JP2003167374A - Negatively electrified toner, its producing method and image forming apparatus using negatively electrified toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce fogging toner and reversely transferred toner as much as possible, and also to improve the transfer efficiency, and to make electrification characteristic much more stable. <P>SOLUTION: Hydrophobic negatively electrified silica 13 and 14 whose average primary particle diameters are small and large, hydrophobic rutile anatase type titanium oxide 15, and hydrophobic positively electrified silica 16 whose particle diameter is the same or nearly the same as that of the silica 14 are respectively used as an additive 12 externally added to the toner base particles 8a of the negatively electrified toner 8. The silica 16 has positive electrifying property to the particles 8a so as to positively electrify the particles 8a. Thus, the silica 16 directly adheres to the surfaces of the particles 8a and achieves the function of micro-carrier, whereby the rise of the electrification of the particles 8a is quickened and the reversely transferred toner and fogging are effectively restrained. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image forming apparatus for forming an image by an electrophotographic method or the like, and is a component for developing an electrostatic latent image on a latent image carrier of the image forming apparatus. A negative-charged toner that belongs to the technical field of magnetic toners, and is a one-component non-magnetic toner obtained by adding at least an external additive having a negative chargeability to toner mother particles, a method for producing the same, and the negative-charged toner. It belongs to the technical field of the image forming apparatus used.

[0002]

2. Description of the Related Art Conventionally, as a toner used in an image forming apparatus, a two-component toner is generally known, which enables a relatively stable development, but a variation in a mixing ratio of a developer and a magnetic carrier. Is likely to occur and it is necessary to maintain it. Therefore, one-component non-magnetic toner has been developed. As this one-component non-magnetic toner, a one-component magnetic toner has been developed, but there is a problem that a clear color image cannot be obtained due to the opacity of the magnetic material. Therefore, a negatively charged toner, which is a one-component non-magnetic toner, has been conventionally developed as a color toner.

By the way, in the toner used in the image forming apparatus, a surface on which fine particles of an external additive are conventionally externally added to toner mother particles for the purpose of improving charging stability, fluidity, durability stability and the like. Processing is taking place.

Conventionally, as an external additive for toner, silicon dioxide (silica), aluminum oxide (alumina), and titanium oxide (titania), which have a negative charge property and impart negative polarity to toner mother particles, are used singly or in combination. Known to be used. In this case, it is general that each external additive is used in combination of two or more kinds in order to make full use of the characteristics possessed by each external additive.

However, even a toner using a plurality of kinds of external additives in combination as described above has the following problems. That is, even if an external additive is added to the toner, a charge amount distribution is present, so that even a negative charging toner cannot avoid the generation of positively charged toner. As a result, in an image forming apparatus that forms an image by negative charge reversal development, toner adheres to the non-image portion of the latent image carrier (photoconductor), which increases the amount of cleaning toner. Further, as the number of printed sheets increases, the external additive on the toner surface is buried, so that the amount of the external additive that functions effectively effectively decreases, and the fog toner amount further increases, and at the same time, the toner charge amount increases. And the toner scattering occurs. If a large amount of silica is added to maintain the fluidity of the toner in order to prevent the toner from deteriorating, the fluidity is improved but the fixability is deteriorated. When silica is increased, the negative charging ability of the toner becomes too high and the print image density decreases, so titania or alumina with a relatively low electrical resistance is added, but in general titania and alumina have a small primary particle size. However, when the number of printed sheets increases, the toner particles are buried in the toner mother particles, and their effects cannot be exhibited. In order to obtain a good full-color toner, generation of reverse transfer toner is required to be suppressed as much as possible.

Therefore, rutile type titanium oxide containing anatase type titanium oxide and having a treatment layer treated with a silane coupling agent is used as an external additive, and is attached to toner mother particles with spindle-shaped rutile type titanium oxide. The resulting titanium oxide is prevented from being buried in the toner mother particles, and the anatase type titanium oxide having a good affinity for the silane coupling agent is used to obtain a uniform coating of the silane coupling agent on the toner mother particles, whereby the charge distribution is improved. JP-A-2000-128534 proposes to obtain stable charging characteristics without lowering the triboelectrification property and to improve the environment dependency, fluidity and anti-caking property. According to the toner disclosed in this publication, the above problems (1) to (5) can be solved to some extent.

Further, by adding rutile / anatase mixed crystal type titanium oxide to hydrophobic silica as an external additive of the toner, the fluidity of the toner is enhanced without impairing the color reproducibility and transparency in a full color image. Japanese Patent Laid-Open No. 2001-83732 proposes that stable triboelectric chargeability is obtained regardless of temperature / humidity environment and that toner scattering is prevented to prevent toner fogging to a non-image area. There is. The toner disclosed in this publication can solve the above-mentioned problems 1 to a certain extent.

[0008]

However, in the toners of the above-mentioned respective publications, rutile type titanium oxide can prevent titanium oxide from being embedded in the toner mother particles, and can obtain stable charging characteristics to some extent. With
Although the anatase type titanium oxide can improve both the fluidity and the environment dependency, since the rutile / anatase type titanium oxide is simply used as an external additive, the characteristics of the rutile / anatase type titanium oxide,
In other words, it cannot be said that the characteristics that are difficult to be buried in the toner mother particles and the charge adjusting function are utilized more effectively, and there are limits to the stable charging characteristics that can be obtained, the improvement of fluidity, and the improvement of environmental dependence. Can be considered. That is, further improvement of the toner is required in order to more effectively solve the above problems (1) to (3).

The present invention has been made in view of the above circumstances, and an object thereof is to further reduce the fog toner and the reverse transfer toner in the non-image area and further improve the transfer efficiency, and further, the charging characteristics. (EN) Provided are a negatively charged toner capable of further stabilizing the above, a manufacturing method thereof, and an image forming apparatus using the negatively charged toner.

[0010]

In order to solve the above-mentioned problems, the negatively charged toner according to the invention of claim 1 is added with at least a negatively chargeable external additive having a negatively chargeable property with respect to toner mother particles. In the negatively charged toner formed as described above, a positively chargeable external additive having a positively chargeable property is added to the toner mother particles.

The negatively charged toner according to the invention of claim 2 is
It is characterized in that the total amount of all external additives including the positively chargeable external additive is set to 0.5 to 4.0% by weight based on the weight of the toner mother particles. Further, claim 3
The negatively charged toner according to the invention is characterized in that the negatively charged external additive is hydrophobic negatively charged silica and the positively charged external additive is hydrophobic positively charged silica.

Further, the negatively charged toner according to the invention of claim 4 is
The hydrophobic negatively-chargeable silica has an average primary particle size of negatively-chargeable silica having a small particle size and an average primary particle size of negatively-chargeable silica having a larger particle size than the small particle size, and the hydrophobic The positively chargeable silica is characterized in that the average primary particle diameter is the same as or almost the same as the negatively chargeable silica having the large particle diameter.

Further, the negatively charged toner according to the fifth aspect of the invention is
Hydrophobic rutile-anatase type titanium oxide having a work function which is substantially the same as the work function of the toner mother particles or larger than the work function of the toner mother particles is added, and the hydrophobic negatively chargeable silica is the hydrophobic It is characterized in that it is added in a larger amount than the total amount of the positively charged silica and the hydrophobic rutile-anatase type titanium oxide. Furthermore,
The negatively charged toner according to a sixth aspect of the invention is characterized in that the amount of the hydrophobic positively charged silica is set to 30% by weight or less of the total weight of the hydrophobic negatively charged silica.

Furthermore, the negatively charged toner according to the seventh aspect of the invention is
It is characterized in that it is a pulverization method toner using the toner mother particles produced by a pulverization method or a polymerization method toner using the toner mother particles produced by a polymerization method.
Further, the negatively charged toner of the invention of claim 8 has a circularity of 0.
It is characterized by being 91 or more. Further, claim 9
The negatively charged toner of the present invention has a number-based 50% diameter (D ₅₀ ).
Is 9 μm or less.

Furthermore, the method for producing the negatively charged toner according to the invention of claim 10 is the method for producing the negatively charged toner according to claim 5, wherein the toner mother particles and the negatively chargeable silica are first mixed. Then, the hydrophobic rutile-anatase type titanium oxide is added to and mixed with these mixtures, and the positively chargeable silica is further mixed to produce the negatively charged toner.

Further, in the image forming apparatus of the invention of claim 11, the negatively charged toner of claim 1 is used for each of the toners of cyan, magenta, yellow, and black, and an intermediate transfer medium is used. It is characterized by being a full-color image forming apparatus of the system. Further, the image forming apparatus according to the invention of claim 12 is characterized in that the intermediate transfer medium is an intermediate transfer medium comprising a belt.

[0017]

In the negatively charged toner of the present invention thus constructed and the image forming apparatus using the same, the toner mother particles to which at least the hydrophobic negatively chargeable external additive is added are By adding a hydrophobic positively-charged external additive having positive chargeability to the particles, the positively-charged external additive exerts the function of a microcarrier, which accelerates the rise of charging of the toner mother particles. The reverse transfer toner and fog are effectively suppressed.

Further, in the negatively charged toner of the present invention,
By using hydrophobic negatively charged silica in combination with hydrophobic positively charged silica and hydrophobic rutile anatase type titanium oxide, the work functions of negatively charged silica and positively charged silica become Since it is smaller, hydrophobic negatively charged silica and hydrophobic positively charged silica directly adhere to the toner base particles, and the work function of hydrophobic rutile-anatase type titanium oxide is the work function of the toner base particles. The hydrophobic rutile-anatase type titanium oxide is substantially the same as and has a work function larger than that of the hydrophobic negatively-charged silica. It comes to adhere to the surface.

Therefore, the characteristics of the hydrophobic rutile-anatase type titanium oxide, which are difficult to be embedded in the toner mother particles, and the charge adjusting function are more effectively utilized, and the negative charging performance of the hydrophobic negatively charging silica is improved. Further, the toner mother particles are provided with a function in which the unique characteristics of fluidity and fluidity and the unique characteristics of the hydrophobic rutile-anatase type titanium oxide such as relatively low resistance and negative antistatic property are synergized. As a result, the negatively charged toner is prevented from being deteriorated in fluidity and is prevented from being overcharged negatively, and thus has better negative charging characteristics.
Generation of reverse transfer toner and fogging are more effectively suppressed.

Moreover, by using two kinds of hydrophobic negatively chargeable silica having different average primary particle diameters, the negatively chargeable silica having a small particle diameter is embedded in the toner mother particles, and the work function of the negatively chargeable silica is obtained. Hydrophobic rutile-anatase type titanium oxide having a larger work function is less likely to be adhered to the negatively charged silica embedded in the contact potential difference due to the work function difference and to be released from the toner mother particles, and the large negative particle size of the hydrophobic negative Since the chargeable silica and the large-particle-diameter hydrophobic positively-charged silica are fixed on the surface of the toner mother particle, the surface of the toner mother-particle is large and small particles of the hydrophobic negatively-charged silica The positively charged silica and the hydrophobic rutile-anatase type titanium oxide are evenly covered, and the negatively charged toner has a stable negative charge for a longer period of time.
It provides more stable image quality in continuous printing. In particular, by adding at least the average amount of the hydrophobic negatively-chargeable silica having an average primary particle size of small particles to the total amount of the hydrophobic positively-chargeable silica and the hydrophobic rutile-anatase type titanium oxide, the negatively-charged toner is obtained. Negative charge is stable for a longer period of time. Therefore, the fogging of the non-image area is further suppressed, the transfer efficiency is further improved, and the generation of the reverse transfer toner is more effectively suppressed.

