JP2007079309A - Toner, image forming method, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for electrostatic latent image development which causes no scumming and with which superior image performance can be obtained by carrying out efficient and uniform frictional electrostatic charging between a developing roller and a regulating blade in a developing unit. <P>SOLUTION: Toner obtained by externally adding inorganic particulate to a toner base body composed of binder resin and a coloring agent is characterized in that the inorganic particulate are compound oxides and have a 1 to 9 specific dielectric constant and a 5E-5 to 1E-3 dielectric tangent at a frequency of 1MHz, sticking strength of the inorganic particulate to the toner base body is 50 to 80%, and dispersion diameter distribution of the inorganic particulate on a toner surface is 100 to 500 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is suitable for an electrostatic latent image developing toner, particularly a developing device that forms a thin layer by pressing a developing roller and a regulating blade, and further includes a means for contacting and charging a latent image holding member. The present invention relates to a toner and an image forming method. The present invention further relates to a toner for developing an electrostatic latent image used in a copying machine, a printer, or the like applying electrophotographic technology, and an image forming method using the same, and more particularly, fogging on paper due to poor charging of the toner, image density, and the like. The present invention relates to an electrostatic latent image developing toner and an image forming method capable of suppressing unevenness and obtaining excellent image stability.

  Conventionally, in electrophotography, the electrostatic latent image formed by charging and exposing the surface of a photoreceptor is developed with a colored toner to form a toner image, and the toner image is transferred to a transfer medium such as transfer paper. This is fixed with a heat roll or the like to form an image.

  Dry development methods employed in electrophotography, electrostatic recording, and the like include a method using a two-component developer composed of a toner and a carrier and a method using a one-component developer not containing a carrier. The former method provides a relatively stable and good image, but it is difficult to obtain a constant quality image over a long period of time because carrier deterioration and a change in the mixing ratio of toner and carrier are likely to occur. In addition, there are difficulties in maintaining and managing the apparatus and making it compact. In view of this, a method using the latter one-component developer which does not have such drawbacks has been attracting attention.

  By the way, in this system, means for visualizing the electrostatic latent image formed on the latent image carrier by the toner (developer) usually conveyed by at least one toner conveying member and the conveyed toner. In this case, a means for regulating the toner layer thickness is opposed to the toner conveying member, and the toner is charged when the toner passes through the regulating means. Various methods have been proposed for the toner layer thickness regulating means (toner layer thickness regulating means) placed on the toner conveying member. As a typical example, a regulating blade is used, and this blade is opposed to the toner conveying member. Thus, the toner conveyed on the surface of the toner conveying member is pressed by a pressing member (regulating blade) to control the toner layer thickness. There is also a type that obtains the same effect by contacting a roller instead of a blade.

  There are two methods for charging the surface of the photoconductor: non-contact wire discharge, and contact injection, micro discharge, etc. Therefore, the contact charging method is preferably used.

  In the developing process, in the toner layer formed on the surface of the developing sleeve by the developer layer thickness regulating member, the toner present in the vicinity of the developing sleeve surface in the toner layer has a very high charge. Since the toner is strongly attracted to the surface of the sleeve by the reflection force and becomes immobile on the surface of the developing sleeve, the toner does not move from the developing sleeve to the latent image on the latent image carrier, and a charge-up phenomenon is likely to occur. Become. In particular, the charge-up phenomenon is likely to occur under low humidity.

  When such a charge-up phenomenon occurs, the toner on the upper layer of the toner layer formed on the developing sleeve is less likely to be charged, so the charge amount of the toner is reduced. It tends to cause toner leakage and toner scattering. In order to eliminate such a phenomenon, it is necessary to have a configuration in which the charge amount of the toner in the toner layer formed on the developing sleeve can be controlled as uniformly as possible.

In order to solve such problems, various electrical characteristics of the toner have been improved. (For example, refer to Patent Documents 1 to 8.) For example, the relative permittivity of the metal oxide contained in the toner is specified, but the dielectric loss tangent is not specified, so that sufficient charge rising property cannot be obtained. (Patent Document 1), CCA is a polymer-type CCA, but generally, the polymer-type dielectric loss tangent has a high value and the charge rising property is low (Patent Document 2). ), The toner is for a two-component developer, and defines the relative dielectric constant and dielectric loss tangent of the toner (Patent Document 3), or defines the relative dielectric constant and dielectric loss tangent of the toner ( Patent Document 4), which defines the dielectric loss tangent of toner at a high frequency (Patent Documents 5, 6, and 7), and which defines the relative dielectric constant and dielectric loss tangent of toner (Patent Document 8). , Relating to toner Improved electrical properties have been made, it is not yet sufficient, the improvement of the electrical characteristics of the additives as a charge auxiliary agent for satisfying the rapid charge rising property is required. There is also a need for improvements that are particularly suitable for development systems that use a one-component developer.
JP 2005-157318 A Japanese Patent No. 2972987 Japanese Patent No. 2769317 JP 2000-003066 A JP 2004-78206 A JP 2004-29156 A JP 2001-142258 A Patent No. 3091130 JP 11-327200 A

  Accordingly, the present invention has been made in view of the above, and an object of the present invention is to develop a latent electrostatic image developing toner for use in a copying machine, a printer or the like to which an electrophotographic technology is applied, an image forming method using the same, With respect to the image forming apparatus and the process cartridge, in particular, the frictional charging between the developing roller and the regulating blade in the developing device is performed efficiently and uniformly, so that the background is not stained and excellent static image performance can be obtained. A toner for developing a latent charge image, an image forming method, an image forming apparatus, and a process cartridge are provided. In particular, the present invention provides a toner for developing an electrostatic latent image that is suitable for a developing method using a one-component developer.

  Therefore, as a result of repeated studies by the inventor, the optimum ratio as a charging aid for raising the charge to a desired charge level for development within a moment passing through the regulating means and holding the charge. It has been found that there are regions of dielectric constant, dielectric loss tangent, adhesion strength and dispersion diameter.

That is, as described in claim 1, the above object is achieved by a toner in which inorganic fine particles are externally added to a toner base composed of at least a binder resin and a colorant.
The inorganic fine particles have a relative dielectric constant and dielectric loss tangent at a frequency of 1 MHz of 1 to 9, 5E-5 to 1E-3, respectively, and the adhesion strength of the inorganic fine particles to the toner base is 50 to 80%. This is achieved by the toner for developing an electrostatic latent image, wherein the dispersion diameter distribution of the inorganic fine particles is 100 to 500 nm.

