JP5629658B2 - Electrostatic latent image developing toner, toner set, and method for producing electrostatic latent image developing toner - Google Patents

Description

  The present invention relates to an electrostatic latent image developing toner, a toner set, and a method for producing an electrostatic latent image developing toner.

  In general, in electrophotography, a latent image carrier made of a photoconductive photoreceptor is charged by corona charging or the like, the latent image carrier is exposed by a laser, LED, etc., and the formed electrostatic latent image is toner or the like. The developer is visualized and a high quality image is obtained. In general, as a toner to be applied to these developing methods, a thermoplastic resin as a binder is mixed with a dye, a pigment or a release agent as a colorant or a charge control agent, and, for example, small particles are obtained by a method such as kneading, pulverization, or classification. Toner having a particle size is used. In general, inorganic fine powders such as silica and titanium oxide are added in order to impart fluidity to the toner, to control charging of the toner, and to improve cleaning properties.

  Due to the increasing demand for higher image quality in recent years, the particle size of toner has been reduced to, for example, about 5 to 10 μm. The fine line reproducibility is improved by reducing the particle size of the toner.

  In addition to the demand for higher image quality, as the image forming apparatus increases in speed and energy saving, a toner having excellent low-temperature fixability is desired. When preparing a toner excellent in low-temperature fixability, a polyester resin is widely used as a binder (binder resin), and a toner having a small particle diameter using a polyester resin as a binder resin is widely used. .

  However, the toner having a small particle diameter has a problem that the small particle diameter easily passes through a device for removing transfer residual toner on the latent image carrier, such as an elastic blade, provided in the cleaning unit. If untransferred toner passes through the apparatus, it causes image defects.

  In order to solve such a problem of a small particle diameter toner using a polyester resin as a binder resin, for example, a toner having an aspect ratio of 0.8 to 0.9 has been proposed (Patent Document 1).

JP 2009-134079 A

Certainly, according to the toner described in Patent Document 1, since the aspect ratio of the toner is set to be low, the toner particles are difficult to roll on the surface of the latent image carrying portion, and the problem of slipping through the cleaning portion of the transfer residual toner occurs. Hateful. However, since the toner described in Patent Document 1 has a low toner aspect ratio, the toner particles may be difficult to peel off from the surface of the latent image carrier.
In such a case, an image defect called “missing” tends to occur in the formed image.

  Further, the toner described in Patent Document 1 has a large specific surface area due to a small particle diameter. For this reason, in the toner described in Patent Document 1, the release agent is likely to be exposed on the surface of the toner particles. Here, the release agent is blended in the binder resin for the purpose of improving the release property between the fixing roller and the recording medium on which the image is formed, and the amount of the release agent used is increased. As a result, a toner having excellent releasability can be obtained. However, in a toner having a small particle size, since the amount of the release agent exposed on the toner surface is large, the release agent is easily dropped from the toner surface due to an impact applied during the production of the toner. For this reason, the toner having a small particle size has a problem that it is difficult to stabilize the content of the release agent of the binder resin or to highly charge the release agent in the binder resin. For this reason, the toner described in Patent Document 1 may be inferior in releasability.

  Furthermore, for toners with small particle diameters where a large amount of the release agent is exposed on the toner surface, the release agent is softened and melted by heat applied by frictional heat during drying or grinding, etc. There is a problem that the release agent tends to ooze out on the toner surface. When the release agent oozes out, when the toner is stored at a high temperature, aggregation or the like occurs, or when forming an image, an image defect due to adhesion of the toner to the developing sleeve may occur in the formed image. .

  The problem with these release agents is that in the so-called pulverized toner obtained by mixing and kneading the binder resin and various components such as a colorant and a release agent, and then pulverizing and classifying the kneaded product. It is remarkable. This is because the pulverized toner is subjected to a large mechanical stress and a large amount of frictional heat in the pulverization process.

  Further, when a color image is formed by the electrostatic latent image developing toner, it usually comprises a black electrostatic latent image developing toner and, for example, three color toners of yellow, cyan, and magenta. A toner set is used. However, in a toner having a small particle diameter using a polyester resin as the binder resin, it is difficult to stabilize the content of the release agent contained in the binder resin due to the above-described problem. For this reason, when an image is formed using a conventional toner set, an image formed by four color toners having different contents of the release agent in the binder resin is fixed at the same temperature. The gloss (gloss) of the image after fixing varies, and the image quality of the formed image is likely to deteriorate due to uneven gloss.

  The present invention has been made in view of such circumstances, and is excellent in releasability between a fixing roller and a recording medium on which an image is formed, and in a formed image, an image defect due to adhesion of toner to a developing sleeve, An object of the present invention is to provide a toner for developing an electrostatic latent image having a small particle diameter using a polyester resin as a binder resin, which can suppress image defects due to toner passing through in a cleaning section and image defects such as voids. .

  Another object of the present invention is to provide a toner set including the above-described toner for developing an electrostatic latent image, which can suppress a deterioration in image quality of a formed image due to gloss unevenness.

  Another object of the present invention is to provide a method for producing a toner for developing an electrostatic latent image, which is suitable as a method for producing the toner for developing an electrostatic latent image.

  The present inventors are an electrostatic latent image developing toner (hereinafter also referred to as toner) containing at least a colorant and a release agent in a binder resin, the binder resin being a polyester resin, The average circularity is 0.960 to 0.975, and the endothermic amount of the toner at the time of melting of the release agent measured by a differential scanning calorimeter is 10.0 to 15.0 J / g. The present inventors have found that the above-described problems relating to toner can be solved by an electrostatic latent image developing toner that is confirmed by observing toner with an electron microscope and has a small number of toner particles that exude on the surface of the release agent. The invention has been completed.

  In addition, the present inventors set the maximum value of the endothermic amount at the time of melting of the release agent measured by the differential scanning calorimeter in the toner set from four colors to the four types of toner included in the toner set. It has been found that when the difference from the minimum value is 0.5 J / g or less, the above-described problems relating to the toner set for forming a color image can be solved, and the present invention has been completed.

  Furthermore, the present inventors have mixed the binder resin, and at least the colorant and the release agent, and then melt-kneaded, and after roughly pulverizing the obtained melt-kneaded product to a predetermined diameter, It was found that an electrostatic latent image developing toner capable of solving the above-described problems related to the toner can be obtained by subjecting the heat-treated product to heat treatment and finely pulverizing the heat-treated coarsely pulverized product.

  More specifically, the present invention provides the following.

(1) An electrostatic latent image developing toner containing at least a colorant and a release agent in a binder resin,
The binder resin is a polyester resin;
The electrostatic latent image developing toner has an average circularity of 0.960 to 0.975,
In the electrostatic latent image developing toner, the endothermic amount at the time of melting of the release agent measured by a differential scanning calorimeter is 10.0 to 15.0 J / g,
100 or more electrostatic latent image developing toner particles contained in an image taken at a magnification of 3000 times with a scanning electron microscope are confirmed by observing the image taken at a magnification of 10,000 times. The electrostatic latent image in which the ratio of the number of particles of the electrostatic latent image developing toner that has exuded on the surface to the number of particles of the electrostatic latent image developing toner to be observed is 10% by number or less Development toner.

(2) The electrostatic latent image developing toner according to (1), produced by a method comprising the following steps (I) to (IV):
(I) a step of melt-kneading the binder resin and at least the colorant and the release agent after mixing;
(II) A step of roughly pulverizing the melt-kneaded product obtained in step (I) to obtain a coarsely pulverized product having a volume average particle diameter of 15 to 25 μm;
(III) a step of heat-treating the coarsely pulverized product; and (IV) a step of obtaining a toner having a volume average particle diameter of 5 to 10 μm by finely pulverizing the coarsely pulverized product that has been heat-treated.

(3) The electrostatic latent image developing toner according to (1) or (2), wherein the colorant is a colorant of black and three other hues of black, each having a different hue. A toner set containing
The difference between the maximum value and the minimum value of the endothermic amount at the time of melting of the release agent measured by a differential scanning calorimeter in the four types of toner for developing an electrostatic latent image included in the toner set is 0.5 J. / G or less, a toner set.

(4) A method for producing a toner for developing an electrostatic latent image, which contains at least a colorant and a release agent in a binder resin,
The binder resin is a polyester resin;
A method for producing a toner for developing an electrostatic latent image, comprising the following steps (I) to (IV):
(I) a step of melt-kneading the binder resin and at least the colorant and the release agent after mixing;
(II) A step of roughly pulverizing the melt-kneaded product obtained in step (I) to obtain a coarsely pulverized product having a volume average particle diameter of 15 to 25 μm;
(III) a step of heat-treating the coarsely pulverized product; and (IV) a step of obtaining a toner having a volume average particle diameter of 5 to 10 μm by finely pulverizing the coarsely pulverized product that has been heat-treated.

  According to the present invention, the releasability between the fixing roller and the recording medium on which the image is formed is excellent, and in the formed image, the image is defective due to toner adhesion to the developing sleeve, and the image is caused by the toner slipping through the cleaning unit. Provided are a toner for developing an electrostatic latent image having a small particle diameter using a polyester resin as a binder resin, and a method for producing the toner for developing an electrostatic latent image, which can suppress image defects such as defects and voids. The

  In addition, according to the present invention, there is provided a toner set including the above-described toner for developing an electrostatic latent image, which can suppress deterioration in image quality of a formed image due to gloss unevenness.

