JP2007183478A - Non-magnetic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide non-magnetic toner capable of obtaining an image of higher image quality by controlling the mean circularity of toner on rough particle side in the conventional toner, and then, improving the electrification of a toner particle at developing. <P>SOLUTION: Regarding the non-magnetic toner including the toner particle obtained by forming an aggregated particle containing at least a resin particulate and a colorant particle in mixed liquid containing at least the resin particulate and colorant particulate, the peak molecular weight of the binding resin contained in the toner particle is ≤50000, and regarding the number reference particle diameter of the toner particle measured by a flow system particle image measuring apparatus, provided that the mean circularity of the particle group of 10 to 90% particle diameter is expressed by R1, and the mean circularity of the particle group of ≥90% particle diameter is expressed by R2, the relational expressions of 0.950≤R1≤0.965 and 0.970≤R2≤0.990 are satisfied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nonmagnetic toner applied to an image forming apparatus using a one-component developer.

  In an image forming apparatus using an electrophotographic method or an electrostatic recording method, a method of visualizing image information through an electrostatic latent image is currently used in various fields. For example, in electrophotography, an electrostatic latent image is formed on a photoreceptor by an exposure process following a charging process, the electrostatic latent image is visualized with a developer, and image information is reproduced through a transfer and fixing process. . As the developer, there are a one-component developer using a magnetic toner or a non-magnetic toner alone and a two-component developer comprising a toner and a carrier.

  The irregular toner has a different adhesion force to the developing roller or carrier for each toner particle because the adhesion area to the developing roller for a one-component developer and the adhesion area to a carrier for a two-component developer differ for each toner particle. Ease of being different. Since toners having different particle diameters have different developability because of different charge amounts of one toner particle, the toner is selectively developed. Since toner having low developability remains in the developing device, the developability of the image forming apparatus changes with time. In addition, since there are toners that are easy to transfer and toners that are difficult to transfer in the transfer to recording paper, image quality deterioration such as toner scattering and image dropout is likely to occur.

  As a solution to these problems, a resin dispersion in which resin particles of 1 μm or less are dispersed, a colorant and, if necessary, a colorant dispersion in which a release agent particle is dispersed are mixed, and the resin particles, the colorant and the release agent are mixed. An emulsion polymerization aggregation method has been proposed in which agent particles are aggregated to a predetermined toner particle size and then heated to a temperature equal to or higher than the glass transition temperature of the resin to obtain a colored toner in which the aggregates are fused and united.

  In the emulsion polymerization aggregation method, the shape of the toner can be adjusted uniformly, and the particle size distribution can be narrowed. Further, the degree of unevenness can be controlled by controlling the conditions for fusion and coalescence. Moreover, since the release agent particles can be confined inside, the release agent is not exposed to the toner surface. However, toner particles having a large degree of unevenness have a problem that the toner collapses when subjected to mechanical stress in the developing device. Mechanical stress is significant in the one-component contact development method that is becoming mainstream in the market. Therefore, it is necessary to adjust the circularity of the particles and the molecular weight distribution of the resin.

  First, regarding the particle size distribution and circularity of the toner particles by the emulsion polymerization aggregation method, the DB value, which is an index expressing the circularity of the toner base particles, is 0.7 or more and 0.95 or less, or the DB value is 0. It is stated that a toner having a toner content of .95 or less is 10% or more, and that the volume average particle diameter by the Coulter method is 6.5 μm or less can improve the cleaning property or improve the resolution of the output image. (Patent Document 1, Patent Document 2).

  Next, by setting the content of toner particles having a shape factor in the range of 1.2 to 1.6 to 65% by number or more, line image dropout, transfer rate is reduced, and toner fills the member. It has also been mentioned that it is possible to prevent ming (Patent Document 3).

  It has also been proposed to mix non-spherical toner with spherical toner. As for the mixing amount, the number% of spherical toner having a weight average diameter of 2 to 10 μm is 5 to 80%. As a result, the development of the toner is improved by improving the regulation of the toner thin layer (Patent Document 4).

  The following proposals have been made regarding the correlation between the circularity and the physical property values of the resin.

  In the emulsion polymerization aggregation toner used in the two-component development method, by defining a correlation formula between the shape factor of the whole toner and the weight average molecular weight, the toner in the developing machine is prevented from being crushed by the carrier and the cleaning failure is improved. (Patent Document 5).

  In addition, a method for controlling between the average circularity and the molecular weight of the binder resin when an emulsion polymerization aggregation toner is used for one-component jumping development has been proposed (Patent Document 6).

