JP5498774B2 - Toner for electrostatic latent image development, developer, toner set, and developer set - Google Patents

Description

  The present invention relates to an electrostatic latent image developing toner, developer, toner set for developing an electrostatic latent image formed in an image forming method such as electrophotography, electrostatic recording method, electrostatic printing method, and the like. The present invention relates to a developer set.

  As a small-sized image forming apparatus that forms a high-quality color image at a high speed, an image forming apparatus using a small tandem type hybrid development system is known (for example, see Patent Document 1). As an image forming apparatus using this developing method, for example, a plurality of two-component developers including a plurality of non-magnetic toners and a magnetic carrier are used as the developer, and a plurality of non-magnetic toners corresponding to the respective colors are used. Are arranged side by side. In each image forming unit, the two-component developer is held on the magnetic roller installed in the developing device, and only the non-magnetic toner is transferred from the developer held on the magnetic roller to the developing roller once installed in the developing device. Then, a toner thin layer is formed on the surface of the developing roller, and the toner image is developed on the photosensitive member by causing the toner to fly to the photosensitive member which is an image bearing member facing the developing roller through a gap.

  This development method is a non-contact development method in which there is a gap between the photosensitive member and the developing roller (developing sleeve). Body brazing is suppressed. Therefore, it is possible to improve the quality of the output image.

  An image forming apparatus using this developing system employs a two-component developer as a developer, and the toner is charged by mixing the developer in the developing device. For this reason, even in high density printing or continuous printing, the toner can be quickly charged to a desired charge amount.

JP 2004-280092 A JP 2001-109242 A

  However, in the image forming apparatus employing the small tandem hybrid developing system, there is a tendency that problems such as toner adhesion to the developing roller are likely to occur. This is because in the image forming apparatus adopting the small tandem type hybrid developing system, in order to minimize the size in the width direction, in each image forming unit, the vertical developing unit is positioned above the photosensitive member. Further, it is considered that the magnetic roller is disposed above the developing roller. For this reason, the developer is easily stressed, and it is considered that embedding of the external additive into the toner becomes remarkable when low density printing is repeated for a long period of time. Therefore, it is considered that the charge amount of the toner is increased, which causes problems such as toner adhesion to the developing roller.

  Here, the toner adhesion to the developing roller due to the increase in the toner charge amount will be described more specifically.

  In the small tandem type hybrid development system, the toner having a desired charge amount is supplied from the magnetic roller to the developing roller, and the toner remaining on the developing roller is collected without flying to the photosensitive member. Fresh toner is always supplied.

  However, since the magnetic roller is disposed above the developing roller, when collecting the residual toner on the developing roller, it is necessary to move the toner from the developing roller to the magnetic roller against gravity. Once the toner charge amount is increased, the image force on the developing roller is also increased, so that it is considered difficult to remove the developing roller from the magnetic roller. Then, it is considered that residual toner that has not been collected remains on the developing roller, and the increase in toner charge amount is further accelerated. In this way, it is considered that toner adheres to the developing roller and developability deteriorates.

  As a countermeasure for suppressing the adhesion of the toner to the developing roller, for example, it is conceivable to use a developing method in a developing device described in Patent Document 2.

  In Patent Document 2, a developing roller that carries a one-component toner and transports it to a developing area facing the electrostatic latent image carrier, and the developing roller is in contact with the developing roller before the toner is transported to the developing area. A supply roller for supplying toner, and after developing the electrostatic latent image on the latent electrostatic image bearing member in the developing region, at a predetermined time until the rotation of the developing roller is stopped to finish the developing operation; A developing device including a control unit that controls the voltage value so that the potential difference between the developing roller and the supply roller is opposite to the polarity of the potential difference that moves the toner toward the developing roller during development; Have been described. That is, it describes that the bias applied to the developing roller and the supply roller is controlled. More specifically, a bias voltage can be supplied between the developing roller and the supply roller so that an electric field in a direction in which the toner is attracted toward the developing roller acts, and a predetermined time before the development is completed. A method is disclosed in which switching control is performed so that an electric field in a direction in which the toner is attracted toward the supply roller acts.