It is a figure which shows the typical example of the DSC curve of a toner. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

[First Embodiment]
The toner for developing an electrostatic latent image according to the first embodiment includes at least a colorant and a release agent in a binder resin, the binder resin is a polyester resin, and the average circularity of the toner is 0.960. To 0.975, and the endothermic amount of the release agent measured by a differential scanning calorimeter in the toner is 10.0 to 15.0 J / g, and the toner is observed with a scanning electron microscope. The toner for electrostatic latent image development, which is confirmed, has a small number of toner particles that have been exuded on the surface of the release agent that has exuded on the surface.

  The electrostatic latent image developing toner according to the first embodiment may include a charge control agent and magnetic powder in the binder resin as desired. In addition, the electrostatic latent image developing toner according to the first embodiment is obtained by attaching an external additive to the surface of toner base particles in which various components are blended with a binder resin, if desired. There may be. Furthermore, the electrostatic latent image developing toner according to the first embodiment can be mixed with a carrier and used as a two-component developer, if desired. Hereinafter, for the electrostatic latent image developing toner according to the first embodiment, a binder resin, a colorant, a release agent, a charge control agent, magnetic powder, and a carrier, and a method for producing the electrostatic latent image developing toner, The image forming method using the electrostatic latent image developing toner will be described in order.

[Binder resin]
In the electrostatic latent image developing toner according to the first embodiment, a polyester resin is used as the binder resin. When a polyester resin is used as the binder resin, it is easy to prepare a toner that can be satisfactorily fixed at a low temperature and has excellent color developability. The polyester resin used as the binder resin is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from the polyester resins conventionally used as the binder resin for toner.

  Hereinafter, specific examples of the polyester resin will be described. As the polyester resin, those obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component can be used. Examples of the components used when synthesizing the polyester resin include the following divalent or trivalent or higher alcohol components and divalent or trivalent or higher carboxylic acid components.

  Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, Bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Entaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include trivalent or higher alcohols such as butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Divalent carboxylic acids such as acids, isododecyl succinic acid, isododecenyl succinic acid and the like or alkyl or alkenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid Acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphtha Tricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid , Tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, emporic trimer acid, and other trivalent or higher carboxylic acids. These divalent or trivalent or higher carboxylic acid components may be used as ester-forming derivatives such as acid halides, acid anhydrides, and lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  When the binder resin is a polyester resin, the softening point of the polyester resin is preferably 80 to 150 ° C, and more preferably 90 to 140 ° C.

  A crosslinking agent and a thermosetting resin can be added to the polyester resin as long as the object of the present invention is not impaired. By introducing a partially cross-linked structure into the polyester resin, which is a binder resin, the storage stability, shape retention, durability, etc. of the toner can be improved without deteriorating the fixability.

  As the thermosetting resin that can be used together with the polyester resin, for example, an epoxy resin or a cyanate resin is preferable. Specific examples of suitable thermosetting resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins, cyanate resins and the like. It is done. These thermosetting resins can be used in combination of two or more.

  The glass transition point (Tg) of the binder resin is preferably 50 to 65 ° C, and more preferably 50 to 60 ° C. When the glass transition point of the binder resin is too low, the toner may be fused inside the developing part of the image forming apparatus or the storage stability of the toner may be reduced, so that the toner container may be transported or stored in a warehouse. In some cases, the toner may be partially fused. In addition, when the glass transition point of the binder resin is too high, the strength of the binder resin is reduced, and the toner is likely to adhere to the latent image carrying portion. When the glass transition point of the binder resin is too high, the toner tends to be difficult to fix well at a low temperature.

  In addition, the glass transition point of a polyester resin can be calculated | required from the change point of specific heat using a differential scanning calorimeter (DSC). More specifically, it can be determined by measuring an endothermic curve using a differential scanning calorimeter DSC-6200 manufactured by Seiko Instruments Inc. as a measuring device. An endothermic curve obtained by placing 10 mg of a measurement sample in an aluminum pan, using an empty aluminum pan as a reference, and measuring at a measurement temperature range of 25 to 200 ° C. and a temperature increase rate of 10 ° C./min. The glass transition point can be obtained more.

[Colorant]
The toner for developing an electrostatic latent image contains a colorant in a binder resin. As the colorant contained in the electrostatic latent image developing toner, a known pigment or dye can be used in accordance with the color of the toner particles. Specific examples of suitable colorants to be added to the toner include black pigments such as carbon black, acetylene black, lamp black, and aniline black; yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow , Yellow pigments such as Navels Yellow, Naphthol Yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake; Red Yellow Yellow Lead, Molybdenum Orange, Permanent Orange Orange pigments such as GTR, Pyrazolone Orange, Vulcan Orange, Indanthrene Brilliant Orange GK; Bengala, Cadmium Red, Lead Tan, Mercury Cadmium, Permanent Red 4R, Lithium Red pigments such as Lured, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B; Purple such as Manganese Purple, Fast Violet B, Methyl Violet Lake Pigment: Blue pigment such as bitumen, cobalt blue, alkali blue lake, Victoria blue partially chlorinated, First Sky Blue, Indanthrene Blue BC; Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Final Yellow Green G Green pigments; white pigments such as zinc white, titanium oxide, antimony white, zinc sulfide; barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white, etc. It includes the quality pigments. These colorants may be used in combination of two or more for the purpose of adjusting the toner to a desired hue.

  The amount of the colorant used is not particularly limited as long as the object of the present invention is not impaired. Specifically, 1-10 mass parts is preferable with respect to 100 mass parts of binder resin, and 3-7 mass parts is more preferable.

〔Release agent〕
The electrostatic latent image developing toner according to the first embodiment improves the releasability between the fixing roller and the recording medium on which the image is formed, and provides offset and image smearing in the formed image (when the image is rubbed). A mold release agent is included for the purpose of suppressing the occurrence of stains around the image.

  The melting point of the release agent is not particularly limited as long as the object of the present invention is not impaired, but 60 to 90 ° C. is preferable. If the melting point of the release agent is too high, depending on the fixing temperature, it may be difficult to satisfactorily fix the toner on the recording medium. When the melting point of the release agent is too low, the release agent easily oozes out on the toner surface, and when stored at a high temperature, the toner aggregates or an image defect occurs in the formed image due to the toner adhering to the developing sleeve. It becomes easy.

  The mold release agent is preferably a wax, and examples of the wax include polyethylene wax, polypropylene wax, fluororesin wax, Fischer-Tropsch wax, paraffin wax, ester wax, montan wax, rice wax and the like. These release agents can be used in combination of two or more. By adding such a release agent to the toner, it is possible to more effectively suppress the occurrence of offset and image smearing (dirt around the image when the image is rubbed) in the formed image.

  The toner according to the first embodiment is excellent in releasability between the fixing roller and the recording medium on which the image is formed because the amount of wax in the binder resin is increased. Whether or not a predetermined amount of the release agent is dispersed in the binder resin is determined by the amount of heat absorbed when the release agent contained in the toner is melted by a differential scanning calorimeter (DSC) using the toner as a sample (J / G) and confirmation of the amount of toner particles in the toner that have exuded the release agent on the surface using a scanning electron microscope (SEM).

  When the endothermic amount at the time of melting of the release agent contained in the toner measured by DSC is 10.0 to 150 J / g, the releasability between the fixing roller and the recording medium on which the image is formed is excellent. The toner contains a sufficient amount of release agent to obtain the toner. If the amount of heat absorbed during the melting of the release agent contained in the toner is excessive, the storage stability decreases due to the fusion between the toners, or the release agent oozes out from the toner surface, leading to the toner developing sleeve. There is a tendency for image defects to occur in the formed image due to the adhesion.

  However, even if the endothermic amount at the time of melting of the release agent contained in the toner is within the above-described preferable range, if the release of the release agent to the toner surface occurs in the toner, the release agent contained in the toner The total amount of the agent does not contribute to the improvement of the releasability of the toner, and a toner having a desired releasability may not be obtained.

  For this reason, in order to prepare a toner having a desired release property by filling a predetermined amount of the release agent in the binder resin, it is possible to suppress the release of the release agent from the toner surface in the toner. There is a need to.

  The amount of heat absorbed when the release agent contained in the toner melts usually varies depending on the amount of the release agent contained in the toner. For this reason, the amount of heat absorption at the time of melting of the release agent contained in the toner can be adjusted by increasing or decreasing the amount of the release agent used when preparing the toner. The amount of the release agent used is not particularly limited as long as the endothermic amount at the time of melting of the release agent contained in the toner can be within a predetermined range, but typically, when the total mass of the toner is 100 parts by mass It is preferable that it is 5-8 mass parts. When the amount of the release agent used is too small, there is a tendency that offset property and image smearing cannot be effectively prevented. On the other hand, when the amount exceeds 8 parts by mass, the toners are fused together. Storage stability tends to decrease.

  Further, according to the preferred method for producing the toner according to the first embodiment, which will be described later, the heat-treated coarsely pulverized product having a high degree of circularity is finely pulverized. It is possible to suppress the release of the release agent on the surface, and the release of the release agent to the toner surface due to softening and melting of the release agent.

