JPWO2006070871A1 - Toner for electrostatic image development - Google Patents

Abstract

In the toner for developing an electrostatic charge image containing colored particles and an external additive, the external additive contains at least two kinds of inorganic fine particles, and the inorganic fine particles (A) as the first inorganic fine particles have an average circularity of 0. 9 to 1.0, the average primary particle diameter is 80 to 300 nm, and the slope a (standardized photoelectron yield / excitation energy) of the normalized photoelectron yield of the inorganic fine particles A is 20 to 60 (1 / eV), and an electrostatic image developing toner in which the average primary particle diameter of the inorganic fine particles (B) as the second inorganic fine particles is 5 to 80 nm.

Description

  The present invention is a static image used for developing a latent image having electrostatic characteristics such as an electrostatic latent image and a magnetic latent image in electrophotography, electrostatic recording method, electrostatic printing method, magnetic recording method and the like. The toner for developing an electrostatic latent image (hereinafter, sometimes simply referred to as “toner”) will be described in more detail. In addition, the image forming apparatus has a good cleaning property and a sufficient image density, resulting in poor development. The present invention relates to a toner for developing an electrostatic charge image that does not generate a toner.

  The electrophotographic method is to develop an electrostatic latent image formed on a photoreceptor with a toner for developing an electrostatic charge image formed by blending colored particles with other particles such as an external additive and a carrier, if necessary. In this method, the toner is transferred to a recording material such as paper or an OHP sheet, and then the transferred toner is fixed to obtain a printed matter. Color image formation by full-color electrophotography is to reproduce all colors using three color toners of magenta, cyan and yellow, preferably four color toners in addition to the above three color toners. is there.

  As a full-color image forming method by full-color electrophotography, for example, light reflected from an original is subjected to analog or digital color separation, and then the separated light is guided to the photoconductive layer of the photosensitive member, and first color of the first color An electrostatic latent image is formed. Next, after the development and transfer processes, the first color toner is held on a recording material such as paper. By repeating the same operation for the second and subsequent colors, a plurality of color toners are superimposed on the same recording material. By fixing this by various methods such as heating, pressurization, and solvent vapor, a printed matter of a full color image can be obtained.

  At this time, as a cleaning process for removing the transfer residual toner remaining on the surface of the photosensitive member, there are a simultaneous development cleaning method (cleaner-less method) that does not use a cleaning device and a cleaning method that uses a cleaning device such as a cleaning blade. .

  In the cleaning using the cleaning blade, the cleaning property tends to be lowered with a toner having a small particle diameter or a spherical toner. In recent years, it has become difficult to clean the transfer residual toner on the surface of the photoreceptor due to the increase in the printing speed studied in the image forming apparatus.

  If the transfer residual toner on the photoconductor is poorly cleaned, it will be difficult to repeat the printing normally over a long period of time, such as soiling of the ground color of the printed matter and color mixing in full-color electrophotography. Sexuality gets worse.

  Therefore, it is desirable that there is no untransferred toner on the photoreceptor, and a toner with excellent cleaning properties is desired.

  In order to meet these demands, various studies have been conducted from the viewpoint of an image forming apparatus (image forming method) and toner used therein. For example, in Patent Document 1, inorganic or resin fine particles having an average particle diameter of 0.01 to 0.1 times the average particle diameter of the toner are locally attached or fixed to the particle surface of the spherical toner. It is disclosed that cleaning defects can be improved by toner for developing an electrostatic latent image.

  Patent Document 2 discloses silica-coated metal oxide particles having a core-shell structure in which the core layer is made of a metal oxide selected from the group consisting of titanium dioxide, aluminum oxide, and zinc oxide, and the shell layer is made of silica, and Further, it is disclosed that the cleaning property can be improved by using a toner for developing an electrostatic latent image comprising an external additive containing silica fine particles having a volume average particle diameter of 5 to 20 nm and colored particles.

  Patent Document 3 discloses colored particles having a specific volume average particle size and shape factor, inorganic fine particles A having a number average particle size of 5 to 70 nm and inorganic particles having a number average particle size of 80 to 800 nm as external additives. It is disclosed that the problem of poor cleaning can be solved by using a toner for developing an electrostatic latent image containing fine particles B.

  Patent Document 4 also includes silica fine particles (A) having an average primary particle diameter of 5 to 20 nm and organic fine particles or inorganic fine particles (C) having an average primary particle diameter of 0.1 to 1 μm. It is disclosed that the transfer residual toner remaining on the surface of the photosensitive member can be sufficiently removed without causing defective cleaning by using an additive added to toner particles.

Japanese Patent Laid-Open No. 4-177361 (corresponding US document US Pat. No. 5,219,694A) JP 2004-177747 A Japanese Patent Laid-Open No. 10-207113 (corresponding US document US Pat. No. 5,976,750A) JP 2002-31634 A

  However, the above prior art toners have not yet been sufficient in terms of initial print density, dot reproducibility and the like.

  In general, toner for developing an electrostatic latent image is a mixture of toner particles composed of colored particles and an external additive attached to the colored particles by stirring in an electrostatic latent image developing system, such as toner particles and a developing blade. After being triboelectrically charged between the members or between the toner particles and the carrier, the toner is supplied onto a photoreceptor having an electrostatic latent image.

  The appropriately charged toner adheres to the photoreceptor in an amount corresponding to the charge density of the electrostatic latent image, and can form a desired gradation image beautifully.

  On the other hand, if the toner charge amount or the charge amount distribution is not appropriate, the toner development amount is too small, resulting in insufficient or uneven image density, and the toner on the photoreceptor should not be developed. The toner is also developed in the portion, and as a result, a problem such as fogging that the ground color of the printed matter becomes dirty occurs.

  In particular, printing when a large amount of toner is consumed in a short time, such as high-speed mass printing or continuous solid printing, or immediately after starting operation of the electrostatic latent image developing system or supplying new toner into the electrostatic latent image developing system In the initial printing immediately after printing, the toner charging speed may not be in time for the toner consumption speed. Therefore, as described above, insufficient image density, uneven image density, uneven density, fogging due to uneven charge distribution. It is easy to cause problems such as.

  In full-color electrophotography, when the charge amount or charge amount distribution of each color toner is not appropriate, for example, color reproducibility may be poor.

  Accordingly, an object of the present invention relates to a toner for developing an electrostatic charge image that has a good cleaning property on a photoreceptor of an image forming apparatus, a sufficient image density, and does not cause a development failure.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors, as an external additive, have a first average circularity, a constant average primary particle diameter, and a constant normalized photoelectron yield gradient. The inventors have found that a toner using two or more different inorganic fine particles including at least inorganic fine particles and second inorganic fine particles having a certain average primary particle diameter can achieve the above-mentioned object.

  The present invention has been made based on the above knowledge, and in an electrostatic image developing toner containing colored particles and an external additive, the external additive contains at least two types of inorganic fine particles, and the first inorganic fine particles The inorganic fine particles (A) have an average circularity of 0.9 to 1.0, an average primary particle size of 80 to 300 nm, and a slope a () of the normalized photoelectron yield of the inorganic fine particles (A). Normalized photoelectron yield / excitation energy) is 20 to 60 (1 / eV), and the average primary particle diameter of the inorganic fine particles (B) as the second inorganic fine particles is 5 to 80 nm. Toner is provided.

  In the toner for developing an electrostatic charge image of the present invention, the normalized photoelectron yield and the excitation energy of the inorganic fine particles (A) in the range from the work function value X + 0.2 eV to the work function value X + 0.8 eV Is preferably 0.95 or more.

  In the electrostatic image developing toner of the present invention, the work function of the inorganic fine particles (A) is preferably 4.80 to 5.20 (eV).

  In the toner for developing an electrostatic charge image of the present invention, as the second inorganic fine particles (B), 0.1 to 2 silica fine particles (B1) having an average primary particle diameter of 5 to 20 nm with respect to 100 parts by weight of the colored particles. It is preferable to contain 0.2 to 3 parts by weight of silica fine particles (B2) having a weight part and an average primary particle diameter of 25 to 80 nm.

  In the toner for developing an electrostatic charge image of the present invention, the degree of liberation of the inorganic fine particles (A) from the colored particles is preferably 20% or less.

  The colored particles preferably contain a charge control resin.

  The colored particles are preferably particles having a core-shell structure.

  The present invention also provides a development step of forming a visible image on a photoreceptor with the above-described toner for developing an electrostatic image, a transfer step of transferring the visible image to a recording material to form a transfer image, and the transfer image. An image forming method comprising a fixing step of fixing.

  Since the toner for developing an electrostatic charge image of the present invention as described above has good cleaning properties and developability on the photoreceptor of the image forming apparatus, it does not cause printing defects such as fogging and scumming, and durability of printing. Excellent in properties. Furthermore, since the toner of the present invention has good charge rise characteristics, a sufficient image density can be obtained even when the toner consumption rate is large or the toner charge amount is insufficient or the charge amount distribution is uneven in the initial stage of printing. can get.

  Therefore, by developing the electrostatic latent image using the toner of the present invention, it is possible to stably form a clear and beautiful image having a sufficient printing density regardless of the printing environment and printing conditions. .