Further, in the case of adding positively chargeable silica as a fluidizing agent, the use of positively chargeable silica having a large particle size results in fixing as compared with the case of using positively chargeable silica having a small particle size. Fogging and reverse transfer toner are reduced.

Further, regardless of whether the toner is a pulverized toner or a polymerized toner, it is necessary to increase the addition amount of the hydrophobic negatively-charged silica when the toner particle size is reduced, but the addition amount of the hydrophobic negatively-charged silica is required. When the value is increased, not only the toner charge amount becomes too large in the initial stage, but also as the printing progresses, the hydrophobic negatively chargeable silica having a small particle size is buried or scattered, and the effectiveness of the hydrophobic negatively chargeable silica is increased. The surface amount is reduced, and the charge amount of the toner is reduced. For this reason, not only the reverse transfer toner and the fluctuation of the image density or the fogging amount increase, but also the toner consumption tends to increase. However, in the negatively charged toner of the present invention, there are two types of large and small hydrophobic particles. By using negatively chargeable silica, hydrophobic positively chargeable silica, and hydrophobic rutile anatase type titanium oxide in combination, the amount of hydrophobically negatively chargeable silica can be reduced, so that the reverse transfer toner, fluctuation in image density, And, the fogging of the non-image area can be more effectively suppressed.

Therefore, since the generation of the reverse transfer toner is more effectively suppressed, when the negatively charged toner of the present invention is used as a full color toner, the image density is maintained more uniform and for a longer period of time. . This results in high quality, full color images for extended periods of time.

Further, in the method for producing a negatively charged toner of the present invention, first, toner mother particles and negatively charged silica (negatively charged silica having large and small particle sizes) are mixed, and then these mixtures are mixed with hydrophobic rutile. By adding anatase type titanium oxide and mixing, and further by mixing positively chargeable silica,
Hydrophobic rutile-anatase type titanium oxide surely adheres to the surface of the toner base particles by adhering to the hydrophobic negatively charged silica attached to the toner base particles, and the positively charged silica directly adheres to the surface of the toner base particles. It becomes attached. As a result, the reverse transfer toner, the fog toner, and the negatively charged toner of the present invention capable of effectively suppressing the fluctuation of the image density are manufactured.

[0025]

1 is a diagram schematically showing an example of an embodiment of a negatively charged toner according to the present invention. Figure 1
As shown in, the negatively charged toner 8 in this example is a one-component non-magnetic toner, and is constituted by externally adding an external additive 12 to the toner mother particles 8a. The external additive 12 includes hydrophobic negatively-charged silica (S having a small average primary particle size and a large average particle size of 2 types).
iO ₂₎ 13, 14, the hydrophobic rutile-anatase type titanium oxide (TiO ₂₎ 15, and the large particle size hydrophobic negatively chargeable silica 14 and the same diameter or approximately the same size of the hydrophobic positively chargeable silica (SiO ₂ ) 16 are used respectively.

The average primary particle diameter of the hydrophobic negatively chargeable silica 13 having a small particle diameter is 20 nm or less, preferably 7 to 16 n.
m (this notation means 7 nm to 16 nm; the same applies to other units), and the average primary particle diameter of the hydrophobic negatively chargeable silica 14 having a large particle diameter is 30 nm or more, preferably Is set to 40 to 50 nm. Furthermore, in the hydrophobic rutile-anatase type titanium oxide 15, rutile type titanium oxide and anatase type titanium oxide are used in a predetermined mixed crystal ratio.
It can be manufactured by the manufacturing method disclosed in Japanese Patent No. 8534. This hydrophobic rutile-anatase type titanium oxide 15 has a spindle shape and its major axis diameter is 0.0
It is 2 to 0.10 μm, and the axial diameter ratio of the major axis and the minor axis is set to 2 to 8. Further, the average primary particle diameter of the hydrophobic charging silica 16 is the same as or substantially the same as the particle diameter of the hydrophobic negative charging silica 14 having the large particle size described above, and is set to 30 nm or more, preferably 40 to 50 nm. Has been done.

In the negatively charged toner 8 of this example, the hydrophobic negatively charged silica 13, which has a work function (illustration described later) smaller than that of the toner mother particles 8a,
The toner mother particles 8a are provided with a negative chargeability by 14 and are either larger than the work function of the toner mother particles 8a or substantially the same as the work function of the toner mother particles 8a (the work function difference is within 0.25 eV). Hydrophobic rutile-anatase type titanium oxide 15 having a certain work function (illustration will be given later)
By mixing and using, the toner base particles 8a are prevented from being overcharged.

The hydrophobic positively chargeable silica 16 is surface-treated to have a positive chargeability with a material such as aminosilane.
In addition, the work function of the whole is set smaller than the work function of the toner mother particles 8a. This hydrophobic positively chargeable silica 16 imparts a positive charge to the toner mother particles 8a.

The work function (Φ) is measured by a surface analyzer (AC-2, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW, and is the energy required to extract electrons from the substance. The smaller the work function, the easier it is to emit electrons, and the larger the work function, the less likely it is to emit electrons. for that reason,
When a substance with a low work function and a substance with a high work function are brought into contact with each other, a substance with a low work function is positively charged and a substance with a high work function is negatively charged. It is quantified as energy (eV).

The toner base particles used in the negatively charged toner 8 of this example thus constituted can be produced by either a pulverization method or a polymerization method. The production will be described below.

First, the production of a negatively charged toner (hereinafter referred to as a pulverizing toner) 8 using toner mother particles by the pulverizing method will be described. The pulverized toner 8 is obtained by uniformly mixing a pigment, a release agent, and a charge control agent in a resin binder with a Henschel mixer, melting and kneading with a twin-screw extruder, cooling, and then performing a coarse pulverization-fine pulverization step and classifying. A toner is obtained by externally adding a fluidity improving agent, which is an external additive, to the toner mother particles 8a obtained by the treatment.

As the binder resin, known toner resins can be used, and examples thereof include polystyrene and poly-.
α-methylstyrene, chloropolystyrene, styrene-
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer Polymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester-methacrylic acid ester copolymer, styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, styrene- A styrene resin such as a vinyl methyl ether copolymer, which is a homopolymer or copolymer containing styrene or a styrene substitute, a polyester resin, an epoxy resin, a urethane modified epoxy resin, a silicone modified epoxy resin, a vinyl chloride resin, a rosin modified malein. Acid resin, phenyl tree , Polyethylene, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, etc. Alternatively, they can be mixed and used. Particularly in the present invention, styrene-acrylic acid ester-based resin, styrene-methacrylic acid ester-based resin, polyester resin,
Epoxy resins are preferred. In the present invention, the binder resin preferably has a glass transition temperature of 50 to 75 ° C and a flow softening temperature of 100 to 150 ° C.

As the colorant, a known colorant for toner can be used. For example, carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6G, calco oil blue, quinacridone, benzidine yellow, rose bengal, malachite green lake, Quinoline yellow, C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment Red 122, C.I. I.
Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 184, C.I.
I. Pigment Yellow 12, C.I. I. Pigment
Yellow 17, C.I. I. Pigment Yellow 97,
C. I. Pigment Yellow 180, C.I. I. Solvent Yellow 162, C.I. I. Pigment Blue 5: 1, C.I. I. Pigment Blue 15: 3 and other dyes and pigments may be used alone or in combination.

As the release agent, a known release agent for toner can be used. Examples thereof include paraffin wax, microwax, microcrystalline wax, cadilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax and oxidized polypropylene wax. Among them, polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like are preferably used.

As the charge adjusting agent, a known charge adjusting agent for toner can be used. For example, oil black, oil black BY, Bontron S-22 (manufactured by Orient Chemical Industry Co., Ltd.), Bontron S-34 (manufactured by Orient Chemical Industry Co., Ltd.), salicylic acid metal complex E-81 (Orient Chemical Industry Co., Ltd.). , Thioindigo pigments, sulfonylamine derivatives of copper phthalocyanine, Spiron Black TRH (produced by Hodogaya Chemical Co., Ltd.), calixarene compounds, organic boron compounds, fluorine-containing quaternary ammonium salt compounds, monoazo metal complexes, Examples thereof include aromatic hydroxylcarboxylic acid-based metal complexes, aromatic dicarboxylic acid-based metal complexes, and polysaccharides. Among them, colorless or white ones are preferable for color toners.

As the fluidity improver which is an external additive, at least the above-mentioned hydrophobic negatively chargeable silica 1 having a small particle size is used.
3, the above-mentioned large particle size hydrophobic negatively charged silica 14, the above-mentioned hydrophobic rutile anatase type titanium oxide 15, and the large particle size negatively charged silica 14 and the same large particle size positively charged The silica 16 is used.
It is also possible to mix and use one or more other known flow improvers for inorganic and organic toners. Other known flow improvers for inorganic and organic toners include, for example, alumina, magnesium fluoride,
Silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride, magnetite, molybdenum disulfide, aluminum stearate, magnesium stearate, zinc stearate, calcium stearate, barium titanate, strontium titanate, etc. Fine particles of metal titanate and silicon metal salt can be used. These fine particles are silane coupling agents, titanium coupling agents, higher fatty acids,
It is preferably used after being hydrophobized with silicone oil or the like. Examples of other resin fine particles include acrylic resins, styrene resins, fluororesins, and the like.

Component ratio (weight ratio) in pulverized toner 8
Is shown in Table 1.

[0038]

[Table 1]

As shown in Table 1, the binder resin 100
The colorant is 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight, and the release agent is 1 to 10 parts by weight, preferably 2.5 to 8 parts by weight, based on parts by weight. Further, the charge control agent is 0.1 to 7 parts by weight, preferably 0.5 to 5 parts by weight, and the fluidity improver is 0.1 to 5 parts by weight, preferably 0.5 to 4 parts by weight. It is a department.

In the pulverized toner 8 of this example, it is preferable that the circularity is increased by the spheroidizing treatment for the purpose of improving the transfer efficiency. In order to increase the circularity of the pulverization toner 8, (A) in the pulverization step, an apparatus capable of pulverizing in a relatively round spherical shape, for example, a turbo mill known as a mechanical pulverizer (manufactured by Kawasaki Heavy Industries Ltd.) is used. The circularity can be up to 0.93. Alternatively, (B) crushed toner is a commercially available hot air spheronizing device surfing system SF
The circularity can be up to 1.00 by using S-3 type (manufactured by Nippon Pneumatic Mfg. Co., Ltd.).

Desirable circularity (sphericalization coefficient) of the pulverized toner 8 of this example is 0.91 or more, whereby good transfer efficiency can be obtained. And, the circularity can be cleaned by using a cleaning blade up to 0.97 and brush cleaning together if the circularity is more than 0.97.

In the pulverized toner 8 thus obtained, the average particle diameter (D ₅₀ ) which is the 50% diameter based on the number is set to 9 μm or less, preferably 4.5 to 8 μm. Thereby, the particle size of the pulverized toner 8 becomes a relatively small particle size. By using hydrophobic negatively chargeable silica and hydrophobic rutile anatase type titanium oxide as an external additive in the small particle size toner, Since the amount of the hydrophobic negatively chargeable silica can be made smaller than the amount of the hydrophobic negatively chargeable silica when the conventional silica fine particles are used alone, the fixability is improved. The average particle diameter and circularity of the toner particles and the like in the present invention are values measured by FPIA2100 manufactured by Sysmex Corporation.