  The DSC measurement method for the endothermic amount at the time of melting of the release agent contained in the toner and the method for confirming the release of the release agent by SEM are as follows.

<DSC measurement method>
Using a differential scanning calorimeter (DSC6200 (Seiko Instruments Inc.)), the sample (toner) was heated to 170 ° C., and the sample was once cooled to 30 ° C. at a cooling rate of 10 ° C./min. The sample is heated again to 170 ° C. at a heating rate of 10 ° C./min, and a DSC curve is obtained by measurement during reheating. The sample amount is 10 mg. A typical example of the DSC curve of the toner is shown in FIG. From the obtained DSC curve, endothermic start temperature (TB) and endothermic end temperature (TE) are determined. Specifically, the intersection of the baseline of the DSC curve after the toner glass transition point (Tg, point A) is observed and the tangent at the inflection point on the lowest temperature side of the descending curve in the first endothermic peak. Let temperature be TB. Also, let TE be the temperature at the intersection of the baseline of the DSC curve after the second endothermic peak and the tangent at the inflection point on the highest temperature side of the rising curve at the second endothermic peak. A point on the DSC curve corresponding to the temperature TB is defined as a point B, and a point corresponding to the temperature TE is defined as a point E. The toner endothermic amount (J / g) is obtained from the area of the portion surrounded by the DSC curve and the straight line connecting the points B and E on the DSC curve.

<SEM observation method>
With respect to 100 or more, preferably 100 to 150 toner particles included in an image photographed with a scanning electron microscope at a magnification of 3000 times, an image photographed at a magnification of 10,000 times is visually released from the toner surface. Check for bleeding of agent. When the release agent oozes out on the toner surface, a protruding release agent block is observed on the toner surface. In the electron microscope image, the external additive on the toner surface and the release agent that has oozed out on the toner surface can be easily identified by the shape. When the number% of the toner particles exuding the release agent on the surface of the toner with respect to the number of toner particles to be observed is 10% or less, the exfoliation of the release agent is regarded as not exceeding 10% by number. Is exuded with release agent.

(Charge control agent)
The electrostatic latent image developing toner may contain a charge control agent in the binder resin. The purpose of the charge control agent is to improve the charge level of the toner and to improve the charge rise characteristic that is an indicator of whether or not the toner can be charged to a predetermined charge level in a short time, and to obtain a toner having excellent durability and stability. used. When developing with positively charged toner, a positively chargeable charge control agent is used. When developing with negatively charged toner, a negatively chargeable charge control agent is used.

  The type of the charge control agent is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from charge control agents conventionally used in toners. Specific examples of the positively chargeable charge control agent include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, azine Direct dyes composed of azine compounds such as Laun 3G, Azin Light Brown GR, Azin Dark Green BH / C, Azin Dep Black EW, and Azin Dee Black 3RL; Nigrosine Compounds such as Nigrosine, Nigrosine Salts, Nigrosine Derivatives; Nigrosine Acid dyes comprising nigrosine compounds such as BK, nigrosine NB, and nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride It is done. Among these positively chargeable charge control agents, a nigrosine compound is particularly preferable in that a quick charge rising property can be obtained. These positively chargeable charge control agents can be used in combination of two or more.

  Quaternary ammonium salts, carboxylates, or resins having a carboxyl group as a functional group can also be used as a positively chargeable charge control agent. More specifically, a styrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, a carboxylic acid Styrene resin with salt, acrylic resin with carboxylate, styrene-acrylic resin with carboxylate, polyester resin with carboxylate, polystyrene resin with carboxyl group, acrylic with carboxyl group 1 type, or 2 or more types, such as resin, the styrene-acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. The molecular weight of these resins is not particularly limited as long as the object of the present invention is not impaired, and may be an oligomer or a polymer.

  Among resins that can be used as a positively chargeable charge control agent, a styrene-acrylic copolymer having a quaternary ammonium salt as a functional group from the viewpoint that the charge amount can be easily adjusted to a value within a desired range. A resin is more preferable. Specific examples of preferable acrylic comonomers to be copolymerized with styrene units in a styrene-acrylic copolymer resin having a quaternary ammonium salt as a functional group include methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic acid. (Meth) such as iso-propyl, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate Examples include alkyl acrylates.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate, dialkyl (meth) acrylamide, or dialkylaminoalkyl (meth) acrylamide through a quaternization step is used. Specific examples of the dialkylaminoalkyl (meth) acrylate include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like. Specific examples of dialkyl (meth) acrylamide include dimethylmethacrylamide, and specific examples of dialkylaminoalkyl (meth) acrylamide include dimethylaminopropylmethacrylamide. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.

  Specific examples of the negatively chargeable charge control agent include organometallic complexes and chelate compounds. Examples of organometallic complexes and chelate compounds include acetylacetone metal complexes such as aluminum acetylacetonate and iron (II) acetylacetonate, and salicylic acid metal complexes or salicylic acid systems such as chromium 3,5-di-tert-butylsalicylate. Metal salts are preferable, and salicylic acid metal complexes or salicylic acid metal salts are more preferable. These negatively chargeable charge control agents can be used in combination of two or more.

  The amount of the positively or negatively chargeable charge control agent used is not particularly limited as long as the object of the present invention is not impaired. The amount of the positively or negatively chargeable charge control agent used is typically preferably 1.5 to 15 parts by mass, and 2.0 to 8.0 parts by mass when the total amount of toner is 100 parts by mass. Part is more preferable, and 3.0 to 7.0 parts by weight is particularly preferable. When the amount of the charge control agent used is too small, it is difficult to stably charge the toner to a predetermined polarity, which may make it difficult to reduce the image density of the formed image or to maintain the image density over a long period of time. . In such a case, the charge control agent is difficult to uniformly disperse, so that the formed image is likely to be fogged or the latent image carrier is easily contaminated. When the amount of the charge control agent used is excessive, image defects in the formed image due to poor charging under high temperature and high humidity due to deterioration in environmental resistance, contamination of the latent image carrier, and the like are likely to occur.

[Magnetic powder]
In the toner according to the first embodiment, magnetic powder can be blended in the binder resin as desired. The type of magnetic powder to be blended with the toner is not particularly limited as long as the object of the present invention is not impaired. Examples of suitable magnetic powders include: irons such as ferrite and magnetite; ferromagnetic metals such as cobalt and nickel; alloys containing iron and / or ferromagnetic metals; compounds containing iron and / or ferromagnetic metals; A ferromagnetic alloy subjected to a ferromagnetization treatment such as chromium dioxide.

  The particle size of the magnetic powder is not limited as long as the object of the present invention is not impaired. The particle diameter of the specific magnetic powder is preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0.5 μm. When magnetic powder having a particle diameter in such a range is used, it is easy to uniformly disperse the magnetic powder in the binder resin.

  The magnetic powder can be used that has been surface-treated with a surface treatment agent such as a titanium coupling agent or a silane coupling agent for the purpose of improving dispersibility in the binder resin.

  The usage-amount of magnetic powder is not specifically limited in the range which does not inhibit the objective of this invention. When the toner is used as a one-component developer, the specific amount of the magnetic powder is preferably 35 to 60 parts by mass, more preferably 40 to 60 parts by mass when the total amount of toner is 100 parts by mass. If the amount of magnetic powder used is excessive, the image density may be easily lowered or the fixability may be extremely lowered when printing over a long period of time. If the amount of magnetic powder used is too small, fogging is likely to occur, and the image density may be likely to decrease when printing over a long period of time. When toner is used as a two-component developer, the amount of magnetic powder used is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less when the total amount of toner is 100 parts by mass.

[Carrier]
The electrostatic latent image developing toner according to the first embodiment can be mixed with a desired carrier and used as a two-component developer. When preparing a two-component developer, it is preferable to use a magnetic carrier.

  Suitable carriers when the electrostatic latent image developing toner of the present invention is used as a two-component developer include those in which a carrier core material is coated with a resin. Specific examples of carrier core materials include particles of iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, cobalt, etc., and particles of alloys of these materials with manganese, zinc, aluminum, etc. , Particles such as iron-nickel alloy, iron-cobalt alloy, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate , Ceramic particles such as lead zirconate and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and Rochelle salt, resin carriers in which the above magnetic particles are dispersed in a resin, etc. Is mentioned.

  Specific examples of the resin covering the carrier core material include (meth) acrylic polymers, styrene polymers, styrene- (meth) acrylic copolymers, olefin polymers (polyethylene, chlorinated polyethylene, polypropylene, etc. ), Polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluororesin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoride) Vinylidene chloride, etc.), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, amino resin and the like. These resins can be used in combination of two or more.

  The particle diameter of the carrier is not particularly limited as long as the object of the present invention is not impaired, but is preferably 20 to 120 μm, more preferably 25 to 80 μm, as measured by an electron microscope.

The apparent density of the carrier is not particularly limited as long as the object of the present invention is not impaired. The apparent density varies depending on the carrier composition and surface structure, but is typically 2.0 to 2.5 g / cm ³ .

  When the toner for developing an electrostatic latent image is used as a two-component developer, the toner content is preferably 1 to 20% by mass and more preferably 3 to 15% by mass with respect to the mass of the two-component developer. By setting the toner content in the two-component developer within such a range, an appropriate image density in the formed image is maintained, and toner contamination is suppressed and toner adhesion to the transfer paper or the like is suppressed by suppressing toner scattering. it can.

