JP4640230B2 - Toner for electrostatic image development - Google Patents

Description

  The present invention relates to an electrostatic charge image developing toner used in electrophotography, electrostatic photography, and the like. More specifically, a specific external additive adheres to the surface of toner base particles having a specific configuration. The present invention relates to an electrostatic charge image developing toner.

  In the electrophotographic printing method based on the full-color development system that enables multi-color development, the development of non-magnetic one-component toners that are mainly made from pulverized toners using polyester resins has led to the downsizing of printing machines and accompanying this. There has been achieved a technique that satisfies the demand for miniaturization of the cartridge, achieves both the image reproducibility of color reproducibility, glossiness, transparency, and the like required for color images, and solves the problem of toner thermal welding.

  On the other hand, due to further market demands, higher resolution of images is required, toner is required to have a smaller particle size, and in order to increase the printing speed, more fixability and release There is also a demand for development of toner with improved properties. In order to achieve such a demand, development of so-called polymerized toners, which are smaller-sized toners, can freely control the circularity, and can increase the wax content, has been actively promoted. Polymerized toners having such advantages require the possibility of applying styrene / acrylic resins to non-magnetic one-component full color toners instead of conventional polyester resins.

  That is, the styrene / acrylic resin suitable for the production with the polymerized toner has the disadvantage that the mechanical strength is inferior to that of the polyester resin, and therefore the resistance to friction by the charging blade at the time of frictional charging in the contact development method is low. . In order to improve this point, a technique for adding a shell agent having excellent mechanical strength to toner base particles made of styrene / acrylic resin is also provided.

  On the other hand, even with polymerized toners, as with pulverized toners, the problems of fluidity in the developer tank, charging characteristics, fogging based on this, prevention of image quality stains, and filming must be solved. Are the same. However, no technology that can comprehensively solve the above problems has been provided for the external addition formulation of silica fine particles for imparting such fluidity in the polymerized toner. That is, for the external additive formulation of silica itself, in order to improve fluidity on the one hand and prevent deterioration of fluidity due to long run on the one hand from the era of pulverized toner, a relatively small particle size is used for the former purpose. It is well known that a formulation in which silica is added and a relatively large particle size silica is added for the latter purpose is beneficial.

  However, the large particle size silica prevents the embedding of the small particle size silica, which ensures fluidity, into the toner base particles during a long run, and in turn helps to ensure long-term stability of the fluidity. As a characteristic of the large particle size silica, there is a problem of separation from the toner base particles. The large particle size silica separated from the toner base particles tends to remain on the photosensitive drum more than the toner base particles, and the photosensitive drum is damaged when it passes through the cleaning blade. In addition to causing the problem of the mixing, it is attracted to and adhered to the waiting photosensitive member charging roller (hereinafter referred to as “PCR contamination”), and the surface potential of the photosensitive member is lowered. As a result, in the case of the reversal development method often used in full-color printers, the development is caused at the image position that should originally be a white background, thereby causing problems such as image smearing.

  In this regard, if there is a problem of filming and a problem of deterioration of the charging characteristics of the photosensitive member charging roller due to PCR contamination, it can be avoided by a design change such as appropriately reducing the particle size of the large particle size silica. In Patent Document 1, etc., silica with a reduced particle size is added. However, if the particle size of silica is reduced with the same toner base particles as in the past, the expected effect of preventing embedding during a long run can be sufficiently obtained. Absent. In addition, prescriptions such as using titania, which is an external additive with low resistance, can be considered. However, titania does not have a sufficiently negative charge sequence, and the toner has sufficient negative charge necessary for reversal development. In general, it is difficult to use. This is the same even when alumina having a strong charging tendency and a positive charging tendency is used.

As described above, the problem of PCR contamination is not simply a problem that can be controlled by the particle size of the silica fine particles, and even if an external additive other than the silica fine particles is examined, adverse effects on the chargeability and the like. There is no known effective means for sufficiently Therefore, when trying to use silica fine particles, a drastic improvement study has been required.
JP 2004-163807 A

  The present invention has been made in view of the above-described background art, and the problem is that the fluidity of the toner in the developing tank is stabilized for a long period of time, and no filming occurs due to the desorption of silica fine particles as a flow improver. An object of the present invention is to provide a toner for developing an electrostatic charge that has little contamination (PCR contamination) to a cartridge member such as a body charging roller, maintains a chargeability imparting function, and can suppress an increase in fog during running use. .

  As a result of intensive studies to solve the above-mentioned problems, the present inventor stabilizes the fluidity of the toner for a long time by attaching specific silica fine particles to toner base particles having a specific configuration. On the other hand, the inventors have found that filming and PCR contamination can be reduced, the function of imparting charging property can be maintained, and the increase in fog can be suppressed, and the present invention has been completed.

That is, according to the present invention, the BET value obtained by surface treatment with hexamethyldisilazane is 50 to 100 parts by weight of toner base particles having a structure in which resin fine particles are coated on the surface of core particles obtained by a wet method. 0.05 to 3 parts by weight of silica fine particles of 100 m ² / g and 0.05 to 2 parts by weight of silica fine particles having a BET value greater than 100 m ² / g surface-treated with hexamethyldisilazane are attached. The present invention provides a toner characterized by the above.

  According to the present invention, the initial fluidity is good, the fluidity is not deteriorated even when used for a long time, filming and PCR contamination can be reduced, and the charge amount is stabilized by maintaining the function of imparting chargeability for a long time. Therefore, it is possible to provide a toner for developing an electrostatic charge that can suppress an increase in fog.

  Hereinafter, although this invention is demonstrated, this invention is not limited to the following specific aspects, As long as the summary is not exceeded, it can deform | transform and implement arbitrarily.

  In the toner used in the present invention, the surface of core particles obtained by a wet method is coated with resin fine particles, and specific silica fine particles are further adhered thereto.

  The core particle contains at least a binder resin and a colorant. As the binder resin for the core particles of the toner of the present invention, various known resins can be used as the toner resin. However, in the present invention, core particles are obtained by a wet method. It is done.

  The raw material polymerizable monomer used in the styrenic resin is not particularly limited. Specifically, for example, styrenes such as styrene, p-methylstyrene, α-methylstyrene, chlorostyrene, dichlorostyrene; vinyl acetate, Maleic anhydride, acrylic acid ester, methacrylic acid ester, acrylic acid, methacrylic acid, (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, vinyl chloride, propylene, butadiene, etc. Is preferred. Among these, (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate, (meth) Preference is given to octyl acrylate, phenyl (meth) acrylate, hydroxyethyl (meth) acrylate and the like. These polymerizable monomers may be used alone or in combination.

  As the styrene-based resin, a (co) polymer of the above polymerizable monomer is preferable, but a styrene- (meth) acrylic acid ester copolymer, a styrene- (meth) acrylic acid ester- (meth) acrylic acid copolymer, etc. Are particularly preferable, and those having an acid group such as a styrene- (meth) acrylic acid ester- (meth) acrylic acid copolymer are excellent in terms of fixing properties and durability of the toner, and charge stability of the toner. (Especially negative chargeability) is improved, which is more preferable.