  In addition to the emulsion polymerization aggregation method, the standard deviation (b) of the particle size of the toner particles by the suspension granulation method is 2 μm or less with respect to the correlation between the circularity of the coarse powder having a large particle size and the small fine powder. a-2b) The ratio (C1) between the average circularity (C1) of toner particles having a particle diameter of not less than μm and less than aμm and the average circularity (C2) of toner particles having a particle diameter of not less than aμm and less than (a + 2b) μm / C2) is proposed to be 1.00 to 1.02 (Patent Document 7).

  In any of these proposals, the image quality in the image is improved by defining the particle size distribution and the average circularity. However, it is difficult to improve the average circularity over the entire toner base particles. Further, as a one-component contact developer, the correlation between the average circularity of the toner and the molecular weight of the toner binder resin is not optimized. Therefore, the present invention proposes to improve the chargeability of the toner particles during development by controlling the average circularity of the toner on the coarse powder side in the conventional toner, thereby obtaining a higher quality image.

Japanese Patent Laid-Open No. 2001-22122 JP 2001-27820 A Japanese Patent Laid-Open No. 2002-062585 JP 7-49585 A JP 10-319622 A JP 2001-296684 A Japanese Patent Application Laid-Open No. 2004-299771

  In the emulsion polymerization aggregation toner, the toner surface is uneven to some extent in order to improve the current cleaning property, but the developability on the coarse powder side is inferior. Sharpening the particle size distribution of the toner also leads to improvement in development, but among them, the developability was improved by increasing the circularity on the coarse powder side. In the present invention, it is proposed that the average circularity of the toner on the coarse powder side in the conventional toner is controlled to improve the chargeability of the toner particles in development and obtain a higher quality image.

In particular,
(1) A non-magnetic toner having toner particles obtained by forming aggregated particles containing at least the resin fine particles and the colorant particles in a mixed solution containing at least the resin fine particles and the colorant fine particles, A particle group having a peak molecular weight of 50000 or less contained in the toner particles and having a particle size of 10% to 90% in the number-based particle size measured with a flow particle image measuring device of the toner particles When the average circularity of R1 is R1, and the average circularity of a particle group having a particle size of 90% or more is R2, 0.950 ≦ R1 ≦ 0.965,
0.970 ≦ R2 ≦ 0.990,
A nonmagnetic toner characterized by satisfying the relational expression:
(2) The nonmagnetic toner according to (1), wherein the content of the toner having a number-based particle diameter of 6.5 μm or more measured by a flow type particle image measuring apparatus is 65% by number or less.
(3) The step of classifying the toner particles includes a step in which toner particles having a particle size of 90% or more on the basis of the number of particles measured by a flow type particle image measuring device of the toner particles are heated to be spheroidized or deformed by heating. By using the nonmagnetic toner (1) or (2) obtained by the production method characterized by the above, it is possible to obtain a high-quality image.

  In the emulsion aggregation toner, the toner surface is uneven to some extent in order to improve the current cleaning property, but the developability on the coarse powder side is inferior. Sharpening the particle size distribution of the toner also leads to improvement of development, but in the present invention, the developability was improved by increasing the circularity on the coarse powder side.

  The toner of the present invention is preferably produced by an emulsion polymerization aggregation method. The toner production method starts with a step of granulating particles comprising at least a resin and a colorant in a wet process. Any known wet granulation method can be used as a method for granulating toner particles in the wet state, but a method including a polymerization process such as an emulsion polymerization aggregation method is preferable. In the emulsion polymerization aggregation method, various constituent materials such as a colorant, a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and the mixture is homogenized, sand mill, sand grinder, ultrasonic disperser, etc. Various constituent materials are dissolved or dispersed in the polymerizable monomer. A homomixer or a homogenizer is used in an aqueous medium containing a polymerizable monomer and a dispersion stabilizer in which these various constituent materials are dissolved or dispersed, and dispersed in oil droplets of a desired size as a toner. Thereafter, the stirring mechanism is transferred to a reactor that is a stirring blade described later, and the polymerization reaction is advanced by heating. In this way, toner base material particles are manufactured.