  However, in a small tandem type hybrid development type image forming apparatus, even if the same method as described above is applied, there is a tendency that the toner remaining on the developing roller cannot be sufficiently peeled off by the magnetic roller. In Patent Document 2, a supply roller is provided so as to be pressed against the developing roller in order to directly scrape the residual toner, whereas in the small tandem type hybrid developing system, the magnetic roller is connected to the developing roller. This is considered to be due to being spaced apart. In Patent Document 2, no consideration is given to suppressing adhesion to the developing roller by improving the toner itself.

  In addition, with the recent increase in image quality, the toner particle size is proceeding toward a smaller particle size. By reducing the particle size of the toner to 10 μm or less, character scattering and fine line reproducibility are improved.

  However, in a small tandem type hybrid development type image forming apparatus, when, for example, pulverized toner is used as such a small particle size toner, the adhesion of the toner to the developing roller increases and the developability deteriorates. There was a trend. In this respect as well, Patent Document 1 and Patent Document 2 have not studied suppression of adhesion of a small particle size toner to the developing roller.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a toner for developing an electrostatic latent image that can suppress toner adhesion to a developing roller, that is, so-called sleeve adhesion. It is another object of the present invention to provide a developer containing the electrostatic latent image developing toner, a toner set containing the electrostatic latent image developing toner, and a developer set containing each toner of the toner set.

  In order to solve the above problems, the inventors of the present invention investigated the particle diameter of the toner on which the sleeve adheres in the image forming apparatus using the hybrid developing method, and most of them have a projected area circle equivalent diameter of 9 μm or less. there were. A phenomenon in which a portion where toner has not been transferred is formed in the formed image, that is, what induces so-called transfer omission is often a projected area equivalent circle diameter of 4 to 9 μm. Further, the shape of the toner on which the sleeve adheres is often an ellipse or a concave shape, and there are almost no spherical shapes. For these reasons, the toner having a projected area equivalent circle diameter of 4 to 9 μm out of all the toners can be made to have a uniform spherical shape, thereby preventing the occurrence of sleeve adhesion. It was found that can be reduced. Even when toners having various sizes of small and large particle sizes with a projected area circle equivalent diameter of 15 μm or less are used, the shape of the toner with a projected area circle equivalent diameter of 4 to 9 μm is made to have the same degree of circularity. By aligning, it has been found that even when the number (number of particles) of particles (toner and external additives) having a projected area equivalent circle diameter of less than 4 μm occupies up to about 60% of the total toner, occurrence of sleeve adhesion can be suppressed, The present invention has been completed.

An electrostatic latent image developing toner according to an aspect of the present invention is an electrostatic latent image developing toner including toner particles and an external additive externally added to the toner particles. When the average circularity of the toner having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm in the toner measured by the apparatus is Dn, the values from D4 to D8 are 0.94 or more, respectively. The difference (Dmax−Dmin) between the maximum value (Dmax) and the minimum value (Dmin) up to D8 is 0.015 or less, and the viscosity at 105 ° C. is 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s, The external additive contains linear saturated fatty acid metal salt particles having 14 or more carbon atoms.

  According to the above configuration, it is possible to suppress the adhesion of the sleeve, which is the adhesion of toner to the developing roller.

First, the value from D4 to D8 is 0.94 or more, and the difference (Dmax−Dmin) between the maximum value (Dmax) and the minimum value (Dmin) from D4 to D8 is 0.015 or less. Therefore, as compared with the conventional toner, each toner has a round shape close to a spherical shape, and the variation in circularity is small in the entire toner. Further, since the viscosity of the toner at 105 ° C. is 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s, it is considered that a toner having a nearly spherical shape is easily formed.

  This is considered to be due to the following. Specifically, for example, a toner having a roundness close to a sphere and having a small variation in circularity as described above is considered to have a small coefficient of contact friction with the photoreceptor. Furthermore, it is considered that when a linear saturated fatty acid metal salt particle having 14 or more carbon atoms is externally added to the toner particles as an external additive, the contact friction coefficient between the toner and the photosensitive member becomes smaller. As described above, it is considered that when the contact friction coefficient between the toner and the photoconductor is small, the toner constituting the toner image is easily peeled off from the photoconductor when the toner image is transferred.