  Furthermore, a polyfunctional monomer can also be used as the polymerizable monomer. Examples of the polyfunctional monomer include divinylbenzene, hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diallyl phthalate, and the like. It is also possible to use a polymerizable monomer having a reactive group in a pendant, such as glycidyl (meth) acrylate, methylol (meth) acrylamide, acrolein or the like. Among these, radical polymerizable bifunctional monomers are preferable, and divinylbenzene, hexanediol di (meth) acrylate, and the like are particularly preferable. These polyfunctional monomers may be used alone or in combination.

  The number average molecular weight of the binder resin of the core particles of the toner of the present invention measured by gel permeation chromatography (hereinafter abbreviated as “GPC”) is not particularly limited, but is preferably 2000 or more, more preferably It is 2500 or more, more preferably 3000 or more, and the upper limit is preferably 50,000 or less, more preferably 40,000 or less, and still more preferably 35,000 or less. Further, the weight average molecular weight determined by GPC is preferably 10,000 or more, more preferably 30,000 or more, still more preferably 50,000 or more, and the upper limit is preferably 200,000 or less, more preferably 120,000 or less, and further Preferably it is 80,000 or less. It is preferable that the number average molecular weight and the weight average molecular weight of the styrene resin are in the above ranges because the durability, storage stability, fixability and the like of the toner are improved.

  The glass transition point (hereinafter abbreviated as “Tg”) of the binder resin of the core particles is not particularly limited, but is preferably 30 ° C. or higher, and particularly preferably 40 ° C. or higher. The upper limit is preferably 80 ° C. or less, and particularly preferably 70 ° C. or less. If the Tg is too low, the storage stability of the toner may be impaired. On the other hand, if the Tg is too high, the toner fixability may be remarkably deteriorated.

  “Tg” in the present invention is a DSC 220 manufactured by Seiko Instruments Inc. The first time the temperature is raised from 30 ° C. to 210 ° C. at 10 ° C./min, then the temperature is lowered to 30 ° C. at 20 ° C./min, and further to 110 ° C. A tangent is drawn to the transition (inflection) start portion of the DSC endothermic curve when the temperature is raised in minutes, and this is defined as the temperature at the intersection of the two tangents.

  The softening point (hereinafter abbreviated as “Sp”) of the binder resin of the core particles is not particularly limited, but is preferably 80 ° C. or higher, and particularly preferably 90 ° C. or higher. Moreover, it is preferable that an upper limit is 160 degrees C or less, and 150 degrees C or less is especially preferable. If Sp is too low, the toner may be fused to a heat roller or the like in the fixing process, and a so-called offset problem may occur. On the other hand, if Sp is too high, the toner fixability may be remarkably deteriorated.

  “Sp” in the present invention is a flow tester (CFT-500 manufactured by Shimadzu Corporation), a sample of 1.0 g, a nozzle 1 mm × 10 mm, a load 30 kg, a preheating time 50 ° C. for 5 minutes, and a temperature rising rate 3 ° C./min. It is defined as the temperature at the midpoint of the strand from the start to the end of the flow when the measurement is performed under conditions.

  The core particles can contain a colorant. There are no particular limitations on the colorant contained in the core particles, and various known materials suitable for toners can be used. For example, carbon blacks such as furnace black and lamp black; benzidine yellow, benzidine orange, quinoline yellow, Acid green, alkali blue, rhodamine, magenta, macalite green, hydroxyanthraquinone, phthalocyanine dye, pigment, quinacridone dye, dioxane dye, aniline black, azo dye, naphthoquinone dye, indigo dye, nigrosine And synthetic dyes such as di- and triarylmethane dyes and the like, and two or more of these may be used in combination.

  When the toner of the present invention is used as a full-color toner, an azo pigment (insoluble monoazo, insoluble disazo, condensed azo, etc.) or polycyclic pigment (isoindoline, isoindolinone, selenium) is used for yellow. , Quinophthalone, etc.) and mazota pigments such as azo pigments (azo lake, insoluble monoazo, insoluble disazo, condensed azo, etc.), polycyclic pigments (quinacridone pigment, perylene pigment, etc.), etc. Examples of cyan pigments include phthalocyanine pigments and selenium pigments. The combination of the colorants may be appropriately selected in consideration of the hue and the like. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. At least one selected from CI Pigment Yellow 155 is C.I. I. Pigment red 238, C.I. I. Pigment red 269, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 48: 2, C.I. I. At least one selected from CI Pigment Red 122 is C.I. I. Pigment blue 15, C.I. I. At least one selected from CI Pigment Blue 15: 3 is preferable as furnace black carbon as the black colorant. It is preferable to use a colorant that contains as little volatile impurities as possible.

  It is also preferable that the core particles contain a wax. The wax is not particularly limited as long as it is usually used in toner applications, and specifically, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and copolymerized polyethylene; paraffin wax; silicon wax having an alkyl group A higher fatty acid such as stearic acid; a long-chain aliphatic alcohol such as eicosanol; an ester wax having a long-chain aliphatic group such as behenyl behenate, a montanic acid ester, and stearyl stearate; a long-chain alkyl group such as distearyl ketone; Ketones having hydrogen peroxide; plant waxes such as hydrogenated castor oil and carnauba wax; esters or partial esters obtained from polyhydric alcohols such as glycerin and pentaerythritol and long chain fatty acids; higher grades such as oleic acid amide and stearic acid amide Fatty acid amide; low Molecular weight polyester, and the like are preferable. As the wax particularly suitable for the present invention, it can be suitably used by selecting from olefin waxes such as ester wax, paraffin wax, low molecular weight polypropylene and copolymer polyethylene, and silicone wax having an alkyl group. The wax preferably has at least one endothermic peak due to DSC at 50 to 100 ° C. from the viewpoint of fixability.

  Further, a charge control agent may be contained for imparting charge amount and charge stability. As the charge control agent, conventionally known compounds are used. For example, as the positive charge control agent, nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, polyamine resins, etc. As the negatively chargeable charge control agent, azo complex compound dyes, alkyl salicylic acid complex compounds, calixarene compounds and the like containing atoms such as Cr, Co, Al, Fe and B are preferable. For full-color toners, the color tone of the charge control agent must be colorless or light in order to avoid a color tone failure as a toner. The agent is preferably a quaternary ammonium salt or an imidazole compound, and the negative charge control agent is an alkyl salicylic acid complex compound or calixarene compound containing atoms such as Cr, Co, Al, Fe, B, etc. Is preferred. Moreover, these mixtures may be sufficient. The addition amount of the charge control agent is preferably in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

  Further, various known internal additives such as silicon oil and silicon varnish can be contained for modifying the adhesiveness, cohesiveness, fluidity, chargeability, surface resistance and the like of the toner.

  The core particle of the toner of the present invention is obtained by a wet method, but if it is a wet method, a method for producing the core particle is not particularly limited, and a polymerization method such as an emulsion polymerization aggregation method or a suspension polymerization method, Any of the resin dissolution suspension methods and the like can be suitably used. Among these, from the viewpoint of easy control of the particle size distribution and circularity of the obtained toner, and further from the viewpoint of ease of subsequent coating of resin fine particles, it is preferable to produce by a polymerization method. It is particularly preferable to produce by an emulsion polymerization aggregation method.