Further, in the pulverized toner 8, the total amount (weight) of the external additives is 0.1 with respect to the weight of the toner mother particles.
The amount is set to 5% by weight or more and 4.0% by weight or less, preferably 1.0% to 3.5% by weight. As a result, when the pulverized toner 8 is used as a full-color toner, the effect of suppressing the generation of reverse transfer toner can be exhibited. The total amount of external additives is 4.
When it is added in an amount of 0% by weight or more, it is liberated from the toner surface,
It becomes a factor that deteriorates the fixability.

Next, the production of a toner (hereinafter referred to as a polymerization method toner) 8 using toner mother particles by a polymerization method will be described. Examples of the polymerization method toner 8 include a suspension polymerization method and an emulsion polymerization method. In the suspension polymerization method, a mixture in which a polymerizable monomer (monomer), a color pigment and a release agent are further added, if necessary, a dye, a polymerization initiator, a crosslinking agent, a charge control agent and other additives. The monomer composition obtained by dissolving or dispersing is added to an aqueous phase containing a suspension stabilizer (water-soluble polymer, poorly water-soluble inorganic substance) with stirring, granulated, and polymerized to obtain a desired composition. Colored polymerized toner particles having a particle size can be formed. Further, the toner can be prepared by using a dispersion polymerization method known as a similar method.

In the emulsion polymerization method, if necessary, a monomer and a releasing agent are further dispersed in water with a polymerization initiator, an emulsifier (surfactant), etc. to carry out polymerization, and then a colorant is added in the aggregation process. Colored toner particles having a desired particle size can be formed by adding a charge control agent and an aggregating agent (electrolyte). Regarding the materials used for preparing the polymerized toner, the same materials as those for the pulverized toner described above can be used for the colorant, the release agent, the charge control agent, and the fluidity improver.

As the polymerizable monomer (monomer), a known vinyl-based monomer can be used, and examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene and p-methylstyrene. -Methoxystyrene, p-ethylstyrene, vinyltoluene, 2,4-
Dimethylstyrene, pn-butylstyrene, p-phenylstyrene, p-chlorostyrene, divinylbenzene, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate. , Dodecyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, methacrylic acid n
-Octyl, dodecyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid,
Ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propyleneate, acrylonitrile, methacrylonitrile, vinylmethyl Ether, vinyl ethyl ether, vinyl ketone,
Examples thereof include vinyl hexyl ketone and vinyl naphthalene. Examples of the fluorine-containing monomer include 2,2
2-trifluoroethyl acrylate, 2,2,3,3
-Tetrafluoropropyl acrylate, vinylidene fluoride, ethylene trifluoride, tetrafluoroethylene, trifluoropropylene and the like can be used because the fluorine atom is effective for negative charge control.

Known emulsifiers (surfactants) can be used. For example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride. , Hexadecyltrimethylammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether and the like.

As the polymerization initiator, known ones can be used. For example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, etc. is there.

Known coagulants (electrolytes) can be used. Examples thereof include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, iron sulfate and the like.

Table 2 shows the component ratio (weight) of the emulsion polymerization toner 8.

[0051]

[Table 2]

As shown in Table 2, the polymerizable monomer 100
The amount of the polymerization initiator is 0.03 to 2, preferably 0.1 to 1 part by weight, and the surface active agent is 0.01 to 2 parts by weight.
0.1 parts by weight, 1 to 40 parts by weight of the release agent,
2 to 35 parts by weight, and the charge control agent is 0.1 to 7 parts by weight, preferably 0.5 to 5 parts by weight,
The colorant is 1 to 20 parts by weight, preferably 3 to 10 parts by weight, and the coagulant (electrolyte) is 0.05 to 5 parts by weight,
It is preferably 0.1 to 2 parts by weight.

Even in the case of the polymerized toner 8 of this example, the higher the circularity is, the better the transfer efficiency is. However, the circularity may be adjusted to improve the blade cleaning property. As a method for adjusting the circularity of the polymerization toner 8, the emulsion polymerization method (A) can freely change the circularity by controlling the temperature and time in the aggregation process of the secondary particles, and the range is 0. .
94 to 1.00. Further, in the (B) suspension polymerization method, since a spherical toner can be obtained, the circularity is 0.98 to 1.0.
The range is 0. Further, in order to adjust the circularity, the toner is heated and deformed at a temperature higher than the Tg temperature of the toner, so that the circularity is reduced to 0.
It is possible to freely adjust from 94 to 0.98.

Polymerization toner 8 can also be produced by a dispersion polymerization method other than the above-mentioned method, for example, JP-A-63-3040.
It can also be produced by the method disclosed in Japanese Patent Publication No. 02. In this case, since the shape is close to a true sphere, in order to control the shape, it is possible to press the toner at a temperature higher than the Tg temperature to obtain a desired toner shape.

As in the case of the pulverization toner 8 described above, the desired circularity (sphericalization coefficient) of the polymerization toner 8 of this example is used.
Is 0.95 or more, and a circularity up to 0.97 can be cleaned by using a cleaning blade, and a circularity of more than 0.97 can be cleaned by using brush cleaning together.

In the polymerization toner 8 thus obtained, the average particle diameter (D ₅₀ ) which is the 50% diameter on the number basis is set to 9 μm or less, preferably 4.5 to 8 μm. As a result, the particle size of the polymerized toner 8 becomes a relatively small particle size. By using hydrophobic negatively-charged silica and hydrophobic rutile-anatase type titanium oxide as external additives in this small particle size toner, Since the amount of the hydrophobic negatively chargeable silica can be made smaller than the amount of the hydrophobic negatively chargeable silica when the conventional silica fine particles are used alone, the fixability is improved. Even in the case of this polymerized toner 8, the average particle size and the circularity of the toner particles are
It is a value measured by FPIA2100 manufactured by Sysmex Corporation.

Further, also in this polymerization method toner 8, the total amount (weight) of the external additives is 0.5% by weight or more and 4.0% or more with respect to the weight of the toner mother particles, as in the above-mentioned pulverization method toner. weight%
It is set below, but preferably from 1.0% by weight to 3.
It is preferable to set it in the range of 5% by weight. As a result, when the polymerization toner 8 is used as a full-color toner, the effect of suppressing the generation of reverse transfer toner can be exhibited. If the total amount of the external additives is 4.0% by weight or more, it may cause scattering of the toner from the surface of the toner or deterioration of fixability.

In the negatively charged toner 8 of this example having such a configuration, both the polymerization method toner and the pulverization method toner have the hydrophobic negatively chargeable silica 13 having a small particle size as shown in FIG. It becomes easy to be buried in the mother particles 8a. The hydrophobic rutile-anatase type titanium oxide 15 having a work function larger than that of the hydrophobic negatively-charged silica 13 adheres to the buried hydrophobic negatively-charged silica 13 due to the contact potential difference due to the work function difference, and the toner mother particles 8a. Is less likely to be released from particles and has a large particle size and is a hydrophobic negatively charged silica 1
4 and the hydrophobic positively charged silica 16 having a large particle size are fixed to the surface of the toner mother particle 8a, the surface of the toner mother particle 8a is a negatively charged silica 13, 14,
It is evenly covered with the hydrophobic rutile-anatase type titanium oxide 15 and the hydrophobic positively charged silica 16.

Therefore, the characteristics of the hydrophobic rutile-anatase type titanium oxide 15 which are difficult to be buried in the toner mother particles 8a and the charge adjusting function can be more effectively utilized, and the hydrophobic negatively chargeable silica 13 is used. The toner has a function in which the unique characteristics of the negative charging performance and fluidity of the toners 14 and 14 and the unique characteristics of the hydrophobic rutile-anatase type titanium oxide 15 of the relatively low resistance and the negative antistatic property are synergized. It can be added to the mother particles 8a. As a result, it is possible to prevent the negatively charged toner 8 from being deteriorated in fluidity and to prevent negative overcharge, so that it is possible to obtain better negative charging characteristics, and as a result, the occurrence of reverse transfer toner and fogging are prevented. It can be effectively suppressed. Therefore, the negatively charged toner 8 is stable in its negative charge for a longer period of time and provides stable image quality in continuous printing.

In addition to this, since the positively chargeable silica 16 having a large particle size exerts the function of a microcarrier,
It is possible to accelerate the rise of charging of the toner mother particles 8a. As a result, the reverse transfer toner and fog are suppressed even more effectively. In particular, the addition amount (weight) of the positively charged silica 16 having a large particle size should be set to 30% or less of the total addition weight of the hydrophobic negatively charged silicas 13 and 14 so that the hydrophobic negatively charged silica 16 is added. This is preferable because the function of the positively chargeable silica 16 having a large particle diameter can be effectively exhibited without impairing the above-mentioned functions of 13 and 14.

Further, the hydrophobic negatively-charged silica 13,14
By adding more than the total amount (weight) of the hydrophobic rutile-anatase type titanium oxide 15 and the hydrophobic positively charged silica 16 (negative weight), the negative charge of the negatively charged toner 8 is stable for a longer period of time. To do. Therefore, the fogging of the non-image area is further suppressed, the transfer efficiency is further improved, and the generation of the reverse transfer toner is more effectively suppressed.

Further, even when the same amount of the fluidizing agent is added, the fixing property of the positively charged silica 16 having a large particle size is lower than that of the positively charged silica 16 having a small particle size. Fogging and reverse transfer toner are reduced.

FIG. 3 is a diagram schematically showing an example of a non-contact one-component developing system using the negatively charged toner 8 of this example.
FIG. 4 is a diagram schematically showing an example of a contact one-component developing system using the negatively charged toner 8 of this example. 3 and 4
Inside, 1 is an organic photoconductor, 2 is a corona charger, 3 is exposure, 4
Is a cleaning blade, 5 is a transfer roller, 6 is a supply roller, 7 is a regulating blade, 8 is negatively charged toner, 9 is a transfer material, 10 is a developing device, 11 is a developing roller, and L is a non-contact one-component developing process. Is the development gap.

The organic photoreceptor 1 may be an organic single layer type having a single organic photosensitive layer, or may be an organic laminated type having a plurality of organic photosensitive layers. As shown in FIG. 5 (a), the organic laminated type photoreceptor 1 comprises a conductive support 1 a, an undercoat layer 1 b, and
A photosensitive layer including a charge generation layer 1c and a charge transport layer 1d is sequentially laminated.

As the conductive support 1a, a known conductive support can be used, for example, volume resistance 10 ¹⁰ Ω · c.
Forming a conductive material having a conductivity of m or less, for example, a tubular material obtained by cutting or processing an aluminum alloy, a tubular material on which aluminum is vapor-deposited on a polyethylene terephthalate film or a conductive material is provided with a conductive paint, or a conductive polyimide resin. It can be formed from a tubular product made of.
As other shape examples, belt-shaped, plate-shaped, sheet-shaped supports and the like can be exemplified, and as other material and shape examples,
A metal belt or the like in which a nickel electroformed pipe or a stainless pipe is made seamless can also be suitably used.