  The resin contained in the toner is not particularly limited as long as it is generally used as a binder in toner. For example, styrene resin, (meth) acrylic resin, olefin resin, polyester resin, amide resin, thermoplastic resin such as carbonate resin, polyether, polysulfone, or epoxy resin, urea resin, urethane resin Thermosetting resins such as these, and copolymers and polymer blends thereof are used. The binder resin used in the present invention includes not only those in a complete polymer state as in, for example, a thermoplastic resin, but also those in an oligomer or prepolymer state as in a thermosetting resin. . Further, the polymer partially includes a prepolymer, a crosslinking agent, and the like.

  As the thermoplastic binder resin constituting the toner, the following polymer of monomers is used. For example, styrenes such as styrene, p-chlorostyrene, α-methylstyrene, vinylnaphthalene, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methacrylic acid , Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, 2-ethylhexyl methacrylate, vinyl unsaturated carboxylic acids such as lauryl methacrylate or esters thereof, and vinyl unsaturated nitriles such as acrylonitrile and methacrylonitrile , Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropyl ketone, ethylene, propylene, butadiene Polymers or copolymers of the two or more monomers, such as olefins like, or mixtures of these polymers. Further, polyester resins, urethane resins, polyamide resins, epoxy resins, cellulose resins, polyether resins (for example, polyoxyoctylene glycol, polyoxide decylene glycol, polyoxyoctadecylene glycol, ethylene oxide adducts of bisphenol A, these Non-vinyl condensation resins such as ester or ether derivatives), mixtures of these resins with the above vinyl polymers or copolymers, and graft copolymers of vinyl polymers can be used. In the case of a vinyl monomer, a binder resin dispersion can be prepared, for example, by emulsion polymerization in an aqueous ionic surfactant solution. In the case of other resins, if the resin is soluble in an organic solvent such as ethyl acetate, acetone, tetrahydrofuran, etc., a homogenizer, etc. together with an aqueous solution in which the resin is dissolved in an organic solvent to dissolve the ionic surfactant or polymer electrolyte The binder resin dispersion can be prepared by dispersing or dissolving the resin particles in water using the dispersing apparatus, and then heating or reducing the pressure to evaporate the organic solvent.

  As the polymerizable monomer constituting the resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decyl Styrene, styrene or styrene derivatives such as pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, Methacrylic acid ester derivatives such as lauryl acrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate, vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as vinyl, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. Examples include vinyl compounds, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers can be used alone or in combination.

  The molecular weight of the binder resin of the toner composed of the polymerizable monomer as described above is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, toner is previously extracted with a THF (tetrahydrofuran) solvent for 20 hours using a Soxhlet extractor. Next, the THF is distilled off using a rotary evaporator, and after further washing with an organic solvent such as chloroform that dissolves the low softening point material but not the outer shell resin, the solution soluble in THF is poured into the pores. Samples filtered through a solvent-resistant membrane filter with a diameter of 0.3 μm were used with 150C manufactured by Waters Co., Ltd., and A-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko Co., Ltd. were connected as standard polystyrene resins. The molecular weight distribution can be measured using the standard curve.

It is desirable that the maximum peak molecular weight is in the range of 5 × 10 ^{3 to} 5 × 10 ⁴ and the THF insoluble content is 5 to 30% by mass. When the maximum peak molecular weight is less than 5,000, the durability is impaired. Conversely, when the maximum peak molecular weight exceeds 50,000, the low-temperature fixability is inferior.

  A polymerizable monomer constituting the resin may be used in combination with those having an ionic dissociation group. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Furthermore, polyfunctionality such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

  In the case of using the emulsion polymerization aggregation method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

  Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Furthermore, those generally used as surfactants such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, higher alcohol sodium sulfate and the like can be used as the dispersion stabilizer.

  Examples of the colorant of the toner of the present invention include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, pyrazolone red, watch tang red, permanent red, and DuPont oil. Red, Resol Red, Lake Red C, Brilliant Carmine 3B, 6B, Rhodamine B Lake, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Pigment, acridine, azine, phthalocyanine, aniline black, azo, azomethine, benzoquinone, ant Quinone dyes, xanthene dyes, dioxazine, thiazine, thiazole, indigo-based, thioindigo dyes, polymethine dyes, diphenylmethane dyes, and various dyes such as triphenylmethane dyes. These pigments and dyes can be used alone or in combination of two or more, and pigments and dyes may be used in combination. As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, 238, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment yellow 14, 17, 74, 93, 94, 138, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, carbon black, etc. can be used, and a mixture thereof can also be used. The number average primary particle size varies depending on the type, but is preferably about 10 to 300 nm.