  A conventionally known method can be used as the emulsion polymerization aggregation method. That is, the polymerizable monomer constituting the polymer primary particles is emulsified in an aqueous medium containing a polymerization initiator and an emulsifier, and the polymerizable monomer is polymerized with stirring to produce an emulsion of the polymer primary particles first. Next, a colorant and, if necessary, a charge control agent are added to the obtained polymer primary particle emulsion to agglomerate the polymer primary particles to form an aggregate, and then a fusion step is performed if necessary. After that, core particles are obtained.

  Here, wax is added as a seed during emulsion polymerization to be contained in the polymer primary particles, or when the polymer primary particles are aggregated, the wax fine particles are mixed and co-aggregated, or a combination thereof is added. Is also preferable. Among these, it is particularly preferable to add substantially all of the wax as a seed during emulsion polymerization. Specifically, a method is preferred in which wax is first dispersed in an aqueous medium as a seed serving as a polymerization nucleus, and then a polymerizable monomer is introduced dropwise to produce polymer primary particles of a binder resin. In this method, it is possible to encapsulate wax in each particle unit before agglomeration, so that leakage from the toner surface after subsequent aggregation and fusing steps, resulting in binding and fusing of toner resins with each other. It is possible to prevent wearing and the like, which is preferable. Further, by adding as a seed during wax emulsion polymerization, the wax is finely and uniformly dispersed in the toner, so that deterioration of the charging property and heat resistance of the toner can be suppressed.

  When the core particles of the toner of the present invention are produced by suspension polymerization, they can be produced according to a conventionally known method. That is, usually, each component such as a polymerizable monomer, a polymerization initiator, a colorant, and a wax, a charge control agent, and an internal additive constituting a binder resin described later in an aqueous medium, a disperser, etc. It can be obtained by suspending and dispersing to an appropriate particle size using a disperser, and then polymerizing the polymerizable monomer. Moreover, also when manufacturing with a resin solution suspension method, it can manufacture in accordance with a conventionally well-known method.

  The toner base particles in the toner of the present invention have a structure in which resin fine particles are coated on the surface of the core particles obtained by the wet method. In the present invention, among the toner base particles, core particles are produced, and further, leakage prevention from the core particles to the surface of the wax, etc., compensation for insufficient mechanical strength of the core particles, improvement of storage stability, etc. Therefore, a resin particle that forms a shell having a higher strength or a high glass transition point is attached to the surface of the core particle, and then fused to form a shell, whereby a toner having a two-layer or three-layer structure is obtained. is necessary. Therefore, the “configuration coated with resin fine particles” means a configuration with a history of coating resin fine particles, and the surface of the toner base particles in the present invention may maintain the shape of the resin fine particles, The shape of the resin fine particles may not be maintained by fusing. Moreover, the intermediate stage may be sufficient.

  There are no particular limitations on the raw material and manufacturing method of the resin fine particles that form the shell, but it is preferably manufactured using the same raw material and manufacturing method as the above-described polymer primary particles for core particles. That is, an emulsion of resin fine particles is produced by emulsifying the polymerizable monomer constituting the resin fine particles in an aqueous medium containing a polymerization initiator and an emulsifier, and polymerizing the polymerizable monomer under stirring. Is preferred.

  The method for coating the resin particles with the core particles is not particularly limited. In the state where the core particles obtained by the polymerization method are dispersed in water, the resin particle emulsion for constituting the shell is mixed with the core particles. The surface of the core particles is preferably coated with resin fine particles, and further heated to produce toner base particles having a structure in which the core particles are covered with a shell.

  Further, the method of coating the resin particles with the core particles obtained by the resin dissolution suspension method is not particularly limited. For example, for the aqueous dispersion of the core particles obtained by distilling off the organic solvent, the same method as the above coating method is used. Can be used.

  As the polymerizable monomer used as the raw material for the resin fine particles, those used as the raw material for the binder resin for the core particles described above are similarly suitably used. Further, as the binder resin for the resin fine particles, those preferable as the binder resin for the core particles can be preferably used as well.

  The number average molecular weight obtained by GPC of the shell binder resin (of the resin fine particle binder resin) in the toner of the present invention is not particularly limited, but is preferably 2000 or more, more preferably 2500 or more, and still more preferably 3000 or more. Preferably, it is 50,000 or less, more preferably 40,000 or less, and still more preferably 35,000 or less. The weight average molecular weight determined by GPC is preferably 10,000 or more, more preferably 30,000 or more, still more preferably 50,000 or more, preferably 200,000 or less, more preferably 120,000 or less, and still more preferably 8 It is desirable to be 10,000 or less. When the number average molecular weight and the weight average molecular weight are in the above ranges, the durability, storage stability, fixing property and the like of the toner are improved, which is preferable.

  Furthermore, at least one of the peak molecular weights in GPC of the resin fine particles in the present invention is preferably 3000 or more, more preferably 10,000 or more, still more preferably 30,000 or more, preferably 100,000 or less, more preferably 70,000. Hereinafter, it is more preferable that it exists in 60,000 or less. When the peak molecular weight is in the above range, the durability, storage stability, and fixability of the toner are good. Here, as the peak molecular weight, a value converted to polystyrene is used, and components insoluble in a solvent are excluded in measurement.

  The Tg of the binder resin of the resin fine particles is preferably 65 ° C. or higher. Especially preferably, it is 70 degreeC or more, More preferably, it is 75 degreeC or more. The upper limit is preferably 100 ° C. or lower, particularly preferably 90 ° C. or lower, and further preferably 85 ° C. or lower. When the Tg is less than 65 ° C., the external additive is excessively embedded in the surface of the toner base particles, which may lead to a decrease in storage stability due to fluidity deterioration, generation of fog due to a decrease in charge amount, image contamination, and the like. . On the other hand, if Tg is too high, the adhesion strength of the external additive to the toner base particles becomes weak, and as a result, the external additive may be released from the surface of the toner base particles. In some cases, the charging roller portion is contaminated and image contamination occurs. Further, since the fixing temperature range on the low temperature side is narrowed, fixing failure may occur particularly when printing is performed at high speed.

  The Tg of the resin resin binder resin is 5 ° C. or more, preferably 10 ° C. or more, more preferably 15 ° C. or more higher than that of the core particle binder resin, such as blocking resistance, storage stability, durability, etc. This is preferable.

  The softening point of the binder resin of the resin fine particles (hereinafter abbreviated as “Sp”) is not particularly limited, but is preferably 80 ° C. or higher, particularly 90 ° C. or higher, as in the case of the core particles. preferable. Moreover, it is preferable that an upper limit is 160 degrees C or less, and 150 degrees C or less is especially preferable. If Sp is too low, the toner may be fused to a heat roller or the like in the fixing process, and a so-called offset problem may occur. On the other hand, if Sp is too high, the toner fixability may be remarkably deteriorated.