  According to the first aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the inorganic fine particles are a composite oxide represented by the following general formula.
[M1] aSibOc
(In the formula, M1 represents a metal element selected from Sr, Mg, Zn, Co, Mn and Ce, a and b represent an integer of 1 to 9, and c represents an integer of 3 to 9)
According to the second aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

  The invention according to claim 3 is the invention according to claim 1 or 2, characterized in that the inorganic fine particles are magnesium silicate in which M1 of the general formula is represented by Mg.

  According to the third aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the inorganic fine particles are forsterite.

  According to the fourth aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the content quantified by the magnesium element when the wavelength dispersive X-ray fluorescence analyzer is used is based on the toner weight. 0.1 to 2.5%.

  According to the fifth aspect of the present invention, the charge promoting effect of the inorganic fine particles is good, and it can be efficiently fixed to the toner base.

  The invention according to claim 6 is the invention according to claim 1, wherein the inorganic fine particles are alumina or aluminum nitride.

  According to the sixth aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

  The invention according to claim 7 is the invention according to claim 6, wherein the content determined by the aluminum element by the wavelength dispersive X-ray fluorescence analyzer is 0.1 to 2.5% with respect to the toner weight. It is characterized by that.

  According to the seventh aspect of the invention, the effect of promoting charging of the inorganic fine particles is good, and the inorganic fine particles can be efficiently fixed to the toner base.

  The invention according to claim 8 is the invention according to claim 1, wherein the inorganic fine particles are cordierite.

  According to the eighth aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the volume average diameter is 5 to 10 μm.

  According to the ninth aspect of the invention, it is possible to obtain an electrophotographic image having excellent image quality with a sufficient image density without causing background contamination due to poor charging.

  The invention according to a tenth aspect is the invention according to any one of the first to ninth aspects, wherein the electrostatic charge latent image developing toner is a non-magnetic one-component developing toner.

  According to the tenth aspect of the present invention, even in a developing method using a one-component developer, an electrophotographic image having excellent image quality can be obtained with a sufficient image density without causing background contamination due to defective charging. .

  The invention according to claim 11 is achieved by a developer using the toner for developing an electrostatic latent image according to any one of claims 1 to 10.

  According to the eleventh aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to charging failure.

The invention according to claim 12 is at least a rotatable image carrier;
A contact charging member disposed in contact with the image carrier and charging the image carrier to a predetermined potential;
11. An image forming method using a rotating toner conveying member and a developing device having a toner supply member that supplies toner to the conveying member, wherein the toner is a static device according to any one of claims 1 to 10. This is achieved by an image forming method characterized by being a toner for developing a latent charge image.

  According to the twelfth aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to poor charging.

  A thirteenth aspect of the present invention is an image forming apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transfer unit, a cleaning unit, and a photoreceptor, and uses the image forming method according to the twelfth aspect. This is achieved by an image forming apparatus.

  According to the thirteenth aspect of the present invention, an excellent photographic image can be obtained with a sufficient image density without causing background contamination due to poor charging.

The invention according to claim 14 includes at least a rotatable image carrier,
A contact charging member disposed in contact with the image carrier and charging the image carrier to a predetermined potential;
11. A process cartridge provided with a developing device having a rotating toner conveying member and a toner supply member for supplying toner to the conveying member, wherein the toner is a detachable process cartridge, wherein the toner is any one of claims 1 to 10. An electrostatic charge latent image developing toner according to claim 1 is achieved.

  According to the fourteenth aspect of the present invention, it is possible to obtain an electrophotographic image having an excellent image quality with a sufficient image density without causing background contamination due to poor charging.

  Therefore, according to the present invention, an electrophotographic image with excellent image quality can be obtained with a sufficient image density without causing background contamination due to defective charging.

  Hereinafter, embodiments of the present invention will be described.

  Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims of the present invention.

  The toner particles for developing an electrostatic latent image of the present invention are such that the inorganic fine particles contained in the toner have a relative dielectric constant and a dielectric loss tangent of 1 to 9, 5E-5 to 1E-3 at a frequency of 1 MHz, respectively, and A toner for developing an electrostatic latent image, wherein the adhesion strength of the inorganic fine particles is 50 to 80%, and the dispersion diameter distribution of the inorganic fine particles on the toner surface is 100 to 500 nm.

  If the relative dielectric constant is less than 1, the charge level is low, and therefore background contamination due to poor charging tends to occur. On the other hand, if the relative dielectric constant is higher than 9, the charge level becomes high, so that developability is lowered and sufficient image density cannot be obtained.

  There is no problem if the dielectric loss tangent is smaller than 5E-5, but it is not substantially smaller than this value. Further, if the dielectric loss tangent is larger than 1E-3, the charge rising property is deteriorated, so that the background contamination due to poor charging is likely to occur.

  If the adhesion strength of the inorganic fine particles is less than 50%, the amount of the third component present is large, so that it moves like a charged toner, resulting in image noise. There is no problem even if it is larger than 80%, but it is not substantially larger than this value.

  The dispersion diameter is fixed to the toner and needs a certain size in order to satisfy the function as a charge aid. If it is 500 nm or more, it is difficult to be immobilized on the toner base, and if it is 100 nm or less, it cannot function sufficiently as a charge aid.

  For the above reasons, the optimum relative dielectric constant, dielectric loss tangent, and adhesion strength as a charging aid for raising the charge to a desired charge level for development and holding the charge within a moment of passing through the regulating means There is a region of dispersion diameter.

  In the present invention, inorganic fine particle treatment may be performed on the toner surface.

  The added amount of the inorganic fine particles is suitably 1 to 5 parts by mass, preferably 1.5 to 3.5 parts by mass with respect to 100 parts by mass of the toner base. If the amount is less than 1 part by mass, the fluidity, transferability and heat-resistant storage stability are greatly reduced. If the amount is more than 5 parts, fogging, developability and fixing separation properties are deteriorated.

  The toner base that can be used in the present invention usually contains a binder resin, a colorant, and other additives. In this toner base, (1) a colorant, a charge control agent, a release agent and the like are melt-mixed and uniformly dispersed in a thermoplastic resin as a binder resin component to obtain a composition. A toner base obtained by pulverizing and classifying the product, and (2) a polymerization initiator in which a colorant, a charge control agent, a release agent and the like are dissolved or suspended in a polymerizable monomer which is a binder resin raw material. A toner base obtained by dispersing in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to start suspension polymerization, and filtering, washing, dehydrating and drying after completion of the polymerization, (3) The primary particles of the binder resin containing a polar group obtained by emulsion polymerization are aggregated by adding a colorant and a charge control agent to form secondary particles, and the temperature is higher than the glass transition temperature of the binder resin. The particles that were agitated and associated with the (4) Using a hydrophilic group-containing resin as a binder resin, adding a colorant or the like to the resin and dissolving it in an organic solvent, neutralizing the resin, phase-inverting, and then drying. Examples thereof include a phase inversion emulsification method toner base material for obtaining colored particles, and any of them can be used.