  In addition, the electrostatic latent image developing toner is disposed so as to face a magnetic roller carrying and transporting a developer containing a non-magnetic toner and a magnetic carrier with a predetermined gap therebetween. A developing roller for carrying and transporting the non-magnetic toner in the developer on the surface; and an organic photoreceptor disposed opposite to the developing roller and forming an electrostatic latent image, and conveyed by the magnetic roller. The non-magnetic toner in the developer thus developed is transferred to the peripheral surface of the developing roller, and the non-magnetic toner conveyed by the developing roller is caused to fly to the surface of the organic photosensitive member. In an image forming apparatus that forms an image by developing an electrostatic latent image formed in advance as a toner image and transferring the toner image onto a recording medium, the image can be used as the non-magnetic toner. That. This makes it possible to transfer from an organic photoconductor that has a lot of unevenness and a large amount of friction even in an image forming apparatus of a hybrid development system that has an organic photoconductor with a lot of surface irregularities compared to an amorphous silicon photoconductor with a smooth surface. A decrease in efficiency can be prevented. Furthermore, even an organic photoconductor that is more easily scraped than an amorphous silicon photoconductor can be suitably formed into an image.

  The developer according to another aspect of the present invention is a developer including a non-magnetic toner and a magnetic carrier, and the non-magnetic toner is the electrostatic latent image developing toner. And According to such a configuration, it is possible to suppress the occurrence of sleeve adhesion in the image forming apparatus, and thus it is possible to form a high-quality image over a long period of time.

  In addition, a toner set according to another aspect of the present invention is an image forming method for forming an image by forming a toner image using a plurality of colors of toner and fixing the formed toner image on a recording medium. A plurality of color toners, wherein each of the plurality of color toners is the electrostatic latent image developing toner and has a value of all D4 to D8 in the plurality of color toners. The standard deviation is 0.004 or less.

  According to such a configuration, it is possible to suppress the adhesion of the sleeve, which is the adhesion of toner to the developing roller. In particular, even when a color image is formed in an image forming apparatus using a small tandem hybrid development system, the occurrence of sleeve adhesion is suppressed, and thus a high-quality color image is formed over a long period of time. be able to.

  The developer set according to another aspect of the present invention includes a plurality of colors of developer, and the plurality of colors of developer and the electrostatic latent image developing toner of each color constituting the toner set are magnetic. And a carrier.

  According to such a configuration, it is possible to suppress the adhesion of the sleeve, which is the adhesion of toner to the developing roller. In particular, even when a color image is formed in an image forming apparatus using a small tandem hybrid development system, the occurrence of sleeve adhesion is suppressed, and thus a high-quality color image is formed over a long period of time. be able to.

  According to the present invention, it is possible to provide a toner for developing an electrostatic latent image that can suppress the adhesion of the sleeve, which is the adhesion of the toner to the developing roller. In addition, a developer including the electrostatic latent image developing toner, a toner set including the electrostatic latent image developing toner, and a developer set including each toner of the toner set are provided.

1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus used in the present embodiment. FIG. 2 is a schematic cross-sectional view illustrating a configuration of an image forming unit provided in the image forming apparatus illustrated in FIG. 1. It is a conceptual diagram which shows the image for cleaning property evaluation. It is the schematic which shows the state of the photoreceptor drum at the time of evaluating cleaning property.

  Hereinafter, although the embodiment concerning the present invention is described, the present invention is not limited to these.

[toner]
An electrostatic latent image developing toner according to the present embodiment (hereinafter also referred to simply as “toner”) includes an electrostatic latent image including toner particles and an external additive externally added to the toner particles. D4 to D8 when the average circularity of a developing toner, which is measured by a flow type particle image analyzer and has a projected area circle equivalent diameter of n μm or more and less than n + 1 μm, is Dn. Each value is 0.94 or more, the difference (Dmax−Dmin) between the maximum value (Dmax) and the minimum value (Dmin) from D4 to D8 is 0.015 or less, and the viscosity at 105 ° C. is 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s, and the external additive contains linear saturated fatty acid metal salt particles having 14 or more carbon atoms.

  First, in the toner according to the present embodiment, when the average circularity of a toner having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm is Dn, the values from D4 to D8 are each 0.94 or more. That is, Dmin is 0.94 or more.