  In addition, by providing a resin fine particle with a wax, a toner that does not deteriorate the high temperature offset resistance, blocking resistance, etc. even if the low temperature fixability is improved by adjusting the composition, composition, etc. of the core particles is provided. Is preferable. The same method as described in the production of the polymer primary particles for producing the core particles in the emulsion polymerization aggregation method is preferable for the same reason. Even when the resin fine particles contain a wax, the above Tg means the Tg of only the binder resin portion of the resin fine particles.

  When the resin fine particles contain a wax, the same wax as the wax contained in the core particle is preferably used. It is also preferable to add a charge control agent to the resin fine particles. Further, various known internal additives can be incorporated for the purpose of modifying the adhesiveness, cohesiveness, fluidity, charging property, surface resistance, etc. of the toner.

  The volume average diameter (Mv) of the resin fine particles is not particularly limited, but is preferably 20 nm or more, particularly preferably 50 nm or more, more preferably 100 nm or more, and the upper limit is preferably 400 nm or less, particularly preferably 300 nm or less, More preferably, the thickness is 250 nm or less. If the particle size is less than the above range, in the resin fine particle adhesion step to the toner, since only the resin fine particles are likely to aggregate, it may be difficult to uniformly adhere the resin to the toner surface. Since the Tg of the resin fine particles is high, the fixability may be adversely affected.

Volume average diameter (Mv) is manufactured by Nikkiso Co., Ltd. Model: Microtrac Nanotrac 150 (hereinafter abbreviated as “Nanotrack”), according to the nanotrack instruction manual, Microtrac Particle Analyzer Ver10.1.2 Using .-019EE, using ion-exchanged water with an electric conductivity of 0.5 μS / cm as the dispersion medium, measuring under the following conditions or entering the following conditions, and measuring according to the method described in the instruction manual, Is defined as the measured value.
Solvent refractive index: 1.333
-Measurement time: 100 seconds-Number of measurements: 1 time-Particle refractive index: 1.59
-Permeability: Transmission-Shape: True spherical shape-Density: 1.04

  The resin fine particles in the present invention can be used in combination with a plurality of particles described in the section of polymer primary particles for producing core particles obtained by emulsion polymerization. However, in the resin fine particles in the present invention, what is emulsion polymerization? Resins obtained by different polymerization methods can also be used. For such resins, the volume average diameter (Mv) is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more. It is desirable to use one that is usually 3 μm or less, preferably 2 μm or less, more preferably 1 μm or less. Such particles include, for example, particles having the same composition as that obtained by emulsion polymerization, as well as single weights of vinyl monomers such as vinyl acetate, vinyl chloride, vinyl alcohol, vinyl butyral, and vinyl pyrrolidone. Polymers or copolymers, saturated polyester resins, polycarbonate resins, polyamide resins, polyolefin resins, polyarylate resins, polysulfone resins, polyphenylene ether resins and other thermoplastic resins, and unsaturated polyester resins, phenol resins, epoxy resins, Examples thereof include particles made of a thermosetting resin such as a urethane resin and a rosin-modified maleic resin, and two or more of these may be used in combination.

  In order to fuse and stabilize the core particles and the resin fine particles, it is preferable to perform heating (hereinafter, this process is abbreviated as “fusion process”). Of the Tg of the binder resin of the core particles and the Tg of the binder resin of the resin fine particles, the higher the Tg of the fusion process, the higher Tg is preferable, and the temperature higher by 5 ° C. than the higher Tg is particularly preferable. Further, the upper limit is preferably a temperature not higher than 80 ° C. above the Tg, and particularly preferably not higher than 50 ° C. The heating time is not particularly limited, but is preferably 1 to 6 hours.

  By such heat treatment, fusion integration is performed, and toner base particles in which the core particles are coated with the resin fine particle layer are obtained, and the particle shape is also nearly spherical. When the core particles are obtained by an emulsion polymerization aggregation method, heating described later may be performed to fuse the polymer primary particles at the stage of core particle production, but after the resin fine particles are attached to the core particles, It is also preferable to coat the core particles with the resin fine particle layer while simultaneously fusing and integrating the polymer primary particles and other primary particles in the aggregate.

  Before the core particles are coated with the resin fine particles, the core particles can be fused in advance. Also in this case, it is preferable that the core particle is coated with the resin fine particles and then subjected to the fusing process again. It is preferable to fuse the core particles in advance, since the circularity of the core particles is increased, and the resin particles can be uniformly coated on the core particles, so that the blocking resistance, the fixing property and the like are improved.

  The volume average particle size of the toner base particles thus obtained is not particularly limited, but is preferably 3 to 15 μm, particularly preferably 4 to 10 μm, and further preferably 5 to 9 μm. In the present invention, the volume average particle diameter of the toner base particles is an aperture diameter of 100 μm, a particle concentration of 20% by mass, and a count of 50000 by the method described in Examples using Multisizer IIe (manufactured by Beckman Coulter). Defined as measured and determined.

In the toner of the present invention, the surface of the toner base particles produced as described above is further surface-treated with hexaalkyldisilazane (hereinafter abbreviated as “HADS”), and the BET value is 50 to 100 m ² / It is essential that g fine silica particles are adhered. For the first time, it is possible to realize initial and long-term fluidity, reduction of filming and PCR contamination, and stabilization of charge amount.

  The alkyl group of HADS is not particularly limited, but is preferably a methyl group, an ethyl group, a propyl group, or the like, and particularly preferably a methyl group, from the viewpoint of the above effects. That is, as HADS, hexamethyldisilazane (hereinafter abbreviated as “HMDS”) is particularly preferable. Further, different alkyl groups may be simultaneously contained in one molecule of HADS. HADS can be used alone or in combination of two or more.

  Here, the “BET value” means a surface area meter (for example, Flowsorb manufactured by Shimadzu Corp.), preliminarily drying the sample for 30 minutes at 150 ° C. under a nitrogen flow, and then relative of nitrogen to atmospheric pressure. It is defined by a value measured by a nitrogen adsorption BET one-point method using a gas flow method, using a nitrogen helium mixed gas that is accurately adjusted so that the pressure value becomes 0.3.

The BET value of the silica fine particles used in the toner of the present invention is essential to be 50 m ² / g or more, but preferably 70 m ² / g or more. Moreover, although an upper limit is essential 100 m < ² > / g or less, Preferably it is 90 m < ² > / g or less. When silica having a BET value of less than 50 m ² / g is used, the particle diameter of the silica is too large, so that the toner easily separates from the toner base particles, and further moves to the transfer roller. May cause contamination. On the other hand, silica fine particles having a BET value greater than 100 m ² / g may cause a decrease in toner fluidity during long-term use, or may deteriorate the charging characteristics and cause fogging.

Conventionally, silica fine particles between 50 m ² / g and 100 m ² / g could cause deterioration of charging characteristics in long-term use, though not as much as silica fine particles larger than 100 m ² / g. By using toner base particles having a structure in which the surface of the core particles is coated with resin fine particles in the present invention, embedding on the base particles in long-term use is reduced, and this effect is exhibited for the first time.