  In this toner base, (1) a colorant, a charge control agent, a release agent and the like are melt-mixed and uniformly dispersed in a thermoplastic resin as a binder resin component to obtain a composition. A toner base obtained by pulverizing and classifying the product, and (2) a polymerization initiator in which a colorant, a charge control agent, a release agent and the like are dissolved or suspended in a polymerizable monomer which is a binder resin raw material. A toner base obtained by dispersing in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to start suspension polymerization, and filtering, washing, dehydrating and drying after completion of the polymerization, (3) The primary particles of the binder resin containing a polar group obtained by emulsion polymerization are aggregated by adding a colorant and a charge control agent to form secondary particles, and the temperature is higher than the glass transition temperature of the binder resin. The particles that were agitated and associated with the (4) Using a hydrophilic group-containing resin as a binder resin, adding a colorant or the like to the resin and dissolving it in an organic solvent, neutralizing the resin, phase-inverting, and then drying. Examples thereof include a phase inversion emulsification method toner base material for obtaining colored particles, and any of them can be used.

  Although the present invention will be described using a pulverized toner, the present invention is not limited to this.

(Binder resin)
The type of binder resin is not particularly limited, and binder resins known in the field of full-color toners such as polyester resins, (meth) acrylic resins, styrene- (meth) acrylic copolymer resins, epoxy resins, COC (Cyclic olefin resin (for example, TOPAS-COC (manufactured by Ticona))) or the like, but from the viewpoint of stress resistance in the developing device, it is preferable to use a polyester resin.

  As the polyester resin preferably used in the present invention, a polyester resin obtained by polycondensation of a polyhydric alcohol component and a polyvalent carboxylic acid component can be used. Examples of the dihydric alcohol component among the polyhydric alcohol components include polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2- Bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane Bisphenol A alkylene oxide adducts such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol , Polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A, and the like. Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol. 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Is mentioned.

  Among the polyvalent carboxylic acid components, examples of the divalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and succinic acid. , Adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, isooctenyl succinic acid, n-octyl succinic acid , Isooctyl succinic acid, anhydrides or lower alkyl esters of these acids.

  Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2 , 4-Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4- Examples include cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, emporic trimer acid, anhydrides of these acids, and lower alkyl esters.

  In the present invention, as a polyester resin, a polyester resin raw material monomer, a vinyl resin raw material monomer, and a mixture of monomers that react with both resin raw material monomers are used to obtain a polyester resin in the same container. A resin obtained by performing a condensation polymerization reaction and a radical polymerization reaction for obtaining a vinyl resin in parallel (hereinafter, simply referred to as “vinyl polyester resin”) can also be suitably used. In addition, the monomer which reacts with the raw material monomers of both resins is, in other words, a monomer that can be used for both the condensation polymerization reaction and the radical polymerization reaction. That is, it is a monomer having a carboxy group that can undergo a condensation polymerization reaction and a vinyl group that can undergo a radical polymerization reaction, and examples thereof include fumaric acid, maleic acid, acrylic acid, and methacrylic acid.

  Examples of the raw material monomer for the polyester resin include the aforementioned polyhydric alcohol component and polyvalent carboxylic acid component. Examples of the raw material monomer for vinyl resins include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Styrene or styrene derivatives such as butylstyrene and p-chlorostyrene; Ethylene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate , Isobutyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, 3- (methyl) butyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, methacrylic acid Silyl, alkyl methacrylates such as undecyl methacrylate, dodecyl methacrylate; methyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n acrylate Acrylic alkyl esters such as pentyl, isopentyl acrylate, neopentyl acrylate, 3- (methyl) butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, etc. Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid; acrylonitrile, maleic acid ester, itaconic acid ester, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ethyl ketone, vinyl Hexyl ketone, vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether. Examples of the polymerization initiator for polymerizing the raw material monomer of the vinyl resin include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1 Azo or diazo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, benzoyl peroxide, dicumyl peroxide, And peroxide polymerization initiators such as methyl ethyl ketone peroxide, isopropyl peroxycarbonate, lauroyl peroxide, and the like.

  As the binder resin, various polyester resins as described above are preferably used. Of these, from the viewpoint of further improving the separability and offset resistance as an oilless fixing toner, It is more preferable to use a two-binder resin.

  A more preferred first binder resin is a polyester resin obtained by polycondensation of the above-mentioned polyhydric alcohol component and polyhydric carboxylic acid component, in particular, a bisphenol A alkylene oxide adduct as the polyhydric alcohol component. It is a polyester resin obtained using terephthalic acid and fumaric acid as components.

  More preferred second binder resins are vinyl polyester resins, in particular bisphenol A alkylene oxide adduct, terephthalic acid, trimellitic acid and succinic acid are used as raw material monomers for polyester resins, and styrene and butyl acrylate are used as raw material monomers for vinyl resins. It is a vinyl polyester resin obtained by using fumaric acid as a both-reactive monomer.

  In the present invention, it is preferable that a hydrocarbon wax is internally added during the synthesis of the first binder resin. In order to add the hydrocarbon wax to the first binder resin in advance, when the first binder resin is synthesized, the hydrocarbon wax is added to the monomer for synthesizing the first binder resin. What is necessary is just to synthesize | combine binder resin. For example, the polycondensation reaction may be performed in a state where a hydrocarbon wax is added to an acid monomer and an alcohol monomer constituting the polyester resin as the first binder resin. When the first binder resin is a vinyl-based polyester resin, the vinyl-based resin raw material monomer is added dropwise to the polyester resin raw-material monomer while stirring and heating the monomer while the hydrocarbon-based wax is added. The polycondensation reaction and the radical polymerization reaction may be performed.

(wax)
Generally, the lower the polarity of the wax, the better the releasability from the fixing member roller. The wax used in the present invention is a hydrocarbon wax having a low polarity.

(Hydrocarbon wax)
The hydrocarbon wax is a wax composed of only carbon atoms and hydrogen atoms, and does not contain an ester group, an alcohol group, an amide group, or the like. Specific hydrocarbon waxes include polyolefin waxes such as polyethylene, polypropylene, copolymers of ethylene and propylene, petroleum waxes such as paraffin wax and microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax. . Among these, polyethylene wax, paraffin wax, and Fischer-Tropsch wax are preferable in the present invention, and polyethylene wax and paraffin wax are more preferable.