1 is a diagram illustrating a configuration example of an image forming apparatus to which an electrostatic charge image developing toner of the present invention is applied. FIG. 6 is a graph showing a general tendency of a graph in which excitation energy (eV) is taken on the horizontal axis and normalized photoelectron yield is taken on the vertical axis in the work function measurement of the toner. It is a figure which shows the structural example of the dispersion system used in order to manufacture the toner for electrostatic image development of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 5 ... Charging roll, 9 ... Transfer roll, 7 ... Light irradiation apparatus, 11 ... Recording material, 13 ... Developing roll, 15 ... Developing roller blade, 17 ... Supply roll, 18 ... Stirring blade, 19 ... Toner, 21 ... Developing device, 23 ... Case, 23a ... Toner tank, 25 ... Cleaning blade, 27 ... Fixing device, 27a ... Heat roll, 27b ... Support roll, 101 ... Media type disperser, 102 ... Case, 103 ... Liquid supply port, 104 ... Liquid discharge port, 105 ... Holding tank, 106 ... Stirring motor, 107 ... Stirring blade, 108 ... Jacket, 109 ... Temperature control medium inlet, 110 ... Temperature control medium outlet, 111 ... Valve, 112 ... Line 113 ... circulation pump, 114 ... line, 115 ... line, 116 ... rotor, 117 ... media particles, 118 ... medium And breakfasts dispersing screen, 119 ... driving shaft, 120 ... cooling medium inlet, 121 ... cooling medium outlet, 122 ... jacket, 123 ... medium particle discharge slit, 124 ... cylindrical portion of the rotor, 125 ... delivery channel

  Hereinafter, the electrostatic image developing toner of the present invention will be described in detail.

  The electrostatic image developing toner of the present invention is an electrostatic image developing toner containing colored particles and an external additive, and the external additive contains at least two kinds of inorganic fine particles, and is the first inorganic fine particle. The inorganic fine particles (A) have an average circularity of 0.9 to 1.0, an average primary particle diameter of 80 to 300 nm, and a slope a (standardized photoelectron yield) of the normalized photoelectron yield of the inorganic fine particles A. (Rate / excitation energy) is 20 to 60 (1 / eV), and the average primary particle diameter of the inorganic fine particles (B) as the second inorganic fine particles is 5 to 80 nm.

  The toner of the present invention combines the above-mentioned two kinds of specific inorganic fine particles as external additives with colored particles, so that the cleaning property and developability on the photoreceptor of the image forming apparatus are good, and fog and Printing defects such as smudges do not occur and charging rise is good, so even if the toner consumption rate is high or the toner charge amount is insufficient or the charge amount distribution is uneven even at the beginning of printing. Sufficient image density can be obtained.

  The colored particles used in the present invention include a colorant and a binder resin as essential components, and may contain other components such as a charge control agent and a release agent as necessary.

As the colorant, all pigments and dyes can be used in addition to carbon black, titanium black, magnetic powder (magnetic material), oil black, and titanium white.
When obtaining a black toner, it is preferable to use carbon black, and those having a primary particle diameter of 20 to 40 nm are suitably used. When the particle size is within this range, carbon black can be uniformly dispersed in the toner and fogging is reduced, which is preferable.

  When obtaining a full color toner, a yellow colorant, a magenta colorant and a cyan colorant are usually used.

  As the yellow colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment yellow 3, 12, 13, 14, 15, 17, 62, 65, 73, 74, 75, 83, 90, 93, 97, 120, 138, 155, 180, 181, 185 and 186.

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

  As the cyan colorant, phthalocyanine compounds such as copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, and 60.

  The amount of the colorant is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

Magnetic materials include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; iron, cobalt, nickel or these and aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, Examples thereof include alloys with bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof.
The magnetic material is usually used in an amount of 10 to 60 parts by weight, preferably 20 to 50 parts by weight with respect to 100 parts by weight of the binder resin.

  As the binder resin contained in the colored particles, resins conventionally used as a binder resin for toner can be used. For example, styrene such as polystyrene and polyvinyltoluene, and polymers of substituted products thereof; styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylic acid 2 -Styrene copolymers such as ethylhexyl copolymer, styrene-methyl methacrylate copolymer, styrene ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, and styrene-butadiene copolymer; polymethyl methacrylate, Examples include hydrogenated products of polyester, epoxy resin, polyvinyl butyral, aliphatic or alicyclic hydrocarbon resin, polyolefin, acrylate resin, methacrylate resin, norbornene resin, and styrene resin.

  The colored particles preferably contain a charge control agent. As the charge control agent, a charge control agent conventionally used for toner can be used without any limitation. Among the charge control agents, it is preferable to use a charge control resin. The charge control resin has high compatibility with the binder resin, is colorless, and a toner having stable chargeability can be obtained even in continuous color printing at high speed.

  The charge control resin includes a negative charge control resin and a positive charge control resin, which are selectively used depending on whether the toner of the present invention is a negatively chargeable toner or a positively chargeable toner. Hereinafter, the negative charge control resin and the positive charge control resin will be described.

  Examples of the negative charge control resin include a resin having a substituent selected from a carboxyl group or a salt thereof, a phenol group or a salt thereof, a thiophenol group or a salt thereof, a sulfonic acid group or a salt thereof in a polymer side chain. Is mentioned.

  Among these, a resin having a sulfonic acid group or a salt thereof in the side chain of the polymer is preferably used. Specific examples include a resin obtained by copolymerizing a monovinyl monomer containing a sulfonic acid group or a salt thereof and another monovinyl monomer copolymerizable with the monovinyl monomer. Examples of other monovinyl monomers that can be copolymerized include ethylenically unsaturated carboxylic acid ester monomers, aromatic vinyl monomers, and ethylenically unsaturated nitrile monomers.

  The compounding amount of the monovinyl monomer containing a sulfonic acid group or a salt thereof is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight in the negative charge control resin. When the blending amount of the monovinyl monomer containing a sulfonic acid group or a salt thereof is less than 0.5% by weight, the chargeability and the dispersibility of the colorant may be insufficient, and the print density and transparency may decrease. If it exceeds 15% by weight, the decrease in charge amount under high temperature and high humidity becomes large, and fogging may occur.

Examples of the positive charge control resin include amino such as —NH ₂ , —NHCH ₃ , —N (CH ₃ ) ₂ , —NHC ₂ H ₅ , —N (C ₂ H ₅ ) ₂ , —NHC ₂ H ₄ OH. Resins containing groups, and resins containing functional groups that are ammonium salified. Such a resin is obtained, for example, by copolymerizing a monovinyl monomer containing an amino group and a monovinyl monomer copolymerizable therewith. Further, the copolymer obtained as described above can be obtained by ammonium chloride. Furthermore, although obtained by copolymerizing a monovinyl monomer containing an ammonium base and a monovinyl monomer copolymerizable therewith, it is not limited to these methods. In order to obtain a negative charge control resin, a monovinyl monomer copolymerizable with a monovinyl monomer containing an amino group or a monovinyl monomer copolymerizable with a monovinyl monomer containing an ammonium base What is used is mentioned.

  The amount of the monovinyl monomer having a functional group such as an amino group and an ammonium base is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight in the positive charge control resin. If the content of the monovinyl monomer having a functional group is less than 0.5% by weight, the chargeability and the dispersibility of the colorant may be insufficient, and the print density and transparency may be reduced. If it exceeds 1, the decrease in the charge amount under high temperature and high humidity becomes large, and fogging may occur.

  The charge control resin preferably has a weight average molecular weight of 2,000 to 30,000, more preferably 4,000 to 25,000, and most preferably 6,000 to 20,000.

  The glass transition temperature of the charge control resin is preferably 40 to 100 ° C, more preferably 45 to 80 ° C, and most preferably 45 to 70 ° C. When the glass transition temperature is less than 40 ° C., the storage stability of the toner is deteriorated, and when it exceeds 100 ° C., the fixability may be lowered.

As release agents, polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; natural waxes such as candelilla, carnauba, rice, wood wax, and jojoba; petroleum waxes such as paraffin, microcrystalline, and petrolatum And synthetic waxes such as Fischer-Tropsch wax; polyfunctional esters such as pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrapalmitate, dipentaerythritol hexamyristate, and dipentaerythritol hexastearate Compound; and the like.
A mold release agent can be used 1 type or in combination of 2 or more types.

  The colored particles can be so-called core-shell type particles obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles. In the core-shell type particle, the low softening point material in the inside (core layer) is coated with a material having a higher softening point, so that it is possible to balance the lowering of the fixing temperature and the prevention of aggregation during storage. preferable.

  The core layer of the core-shell type particle is usually composed of the binder resin, the colorant, the charge control resin, and the release agent. On the other hand, the shell layer is usually composed only of a binder resin, but may further contain a colorant.

  In the case of core-shell type particles, the glass transition temperature of the polymer constituting the core layer is preferably 0 to 80 ° C, more preferably 40 to 60 ° C. When the glass transition temperature exceeds the above range, the minimum fixing temperature may be increased. On the other hand, when the glass transition temperature is less than the above range, the storage stability may be deteriorated.