The problem when using fine silica particles having a BET value of less than 50 m ² / g will be described in more detail. The present invention is particularly suitable for a non-magnetic one-component full-color development system. However, the present invention is not limited to a non-magnetic one-component development system, and the toner is constantly stirred in a developing tank in a cartridge containing the toner. Has been. Since the toner mother particles are rubbed in the stirring step, external additives such as silica fine particles adhering to the toner mother particles with a weak force are detached. When silica fine particles having a BET value of less than 50 m ² / g are used, they may be easily detached because the ratio of the portion of the silica fine particles attached to the toner base particle surface is low. Even if the detachment is avoided here, it comes into contact with the blade for forming the layer, which waits after the transition to the next developer supply roller, and is also subjected to friction here, which also causes the detachment.

Thus, the silica fine particles having a BET value of less than 50 m ² / g that have undergone the desorption in two stages remain separated from the toner even after the toner transfer step (hereinafter referred to as “PC”). It is easy to remain on the drum and is pressed against the drum surface when passing through the next PC cleaning blade, which may cause scratches on the drum surface and may result in filming.

Further, when it comes into contact with the next waiting charging roller, it is attracted to the charging roller, which may cause the surface potential (V ₀ ) of the PC drum to deteriorate to an extremely low potential of about −50 V, for example. This is because, although the surface of the charging roller has a low electric resistance for charging the drum, the attached silica particles have a relatively high electric resistance. The PC drum is usually charged to a potential of, for example, about −700 V by a charging roller, and is lowered to, for example, about −50 V by exposure with a laser or the like during development. This potential and a developer supply of, for example, about −500 V are supplied. The negatively charged toner can be developed by the bias difference with the roller. However, when silica fine particles having a desorbed BET value of less than 50 m ² / g are present, the potential is always lowered, so that unintentional development with a toner on a white background without laser exposure is performed. And this may cause periodic image contamination such as streaks or dots.

Contrary to the above, silica fine particles having a BET value of more than 100 m ² / g may cause fogging due to a decrease in fluidity and a deterioration in charging characteristics during long-term use of the toner. The problem of using only silica fine particles having a BET value greater than 100 m ² / g will be described in more detail.

That is, to contribute significantly to the flowability of the toner, BET value rather than silica fine particles is in the range of 50 to 100 m ² / g, BET value is greater than 100 m ² / g, a so-called small particle size silica. Silica fine particles having a BET value of more than 100 m ² / g are not easily detached, but because of their small size, they are easily embedded in toner mother particles due to long-term friction such as stirring in the developing tank. For this reason, silica fine particles having a BET value greater than 100 m ² / g contributing to fluidity improvement may cause a decrease in fluidity during long-term use of the toner.

On the other hand, the role of the silica fine particles as the external additive is not only to improve the fluidity but also to provide a charging property by a negative charging property higher than that of the toner base particles. In other words, as described above, in the non-magnetic one-component development system, charging is generally given by frictional charging by contact with a blade for forming a layer, and therefore, silica fine particles must be present on the toner surface. Despite being. Silica fine particles having a BET value greater than 100 m ² / g reduce the charging property of the toner base particles to a level equivalent to that of the toner base particles having no silica adhering to the surface by being embedded in the toner surface. A fog may occur.

  Next, surface treatment of silica fine particles used in the toner of the present invention will be described. In the present invention, it is essential to use HMDS treated as the surface treatment of the silica fine particles. Other than this, for example, known polydimethylsiloxane (hereinafter abbreviated as “PDMS”), dimethyldichlorosilane, etc. In some cases, only the fine silica particles that have been subjected to the surface treatment cannot prevent the suction adhesion to the charging roller.

In the present invention, the surface treatment by HADS is not clear about the mechanism that can prevent suction adhesion to the charging roller, but the adhesion to the conductive material usually applied to the surface of the charging roller is weak. This is considered to be the cause. The tendency becomes more of the specific surface area increases, i.e. BET value 50 to 100 m ² / g amount of processing is relatively improved, relative preferably of 60~90m ² / g, a surface treatment by HADS, particularly preferably It is desirable to perform surface treatment with HMDS.

  However, the surface treatment with HADS does not require that the entire amount be treated, and the effect can be obtained when two or more kinds of surface treatments are used in combination. The ratio to the treatment is preferably 50% by mass or more based on the total silica fine particles after being surface-treated with HADS. For example, a combination of PDMS treatment and surface treatment with HADS can be used. As described above, the alkyl group of HADS is not particularly limited, but is preferably a methyl group, an ethyl group, or a propyl group, and particularly preferably a methyl group. In HMDS, two or more different alkyl groups can be used in combination.

In the present invention, 0.05 part by weight or more and 3 parts by weight or less of silica fine particles having a BET value of 50 to 100 m ² / g surface-treated with HADS are attached to 100 parts by weight of toner base particles. It is essential. Preferably it is 0.1 weight part or more, Most preferably, it is 0.3 weight part or more. On the other hand, it is preferably 2 parts by weight or less, particularly preferably 1.5 parts by weight or less.

If the amount of silica fine particles having a BET value of 50 to 100 m ² / g surface-treated with HADS is too small, and instead there are many silica fine particles with a BET value of less than 50 m ² / g, the above-mentioned large particle size silica There may be a problem of using fine particles, and when there are many silica fine particles having a BET value of more than 100 m ² / g, the above-mentioned problem of using fine silica particles may occur. On the other hand, when the adhesion amount of silica fine particles having a BET value of 50 to 100 m ² / g surface-treated with HADS is too large, the effect of preventing PCR contamination of the present invention may not be sufficient.

In the present invention, only the silica fine particles having a BET value of 50 to 100 m ² / g may be used as an external additive. In addition, silica fine particles having a BET value of more than 100 m ² / g are further adhered. This is also preferable in order to improve the fluidity of the toner. In this case, it is preferable that silica fine particles having a BET value larger than 100 m ² / g are adhered in an amount of 0.05 to 2 parts by weight with respect to 100 parts by weight of the toner base particles. The BET value is 100 m ² / g greater than the silica fine particles, further a BET value is 300 meters ² / g or less, crowded buried during a long run of the silica fine particles themselves is preferable in that unlikely. Further, the value of [amount of silica fine particles having a BET value of 50 to 100 m ² / g] / [amount of silica fine particles having a BET value greater than 100 m ² / g] is preferably 1/10 to 10, and 1/2 ~ 2 is particularly preferred.

  Further, the total amount of silica fine particles attached to the toner base particles is preferably 5 parts by weight or less with respect to the toner base particles because there is a limit to the amount that can be attached to the entire surface area of the toner base particles.

  Next, the shape of the toner base particles in the present invention will be described in detail. The average circularity of the toner base particles before external addition is not particularly limited, but is preferably 0.9 or more, particularly preferably 0.92 or more, more preferably 0.94 or more, and the upper limit is preferably 0.00. 99 or less, particularly preferably 0.98 or less, more preferably 0.97 or less. In the emulsion polymerization aggregation method, the average circularity of the toner base particles can be controlled by the temperature and heating time in the fusing step.

