomer whole quantity used for emulsion polymerization, Preferably it is 0.5-3 mass parts. When emulsion polymerization is performed in multiple stages, even if the total amount of polymerization initiator to be used is added in the first stage, a part of the polymerization initiator to be used is added in the first stage, and the remainder is added in the second and subsequent stages. May be. The addition method of the polymerization initiator in each stage may be batch addition, continuous addition, or divided addition.

At the time of emulsion polymerization of latex, auxiliary materials such as a molecular weight regulator, a dispersant, a chelating agent and the like that are usually used in emulsion polymerization can be added. The type and amount of the secondary material are not limited. When the emulsion polymerization is performed in a plurality of stages, the addition timing and addition method of the auxiliary material to be used are not limited as necessary.
Specific examples of the molecular weight modifier include: α-methylstyrene dimer; mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, methylene bromide; tetraethylthiuram Sulfur-containing compounds such as disulfide, dipentamethylene thiuram disulfide and diisopropylxanthogen disulfide. These molecular weight modifiers can be used alone or in combination of two or more.

  The polymerization temperature during latex emulsion polymerization is not limited to a specific range. The said polymerization temperature is 5-95 degreeC normally, Preferably it is 50-95 degreeC. When emulsion polymerization is performed in a plurality of stages, the polymerization temperature at each stage may be different, or the polymerization temperature during the emulsion polymerization at each stage may be changed.

  The number average particle diameter of the resin fine particles is preferably 10 to 300 nm, and more preferably 20 to 200 nm. This is because the number average particle diameter of the composite fine particles described later is preferably 30 to 300 nm.

As a suitable method for covering the resin fine particles in the present invention with a continuous layer of an inorganic component such as alumina, a coating technique using a sol-gel method may be used. Hereinafter, the titania coating by the sol-gel method will be described as an example.
After dispersing fine resin particles as a base in water and / or an aqueous medium in which titanium alkoxide is dissolved, the dispersion is dropped into water and / or an aqueous medium to which alkali is added, or Or the water and / or aqueous medium which added the alkali are dripped in the said dispersion solution. According to this method, the titanium alkoxide dissolved in the dispersion containing the resin fine particles undergoes hydrolysis and polycondensation in the presence of alkali and gradually insolubilizes. It is deposited on the surface of the resin fine particles due to the interaction. As a result, a coating layer is formed on the surface of the resin fine particles by adhering the granular mass containing titania to each other. In this method, in order to selectively coat the titania granular mass on the surface of the resin fine particles, the resin fine particles as a base material are dispersed in water and / or an aqueous medium in which titanium alkoxide is dissolved, and then stirred. If necessary, it is preferable to disperse resin fine particles in a medium in which titanium alkoxide is dissolved by applying heat.

  Examples of the titanium alkoxide used above include the following. Examples of the bifunctional or higher functional titanium alkoxide include tetramethoxy titanium, tetraethoxy titanium, tetra n-propoxy titanium, tetra i-propoxy titanium, tetra n-butoxy titanium, tetra i-butoxy titanium, tetra s-butoxy. Titanium, tetra-t-butoxy titanium, tetra-n-pentoxy titanium, tetra-n-hexyloxy titanium and the like can be mentioned.

  In the present invention, resin fine particles can be suitably covered with a continuous layer of alumina by alumina coating by a sol-gel method. Examples of the aluminum alkoxide that can be used in the sol-gel method include the following. Examples of the bifunctional or higher functional aluminum alkoxide include, for example, trimethoxyaluminum, triethoxyaluminum, tri-n-propoxyaluminum, tri-i-propoxyaluminum, tri-n-butoxyaluminum, tri-i-butoxyaluminum, tris-butoxyaluminum. , Tri-t-butoxyaluminum, tri-n-pentoxyaluminum, tri-n-hexyloxyaluminum and the like.

  In the present invention, the resin fine particles can be suitably covered with a continuous layer of zirconia by zirconia coating by a sol-gel method. Examples of zirconium alkoxide that can be used in the sol-gel method include the following. Examples of the bifunctional or higher functional zirconium alkoxide include tetramethoxy zirconium, tetraethoxy zirconium, tetra n-propoxy zirconium, tetra n-butoxy zirconium, and the like.

  Alumina, titania, and zirconia may each be coated with resin fine particles, or a mixture of two or more inorganic components may be coated with resin fine particles.