  Further, the glass transition temperature of the polymer constituting the shell layer needs to be set to be higher than the glass transition temperature of the polymer constituting the core layer. The glass transition temperature of the polymer constituting the shell layer is preferably 50 to 130 ° C, more preferably 60 to 120 ° C, and most preferably 80 to 110 ° C in order to improve the storage stability of the toner. is there. When the glass transition point is less than the above range, the storage stability may be lowered. On the other hand, when it exceeds the above range, the minimum fixing temperature may be increased.

  The difference between the glass transition temperature of the polymer constituting the core layer and the glass transition temperature of the polymer constituting the shell layer is preferably 10 ° C or higher, more preferably 20 ° C or higher, and 30 ° C or higher. Most preferably it is. If it is smaller than this difference, the balance between storage stability and fixability may be lowered.

The weight ratio of the core layer to the shell layer of the core-shell type particle is not particularly limited, but the weight ratio of the core layer / shell layer is preferably 80/20 to 99.9 / 0.1.
When the ratio of the shell layer is smaller than the above ratio, the storage stability is deteriorated. Conversely, when the ratio is larger than the above ratio, fixing at a low temperature may be difficult.

  The volume average particle diameter (Dv) of the colored particles is preferably 4 to 9 μm. If (Dv) is less than the above range, the toner passes through between the photosensitive drum and the cleaning blade in the cleaning process, and the cleaning property is deteriorated. Durability of printing (i.e., printing a large number of sheets with good printing without fogging on the developing roll or smudges on the printing surface due to poor development, lowering of print density, and poor printing) The performance that can maintain the performance) is often insufficient.

  The colored particles preferably have a volume average particle size (Dv) of 3 to 10 μm, and more preferably 4 to 8 μm. When (Dv) is less than the above range, the fluidity of the toner may be reduced, fogging may occur, transfer residue may occur, or cleaning performance may be deteriorated. There is a case.

  In the present invention, the method for measuring the above Dv is not particularly limited, but in the examples of the present specification, it was measured by a particle size measuring instrument (trade name: Multisizer, manufactured by Beckman Coulter, Inc.). The measurement with this multisizer was performed under the conditions of aperture diameter: 100 μm, medium: Isoton II, and number of measured particles: 100,000.

The average circularity of the colored particles is preferably 0.950 to 0.995, more preferably 0.960 to 0.995. If it is less than the above range, the dot reproducibility tends to be lowered and the image quality is deteriorated. On the other hand, if it exceeds the above range, the print density and the print failure are likely to be lowered due to the development failure on the developing roll.
This average circularity can be made within the above range relatively easily by using a phase inversion emulsification method, a dissolution suspension method, a polymerization method, or the like.

  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. Further, 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 toner. The average circularity is a value obtained when the toner is perfectly spherical. 1 is shown in this case, and the value becomes smaller as the surface shape of the toner becomes more complicated. For the average circularity, the circularity (Ci) of each particle measured for a particle group having a circle-equivalent diameter of 1 μm or more was determined for each of n particles from the following equation, and then the average circularity (Ca) was calculated from the following equation: Ask.

  Circularity (Ci) = perimeter of circle equal to projected area of particle / perimeter of projected particle image

  In the above formula, fi is the frequency of particles having a circularity Ci.

  The circularity and average circularity can be measured using a flow type particle image analyzer (manufactured by Sysmex Corporation, trade name: FPIA-1000 or trade name: FPIA-2000).

  The toner of the present invention uses at least the following first and second inorganic fine particles as external additives to be attached to the surface of the colored particles.

The first inorganic fine particles have an average circularity of 0.9 to 1.0, an average primary particle diameter of 80 to 300 nm, and a normalized photoelectron yield slope a (standardized photoelectron yield / excitation energy). ) Is an inorganic fine particle (A) having 20 to 60 (1 / eV).
The second inorganic fine particles are inorganic fine particles (B) having an average primary particle diameter of 5 to 80 nm.

  The external additive is usually appropriately selected from organic and inorganic fine particles for the purpose of improving fluidity and chargeability. In the present invention, the above-mentioned inorganic fine particles (A) and inorganic fine particles (B ) In combination, the cleaning property on the photoreceptor and the fluidity of the toner are improved and the chargeability is easily controlled, so that the occurrence of fog is suppressed, and the durability of printing and the reproducibility of dots are improved. A toner that is excellent and has excellent charge rise characteristics can be obtained.

  In addition, as long as the objective of this invention can be achieved, you may use the external additive which further combined another component with the said inorganic fine particle (A) and the inorganic fine particle (B).

  The inorganic fine particles (A) and (B) can be appropriately selected from inorganic fine particle materials conventionally used as external additives, and the inorganic fine particles (A) and the inorganic fine particles (B) are the same material. There may be. Specific examples of the material of the inorganic fine particles (A) and (B) include silica fine particles, alumina fine particles, titania fine particles, and the like, and silica fine particles are preferable.

  The inorganic fine particles (A) and (B) preferably have a degree of hydrophobicity measured by a methanol method of 30 to 90%, more preferably 40 to 80%. It is preferable to use silica fine particles having a hydrophobization degree within the above-mentioned range because the influence of the environment is small and the occurrence of fogging under high temperature and high humidity can be suppressed.

  As the hydrophobizing treatment, a known method, for example, a method of treating with an organic group-containing silane compound (silane coupling agent) (JP-A No. 46-5782, JP-A No. 58-132757 (corresponding US Pat. No. 4,585,723A)), And a method of treating with a siloxane compound (Japanese Patent Laid-Open No. 7-330324 (corresponding US document US Pat. No. 5,686,054A)).

In the present invention, the average circularity of the inorganic fine particles (A) is 0.9 to 1.0, more preferably 0.95 to 1.0, still more preferably 0.975 to 1.0.
The average primary particle diameter of the inorganic fine particles (A) that are the first inorganic fine particles is 80 to 300 nm, more preferably 100 to 250 nm, and still more preferably 110 to 200 nm. If it is less than this range, the cleaning property on the developing roll deteriorates, and the durability of printing becomes insufficient. On the other hand, when the average primary particle diameter of the inorganic fine particles (A) exceeds the above range, the release of the inorganic fine particles (A) from the colored particles increases, so that the toner fluidity is deteriorated, the toner chargeability is reduced, and the free particles As a result, the chargeability of the toner is liable to decrease due to adhesion of the inorganic fine particles (A) to the developing roll, and as a result, the image quality of the obtained image is deteriorated.

  If the average circularity of the inorganic fine particles (A) is less than the above range, the toner may damage the photoconductor when the transferred toner is removed by a cleaning blade. When the photosensitive member is damaged, the toner passes between the scratch and the cleaning blade at the time of cleaning, so that the cleaning property is deteriorated.

  The average primary particle diameter and average circularity of the inorganic fine particles (A) can be measured by the following methods. That is, an electron micrograph of each particle is taken, and the photograph is taken by an image processing analysis apparatus (manufactured by Nireco, trade name: Luzex IID). Under these conditions, the equivalent circle diameter and circularity corresponding to the projected area of the inorganic fine particles (A) are calculated, and the respective average values are obtained to be the average primary particle diameter and average circularity, respectively.

  The degree of liberation of the inorganic fine particles (A) from the colored particles is preferably 20% or less, and more preferably 10% or less. When the degree of liberation of the inorganic fine particles (A) from the colored particles exceeds the above range, the inorganic fine particles (A) are largely liberated from the colored particles, so that the toner transportability is deteriorated and the dot reproducibility is lowered. There is a case.

  In the present invention, the degree of liberation is determined as follows. After adding 1 g of toner and 50 ml of pure water to a 100 ml beaker and stirring and mixing, this beaker was set in an ultrasonic cleaner (trade name: 1510J-DTH, manufactured by Yamato Kagaku Co., Ltd.) at 36 ° C. for 10 minutes. Sonication (42 kHz, 90 W) is performed. The ultrasonically treated toner is collected, a SEM photograph of the toner is taken using a scanning electron microscope (SEM), and the number of inorganic fine particles (A) on the toner after the ultrasonic treatment is counted.

  Further, the number of inorganic fine particles (A) on the toner before ultrasonic treatment is also counted by SEM, and the degree of liberation is obtained by the ratio of the numbers as described below.

(Freeness) = {(Number of inorganic fine particles (A) on toner after ultrasonic treatment) / (Number of inorganic fine particles (A) on toner before ultrasonic treatment)} × 100

  As described above, the inorganic fine particles (B) that are the second inorganic fine particles preferably have an average primary particle diameter of 5 to 80 nm, more preferably 5 to 60 nm, and further preferably 7 to 50 nm. When the average primary particle diameter of the inorganic fine particles (B) is less than the above range or exceeds the above range, initial fog and initial print density decrease are likely to occur due to a decrease in toner fluidity.

  The average primary particle diameter of the inorganic fine particles (B) can be measured by the same method as the average primary particle diameter of the inorganic fine particles (A).

Usually, the amount of the inorganic fine particles is (0.1 to 3.0) parts by weight of the inorganic fine particles (A) and (0.1 to 3.0) of the inorganic fine particles (B) with respect to 100 parts by weight of the colored particles. ) Part by weight.
The amount ratio of the inorganic fine particles (A) to the inorganic fine particles (B) is usually (1: 3 to 3: 1) (weight ratio).