(Melting point of wax)
The melting point of the wax in the present invention is the endothermic peak of the wax at the time of temperature rise measured by a differential scanning calorimeter (DSC), and is preferably in the range of 70 ° C to 90 ° C. If it is higher than 90 ° C., the melting of the wax in the fixing process becomes insufficient, and the separation from the fixing member cannot be ensured. On the other hand, if the temperature is lower than 70 ° C., there is a problem in storage stability such that toner particles are fused in a high temperature and high humidity environment. In order to provide a sufficient margin for fixing separation at a low temperature, the melting point of the wax is more preferably 70 ° C. to 85 ° C., further preferably 70 ° C. to 80 ° C.

(Endothermic peak of wax)
Moreover, it is preferable that the half value width of the wax endothermic peak at the time of temperature rise measured by a differential scanning calorimeter (DSC) is 7 ° C. or less. Since the melting point of the wax in the present invention is relatively low, a wax whose endothermic peak is broad, that is, melted from a low temperature range, adversely affects the storage stability of the toner.

(Wax content)
The content of the wax in the toner of the present invention is in the range of 3 to 10% by mass, preferably 4 to 8% by mass, and more preferably 4 to 6.5% by mass. If the wax content is 3% by mass or less, the amount of wax that exudes between the molten toner and the fixing member in the fixing process is insufficient, and the adhesive force between the molten toner and the fixing member does not decrease. The recording member does not leave the fixing member. On the other hand, if the wax content exceeds 10% by mass, the amount of wax exposed on the toner surface increases, and the transfer efficiency from the developing unit to the photoconductor and from the photoconductor to the recording member increases due to the deterioration of the fluidity of the toner particles. This is not preferable because not only the image quality is significantly lowered, but also the wax on the surface of the toner is detached to cause contamination of the developing member and the photosensitive member.

(Content ratio of first binder resin and second binder resin)
The content ratio of the first binder resin (including the weight of the internally added wax) and the second binder resin in the toner particles is 20/80 to 45/55, preferably 30/70 to 40/60 by weight. If the amount of the first binder resin is too small, the separability and the high temperature offset resistance are deteriorated. When there is too much 1st binder resin, glossiness and heat-resistant storage property will fall.
More preferably, the softening point of the binder resin composed of the first binder resin and the second binder resin used in the weight ratio as described above is 100 to 125 ° C, particularly 105 to 125 ° C. In the present invention, the softening point of the binder resin composed of the first binder resin and the second binder resin into which wax is internally added may be in the above range.

  The acid value of the wax-added first binder resin is preferably 5 to 50 KOHmg / g, and more preferably 10 to 40 KOHmg / g. The acid value of the second binder resin is preferably 0 to 10 KOHmg / g, and more preferably 1 to 5 KOHmg / g. In particular, when a polyester resin is used, by using a resin having such an acid value, the dispersibility of various colorants and the like can be improved, and a toner having a sufficient charge amount can be obtained.

  The first binder resin preferably contains a component insoluble in tetrahydrofuran (THF) from the viewpoint of high temperature offset resistance. The THF-insoluble component content in the first binder resin added with wax is preferably 0.1 to 15% by weight, particularly 0.2 to 10% by weight, and more preferably 0.3 to 5% by weight.

(Coloring agent)
As the colorant used in the present invention, known pigments and dyes conventionally used as colorants for full-color toners can be used. For example, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, copper phthalocyanine, malachite green oxalate, lamp black, rose bengal, CI pigment red 48: 1 CI Pigment Red 122, CI Pigment Red 57: 1, CI Pigment Red 184, CI Pigment Yellow 97, CI Pigment Yellow 12, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Solvent Yellow 162 CI Pigment Yellow 180, CI Pigment Yellow 185, CI Pigment Blue 15: 1, CI Pigment Blue 15: 3, and the like. The content of the colorant in the toner particles is preferably in the range of 2 to 15 parts by weight with respect to 100 parts by weight of the total binder tree. It is preferable from the viewpoint of dispersibility that the colorant is used in the form of a masterbatch dispersed in a mixed binder resin of the first binder resin and the second binder resin used. The addition amount of the masterbatch may be an amount such that the amount of the colorant contained is within the above range. The colorant content in the masterbatch is preferably 20 to 40% by weight.

(Charge control agent)
In the toner of the present invention, a known charge control agent conventionally used in full color toners may be used.

  For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus Simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo And pigments and other high molecular compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used. The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(External additive)
In the present invention, in addition to the inorganic fine particles recited in the claims, other inorganic fine particles can be used as an external additive for assisting fluidity and developability.

  Specific examples of the inorganic fine particles include, for example, silicon oxide, zinc oxide, tin oxide, silica sand, titanium oxide, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, Examples thereof include zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

  The total amount of the external additive in the present invention is preferably 2.0 to 5.0 parts by mass with respect to the toner base. When the total amount of the external additive is larger than the above range, fogging, developability and fixing separation properties are deteriorated. When the total amount of external additives is less than the above range, fluidity, transferability, and heat-resistant storage properties are deteriorated.

(Manufacturing method)
The toner of the present invention is a toner having a desired particle size by mixing, kneading, pulverizing, and classifying the first binder resin, the second binder resin, and the colorant in which the hydrocarbon wax is internally added by a conventional method. Particles (colored resin particles) can be obtained and mixed with an external additive.

(Developer configuration)
As the developing roller, a roller coated with an elastic rubber layer is used, and a surface coat layer made of a material that is easily charged to a polarity opposite to that of the toner is provided on the surface. The elastic rubber layer is set to a hardness of 60 degrees or less according to JIS-A in order to prevent toner deterioration due to pressure concentration at the contact portion with the layer regulating member. The surface roughness Ra is set to 0.3 to 2.0 μm, and a necessary amount of toner is held on the surface. Since the developing roller is applied with a developing bias for forming an electric field between the developing roller and the photosensitive member, the elastic rubber layer is set to a resistance value of 10 ^{3 to} 10 ¹⁰ Ω. The developing roller rotates in the clockwise direction, and conveys the toner held on the surface to a position facing the layer regulating member and the photoconductor.

  The layer regulating member is provided at a position lower than the contact position between the supply roller and the developing roller. The layer regulating member is made of a metal leaf spring material such as SUS or phosphor bronze, and the free end is brought into contact with the surface of the developing roller with a pressing force of 10 to 40 N / m. The film is thinned and charged by frictional charging. Further, a regulation bias having a value offset in the same direction as the toner charging polarity with respect to the developing bias is applied to the layer regulating member in order to assist frictional charging.

  The rubber elastic body constituting the surface of the developing roller is not particularly limited. For example, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, urethane rubber, silicon rubber, A blend of two or more of these may be mentioned. Among these, a blend rubber of epichlorohydrin rubber and acrylonitrile-butadiene copolymer rubber is preferably used.

  The developing roller used in the present invention is manufactured, for example, by covering the outer periphery of a conductive shaft with a rubber elastic body. The conductive shaft is made of a metal such as stainless steel, for example.