  As the aqueous medium used in the sol-gel reaction, for example, alcohols such as methanol, ethanol, and isopropanol are used. When the organic nature of these solvents increases, the solubility of the polycondensate of the alkoxide that is an inorganic component increases, and the resin The polycondensate becomes difficult to deposit on the surface of the fine particles. Therefore, it is preferable to use methanol or ethanol as the aqueous medium.

In addition, it is preferable that the surface of the core-shell type composite fine particles is subjected to a hydrophobization treatment so that the core-shell type composite fine particles prepared by the above method have a stable effect even under high temperature and high humidity. As the hydrophobic treatment agent, either a positively chargeable treatment agent or a negatively chargeable treatment agent can be used. As the hydrophobizing agent, for example, a silane coupling agent, silicone oil, or the like can be used.
Examples of the silane coupling agent include disilazane such as hexamethyldisilazane; cyclic silazane; trimethylsilane; trimethylchlorosilane; dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, and methyltrimethoxysilane. , Methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-octadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxy Alkylsilane compounds such as silane, γ-methacryloxypropyltrimethoxysilane, and vinyltriacetoxysilane, and γ- Aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N- (2 -Aminoethyl) 3-aminopropyltrimethoxysilane, and aminosilane compounds such as N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane; These can be used alone or in combination of two or more.
Examples of the silicone oil include dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, and amino-modified silicone oil. These can be used alone or in combination of two or more.
Among the above, the hydrophobizing agent may be contained alone or in combination of two or more, and when a silane coupling agent or silicone oil is used, the resulting toner is more preferable because it provides high image quality. .

As a method of hydrophobizing the core-shell type composite fine particles used as an external additive in the present invention, a general method can be used, and examples thereof include a wet method and a dry method.
Specifically, the dry method represented by the method of dripping or spraying the hydrophobic treatment agent while stirring the core-shell composite fine particles used as an external additive at high speed, and dissolving the hydrophobic treatment agent in an organic solvent In addition, a wet method represented by a method of adding core-shell type composite fine particles while stirring an organic solvent containing a hydrophobizing agent may be used. The wet method is preferable because the core-shell composite fine particles can be uniformly hydrophobized.

When the wet method is used, the reaction liquid obtained by adding an organic solvent containing a hydrophobizing agent is used as it is while stirring the reaction liquid of the core-shell composite fine particles obtained by the sol-gel reaction. Hydrophobic treatment can be performed by adding a reaction solution of core-shell type composite fine particles obtained by sol-gel reaction while stirring an organic solvent containing a hydrophobization treatment agent. You can also.
However, in the wet method, the core-shell type composite fine particles obtained by the sol-gel reaction are washed, filtered, and dried, and then the core-shell type composite fine particles are dispersed in an organic solvent and the hydrophobization treatment agent is contacted. Is preferred. Hydrophobized core-shell composite fine particles dispersed in an organic solvent, obtained by this preferred method, are used after removing the organic solvent by distillation under reduced pressure, drying and crushing as necessary.

4). Core-shell type composite fine particles Core-shell type composite fine particles are obtained by the above-described production method. Hereinafter, the core-shell type composite fine particles used as the external additive of the present invention will be described.

The core-shell type composite fine particles used as an external additive in the present invention are core-shell type composite fine particles in which the surface of the resin fine particles is coated with an inorganic component.
In this invention, it is preferable that the volume ratio of the inorganic component of the said composite fine particle is 25-75 volume% when the total volume of a core-shell type composite fine particle is 100 volume%.
When the volume ratio is less than 25% by volume, the amount of metal oxide decreases, and thus there is a possibility that the effect of suppressing the increase in charge in a low-temperature, low-humidity (L / L) environment may not be exhibited. On the other hand, when the volume ratio exceeds 75% by volume, since the amount of metal oxide is large, charging tends to be reduced in a high-temperature and high-humidity (H / H) environment, and fog may be deteriorated.
When the total volume of the core-shell composite fine particles is 100% by volume, the volume ratio of the inorganic component of the composite fine particles is more preferably 30 to 70% by volume, and still more preferably 50 to 70% by volume.