The “average circularity” in the present invention is measured as follows and is defined as follows. That is, the toner base particles are dispersed in a dispersion medium (Isoton II, manufactured by Beckman Coulter, Inc.) so as to be in the range of 5720-7140 particles / μL, and a flow type particle image analyzer (Sysmex Corporation (formerly Toa Medical Electronics)). (Manufactured by FPIA 2100), measurement is performed under the following apparatus conditions, and the value is defined as “average circularity”. In the present invention, the same measurement is performed three times, and an arithmetic average value of three “average circularity” is adopted as the “average circularity”.
・ Mode: HPF
-HPF analysis amount: 0.35 μL
-HPF detection number: 2000-2500

The following is measured by the above device and automatically calculated and displayed in the above device, and “circularity” is defined by the following formula.
[Circularity] = [Perimeter of a circle with the same area as the projected particle area] / [Perimeter of projected particle image]
Then, the number of detected HPFs is measured, and the arithmetic average (arithmetic average) of the circularity of each individual particle is displayed on the apparatus as “average circularity”.

When the toner base particle is a perfect sphere, the value is 1. The more complicated the surface shape, the smaller the average circularity. If the average circularity is less than the above range, transfer efficiency may be poor and dot reproducibility may be reduced. In the first place, in the toner base particles having a small average circularity, the silica fine particles enter the recesses on the toner surface, and the effect of the silica fine particles having a BET value of 50 to 100 m ² / g of the present invention cannot be sufficiently obtained. On the other hand, if the range is exceeded, untransferred toner remaining on the PC drum may not be completely scraped off by the blade and may cause image defects.

The present invention is particularly effective in the case of toner base particles having a large average circularity because, for example, toner base particles having irregularities in the shape such as pulverized toner, the shear force during external addition is sufficiently applied. However, it is easy to disperse the external additive. On the other hand, in the case of the toner base particles obtained by the wet method, which is inevitably easy to form toner base particles having a high average circularity, whether it is suspension polymerization or emulsion polymerization aggregation. , It is difficult to apply a shearing force during external addition, and dispersion of the external additive tends to be poor. In particular, when a so-called large particle size silica fine particle having a BET value smaller than 50 m ² / g is externally added, the external additive tends to be poorly dispersed, and the possibility of the above-described separation may increase. If the silica fine particles in the present invention are used, it is difficult to detach, and even if detached, suction adhesion to the charging roller is difficult to occur, so that a more useful effect is exhibited.

  In the present invention, the method for blending and adhering the silica fine particles on the surface of the toner base particles is not particularly limited, and a mixer generally used for toner production can be used. Specifically, it is performed by uniformly stirring and mixing with a mixer such as a Henschel mixer, a V-type blender, a Redige mixer, or a Q-mixer.

  The toner of the present invention can be used for any of black toner, color toner, and full color toner, but when used as a color toner or full color toner, the effects of the present invention can be exhibited more remarkably.

  Further, the toner of the present invention can be used in any system such as a two-component development system or a non-magnetic one-component development system. When used in the two-component development system, the carrier may be a magnetic substance such as iron powder, magnetite powder, ferrite powder or the like, or a resin coating on the surface thereof.

  As described above, the toner of the present invention is preferably used for a non-magnetic one-component development system in which the toner deteriorates when used for a long period of time. In this case, a known member such as stainless steel (SUS) can be used as a charging member such as a charging blade.

  In addition, the toner of the present invention is suitable for so-called medium and high speed machines because the chargeability is stable even after long-term use. That is, it is particularly suitable for a developing method having a developing speed of 80 mm / s or more. Here, “development speed” refers to the speed at which printing paper flows during printing.

  When the development speed is 80 mm / s or more, particularly 100 mm / s or more, the above-described problem becomes more prominent. Therefore, the effect of the specific silica fine particles in the present invention that can solve the problem is further improved. This is preferable because it is easily played. Accordingly, the image forming method for developing an electrostatic charge image using the toner of the present invention at a developing speed of 80 mm / s or more increases the number of printed sheets per unit time and speeds up printing, and further improves the fluidity of the toner. Is an excellent image forming method that is stable for a long period of time, has little filming and PCR contamination due to the removal of silica fine particles, is stable in chargeability, and can suppress an increase in fog.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist. In Examples and Comparative Examples, “parts” means “parts by weight” unless otherwise specified.

Hereinafter, the measurement of the volume average diameter (M _V ) of the polymer primary particles and the colorant is performed as follows, and is defined as that obtained by the measurement method.
<Measurement method of volume average diameter _{(M V)>}
The volume average diameter (M _V ) of the particles having a volume average diameter (M _V ) of less than 1 μm is determined by using Nanotrac 150, manufactured by Nikkiso Co., Ltd., model: Microtrac Nanotrac 150 (hereinafter abbreviated as “Nanotrack”). Use the company's analysis software Microtrac Particle Analyzer Ver10.1.2.-019EE, use ion-exchanged water with an electric conductivity of 0.5 μS / cm as the dispersion medium, and enter the following conditions or the following conditions: And measured by the method described in the instruction manual.

For wax dispersion and polymer primary particle dispersion,
Solvent refractive index: 1.333
-Measurement time: 100 seconds-Number of measurements: 1 time-Particle refractive index: 1.59
-Permeability: Transmission-Shape: True spherical shape-Density: 1.04

For the colorant dispersion,
Solvent refractive index: 1.333
-Measurement time: 100 seconds-Number of measurements: 1 time-Particle refractive index: 1.59
・ Transparency: Absorption ・ Shape: Non-spherical shape ・ Density: 1.00

<Preparation of wax dispersion A1>
Pentaerythritol tetrastearyl ester (H476 manufactured by NOF Corporation, surface tension: 37.4 mN / m, melting point peak 1 temperature 59 ° C., melting point peak 2 temperature 68 ° C., melting peak 1 half-width 9.1 ° C., melting peak 2 half-width 8.5 ° C., crystallization temperature 41 ° C., crystallization peak half width 6.7 ° C.) 30 parts (600 g), 20 mass% sodium dodecylbenzenesulfonate aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd., Neogen S20A) (hereinafter, 2.8 parts (abbreviated as “20% DBS aqueous solution”) and 67.2 parts of demineralized water were heated to 90 ° C. and stirred for 10 minutes using a homomixer (Mark IIf model manufactured by Tokushu Kika Kogyo Co., Ltd.). Then, this dispersion was heated to 90 ° C., using a homogenizer (, 15-M-8PA type) was used to start the circulation emulsification under a pressure condition of 25 MPa, the volume average diameter Nanotrac _{(M V} ) Was measured until the volume average diameter (Mv) reached 250 nm to prepare wax dispersion A1 (emulsion solid content concentration = 30.6 mass%).

<Preparation of polymer primary particle dispersion A1>
42.9 parts of wax dispersion A1 in a reactor (inner volume 21 L, inner diameter 250 mm, height 420 mm) equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device (729.0 g), 336 parts of demineralized water were added, the temperature was raised to 70 ° C. under a nitrogen stream, and 3.2 parts of an 8% by mass hydrogen peroxide aqueous solution and 8% by mass L (+)-ascorbic acid aqueous solution with stirring. 3.2 parts were added all at once.