  In the emulsion polymerization aggregation method, a binder resin dispersion, a pigment dispersion, and a release agent dispersion as necessary are mixed to agglomerate the toner components and unite the aggregates in a uniform mixed state. Therefore, it is possible to obtain a uniform toner composition. Further, by using two or more binder resins having different molecular weights, it is possible to easily control the molecular weight distribution of the toner. In this emulsion polymerization aggregation method, the toner shape can be controlled from an indeterminate shape to a spherical shape by adjusting heating conditions, time, pressure load, and the like.

  However, in the toner particle size distribution, it is difficult to spheroidize the shape of the toner particles having a large particle size in the toner particle emulsification and polymerization processes. Therefore, the spheroidization of toner particles having a large particle diameter in the aggregation and drying process will be taken up. At this time, the average circularity of each toner particle group is used as an index.

The average circularity is used as a simple method for quantitatively expressing the shape of the particles. In the present invention, a flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation is used and the temperature is 23 ° C. and the humidity is 60. Measured in an environment of% RH, particles in a circle equivalent diameter range of 0.60 μm to 400 μm were measured, and the circularity of the particles measured there was expressed by the following equation: Circularity a = L ₀ / L
[In the formula, L0 represents the perimeter of a circle having the same projection area as the particle image, and L represents the particle projection image when image processing is performed with an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter of is shown. ]
Further, for particles having an equivalent circle diameter of 3 μm or more and 400 μm or less, a value obtained by dividing the total circularity by the total number of particles is defined as the average circularity.

  The average circularity used in the present invention is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner particles are perfectly spherical, and the average circularity becomes smaller as the surface shape becomes more complex. After calculating the circularity of each particle, FPIA-2100, which is a measuring apparatus used in the present invention, calculates the circularity of the particles from 0.4 to 1.0 depending on the obtained circularity when calculating the average circularity. A calculation method is used in which the class is divided into 61 classes and the average circularity is calculated using the center value and frequency of the division points.

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more.

  To measure the shape of the toner particles, the flow type particle image measuring device is used, the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 / μl, and 1000 toner particles are obtained. Measure above. After the measurement, this data is used to cut data less than 2 μm, and the average circularity of the toner particles is obtained.

  In the aggregation step, the dispersion is usually mixed at 40 to 60 ° C. for 30 minutes to 3 hours in the presence of an aggregating agent. At this time, the higher the processing temperature and the longer the processing time, the larger the aggregate diameter. As an aggregating agent, an amphoteric surfactant alone or an anionic surfactant and a cationic surfactant are used in combination. The flocculant used is not particularly limited, but those selected from metal salts are preferably used.

  More specifically, monovalent metals such as alkali metal salts such as sodium, potassium and lithium, divalent metals such as alkaline earth metal salts such as calcium and magnesium, divalent metals such as manganese and copper, etc. And salts of trivalent metals such as salt, iron, and aluminum. Specific examples of the salt include sodium chloride, potassium chloride, lithium chloride, calcium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. These may be used in combination.

  In the aggregation state of the toner base material particles, the bonding force between the particles depends to some extent on the particle size of the particles. The smaller the particle size, the greater the bond strength. Particles such as ultrafine powder having a diameter of 1 μm or less even in an agglomerated state in which the mutual bonding force between the toner base particles is relatively weak and can be crushed almost from the joining site by a small external force. The binding force to larger particles in the diameter range is sufficiently large, and even when an external force is applied, there is little possibility that these ultrafine powders will dissociate again.

  The addition amount of the flocculant used in the present invention may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration. In the subsequent coalescence process, the liquid mixture containing aggregates is heated at a temperature equal to or lower than the glass transition temperature and from 30 ° C. to 80 ° C. for 30 minutes to 5 hours. At this time, the higher the processing temperature and the longer the processing time, the more the shape of the aggregate becomes spherical. Conversely, when the temperature is low or the time is shortened, a toner having a low average circularity can be obtained.

  Several methods are conceivable as methods for aggregating the toner base particles. The liquid medium in which the toner base material particles and organic or inorganic fine particles are dispersed is heated at a temperature not lower than the glass transition temperature of the resin contained in the toner base material particles and not higher than the boiling point of the liquid medium. In the production method of the present invention, water-insoluble organic or inorganic fine particles can be added to the toner base particles obtained after the toner base particles are aggregated in the liquid medium.