[Method for producing toner for developing electrostatic latent image]
In the method for producing a toner for developing an electrostatic latent image according to the first embodiment, at least a colorant and a release agent are blended in a polyester resin as a binder resin, and the average circularity of the toner, the toner The endothermic amount at the time of melting of the release agent as measured by a differential scanning calorimeter can be set to a predetermined value and is not particularly limited as long as the release of the release agent to the toner surface can be suppressed.

As a suitable method for producing the electrostatic latent image developing toner according to the first embodiment, a method including the following steps (I) to (IV) may be mentioned. Hereinafter, the steps (I) to (IV) will be described in order.
(I) a step of melt-kneading the binder resin and at least the colorant and the release agent after mixing;
(II) A step of roughly pulverizing the melt-kneaded product obtained in step (I) to obtain a coarsely pulverized product having a volume average particle diameter of 15 to 25 μm;
(III) a step of heat-treating the coarsely pulverized product; and (IV) a step of obtaining a toner having a volume average particle diameter of 5 to 10 μm by finely pulverizing the coarsely pulverized product that has been heat-treated.

  In step (I), a colorant and a release agent, which are essential components, are mixed with a binder resin, if necessary, a charge control agent, magnetic powder, and the like, and then the obtained mixture is melt-kneaded. And obtaining a melt-kneaded product. The method of mixing the binder resin and the components such as the colorant and the release agent is not particularly limited as long as these materials can be mixed uniformly. A specific example of a preferable mixing method includes a method using a mixer such as a Henschel mixer. The method of melt kneading the obtained mixture is not particularly limited as long as the mixture can be sufficiently kneaded with the binder resin melted. A preferred method for melt-kneading the mixture is a method using a kneading apparatus such as a single-screw or twin-screw extruder. The melt-kneaded product obtained in the step (I) is cooled and then subjected to the step (II).

  Step (II) is a step of roughly pulverizing the melt-kneaded product obtained in Step (I) to obtain a coarsely pulverized product having a volume average particle size of 15 to 25 μm. The method of coarsely pulverizing the melt-kneaded product can be appropriately selected from methods conventionally employed in the coarse pulverization step in the toner production method using the pulverization method. As a suitable coarse pulverization method, for example, a method using a mechanical pulverizer such as a rotoplex pulverizer may be mentioned. The volume average particle diameter of the coarsely pulverized product can be adjusted by adjusting the operating conditions of the mechanical pulverizer such as the rotational speed and the processing time of the coarse pulverization. Further, after the coarse pulverization, classification treatment may be performed for the purpose of adjusting the volume average particle size and particle size distribution of the coarsely pulverized product. The volume average particle diameter of the coarsely pulverized product can be measured using, for example, Coulter Counter Multisizer 3 (manufactured by Beckman Coulter, Inc.).

  When the volume average particle diameter of the coarsely pulverized product obtained in the step (II) is excessive, the particles of the coarsely pulverized product are large even if the coarsely pulverized product is heat-treated and spheroidized in the subsequent step (III). In the fine pulverization in (IV), the pulverization is likely to proceed in the same process as the coarsely pulverized product that has not been heat-treated, and the average circularity of the obtained toner tends to be small. When the volume average particle diameter of the coarsely pulverized product is too small, the particles of the coarsely pulverized product heat-treated in the step (III) are small, so that the finely pulverized powder in the step (IV) is crushed in a rounded state. And the average circularity of the obtained toner tends to increase.

  Step (III) is a step in which the coarsely pulverized product obtained in Step (II) is heat treated to spheroidize the coarsely pulverized product. When the coarsely pulverized product is finely pulverized as it is, the irregularly pulverized coarsely pulverized product is pulverized, so that the finely pulverized powder tends to be particles with low circularity. On the other hand, when the coarsely pulverized product is spheroidized, the surface of the particles of the coarsely pulverized product is nearly spherical, so that the finely pulverized particles are easily rounded, and the finely pulverized particles easily obtain particles having a high degree of circularity. When the coarsely pulverized product spheroidized by heat treatment is finely pulverized, the coarsely pulverized product is pulverized while maintaining roundness. In this case, friction between particles during pulverization is reduced, and exfoliation of the release agent to the toner surface due to drop-off of the release agent from the particle surface and softening / melting of the release agent is suppressed.

  The heat treatment conditions in step (III) are not particularly limited as long as the object of the present invention is not impaired. Typically, the heat treatment condition is preferably 200 to 400 ° C, more preferably 250 to 350 ° C with respect to the temperature. The heat treatment is usually performed instantaneously in order to avoid melting of the coarsely pulverized product and fusion between the coarsely pulverized products. The heat treatment method for the coarsely pulverized product is not particularly limited as long as the coarsely pulverized product can be spheroidized. As a preferable heat treatment method, a method using a heat treatment apparatus such as saffusion (manufactured by Nippon Pneumatic Industry Co., Ltd.) can be mentioned.

  Step (IV) is a step of obtaining a toner having a volume average particle diameter of 5 to 10 μm by finely pulverizing the heat-treated coarsely pulverized product obtained in step (III). The method for finely pulverizing the heat-treated coarsely pulverized product can be appropriately selected from methods conventionally employed in the fine pulverization step in the toner production method using the pulverization method. A specific example of a suitable pulverization method is a method using a mechanical pulverizer such as a turbo mill (manufactured by Turbo Industry Co., Ltd.). The method for classifying the finely pulverized powder is not particularly limited as long as the volume average particle diameter of the toner can be adjusted to a desired diameter. A specific example of a suitable classification method is a method using an air classifier such as Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.). The volume average diameter of the toner can be measured in the same manner as the volume average diameter of the coarsely pulverized product.

  The average circularity of the toner according to the first embodiment is 0.960 to 0.975. In step (III), the coarsely pulverized product is heat-treated to obtain a toner having an average circularity by fine pulverization. Further, the average circularity of the toner can be adjusted by the fine pulverization conditions in the step (IV). Specifically, when fine pulverization is performed by one pulverization operation, the average circularity of the toner is lowered, and when fine pulverization is performed in two or more times, the toner is increased by increasing the number of pulverizations. The average circularity can be increased.

  When pulverizing to a desired particle size at a time by a mechanical pulverizer, the particle size changes mainly due to the corners and surroundings of the toner particles being scraped at the initial stage of the pulverization step, Since the corners of the toner particles are removed, the particle diameter mainly changes due to the cracking of the toner particles, and it seems that toner particles having a lower average circularity can be obtained. On the other hand, when the pulverization is performed in a plurality of times by a mechanical pulverizer, it is possible to increase the ratio of the particle diameter change due to the sharpening of the particle corners while suppressing the decrease in the average circularity due to the toner particle cracking. It is considered that toner particles having a relatively large average circularity can be obtained.

The average circularity of the toner can be measured according to the following method.
<Average circularity measurement method>
The circularity of the toner is measured using a flow type particle image analyzer (FPIA-3000 (manufactured by Sysmex Corporation)). In an environment of 23 ° C. and 60% RH, the circumference of a circle having the same projected area as the particle image (L ₀ ) and the particle projection image The outer circumference length (L) is measured, and the circularity is determined by the following equation. A value obtained by dividing the sum of the circularity of particles having an equivalent circle diameter of 3 to 10 μm by the total number of particles having an equivalent circle diameter of 3 to 10 μm is defined as an average circularity.
(Circularity calculation formula) Circularity = L ₀ / L

  When the average circularity of the toner is excessive, the toner approaches a true sphere, so that when the toner comes into contact with the surface of the cleaning unit or the latent image carrying unit, the toner easily rolls and the toner cleaning unit easily slips through. When the average circularity of the toner is excessively small, the toner may adhere firmly to the surface of the latent image carrying part on the surface along the major axis direction, and an image defect in the void is likely to occur.

  The toner of the first embodiment may be one in which an external additive is attached to the surface for the purpose of improving the fluidity, storage stability, cleaning properties, etc. of the toner. In the case of producing a toner containing an external additive, a step of attaching the external additive to the toner surface is performed after the steps (I) to (IV).

  The type of external additive is not particularly limited as long as it does not impair the object of the present invention, and can be appropriately selected from external additives conventionally used for toners. Specific examples of suitable external additives include silica and metal oxides such as alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate. These external additives can be used in combination of two or more.

  The particle diameter of the external additive is not particularly limited as long as the object of the present invention is not impaired, and typically 0.01 to 1.0 μm is preferable.

  The volume specific resistance value of the external additive can be adjusted by forming a coating layer made of tin oxide and antimony oxide on the surface of the external additive and changing the thickness of the coating layer and the ratio of tin oxide to antimony oxide. .

  The amount of the external additive used relative to the toner base particles is not particularly limited as long as the object of the present invention is not impaired. The amount of the external additive used is typically preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the toner base particles before being processed with the external additive. preferable. When the external additive is used in such an amount, it is easy to obtain a toner excellent in fluidity, storage stability, and cleaning properties.

  The method of attaching the external additive to the surface of the toner particles is not particularly limited. For example, the mixing conditions are adjusted by a mixer such as a Henschel mixer or a Nauter mixer so that the external additive is not embedded in the toner particles. And a method of mixing toner particles and an external additive.