  When one or more of D4 to D8 is too small, when the toner image is transferred, the toner constituting the toner image is difficult to peel off from the photosensitive member, and there is a tendency that a transfer problem such as omission in transfer occurs. . In such a case, in the case of the whole toner, since the toner having a rounded shape close to a sphere is reduced, that is, the toner having a less rounded shape is increased, the contact friction coefficient between the toner and the photosensitive member is increased. This is thought to increase.

  Moreover, although Dmin should just be 0.94 or more, it is preferable that it is 0.945 or more, and it is so preferable that it is close to 1. By doing so, the toner having roundness close to a sphere as the whole toner increases, and the occurrence of transfer dropout is suppressed.

  Here, the average circularity Dn of particles having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm (for example, toner) is the circumference length of a circle having the same area as the two-dimensional projection image of particles of n μm or more and less than n + 1 μm. It is an average value of the circularity obtained by dividing by the perimeter of the two-dimensional projection image. The perimeter of the two-dimensional projection image can be measured using a flow particle image analyzer. Further, as the flow type particle image analyzer, for example, FPIA-2100 manufactured by Sysmex Corporation can be used.

  Specifically, the average circularity Dn of particles (for example, toner) having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm is a value measured as follows.

  First, the particle | grains (particle | grains which measure average circularity Dn) which are a measuring object are inserted into a flow type particle image analyzer (the Sysmex Corporation make, FPIA-3000). A two-dimensional projection image of particles having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm (where n is an integer of 0 or more) out of all the charged particles is obtained in an environment of 23 ° C. and 60% RH. Measured with That is, the measurement object was limited to particles having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm, and a two-dimensional projection image was measured in an environment of 23 ° C. and 60% RH. Then, the obtained two-dimensional projection image (two-dimensional projection image for each particle with a limited projected area circle equivalent diameter) is obtained with an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter (L) when image processing is performed is measured. Next, the circularity of each particle is calculated using the circumference (L0) of a circle having the same area as the two-dimensional projection image and the following formula (I).

a = L0 / L (I)
In the formula, a represents the circularity, L represents the perimeter when the two-dimensional projection image is image-processed, and L0 represents the perimeter of a circle having the same area as the two-dimensional projection image.

  Finally, a value obtained by dividing the sum of the circularity a of each particle limited to the projected area circle equivalent diameter by the number of particles having the projected area equivalent circle diameter of n μm or more and less than n + 1 μm is an average circularity of the particle size n μm. It is defined as Dn.

  The electrostatic latent image developing toner has a difference (Dmax−Dmin) between a maximum value (Dmax) and a minimum value (Dmin) from D4 to D8 of 0.015 or less and 0.010 or less. It is preferable. When the difference between the maximum value and the minimum value of Dn (Dmax−Dmin) is too large, when the toner image is transferred, the toner constituting the toner image is difficult to peel off from the photosensitive member, and transfer problems such as omission in transfer are caused. Tend to occur. This is considered to be due to variations in circularity distribution in the entire toner, and the coefficient of contact friction with the photosensitive drum varies among individual toners.

  And when two or more values from D4 to D8 are low and the difference (Dmax−Dmin) between the maximum value (Dmax) and the minimum value (Dmin) of Dn is too large, the distribution of circularity varies. The toner layer cannot be uniformly formed on the developing sleeve, and there is a tendency that a high-quality image cannot be formed. Specifically, image unevenness or the like tends to occur when outputting a solid image. This is considered to be due to the fact that the variation in the circularity distribution also affects the toner charge amount distribution, causing a phenomenon that the toner charge amount increases, and the toner causes charge aggregation on the developing sleeve.