  In the present invention, the volume ratio of the inorganic component of the core-shell composite fine particles is the ratio of the volume of the coated alumina, titania and / or zirconia to the total volume of the core-shell composite fine particles. The ratio is the ratio of the increase in the volume of the resin fine particles as the raw material to the volume of the core-shell composite fine particles with respect to the total volume of the core-shell composite fine particles, and the number average particle diameter of the resin fine particles and the core-shell composite fine particles It can be calculated from the number average particle diameter of

When it is unknown whether the fine particles are core-shell type composite fine particles, when calculating the volume ratio of the inorganic component of the fine particles, for example, the following method can be employed.
First, using atomic absorption spectrometry or the like, it is confirmed whether or not the fine particles contain alumina, titania and / or zirconia.
When the fine particles are found to contain alumina, titania and / or zirconia, the number average particle diameter of the fine particles is measured in the same manner as described above. Subsequently, the fine particles are put into hydrofluoric acid to dissolve alumina, titania and / or zirconia, washed with water and then dried, and the number average particle diameter of the resin fine particles as the core is the same as above. Measure. From the two values of the number average particle diameter before and after dissolution of the inorganic component measured in this manner, the volume ratio of the inorganic component of the fine particles can be calculated.

The amount of adsorbed moisture of the core-shell type composite fine particles is preferably 0.5 to 2.5% by mass. When the amount of adsorbed moisture is less than 0.5% by mass or when the amount of adsorbed moisture exceeds 2.5% by mass, the environmental stability of the toner described later deteriorates and the high-temperature and high-humidity of the toner deteriorates. There is a risk of fogging in the environment.
The adsorbed moisture content of the core-shell composite fine particles is more preferably 0.5 to 2.0% by mass, and still more preferably 0.8 to 1.5% by mass.
In the present invention, the amount of adsorbed moisture is determined by allowing the sample to stand in a dry nitrogen stream for 1 hour using a moisture absorption / desorption measuring device (IGAsorb, manufactured by Nippon Siebel Hegner), and then in air at 32 ° C. and 80% humidity. Then, moisture was adsorbed for 1 hour, and the mass of the sample adsorbed with moisture was measured. From the measurement results, (increased mass / sample mass) × 100 was defined as the amount of adsorbed moisture (mass%).

It is preferable that the core-shell type composite fine particles exhibit positive chargeability. When the negatively chargeable core-shell type composite fine particles are used, there is a possibility that the charge amount of the toner is lowered and fogging is likely to occur.
The absolute value of the blow-off charge amount of the core-shell type composite fine particles is preferably 200 to 2000 μC / g. When the value is less than 200 μC / g, the charge amount of the toner may be reduced and fog may be easily generated. On the other hand, when the value exceeds 2000 μC / g, it is difficult to prepare the core-shell composite fine particles.
The absolute value of the blow-off charge amount of the core-shell type composite fine particles is more preferably 300 to 1500 μC / g, and still more preferably 400 to 1200 μC / g.

The number average particle diameter of the core-shell type composite fine particles is preferably 30 to 300 nm. When the number average particle diameter is less than 30 nm, the charge amount of the toner may be reduced and fog may be easily generated. On the other hand, when the number average particle diameter exceeds 300 nm, the environmental stability of the toner described later may be deteriorated, and the fogging of the toner in a high temperature and high humidity environment may be deteriorated.
The number average particle size of the core-shell type composite fine particles is more preferably 40 to 250 nm, and further preferably 50 to 200 nm.

5. Production method of toner of the present invention The toner of the present invention is prepared by mixing and stirring the colored resin particles together with the core-shell composite fine particles, and suitably attaching and externally adding the core-shell composite fine particles to the surface of the colored resin particles. Can be obtained.

The addition amount of the core-shell type composite fine particles is preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles. When the addition amount of the core-shell type composite fine particles is less than 0.1 parts by mass with respect to 100 parts by mass of the colored resin particles, the effect of the present invention is not sufficiently exhibited. On the other hand, when the addition amount of the core-shell type composite fine particles exceeds 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles, the charge amount of the toner may be lowered.
The addition amount of the core-shell type composite fine particles is preferably 0.15 to 1.0 part by mass, more preferably 0.2 to 0.8 part by mass with respect to 100 parts by mass of the colored resin particles.

  The method for adhering and adding (external addition) the core-shell type composite fine particles to the surface of the colored resin particles is not particularly limited. , Kawada Seisakusho Co., Ltd.), Q mixer (: trade name, manufactured by Mitsui Mining Co., Ltd.), Mechano Fusion System (: trade name, manufactured by Hosokawa Micron Corporation), and Mechano Mill (: trade name, manufactured by Okada Seiko Co., Ltd.) Can be performed using an apparatus capable of.

Other external additives may be mixed with the core-shell type composite fine particles.
Examples of the other external additives include inorganic fine particles made of silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and / or cerium oxide; polymethyl methacrylate resin, silicone resin, and And / or organic fine particles comprising melamine resin and the like. Among these, inorganic fine particles are preferable, and among inorganic fine particles, silica and / or titanium oxide are preferable, and fine particles made of silica are particularly preferable.
In addition, the said other external additive used together with a core-shell type composite microparticle may be only one type, and may be two or more types.
0.1-6 mass parts is preferable, as for the addition amount of another external additive, 0.3-5 weight part is more preferable, 0.5-4 weight part is still more preferable.