  As the inorganic fine particles (B), silica fine particles having a relatively small average primary particle diameter within a range of 5 to 80 nm, preferably 5 to 60 nm, and a relatively small average primary particle size. It is preferable to use large silica fine particles in combination. Specifically, the silica fine particles (B1) having an average primary particle diameter of 5 to 20 nm, preferably 7 to 18 nm, are added in an amount of 0.1 to 100 parts by weight of the colored particles. 2 parts by weight, preferably 0.2 to 1.5 parts by weight, and 0.2 to 3 parts by weight, preferably 0, of the silica fine particles (B2) having an average primary particle diameter of 25 to 80 nm, preferably 30 to 70 nm. It is preferable to use in combination at a ratio of 2 to 2.5 parts by weight, more preferably 1 to 2.5 parts by weight.

  When the amount of the small silica fine particles (B1) contained in the inorganic fine particles (B) is less than the above range, the dot reproducibility is liable to deteriorate due to the deterioration of the toner fluidity, while the amount of the silica fine particles (B1) is the above-mentioned amount. When the range is exceeded, the print density and the print defect are likely to be lowered due to the development failure on the developing roll.

  Further, if the amount of the large silica fine particles (B2) contained in the inorganic fine particles (B) is less than the above range, the durability of printing tends to be insufficient due to a decrease in cleaning properties, while the silica fine particles (B2) When the amount exceeds the above range, the toner fixability deteriorates.

  The toner of the present invention contains the above-mentioned inorganic fine particles (A) and (B) as colored particles and an external additive, and, if necessary, other particles or components such as a carrier that carries the colored particles. You may contain.

The toner of the present invention can be used for developing an electrophotography with the colored particles as the toner as it is, but in order to adjust the charging property, fluidity, storage property, etc. of the toner, a high-speed stirrer such as a Henschel mixer is used. Colored particles, external additives including inorganic fine particles (A) and (B), and other particles as required can be mixed to form a one-component toner.
In addition to colored particles, external additives including inorganic fine particles (A) and (B), and other particles as required, ferrite, iron powder, and the like can be obtained by various known methods. The carrier particles can be mixed to form a two-component toner.

  The slope a of the normalized photoelectron yield of the inorganic fine particles (A) is preferably 20 to 60 (1 / eV), more preferably 30 to 60 (1 / eV). If the slope a of the normalized photoelectron yield of the inorganic fine particles (A) is less than the above range, the change in characteristics due to the difference in the storage environment of the toner and the use environment in the actual machine such as a printer is large, and fogging due to insufficient initial charging occurs. Etc. occur. On the other hand, when the slope a of the normalized photoelectron yield of the inorganic fine particles (A) exceeds the above range, the inorganic fine particles (A) are liberated from the colored particles, and the obtained image quality may deteriorate.

  The first-order correlation coefficient between the normalized photoelectron yield and the excitation energy of the inorganic fine particles (A) in the range from the work function value X + 0.2 eV to the work function value X + 0.8 eV is 0.95 or more. It is preferable that

  In general, the slope of the normalized photoelectron yield is stable when the excitation energy is within the above range, but the nanoscale-sized inorganic fine particles having an average primary particle diameter of about 80 to 300 nm, such as the inorganic fine particles (A), are The normalized photoelectron yield is not necessarily highly stable, and even if the excitation energy is within the above range, the yield of the normalized photoelectron yield relative to the slope of the normalized photoelectron yield approximately specified from the measured value of the normalized photoelectron yield Variations in individual measured values of normalized photoelectron yield are relatively large.

  In the present invention, the inorganic fine particle (A) has a small variation in individual measured values of the normalized photoelectron yield with respect to the slope of the normalized photoelectron yield, that is, the normalized photoelectron yield within the above range. By using the one having a linear correlation coefficient between the rate and the excitation energy of 0.95 or more, the chargeability of the toner can be easily controlled.

  If the primary correlation coefficient of the inorganic fine particles (A) is less than the above value, the change in the charging characteristics of the toner due to the difference in the storage environment of the toner and the usage environment in the actual machine such as a printer is large. (In a high temperature / high humidity environment) For example, fog due to insufficient initial charging occurs in an environment of a temperature of 35 ° C. and a humidity of 80%.

  Here, the normalized photoelectron yield means a value obtained by multiplying the photoelectron yield per unit photon by a power of 0.5, and the slope a of the normalized photoelectron yield with respect to the excitation energy (standardized photoelectron yield / excitation energy) ( 1 / eV) means the slope shown in the graph with the excitation energy (eV) on the horizontal axis and the normalized photoelectron yield on the vertical axis.

  Also, the work function is the energy level of electrons intrinsic to the substance, and in the above graph in which the horizontal axis represents the excitation energy (eV) and the vertical axis represents the normalized photoelectron yield, the value of the normalized photoelectron yield is shown. Is the value of the change point (ie, the change point at which the slope of the normalized photoelectron yield occurs) that changes from a state in which almost no change occurs. In the present invention, the work function X (eV) of the inorganic fine particles (A) means an energy level that is a threshold value at which the inorganic fine particles (A) start to emit electrons.

  The primary correlation coefficient (r) between the normalized photoelectron yield and the excitation energy of the inorganic fine particles (A) is relative to the slope approximately determined from the actual measurement value of the normalized photoelectron yield at each value of the excitation energy. , Which is an index representing the variation of the actual measurement value, and is obtained by the following equation. Details of the primary correlation coefficient are described in, for example, Quality Control Course Revised Edition New Statistical Method (19th printing, 1999), Japanese Standards Association Shigeru Moriguchi, p206-p207. The closer the value of the primary correlation coefficient is to 1, the smaller the variation.

  The method of measuring the normalized photoelectron yield slope a and work function value X of the inorganic fine particles (A) is the same as the method of measuring the normalized photoelectron yield slope a and work function value X of the whole toner described later. is there.

  The linear correlation coefficient between the normalized photoelectron yield and the excitation energy of the inorganic fine particles (A) in the range of the excitation energy from the work function value X + 0.2 (eV) to the work function value X + 0.8 (eV). (R) measures the normalized photoelectron yield at the excitation energy value of 7 points every 0.1 (eV) in the range of excitation energy from X + 0.2 (eV) to X + 0.8 (eV), Calculations are made based on the measurement values obtained at these seven points.

  The external additive is located between the developing roll or the photoreceptor and the colored particles, and the inorganic fine particles (A) having a large particle size have a great influence on adhesion to the above-described member. By setting the slope a of the normalized photoelectron yield of the inorganic fine particles (A) within the above range, more preferably by setting the variation in the measured value of the normalized photoelectron yield with respect to the slope A within the above range. It is considered that the electrostatic adhesion force can be controlled within an appropriate range.

  In the present invention, the work function of the inorganic fine particles (A) is preferably 4.80 to 5.20 (eV), more preferably 4.9 to 5.1 (eV). If the work function is less than the above range, the durability of printing tends to be insufficient due to a decrease in cleaning properties. On the other hand, if the work function exceeds the above range, fogging or the like occurs.

  In the present invention, the work function (eV) of the inorganic fine particles (A) means an energy level that is a threshold value at which the inorganic fine particles (A) start to emit electrons.

  FIG. 2 shows a general tendency of a graph in which excitation energy (eV) is plotted on the horizontal axis and normalized photoelectron yield is plotted on the vertical axis in work function measurement. In this graph, a flat portion where the normalized photoelectron yield does not change continues in a region where the excitation energy is low, and the normalized photoelectron yield starts to increase rapidly when the excitation energy reaches a certain level. The excitation energy at this change point is the work function X (eV).

  In addition, the slope of the region where the rate of change of the graph in the region where the excitation energy is equal to or higher than the value of the work function X (eV) is stable is the slope a (1 / eV) of the normalized photoelectron yield with respect to the excitation energy. Accordingly, the flat portion where the normalized photoelectron yield does not change in the region where the excitation energy is low does not affect the value of the slope a.

  The method for measuring the work function X of the inorganic fine particles (A) is not particularly limited, but in the examples of this specification, the measurement was performed with a photoelectron spectrometer (trade name: AC-2, manufactured by Riken Keiki Co., Ltd.).

  Specifically, first, inorganic fine particles (A) were uniformly spread and placed on a measurement holder. Next, a 500 nW D2 (deuterium) light source is used as the UV light source, and the energy of the monochromatic incident light (spot size of 2 to 4 mm) is reduced from 3.4 (eV) to 6.2 (eV) to 0.3 (eV). Irradiation was performed while scanning every 1 (eV), and the normalized electron yield with respect to the excitation energy was determined.

  From the measured values obtained from the above measurement, the slope a of the normalized photoelectron yield with respect to the excitation energy of the inorganic fine particles (A) and the work function X were determined by the following method.