The electrostatic latent image developing toner has a viscosity (melt viscosity) at 105 ° C. of 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s, and 6 × 10 ^{3 to} 5 × 10 ⁴ Pa · s. Preferably there is. When the melt viscosity of the toner is too low, there is a tendency for the image to become uneven due to the occurrence of transfer omission or sleeve adhesion due to charge aggregation on the developing sleeve. This is because when a toner is manufactured, a large amount of toner having a small particle size and distortion, that is, an elliptical toner is likely to be formed. As a result, a decrease in D4 and D5 is caused, and a variation in circularity distribution is large. It is thought that it becomes. In addition, when the melt viscosity of the toner is too low, in addition to the above problems, hot offset tends to occur, and there is a tendency that a high-quality image is not easily formed. On the other hand, if the melt viscosity is too high, the fixability tends to decrease and image defects tend to occur. Further, when the toner particles are produced by pulverizing a kneaded material made of toner particle raw materials, the pulverizability thereof is lowered, so that the toner productivity also tends to be lowered. Therefore, when the viscosity at 105 ° C. is within the above range, occurrence of sleeve adhesion can be suppressed and a high-quality image can be formed. Furthermore, when the viscosity at 105 ° C. is 6 × 10 ³ Pa · s or more, the variation in the circularity distribution is reduced, and the occurrence of sleeve adhesion is further suppressed. Further, when the viscosity at 105 ° C. is 5 × 10 ⁴ Pa · s or less, the pulverizability is superior and the productivity is further improved. In addition, it is possible to suppress the occurrence of fixing failure such as hot offset.

  Here, the viscosity at 105 ° C. is a value measured using a flow tester or the like. As the flow tester, CFT-500D manufactured by Shimadzu Corporation can be used.

  The viscosity at 105 ° C. is specifically a value measured as follows.

First, 2 g of electrostatic latent image developing toner, which is an object to be measured, is weighed and filled into a compression mold having an inner diameter corresponding to the inner diameter of a cylinder of a flow tester (CFT-500D manufactured by Shimadzu Corporation). In this state, compression molding is performed at a pressure of 1000 kg / cm ² to produce a tablet-shaped measurement sample.

  Next, the measurement sample is accommodated in the cylinder of the flow tester, and the temperature of the cylinder is gradually increased at a temperature increase rate of 4 ° C. per minute while applying a load of 30 kgf to the measurement sample. Then, the transition of the outflow rate is measured when the measurement sample melts and flows out of the cylinder through the pores of a die having a diameter of 1 mm and a length of 1 mm provided at the bottom of the cylinder. From the measured value, the transition of the melt viscosity with increasing temperature is obtained, and a graph of melt viscosity-temperature characteristics is created. From this graph, the melt viscosity at 105 ° C. is calculated.

  The toner includes toner particles and an external additive externally added to the toner particles. The external additive contains linear saturated fatty acid metal salt particles having 14 or more carbon atoms. By doing so, generation | occurrence | production of sleeve adhesion can be suppressed. This is because, by externally adding linear saturated fatty acid metal salt particles having 14 or more carbon atoms, the toner is easily detached from the developing sleeve during image formation, and prevents the toner from adhering to the developing sleeve. It is thought that it is possible.

  The linear saturated fatty acid metal salt particles are not particularly limited as long as they are linear saturated fatty acid metal salt particles having 14 or more carbon atoms. Moreover, when carbon number of the linear saturated fatty acid of the said linear saturated fatty acid metal salt particle is too small, there exists a tendency which cannot exhibit the effect which suppresses sleeve adhesion. Also, the carbon number may be large, but those having a carbon number exceeding 18 tend not to be used so much due to cost and the like. Specific examples of the linear saturated fatty acid metal salt particles include zinc stearate particles, magnesium stearate particles, and calcium stearate particles. Among these, zinc stearate particles are preferable.

  Moreover, as said external additive, what is necessary is just to contain the C14 or more linear saturated fatty acid metal salt particle | grains, and you may contain another external additive. The types of external additives and external additive addition methods will be specifically described later.

  The toner is preferably classified and adjusted in particle size so that the average particle size is about 5 to 10 μm. By adjusting the average particle diameter within the above-mentioned range, the occurrence of sleeve adhesion is further suppressed, and the occurrence of transfer dropout or the like tends to be further reduced. This is presumably because the ratio of the small particle size toner and the large particle size toner in the whole toner becomes small, and the contact friction coefficient with the photosensitive drum converges when viewed in the whole toner.

  Further, as described above, the toner includes toner particles and an external additive externally added to the toner particles.

<Toner particles>
The toner particles contain at least a binder resin and a colorant, and optionally contain a charge control agent, wax, and the like.

(Binder resin)
The binder resin can be used without particular limitation as long as it is conventionally used as a binder resin for toner particles. Specific examples thereof include, for example, styrene resins, acrylic resins, styrene-acrylic copolymers, polyethylene resins, polypropylene resins, vinyl chloride resins, polyester resins, polyamide resins, polyurethane resins, and polyvinyl resins. Thermoplastic resins such as alcohol resins, vinyl ether resins, N-vinyl resins and styrene-butadiene resins are preferably used.