When the core-shell type composite fine particles are used in combination with another external additive, the number average particle diameter of the other external additive is preferably 7 to 300 nm. When the number average particle diameter of the other external additive is less than 7 nm, the other external additive is easily embedded from the surface of the colored resin particles to the inside, and the fluidity is sufficiently sufficient for the toner particles. In some cases, it cannot be applied, and the printing performance may be adversely affected. On the other hand, when the number average particle diameter of the other external additive exceeds 300 nm, the ratio (coverage) of the other external additive to the surface of the toner particles decreases, so that the fluidity May not be sufficiently imparted to the toner particles, which may adversely affect printing performance.
The number average particle diameter of the other external additive is more preferably 15 to 80 nm.

6). Toner of the present invention The toner of the present invention obtained through the above-described steps is obtained by using core-shell type composite particles in which the surface of resin particles is coated with alumina, titania and / or zirconia as an external additive. The increase in toner charge amount under the environment is suppressed, stable printing can be performed without impairing fine line reproducibility under the same environment, and there are no printing defects caused by the increase in charge amount, resulting in good image quality. This is a toner for developing an electrostatic image.

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

1. Production of core-shell composite fine particles [Production Example 1]
In a container equipped with a stirrer substituted with nitrogen, 3 parts of soft dodecylbenzenesulfonic acid was dissolved in 150 parts of ion-exchanged water, and then 95 parts of styrene was emulsified to prepare a polymerizable monomer emulsion. After raising the temperature of the emulsion to 80 ° C., 0.6 part of potassium persulfate dissolved in 10 parts of ion exchange water was added and polymerized for 2 hours. Subsequently, after the reactor temperature was lowered to 40 ° C., 5 parts of divinylbenzene was added and stirred for 2 hours, and then the temperature was raised to 85 ° C. and potassium persulfate dissolved in 2 parts of water 0.1 The polymerization reaction was carried out for 4 hours by adding a portion, and an aqueous hydroquinone solution was added as a reaction terminator to complete the polymerization. The polymerization conversion rate at this time was 99%. Water soluble material was removed by ultrafiltration. By adjusting the pH and concentration of the emulsion, a resin fine particle emulsion having a solid content concentration of 50% and a pH of 8.5 was obtained. A part of this emulsion was dried and subjected to measurement of the number average particle diameter of resin fine particles described later. The number average particle diameter of the resin fine particles was 80 nm.

After adding 200 parts (100 parts of solid content conversion) of the obtained emulsion to 10,000 parts of methanol, 750 parts of tetraethoxytitanium was dissolved as a titanium compound. In this state, the mixture was heated to 50 ° C. and stirred for 1 hour to disperse the resin fine particles in a medium in which titanium alkoxide was dissolved. Next, 20 parts of a 28% by mass NH ₄ OH aqueous solution was added dropwise to this solution, and the mixture was stirred at room temperature for 48 hours to carry out a sol-gel reaction, thereby coating the surface of the resin fine particles with titania.

  After completion of the reaction, the obtained fine particles were washed with ion-exchanged water, then washed with methanol, the fine particles were filtered off, and then dried at 45 ° C. for 24 hours under a reduced pressure of 40 kPa. Core-shell composite fine particles 1 coated with titania were obtained. A part of the core-shell type composite fine particles 1 was subjected to measurement of the number average particle size of the core-shell type composite fine particles described later.

  100 g of the core-shell type composite fine particles 1 are dispersed in 600 g of toluene, and 1 part of 3-aminopropyltriethoxysilane (a silicon compound containing an amino group) is added to 100 parts of the fine particles 1, and then dispersed and mixed for 15 minutes. And contacted with the fine particles. Next, 1 part of hexamethyldisilazane (a silicon compound containing no amino group) was added to the fine particles, and then dispersed and mixed for 15 minutes to contact the fine particles. The dispersion was distilled under reduced pressure and dried, and then the fine particles were crushed to obtain core-shell type composite fine particles A that were hydrophobized to be positively charged. There was no change in particle size due to the hydrophobization treatment.

[Production Example 2]
In the production example 1, the amount of soft dodecylbenzenesulfonic acid added was changed from 3 parts to 8 parts, and as a result of polymerization, a resin particle emulsion having a number average particle diameter of 50 nm was obtained, and the core-shell type composite fine particles were Core-shell composite fine particles B were produced in the same manner as in Production Example 1 except that the amount of tetraethoxy titanium added was changed from 750 parts to 900 parts at the time of production.