  First, the measured values obtained by the above measurement are plotted taking the excited energy on the horizontal axis and the normalized photoelectron yield on the vertical axis. Next, an appropriate number of measurement points are picked up from a flat area immediately before the plotted measurement value rises on the graph, and the normalized photoelectron yield values are averaged to obtain a baseline. Specifically, in the range of excitation energy of 4.2 to 4.7 (eV), an average value was obtained from the normalized photoelectron yield of 6 points every 0.1 (eV) and used as a baseline. Next, when the normalized photoelectron yield value continuously increased from the baseline value in the range of 0.3 (eV) (four points every 0.1 (eV)), A value 0.2 (eV) larger than the excitation energy value at the point where the rate value starts to rise (the first point among the four points) is regarded as the point at which the rate of change of the graph has started to stabilize. Then, from the value 0.2 (eV) larger than the value of the excitation energy at the point where the value of the normalized photoelectron yield starts to rise (the first of the four points), 0.7 (eV) A linear straight line was obtained in a range up to a large value, and the slope was determined as the slope a (1 / eV) of the normalized photoelectron yield with respect to the excitation energy. Furthermore, the excitation energy at the intersection of the primary line and the baseline was determined as the work function X (eV).

  Next, a method for producing the toner of the present invention will be described.

  The colored particles can be produced by a conventionally known method such as a pulverization method, a polymerization method, an association method, and a phase inversion emulsification method.

  In particular, when producing core-shell type particles, the colored particles obtained by any of the above methods are used as a core layer, and the spray-drying method, the interfacial reaction method, the in situ polymerization method, the layer separation method, etc. are conventionally known. By coating the shell layer by the above method, core-shell type colored particles can be obtained.

  Among these production methods, the average circularity is 1, that is, it is preferable to produce colored particles by a polymerization method from the viewpoint of obtaining colored particles close to a true sphere. When producing core-shell colored particles, the polymerization method It is preferable to coat the shell layer on the colored particles prepared by the in situ polymerization method.

Hereinafter, a method of producing colored particles to be a core layer by a polymerization method and further coating a shell layer by an in situ polymerization method will be described.
First, the colored particles serving as the core layer are prepared by dissolving or dispersing a colorant, a charge control agent, and other additives in a polymerizable monomer that is a raw material of the binder resin, to obtain a polymerizable monomer composition. After forming droplets in an aqueous dispersion medium containing a dispersion stabilizer, polymerize by adding a polymerization initiator, associate particles as necessary, and then filter, wash, dehydrate and dry Can be manufactured.

  In the present invention, a charge control resin composition produced by mixing a colorant and a charge control resin as a charge control agent in advance may be used. In that case, a coloring agent is 10-200 weight part normally with respect to 100 weight part of charge control resin, Preferably it is 20-150 weight part.

  Examples of the polymerizable monomer that is a raw material for the binder resin include a monovinyl monomer, a crosslinkable monomer, a crosslinkable polymer, and a macromonomer. These polymerizable monomers are polymerized to become a binder resin component in the colored particles.

  Examples of the monovinyl monomer include aromatic vinyl monomers such as styrene, vinyl toluene, and α-methylstyrene; (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Such as propyl acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and (meth) acrylamide (Meth) acrylic acid monomers; monoolefin monomers such as ethylene, propylene, and butylene; and the like (where "(meth) acrylic acid" is "acrylic acid" or "methacrylic acid" Represents that).

  The said monovinyl monomer may be used independently and may be used in combination of 2 or more type. Of these monovinyl monomers, an aromatic vinyl monomer alone or a combination of an aromatic vinyl monomer and a (meth) acrylic acid monomer is preferably used.

  When a crosslinkable monomer is used together with a monovinyl monomer, hot offset is effectively improved.

  Here, the crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds. Examples of such monomers include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; diethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate, and divinyl ether. A compound having two vinyl groups in the molecule; a compound having three or more vinyl groups in the molecule, such as pentaerythritol triallyl ether and trimethylolpropane triacrylate.

  The amount of these crosslinkable monomers used is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the monovinyl monomer.

In the present invention, a macromonomer can be used as a monomer. It is preferable to use a macromonomer together with a monovinyl monomer because the balance between storage stability and low-temperature fixability is improved. The macromonomer has a polymerizable carbon-carbon double bond at the end of the molecular chain, and is an oligomer or polymer having a number average molecular weight of preferably 1,000 to 30,000. If a toner having a number average molecular weight of less than 1,000 is used, the surface portion of the toner becomes soft and the storage stability may be lowered. On the other hand, when a polymer having a number average molecular weight exceeding 30,000 is used, the meltability of the macromonomer is deteriorated, and the fixability and the storage stability may be lowered.
Here, examples of the vinyl polymerizable functional group include an acryloyl group and a methacryloyl group. From the viewpoint of ease of copolymerization, a methacryloyl group is preferred.

  As the macromonomer, it is preferable to use a macromonomer that gives a polymer having a glass transition temperature higher than that of a polymer obtained by polymerizing the monovinyl monomer.

The amount of the macromonomer used is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, more preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the monovinyl monomer. Part. If the amount of the macromonomer used is less than the above range of parts by weight, the storage stability of the toner may be deteriorated. On the other hand, if the amount of the macromonomer used exceeds the above range, the fixability may be deteriorated.
Addition of an aluminum coupling agent as another additive is desirable from the viewpoint of improving the dispersion of the colorant.

  Moreover, it is preferable to add a molecular weight modifier as other additives. Examples of the molecular weight modifier include t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and mercaptan compounds such as 2,2,4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram Disulfides, and thiuram disulfide compounds such as tetraethylthiuram disulfide; The molecular weight modifier is usually used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the polymerizable monomer.

  As the dispersion stabilizer, known surfactants and inorganic / organic dispersants can be used, but it is preferable because the inorganic dispersant can be easily removed by post-treatment. Examples of inorganic dispersants include inorganic salts such as barium sulfate, calcium carbonate, and calcium phosphate; inorganic oxides such as silica, aluminum oxide, and titanium oxide; aluminum hydroxide, magnesium hydroxide, and ferric hydroxide. Inorganic hydroxides; and the like. Among these, the dispersion stabilizer containing a colloid of a particularly poorly water-soluble inorganic hydroxide can narrow the particle size distribution of the polymer particles, and has little persistence after washing the dispersion stabilizer, This is preferable because the image can be reproduced clearly.

  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-hydroxy) Ethyl) propionamide), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobis (2-methylpro) And azo compounds such as 2,2′-azobisisobutyronitrile; di-t-butyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2- Ethyl hexanoate, t-hexyl peroxy-2-ethyl hexanoate, t-butyl peroxypivalate, di-isopropyl peroxy Organic peroxides such as dicarbonate, di-t-butylperoxyisophthalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and t-butylperoxyisobutyrate Can be illustrated.

  The polymerization initiator is used in an amount of 0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

  As a specific method for forming the shell, a method for continuously polymerizing by adding a polymerizable monomer for the shell to the reaction system of the polymerization reaction performed to obtain the core particles, and another reaction system A method of polymerizing a polymerizable monomer, further associating and then filtering, washing, dehydrating and drying core particles obtained, adding a shell polymerizable monomer to this, and performing stepwise polymerization, etc. Can be mentioned.

  As the polymerizable monomer for the shell, it is preferable to use a monomer that forms a polymer having a glass transition temperature exceeding 80 ° C., such as styrene, acrylonitrile, and methyl methacrylate, alone or in combination of two or more. .

  Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide), and 2,2′- And azo initiators such as azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide). The amount of the water-soluble polymerization initiator is usually 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight with respect to 100 parts by weight of the polymerizable monomer for shell.

  The aqueous dispersion of colored particles obtained by polymerization is preferably removed by adding an acid or alkali and dissolving the dispersion stabilizer in water. When a colloid of a hardly water-soluble inorganic hydroxide is used as the dispersion stabilizer, it is preferable to adjust the pH of the 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.

  The method for filtering and dewatering the colored particles from the aqueous dispersion medium is not particularly limited. Examples thereof include a centrifugal filtration method, a vacuum filtration method, and a pressure filtration method. Of these, the centrifugal filtration method is preferred.

The image forming method of the present invention will be described below.
FIG. 1 is a diagram showing an example of the configuration of an image forming apparatus to which the electrostatic latent image developing toner of the present invention is applied. The image forming apparatus shown in FIG. 1 has a photosensitive drum 1 as a photosensitive member, and the photosensitive drum 1 is mounted so as to be rotatable in the direction of arrow A. The photoconductive drum 1 is provided with a photoconductive layer on a conductive support drum, and this photoconductive layer is, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, or the like. Composed. Among these, those composed of organic photoreceptors are preferable. The photoconductive layer is bound to a conductive support drum.

  Around the photosensitive drum 1, a charging roll 5 as a charging member, a light irradiation device 7 as an exposure device, a developing device 21, a transfer roll 9, and a cleaning blade 25 are arranged along the circumferential direction.

  A fixing device 27 is provided on the downstream side of the photosensitive drum 1 in the transport direction. The fixing device 27 includes a heat roll 27a and a support roll 27b.

  The recording material conveyance path is provided so as to pass between the photosensitive drum 1 and the transfer roll 9 and between the heat roll 27a and the support roll 27b.