(Image forming method)
The image forming apparatus used when forming an image using the electrostatic latent image developing toner according to the first embodiment described above is not particularly limited as long as a good image can be formed. It is suitably selected from the forming apparatus. The image forming apparatus used when forming an image with the electrostatic latent image developing toner of the first embodiment is preferably a tandem color image forming apparatus using a plurality of colors of toner as described later. Here, an image forming method using a tandem color image forming apparatus will be described.

  Note that the tandem color image forming apparatus described below has a plurality of latent images arranged in parallel in a predetermined direction in order to form toner images of different colors of toner on the surface of each latent image carrier. An image carrier and a roller (development sleeve) that is disposed to face each latent image carrier and carries toner on the surface and transports the toner to the surface of each latent image carrier. A plurality of developing units, and the electrostatic latent image developing toner of the first embodiment is supplied to the latent image carrying unit in the developing unit.

  FIG. 2 is a schematic diagram showing a configuration of a preferred image forming apparatus. Here, the color printer 1 will be described as an example of the image forming apparatus.

  As shown in FIG. 2, the color printer 1 has a box-shaped device main body 1a. In the apparatus main body 1a, a toner image based on image data and the like is transferred to the paper P while feeding the paper P fed from the paper feeding unit 2 and the paper P fed from the paper feeding unit 2. An image forming unit 3 and a fixing unit 4 for performing a fixing process for fixing the unfixed toner image transferred onto the paper P by the image forming unit 3 to the paper P are provided. Further, on the upper surface of the apparatus main body 1a, a paper discharge unit 5 for discharging the paper P subjected to the fixing process by the fixing unit 4 is provided.

  The paper feed unit 2 includes a paper feed cassette 121, a pickup roller 122, paper feed rollers 123, 124, 125, and a registration roller pair 126. The paper feed cassette 121 is provided so as to be detachable from the apparatus main body 1a and stores the paper P. The pickup roller 122 is provided at the upper left position of the paper feed cassette 121 shown in FIG. 2 and takes out the paper P stored in the paper feed cassette 121 one by one. The paper feed rollers 123, 124, and 125 send out the paper P picked up by the pickup roller 122 to the paper transport path. The registration roller 126 temporarily waits for the paper P sent to the paper transport path by the paper feed rollers 123, 124, 125, and then supplies the paper P to the image forming unit 3 at a predetermined timing.

  The paper feeding unit 2 further includes a manual feed tray (not shown) and a pickup roller 127 that are attached to the left side surface of the device main body 1a shown in FIG. The pickup roller 127 takes out the paper P placed on the manual feed tray. The paper P taken out by the pickup roller 127 is sent out to the paper transport path by the paper feed rollers 123 and 125, and is supplied to the image forming unit 3 by the registration roller 126 at a predetermined timing.

  The image forming unit 3 includes an image forming unit 7, an intermediate transfer belt 31 on which a toner image based on image data transmitted from a computer or the like to the surface (contact surface) of the image forming unit 7 is primarily transferred, A secondary transfer roller 32 is provided for secondary transfer of the toner image on the intermediate transfer belt 31 onto the paper P fed from the paper feed cassette 121.

  The image forming unit 7 includes a black unit 7K, a yellow unit 7Y, and a cyan unit 7C that are sequentially arranged from the upstream side (right side in FIG. 2) to the downstream side in the moving direction of the intermediate transfer belt 31. And a magenta unit 7M. In each of the units 7K, 7Y, 7C, and 7M, a drum-type latent image carrier 37, which is an image carrier, is disposed at the center position so as to be rotatable in the arrow (clockwise) direction. Around each latent image carrier 37, a charging unit 39, an exposure unit 38, a developing unit 71, a cleaning unit 8, a static eliminator, and the like are sequentially arranged from the upstream side in the rotation direction of the latent image carrier 37. ing.

  The charging unit 39 uniformly charges the peripheral surface of the latent image carrying unit 37 rotated in the direction of the arrow. The charging unit 39 is not particularly limited as long as the peripheral surface of the latent image carrying unit 37 can be uniformly charged, and may be a non-contact type or a contact type. Specific examples of the charging unit include a corona charging device, a charging roller, and a charging brush.

  The surface potential (charging potential) of the latent image carrier 37 is not particularly limited as long as the object of the present invention is not impaired. Considering the balance between the developability and the charging ability of the latent image carrier 37, the surface potential is preferably +200 to + 500V, more preferably + 200V to + 300V. When the surface potential is too low, the developing electric field is insufficient and it is difficult to ensure the image density of the formed image. When the surface potential is too high, problems such as insufficient charging ability, dielectric breakdown of the latent image carrier 37, and increase in the amount of ozone generated are likely to occur depending on the film thickness of the photosensitive layer.

  As the latent image carrier 37, an inorganic photoreceptor such as amorphous silicon; an organic photoreceptor in which a single layer or a laminated photosensitive layer containing a charge generator, a charge transport agent, a binder resin, etc. is formed on a conductive substrate. Etc.

  The exposure unit 38 is a so-called laser scanning unit, and laser light based on image data input from a personal computer (PC), which is a host device, on the peripheral surface of the latent image carrier 37 uniformly charged by the charging unit 39. To form an electrostatic latent image based on the image data on the latent image carrier 37. The developing unit 71 supplies the toner of the first embodiment to the peripheral surface of the latent image carrying unit 37 on which the electrostatic latent image is formed, and forms a toner image based on the image data. By using the toner of the first embodiment, it is possible to suppress the toner from adhering to the developing roller (sleeve) provided in the developing unit 71, and a good image can be formed. The configuration of the developing unit 71 is appropriately changed depending on the type of developer and the developing method. The toner image formed on the peripheral surface of the latent image carrier 37 by the developing unit 71 is primarily transferred to the intermediate transfer belt 31.

  After the primary transfer of the toner image to the intermediate transfer belt 31 is completed, the toner remaining on the peripheral surface of the latent image carrier 37 is cleaned by the cleaning unit 8. The cleaning unit 8 includes an elastic blade 81, and removes toner remaining on the peripheral surface of the latent image holding unit 37 by the elastic blade 81. The elastic blade is made of urethane rubber or ethylene-propylene rubber. When the toner according to the first embodiment is used, it is difficult for the toner cleaning unit 8 to slip through, and the occurrence of image defects can be suppressed.

  The static eliminator neutralizes the peripheral surface of the latent image carrier 37 after the primary transfer is completed. The peripheral surface of the latent image carrier 37 cleaned by the cleaning unit 8 and the static eliminator goes to the charging unit 39 for a new charging process, and a new charging process is performed.

  The intermediate transfer belt 31 is an endless belt-like rotating body, and includes a driving roller 33, a driven roller 34, a backup roller 35, and a front surface (contact surface) side in contact with the peripheral surface of each latent image carrier 37. And a plurality of rollers such as the primary transfer roller 36. The intermediate transfer belt 31 is configured to rotate endlessly by a plurality of rollers in a state in which the intermediate transfer belt 31 is pressed against the latent image carrier 37 by a primary transfer roller 36 disposed to face each latent image carrier 37. . The driving roller 33 is rotationally driven by a driving source such as a stepping motor (not shown), and gives a driving force to the intermediate transfer belt 31 for endless rotation. The driven roller 34, the backup roller 35, and the primary transfer roller 36 are rotatably provided, and are driven to rotate with the endless rotation of the intermediate transfer belt 31 by the driving roller 33. These rollers 34, 35, 36 are driven to rotate via the intermediate transfer belt 31 according to the main rotation of the drive roller 33 and support the intermediate transfer belt 31.

  The primary transfer roller 36 applies a primary transfer bias to the intermediate transfer belt 31. By doing so, the toner image formed on each latent image carrying portion 37 is moved between each latent image carrying portion 37 and the primary transfer roller 36 by driving the drive roller 33 (counterclockwise). The images are sequentially transferred (primary transfer) in an overcoated state to the intermediate transfer belt 31 that circulates in the direction.

  The secondary transfer roller 32 applies a secondary transfer bias to the paper P. By doing so, the toner image primarily transferred onto the intermediate transfer belt 31 is secondarily transferred onto the paper P between the secondary transfer roller 32 and the backup roller 35, thereby transferring the color onto the paper P. An image (unfixed toner image) is transferred.

  The fixing unit 4 performs a fixing process on the transfer image transferred to the paper P by the image forming unit 3. The fixing unit 4 is disposed opposite to the heating roller 41 heated by the energized heating element and the heating roller 41. Is provided with a pressure roller 42 that is pressed against the peripheral surface of the heating roller 41.

  The transfer image transferred to the paper P by the secondary transfer roller 32 in the image forming unit 3 is fixed by heating and pressurization when the paper P passes between the heating roller 41 and the pressure roller 42. It is fixed on the paper P by the processing. The paper P subjected to the fixing process is discharged to the paper discharge unit 5. Further, in the color printer 1 of the present embodiment, a plurality of conveyance roller pairs 6 are disposed at appropriate positions between the fixing unit 4 and the paper discharge unit 5.

  The paper discharge unit 5 is formed by recessing the top of the device main body 1a of the color printer 1, and a paper discharge tray 51 for receiving the discharged paper P is formed at the bottom of the concave portion. .