[Production Example 3]
Core-shell composite fine particles C were produced in the same manner as in Production Example 1 except that the sol-gel reaction time was changed from 48 hours to 72 hours in Production Example 1.

[Production Example 4]
In the above Production Example 1, the polymerizable monomer used in the first polymerization was changed from 95 parts of styrene and 5 parts of divinylbenzene to 100 parts of styrene, except that 5 parts of divinylbenzene added later was not used. Core-shell composite fine particles D were produced in the same manner as in Production Example 1 above.

[Production Example 5]
In production example 1, core-shell composite fine particles E were produced in the same manner as in production example 1 except that 750 parts of tetraethoxytitanium were changed to 750 parts of triethoxyaluminum when producing the core-shell composite fine particles.

[Production Example 6]
In the production example 1, as a result of polymerization by changing the addition amount of soft-type dodecylbenzenesulfonic acid from 3 parts to 0.8 parts, a resin particle emulsion having a number average particle size of 150 nm was obtained, and the core-shell type composite Core-shell composite fine particles F were produced in the same manner as in Production Example 1 except that 750 parts of tetraethoxytitanium were changed to 620 parts of triethoxyaluminum when producing the fine particles.

2. Evaluation of physical properties of composite fine particles The core-shell composite fine particles A to F obtained from the above Production Examples 1 to 6 were measured for number average particle diameter and adsorbed water content. In addition, the number average particle diameter of the resin fine particles as the raw material of the core-shell type composite fine particles A to F was also measured, and the ratio of the inorganic components of the core-shell type fine composite particles was calculated.

2-1. Measurement of the number average particle size of the core-shell type composite fine particles and the resin fine particles as the raw material The number average particle size of the core shell type composite fine particles and the fine resin particles as the raw material were measured by the following method. That is, these fine particles were observed using a field emission scanning electron microscope (manufactured by Hitachi, Ltd., model S-4500). The particle diameter was measured so that the cumulative number was 300 or more, and the number average particle diameter was calculated.

2-2. Calculation of ratio of inorganic component of core-shell type composite fine particles For core-shell type composite fine particles A to F, the ratio of the volume of the coated inorganic component to the total volume of the core-shell type composite fine particles was calculated based on the following formula.
[Ratio of the inorganic component] = [{(4/3) π (r 2/2) 3 - (4/3) π (r 1/2) 3} / {(4/3) π (r 2/2 ) ³ }] × 100 = {(r ₂ ³ −r ₁ ³ ) / (r ₂ ³ )} × 100
(In the above formula, r ₁ is the number average particle diameter of the resin fine particles as the core, and r ₂ is the number average particle diameter of the core-shell composite fine particles.)

2-3. Measurement of Adsorbed Moisture Content of Core-Shell Type Composite Fine Particles A moisture absorption / desorption measuring device (IGAsorp, manufactured by Sybel Hegner, Japan) was used for measuring the adsorbed water content. The sample was left in the apparatus in a dry nitrogen stream for 1 hour, and then moisture was adsorbed in air at 32 ° C. and 80% humidity for 1 hour, and the mass of the sample adsorbed with moisture was measured. From the measurement results, (increased mass / sample mass) × 100 was defined as the amount of adsorbed moisture (mass%).

  For the core-shell type composite fine particles A to F, the measurement result of the adsorbed water content is shown in Table 1 together with the structure data of each particle.

3. 3. Production of colored resin particles and evaluation of physical properties 3-1. Preparation of polymerizable monomer composition for core 83 parts of styrene and 17 parts of n-butyl acrylate as monovinyl monomer (calculation of the resulting copolymer Tg = 60 ° C.), carbon black as a black colorant (Mitsubishi Chemical Corporation) Manufactured, trade name: # 25B) 7 parts, positive charge control resin (manufactured by Fujikura Kasei Co., Ltd., trade name: FCA-207P, styrene / acrylic resin) as charge control agent, 1 part of crosslinkable polymerizable monomer 0.6 parts of divinylbenzene as a body, 1.9 parts of t-dodecyl mercaptan as a molecular weight regulator, and polymethacrylate macromonomer (manufactured by Toa Gosei Co., Ltd., trade name: AA6, Tg of the resulting polymer) After stirring and mixing with a stirrer, 0.25 part (94 ° C.) was further uniformly dispersed using a media-type disperser. Here, 5 parts of dipentaerythritol hexamyristate was added, mixed and dissolved as a release agent to obtain a polymerizable monomer composition.