  In this case, the organic or inorganic fine particles include those that function alone or in plural as charge control agents, fluidizing agents, magnetic particles, offset preventing agents, cleaning aids, and the like. The organic or inorganic fine particles are preferably hydrophobized or hydrophobic from the viewpoint of moisture resistance and charge stability of the obtained toner particles. In addition, by adding a heat-decomposable radical generator such as persulfates to the aggregation process, it is possible to consume unreacted polymerizable monomers and prevent fusion of toner base particle aggregates. it can.

  After completion of the aggregation process, the organic solvent is removed from the toner base particles, and washing and drying are performed. In order to remove the organic solvent, the entire system is gradually heated in a laminar stirring state, and the solvent is removed by applying strong stirring in a certain temperature range. When a dispersant that is soluble in an acid or alkali such as calcium phosphate is used, the calcium phosphate can be decomposed and removed with water using an acid such as hydrochloric acid.

  The toner base particles can be aged by allowing the dispersion of the toner base particles to stand at a constant temperature for a predetermined time either before or after the cleaning / solvent removal step. The temperature of the aging step is preferably 25 ° C. to 100 ° C. above the glass transition temperature of the resin in the toner base particles, and the time is preferably 10 minutes to 12 hours. Before and during the ripening step, an emulsifier is added or the pH of the dispersion of the toner base particles can be raised to suppress the generation of coarse particles in the toner.

  In the production method of the present invention, the drying process of the toner base particles is performed simultaneously with or after the aggregating process as described above. When performed after the classification step, it can be considered as a heat treatment step. The drying step is performed to remove the organic solvent from the obtained toner base particles, and a method of gradually elevating the temperature of the entire system and completely evaporating and removing the organic solvent in the droplets can be employed.

  As the dry atmosphere in which the toner base particles are sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, particularly various air streams heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used are generally used. A spray dryer, belt dryer, rotary kiln, etc. can provide the desired quality in a short time.

  The method for controlling the average circularity of the toner base particles is not particularly limited. Specifically, a method in which toner particles are sprayed in a hot air stream, a method in which toner base particles are repeatedly applied with mechanical energy due to impact force in a gas phase, or a toner flow is added to a solvent that does not dissolve toner base particles and swirling There is a method in which toner base particles having an average circularity adjusted to a desired value are prepared by a method for imparting the toner, and the toner base particles are added to normal toner particles so as to fall within the scope of the present invention. Furthermore, either or both of the temperature and pressure in the drying process are set to be somewhat higher than general drying conditions. Alternatively, in the drying step, there is a method in which a solution containing a non-aqueous solvent that is soluble or swellable with respect to the resin component contained in the toner base material is brought into contact with the toner base material. It is possible to combine several of the above processing methods.

  In the present invention, in order to remove particles having a predetermined particle size from the polymer particles, the toner base particles are classified into an inertia classification type elbow jet (manufactured by Nippon Steel Mining Co., Ltd.), a centrifugal force classification type turboplex (manufactured by Hosokawa Micron Co., Ltd.), TSP. A classification step is carried out using an air classifier such as a separator (manufactured by Hosokawa Micron) or a sieve classifier such as a high-voltage winder (manufactured by Shin Tokyo Machinery Co., Ltd.). Furthermore, by performing this classification process, the toner before the classification process is separated into coarse powder (G powder) having a 90% number average particle diameter as a central particle diameter and toner particles (F powder) excluding it. .

  Incidentally, the G powder generated by classification in the classification process is mixed with the F powder again by improving the average circularity of the toner base particles through the heat treatment process. An external additive is added to the mixed toner base particles to obtain a toner.

When the average circularity of the toner particle group is set in the aggregation process or the drying process, the particle group having a particle diameter of 10% to 90% in the number-based particle diameter measured by the flow particle image measuring apparatus for toner particles When the average circularity of R1 is R1, and the average circularity of a particle group having a particle size of 90% or more is R2, 0.950 ≦ R1 ≦ 0.965,
970 ≦ R2 ≦ 0.990,
It is necessary to satisfy.

  The group of particles having a particle size of 10% to 90% is more easily selectively developed in the toner development process because the chargeability is more stable than the group of toner particles outside the range. Therefore, in the present invention, as described above, the average circularity R2 of 90% particle size or more is higher than the average circularity R1 of the particle group of 10% particle size to 90% particle size, whereby particles of 90% particle size or more are obtained. It has been proposed to improve the chargeability of the group. Since R1 is smaller than R2, one dot is developed and toner consumption is reduced without reducing the laser spot diameter of the scanner with a high-resolution electrophotographic printer. Stabilize. Similarly, it is possible to provide an image forming apparatus capable of obtaining an optimal high-resolution graphic image by suppressing fogging and suppressing a collapse of a grayscale high-density region. Further, when R2 is lower than R1, toner having a particle size of 90% or more is unstable in chargeability and causes image defects such as scattering.