  The configuration of the charging member of the electrostatic latent image holding member will be described.

The charging member of the present invention includes a metal core (3), a conductive layer (5) on the metal core (3), and a surface layer (6) covering the conductive layer, and is formed in a cylindrical shape as a whole. It is a thing. A voltage applied to the core metal (3) by the power source (7) is applied to the core metal (3) via the conductive layer (5) and the surface layer (6) to the latent image carrier (1). The surface of the latent image carrier (1) is charged. (See Figure 1)
The cored bar (3) of the charging member (2) is disposed along the longitudinal direction of the latent image carrier (1) (parallel to the axis of the latent image carrier (1)), and the charging member (2) The whole is pressed against the latent image carrier (1) with a predetermined pressing force. As a result, a part of the surface of the latent image carrier (1) and a part of the surface of the charging member (2) are brought into contact with each other along the longitudinal direction to form a contact nip having a predetermined width. The latent image carrier (1) is rotationally driven by a driving means (not shown), and the charging member (2) is configured to be driven and rotated accordingly.

  In FIG. 1, exposure means, development means, transfer means, and cleaning means are omitted.

  The latent image carrier (1) is charged by the power source (7) through the vicinity of the contact nip. Through the contact nip, the surface of the charging member (2) and the charged area (corresponding to the length of the charging member (2)) on the surface of the latent image carrier (1) are in contact with each other. The charged area on the surface of the carrier (1) is uniform.

  The conductive layer (5) of the charging member (2) is non-metallic, and a low hardness material can be preferably used in order to stabilize the contact state with the latent image carrier (1). For example, resins such as polyurethane, polyether, and polyvinyl alcohol, and rubbers such as hydrin, EPDM, and NBR are used. Examples of the conductive material include carbon black, graphite, titanium oxide, and zinc oxide.

The surface layer (6) is made of a material having a resistance value of medium resistance (10 ^{2 to} 10 ¹⁰ Ω).

  For example, nylon, polyamide, polyimide, polyurethane, polyester, silicon, Teflon (registered trademark), polyacetylene, polypyrrole, polytheophene, polycarbonate, polyvinyl, etc. can be used as the resin, in order to increase the contact angle with water. It is preferable to use a fluorine-based resin.

  Examples of the fluorine-based resin include polyvinylidene fluoride, polyvinyl fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, and vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer.

  Furthermore, for the purpose of adjusting to a medium resistance, a conductive material such as carbon black, graphite, titanium oxide, zinc oxide, tin oxide, or iron oxide may be added as appropriate.

  FIG. 2 shows an example of the image forming system of the present invention. In this image forming system, the photoconductor (11) rotates from the bottom to the top in the direction of the arrow. The developing roller (13) of the developing device (12) contacts the photoconductor (11) or holds a gap of about 0.1 to 0.3 and is driven as indicated by an arrow.

  The material of the developing roller (13) is composed of a metal conductor such as aluminum or stainless steel having a suitable surface roughness by sandblasting. A toner supply roller (14) is placed around the developing roller (13), a rubber plate (urethane rubber, silicon rubber, etc.) is attached to the leaf spring material, or a metal material regulating blade such as SUS (toner layer thickness regulating blade) (15) is arranged.

  In order to supply toner to the toner supply roller (14), a toner feed shaft (16) is rotatably disposed in a holding chamber (17) that holds toner.

  The present invention may also be configured as a process cartridge that can be attached to and detached from an image forming apparatus that uses the above-described image forming method.

  Hereinafter, the present invention will be specifically described by way of examples. In addition, this invention is not limited to the Example illustrated here.

(Creation of first binder resin)
As a vinyl monomer, 600 g of styrene, 110 g of butyl acrylate, 30 g of acrylic acid, and 30 g of dicumyl peroxide as a polymerization initiator were placed in a dropping funnel. Among polyester monomers, as polyols, 1230 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4 -Hydroxyphenyl) propane 290 g, isododecenyl succinic anhydride 250 g, terephthalic acid 310 g, 1,2,4-benzenetricarboxylic anhydride 180 g, dibutyltin oxide 7 g as esterification catalyst, wax as paraffin wax (melting point 73.3 ° C., differential 340 g (11.0 parts by weight with respect to 100 parts by weight of charged monomer) of 340 g of endothermic peak at the time of temperature rise measured by a scanning calorimeter at 4 ° C., thermometer, stainless steel stirrer, flow-down condenser, Place in a 5 liter four-necked flask equipped with a nitrogen inlet tube and a mantle heater In a nitrogen atmosphere, with stirring at a temperature of 160 ° C., it was added dropwise over one hour a mixture of the vinyl monomer resins and the polymerization initiator from the dropping funnel. The addition polymerization reaction was aged for 2 hours while maintaining the temperature at 160 ° C., and then the temperature was raised to 230 ° C. to perform the condensation polymerization reaction. The degree of polymerization was tracked by the softening point measured using a constant load extrusion capillary rheometer, and when the desired softening point was reached, the reaction was terminated to obtain Resin H1. The resin softening point was 130 ° C.

(Creation of second binder resin)
As polyol, 2210 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 850 g of terephthalic acid, 120 g of 1,2,4-benzenetricarboxylic anhydride and dibutyltin oxide 0 as esterification catalyst .5 g was put into a 5 liter four-necked flask equipped with a thermometer, a stainless steel stirrer, a falling condenser and a nitrogen inlet tube, and the temperature was raised to 230 ° C. in a mantle heater under a nitrogen atmosphere to conduct a condensation polymerization reaction. It was. The degree of polymerization was monitored by the softening point measured using a constant load extrusion capillary rheometer, and when the desired softening point was reached, the reaction was terminated to obtain Resin L1. The resin softening point was 115 ° C.

(Create toner particles)
After sufficiently mixing a master batch equivalent to containing 4 parts by mass of CIPigment Red 57-1 with 100 parts by mass of the binder resin composed of the first and second binder resins (including the weight of the internally added wax), using a Henschel mixer, Using a twin-screw extrusion kneader (PCM-30: manufactured by Ikekai Tekko Co., Ltd.), melt kneading, rolling the resulting kneaded material to a thickness of 2 mm with a cooling press roller, cooling with a cooling belt, and then using a feather mill Coarsely pulverized. After that, after pulverizing with a mechanical pulverizer (KTM: Kawasaki Heavy Industries, Ltd.) to an average particle size of 10-12 μm, and further pulverizing with a jet pulverizer (IDS: Nippon Pneumatic Co., Ltd.) while classifying coarse powder Then, fine powder classification was performed using a rotor type classifier (Teplex type classifier type: 100ATP: manufactured by Hosokawa Micron Corporation) to obtain colored resin particles 1. The particle diameter of the colored resin particles 1 was 7.5 μm.