3-2. Preparation of Aqueous Dispersion Medium On the other hand, at room temperature, in an aqueous solution in which 10.2 parts of magnesium chloride (water-soluble polyvalent metal salt) is dissolved in 250 parts of ion-exchanged water, sodium hydroxide (alkali hydroxide) is added to 50 parts of ion-exchanged water. An aqueous solution in which 6.2 parts of the metal was dissolved was gradually added under stirring to prepare a magnesium hydroxide colloid (slightly water-soluble metal hydroxide colloid) dispersion.

3-3. Granulation step The polymerizable monomer composition was charged into the magnesium hydroxide colloid dispersion at room temperature and stirred. After adding 6 parts of t-butyl peroxy-2-ethylhexanoate (Nippon Yushi Co., Ltd., trade name: Perbutyl O) as a polymerization initiator, an in-line type emulsifier / disperser (trade name, manufactured by Ebara Corporation) is added. : Ebara Milder) was dispersed by high-speed shearing and stirring at a rotational speed of 15,000 rpm for 10 minutes to form droplets of the polymerizable monomer composition.

3-4. Suspension polymerization step A suspension (polymerizable monomer composition dispersion) in which droplets of the above polymerizable monomer composition are dispersed is charged into a reactor equipped with a stirring blade and heated to 90 ° C. Warm to initiate the polymerization reaction. When the polymerization conversion reached almost 100%, 2,2′-azobis (shell polymerization initiator dissolved in 1 part of methyl methacrylate and 10 parts of ion-exchanged water as shell polymerizable monomer) 0.3 part of 2-methyl-N- (2-hydroxyethyl) -propionamide) (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086, water-soluble) was added, and the reaction was continued at 90 ° C. for 4 hours. Thereafter, the reaction was stopped by cooling with water to obtain an aqueous dispersion of colored resin particles having a core-shell structure.

3-5. Post-treatment step The aqueous dispersion of the colored resin particles was added dropwise with stirring sulfuric acid at room temperature, and acid washing was performed until the pH was 6.5 or less. Subsequently, filtration separation was performed, 500 parts of ion-exchanged water was added to the obtained solid content to make a slurry again, and water washing treatment (washing, filtration, dehydration) was repeated several times. Next, filtration separation was performed, and the obtained solid content was put in a container of a dryer and dried at 45 ° C. for 48 hours to obtain dried colored resin particles.

The obtained colored resin particles were measured for volume average particle diameter (Dv) and particle diameter distribution (Dv / Dn).
About 0.1 g of a measurement sample (colored resin particles) was weighed and taken in a beaker, and 0.1 mL of an alkylbenzenesulfonic acid aqueous solution (trade name: Drywell, manufactured by Fuji Film Co., Ltd.) was added as a dispersant. Add 10-30 mL of Isoton II to the beaker and disperse with a 20 W ultrasonic disperser for 3 minutes. Then, use a particle size analyzer (trade name: Multisizer, manufactured by Beckman Coulter, Inc.) to determine the aperture diameter. Measuring the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the colored resin particles under the condition of 100 μm, the number of measured particles; 100,000, and calculating the particle diameter distribution (Dv / Dn) did. As a result, the obtained colored resin particles had a volume average particle diameter (Dv) of 9.7 μm and a particle diameter distribution (Dv / Dn) of 1.14.

The average circularity of the obtained colored resin particles was calculated.
First, 10 mL of ion-exchanged water is put in a container in advance, and 0.2 mL of an alkylbenzene sulfonic acid aqueous solution (manufactured by Fujifilm, trade name: Drywell) is added as a dispersant therein, and 0.2 g of colored resin particles are further added. In addition, 60 W (Watt) was applied for 3 minutes with an ultrasonic disperser. The concentration of the colored resin particles at the time of measurement is adjusted to 3,000 to 10,000 particles / μL, and 1,000 to 10,000 colored resin particles having an equivalent circle diameter of 0.4 μm or more are flow-type particle images. Measurement was performed using an analyzer (trade name: FPIA-2100, manufactured by Simex Corporation). When the average circularity was determined from the measured value, the average circularity of the obtained colored resin particles was 0.987.

4). Manufacture of toner for developing electrostatic image The core-shell type composite fine particles explained in the above section “1. Production of core-shell type composite fine particles” and the coloration explained in the above-mentioned section “3. Production and evaluation of physical properties of colored resin particles” A toner for developing an electrostatic charge image was produced using the resin particles.