  Further, regarding the correlation between the maximum peak molecular weight of the binder resin of the toner and the average circularity of the toner, when the maximum peak molecular weight of the binder resin exceeds 50000, the toner is mechanically contained in the developing machine. When crushed by the action, the crushed toner is easily fused to the photosensitive member and the toner regulating member. The toner fusing of the developing unit causes streaks in the image.

  Since it is conceivable that the toner particle size will be reduced in order to improve the image quality, the toner particle size measured by the flow type particle image measuring device is 6.5 μm or more and 65% by number or less. Is desirable. At that time, in order to ensure the charging uniformity of the toner particles, it is necessary to limit the content of the toner particles larger than the center particle diameter.

  Further, the toner base particles of the present invention can be subjected to an external addition step after drying and classification steps. The toner can be obtained by adhering organic and inorganic fine particles to the toner base particles with a mixer or the like. As the mixer used in the external addition step, a high-speed stirring type mixer such as a Henschel mixer or a super mixer can be used.

  The present invention is preferably applied to toner of a one-component developer constituting the developer. The developer of the present invention is excellent in fluidity, blade cleaning properties, environmental stability, and charge stability. In the developing system that uses a one-component developer and regulates a thin layer of toner, there is an effect that it is easy to control the amount of toner on the sleeve with a blade. Hereinafter, the present invention will be described using examples.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this does not limit this invention at all. In addition, the number of parts in the following composition is part by mass unless otherwise specified. In Examples and Comparative Examples, yellow, cyan, magenta, and black were synthesized, but improvement in developability was confirmed by changing the black formulation.

<Example 1>
(Wax dispersion)
70 parts of demineralized water, an ester mixture mainly composed of behenyl behenate (Unistar M2222SL, manufactured by Nippon Oil & Fats) and an ester mixture mainly composed of stearyl stearate (Unistar M9676, manufactured by Nippon Oil & Fats) 30 parts of a mixture of 7: 3, dodecylbenzene 2 parts of sodium sulfonate (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., active ingredient 66%) were mixed and emulsified by applying high-pressure shearing at 90 ° C. to obtain a dispersion of ester wax fine particles.

(Polymer primary particle dispersion)
A reactor equipped with a stirrer (full zone blade), heating / cooling device, concentrating device, and each raw material / auxiliary charging device was charged with 45 parts of wax dispersion-1 and 400 parts of demineralized water and heated to 90 ° C. under a nitrogen stream. The temperature was raised, and 1.5 parts of an 8% aqueous hydrogen peroxide solution and 1.5 parts of an 8% aqueous ascorbic acid solution were added. Thereafter, the following monomers and initiator were added, and emulsion polymerization was performed for 7 hours.

[Monomers]
Styrene 78 parts butyl acrylate 22 parts acrylic acid 3 parts octanethiol 0.4 part 2-mercaptoethanol 0.01 part hexanediol diacrylate 1 part [emulsifier aqueous solution]
15% Neogen SC aqueous solution 1 part Demineralized water 25 parts [Initiator aqueous solution]
8% hydrogen peroxide aqueous solution 9 parts 8% ascorbic acid aqueous solution 9 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer dispersion.

(Resin fine particle dispersion)
A reactor equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and a raw material / auxiliary charging device was charged with 5 parts of a 15% neogen SC aqueous solution and 372 parts of demineralized water, and 90 ° C. under a nitrogen stream The temperature was increased to 1.6 parts of an 8% aqueous hydrogen peroxide solution and 1.6 parts of an 8% aqueous ascorbic acid solution. Thereafter, a mixture of the following monomers / emulsifier aqueous solution was added over 5 hours from the start of polymerization, and an initiator aqueous solution was added over 6 hours from the start of polymerization, and the mixture was further maintained for 30 minutes.

[Monomers]
Styrene 88 parts butyl acrylate 12 parts acrylic acid 2 parts bromotrichloromethane 0.5 part 2-mercaptoethanol 0.01 part hexanediol diacrylate 0.4 part [emulsifier aqueous solution]
15% Neogen SC aqueous solution 2.5 parts Demineralized water 24 parts [Initiator aqueous solution]
8% hydrogen peroxide aqueous solution 9 parts 8% ascorbic acid aqueous solution 9 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer dispersion.