  A desired amount (parts by mass) of inorganic fine particles was added to 1100 parts by mass of the colored resin particles and mixed with a Henschel mixer to obtain magenta toner particles.

  The magenta toners of Examples 1 to 4 were prepared under the conditions for the above toner particle preparation, and the magenta toners of Comparative Examples 1 to 8 were prepared. In Examples 1 to 4, the additives as inorganic fine particles were forsterite, alumina, cordierite, and aluminum nitride, respectively, and the formulations shown in Table 1 were used. In Comparative Example 1, no additive was added as a negative control. In Comparative Examples 2 to 4, the formulation shown in Table 1 was used with alumina as an additive. In Comparative Examples 5 to 8, the formulation shown in Table 1 was used with forsterite as an additive. All these additives were added in an amount of 1.5% with respect to 100 g of toner. In addition to the above additives, 2% of silica was added to 100 g of toner. Below, the manufacturing method of each additive is described.

(Method for producing forsterite)
The MgO-SiO2 oxide powder of the present invention is typically wet mixed and pulverized after Mg (OH) 2 powder or MgO powder and SiO2 powder having an average primary particle size of 10 [mu] m or less are dried and fired, and then wet pulverized again. And then dried and dry pulverized. The most important in this manufacturing process is twice wet pulverization. For example, if the wet pulverization after firing is omitted for simplification of the process, the MgO-SiO2 oxide powder cannot be finely divided and has a particle size of 1 μm or more. Therefore, it is not preferable.

  The Mg (OH) 2 powder and MgO powder are not particularly limited and may be general commercial products, but it is more preferable to use Mg (OH) 2 powder in terms of cost. preferable.

  The MgO powder or Mg (OH) 2 powder and SiO2 powder are slurried in water so that the molar ratio of MgO: SiO2 is 2: 1, and wet pulverized using a wet pulverizer such as a sand grinder mill. .

  The concentration of each raw material in the slurry is 50 to 200 g / L in terms of MgO and 30 to 150 g / L in terms of SiO2. The type of media may be any of alumina silica beads, zirconia beads, zircon beads, etc., the size of the media is 0.3 to 2.0 mmφ, the filling rate is 50 to 90%, and the number of passes of the slurry is 2 to 10 If this condition is not met, an MgO—SiO 2 oxide powder having a fine particle type and a uniform chemical composition cannot be obtained.

  The wet pulverization conditions are linked with the average primary particle diameter of the above-mentioned SiO2 powder in obtaining the fine particle type MgO-SiO2 oxide powder of the present invention, and therefore depending on the quality of the forsterite powder to be obtained. Can be made separately. For example, when manufacturing cost-reduced general-purpose products that allow about 1% of impurities due to media wear during wet grinding, inexpensive SiO2 powder with an average primary particle size of 1 to 10 μm is used. Strengthen grinding conditions to refine particles. In addition, when producing a high-purity fine particle type MgO-SiO2 oxide powder, use a fine particle SiO2 powder having an average primary particle diameter of 0.01 to 0.03 [mu] m and mixing impurities under moderate grinding conditions. Can be suppressed.

  The wet pulverized slurry is dried. The drying may be either spray drying or filtration drying of the slurry, but spray drying with a spray dryer that is advantageous in terms of cost and obtains a uniform particle size is preferable.

  Baking is performed in the air at 1000 to 1300 ° C. for 20 minutes to 2 hours in an electric furnace. Exceeding the temperature and time is not preferable because the MgO—SiO 2 oxide powder of the present invention cannot be obtained due to insufficient or excessive firing.

  The fired forsterite is wet pulverized using the wet pulverizer. This wet pulverization is as important as the wet pulverization at the time of raw material mixing, and it is preferable because the MgO-SiO2 oxide powder of the present invention cannot be obtained if this step is omitted or the wet pulverization conditions shown below are not satisfied. Absent.

(Codylite production method)
Rare earth element oxide powder having an average particle size of 10 μm or less is added to cordierite powder of 10 μm or less at a ratio of 1 to 20% by mass, preferably 5 to 15% by mass, more preferably 8 to 12% by mass. That is good. Densification is possible even with 100% by mass of cordierite without the addition of additives, but because the firing temperature is high and the calcinable temperature range is as narrow as ± 5 ° C, it is possible to stably produce a dense material. difficult. On the other hand, when the rare earth element is contained in an amount of 1% by weight or more, it reacts with the cordierite component during firing to produce a liquid layer, which has the effect of improving the sinterability and can be fired at a low temperature. At the same time, since the firing temperature range can be expanded to about ± 25 ° C., mass productivity can be improved. Examples of rare earth elements to be included in cordierite include Y, Yb, Lu, Er, Ce, Nd, and Sm. Among these, Y and Yb are preferable because they can be obtained at low cost.

  Although this rare earth element is present at the grain boundary of cordierite crystal, it is desirable that this rare earth element is present as a silicate compound crystal phase such as RE2O3.SiO2 or RE2O3.2SiO2. This is to reduce the thermal expansion coefficient of the substrate 1.

  A binder and a solvent were added, mixed for 24 hours, and dried to obtain a granulated powder. The firing temperature is 1375 ° C.

(Method for producing aluminum nitride)
Mixing of the aluminum nitride powder and the sintering aid powder can be performed by a known method. For example, a method of mixing by a dry method or a wet method using a mixer such as a ball mill can be suitably employed. In wet mixing, a dispersion medium such as alcohols and hydrocarbons is used, but alcohols and hydrocarbons are preferably used from the viewpoint of dispersibility.

  In this mixing, as described above, in order to prevent moisture adsorption or agglomeration of the sintering aid, the powder of the sintering aid that is stored in dry air and vacuum-dried if necessary is immediately used. It is better to mix with aluminum nitride powder.

  Examples of the organic binder include a butyral resin such as polyvinyl butyral, an acrylic resin such as polymethacrylbutyl, and such an organic binder is 0.1 to 30 parts by weight per 100 parts by weight of aluminum nitride powder. In particular, it can be used in an amount of 1 to 15 parts by weight. Examples of the dispersant include glycerin compounds, examples of the plasticizer include phthalate esters, and examples of the solvent include isopropyl alcohol and hydrocarbons. The mixed powder is mixed with an organic binder and, if necessary, a dispersant, a plasticizer, a solvent and the like to prepare a molding slurry or paste, and this molding slurry or paste is prepared.

  Degreasing can be performed by heating in any atmosphere such as air, nitrogen, hydrogen, etc. In particular, in the present invention, the residual carbon amount (content) after degreasing is specified as described later. Therefore, it is preferable to perform degreasing in nitrogen where the amount of residual carbon can be easily adjusted.