[Example 1]
To 100 parts of the colored resin particles, 0.5 part of the core-shell type composite fine particles A produced in Production Example 1 above, 0.8 part of TG-7120 (manufactured by Cabot Corporation), and NA50Y (manufactured by Nippon Aerosil Co., Ltd.) 0 parts were added, and the mixture was stirred using an FM mixer (trade name: FM-10, manufactured by Nippon Coke Co., Ltd.) and subjected to external addition treatment, whereby the electrostatic charge image developing toner of Example 1 was obtained. The peripheral speed of the stirring blade at this time was 40 m / s, and the stirring time was 5 minutes.

[Example 2]
The electrostatic charge image developing toner of Example 2 in the same manner as in Example 1 except that the core-shell type composite fine particles A produced in Production Example 1 were changed to the core-shell type composite fine particles B produced in Production Example 2 above. Got.

[Example 3]
The electrostatic charge image developing toner of Example 3 in the same manner as in Example 1 except that the core-shell type composite fine particles A produced in Production Example 1 were changed to the core-shell type composite fine particles C produced in Production Example 3 above. Got.

[Example 4]
The electrostatic charge image developing toner of Example 4 in the same manner as in Example 1 except that the core-shell type composite fine particles A produced in Production Example 1 were changed to the core-shell type composite fine particles D produced in Production Example 4 above. Got.

[Example 5]
The electrostatic charge image developing toner of Example 5 in the same manner as in Example 1 except that the core-shell type composite fine particles A produced in Production Example 1 were changed to the core-shell type composite fine particles E produced in Production Example 5 above. Got.

[Example 6]
The electrostatic charge image developing toner of Example 6 in the same manner as in Example 1 except that the core-shell type composite fine particles A produced in Production Example 1 were changed to the core-shell type composite fine particles F produced in Production Example 6 above. Got.

[Comparative Example 1]
A toner for developing an electrostatic charge image of Comparative Example 1 was obtained in the same manner as in Example 1 except that the core-shell type composite fine particles A produced in Production Example 1 were not used.

5. Evaluation of Toner for Developing Electrostatic Image The toner for developing an electrostatic image of Examples 1 to 6 and Comparative Example 1 is fogged in a normal temperature and normal humidity (N / N) environment or a high temperature and high humidity (H / H) environment. Tests, evaluation of fine line reproducibility in a low temperature and low humidity (L / L) environment, and a printing durability test in a normal temperature and normal humidity (N / N) environment were performed.

5-1. A fog test under a normal temperature and normal humidity (N / N) environment A commercially available non-magnetic one-component developing type printer (HL-3040CN) was used for the test. After the toner cartridge of the developing device was filled with toner, the toner cartridge was left in a normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%) for 24 hours. After leaving it to stand, in the same environment, perform one white print, measure the whiteness of the white print on the paper surface using a whiteness meter (manufactured by Nippon Denshoku), and calculate the fog density using the following formula. did.
(Whiteness before printing)-(Whiteness of white printed matter) = (Fog density)

5-2. Fog test under high-temperature and high-humidity (H / H) environment After the toner cartridge of the developing device is filled with toner, it is kept under a high-temperature and high-humidity (H / H) environment (temperature: 35 ° C., humidity: 80%) for 24 hours. The fog density was calculated in the same manner as in the fog test under a normal temperature and normal humidity (N / N) environment, except that the fog was measured under the environment after being allowed to stand.

5-3. Evaluation of fine line reproducibility After leaving the toner in a low-temperature and low-humidity (L / L) environment (temperature 10 ° C., humidity 20% RH) for 1 day, the printer (HL-3040CN) used in the fog test 2 A line image was continuously formed with x2 dot lines (width of about 85 μm), and printing was performed up to 10,000 sheets.
For every 500 prints, the measurement was performed by a print evaluation system (trade name “RT2000” manufactured by YA-MA), and the density distribution data of the line image was collected.
The line width of a thin line image in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%) is used as a criterion for evaluation. As an evaluation method, the full width at half maximum of the maximum concentration in a low temperature and low humidity (L / L) environment is defined as the line width, and the difference between the line width and the reference line width is 10 μm or less is one sheet. Evaluated as ◎ for reproducing the line image of the eye. A case where the difference in the line width can be maintained at 10 μm or more and 20 μm or less is evaluated as ◯. Those exceeding 20 μm are evaluated as x.