As the undercoat layer 1b provided on the conductive support 1a, a known undercoat layer can be used. For example, the undercoat layer 1b is provided for the purpose of improving the adhesiveness, preventing moire, improving the coatability of the upper charge generation layer 1c, and reducing the residual potential during exposure. The resin used for the undercoat layer 1b is preferably a resin having a high resistance to dissolution in the solvent used for the photosensitive layer in view of coating the photosensitive layer having the charge generation layer 1c thereon. Usable resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, vinyl acetate,
Alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resin, and epoxy resin can be used alone or in combination of two or more kinds. Further, these resins may contain a metal oxide such as titanium dioxide or zinc oxide.

As the charge generating pigment in the charge generating layer 1c, known materials can be used. For example, phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine, azurenium salt pigment, squaric acid methine pigment, azo pigment having carbazole skeleton, azo pigment having triphenylamine skeleton, azo pigment having diphenylamine skeleton, dibenzothiophene skeleton Having an azo pigment, an azo pigment having a fluorene skeleton, an azo pigment having an oxadiazole skeleton, an azo pigment having a bisstilbene skeleton, an azo pigment having a distyryloxadiazole skeleton, an azo pigment having a distyrylcarbazole skeleton, and perylene Series pigments, anthraquinone series or polycyclic quinone series pigments, quinone imine series pigments, diphenylmethane and triphenylmethane series pigments, benzoquinone and naphthoquinone series pigments, cyanine and azomethine series pigments Indigoid pigments, and bisbenzimidazole pigments. These charge generating pigments can be used alone or in combination of two or more.

Examples of the binder resin in the charge generation layer 1c include polyvinyl butyral resin, partially acetalized polyvinyl butyral resin, polyarylate resin, vinyl chloride-vinyl acetate copolymer and the like.
The composition ratio of the binder resin and the charge generating material is 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin.
Used in the range of 0 parts by weight.

Known materials can be used as the charge-transporting material forming the charge-transporting layer 1d, and there are an electron-transporting material and a hole-transporting material. Examples of the electron transport substance include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, paradiphenoquinone derivative, benzoquinone derivative,
Examples thereof include electron-accepting substances such as naphthoquinone derivatives. These electron transport materials can be used alone or in combination of two or more.

Examples of the hole transport material include oxazole compounds, oxadiazole compounds, imidazole compounds, triphenylamine compounds, pyrazoline compounds, hydrazone compounds, stilbene compounds, phenazine compounds, benzofuran compounds, butadiene compounds, benzidine compounds, styryl compounds and Derivatives of these compounds are mentioned. These electron donating substances can be used alone or in combination of two or more.

The charge transport layer 1d may contain an antioxidant, an antiaging agent, an ultraviolet absorber or the like in order to prevent deterioration of these substances. As the binder resin in the charge transport layer 1d, polyester, polycarbonate, polysulfone, polyarylate, polyvinyl butyral, polymethyl methacrylate, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, silicone resin and the like can be used. Polycarbonate is preferable in terms of compatibility with the charge transport material, film strength, solubility, and stability as a coating material. The composition ratio of the binder resin to the charge transport material is 25 to 300 parts by weight based on 100 parts by weight of the binder resin.

In order to form the charge generation layer 1c and the charge transport layer 1d, a coating solution may be used, and the solvent varies depending on the kind of the binder resin, but for example, alcohols such as methanol, ethanol and isopropyl alcohol,
Ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ethers, esters such as methyl acetate and ethyl acetate Examples thereof include aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride and trichloroethylene, and aromatics such as benzene, toluene, xylene and monochlorobenzene. For dispersing the charge generation pigment, a sand mill,
Dispersion and mixing may be carried out using a mechanical method such as a ball mill, an attritor or a planetary mill.

The undercoat layer 1b, the charge generation layer 1c and the charge transport layer 1d can be applied by dip coating, ring coating, spray coating, wire bar coating, spin coating, blade coating or roller coating. A method such as an air knife coating method is used. Further, the drying after coating is performed at room temperature and then at a temperature of 30 to 200 ° C. for 30 to 120.
It is preferable to heat-dry for a minute. The film thickness after drying of the charge generation layer 1c is in the range of 0.05 to 10 μm,
It is preferably 0.1 to 3 μm. In addition, the charge transport layer 1
d is in the range of 5 to 50 μm, preferably 10 to 40 μm
Is.

The organic single-layer type photoreceptor 1 is shown in FIG.
As shown in the above, on the conductive support 1a explained in the above-mentioned organic laminated type photoreceptor 1, a charge generating agent, a charge transporting agent, a sensitizer and the like and a binder are provided through the same undercoat layer 1b.
It is prepared by coating and forming a single-layer organic photosensitive layer 1e made of a solvent or the like. The organic negative charging single layer type photoreceptor may be produced according to the method disclosed in, for example, JP-A-2000-19746.

Examples of the charge generating agent in the single-layer organic photosensitive layer 1e include phthalocyanine type pigments, azo type pigments, quinone type pigments, perylene type pigments, quinsiaton type pigments, indigo type pigments, bisbenzimidazole type pigments and quinacridone type pigments. However, phthalocyanine pigments and azo pigments are preferable. Examples of the charge transport agent include hydrazone-based, stilbene-based, phenylamine-based, arylamine-based, diphenylbutadiene-based, oxazole-based organic hole-transporting compounds, and the sensitizer includes various electron-withdrawing organic compounds. Which is also known as an electron transfer agent, a paradiphenoquinone derivative, a naphthoquinone derivative,
Examples include chloranil and the like. Examples of the binder include thermoplastic resins such as polycarbonate resin, polyarylate resin, and polyester resin.

The composition ratio of each component is 40 to 75 binders.
% By weight, charge generating agent 0.5-20% by weight, charge transporting agent 1
0 to 50% by weight, sensitizer 0.5 to 30% by weight, preferably 45 to 65% by weight binder, charge generator 1 to
20 wt%, charge transport agent 20-40 wt%, sensitizer 2
It is 25% by weight. As a solvent, for the undercoat layer,
A solvent having no solubility is preferable, and examples thereof include toluene, methyl ethyl ketone, and tetrahydrofuran.

The respective components are pulverized and dispersed and mixed with a stirring device such as a homomixer, a ball mill, a sand mill, an attritor and a paint conditioner to obtain a coating liquid. The coating solution is dip coated, ring coated, or
The film thickness after drying by spray coating or the like is 15 to 40 μm,
Preferably, the single-layer organic photoreceptor layer 1e is formed by coating and drying with a thickness of 20 to 35 μm.

The organic photoconductor 1 thus constructed has a diameter of 24 to 86 mm and a surface speed of 60 to 300 mm /
The photosensitive drum is a photosensitive drum that rotates at s, and the surface of the photosensitive drum is uniformly negatively charged by the corona charger 2 and then exposed 3 according to the information to be recorded. An image is formed.

The developing device 10 having the developing roller 11 is a one-component developing device 10, which supplies negatively charged toner 8 onto the organic photoconductor 1 to reversely develop the electrostatic latent image on the organic photoconductor 1. It is a visual image. In the developing device 10,
Negatively charged toner 8 is stored, and the toner is supplied to the developing roller 11 by the supply roller 6 which rotates counterclockwise as shown in FIG. The developing roller 11 rotates counterclockwise as shown in the figure, and in a state where the toner 8 conveyed by the supply roller 6 is adsorbed on the surface thereof, the developing roller 11 conveys the toner 8 to the contact portion with the organic photoreceptor 1 rotating clockwise, and The electrostatic latent image on the photoconductor 1 is visualized.

The developing roller 11 has a diameter of 16 to 24, for example.
mm, metal pipe plated or blasted with roller, or NBR, SBR, EPD on the central surface
A shaft made of M, urethane rubber, silicone rubber, etc., having a volume resistance value of 10 ⁴ to 10 ⁸ Ω · cm and a hardness of 40 to 70 ° (Asker A hardness) formed on it, and a shaft of this pipe. A developing bias voltage is applied from a power source (not shown) via the or central axis.

As the regulating blade 7, SUS, phosphor bronze, a rubber plate, a thin metal plate laminated with a rubber chip, or the like is used. It is pressed at a linear pressure of 20 to 60 gf / cm by utilizing the repulsive force as a body, the thickness of the toner layer on the developing roller 11 is 5 to 20 μm, preferably 6 to 15 μm, and the laminated form of the toner particles is about 1 to 2 The number of layers is preferably 1 to 1.8.

In the non-contact developing type image forming apparatus, the developing roller 11 and the organic photosensitive member 1 are opposed to each other via the developing gap L, but the developing gap L is 10
The developing bias of the direct current voltage (DC) is -200 to -50 (not shown).
It is 0V, and the AC voltage (AC) to be superimposed on it is 1.5 to 3.5kHz, PP voltage is 1000 to 1800V.
It is recommended that Also, in the non-contact development method,
As the peripheral speed of the developing roller 11 rotating counterclockwise,
1.0 to 2.0 with respect to the organic photoconductor 1 rotating clockwise.
The peripheral speed ratio is 5, preferably 1.2 to 2.2.

The developing roller 11 rotates counterclockwise as shown in the drawing, and the negatively charged toner 8 conveyed by the supply roller 6 is attracted to the surface thereof so that the negatively charged toner 8 is applied to the portion facing the organic photoconductor 1. Although conveyed, the negatively charged toner 8 vibrates between the surface of the developing roller 11 and the surface of the organic photoconductor 1 by superimposing and applying an AC voltage at a portion where the organic photoconductor 1 and the developing roller 11 face each other. To be developed. According to the present invention, the toner particles and the surface of the developing roller 11 can be brought into contact with each other while the toner 8 vibrates between the surface of the developing roller 11 and the surface of the organic photoconductor 1 by applying the AC voltage. Also, it is considered that the positively charged toner having a small particle size can be negatively charged and the fog toner can be reduced.

The transfer material 9 such as paper and the intermediate transfer medium (not shown in FIG. 3; shown as a medium-size transfer belt 36 in FIG. 6 described later) are the organic photoreceptor 1 and the transfer roller 5 which are visualized.
And the organic photoconductor 1 by the transfer roller 5.
The pressing load applied to the contact developing method is about 20 to 70
gf / cm, preferably 25 to 50 gf / cm.

Non-contact development process shown in FIG. 3 and FIG.
By combining the non-contact development process shown in (4) with a developing device and a photoreceptor 1 using four color toners (developer) of yellow Y, cyan C, magenta M, and black K, respectively.
The full-color image forming apparatus can form a full-color image. The full-color image forming apparatus is a four-cycle system (details will be described later) including four developing devices for four colors and one rotatable latent image carrier shown in FIG. 6 (four details will be described later) and each developing device for four colors and each latent image carrier. There are a tandem system in which the body and the body are arranged in a line, and a rotary system in which one latent image carrier and a rotatable developing device of four colors are combined.

Next, a preparation example of the negatively charged toner used in the image forming apparatus of the present invention, and the non-contact or contact one-component development shown in FIG. 6 having the basic structure shown in FIG. 3 using this negatively charged toner. An example of manufacturing the organic photoreceptor and the transfer medium of the image forming apparatus by the process will be described. Note that FIG.
The image forming apparatus shown in (1) can also perform a contact one-component developing process, and in the image forming test described later, a test by the contact one-component developing process was also performed using this image forming apparatus.
However, in the following description, this image forming apparatus basically performs the non-contact one-component developing process.