  The process of forming an image using the image forming apparatus shown in FIG. 1 includes a charging process, an exposure process, a development process, a transfer process, a cleaning process, and a fixing process as described below.

  The charging step is a step of uniformly charging the surface of the photosensitive drum 1 positively or negatively by the charging member. In addition to the charging roll 5 shown in FIG. 1, there are a contact charging method in which charging is performed by a fur brush, a magnetic brush, a blade, and the like, and a non-contact charging method by corona discharge. It is also possible to replace it with a contact charging system or a non-contact charging system.

  In the exposure process, a light irradiation device 7 as an exposure device as shown in FIG. 1 irradiates the surface of the photosensitive drum 1 with light corresponding to the image signal, and the uniformly charged surface of the photosensitive drum 1 is irradiated. This is a step of forming an electrostatic latent image. Such a light irradiation device 7 includes, for example, an irradiation device and an optical system lens. Examples of the irradiation device include a laser light irradiation device and an LED irradiation device.

  The development step is a step of attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 1 by the exposure step by the developing device 21. In the reverse development, the toner is attached only to the light irradiation portion, In regular development, the polarity of toner charging is selected so that the toner is attached only to the non-irradiated portion.

  A developing device 21 provided in the image apparatus shown in FIG. 1 is a developing device used in a one-component contact developing system, and includes a stirring blade 18, a developing roll 13, and a supply roll 17 in a casing 23 in which toner 19 is accommodated. And have.

  The developing roll 13 is disposed so as to partially contact the photosensitive drum 1 and is rotated in the direction B opposite to the photosensitive drum 1. The supply roll 17 comes into contact with the development roll 13 and rotates in the same direction C as the development roll 13, receives the supply of toner charged by the stirring blade 18 in the toner tank 23 a, and supplies toner to the outer periphery of the supply roll 17. The toner 19 is supplied to the outer periphery of the developing roll 17 by being attached. Other development methods include a one-component non-contact development method, a two-component contact development method, and a two-component non-contact development method.

  Around the developing roll 13, a developing roll blade 15 as a toner layer thickness regulating member is disposed at a position between the contact point with the supply roll 17 and the contact point with the photosensitive drum 1. The developing roll blade 15 is made of, for example, a conductive rubber elastic body or metal.

  The transfer process is a process of transferring the toner image on the surface of the photosensitive drum 1 formed by the developing device 21 to a recording material 11 such as paper, and is normally transferred to a transfer roll 9 as shown in FIG. In addition, there are belt transfer and corona transfer. In addition, as a recording material in the present invention, an OHP sheet, other transparent films, etc. can be used besides paper.

The cleaning step is a step of cleaning the toner remaining on the surface of the photosensitive drum 1, and a cleaning blade 25 is used in the image forming apparatus shown in FIG.
The cleaning blade 25 is made of a rubber elastic body such as polyurethane and acrylonitrile-butadiene copolymer.

  In the image forming apparatus shown in FIG. 1, the surface of the photosensitive drum 1 is uniformly charged negatively by the charging roll 5, and then an electrostatic latent image is formed by the light irradiation device 7. The toner image is developed by 21. Next, the toner image on the photosensitive drum 1 is transferred to a recording material such as paper by the transfer roll 9, and the transfer residual toner remaining on the surface of the photosensitive drum 1 is cleaned by the cleaning blade 25, Thereafter, the next image forming cycle starts.

  The fixing step is a step of fixing the toner image transferred to the recording material 11. In the image forming apparatus shown in FIG. 1, at least one of a heat roll 27a and a support roll 27b heated by a heating means (not shown) is rotated. Then, the recording material 11 is heated and pressed between them.

  The image forming apparatus shown in FIG. 1 is for monochrome use, but the toner of the present invention can also be applied to a color image forming apparatus such as a copying machine or a printer that forms a color image.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited only to a following example.

  Parts and% are based on weight unless otherwise specified.

  In the following description, (H / H) is an environment of (high temperature / high humidity), (N / N) is an environment of (normal temperature / normal humidity), and (L / L) is ( This symbol represents an environment of low temperature / low humidity.

<Test method>
The test methods performed in this example are as follows.

<Evaluation of physical properties of toner>

(1) Particle size of colored particles The volume average particle size (Dv) and the number average particle size (Dp) were measured with a particle size measuring instrument (Beckman Coulter, trade name: Multisizer). The measurement with this multisizer was performed under the conditions of aperture diameter: 100 μm, medium: Isoton II, and number of measured particles: 100,000.

(2) Average primary particle diameter of inorganic fine particles The average primary particle diameter of inorganic fine particles was measured by the following method. That is, an electron micrograph of inorganic fine particles is taken, and the photograph is taken by an image processing analysis apparatus (manufactured by Nireco, trade name: Luzex IID). Under these conditions, the equivalent circle diameter corresponding to the projected area of the inorganic fine particles was calculated for each particle, and the average value was obtained.

(3) Average circularity Into a container, 10 ml of ion-exchanged water is put in advance, 0.02 g of a surfactant (alkyl benzene sulfonic acid) as a dispersant is added, 0.02 g of toner is further added, and ultrasonic dispersion is performed. The dispersion treatment was carried out at 60 W for 3 minutes. The concentration of colored particles at the time of measurement is adjusted to 3,000 to 10,000 particles / μL, and a flow type particle image analyzer (SIMEX) is used for 1,000 to 10,000 colored particles having an equivalent circle diameter of 1 μm or more. The product name was measured using a product name: FPIA-1000. The average circularity was determined from the measured value.

  The circularity for one particle is shown in the following formula, and the average circularity is an average of the average circularity.

(Circularity) = (Perimeter of circle equal to projected area of particle) / (Perimeter of particle projection image)

(4) Normalized photoelectron yield slope a with respect to excitation energy, work function X
The measurement was performed with Riken Keiki AC-2. The inorganic fine particles (A) were uniformly spread on the measurement holder. The UV light source uses a 500 nW D ₂ (deuterium) light source, and the energy of monochromatic incident light (spot size of 2 to 4 mm) is 0.1 (eV) from 3.4 (eV) to 6.2 (eV). ) And scanning, and the normalized photoelectron yield relative to the excitation energy was determined.

  From the measured values obtained from the above measurement, the slope a of the normalized photoelectron yield with respect to the excitation energy of the toner and the inorganic fine particles (A) and the work function X were determined by the following method. First, in the range of excitation energy of 4.2 to 5.2 (eV), an average value was obtained from the normalized photoelectron yield of 11 points every 0.1 (eV), and was used as a baseline. Next, when the normalized photoelectron yield value continuously increased from the baseline value in the range of 0.3 (eV) (four points every 0.1 (eV)), A linear line is obtained in a range of 6.2 (eV) from a value 0.2 (eV) larger than the excitation energy value at the point where the value of the rate starts to rise, and the slope is normalized photoelectron yield with respect to the excitation energy. Slope a (1 / eV). Furthermore, the excitation energy at the intersection of the primary line and the baseline was determined as the work function X (eV).

(5) Primary correlation coefficient Normalized photoelectron yield and excitation energy in the range of the excitation energy of the inorganic fine particles (A) from the work function value X + 0.2 (eV) to the work function value X + 0.8 (eV) Is the normalized photoelectron yield at the excitation energy value of 7 points every 0.1 (eV) in the range of the excitation energy from X + 0.2 (eV) to X + 0.8 (eV). Was calculated based on the measured values obtained at these seven points.

<Image evaluation>
Toners were evaluated by setting the toners produced in Examples and Comparative Examples described below on a commercially available color printer (printing speed 30 sheets / min, 1200 × 600 dpi).

(6) Fixability (fixing temperature, offset temperature)
A fixing test was performed using a printer modified so that the temperature of the fixing roll portion of the color printer could be changed. The fixing test was performed by changing the temperature of the fixing roll, measuring the toner fixing rate at each temperature, and determining the relationship between the temperature and the fixing rate. When printing, unless otherwise specified, the toner fixing amount (M / A) was adjusted to 0.50 mg / cm ² . M represents the weight of the fixed toner, and A represents the printing area.

  The fixing rate was calculated from the ratio of the image density before and after the tape peeling operation in the solid area (magenta color area) printed on the test paper with the printer. That is, when the image density before tape peeling is ID (front) and the image density after tape peeling is ID (back), the fixing ratio can be calculated from the following equation.

    Fixing rate (%) = (ID (back) / ID (front)) × 100

  Here, the tape peeling operation means that an adhesive tape (manufactured by Sumitomo 3M, trade name: Scotch Mending Tape 810-3-18) is applied to the black solid area of the test paper, and is attached by pressing with a 500 g steel roller. The adhesive tape is then peeled off in a direction along the paper at a constant speed. The image density was measured using a reflection type image densitometer (manufactured by Macbeth, trade name: RD914). In this fixing test, the minimum fixing roll temperature at which the fixing rate is 80% or more was defined as the minimum fixing temperature of the toner. Further, the temperature at which the fixing roll temperature was increased by 5 ° C. and the residual toner deposits due to hot offset could be confirmed on the fixing roll was defined as the offset temperature.