  The degreasing temperature varies depending on the type of organic binder, but generally 300 to 900 ° C, particularly 300 to 700 ° C is preferable. In addition, when it shape | molds without using an organic binder like the compression molding method, said degreasing process is unnecessary.

  In order to effectively remove the sintering aid and reduce the metal impurity concentration and oxygen concentration in the sintered body, firing is performed in a reducing atmosphere.

  Examples of the method for realizing the reducing atmosphere include a method in which a carbon generation source coexists with a molded body in a firing container, a method using a carbon product as a firing container, and the like. Considering the thermal conductivity and color unevenness of the obtained sintered body, a method in which the molded body and the carbon generation source coexist in the firing container is suitable, and in particular, in order to obtain a high thermal conductivity. The most preferable method is to use a container for firing as a sealed container, and to accommodate the compact and the carbon generation source in the sealed container.

(Alumina production method)
The alumina sintered body comprises 70 to 100% by weight of alumina fine powder having an average particle size of 5 to 50 nm, 0 to 20% by weight of alumina powder having an average particle size of 0.5 to 3.0 μm, and an additive for an alkaline earth metal compound It is obtained by producing a molded body of 0 to 10% by weight and calcining it in a temperature range of 900 to 1200 ° C. in an atmosphere containing water vapor of 0.005 atm or more and 0.85 atm or less with a partial pressure. .

  Here, it is difficult to obtain an alumina powder having an average particle size of less than 5 nm. Further, when the average particle size is 50 nm or more, the sinterability at 1200 ° C. or less is remarkably lowered. For this reason, the particle diameter of the alumina fine powder of the raw material powder needs to be in the range of 5 to 50 nm. The range of 5 to 20 nm is more preferable.

  The addition of the alkaline earth metal compound has an effect of promoting the progress of sintering. Compared with the case where no additive is added, the firing time until the equivalent density is reached is shortened. Here, it is not desirable that the addition amount be 10% by weight or more. This is because the dielectric loss factor of the sintered body is increased by increasing the amount of subcomponents, and the characteristics comparable to those of conventional alumina can be achieved when the addition amount is 10% by weight or less.

  Sinterability improves as the water vapor content in the firing atmosphere increases. The effect is not recognized at all when the partial pressure is 0.005 atm or less. On the other hand, it is difficult to obtain an atmosphere containing 0.85 atm or more. Therefore, the amount of water vapor is preferably 0.005 atm or more and 0.85 atm or less in partial pressure. More preferably, the range of 0.3 to 0.7 atm is easily obtained, and the effect is sufficiently confirmed. By firing under the above conditions, an alumina sintered body can be obtained at a firing temperature of 900 to 1200 ° C. Further, 0 to 20% by weight of alumina powder having a particle size of 0.5 to 3.0 μm can be added as an alumina component. This addition is effective for controlling the amount of shrinkage caused by firing. However, the addition of alumina powder having a particle size of 0.5 μm or less has no effect on shrinkage control. Adding alumina powder having a particle size of 0.5 μm or more to the raw material powder results in a decrease in sinterability, but if the addition amount is up to 20% by weight or less of alumina powder having a particle size of 3.0 μm or less, the sinterability is remarkably increased. There is no reduction.

(Adjustment method of relative permittivity and dielectric loss tangent)
In general, the electrical characteristics vary depending on the firing conditions. When the firing temperature is high, densification of the ceramic progresses and high dielectric constant and low dielectric loss tangent are promoted. Below, the baking conditions of each Example and a comparative example are shown.

Example 1: Forsterite additive 1100 ° C./2 hr
Example 2: Alumina additive 1100 ° C / 3hr
Example 3: Cordierite additive 1375 ° C / 2hr
Example 4: Aluminum nitride additive 1780 ° C / 50hr
Comparative Example 1: Negative control (no additive)
Comparative Example 2: Alumina additive 1300 ° C / 3hr
Comparative Example 3: Alumina additive 1200 ° C / 3hr
Comparative Example 4: Alumina additive 1550 ° C / 3hr
Comparative Example 5: Forsterite additive 1100 ° C./2 hr
Comparative Example 6: Forsterite additive 1200 ° C / 2hr
Comparative Example 7: Forsterite additive 1300 ° C / 2hr
Comparative Example 7: Forsterite additive 1300 ° C / 2hr
(Evaluation)
(Toner particle size (Coulter))
A method for measuring the particle size distribution of the toner particles will be described. Examples of the measuring device for the particle size distribution of toner particles by the Coulter counter method include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below. First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added as a solid content. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the volume and number of toner particles or toner using a 100 μm aperture as an aperture. Volume distribution and number distribution are calculated. From the obtained distribution, the weight average particle diameter (Dv) and the number average particle diameter (Dp) of the toner can be obtained. The channels include: 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; .35 to less than 8.00 μm; 8.00 to less than 10.08 μm; 10.08 to less than 12.70 μm; 12.70 to less than 16.00 μm; 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

(X-ray fluorescence analysis)
The tube voltage was 5 KV, the tube current was 30 mA, the measurement time was 40 seconds, the measurement angles were Mg—KA 38.370 °, and the AL-KA 144.372 ° calibration curve method.

(Electrical characteristics evaluation)
It measured according to the measuring method of JIS C2141.

(Adhesion strength)
A surfactant and toner were put in water, energy was applied at 40 W for 1 minute with an ultrasonic homogenizer, the toner was separated and dried, and the ratio of the amount of adhesion before and after treatment was calculated using a fluorescent X-ray analyzer. . For the fluorescent X-ray analysis conditions, see the above (fluorescent X-ray analysis).

(Dispersion diameter)
An SEM photograph of the externally added toner was taken and the average particle size was calculated using Luzex AP manufactured by Nireco.

  Table 1 shows the relative dielectric constant, dielectric loss tangent, adhesion strength, and average particle diameter in each of the examples and comparative examples.

（画像評価）
リコー社製カラーレーザープリンターIPSIO CX2500を用いて画像評価を行った。評価項目と評価基準を以下に示す。
・地汚れ：黒ベタ画像を採取後、白べた画像の白さ度合いを目視評価
・画像濃度：黒べた現像時の感光体上トナー付着量で代用
・黒ベタ追従性：黒ベタ画像の連続印刷における黒さの追従性を感光体上トナー付着量で代用
・トナー消費量：耐久中の単位枚数あたりのトナーホッパ重量減量
それぞれ目標品質上問題ないレベルを○、問題レベルを×、目標品質レベルに及ばないものの重大な問題ではないレベルを△とした。

(Image evaluation)
Image evaluation was performed using a Ricoh color laser printer IPSIO CX2500. Evaluation items and evaluation criteria are shown below.
-Ground stain: After collecting a black solid image, visually evaluate the degree of whiteness of the solid white image.-Image density: Substitute with the toner adhesion amount on the photoconductor during black solid development.-Solid black follow-up: Continuous printing of solid black image. Substituting the amount of toner on the photoconductor for the follow-up of blackness in toner. Toner consumption: Weight reduction of the toner hopper per unit sheet during durability. A level that was not a serious problem but was not marked as △.