  More specifically, examples of the polystyrene-based resin include not only a styrene homopolymer but also a copolymer of styrene and another copolymerizable monomer copolymerizable with styrene. Other copolymerization monomers include: p-chlorostyrene; vinyl naphthalene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl halides such as vinyl chloride, vinyl bromide and vinyl fluoride; vinyl acetate , Vinyl esters such as vinyl propionate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate , Phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and other (meth) acrylate esters; other acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; vinyl Vinyl ethers such as chill ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and methyl isopropenyl ketone; N such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidene -A vinyl compound etc. are mentioned. These can be copolymerized with a styrene monomer singly or in combination of two or more.

  Moreover, as a polyester-type resin, what is obtained by the condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component is used. The following are mentioned as a component used when synthesize | combining a polyester-type resin.

  First, as a divalent or trivalent or higher alcohol component, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1, Diols such as 4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, hydrogen Bisphenols such as added bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pe Taerythritol, 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.

  Next, the divalent or trivalent or higher carboxylic acid component includes a divalent or trivalent carboxylic acid, an acid anhydride thereof, or a lower alkyl ester thereof. Divalent carboxylic acids 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, isododecyl succinic acid, isodode Examples include alkyl or alkenyl succinic acid such as senyl succinic acid. Examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4- Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid , Tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empole trimer acid and the like.

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

  As the binder resin, it is preferable to use the thermoplastic resin as described above from the viewpoint of good fixability, but it is not necessary to use only the thermoplastic resin, and a crosslinking agent may be added or a thermosetting resin may be used. Some may be used. Thus, by introducing a partially crosslinked structure into the binder resin, it is possible to improve the storage stability, form retention, and durability of the toner without deteriorating the fixability.

  As the thermosetting resin as described above, for example, an epoxy resin or a cyanate resin can be used. More specifically, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyalkylene ether type epoxy resin, cycloaliphatic type epoxy resin, cyanate resin and the like can be mentioned. These may be used alone or 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 lower than 50 ° C., the toner obtained during use of the image forming apparatus is fused with each other in the developing device, or when the toner container is transported or stored in a warehouse. There is a tendency for the storage stability to deteriorate due to partial fusion between the two. Further, since the resin strength is low, there is a tendency that toner adheres to the photoreceptor. On the other hand, when the glass transition point is higher than 65 ° C., the low-temperature fixability of the toner tends to decrease. The glass transition point of the binder resin can be determined from the change point of specific heat using a differential scanning calorimeter (DSC). More specifically, a differential scanning calorimeter DSC-6200 manufactured by Seiko Instruments Inc. is used as a measuring device, 10 mg of a measurement sample is placed in an aluminum pan, an empty aluminum pan is used as a reference, and a measurement temperature range An endothermic curve is measured at 25 to 200 ° C. and a temperature rising rate of 10 ° C./min under normal temperature and humidity, and the glass transition point can be determined from the change point of the obtained endothermic curve.

(Coloring agent)
As the colorant, a known pigment or dye can be used so as to obtain a desired color as the toner. Specifically, for example, the following colorants may be mentioned depending on the color.
Examples of the black pigment include carbon black such as acetylene black, lamp black, and aniline black. Examples of yellow pigments include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, and Benzidine Yellow. GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. And CI Pigment Yellow 180. Examples of the orange pigment include reddish yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK and the like. Red pigments include Bengala, cadmium red, red lead, mercury cadmium sulfide, permanent red 4R, risor red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, Brilliant Carmine 3B, C.I. I. Pigment red 238 and the like. Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake. Examples of blue pigments include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, induslen blue BC, C.I. I. And CI Pigment Blue 15: 3 (copper phthalocyanine blue pigment). Examples of the green pigment include chrome green, chromium oxide, pigment green B, malachite green lake, and final yellow green G. Examples of white pigments include zinc white, titanium oxide, antimony white, zinc sulfide, barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. For example, as a colorant for cyan toner, C.I. I. Pigment Blue 15: 3 (copper phthalocyanine blue pigment) is preferred.

  The content of the colorant is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the binder resin in order to achieve a suitable image density.