(7) Dot reproducibility Using the above-mentioned color printer, after standing overnight in a (N / N) environment at a temperature of 23 ° C. and a humidity of 50%, a continuous line image with 2 × 2 dot lines (width of about 85 μm). Was measured by a printing evaluation system (trade name: RT2000, manufactured by YA-MA Co.) every 500 sheets, and density distribution data of a line image was collected.

  At this time, with the full width at the half maximum of the density as the line width and the line width of the first line image as a reference, if the difference in the line width is 10 μm or less, the first line image is reproduced. As a result, the number of lines that can maintain the line width difference of 10 μm or less was examined.

(8) Initial printing reflection density and initial printing reflection density reduction rate The toner was put in the printer and left overnight in a (N / N) environment at a temperature of 23 ° C. and a humidity of 50%. Continuous printing was performed from the beginning at a printing density of 5%, solid printing was performed at the time of printing the 10th sheet, and the N / N initial reflection printing density was measured using a Macbeth reflection type image density measuring machine. In the present invention, solid printing means printing with 100% printing density.

  Similarly, the toner was put in a printer and allowed to stand for 20 hours in a (H / H) environment at a temperature of 28 ° C. and a humidity of 80%, and then the H / H initial reflection print density was measured.

  Further, the reflection print density at the top of the solid and the reflection print density at the bottom of the solid were measured, and the reflection density reduction rate was obtained from these values. The reflection density reduction rate was calculated by the following formula.

(Reflection Density Reduction Rate) = [{(Reflection Print Density at the Top of Solid) − (Reflection Print Density at the Bottom of Solid)} / (Reflection Print Density at the Top of Solid)] × (100)

(9) Initial fog The toner was put in the above-mentioned printer and left for a whole day and night in an N / N environment, and then fog was measured. The fog was measured as follows.

  First, solid white printing is performed, and the printer is stopped halfway, and the toner in the non-image area on the developed photoreceptor is treated with adhesive tape (manufactured by Sumitomo 3M, trade name: Scotch Mending Tape 810-3-18). ) And affixed to new printing paper. The color tone was measured with a spectral color difference meter (manufactured by Nippon Denshoku Co., Ltd., trade name: SE-2000) at the portion where the toner in the non-image area was adhered. In the present invention, white solid printing means printing with 0% printing density.

Similarly, other than the place where the adhesive tape is pasted on the new printing paper, an unused adhesive tape is pasted as a reference, the color tone is measured in the same manner, and each tone is expressed as coordinates in the L × a × b space. The color difference ΔE was calculated from the color tone of the measurement sample and the color tone of the reference sample, and this value was used as the fog value. Smaller fog values indicate less fog and better image quality.
Similarly, the toner was put in a printer and allowed to stand for 20 hours in a (H / H) environment at a temperature of 28 ° C. and a humidity of 80%, and then the fog value was measured.

(10) Cleaning characteristics The test was performed using a modified machine in which the cleaning portion of the color printer was replaced with a cleaning blade. The cleaning blade was set with a set angle θ of 30 ° and an intrusion amount d of 1.2 mm. In this modified machine, the toners prepared in Examples and Comparative Examples described below were put and left for a whole day and night in an N / N environment or an L / L environment, respectively. Thereafter, continuous printing was performed at 5% density, and it was checked whether or not there was a cleaning failure up to 22,000 prints every 500 prints. The presence or absence of cleaning failure was observed by visually observing whether the toner slipped from the cleaning blade due to the cleaning failure adhered to the photosensitive member or the charging roll to cause streaks (filming).

(11) Freeness Using a scanning electron microscope (trade name: S-3000N, manufactured by Hitachi, Ltd.), an SEM photograph of the toner containing inorganic fine particles (A) is obtained under the condition of 10,000 magnifications. Photographed about the piece. The number of inorganic fine particles (A) adhering to the toner surface observed in this SEM photograph was counted.

  On the other hand, a sonicated toner was prepared. In the ultrasonic treatment, 1 g of toner and 50 ml of pure water were put into a 100 ml beaker, and after stirring, the beaker was set in an ultrasonic cleaner (trade name: 1510J-DTH, manufactured by Yamato Kagaku). Sonication (42 kHz, 90 W) was performed at 10 ° C. for 10 minutes.

  The toner subjected to the ultrasonic treatment is collected, and as described above, an SEM photograph of the toner containing the inorganic fine particles (A) is taken with respect to 20 toner particles, and the inorganic fine particles (A ) Was counted.

  The value obtained from the following formula was defined as the degree of liberation from the inorganic fine particles (A).

(Freeness) = {(Number of inorganic fine particles (A) on toner after ultrasonic treatment) / (Number of inorganic fine particles (A) on toner before ultrasonic treatment)} × 100

<Manufacture of fine particles for external additives>
(1) Production of spherical silica fine particles (1)

  (Step 1) 613.2 g of methanol, 38.6 g of water and 47.1 g of 28% ammonia water were added to and mixed with a 3 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer. While this solution was adjusted to 35 ° C. and stirred, 1082.3 g of tetramethoxysilane and 388.7 g of 5.4% aqueous ammonia were simultaneously added, and the former was added dropwise over 6 hours and the latter over 4 hours. After the tetramethoxysilane was added dropwise, stirring was continued for 0.5 hour to effect hydrolysis to obtain a silica fine particle suspension. Attach an ester adapter (distillation adapter) and a condenser tube to a glass reactor and heat to 60 to 70 ° C. to distill off 1150 g of methanol. Then, add 1200 g of water, and then heat to 70 to 90 ° C. to add 278 g of methanol. Distilled off to obtain an aqueous suspension of silica fine particles.

  (Step 2) To this aqueous suspension, 11.6 g of methyltrimethoxysilane (0.01 mol amount per 1 mol of tetramethoxysilane) was added dropwise at room temperature over 0.5 hours, and after the addition, the mixture was stirred for 12 hours to obtain silica. The surface of the fine particles was treated.

  (Step 3) 1440 g of methyl isobutyl ketone was added to the dispersion thus obtained, and then heated to 80 to 110 ° C. to distill away 1178 g of an aqueous methanol solution over 7 hours. To the resulting dispersion, 360.4 g of hexamethyldisilazane was added at room temperature, heated to 120 ° C. and reacted for 3 hours to trimethylsilylate the silica fine particles. Thereafter, the solvent was distilled off under reduced pressure to obtain 473 g of spherical hydrophobic silica fine particles having an average primary particle size of 120 nm (0.12 μm).

(2) Production of spherical silica fine particles (2) An average was obtained in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 32 ° C. instead of 35 ° C. during the synthesis of the spherical hydrophobic silica fine particles. 469 g of spherical hydrophobic silica fine particles having a primary particle diameter of 130 nm (0.13 μm) were obtained.

(3) Production of spherical silica fine particles (3) An amino-modified silicone oil was used in place of benzyltriethylammonium chloride as a treating agent for the spherical hydrophobic silica fine particles (2).

(4) Production of organic fine particles (1) 100 parts of styrene, 2.5 parts of sodium styrenesulfonate, 1.5 parts of sodium chloride, and 4000 parts of ion-exchanged water are added to and mixed with a nitrogen-substituted reaction vessel equipped with a stirrer. Then, the temperature was raised to 80 ° C. 500 parts of 3% aqueous solution of 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-086) as a polymerization initiator after the temperature rise Was added to initiate the polymerization. In the middle of measuring the polymerization conversion rate, when the conversion rate reached 30%, 0.1 part of t-dodecyl mercaptan was added, and the polymerization conversion rate measured after 7 hours from the start of polymerization was 98%. .

  Next, 400 parts of methyl methacrylate was added to the reaction system over 15 minutes, and the polymerization was further continued for 3 hours, followed by water cooling to stop the polymerization to obtain an aqueous dispersion of core-shell type organic fine particles. At this time, the polymerization conversion was 100%, the number average primary particle diameter of the organic fine particles was 380 nm (0.38 μm), and the sphericity was 1.13.

[Example 1]
Using the dispersion system shown in FIG. 3, the magenta colorant was finely dispersed in the polymerizable monomer. The dispersion system shown in FIG. 3 has a configuration in which the media-type disperser 101 and the holding tank 105 are connected by a lower circuit composed of lines 112 and 114 through which a liquid flows and an upper circuit composed of a line 115.

  In the holding tank 105, 1540 parts by weight of styrene as a monovinyl monomer and 340 parts by weight of butyl acrylate, 56 parts by weight of PR31 (CI Pigment Red 31) as a magenta colorant, and PR150 are used. 44 parts by weight of (CI Pigment Red 150) was added, and then 5 parts by weight of an aluminum coupling agent (acetoalkoxyaluminum diisopropylate, manufactured by Ajinomoto Fine Techno Co., Ltd., trade name: Plenact AL-M) was added. Then, dispersion was performed to prepare a mixed solution containing a polymerizable monomer, a magenta colorant, and an aluminum coupling agent.

  Next, 99.25 parts of the obtained mixed liquid was mixed with 3 parts of styrene, 3 parts of a charge control agent (styrene / acrylic resin, manufactured by Fujikura Kasei Co., Ltd., trade name: FCA-S748N), polymethacrylate macromonomer ( Toa Gosei Kagaku Kogyo Co., Ltd., trade name: AA6) 0.25 part and 10 parts of dipentaerythritol hexamyristate as a release agent were added and dissolved by stirring to prepare a polymerizable monomer composition.