  The color printer 1 forms an image on the paper P by the image forming operation as described above. By forming the image using the toner of the first embodiment, the fixing roller and the recording medium on which the image is formed are well separated, and the toner adheres to the developing sleeve in the formed image. It is possible to suppress image defects such as image defects, image defects due to toner passing through the cleaning unit, and voids.

[Second Embodiment]
The second embodiment is a toner set comprising the electrostatic latent image developing toner of the first embodiment, wherein the colorant is a colorant of black and the other three hues of black, each having a different hue. A toner set including the four types of electrostatic latent image developing toners. In the toner according to the second embodiment, the difference between the maximum value and the minimum value of the endothermic amount at the time of melting of the release agent measured by the differential scanning calorimeter among the four types of toner included in the toner set is 0. .5 J / g or less.

  The hue of each toner included in the toner set according to the second embodiment is not particularly limited as long as it includes a black toner and can form a color image with a favorable hue. Typically, the toner set according to the second embodiment is composed of four color toners of black, yellow, cyan, and magenta.

  In the case of the toner according to the first embodiment, the binder resin is easily filled with a predetermined amount of the release agent. Further, when the toner set is composed of four colors of toner including the colorant of black and the other three hues, which is the toner of the first embodiment, the mold release in the binder resin in each color toner Variation in the content of the agent is reduced. For this reason, in the toner set according to the second embodiment, the difference between the maximum value and the minimum value of the endothermic amount at the time of melting of the release agent measured by the differential scanning calorimeter in the four types of toner included in the toner set. Becomes 0.5 J / g or less.

  Therefore, according to the toner set of the second embodiment, when an image formed with four color toners is fixed at the same temperature, there is a variation in gloss of the images after fixing between the toners of the respective colors. The image quality of the formed image is less likely to be reduced due to uneven gloss.

[Third Embodiment]
The third embodiment is a method for producing a toner for developing an electrostatic latent image, which contains at least a colorant and a release agent in a binder resin, wherein the binder resin is a polyester resin, and the following (I The present invention relates to a method for producing a toner for developing an electrostatic latent image including the steps (IV) to (IV). Steps (I) to (IV) in the toner manufacturing method according to the third embodiment are the same as steps (I) to (IV) in the toner manufacturing method of the first embodiment.

  According to the method for producing a toner for developing an electrostatic latent image according to the third embodiment, the binder resin can be highly filled while suppressing the seepage of the release agent to the toner surface. In addition, according to the method for producing a toner for developing an electrostatic latent image according to the third embodiment, a suitable average that hardly causes an image defect such as a void and hardly causes a problem of toner slippage at a cleaning unit. A toner having a circularity can be obtained. Note that a preferable range of the average circularity is typically 0.960 to 0.975.

  Therefore, according to the method for producing a toner for developing an electrostatic latent image according to the third embodiment, the releasability between the fixing roller and the recording medium on which the image has been formed is excellent, and the formed image can be applied to the developing sleeve. A toner for developing an electrostatic latent image with a small particle diameter using a polyester resin as a binder resin, which can suppress image defects due to toner adhesion, image defects due to toner passing through the cleaning section, and image defects such as voids. Can be manufactured.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.

[Preparation Example 1]
(Manufacture of polyester resin)
A polyester resin used as a binder resin in Examples and Comparative Examples was produced according to the following method.
1960 g of propylene oxide adduct of bisphenol A, 780 g of ethylene oxide adduct of bisphenol A, 257 g of dodecenyl succinic anhydride, 770 g of terephthalic acid, and 4 g of dibutyltin oxide were charged in a reaction vessel and stirred at 235 ° C. in a nitrogen atmosphere. The temperature rose. Subsequently, after reacting at the same temperature for 8 hours, the inside of reaction container was pressure-reduced to 8.3 kPa and reacted for 1 hour. Thereafter, the reaction mixture was cooled to 180 ° C., and trimellitic anhydride was added to the reaction vessel so as to obtain a desired acid value. Next, the reaction mixture was heated to 210 ° C. at a rate of 10 ° C./hour and reacted at the same temperature. After completion of the reaction, the contents in the reaction vessel were taken out and cooled to obtain a polyester resin.

[Example 1]
100 parts by mass of the polyester resin obtained in Preparation Example 1, 7 parts by mass of carnauba wax (carnauba wax 1 (manufactured by Kato Yoko Co., Ltd.)), 2 parts by mass of charge control agent (P-51 (manufactured by Orient Chemical Co., Ltd.)) And 5 parts by mass of carbon black (MA100 (manufactured by Mitsubishi Chemical Corporation)) were mixed with a mixer, and the mixture was melt-kneaded with a twin-screw extruder to obtain a kneaded product. The kneaded product was coarsely pulverized by a pulverizer (Rotoplex (manufactured by Toa Machinery Co., Ltd.)) to obtain a coarsely pulverized product having a volume average particle diameter (D50) of 20 μm. The obtained coarsely pulverized product was heat-treated at a treatment amount of 15 kg / h and 350 ° C. with a heat treatment apparatus (Saffusion (manufactured by Nippon Pneumatic Industry Co., Ltd.)), and the coarsely pulverized product was subjected to spheronization treatment. The coarsely pulverized product that has been spheroidized is gradually pulverized in three stages by a pulverizer (turbo mill (manufactured by Turbo Industry Co., Ltd.)), and then an airflow classifier (elbow jet (manufactured by Nippon Steel Mining Co., Ltd.)) Thus, toner mother particles having a volume average particle diameter (D50) of 6.8 μm were obtained.

  1. To 100 parts by mass of the obtained toner base particles, 1.8 parts by mass of hydrophobic silica (REA200 (made by Nippon Aerosil Co., Ltd.)) and titanium oxide (EC-100 (made by Titanium Industry Co., Ltd.)) 0 parts by mass was added, and the mixture was stirred and mixed for 5 minutes with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) at a rotational peripheral speed of 30 m / sec to obtain a black toner.

  Similar to black toner except that carbon black is changed to yellow pigment (CI Pigment Yellow 180), cyan pigment (CI Pigment Blue 15-3), or magenta pigment (CI Pigment Red 238). Thus, yellow toner, cyan toner, and magenta toner were obtained. The volume average particle diameter (D50) of the yellow toner base particles, cyan toner base particles, and magenta toner base particles was 6.8 μm.

  The average circularity of the black toner, yellow toner, cyan toner and magenta toner and the endothermic amount of the endothermic peak derived from the release agent were measured by the following methods. Table 1 shows the average circularity of black toner, yellow toner, cyan toner, and magenta toner, and the endothermic amount of the endothermic peak derived from the release agent. In addition, the average circularity of black toner, yellow toner, cyan toner, and magenta toner, and the difference between the maximum value and the minimum value of the endothermic peaks of the endothermic peaks derived from the release agent in the four color toners are shown. Write in 1. The average circularity and the endothermic amount were measured according to the following method.

<Average circularity measurement method>
The circularity of the toner was measured using a flow type particle image analyzer (FPIA-3000 (manufactured by Sysmex Corporation)). In an environment of 23 ° C. and 60% RH, the circumference of a circle having the same projected area as the particle image (L ₀ ) and the particle projection image The outer peripheral length (L) was measured, and the circularity was determined by the following equation. A value obtained by dividing the sum of the circularity of the particles having an equivalent circle diameter of 3 to 10 μm by the total number of the particles having an equivalent circle diameter of 3 to 10 μm was defined as an average circularity.
(Circularity calculation formula) Circularity = L ₀ / L

<DSC measurement method>
Using a differential scanning calorimeter (DSC6200 (Seiko Instruments Inc.)), the sample (toner) was heated to 170 ° C., and the sample was once cooled to 30 ° C. at a cooling rate of 10 ° C./min. The sample was heated again to 170 ° C. at a temperature rising rate of 10 ° C./min, and a DSC curve was obtained by measurement during reheating. The sample amount was 10 mg. From the obtained DSC curve, endothermic start temperature (TB) and endothermic end temperature (TE) were determined. Specifically, the intersection of the baseline of the DSC curve after the toner glass transition point (Tg, point A) is observed and the tangent at the inflection point on the lowest temperature side of the descending curve in the first endothermic peak. The temperature was TB. Further, the temperature at the intersection of the base line of the DSC curve after the second endothermic peak and the tangent at the inflection point on the highest temperature side of the rising curve at the second endothermic peak was defined as TE. A point on the DSC curve corresponding to the temperature TB is set as a point B, a point corresponding to the temperature TE is set as a point E, and a portion of the DSC curve surrounded by the line connecting the point B and the point E and the DSC curve The toner endothermic amount (J / g) was determined from the area.

  Further, for the four color toners prepared in Example 1, according to the following method, image quality (sleeve adhesion), transferability (missing), fixing separation property, cleaning property, exudation of release agent, gloss, and Gross unevenness was evaluated. The evaluation results of the toner of Example 1 are shown in Table 2.