[Manufacture of developing toner]
105 parts of polymer primary particle dispersion (as solids)
Resin fine particle dispersion 5 parts (as solid content)
Charge control agent Bontron E-84 (5% dispersion manufactured by Orient Chemical Co.) 1 part (as solid content)
Carbon black (Cabot, Regal 330R) 7 parts (as solids)
0.5 parts of 15% Neogen SC aqueous solution (as solids)

  Using each of the above components, a toner was produced by the following procedure.

(Aggregation process)
The mixture was heated to 40 ° C. while being dispersed and stirred with a disperser and held for 3 hours, then adjusted to pH = 7, heated to 95 ° C. and held for 2 hours. Thereafter, the resulting slurry of toner base material particles was cooled, filtered with a Kiriyama funnel, washed with water, and dried with a blow dryer at 45 ° C. for 10 hours to obtain toner particles. The toner particles obtained by the above method have a number average particle size of 6.15 μm as measured by a flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation (after this, the particle size is determined by a flow type particle image analyzer. And).

(Classification / heat treatment process)
Since the 90% particle size at this time is 10 μm, the toner particles are classified with an elbow jet (manufactured by Nittetsu Mining Co., Ltd.) so as to obtain G powder having a central particle size of 10 μm. separated. Next, the G powder is subjected to a heat treatment step at 60 ° C. for 1 hour in a nitrogen atmosphere using a spray dryer, and after cooling, is mixed with the F powder to obtain black toner base particles. Black toner 1 was obtained by mixing 1.5 parts of silica (R972 manufactured by Aerosil Co., Ltd.) with 100 parts of black toner base particles using a Henschel mixer (Mitsui Miike Co., Ltd.).

  The black toner 1 finally obtained has a 10% particle diameter of 2.5 μm and a 90% particle diameter of 10 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.957, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.981. The number content of the toner particle group of 6.5 μm or more is 60%. Furthermore, the maximum peak molecular weight of THF soluble matter by GPC is 45000.

(Colorant fine particle dispersion-1)
C. I. 20 parts of Pigment Yellow 74, 7 parts of polyoxyethylene alkylphenyl ether, and 73 parts of demineralized water were dispersed in a sand grinder mill to obtain a colorant fine particle dispersion.

(Colorant fine particle dispersion-2)
C. I. 20 parts of Pigment Red 238, 2.5 parts of alkylbenzene sulfonate, and 77.5 parts of demineralized water were dispersed by a sand grinder mill to obtain a colorant fine particle dispersion.

  Instead of carbon black, each of Colorant Fine Particle Dispersion-1, Colorant Fine Particle Dispersion-2, and Pigment Blue 15: 3 (“EP-700 Blue GA” manufactured by Dainichi Seika Kogyo Co., Ltd.) is used. Cyan toner 1 and magenta toner 1 were obtained.

<Example 2>
Under the toner production conditions of Example 1, the black toner 2 was obtained without change except that the reaction temperature of the aggregation step for 3 hours at 40 ° C. was changed to 70 ° C. The black toner 2 has a 10% particle size of 3.1 μm and a 90% particle size of 11.2 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.958, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.982. The number content of the toner particle group of 6.5 μm or more is 70%. The maximum peak molecular weight of THF soluble matter by GPC is 46000.

<Example 3>
Under the toner production conditions of Example 1, a black toner 3 was obtained without change except that the heat treatment step was not performed and 95 ° C. was maintained for 4 hours in the aggregation step. The black toner 3 has a 10% particle diameter of 2.4 μm and a 90% particle diameter of 10.2 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.957, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.971. The number content of the toner particle group of 6.5 μm or more is 55%. Moreover, the maximum peak molecular weight of THF-soluble matter by GPC is 47000.

<Comparative Example 1>
The black toner 4 was obtained without change except that the toner production conditions of Example 1 were changed to 1 part of hexanediol acrylate at the time of preparing the resin fine particle dispersion. The black toner 4 has a 10% particle size of 2.3 μm and a 90% particle size of 9.8 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.958, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.983. The number content of the toner particle group of 6.5 μm or more is 59%. The maximum peak molecular weight of THF soluble matter by GPC is 61000.

<Comparative example 2>
Black toner 5 was obtained without change except that the amount of the polymer primary particle dispersion added during the aggregation process was 80 parts under the toner production conditions of Example 1. The black toner 5 has a 10% particle size of 2.5 μm and a 90% particle size of 10.1 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.977, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.982. The number content of the toner particle group of 6.5 μm or more is 55%. Moreover, the maximum peak molecular weight of THF-soluble matter by GPC is 47000.