5-4. Print durability test under normal temperature and normal humidity (N / N) environment For the print durability test, a commercially available non-magnetic one-component development type printer (HL-3040CN) is used, and the toner cartridge of the developing device is filled with toner. After that, the printing paper was set.
After standing for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), continuous printing was performed up to 10,000 sheets at a 5% print density in the same environment. . Black solid printing (printing density 100%) was performed every 500 sheets, and the printing density of the black solid image was measured using a reflective image densitometer (trade name: RD918, manufactured by Macbeth). After that, white solid printing (printing density 0%) is performed, the printer is stopped in the middle of white solid printing, and the toner in the non-image area on the developed photosensitive member is adhesive tape (manufactured by Sumitomo 3M Ltd., product) Name: Scotch mending tape 810-3-18), and then peeled off and affixed to printing paper. Next, the whiteness (B) of the printing paper on which the adhesive tape is affixed is measured with a whiteness meter (trade name: ND-1 manufactured by Nippon Denshoku Co., Ltd.). The whiteness (A) was measured and the difference in whiteness (B−A) was defined as the fog value (%). Smaller values indicate better fog and better.
The number of continuously printed sheets that can maintain an image quality with a print density of 1.3% or more and a fog value of 3% or less was examined.
In Table 1, “10000 <” indicates that the image quality with the print density of 1.3% or more and the fog value of 3% or less was maintained even at the time of 10,000 sheets. .

  Table 2 shows the measurement and evaluation results of the electrostatic charge image developing toners of Examples 1 to 6 and Comparative Example 1 together with the toner compositions.

6). Summary of Toner Evaluation First, the toner of Comparative Example 1 will be examined. In the toner of Comparative Example 1, the fog density in a normal temperature and normal humidity (N / N) environment is 0.7, and the fog generation number in a normal temperature and normal humidity (N / N) environment exceeds 10,000. There is no problem in printing durability under a normal temperature and normal humidity (N / N) environment.
However, the fog density in the high-temperature and high-humidity (H / H) environment of the toner of Comparative Example 1 is 3.2. This result is the highest fog density among the toners of Examples 1 to 6 and Comparative Example 1. is there. Further, in the evaluation of fine line reproducibility in a low temperature and low humidity (L / L) environment, only the toner of Comparative Example 1 was evaluated as x.
From these results, the toner of Comparative Example 1 that does not contain the core-shell type composite fine particles whose surface is coated with an inorganic component as an external additive has a printing durability and high durability under a high temperature and high humidity (H / H) environment. It turns out that it is inferior to the fine line reproducibility in a low-temperature, low-humidity (L / L) environment.

  Compared to Comparative Example 1, the toners of Examples 1 to 6 each have a fog density of 0.8 or less in a normal temperature and normal humidity (N / N) environment, and high temperature and high humidity (H / H). The fog density in the environment is 2.6 or less, the number of fog occurrences in a room temperature and normal humidity (N / N) environment exceeds 7,000, and the environment is low temperature and low humidity (L / L). The evaluation of fine line reproducibility below is ◯ or more. Therefore, the toners of Examples 1 to 6 including the core-shell type composite fine particles having the inorganic component coated on the surface of the resin fine particles as the external additive are stable without being impaired in the fine line reproducibility even in a low temperature and low humidity environment. It can be seen that printing can be performed and that there is no printing defect caused by an increase in the charge amount, and that a good image quality can be obtained.

Claims (7)

A toner for developing an electrostatic charge image, comprising colored resin particles containing a binder resin and a colorant, and an external additive,
As the external additive, the surface of the resin fine particles includes core-shell type composite fine particles in which a continuous layer of at least one inorganic component selected from the group consisting of alumina and titania is coated. Toner for image development.   2. The electrostatic charge according to claim 1, wherein the volume ratio of the inorganic component in the composite fine particles is 25 to 75 vol% when the total volume of the core-shell composite fine particles is 100% by volume. Toner for image development.   The electrostatic charge image developing toner according to claim 1, wherein the core-shell type composite fine particles have an adsorbed water content of 0.5 to 2.5 mass%.   4. The static electricity according to claim 1, wherein the addition amount of the core-shell type composite fine particles is 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles. 5. Toner for charge image development.   5. The electrostatic charge image developing toner according to claim 1, wherein the core-shell type composite fine particles have a number average particle size of 30 to 300 nm.   The static resin according to any one of claims 1 to 5, wherein the colored resin particles have a volume average particle diameter of 4 to 12 µm and an average circularity of 0.96 to 1.00. Toner for charge image development.   The electrostatic image developing toner according to claim 1, wherein the resin fine particles constituting the core-shell type composite fine particles are a crosslinked resin.