(Preparation Example of Negatively Charged Toner) Negatively Charged Toner 8
Both were prepared for both the above-mentioned polymerization method toner and pulverization method toner. In that case, the fluidity-improving agent (external additive) used in the preparation of the toner of each example had a major axis length of about 20.
nm, silane coupling-treated hydrophobic rutile-anatase type titanium oxide (20 nm), having a small particle size with an average primary particle size of 7 nm, hexamethyldisilane (H
Hydrophobic negatively charged vapor phase silica (7 nm) surface-treated with MDS), similarly small hydrophobicized negatively charged vapor phase silica (12 nm) having an average primary particle diameter of 12 nm. ), A small particle size having an average primary particle size of 16 nm, which is similarly hydrophobized negatively charged vapor phase silica (16 nm), and a large particle size having an average primary particle size of 40 nm, similarly hydrophobic Negatively Charged Vapor Phase Silica (40 nm), Hydrophobic Positively Charged Vapor Phase Silica (Surface Positively Charged with Aminosilane (AS) having a Large Particle Diameter of Average Primary Particle Diameter of 30 nm ( 30 nm) (silica shown in Table 4 below).
Further, for the comparative example of the present invention, the average primary particle size is 12
Two similarly hydrophobicized positively charged vapor phase process silicas (12 nm), (silica shown in Table 4 below), having a small particle size of nm, were also prepared. Table 3 shows the results of measuring these work functions Φ. Note that each work function Φ
Is a photoelectron spectrometer AC-2 manufactured by Riken Keiki Co., Ltd.
Was measured with an irradiation light amount of 500 nW.

[0088]

[Table 3]

As can be seen from Table 3, the work function Φ of each hydrophobized rutile-anatase type titanium oxide (20 nm) was 5.64 eV, and the normalized photoelectron yield at this time was 8.4. . In addition, negatively charged vapor phase method silica (7
work function Φ was 5.18 eV, and the normalized photoelectron yield was 6.1. Further, the work function Φ of the negatively chargeable vapor phase method silica (12 nm) was 5.22 eV, and the normalized photoelectron yield was 5.1. Furthermore, the work function Φ of the negatively chargeable vapor phase method silica (16 nm) was 5.19 eV, and the normalized photoelectron yield was 6.8. Furthermore, the work function Φ of negatively charged vapor phase silica (40 nm) is 5.24e.
V, and the normalized photoelectron yield was 5.2. Furthermore,
The work function Φ of the positively chargeable vapor phase method silica (30 nm) was 5.37 eV, and the normalized photoelectron yield was 11.5. Furthermore, positively charged vapor phase method silica (work function Φ at 12 nm is 5.13 eV, and normalized photoelectron yield is 10.7).
Met. Furthermore, positively charged silica (12 nm)
Has a work function Φ of 5.14 eV and a normalized photoelectron yield of 7.8.

(1) Preparation of Examples and Comparative Examples of Emulsion Polymerization Toner (a) Preparation of Emulsion Polymerization Toners of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 80 Styrene monomer 80 parts by weight, acrylic A water-soluble mixture of 20 parts by weight of butyl acid and 5 parts by weight of acrylic acid, 105 parts by weight of water, 1 part by weight of nonionic emulsifier, 1.5 parts by weight of anionic emulsifier, and 0.55 parts by weight of potassium persulfate. The mixture was added to the mixture, stirred under a nitrogen stream, and polymerized at 70 ° C. for 8 hours. After the polymerization reaction, the mixture was cooled to obtain a milky white resin emulsion having a particle diameter of 0.25 μm.

Next, 200 parts by weight of this resin emulsion, 20 parts by weight of polyethylene wax emulsion {manufactured by Sanyo Chemical Industry Co., Ltd.}, 7 parts by weight of phthalocyanine blue, and 0.2 parts by weight of sodium dodecylbenzenesulfonate as a surfactant. Parts in water, add diethylamine to adjust pH to 5.5, add 0.3 parts by weight of aluminum sulfate as an electrolyte with stirring, and then stir with TK homomixer at high speed to disperse. It was

Further, 40 parts by weight of a styrene monomer, 10 parts by weight of butyl acrylate, and 5 parts by weight of zinc salicylate were added together with 40 parts by weight of water, and the mixture was heated to 90 ° C. under stirring in a nitrogen stream in the same manner to perform peroxide Hydrogen was added and polymerized for 5 hours to grow particles. After the termination of the polymerization, in order to increase the association between the secondary particles and the film-forming bond strength, the temperature was raised to 95 ° C. while the pH was adjusted to 5 or higher, and the temperature was maintained for 5 hours. Thereafter, the obtained particles were washed with water and vacuum dried at 45 ° C. for 10 hours to obtain mother particles of cyan toner.

As a result of the measurement, the mother particles of the obtained cyan toner were toners having an average particle diameter of 6.8 μm and a circularity of 0.98, and the work function thereof was measured by the above-mentioned surface analysis device. It was 5.57 eV. With respect to the mother particles of the cyan toner, a negative particle size of negative charge having a mean primary particle size of about 7 nm of the negatively chargeable hydrophobic silica surface-treated with hexamethyldisilazane (HMDS), which is a fluidity improver, in a weight ratio An additive-mixed toner was prepared by adding 1% by weight of silica 13 and 1% by weight of negatively-charged hydrophobic silica which was similarly surface-treated and had a large particle size of negative-charged silica 14 having an average primary particle diameter of about 40 nm.

Then, three kinds of positively charged hydrophobic silica shown in Table 4 in which hydrophobic silica was surface-treated with aminosilane (AS) were prepared, and these positively charged hydrophobic silica were added to the above-mentioned additive mixed toner. Was added in an amount of 0.5% by weight to prepare the toner of Example 1 of the present invention and the toner of Comparative Examples 1 and 2, respectively. Further, a toner to which none of these positively-charged hydrophobic silica was added to the prepared mixed toner (that is, mixed toner) was used as the toner of Comparative Example 3.

[0095]

[Table 4]

As shown in Table 4, the positively chargeable hydrophobic silica (silica) used in the toner of Example 1 has a positively chargeable property with respect to the ferrite carrier of +150 μc / g and an average primary particle diameter of about 30 nm. Is. The positively chargeable hydrophobic silica (silica) used in the toner of Comparative Example 1 has a positively chargeable property of +2 with respect to the ferrite carrier.
80 μc / g, and the average primary particle size is about 12 nm
Is. Furthermore, the positively chargeable hydrophobic silica (silica) used in the toner of Comparative Example 2 has a positively chargeable property with respect to the ferrite carrier of +380 μc / g and an average primary particle diameter of about 12 nm. The work functions of the silica and the silica are smaller than the work function of the mother particles of the cyan toner, as is clear from the measurement results described above. The work functions of the toners of Example 1 and Comparative Examples 1 to 3 were 5.51 eV, 5.50 eV, and
It was 5.50 eV and 5.45 eV.

(B) Preparation of Emulsion Polymerization Toners of Example 2, Comparative Example 4, Comparative Example 5 and Comparative Example 6 In the preparation of the cyan emulsion polymerization toner of Example 1, instead of the phthalocyanine blue pigment In addition, the pigment was changed to quinacridone, and the temperature at which the association between the secondary particles and the film-forming bond strength was raised was 90 ° C. and the circularity was 0.9.
7, toner base particles of magenta toner having a work function of the toner base particles of 5.65 eV were prepared. Then, the external additive treatment is applied to the toner of Example 1 of the present invention and Comparative Examples 1 to 3
The same procedure as in the case of each of the above-mentioned toners was carried out to produce the respective toners of Example 2 of the present invention and Comparative Examples 4 to 6.
At this time, the respective work functions of silica and are smaller than the work function of the mother particles of the magenta toner, and the work functions of the toners of Example 2 and Comparative Examples 4 to 6 are 5. 59eV, 5.58e
V was 5.58 eV and was 5.53 eV.

(C) Preparation of Emulsion Polymerization Toner of Example 3 The cyan toner of the above-mentioned additive-mixed toner was hydrophobized with a silane coupling agent having a rutile-anatase type and a mixed crystal ratio of 10% rutile and 90% anatase type. Treated rutile-anatase type titanium oxide (hydrophobicity 58%, specific surface area 150 m ²
/ G) and 0.5% of silica shown in Table 4 were added and mixed to prepare a toner of Example 3 of the present invention. At this time, the work function of the rutile-anatase type titanium oxide is larger than the work function of each of the negatively chargeable silica 13, 14 and the positively chargeable silica 16, and is almost the same as that of the toner mother particles 8a of the cyan toner, or the work function thereof. It is set larger. As a result of specific measurement, the work function of rutile-anatase type titanium oxide is 5.64 eV.
And the work function of the toner of Example 3 is 5.5.
It was 8 eV.

(2) Preparation of Examples of Grinding Toner (a) Preparation of Grinding Toners of Examples 4, 5 and Comparative Examples 7 and 8 Aromatic dicarboxylic acid and alkylene etherified bisphenol A 100 parts by weight of a 50:50 (weight ratio) mixture (manufactured by Sanyo Chemical Industry Co., Ltd.) of a polycondensed polyester of 1: 1 and a partially crosslinked product of the polycondensed polyester with a polyvalent metal compound,
5 parts by weight of phthalocyanine blue as a cyan pigment, 3 parts by weight of polypropylene having a melting point of 152 ° C. and Mw of 4000 as a release agent, and 4 parts by weight of salicylic acid metal complex E-81 (manufactured by Orient Chemical Industry Co., Ltd.) as a charge control agent. After uniformly mixing the parts using a Henschel mixer, the internal temperature 15
The mixture was kneaded with a twin-screw extruder at 0 ° C. and cooled. The cooled product was roughly pulverized to 2 mm square or less, and the coarsely pulverized product was finely pulverized by a jet mill and classified by a classifier to obtain a toner having an average particle diameter of 7.6 μm and a circularity of 0.91. The work function of the toner base particles is 5.46e as a result of the measurement.
It was V.

Hexamethyldisilazane (HM), which is a fluidity improving agent, was added in a weight ratio to the obtained toner mother particles.
DS) surface-treated negatively-charged hydrophobic silica having an average primary particle size of about 12 nm is 0.8% by weight, and similarly surface-treated negatively-charged hydrophobic silica has an average primary particle size of about 4
0.5 wt% of 0 nm was added and mixed, and this added mixed toner was mixed with rutile anatase and had a mixed crystal ratio of rutile 10
Wt%, anatase type 90% rutile-anatase type titanium oxide hydrophobized with a silane coupling agent (hydrophobicity 58%, specific surface area 150 m ² / g) was added and mixed with 0.4% by weight and mixed toner Was produced.

Then, 0.2% of positively charged hydrophobic silica (silica) having a large particle size (average primary particle size: about 30 nm) shown in Table 4 obtained by surface-treating hydrophobic silica with aminosilane (AS) was added. By mixing, a toner of Example 4 of the present invention was manufactured. Further, 0.2% of positively charged hydrophobic silica (silica) having a small particle diameter (average primary particle diameter: about 12 nm) shown in Table 4 treated in the same manner was added and mixed to prepare a toner of Comparative Example 7. Further, a toner of Comparative Example 8 in which these positively charged hydrophobic silica was not added was prepared.