  Table 2 shows the results.

表２の結果から分かるように、トナー粒子の添加剤の比誘電率が１乃至９、誘電正接が５Ｅ−５乃至１Ｅ−３、付着強度が５０乃至８０％及び平均粒子径が１００乃至５００ｎｍである実施例１乃至４が、良好な画像結果を得た。

As can be seen from the results in Table 2, the relative dielectric constant of the toner particle additive is 1 to 9, the dielectric loss tangent is 5E-5 to 1E-3, the adhesion strength is 50 to 80%, and the average particle size is 100 to 500 nm. Examples 1 to 4 gave good image results.

  Therefore, according to the present invention described above, according to the present invention, a ground stain due to charging failure does not occur, and an electrophotographic image with excellent image quality can be obtained with a sufficient image density.

  The toner particles for developing an electrostatic latent image of the present invention are such that the inorganic fine particles contained in the toner have a relative dielectric constant and a dielectric loss tangent of 1 to 9, 5E-5 to 1E-3 at a frequency of 1 MHz, respectively, and A toner for developing an electrostatic latent image, wherein the adhesion strength of the inorganic fine particles is 50 to 80%, and the dispersion diameter distribution of the inorganic fine particles on the toner surface is 100 to 500 nm. If the relative dielectric constant is less than 1, the charge level is low, and therefore background contamination due to poor charging tends to occur. On the other hand, if the relative dielectric constant is higher than 9, the charge level becomes high, so that developability is lowered and sufficient image density cannot be obtained.

  There is no problem if the dielectric loss tangent is smaller than 5E-5, but it is not substantially smaller than this value. Further, if the dielectric loss tangent is larger than 1E-3, the charge rising property is deteriorated, so that the background contamination due to poor charging is likely to occur.

  If the adhesion strength of the inorganic fine particles is less than 50%, the amount of the third component present is large, so that it moves like a charged toner, resulting in image noise. There is no problem even if it is larger than 80%, but it is not substantially larger than this value.

  The dispersion diameter is fixed to the toner and needs a certain size in order to satisfy the function as a charge aid. If it is 500 nm or more, it is difficult to be immobilized on the toner base, and if it is 100 nm or less, it cannot function sufficiently as a charge aid.

  If the addition amount of the inorganic fine particles is 0.1% or less, the effect of promoting the charge of the inorganic fine particles is reduced, and if it is 2.5% or more, it is difficult to fix the toner base material efficiently.

  When the volume average particle diameter of the toner particles is larger than 10 μm, the specific surface area of the toner becomes small, so that sufficient adhesion cannot be obtained, and when it is smaller than 5 μm, the electrophotographic process cannot be used well. In particular, the toner particles for developing an electrostatic latent image of the present invention are suitable for a developing method using a one-component developer.

  Therefore, the optimum relative dielectric constant, dielectric loss tangent, adhesion strength, and dispersion diameter as a charging aid for raising the charge to a desired charge level for development within a moment passing through the regulating means and maintaining the charge. Exists.

  Although the embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and these embodiments of the present invention depart from the spirit and scope of the present invention. And can be changed or modified.

It is a figure which shows an example of the charging member of this invention. It is a figure which shows an example of the image formation system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Latent image carrier 2 Charging member 3 Core metal 5 Conductive layer 6 Surface layer 7 Power source 11 Photoconductor 12 Developing device 13 Developing roller 14 Toner supply roller 15 Toner layer thickness regulating blade 16 Toner feed shaft 17 Holding chamber

Claims (14)

In a toner in which inorganic fine particles are externally added to a toner base composed of at least a binder resin and a colorant,
The inorganic fine particles have a relative dielectric constant and dielectric loss tangent at a frequency of 1 MHz of 1 to 9, 5E-5 to 1E-3, respectively, and the adhesion strength of the inorganic fine particles to the toner base is 50 to 80%. A toner for developing an electrostatic latent image, wherein a dispersion diameter distribution of the inorganic fine particles is 100 to 500 nm. The electrostatic latent image developing toner according to claim 1, wherein the inorganic fine particles are a complex oxide represented by the following general formula.
[M1] aSibOc
(In the formula, M1 represents a metal element selected from Sr, Mg, Zn, Co, Mn and Ce, a and b represent an integer of 1 to 9, and c represents an integer of 3 to 9)   3. The electrostatic latent image developing toner according to claim 1, wherein the inorganic fine particles are magnesium silicate in which M1 in the general formula is Mg.   The electrostatic latent image developing toner according to claim 1, wherein the inorganic fine particles are forsterite.   5. The content determined by magnesium element when using a wavelength dispersive X-ray fluorescence analyzer is 0.1 to 2.5% based on the toner weight. The toner for developing an electrostatic latent image according to one item.   2. The electrostatic latent image developing toner according to claim 1, wherein the inorganic fine particles are alumina or aluminum nitride.   7. The electrostatic charge latent image developing device according to claim 6, wherein the content determined by the aluminum element by the wavelength dispersive X-ray fluorescence analyzer is 0.1 to 2.5% based on the toner weight. toner.   2. The electrostatic latent image developing toner according to claim 1, wherein the inorganic fine particles are cordierite.   The electrostatic charge latent image developing toner according to claim 1, wherein the toner has a volume average diameter of 5 to 10 μm.   10. The electrostatic latent image developing toner according to claim 1, wherein the electrostatic latent image developing toner is a non-magnetic one-component developing toner.   A developer using the toner for developing an electrostatic latent image according to claim 1. At least a rotatable image carrier;
A contact charging member disposed in contact with the image carrier and charging the image carrier to a predetermined potential;
11. An image forming method using a rotating toner conveying member and a developing device having a toner supply member that supplies toner to the conveying member, wherein the toner is a static device according to any one of claims 1 to 10. An image forming method comprising a toner for developing a latent charge image.   13. An image forming apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transfer unit, a cleaning unit, and a photoconductor, wherein the image forming method according to claim 12 is used. apparatus. At least a rotatable image carrier;
A contact charging member disposed in contact with the image carrier and charging the image carrier to a predetermined potential;
11. A process cartridge provided with a developing device having a rotating toner conveying member and a toner supply member for supplying toner to the conveying member, wherein the toner is a detachable process cartridge, wherein the toner is any one of claims 1 to 10. A process cartridge comprising the electrostatic latent image developing toner according to claim 1.

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