(Charge control agent)
The charge control agent is blended in order to remarkably improve the charge level and charge rising characteristics (indicator of whether to charge to a constant charge level in a short time), and to obtain characteristics excellent in durability and stability. . That is, when the toner is positively charged for development, a positively chargeable charge control agent (positively chargeable charge control agent) can be added. When negatively charged for development, the toner is negatively charged. Charge control agent (negatively chargeable charge control agent) can be added.

  The charge control agent is not particularly limited as long as it is conventionally used as a charge control agent for toner particles.

  Specific examples of the positively chargeable charge control agent include, for example, 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-oxa Azine compounds such as triazine, phthalazine, quinazoline, quinoxaline; Azin Fast Red FC, Azin Fast Red 12BK, Azine Violet BO Direct dyes comprising azine compounds such as azine brown 3G, azine light brown GR, azine dark green BH / C, azine deep black EW, and azine black 3RL; nigrosine compounds such as nigrosine, nigrosine salt, nigrosine derivatives; nigrosine BK, nigrosine Examples include acid dyes composed of nigrosine compounds such as 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. These may be used alone or in combination of two or more. In particular, the nigrosine compound is optimal for use as a positively chargeable toner from the viewpoint of obtaining a quicker start-up property.

  Further, as the positively chargeable charge control agent, a quaternary ammonium salt, a carboxylate or a resin or oligomer having a carboxyl group as a functional group can be used. 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 Examples thereof include a resin, a styrene-acrylic resin having a carboxyl group, and a polyester resin having a carboxyl group. These may be used alone or in combination of two or more.

  In particular, a styrene-acrylic copolymer resin having a quaternary ammonium salt as a functional group is optimal from the viewpoint that the charge amount can be easily adjusted to a value within a desired range. In this case, preferred acrylic comonomers to be copolymerized with the styrene units include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, Examples include (meth) acrylic acid alkyl esters such as 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and iso-butyl methacrylate. As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate through a quaternization step is used. Examples of the derived dialkylaminoalkyl (meth) acrylate include di (amino) ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like ( Lower alkyl) aminoethyl (meth) acrylate; dimethylmethacrylamide and dimethylaminopropylmethacrylamide are preferably used. 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.

  As the charge control agent exhibiting negative chargeability, for example, organometallic complexes and chelate compounds are effective. Examples of the chelate compound include aluminum acetylacetonate, iron (II) acetylacetonate, chromium 3,5-di-tert-butylsalicylate, and the like. As the organometallic complex, an acetylacetone metal complex, a salicylic acid metal complex or a salt is preferable, and a salicylic acid metal complex or a salicylic acid metal salt is particularly preferable.

  The amount of the positively or negatively chargeable charge control agent described above is generally 0.5 to 15 parts by weight, preferably 0.5 to 8.0 parts by weight based on 100 parts by weight of the total amount of toner. Part, and most preferably 0.5 to 7.0 parts by weight. If the amount of the charge control agent added is too small, it tends to be difficult to stably charge the toner to a predetermined polarity, and image development is performed by developing the electrostatic latent image using the toner. The image density tends to be low, and it is difficult to maintain the image density constant. In addition, the charge control agent tends to be poorly dispersed, causing so-called fogging, and the contamination of the photoconductor tends to be severe. On the other hand, when the amount of the charge control agent added is too large, there is a tendency that environmental resistance, in particular, charging failure and image failure under high temperature and high humidity, and defects such as photoconductor contamination tend to occur.

(wax)
The wax is blended in order to improve fixability and offset property.

  The wax can be used without particular limitation as long as it is conventionally used as a wax for toner particles. Preferable examples include olefin waxes such as polyethylene wax and polypropylene wax, fluororesin waxes such as polytetrafluoroethylene wax, Fischer-Tropsch wax, paraffin wax, ester wax, montan wax, and rice wax. These waxes may be used alone or in combination of two or more. By adding such wax, offset property and image smearing can be more efficiently prevented.

  Although there is no restriction | limiting in particular in the compounding quantity of a wax, It is preferable that it is 1-5 mass parts with respect to 100 mass parts of whole quantity of a toner. When the blending amount of the wax is too small, there is a tendency that offset property and image smearing cannot be effectively prevented. On the other hand, when the amount of the wax is too large, the toners are fused with each other, and the storage stability tends to be lowered.