Further, instead of phthalocyanine blue, the pigment was changed to quinacridone, and toner mother particles were prepared in the same manner as described above. The work function of the prepared toner mother particles was 5.57 eV as a result of the measurement. The toner mother particles were subjected to an external additive treatment in the same manner as in Example 4 above to prepare a toner of Example 5 of the present invention. As a result of the measurement, Example 4, Example 5, Comparative Example 7 and Comparative Example 8
The work functions of the above toners are 5.45 eV and 5.
It was 56 eV, 5.44 eV and 5.46 eV.

(B) Preparation of pulverized toner of Examples 6 and 7 In accordance with the above-described preparation example of the toner of Example 4 of the present invention, pigment yellow yellow toner mother particles and carbon black were prepared using Pigment Yellow 180. To prepare black toner mother particles. As a result of the measurement, the work function of these toner base particles was found to be 5.62 eV for the yellow toner base particles and 5.72 eV for the black toner base particles. Then, the yellow toner mother particles and the black toner mother particles are subjected to the external additive treatment in the same manner as in the case of the toner of the above-described Example 4, and the toners of Examples 6 and 7 of the present invention are respectively obtained. Was produced. As a result of the measurement, the work functions of the toners of Examples 6 and 7 are 5.61 eV and 5.7, respectively.
It was 1 eV.

(Example of image forming apparatus by non-contact or contact one-component developing process) As an image forming apparatus by non-contact one-component developing process shown in FIG. 3 or an image forming apparatus by contact one-component developing process shown in FIG. There is a full-color printer capable of the non-contact development process and the contact development process shown in FIG. In FIG. 6 showing the full-color printer, 100 is an image carrier cartridge in which an image carrier unit is incorporated. In this example, the electrophotographic photoconductor for negative charging (hereinafter referred to as the electrophotographic photoconductor for a negative charge having a work function in the relative relationship of the present invention, which is configured as a photoconductor cartridge so that the photoconductor and the developing unit can be separately mounted (Also simply referred to as a photoconductor) 140 is rotationally driven in a direction indicated by an arrow by an appropriate driving unit (not shown).
Around the photoconductor 140 along the rotation direction thereof, a charging roller 160 as a charging unit and a developing device 1 as a developing unit.
0 (Y, M, C, K), the intermediate transfer device 30, and the cleaning unit 170 are arranged.

The charging roller 160 contacts the outer peripheral surface of the photoconductor 140 to uniformly charge the outer peripheral surface thereof. The exposure unit 40 selectively exposes L1 on the outer peripheral surface of the uniformly charged photoconductor 140 according to desired image information, and an electrostatic latent image is formed on the photoconductor 140 by this exposure L1. The electrostatic latent image is developed by the developing device 10 to which a developer is applied.

The developing device 10 for yellow is used as the developing device 10.
Y, magenta developing unit 10M, cyan developing unit 10
A developing device 10K for C and black is provided. These developing devices 10Y, 10C, 10M, and 10K are configured to be swingable. Then, selectively, only the developing roller (developer carrying member) 11 of one developing device
In the case of the non-contact developing process, the photosensitive drum 140 is set with a predetermined developing gap L, and in the case of the contact developing process, it can be pressed against the photosensitive member 140. These developing devices 10 hold negatively charged toner having a work function that is in a relative relationship with the work function of the photoconductor on the developing roller. These developing devices 10 are yellow Y, magenta M, and cyan. C, black K
One of the toners is applied to the surface of the photoconductor 140 to develop the electrostatic latent image on the photoconductor 140. The developing roller 11 is a hard roller, for example, a metal roller having a roughened surface. The developed toner image is transferred onto the intermediate transfer belt 36 which is an intermediate transfer medium of the intermediate transfer device 30. The cleaning unit 170 includes a cleaner blade that scrapes off the toner T adhering to the outer peripheral surface of the photoconductor 140 after the transfer, and a cleaning toner collecting unit that receives the toner scraped off by the cleaner blade.

The intermediate transfer device 30 includes a drive roller 31 and
Four driven rollers 32, 33, 34 and 35, and an endless intermediate transfer belt 36 stretched around these rollers.
And have. The drive roller 31 is rotationally driven at a peripheral speed substantially the same as that of the photoconductor 140 because a gear (not shown) fixed to the end of the drive roller 31 meshes with the drive gear of the photoconductor 140. Therefore, the intermediate transfer belt 36 is exposed to light. It is designed to be circulated and driven in the direction of the arrow in the figure at a peripheral speed substantially the same as that of the body 140.

Between the driven roller 35 and the driving roller 31, the intermediate transfer belt 36 is tensioned by itself, and the photosensitive member 1
The photoconductor 140 is arranged at a position where it is pressed against the photoconductor 40.
A primary transfer portion T1 is formed in a pressure contact portion between the intermediate transfer belt 36 and the intermediate transfer belt 36. The driven roller 35 is arranged near the primary transfer portion T1 on the upstream side in the circulation direction of the intermediate transfer belt.

An electrode roller (not shown) is arranged on the driving roller 31 via the intermediate transfer belt 36, and a primary transfer voltage is applied to the conductive layer of the intermediate transfer belt 36 via the electrode roller. The driven roller 32 is a tension roller, and biases the intermediate transfer belt 36 in its tension direction by a biasing means (not shown). Driven roller 3
A backup roller 3 forms a secondary transfer portion T2. The intermediate transfer belt 3 is attached to the backup roller 33.
The secondary transfer roller 38 is disposed so as to be opposed to each other with the sheet No. 6 interposed therebetween.
A secondary transfer voltage is applied to the secondary transfer roller so that the secondary transfer roller can be brought into contact with and separated from the intermediate transfer belt 36 by a contacting and separating mechanism (not shown). The driven roller 34 is a backup roller for the belt cleaner 39. Belt cleaner 39
Can be contacted and separated from the intermediate transfer belt 36 by a contacting and separating mechanism (not shown).

The intermediate transfer belt 36 is a multi-layer belt having a conductive layer and a resistance layer formed on the conductive layer and pressed against the photoconductor 140. The conductive layer is formed on an insulating base made of synthetic resin, and a primary transfer voltage is applied to the conductive layer via the electrode roller described above. At the side edge of the belt, the conductive layer is exposed in a strip shape by removing the resistive layer in a strip shape, and the electrode roller comes into contact with the exposed portion.

During the process in which the intermediate transfer belt 36 is circularly driven, the toner image on the photoconductor 140 is transferred onto the intermediate transfer belt 36 at the primary transfer portion T1, and the toner image transferred onto the intermediate transfer belt 36 is In the secondary transfer portion T2, the image is transferred onto a sheet (recording material) S such as a sheet supplied between the secondary transfer roller 38 and the secondary transfer roller 38. The sheet S is fed from the sheet feeding device 50 and is fed to the secondary transfer portion T2 at a predetermined timing by the gate roller pair G. Reference numeral 51 is a paper feed cassette, and 52 is a pickup roller.

The toner image secondarily transferred at the secondary transfer portion T2 is fixed by the fixing device 60, and discharged through the paper discharge path 70 onto the sheet receiving portion 81 formed on the case 80 of the apparatus main body. . Note that this image forming apparatus has two independent paper discharge paths 71 and 72 as the paper discharge path 70, and a sheet passing through the fixing device 60 passes through either paper discharge path 71 or 72. Is discharged. The paper discharge paths 71 and 72 also constitute a switchback path,
When images are formed on both sides of the sheet, the sheet that has once entered the sheet discharge path 71 or 72 is fed through the return roller 73 toward the secondary transfer portion T2 again.

Next, a manufacturing example of each component of the image forming apparatus will be described. (Organic photoconductor [1 in FIGS. 3 and 4 and 14 in FIG.
0] Production Example 1) In the production of the organic laminated type photoreceptor 1 of Production Example 1, first, as the undercoat layer 1b, alcohol-soluble is formed on the peripheral surface of the conductive support 1a having an aluminum tube diameter of 85.5 mm. A ring coating method was used to apply a coating solution obtained by dissolving and dispersing 6 parts by weight of nylon {“CM8000” manufactured by Toray Industries, Inc.} and 4 parts by weight of titanium oxide fine particles treated with aminosilane in 100 parts by weight of methanol. Then, it was dried at a temperature of 100 ° C. for 40 minutes to form an undercoat layer 1b having a film thickness of 1.5 to 2 μm.

Then, 1 part by weight of an oxytitanyl phthalocyanine pigment as a charge generating pigment, 1 part by weight of a butyral resin {BX-1, manufactured by Sekisui Chemical Co., Ltd.}, and 100 parts by weight of dichloroethane were added to glass beads having a diameter of 1 mm. A pigment dispersion is obtained by dispersing with the sand mill used for 8 hours, and the obtained pigment dispersion is applied onto the undercoat layer 1b by the ring coating method and dried at 80 ° C. for 20 minutes to obtain a film thickness of 0.1. A charge generation layer 1c of 3 μm was formed.

On the charge generation layer 1c, 40 parts by weight of a charge transporting substance of a styryl compound represented by the following structural formula (1) and a polycarbonate resin (Panlite TS, Teijin Chemicals Ltd.) were used.
Made by dissolving 60 parts by weight of toluene in 400 parts by weight of toluene, coating by a dip coating method so as to have a dry film thickness of 22 μm, and drying to form a charge transport layer 1d, and an organic layer having two photosensitive layers. A laminated photoreceptor 1 (OPC1) was produced. A part of the obtained organic laminated type photoreceptor 1 was cut out to form a sample piece, and the work function of this sample piece was irradiated by using a commercially available surface analyzer {AC-2 type, manufactured by Riken Keiki Co., Ltd.}. When measured with a light amount of 500 nW, it showed 5.48 eV.

[0116]

[Chemical 1]

(Production Example 2 of Organic Photoreceptor [1 in FIGS. 3 and 4 and 140 in FIG. 6]) In the production of the organic laminated type photoreceptor 1 of Production Example 2, the conductive support 1a has a seamless thickness. Using a nickel electroformed tube of 40 μm and a diameter of 85.5 mm,
An organic laminated photoreceptor 1 (OPC2) was produced in the same manner as in Production Example 1 except that the distyryl compound represented by the following structural formula (2) was used as the charge transport material. When the work function of this organic laminated type photoreceptor was similarly measured, it was 5.50 eV.

[0118]

[Chemical 2]

(Production Example of Developing Roller 11) Developing Roller 1
1 is nickel plated (thickness 23 μm) on the surface of an aluminum pipe with a diameter of 18 mm, and the surface roughness (Ra) is 4 μm.
Got the surface of. A part of the surface of the developing roller 11 was cut out, and the work function was measured in the same manner.
It was V.

(Manufacturing Example of Toner Control Blade) The toner control blade 7 is a SUS plate having a thickness of 80 μm and a thickness of 1.5.
A mm-sized conductive urethane rubber chip was attached by a conductive adhesive, and the work function of the urethane portion was set to about 5 eV.

(Production Example of Transfer Medium of Intermediate Transfer Device) A polyethylene terephthalate resin film having a thickness of 130 μm formed by depositing aluminum on the intermediate conductive layer which is the conductive layer of the intermediate transfer belt 36 which is the transfer medium of the intermediate transfer device 30. On top, a uniform dispersion of 30 parts by weight of vinyl chloride-vinyl acetate copolymer, 10 parts by weight of conductive carbon black, and 70 parts by weight of methyl alcohol was applied by roll coating to a thickness of 20 μm. It was formed by industrial drying.