  After 5 minutes, the following mixture of “monomer” and “emulsifier aqueous solution” and the following “initiator aqueous solution” were added over 4.5 hours, and the mixture of “monomer” and “emulsifier aqueous solution” was added. After completion of dropping, the temperature was raised to 90 ° C. over 30 minutes. Further, the following additional initiator aqueous solution was added over 3 hours, and the internal temperature was maintained at 90 ° C. for 1 hour with further stirring.

[Monomers]
Styrene 76.8 parts (1304.8 g)
Butyl acrylate 23.2 parts Acrylic acid 1.5 parts Tetrachlorobromomethane 0.5 part Hexanediol diacrylate 1.0 part

[Emulsifier aqueous solution]
20% by weight DBS aqueous solution 1.0 part demineralized water 67.3 parts

[Initiator aqueous solution]
8% by mass aqueous hydrogen peroxide solution 12.4 parts 8% by mass L (+)-ascorbic acid aqueous solution 12.4 parts

[Additive initiator aqueous solution]
8% aqueous hydrogen peroxide solution 9.3 parts 8% L (+)-ascorbic acid aqueous solution 9.3 parts

  After the completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion A1. The volume average diameter (Mv) measured by Nanotrac was 200 nm, and the solid content concentration was 18.2% by mass.

<Preparation of polymer primary particle dispersion A2>
In a reactor (inner volume 21 L, inner diameter 250 mm, height 420 mm) equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and each raw material / auxiliary charging device, 2.0 parts of a 20 mass% DBS aqueous solution Then, 317 parts of demineralized water was charged, the temperature was raised to 90 ° C. under a nitrogen stream, and 3.2 parts of an 8% by mass hydrogen peroxide aqueous solution and 3.2 parts of an 8% by mass L (+)-ascorbic acid aqueous solution were stirred. Added all at once.

  5 minutes later, polymerization of a mixture of the following “monomer” and “emulsifier aqueous solution” was started (3.2 parts of 8% by mass aqueous hydrogen peroxide solution, 3.2 parts of 8% by mass L (+)-ascorbic acid aqueous solution). 5 minutes after the batch addition), the solution was added dropwise over 5 hours, and the following initiator aqueous solution was added over 6 hours from the start of polymerization, and further maintained at 90 ° C. for 1 hour with stirring.

[Monomers]
Styrene 88.0 parts (1760.0 g)
Butyl acrylate 12.0 parts Acrylic acid 1.5 parts Tetrachlorobromomethane 0.5 parts Hexanediol diacrylate 0.4 parts

[Emulsifier aqueous solution]
20% by weight DBS aqueous solution 1.5 parts demineralized water 66.4 parts

[Initiator aqueous solution]
8% by mass aqueous hydrogen peroxide solution 18.9 parts 8% by mass L (+)-ascorbic acid aqueous solution 18.9 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion A2. The volume average diameter (Mv) measured with Nanotrac was 115 nm, and the solid content concentration was 19.5 mass%. The dispersion was naturally dried and its Tg was measured by the same method as that for toner Tg. The Tg was 75 ° C.

<Preparation of Colorant Dispersion A>
Carbon black (Mitsubishi Chemical Co., Ltd.) manufactured by a furnace method with a 300 L internal volume equipped with a stirrer (propeller blade) and a toluene extract having an ultraviolet absorbance of 0.02 and a true density of 1.8 g / cm ³ Manufactured by Mitsubishi Carbon Black MA100S) 20 parts (40 kg), 20 parts by weight of DBS aqueous solution 1 part, nonionic surfactant (Eugengen 120 manufactured by Kao), 75 parts of ion-exchanged water having an electric conductivity of 2 μS / cm And predispersed to obtain a pigment premix solution.

The volume average diameter (Mv) of carbon black in the dispersion after premixing measured with Nanotrac was 90 μm. The premix solution was supplied as a raw material slurry to a wet bead mill and subjected to one-pass dispersion. The stator inner diameter was 75 mmφ, the separator diameter was 60 mmφ, the distance between the separator and the disk was 15 mm, and zirconia beads having a diameter of 100 μm (true density 6.0 g / cm ³ ) were used as the dispersing medium. Since the effective internal volume of the stator is 0.5 L and the filling volume of the media is 0.35 L, the media filling rate is 70%. The premix slurry is continuously supplied from the supply port at a supply speed of 50 L / hr by a non-pulsating metering pump, and continuously from the discharge port, with the rotation speed of the rotor being constant (the peripheral speed of the rotor tip is 11 m / sec). By discharging, a black colorant dispersion A was obtained. The volume average diameter (Mv) of the colorant dispersion A measured with Nanotrack was 150 nm, and the solid content concentration was 24.2% by mass.

<Manufacture of toner mother particle A>
A toner was produced by the following procedure using the following components.
Polymer primary particle dispersion A1 95 parts as solids (1092.0 g as solids)
Polymer primary particle dispersion A2 5 parts as solid content
Colorant fine particle dispersion A 6 parts 20% by weight DBS aqueous solution as colorant solids 0.1 part as solids

Polymer primary particle dispersions A1 and 20 were added to a mixer (volume 12 L, inner diameter 208 mm, height 355 mm) equipped with a stirrer (double helical blade), heating / cooling device, concentrating device, and raw material / auxiliary charging device. A mass% DBS aqueous solution was charged and mixed uniformly at an internal temperature of 12 ° C. for 5 minutes. Subsequently, 0.52 parts of FeSO ₄ .7H ₂ O as a 5 mass% aqueous solution of ferrous sulfate was added over 5 minutes at an internal temperature of 12 ° C. while stirring was continued, and then the colorant fine particle dispersion A was added to 5 It was added over a period of time, and the mixture was uniformly mixed while maintaining the internal temperature at 12 ° C., and a 0.5% by mass aqueous solution of aluminum sulfate was added dropwise under the same conditions (the solid content of aluminum sulfate was 0.00% relative to the solid content of the resin. 10 parts).

  Thereafter, the temperature was raised to 50 ° C. over 30 minutes with stirring, and then raised to 51.5 ° C. over 90 minutes. Here, when the volume median diameter (Dv50) was measured using a multisizer, it was 7.2 μm. Thereafter, the polymer primary particle dispersion A2 was added over 7 minutes with stirring and held for 60 minutes, and a 20% by weight DBS aqueous solution (6 parts as a solid content) was added over 10 minutes, and then 20 minutes. The temperature was raised to 70 ° C. over a period of 20 minutes and then further increased to 90 ° C. over a period of 20 minutes. Then, it heated up to 96 degreeC over 30 minutes.

  In the present invention, the volume median diameter (Dv50) of the dispersed particles was measured as follows. In other words, Beckman Coulter Multisizer III (aperture diameter 100 μm) (hereinafter abbreviated as “Multisizer”) is used, and Isoton II made by the company is used as the dispersion medium, so that the dispersoid concentration is 0.03% by mass. It was dispersed in the measurement. The measurement particle size range was from 2.00 to 64.00 μm, and this range was discretized into 256 divisions so as to be equally spaced on a logarithmic scale, and calculated based on statistical values based on their volume.