<Comparative Example 3>
Black toner 6 was obtained without change except that the heat treatment step was not performed under the toner production conditions of Example 1. The black toner 6 has a 10% particle size of 2.4 μm and a 90% particle size of 10.2 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.957, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.941. The number content of the toner particle group of 6.5 μm or more is 70%. Moreover, the maximum peak molecular weight of THF-soluble matter by GPC is 47000.

<Comparative example 4>
Under the toner production conditions of Example 2, the black toner 7 was obtained without change except that 95 ° C. was maintained for 4 hours in the aggregation process. The black toner 7 has a 10% particle size of 3.2 μm and a 90% particle size of 10.9 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.98, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.991. The number content of the toner particle group of 6.5 μm or more is 71%. The maximum peak molecular weight of the THF soluble component by GPC is 58,000.

<Comparative Example 5>
Black toner 8 was obtained without change except that the heat treatment step was not performed under the toner production conditions of Comparative Example 1. The black toner 8 has a 10% particle size of 2.4 μm and a 90% particle size of 10.2 μm. The average circularity R1 of the particle group having a particle size of 10% to 90% was 0.978, and the average circularity R2 of the particle group having a particle size of 90% or more was 0.938. The number content of the toner particle group of 6.5 μm or more is 70%. Moreover, the maximum peak molecular weight of the THF soluble part by GPC is 57000.

{Image evaluation}
Using a predetermined toner for Examples 1 to 3 and Comparative Examples 1 to 5 shown in Table 1, the toner was filled in a developing unit of LBP 5700 (manufactured by Canon Inc.), and various image evaluations were performed. The results are shown in Table 2. The density conditions were adjusted so that the gray scale and color patches made by Kodak Co., Ltd. were used as the original, and the gray scale was reproduced as faithfully as possible in the full-color copy image, and the density was adjusted so that the maximum density of the single color copy was 1.1 or more. .

1) Lines on image Using a chart with a printing rate of 2%, a printing durability test of 15,000 sheets was performed, and it was visually checked whether vertical stripes in a halftone image were generated.
A: There are no streaks.
B: There is one streak.
C: There are 2 to 5 streaks.
D: There are many streaks.

2) Line images The images were visually evaluated for fine line reproducibility and gradation reproducibility (the number of gray scale reproduction steps of Eastman Kodak Company) of the line images, and ranked as follows.
A: The line image is not crushed or missing, and the gray scale reproduction stage number can be discriminated by 7 or more stages.
B: Although the line image is slightly crushed and missing, there is no practical problem and the number of reproduction stages is 5 to 6.
C: The line image is crushed and missing and becomes discontinuous, or the number of reproduction stages is 4 or less.
D: Unbearable for use.

3) Evaluation of cleaning property 300 sheets were continuously fed using a chart with a printing rate of 25%, and the presence or absence of cleaning failure of the toner on the photoreceptor was judged on the image, and ranked as follows.
A: No toner fusion on the photoreceptor.
B: A toner fused slightly on the photoconductor but does not appear on the image.
C: A toner fusion appears on the photoreceptor as noise on the image.
D: Unbearable for use.

Claims (3)

A non-magnetic toner having toner particles obtained by forming aggregated particles containing at least the resin fine particles and the colorant particles in a mixed solution containing at least the resin fine particles and the colorant fine particles,
Particles having a maximum peak molecular weight of the binder resin contained in the toner particles of 50000 or less and having a particle size of 10% to 90% in the number-based particle size measured by the flow type particle image measuring device of the toner particles When the average circularity of the group is R1, and the average circularity of the particle group having a particle size of 90% or more is R2, 0.950 ≦ R1 ≦ 0.965,
0.970 ≦ R2 ≦ 0.990,
A nonmagnetic toner characterized by satisfying the relational expression:   2. The nonmagnetic toner according to claim 1, wherein the content of the toner having a number-based particle diameter of 6.5 μm or more measured by a flow type particle image measuring apparatus is 65% by number or less.   In the toner particle classification step, the toner particles are obtained by a production method comprising a step of heat spheroidizing or heat deforming toner particles having a particle size of 90% or more based on the number of particles measured by a flow particle image measuring device of the toner particles. The nonmagnetic toner according to claim 1, wherein the nonmagnetic toner is a toner.