Next, a transfer layer, which is a resistance layer, was formed on the intermediate conductive layer: 55 parts by weight of nonionic water-based urethane resin (solid content: 62% by weight) Polytetrafluoroethylene emulsion resin (60% by weight of solid content) ) 11.6 parts by weight, conductive tin oxide 25 parts by weight, polytetrafluoroethylene fine particles (max particle system of 0.3 μm or less) 34 parts by weight, polyethylene emulsion (solid content 35% by weight) 5 parts by weight, ion-exchanged water 20 A coating solution obtained by mixing and dispersing parts by weight of the composition is similarly coated and dried by a roll coating method to a thickness of 10 μm,
Formed.

Then, this coated sheet was made to have a length of 540 mm.
The intermediate transfer belt 36 was produced by cutting the sheet into pieces, aligning the ends with the coated surface facing upward, and performing ultrasonic welding. The volume resistance of the intermediate transfer belt 36 is 2.5 × 10 ¹⁰ Ω · c.
It was m. The work function was 5.37 eV, and the normalized photoelectron yield was 6.90.

(Preparation Example of Fixing Device) The fixing device 60 is composed of two pressure rollers (about 38 k) including a heater roller and a press roller.
gf load). The heater roller has a built-in halogen lamp 600w, silicone rubber 2.5mm (60mm
° JISA) and PFA with a thickness of 50μm on φ4
Formed to 0. Also, the press roller is a halogen lamp 3.
Built-in 00w, silicone rubber 2.5mm (60 ° JI
A film of PFA having a thickness of 50 μm was formed on the surface of (SA) to form φ40. The fixing temperature is set to 190 ° C.

The outline of the operation of the full-color printer configured as described above is as follows. (i) When a print command signal (image forming signal) from a host computer or the like (not shown) (personal computer or the like) is input to the control unit 90 of the image forming apparatus, the photoconductor 14
0, each roller 11 of the developing device 10, and the intermediate transfer belt 36 are rotationally driven.

(Ii) The outer peripheral surface of the photoconductor 140 is uniformly charged by the charging roller 160. (iii) The exposure unit 40 performs selective exposure L1 according to the image information of the first color (for example, yellow) on the outer peripheral surface of the uniformly charged photoconductor 140 to form an electrostatic latent image for yellow. To be done.

(Iv) In the photoconductor 140, only the developing roller of the first color developing device 10Y for yellow, for example, is set with a predetermined developing gap L with respect to the photoconductor 140 or the photoconductor 140 is set. And the electrostatic latent image is developed by non-contact development or contact development, and a yellow toner image of the first color is formed on the photoconductor 140. (v) A primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the intermediate transfer belt 36, and the toner image formed on the photoconductor 140 is transferred onto the intermediate transfer belt 36 at the primary transfer portion T1. It At this time, the secondary transfer roller 3
8 and the belt cleaner 39 are separated from the intermediate transfer belt 36.

(Vi) After the toner remaining on the photoconductor 140 is removed by the cleaning unit 170, the photoconductor 140 is neutralized by the neutralizing light L2 from the removing unit 41. (vii) The above operations (ii) to (vi) are repeated as necessary. That is, the second color, the third color, and the fourth color are repeated according to the print command signal, and toner images according to the content of the print command signal are formed on the intermediate transfer belt 36 in an overlapping manner.

(Viii) Paper feeding device 50 at a predetermined timing
The sheet S is fed from, and immediately before or after the leading edge of the sheet S reaches the secondary transfer portion T2 (in short, at a timing when the toner image on the intermediate transfer belt 36 is transferred to a desired position on the sheet S). The secondary transfer roller 38 transfers the toner image on the intermediate transfer belt 36 (basically a full-color image in which toner images of four colors are superimposed) onto the sheet S. Further, the belt cleaner 39 contacts the intermediate transfer belt 36, and the toner remaining on the intermediate transfer belt 36 after the secondary transfer is removed.

(Ix) The toner image on the sheet S is fixed by the sheet S passing through the fixing device 60, and then,
The sheet S is conveyed to a predetermined position (to the sheet receiving portion 81 when the printing is not double-sided, and to the return roller 73 via the switchback path 71 or 72 when double-sided printing).

(Imaging Test and Test Results) (Imaging Test 1) Using a full color printer using the organic photoconductor 1 (OPC1) capable of the non-contact development process shown in FIG. Non-contact development method (image forming condition: dark potential −60 of organic photoreceptor 1 −60 μm)
0 V, bright potential of organic photoreceptor 1-80 V, DC developing bias -300 V, AC developing bias 1.35 kV, AC frequency 2.5 kHz), and cyan developing device 10 (C) is shown in Table 4.
The toner of Example 1 of the present invention and the toners of Comparative Examples 1 and 2 shown in FIG.
I imaged it to be around 1.2. The charge characteristic amount of the cyan toner on the developing roller 11 at that time was measured with a commercially available charge amount distribution measuring device E-SPART analyzer EST-3 type manufactured by Hosokawa Micron Corporation. Further, the fog toner on the organic photoconductor 1 at that time was measured by the tape transfer method, and the reverse transfer toner transferred from the transfer belt 36 onto the organic photoconductor 1 at the time of printing the second color was also measured by the tape transfer method. . In addition, the tape transfer method is to attach a Sumitomo 3M mending tape onto the toner, transfer the fog toner and reverse transfer toner onto the tape, and then attach it onto a blank sheet of paper and measure the density with a reflection densitometer from the tape. The tape density is subtracted from the measured value to define the fog density and reverse transfer density. The measurement results are shown in Table 5.

[0132]

[Table 5]

As is clear from Table 5, when the hydrophobic positively charged silica 16 having a large particle size (particle size: about 30 nm) is added, the positively charged silica 16 having a large particle size is not added. It was shown that the charge amount was higher than that of the toner, and that the fog toner and the reverse transfer toner were decreased. Also,
The toners of Comparative Examples 1 and 2 to which the hydrophobic positively chargeable silica having a small particle diameter (particle diameter: about 12 nm) was added, on the contrary, reduced the charge amount and increased the fog toner concentration and the reverse transfer toner concentration. Was shown. Therefore, even in the case of positively chargeable silica, the positively chargeable silica 16 having a large particle size has a higher charge amount than the positively chargeable silica having a small particle size, and is more effective in preventing fog and reverse transfer. It was

(Image Forming Test 2) Electron micrographs of the toner of Example 4 of the present invention and the toners of Comparative Examples 7 and 8 were taken and shown in FIGS. 7, 8 and 9, respectively. As is clear from the electron micrographs shown in FIGS. 7 to 9, 0.2% of the hydrophobic positively charged silica 16 having a large particle size was used.
The toner of Example 4 added by weight% shows a state in which the external additive is firmly adhered to the surface of the toner mother particles 8a, but, on the contrary, the hydrophobic positive charging property of the small particle size is exhibited. In both the toner of Comparative Example 7 containing silica and the toner of Comparative Example 8 containing no positively chargeable silica, the external additive was slightly floated from the surface of the toner mother particles 8a and was present in a state of weak adhesion. It is in the state of being.

Therefore, the negatively charged toner 8 of Example 4 of the present invention can sufficiently and effectively exhibit the above-mentioned function of the external additive firmly adhered to the surface of the toner mother particles 8a. It was found that in each of the negatively charged toners of Examples 7 and 8, the surface of the toner mother particles 8a was easily liberated, and the above-mentioned function of the external additive could not be sufficiently exhibited. That is,
If the adhesiveness of the external additive to the toner mother particles 8a is weak, the chargeability of the toner is lowered, and the toner is scattered from the surface of the developing roller 11 due to continuous printing. Actually, each toner is set in the cyan developing device 10 (C) of the color printer shown in FIG.
Toner scattering around 1 was visually compared, but almost no toner scattering was observed in Example 4 of the present invention.
Scattering of each toner of Comparative Examples 7 and 8 was confirmed. A magenta toner, which is the toner of Example 5 of the present invention, which has been subjected to the same external additive treatment as that of the toner of Example 4 was used to perform a printing test on 1000 sheets in the same manner. The scattering could not be visually confirmed.

(Imaging Test 3) The toner of Example 1 was added with a large particle size of positively chargeable silica 16 in an amount of 0 to 0.6% by weight.
The image formation was performed in the same manner as in the image formation test 1 after the above. The results are shown in Table 6.

[0137]

[Table 6]

As is apparent from Table 6, when the addition amount of the positively chargeable silica 16 is 0.6% or more, the charge amount decreases, the solid image density also decreases, and the reverse transfer toner amount tends to increase. I found out that Therefore,
The addition amount of the positively chargeable silica 16 is preferably 30% or less with respect to the total amount of the negatively chargeable silicas 13 and 14 because good results can be obtained.

(Image Forming Test 4) Using the toner of Example 3 of the present invention, an image was formed in the same manner as in the image forming test 1 described above. As a result of image formation, the toner of Example 3 has a charge amount of −20 μc / g, a solid average image density of 1.350, a fog toner OD value of almost 0, and a reverse transfer toner OD as compared with the toner of Example 1. The values also showed almost 0, respectively, and it was found that a print quality with very high image quality was obtained with substantially no generation of fog toner and reverse transfer toner. This is positively charged silica 16
In addition to this, it is considered that by further adding rutile-anatase type titanium oxide having a work function larger than that, the negative overcharge property is suppressed and at the same time, the generation of the positive polarity toner is suppressed. .

(Image Forming Test 5) Cyan toner which is the toner of Example 4, magenta toner which is the toner of Example 5,
A combination of the four-color toner of the yellow toner that is the toner of Example 6 and the black toner that is the toner of Example 7 and the organic photoconductor 1 (OPC2) given by the above structural formula (2) is shown in FIG. A full-color image was formed by the contact development method using a full-color printer capable of the contact development method shown. This image was created at 10 ℃ in the environmental test room.
RH15% low humidity at low temperature, RH60% at room temperature 23 ° C
Under the conditions of the normal humidity and the high temperature of 35 ° C. and the high humidity of RH of 65%, full-color printing with a duty of 20% was performed for each color of 5000 sheets in total. When the quality of the image formed was checked, it was possible to obtain stable image quality without toner scattering around the developing section.

(Image Forming Test 6) The toner of Example 2 and Comparative Examples 4 to 6 were used to form an image by the contact developing method of Image Forming Test 5, and then the fixing property was obtained using the fixing device 60 described below. A comparison was made. The fixing device 60 is a φ40 heater roller {built-in halogen lamp 600w, silicone rubber 2.5 mm (60 ° J
ISA) with a PFA film thickness of 50 μm} and a φ40 press roller {built-in halogen lamp 300w, silicon rubber 2.5 mm (60 ° JISA) with a PFA thickness of 5
Fixing was performed at a set temperature of 190 ° C. using two pressure rollers (with a load of about 38 kgf) of 0 μm film thickness}, and the fixing properties between the respective toners were compared. A 200 g weight is placed on a cotton cloth, and the solid image is rubbed 50 times on the solid image, the solid image density before and after the rubbing is measured, and the fixing property of the toner is converted into a retention ratio (fixing ratio) (%) to evaluate the fixing property. Was used as an index. The results are shown in Table 7.
Shown in.