<Image quality evaluation (sleeve adhesion evaluation)>
The carrier used in the developer for the printer (FS-C5016 (manufactured by Kyocera Mita Corporation)) and the toner of Example 1 are mixed at a ratio of 10 parts by weight of toner to 100 parts by weight of carrier 2 A component developer was obtained. A printer (FS-C5016 (manufactured by Kyocera Mita Corporation)) was used for evaluation of image quality. Two-component developer is filled in the developing device, and toner is filled in the toner container of the printer. Under an environment of 23 ° C. and 60% RH, the printing speed is 16 sheets / minute and the printing rate is 5%. Printing was continuously performed, and an image evaluation pattern was output after printing 5000 sheets. The solid image after printing 5000 sheets, the 50% half image, and the state of the developing sleeve were visually observed, and the image quality was evaluated according to the following criteria. The evaluation of sleeve adhesion was carried out for each of the four color toners using a single color, and the same evaluation result was obtained for each color toner. In addition, evaluation 5 was set as the pass.
5: No deposit was seen on the developing sleeve, and both the solid image and the 50% half image were good.
4: A small amount of deposits can be seen on the developing sleeve, but both solid images and 50% half images are good.
3: A large amount of deposits are seen on the developing sleeve, and image defects (sleeve layer unevenness) are slightly generated in the solid image and 50% half image at the pitch of the circumferential length of the developing sleeve.
2: A large amount of deposits are seen on the developing sleeve, and a large number of image defects (sleeve layer unevenness) occur in the solid image and the 50% half image at the circumferential length of the developing sleeve. Further, image defects due to the influence of the deposit on the developing sleeve start to occur during the durable printing of 5000 sheets.
1: A large amount of deposits are seen on the developing sleeve, and a large number of image defects (sleeve layer unevenness) occur in the solid image and 50% half image at a pitch of the circumference of the developing sleeve. In addition, image defects due to the influence of deposits on the developing sleeve are confirmed from the time of initial image formation.

<Evaluation of transferability (evaluation of voids)>
Evaluation was performed using a printer (FS-C5016 (manufactured by Kyocera Mita Corporation)). The two-component developer used in the image quality evaluation was filled in the developing device to form a fine line image. The presence or absence of voids on the fine line image was observed with a loupe, and the transferability was evaluated according to the following criteria. The transferability evaluation was performed for each of the four color toners using a single color, and the same evaluation result was obtained for each color toner. In addition, evaluation 5 was set as the pass.
5: No void occurred.
4: Very slightly hollow out.
3: Small amount of void occurred.
2: Many voids occur locally.
1: Significant voids occur over a wide area.

<Evaluation of fixing separation (evaluation of amount of toner that can be separated)>
A fixing tester in which an external driving device and a fixing temperature control device were attached to a fixing device (fixing unit) of a printer (FS-C5016 (manufactured by Kyocera Mita Corporation)) for fixing evaluation was used. Using a printer (FS-C5016 (manufactured by Kyocera Mita Corporation)), a solid unfixed image with a tip margin of 3 mm was obtained, and the obtained unfixed image was measured at a fixing temperature of 180 ° C. while measuring the amount of toner on the paper. The fixing tester was passed at a linear speed of 97 mm / sec. The amount of applied toner was changed in increments of 0.1 mg / cm ² , and the amount of applied toner (mg / cm ² ) at which the paper did not wrap around the fixing roller was defined as the separable amount of applied toner. The fixing separation property was evaluated according to the following criteria. The fixing separation evaluation was performed for each of the four color toners using a single color, and the same evaluation result was obtained for each color toner. In addition, evaluation made ○ pass.
○: Toner loading 2.0 mg / cm ² or more.
Δ: Toner loading amount 1.5 mg / cm ² Abnormality Less than 2.0 mg / cm ²
X: Amount of applied toner is less than 1.5 mg / cm ² .

<Evaluation of cleaning properties>
Evaluation was performed using a printer (FS-C5016 (manufactured by Kyocera Mita Corporation)). Immediately after the solid image was formed, a blank paper image was formed, and the state of toner passing through was visually observed and evaluated. The cleaning property evaluation was performed for each of the four color toners using a single color, and the same evaluation result was obtained for each color toner. In addition, the evaluation 3 was set as the pass.
3: No black streak due to toner slippage is observed in the blank paper image.
2: Slight black streaks due to toner slippage are slightly observed in the blank paper image.
1: Black streaks due to a large amount of toner passing through a blank paper image are confirmed.

<Evaluation of exudation of release agent>
With respect to 100 or more, preferably 100 to 150 toner particles included in an image photographed with a scanning electron microscope at a magnification of 3000 times, an image photographed at a magnification of 10,000 times is visually released from the toner surface. The exudation of the agent was confirmed. When the release agent oozes out on the toner surface, a protruding release agent block is observed on the toner surface. In the electron microscope image, the external additive on the toner surface and the release agent that has oozed out on the toner surface can be easily identified by the shape. When the number% of the toner particles exuding the release agent on the surface of the toner with respect to the number of toner particles to be observed is 10% or less, the exfoliation of the release agent is regarded as not exceeding 10% by number. Was exuded from the release agent.

<Evaluation of gross and unevenness of gloss>
Evaluation was performed using a printer (FS-C5016 (manufactured by Kyocera Mita Corporation)). As a recording medium, A4 size paper (C2 paper, 70 g paper (Fuji Xerox Co., Ltd.)) was used, and the short side was the transport direction. Three solid images with a size of 3 cm × 3 cm are located on the line connecting the middle points of the short sides of the paper, the center of the solid image is located on the center of the paper, and the center of the solid image An interval between them was formed to be 10 cm, and this was used as an evaluation image. The toner amount for forming a solid image was 0.7 mg / cm ² . Three glosses were measured for each solid image, and the average value of the gloss of the solid images in the five evaluation images was used as the gloss value of each toner. The gloss was measured using a gloss meter (PG-1M (manufactured by Nippon Denshoku Industries Co., Ltd.)) at an incident angle of 60 degrees according to the 60-degree specular gloss measurement method described in JIS-Z8741.

Three solid images of a single color were arranged horizontally, and an image in which each color was arranged vertically was output, and the gloss unevenness was visually evaluated. The evaluation criteria for gross unevenness are as follows. Evaluation 5 was set to pass.
5: No gloss unevenness.
4: Gross unevenness exists in part.
3: A lot of gloss unevenness exists, the glossy part and the non-glossy part can be seen, and the image is slightly difficult to see.
2: A lot of gloss unevenness exists, the glossy part and the non-glossy part can be clearly distinguished, and the image is difficult to see.
1: There are many gloss irregularities, the glossy part and the non-glossy part can be clearly distinguished, and the image is very difficult to see.

[Example 2]
Black toner, yellow toner, cyan toner, and magenta toner were prepared in the same manner as in Example 1 except that the number of pulverizations of the spheroidized coarsely pulverized product was changed from three to one. The toner obtained in Example 2 had a volume average particle diameter of 6.8 μm. The difference between the maximum value and the minimum value among the average circularity of the toner of Example 2, the endothermic amount at the time of melting of the release agent in the toner, and the endothermic amount at the time of melting of the release agent of the four color toners is shown. Write in 1.

  In addition, the toner of Example 2 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Example 2 are shown in Table 2.

Example 3
Black toner, yellow toner, cyan toner, and magenta toner were prepared in the same manner as in Example 1 except that the amount of carnauba wax used was changed from 7 parts by mass to 5 parts by mass. The toner obtained in Example 3 had a volume average particle diameter of 6.8 μm. Table 3 shows the difference between the maximum value and the minimum value among the average circularity of the toner of Example 3, the endothermic amount when the release agent melts in the toner, and the endothermic amount when the release agent of the four color toners melts. Write in 1.

  The toner of Example 3 was evaluated in the same manner as in Example 1 for image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Example 3 are shown in Table 2.

Example 4
Black toner, yellow toner, cyan toner and magenta toner were prepared in the same manner as in Example 1 except that the amount of carnauba wax used was changed from 7 parts by mass to 9 parts by mass. The volume average particle diameter of the toner obtained in Example 4 was 6.8 μm. Table 4 shows the difference between the maximum value and the minimum value among the average circularity of the toner of Example 4, the endothermic amount when the release agent melts in the toner, and the endothermic amount when the release agent of the four color toners melts. Write in 1.

  In addition, the toner of Example 4 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (blank loss), fixing separation property, cleaning property, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Example 4 are shown in Table 2.

[Comparative Example 1]
Black toner, yellow toner, cyan toner, and magenta toner were prepared in the same manner as in Example 1 except that the coarsely pulverized product was not heat-treated. The toner obtained in Comparative Example 1 had a volume average particle diameter of 6.8 μm. The difference between the maximum value and the minimum value among the average circularity of the toner of Comparative Example 1, the endothermic amount when the release agent in the toner melts, and the endothermic amount when the release agent of the four color toners melt is shown. Write in 1.

  The toner of Comparative Example 1 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Comparative Example 1 are shown in Table 2.

[Comparative Example 2]
Black toner, yellow toner, cyan toner, and magenta toner were prepared in the same manner as in Example 2 except that the coarsely pulverized product was not heat-treated. The toner obtained in Comparative Example 2 had a volume average particle diameter of 6.8 μm. The difference between the maximum value and the minimum value among the average circularity of the toner of Comparative Example 2, the endothermic amount when the release agent melts in the toner, and the endothermic amount when the release agent of the four color toners melt is shown. Write in 1.