  On the other hand, to an aqueous solution in which 6.5 parts of magnesium chloride is dissolved in 250 parts of ion-exchanged water, an aqueous solution in which 5 parts of sodium hydroxide is dissolved in 50 parts of ion-exchanged water is gradually added with stirring to obtain water as a dispersion stabilizer. Magnesium oxide colloid (slightly water-soluble metal hydroxide colloid) was produced to prepare a magnesium hydroxide colloid aqueous dispersion.

  To the magnesium hydroxide colloidal aqueous dispersion obtained above, the polymerizable monomer composition is charged, stirred, 2 parts of t-dodecyl mercaptan as a molecular weight modifier, 0.35 parts of divinylbenzene as a crosslinkable monomer, And 5 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) as a polymerization initiator, and an in-line type emulsifying disperser (trade name, manufactured by Ebara Corporation) : Ebara Milder) and high shear stirring at 15,000 rpm for 10 minutes to form droplets of the polymerizable monomer composition.

  An aqueous dispersion in which droplets of the polymerizable monomer composition are dispersed is placed in a reactor equipped with a stirring blade, the temperature is raised and polymerization is started, and the temperature is kept constant at 90 ° C. The temperature was controlled. After the polymerization conversion reached almost 100%, the polymerization temperature was kept as it was and 2,2 ′ dissolved in 1 part of methyl methacrylate as a polymerizable monomer for shell and 10 parts of ion-exchanged water as a polymerization initiator. -Azobis [2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide] (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA086) After continuing the reaction at 90 ° C. for 3 hours, the reaction was stopped to obtain an aqueous dispersion of colored particles having a core-shell structure. The pH of the aqueous dispersion was 9.5.

  While stirring the aqueous dispersion containing the colored particles obtained as described above, the pH of the aqueous dispersion is adjusted to 6 or less with sulfuric acid, acid washing (25 ° C., 10 minutes) is performed, and water is separated by filtration. 500 parts of ion exchange water was added to the slurry to make a slurry again, followed by washing with water. Thereafter, filtration, dehydration, and water washing were repeated several times, and then the solid content was separated by filtration to obtain wet colored polymer particles. The wet colored polymer particles were placed in a vacuum dryer container and vacuum dried at a pressure of 30 torr and a temperature of 50 ° C.

  The particle size distribution of the colored particles after drying is as follows: volume average particle size Dv = 6.9 μm, number average particle size Dp = 6.0 μm, particle size distribution Dv / Dp = 1.15, volume% of 16 μm or more = 1.9 %, Volume% of 20 μm or more = 1.0%, number% of 5 μm or less = 27.5%.

  To 100 parts of the above colored particles, 1.5 parts of spherical silica (1) is added as inorganic fine particles (A), and mixed at a rotation speed of 1,400 rpm for 3 minutes with a Henschel mixer preheated to 50 ° C. in the jacket. Thereafter, 1 part of silica fine particles (product name: R104, manufactured by Aerosil Co., Ltd.) is added as inorganic fine particles (B), and mixed at a rotational speed of 1,400 rpm for 5 minutes using a Henschel mixer. Obtained. This external addition method is called a heating two-stage external addition method.

[Example 2]
Example except that 2.3 parts of silica fine particles (manufactured by Clariant, trade name: HDK-05TX) are used in place of 1 part of silica fine particles (trade name: R104, manufactured by Aerosil Co., Ltd.) as the inorganic fine particles (B) The same operation as in Example 1 was performed to obtain a toner.

[Example 3]
1.5 parts of spherical silica (2) instead of 1.5 parts of spherical silica (1) as inorganic fine particles (A), and 1 part of silica fine particles (trade name: R104, manufactured by Aerosil) as inorganic fine particles (B) Instead, two types of inorganic particles, silica fine particles (Aerosil, trade name: R104) 0.6 parts (B1), and silica fine particles (Clariant, trade name: HDK-05TX) 2.3 parts (B2) A toner was obtained in the same manner as in Example 1 except that the fine particles B1 and B2 were used.

[Example 4]
A toner was obtained in the same manner as in Example 3 except that 1.5 parts of spherical silica (3) was used instead of 1.5 parts of spherical silica (2) as the inorganic fine particles (A).

[Example 5]
The same procedure as in Example 1 except that the external additive is added all at once without using the heating two-stage external addition method for heating the jacket, and mixing is performed at room temperature for 5 minutes without heating at 1,400 ppm. To obtain a toner. This external addition method is generally referred to as an external addition method.

[Example 6]
A toner was obtained in the same manner as in Example 5 except that in the normal external addition method of Example 5, the mixing time was 6 minutes.

[Comparative Example 1]
A toner was obtained in the same manner as in Example 3 except that the inorganic fine particles (A) were not used, and that external addition was performed by a normal external addition method instead of the two-stage heating external addition method.

[Comparative Example 2]
Instead of 1.5 parts of spherical silica (1) as inorganic fine particles (A), 1.5 parts of conductive titanium oxide fine particles (manufactured by Titanium Industry Co., Ltd., trade name: EC-300) are used. Instead, a toner was obtained in the same manner as in Example 1 except that the external addition was carried out by the usual external addition method.

[Comparative Example 3]
Comparative Example 2 except that 1.5 parts of organic fine particles (1) are used instead of 1.5 parts of conductive titanium oxide fine particles (trade name: EC-300, manufactured by Titanium Industry Co., Ltd.) as inorganic fine particles (A). The same operation was performed to obtain a toner.

〔result〕
The properties and images of the toners obtained in the examples and comparative examples were evaluated as described in the beginning of the examples. The results are shown in Table 1.

[Summary of results]
The toners obtained in Examples 1 to 6 have high dot reproducibility, high initial print reflection density, low initial print reflection density reduction rate, little fogging at the initial stage of printing, good cleaning properties, and neglect. The change in toner characteristics due to the environment was small.

  In contrast, the toner of Comparative Example 1 that does not use inorganic fine particles (A) has insufficient results in dot reproducibility, initial print reflection density reduction rate, initial fog when left in an H / H environment, and cleaning properties. It became. Further, the toner of Comparative Example 2 having a value outside the above range in terms of the slope of the normalized photoelectron yield and the degree of liberation was insufficient in the initial print reflection density reduction rate and the cleaning property. Further, the toner of Comparative Example 3 having values outside the above ranges in terms of average primary particle size, slope of normalized photoelectron yield, normalized photoelectron yield and primary correlation coefficient of excitation energy, freeness, and work function Resulted in insufficient results in dot reproducibility, initial fog when left in an H / H environment, and cleaning properties.

The electrostatic image developing toner of the present invention is a latent image having electrostatic characteristics such as an electrostatic latent image and a magnetic latent image in electrophotography, electrostatic recording method, electrostatic printing method, magnetic recording method and the like. It can be used as an electrostatic latent image developing toner used for development. More specifically, the image forming apparatus can be used as a toner for developing an electrostatic charge image that has a good cleaning property of the photosensitive member, a sufficient image density, and does not cause a development failure.

Claims (8)

In the toner for developing an electrostatic image containing colored particles and an external additive,
The external additive contains at least two kinds of inorganic fine particles;
The inorganic fine particles (A) that are the first inorganic fine particles have an average circularity of 0.9 to 1.0, an average primary particle diameter of 80 to 300 nm, and a normalized photoelectron yield of the inorganic fine particles A. The slope a (normalized photoelectron yield / excitation energy) is 20 to 60 (1 / eV),
The average primary particle diameter of the inorganic fine particles (B) as the second inorganic fine particles is 5 to 80 nm.
A toner for developing an electrostatic charge image.   The linear correlation coefficient between the normalized photoelectron yield and the excitation energy of the inorganic fine particles (A) in the range from the work function value X + 0.2 eV to the work function value X + 0.8 eV is 0.95 or more. The toner for developing an electrostatic charge image according to claim 1, wherein:   3. The electrostatic image developing toner according to claim 1, wherein the work function of the inorganic fine particles (A) is 4.80 to 5.20 (eV). As the inorganic fine particles (B) with respect to 100 parts by weight of the colored particles,
0.1 to 2 parts by weight of silica fine particles (B1) having an average primary particle diameter of 5 to 20 nm, and
The toner for developing an electrostatic charge image according to any one of claims 1 to 3, comprising 0.2 to 3 parts by weight of silica fine particles (B2) having an average primary particle diameter of 25 to 80 nm.   5. The electrostatic image developing toner according to claim 1, wherein the degree of liberation of the inorganic fine particles (A) from the colored particles is 20% or less.   6. The electrostatic image developing toner according to claim 1, wherein the colored particles contain a charge control resin.   7. The electrostatic image developing toner according to claim 1, wherein the colored particles are particles having a core-shell type structure. A developing step for forming a visible image on a photoreceptor with the electrostatic image developing toner according to any one of claims 1 to 7, and a transfer for transferring the visible image to a recording material to form a transferred image. And an image forming method comprising: a fixing step for fixing the transferred image.

Images