[0142]

[Table 7]

As is apparent from Table 7, the toner of Example 2 showed a retention rate (fixing rate) of 95% and was comparable to the toner of Comparative Example 6 in which the amount of negatively chargeable silica used was small, but
Comparative Example 4 in which the silica amount of the small particle size silica 13 is relatively large.
And 5 showed a retention rate (fixing rate) of 90%. From this, it was found that even if the same amount of the fluidizing agent was added, the use of the positively chargeable silica 16 having a large particle size hardly deteriorates the fixability. A similar fixing test was conducted by changing the average primary particle diameter of the negatively chargeable silica 13 having a small particle diameter to about 12 nm and about 16 nm, but this tendency was not reversed. The larger average primary particle size did not lower the fixability.

(Image Forming Test 7) Cyan toner which is the toner of Example 4, magenta toner which is the toner of Example 5,
A four-color toner, a yellow toner that is the toner of Example 6 and a black toner that is the toner of Example 7, and the organic photoconductor 1 (OPC1) given by the above structural formula (1).
6 is used in combination, a full-color image of the non-contact development method is set by using a full-color printer of the intermediate transfer method, which is set to enable the non-contact development method and includes the intermediate transfer belt 36. went.

This image was formed with a DC developing bias of -200 V, a frequency of 2.5 kHz and a PP voltage of 1450.
AC of V is superposed, the gap L between the developing roller 11 and the organic photoconductor 1 is set to 210 μm (adjusted by using a gap roller), and a character original corresponding to 5% color original for each color is set to 1
Printing was performed by continuously printing 0000 sheets.

The amount of cleaning toner on the organic photoconductor 1 was measured for four colors and found to be about 95 g, which can be reduced to about half the planned cleaning toner capacity of the photoconductor portion. It was As a result, the above-mentioned 4
Each color toner, the organic photoreceptor 1 (OPC1) described above,
By combining with the above-mentioned full-color printer of the non-contact development type and the intermediate transfer type, the reverse transfer toner and the fog toner can be suppressed more effectively.

[0147]

As is apparent from the above description, according to the negatively charged toner of the present invention and the image forming apparatus using the same, the toner mother particles to which at least the hydrophobic negatively chargeable external additive is added are added. By adding a hydrophobic positively-charged external additive having a positively-charged property so that the positively-charged external additive can exert the function of the microcarrier, the rise of the charging of the toner mother particles can be accelerated. The reverse transfer toner and fogging can be effectively suppressed.

Further, according to the negatively charged toner toner of the present invention, the hydrophobic negatively charged silica is used together with the hydrophobic rutile-anatase type titanium oxide, whereby the toner mother particles of the hydrophobic rutile-anatase type titanium oxide are contained. It is possible to make more effective use of the characteristics that are difficult to be buried in the battery and the charge adjusting function. Therefore, the unique properties of the negative charge performance and fluidity of the hydrophobic negatively chargeable silica and the unique property of the relatively low resistance and negative overcharge prevention property of the hydrophobic rutile-anatase type titanium oxide are A synergistic function can be imparted to the toner mother particles. This allows
Since it is possible to prevent the fluidity of the negatively charged toner from being reduced and to prevent negative overcharge, it is possible to obtain a better negative charging characteristic, and as a result, it is possible to more effectively suppress the occurrence of the reverse transfer toner and fogging.

Moreover, by using two kinds of hydrophobic negatively-charged silica particles having different average primary particle diameters, the surface of the toner mother particles is made to have a hydrophobic negatively-charged silica, a hydrophobic positively-charged silica, and a hydrophobic positively-charged silica. Since it is uniformly covered with rutile anatase type titanium oxide, the negative charge of the negatively charged toner can be stabilized for a longer period of time, and more stable image quality in continuous printing can be provided.
In particular, by adding hydrophobic negatively-charged silica having at least an average primary particle size of smaller than the total amount of the hydrophobic positively-charged silica and the hydrophobic rutile-anatase type titanium oxide, the negatively-charged toner is negatively charged. Can be stabilized for a longer period of time. Therefore, the fogging of the non-image area can be further suppressed, the transfer efficiency can be further improved, and the generation of the reverse transfer toner can be suppressed more effectively.

Further, when the positively chargeable silica as the fluidizing agent is added, the positively chargeable silica having a large particle size is used, so that the fixing is performed as compared with the case where the positively chargeable silica having a small particle size is used. It is possible to prevent deterioration of sex.

Further, regardless of whether it is a pulverized toner or a polymerized toner, hydrophobic negatively chargeable silica having two kinds of particle sizes, large and small,
By using hydrophobic positively charged silica and hydrophobic rutile anatase type titanium oxide together, the amount of hydrophobic negatively charged silica can be reduced, so that the reverse transfer toner, the fluctuation of the image density, and the fog of the non-image area are prevented. It can be suppressed more effectively.

Since the generation of reverse transfer toner can be suppressed more effectively, when the negatively charged toner of the present invention is used as a full color toner, the image density can be kept more uniform for a long period of time. Thereby, a high-quality full-color image can be obtained for a long time.

Furthermore, according to the method for producing a negatively charged toner of the present invention, the hydrophobic rutile-anatase type titanium oxide is adhered to the hydrophobic negatively charged silica attached to the toner mother particles on the surface of the toner mother particles. Since the positively chargeable silica adheres directly to the surface of the toner mother particles in addition to the reliable adhesion, the reverse transfer toner, the fog toner, and the negatively charged toner of the present invention capable of effectively suppressing the fluctuation of the image density. Will be reliably manufactured.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of an embodiment of a negatively charged toner according to the present invention.

FIG. 2 is an explanatory diagram for explaining the behavior of the negatively charged toner of the example shown in FIG.

FIG. 3 is a diagram schematically showing an example of a non-contact development process of an image forming apparatus in which the negatively charged toner according to the present invention is used.

FIG. 4 is a diagram schematically showing an example of a contact developing process of an image forming apparatus in which the negatively charged toner according to the present invention is used.

5 is a diagram showing an organic laminate type photoreceptor of the image forming apparatus shown in FIGS. 3 and 4. FIG.

FIG. 6 shows an example of an image forming apparatus using an intermediate transfer medium in a non-contact development process system using a negatively charged toner of the present invention, and a non-contact development used in an image forming test with the negatively charged toner of the present invention. It is a figure which shows an example of a full cycle printer of a 4-cycle system by a process and a contact development process.

FIG. 7 is a diagram showing an electron micrograph of a negatively charged toner of Example 4 of the present invention.

FIG. 8 is a diagram showing an electron micrograph of a negatively charged toner of Comparative Example 7.

9 is a diagram showing an electron micrograph of a negatively charged toner of Comparative Example 8. FIG.

[Explanation of symbols]

1, 140 ... Organic photoconductor, 2 ... Corona charger, 3 ... Exposure, 4 ... Cleaning blade, 5 ... Transfer roller, 6 ...
Supply roller, 7 ... Regulating blade, 8 ... Negatively charged toner (one-component non-magnetic toner), 8a ... Toner mother particles, 9 ... Transfer material or transfer medium, 10 ... Developing device, 11 ... Developing roller, 1
2 ... external additive, 13 ... small particle size of the hydrophobic negatively chargeable silica (SiO _2), 14 ... of the large particle size hydrophobic negatively chargeable silica (SiO _2), 15 ... hydrophobic rutile anatase Titanium (TiO ₂ ), 16 ... Hydrophobic positively charged silica (SiO ₂ ) with large particle size, L ... Development gap

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 7, 2001 (2001.12.
7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

The average primary particle diameter of the hydrophobic negatively chargeable silica 13 having a small particle diameter is 20 nm or less, preferably 7 to 16 n.
m (this notation means 7 nm to 16 nm; the same applies to other units), and the average primary particle diameter of the hydrophobic negatively chargeable silica 14 having a large particle diameter is 30 nm or more, preferably Is set to 40 to 50 nm. Furthermore, in the hydrophobic rutile-anatase type titanium oxide 15, rutile type titanium oxide and anatase type titanium oxide are used in a predetermined mixed crystal ratio.
It can be manufactured by the manufacturing method disclosed in Japanese Patent No. 8534. This hydrophobic rutile-anatase type titanium oxide 15 has a spindle shape and its major axis diameter is 0.0
It is 2 to 0.10 μm, and the axial diameter ratio of the major axis and the minor axis is set to 2 to 8. Further, the average primary particle size of the hydrophobic positively charged silica 16 is the same as or substantially the same as the particle size of the hydrophobic negatively charged silica 14 having the large particle size described above, and is 30 nm or more, preferably 40 to 50 nm. Is set to.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/01 114 G03G 9/08 384 15/16 381 361 F term (reference) 2H005 AA08 AA21 AB05 AB06 CB07 CB13 DA02 DA03 EA05 EA07 2H030 AA03 AD01 BB23 BB34 BB42 2H200 FA16 GA16 GA23 GA44 GA47 GA52 GA54 GA57 GB02 GB12 GB25 HA12 HB03 JA02 JA08 JB10 JC04 JC13 JC15 LC03 MA04 MA17 MA20

Claims (12)

[Claims] 1. A negatively charged toner comprising at least a negatively chargeable external additive having a negatively chargeable property with respect to the toner mother particles, which has a positively chargeable property with respect to the toner mother particles and has a negatively chargeable property. A negatively charged toner, to which a positively chargeable external additive having a work function larger than that of the additive is added. 2. The total amount of all external additives including the positively chargeable external additive is set to 0.5% by weight to 4.0% or less based on the weight of the toner mother particles. The negatively charged toner according to claim 1. 3. The negatively charged external additive is hydrophobic negatively charged silica, and the positively charged external additive is hydrophobic positively charged silica. The negatively charged toner described. 4. The hydrophobic negatively chargeable silica is composed of negatively chargeable silica having an average primary particle diameter of a small particle size and negatively chargeable silica having an average primary particle size larger than the small particle size. 4. The negatively charged toner according to claim 3, wherein the hydrophobic positively charged silica has an average primary particle size which is the same as or substantially the same as the negatively charged silica having the large particle size. 5. A hydrophobic rutile-anatase type titanium oxide having a work function substantially the same as that of the toner mother particles or a work function larger than that of the toner mother particles is added, and the hydrophobic negative electrification property is added. The silica is added in an amount larger than the total amount of the hydrophobic positively charged silica and the hydrophobic rutile-anatase type titanium oxide.
Alternatively, the negatively charged toner according to item 4. 6. The negative according to claim 4, wherein the amount of the hydrophobic positively chargeable silica is set to 30% by weight or less of the total weight of the hydrophobic negatively chargeable silica. Charged toner. 7. A pulverized toner using the toner mother particles produced by a pulverizing method or a polymerized toner using the toner mother particles produced by a polymerizing method. 1. A one-component non-magnetic toner according to any one of 1. 8. The negatively charged toner according to claim 1, which has a circularity of 0.91 or more. 9. The negatively charged toner according to claim 1, wherein the number-based 50% diameter (D ₅₀ ) is 9 μm or less. 10. The method for producing a negatively charged toner according to claim 5, wherein the toner mother particles and the negatively chargeable silica are first mixed, and then the mixture is mixed with the hydrophobic rutile-anatase type oxidation. A method for producing a negatively-charged toner, characterized in that the negatively-charged toner is produced by adding and mixing titanium, and further mixing the positively-chargeable silica. 11. An intermediate transfer type full-color image forming apparatus using an intermediate transfer medium, wherein the negatively charged toner according to claim 1 is used for each of the toners of cyan, magenta, yellow, and black. Image forming apparatus. 12. The image forming apparatus according to claim 11, wherein the intermediate transfer medium is an intermediate transfer medium including a belt.