  Then, the slurry obtained by cooling to 30 degreeC over 20 minutes was extracted, and it suction-filtered with the aspirator using the filter paper of 5 types C (Toyo Filter Paper Co., Ltd. No5C). The cake remaining on the filter paper is transferred to a stainless steel container having an internal volume of 10 L equipped with a stirrer (propeller blade), and 8 kg of ion exchange water having an electric conductivity of 1 μS / cm is added and stirred uniformly at 50 rpm. Thereafter, stirring was continued for 30 minutes.

  Thereafter, the filter paper was suction filtered with an aspirator again using Type 5 C (Toyo Filter Paper No. 5C) filter paper, and the solid matter remaining on the filter paper was again equipped with a stirrer (propeller blade) and had an electrical conductivity of 1 μS / cm. It was transferred to a container with an internal volume of 10 L containing 8 kg of ion-exchanged water, and uniformly dispersed by stirring at 50 rpm and kept stirring for 30 minutes. When this process was repeated 5 times, the electrical conductivity of the filtrate was 2 μS / cm.

  The obtained cake was spread on a stainless steel vat so as to have a height of about 20 mm, and dried in a blow dryer set at 40 ° C. for 48 hours to obtain toner mother particles A.

<Measurement results of shape physical properties of toner base particles A>
The softening point of the toner base particles was 130 ° C., the volume average particle diameter measured by Multisizer IIe was 6.9 μm, and the average circularity was 0.955.

  In the present invention, the toner base particles obtained by drying have a volume average particle diameter of Bocman Coulter Multisizer IIe, 100 μm aperture, and Isoton (ISOTON Coulter Scientific Japan). The toner base particles dispersed in the toner are defined as volume-based volume average particle diameters obtained from the volume distribution of the toner obtained by measurement using the third to 16th channels.

Example 1
The A100 parts of the toner mother particles above, BET measurements ^90m 2 / g of HMDS treated silica (NX90: Nippon Aerosil Co., Ltd.) 1.0 part, BET value 140 m ² / g of HMDS treated silica (H2000: Clariant ) Was added and mixed with a Henschel mixer (Mitsui Mine).

  The obtained toner is an organic photoreceptor charged with a developing rubber roller, a metal blade, a charging roller (PCR) at a printing speed of 100 mm / s, a non-magnetic single component, a guaranteed number of sheets of 6000 sheets (at 5% printing), belt transfer, Using a full color printer equipped with a belt fixing machine using a thermal fixing system, 6000 sheets were continuously printed at a printing rate of 5%.

Example 2
A toner was prepared in the same manner as in Example 1 except that HMDS-treated silica having a BET measurement value of 76 m ² / g was used instead of NX90, and continuous printing was performed in the same manner.

Comparative Example 1
A toner was prepared in the same manner as in Example 1 except that PDMS-treated silica (H05TD: manufactured by Clariant) having a BET measurement value of 40 m ² / g was used instead of NX90, and continuous printing was performed in the same manner.

Comparative Example 2
A toner was prepared in the same manner as in Example 1 except that HMDS / PDMS mixed-treated silica (H05TX: manufactured by Clariant) having a BET measurement value of 42 m ² / g was used instead of NX90, and continuous printing was similarly performed. It was.

Comparative Example 3
A toner was prepared in the same manner as in Example 1 except that HMDS-treated silica (NAX50: manufactured by Nippon Aerosil Co., Ltd.) having a BET measurement value of 47 m ² / g was used instead of NX90, and continuous printing was performed in the same manner.

Comparative Example 4
Continuous printing was performed in the same manner as in Example 1 except that the toner (volume average particle diameter 7.5 μm, average circularity 0.92) produced by the pulverization method was used instead of the toner base particles A.

<Measurement method of fog>
Using an image forming apparatus, the color difference of the white background portion of each standard paper (FC Dream; manufactured by Kishu Paper Co., Ltd.) before and after printing was measured with X-Rite 938 (manufactured by X-Rite). Judging from the size of E, the following criteria were used.
Good fogging: ΔE <1.0
Fog generation: 1.0 ≦ ΔE

<Measurement method of PC filming (image contamination)>
During continuous printing of 6000 sheets at a printing rate of 5% using the above printer, a blank paper image is printed out every 1 kp, and the PC drum surface is checked to check whether image smear due to PC filming has occurred. did.

<Measurement method of PC contamination>
During continuous printing of 6000 sheets at a printing rate of 5% using the printer, an image is printed out every 1 kp, and the surface of the PC charging roller (PCR) is confirmed, and no image smear due to PC filming occurs. Confirmed whether or not.

  The configurations of the toners of Examples 1 and 2 and Comparative Examples 1 to 4 are summarized in Table 1. Table 2 shows the results of continuous printing (evaluation results).

表１中、シリカ微粒子の配合部数は、トナー母粒子１００部に対するシリカ微粒子の配合量（重量部）である。また、「乳化凝集」は、乳化重合凝集法で芯粒子を製造したことを示す。

In Table 1, the number of parts of silica fine particles is the amount (parts by weight) of silica fine particles based on 100 parts of toner base particles. “Emulsion aggregation” indicates that core particles were produced by an emulsion polymerization aggregation method.

From Table 2, in Example 1 and Example 2 using silica fine particles having a BET value of 50 to 100 m ² / g surface-treated with hexaalkyldisilazane, even if continuous printing of 6 kp (6000 sheets) is performed, No fogging, PC filming (image stains) and PCR contamination occurred. On the other hand, in the toners of Comparative Examples 1 to 4, any of fogging, PC filming (image contamination), and PCR contamination occurred.

  The toner having specific silica fine particles attached to specific toner base particles of the present invention stabilizes the fluidity and chargeability of the toner in the developing tank for a long period of time, and does not cause filming due to desorption of silica fine particles. Since there is little contamination to the cartridge member, the function of imparting charging property can be maintained, and the increase in fog can be suppressed, it can be widely used in machines with high developer stress such as high-speed printers and copiers.

Claims (6)

Silica having a BET value of 50 to 100 m ² / g surface-treated with hexamethyldisilazane with respect to 100 parts by weight of toner base particles having a structure in which resin fine particles are coated on the surface of core particles obtained by a wet method Toner comprising 0.05 to 3 parts by weight of fine particles and 0.05 to 2 parts by weight of silica fine particles having a BET value of 100 m ² / g surface-treated with hexamethyldisilazane. .   The toner according to claim 1, wherein the wet method is an emulsion polymerization aggregation method.   The toner according to claim 1, wherein a glass transition point of the binder resin of the resin fine particles is 65 ° C. or higher. Toner mother particles and an average circularity of 0.9 or more as described in any one of claims 1 to claim 3 toner. The toner according to any one of claims 1 to claim 4 nonmagnetic is for one-component developing system. Toner in the developing rate, according to any of claims 1 to claim 5, which is used for more developing scheme 80 mm / s.