  The toner of Comparative Example 2 was evaluated in the same manner as in Example 1 for image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Comparative Example 2 are shown in Table 2.

[Comparative Example 3]
Black toner, yellow toner, cyan toner, and magenta toner were prepared in the same manner as in Example 1 except that the amount of carnauba wax used was changed from 7 parts by weight to 4 parts by weight. The toner obtained in Comparative Example 3 had a volume average particle diameter of 6.8 μm. The difference between the maximum value and the minimum value among the average circularity of the toner of Comparative Example 3, the endothermic amount when the release agent in the toner melts, and the endothermic amount when the release agent of the four color toners melt is shown. Write in 1.

  The toner of Comparative Example 3 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (missing), fixing separation property, cleaning property, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Comparative Example 3 are shown in Table 2.

[Comparative Example 4]
Black toner, yellow toner, cyan toner, and magenta toner were prepared in the same manner as in Example 1 except that the amount of carnauba wax was changed from 7 parts by mass to 10 parts by mass. The toner obtained in Comparative Example 4 had a volume average particle diameter of 6.8 μm. A difference between the maximum value and the minimum value among the average circularity of the toner of Comparative Example 4, the endothermic amount when the release agent in the toner is melted, and the endothermic amount when the release agent of the four color toners is melted is shown. Write in 1.

  The toner of Comparative Example 4 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Comparative Example 4 are shown in Table 2.

[Comparative Example 5]
The heat treatment of the coarsely pulverized product was not performed, and the finely pulverized product was heat treated at a throughput of 15 kg / h at 350 ° C. with a heat treatment apparatus (Saffusion (manufactured by Nippon Pneumatic Industry Co., Ltd.)). In the same manner as in Example 1, black toner, yellow toner, cyan toner, and magenta toner were prepared. The toner obtained in Comparative Example 5 had a volume average particle diameter of 6.8 μm. The difference between the maximum value and the minimum value among the average circularity of the toner of Comparative Example 5, the endothermic amount when the release agent of the toner is melted, and the endothermic amount when the release agent of the four color toners is melted is shown. Write in 1.

  The toner of Comparative Example 5 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Comparative Example 5 are shown in Table 2.

[Comparative Example 6]
Carnauba wax is used in the same manner as in Example 1 except that black toner, yellow toner, cyan toner, and magenta toner are 5 parts by mass, 6 parts by mass, 7 parts by mass, and 8 parts by mass, respectively. Thus, a black toner, a yellow toner, a cyan toner, and a magenta toner were prepared. The toner obtained in Comparative Example 6 had a volume average particle diameter of 6.8 μm. A difference between the maximum value and the minimum value among the average circularity of the toner of Comparative Example 6, the endothermic amount when the release agent of the toner is melted, and the endothermic amount when the release agent of the four color toners is melted is shown. Write in 1.

  The toner of Comparative Example 6 was evaluated in the same manner as in Example 1 in terms of image quality (sleeve adhesion), transferability (missing), fixing separation, cleaning properties, gloss, and gloss unevenness. The evaluation results of the respective color toners were the same with respect to the evaluation results of the image quality (sleeve adhesion), transferability (blank), fixing separation property, and cleaning property. The evaluation results of the toner of Comparative Example 4 are shown in Table 2.

  Each of the toners of Examples 1 to 4 has an endothermic amount of 10.0 to 15.0 J / g at the time of melting of the release agent in the toner, and a stain of the release agent on the toner surface by SEM observation. No protrusion is observed. For this reason, the toners of Examples 1 to 4 can suppress image defects due to adhesion of the toner to the developing sleeve, and have good fixing separation properties.

  In addition, since the toners of Examples 1 to 4 have an average circularity in the range of 0.960 to 0.975, they are easily peeled off from the surface of the latent image carrying part, and the problem of slipping through the cleaning part hardly occurs. For this reason, the toners of Examples 1 to 4 have good transferability and cleanability.

  Further, in the toners of Examples 1 to 4, even when a multicolor toner is prepared, the content of the release agent in the binder resin is difficult to vary. For this reason, when black toner, yellow toner, cyan toner, and magenta toner obtained in Examples 1 to 4 are used as a toner set, uneven gloss is hardly generated in the formed image.

  The toners of Comparative Examples 1 and 2 are toners prepared in the same manner as in Example 1 and Example 2 except that the heat treatment of the coarsely pulverized product is not performed. Therefore, the toners of Comparative Examples 1 and 2 have an average circularity of less than 0.960, and a slight release of the release agent is observed. For this reason, the toners of Comparative Examples 1 and 2 are slightly inferior in transferability, and image defects due to adhesion of the toner to the developing sleeve are slightly likely to occur. Further, since the toners of Comparative Examples 1 and 2 tend to cause the release agent to exude to the toner surface, the endothermic amount when the release agent melts in the black toner, the yellow toner, the cyan toner, and the magenta toner. The difference between the maximum value and the minimum value exceeds 0.5 J / g. For this reason, when the black toner, yellow toner, cyan toner, and magenta toner obtained in Comparative Examples 1 and 2 are used, slight gloss unevenness occurs.

Since the toner of Comparative Example 3 was prepared using 4 parts by mass and a smaller amount of carnauba wax than in the Examples, the endothermic amount at the time of melting of the release agent in the toner is less than 10.0 J / g. Therefore,
The toner of Comparative Example 3 was inferior in fixing separation property.

  Since the toner of Comparative Example 4 was prepared using 10 parts by mass and a large amount of carnauba wax, the endothermic amount at the time of melting of the release agent in the toner exceeded 15.0 J / g. Therefore, although the toner of Comparative Example 4 is manufactured in the same process as in Example 1, the release agent oozes out easily on the toner surface. For this reason, the toner of Comparative Example 4 is liable to cause image defects due to toner adhesion to the developing sleeve.

  The toner of Comparative Example 5 is produced by heat-treating the finely pulverized product without heat-treating the coarsely pulverized product. For this reason, the toner of Comparative Example 5 has an average circularity exceeding 0.975, and since the average circularity is too high, it easily slips through the cleaning blade, resulting in poor cleaning performance. Further, in the toner of Comparative Example 5, since the finely pulverized product having a large specific surface area is heat-treated, the release agent oozes out on the toner surface. For this reason, the toner of Comparative Example 5 is slightly susceptible to image defects due to toner adhesion to the developing sleeve.

  In Comparative Example 6, a black toner, a yellow toner, a cyan toner, and a magenta toner, each having a different release agent content, are prepared. For this reason, it can be seen that when the four-color toner obtained in Comparative Example 6 is used as a toner set, significant gloss unevenness occurs.

DESCRIPTION OF SYMBOLS 1 Color printer 1a Apparatus main body 2 Paper feed part 3 Image formation part 37 Latent image holding part 38 Exposure part 39 Charging part 4 Fixing part 6 Conveyance roller 5 Paper discharge part 7 Image formation unit 71 Development part 8 Cleaning part 81 Elastic blade P Paper

Claims (3)

A toner for developing an electrostatic latent image containing at least a colorant and a release agent in a binder resin,
The binder resin is a polyester resin;
The electrostatic latent image developing toner has an average circularity of 0.960 to 0.975,
In the electrostatic latent image developing toner, the endothermic amount at the time of melting of the release agent measured by a differential scanning calorimeter is 10.0 to 15.0 J / g,
100 or more electrostatic latent image developing toner particles contained in an image taken at a magnification of 3000 times with a scanning electron microscope are confirmed by observing the image taken at a magnification of 10,000 times. mold agent number of particles of the electrostatic latent image developing toner exuding to the surface, the ratio with respect to the electrostatic latent image and the number of particles toner for developing observation target state, and are 10% by number or less, the following steps Toner for electrostatic latent image development produced by a method comprising (I) to (IV) :
(I) a step of melt-kneading the binder resin and at least the colorant and the release agent after mixing;
(II) A step of roughly pulverizing the melt-kneaded product obtained in step (I) to obtain a coarsely pulverized product having a volume average particle diameter of 15 to 25 μm;
(III) heat-treating the coarsely pulverized product; and
(IV) A step of finely pulverizing the coarsely pulverized product that has been heat-treated and classifying it to obtain the toner for developing an electrostatic latent image having a volume average particle diameter of 5 to 10 μm. The coloring agent is black, and a three other colors of black colorant, a toner set including four claim 1 Symbol mounting of the toner for developing an electrostatic latent image is different hues,
The difference between the maximum value and the minimum value of the endothermic amount at the time of melting of the release agent measured by a differential scanning calorimeter in the four types of toner for developing an electrostatic latent image included in the toner set is 0.5 J. / G or less, a toner set. A claim 1 electrostatic latent image producing method of the developing toner according, the following step (I) ~ containing (IV), an electrostatic latent image developing toner production method:
(I) a step of melt-kneading the binder resin and at least the colorant and the release agent after mixing;
(II) A step of roughly pulverizing the melt-kneaded product obtained in step (I) to obtain a coarsely pulverized product having a volume average particle diameter of 15 to 25 μm;
(III) a step of heat-treating the coarsely pulverized product; and (IV) the coarsely pulverized product that has been heat-treated is finely pulverized and classified to obtain the electrostatic latent image developing toner having a volume average particle diameter of 5 to 10 μm. Obtaining step.

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