(Production method)
Further, the method for producing the toner particles is not particularly limited. For example, the toner particles can be produced as follows.

  First, each component of the toner particles such as the binder resin, the colorant, and the wax is mixed with a mixer or the like. As the mixer, a known one can be used, and examples thereof include a Henschel type mixing device such as a Henschel mixer, a super mixer, and a mechano mill, an ang mill, a hybridization system, and a cosmo system. Among these, a Henschel mixer is preferable.

  Next, the obtained mixture is melt-kneaded with a kneader or the like. A well-known thing can be used as said kneading machine, For example, extruders, such as a twin-screw extruder, a 3 roll mill, a lab blast mill, etc. are mentioned, An extruder is used suitably. Further, the temperature at the time of melt kneading is preferably a temperature that is not lower than the softening point of the binder resin and lower than the thermal decomposition temperature of the binder resin.

  Next, the obtained melt-kneaded product is cooled to form a solid, and the solid is pulverized by a pulverizer or the like. As the pulverizer, known pulverizers can be used. For example, an air pulverizer such as a jet pulverizer (jet mill) that pulverizes using a supersonic jet stream, a mechanical pulverizer such as a turbo mill, or an impact pulverizer. Examples thereof include a pulverizer, and a mechanical pulverizer, particularly a turbo mill, is preferably used.

  Finally, the obtained pulverized product is classified with a classifier or the like. By classification, excessively pulverized material and coarse powder can be removed, and desired toner particles can be obtained. As the classifier, known ones can be used, and examples thereof include a wind classifier such as a swirling wind classifier (rotary wind classifier) such as an elbow jet classifier, a centrifugal classifier, and the like. A machine, particularly an elbow jet classifier, is preferably used.

<External additive>
The toner is obtained by externally adding an external additive to the toner particles. That is, it is obtained by subjecting the toner particles to an external addition process.

  As the external addition step, any conventionally known external addition step can be used without limitation. Specifically, for example, a step of adding or fixing the external additive to the surface of the toner particles by adding the external additive to the toner particles and stirring the mixture with a stirrer or the like.

  As described above, the external additive only needs to contain linear saturated fatty acid metal salt particles having 14 or more carbon atoms, and is preferably composed of linear saturated fatty acid metal salt particles having 14 or more carbon atoms. Moreover, as said external additive, you may contain external additives other than a C14 or more linear saturated fatty acid metal salt particle with the C14 or more linear saturated fatty acid metal salt particle. The external additive other than the linear saturated fatty acid metal salt particles having 14 or more carbon atoms is not particularly limited as long as it can be used as an external additive for toner. Specific examples include metal oxide particles such as silica particles, titanium oxide particles, alumina particles, zinc oxide particles, and magnetite particles, resin particles, and the metal oxide particles. Among these, silica particles are preferable because they are excellent in fluidity, chargeability, and polishing properties. Moreover, as said external additive, the said external additive may be used independently, and may be used in combination of 2 or more type.

  In addition, the content of the external additive is preferably 3 to 5 parts by mass with respect to 100 parts by mass of the toner particles.

  As the stirrer, a conventionally known stirrer can be used without limitation. Specifically, for example, a general stirrer such as a turbine-type stirrer, a Henschel mixer, a supermixer or the like can be used, and a Henschel mixer is preferably used.

[Developer]
The developer containing the toner may be a one-component developer containing the toner and no carrier, or a two-component developer containing the toner and a magnetic carrier. Component developers are preferably used. Here, the two-component developer will be described. The developer according to another embodiment of the present invention includes the toner and a magnetic carrier.

<Magnetic carrier>
When the toner is used as a toner for a two-component developer, the toner is a non-magnetic toner, and the toner is mixed with a magnetic carrier.

  If the said magnetic carrier is conventionally used as a magnetic carrier of a developing agent, it can be especially used without a restriction | limiting. For example, it is possible to use a material in which the surface of a magnetic particle that is a carrier core material is coated with a resin. Specific examples of carrier core materials include magnetic metals such as iron, nickel and cobalt, alloys thereof, alloys containing rare earths, hematite, magnetite, manganese-zinc ferrite, nickel-zinc ferrite, manganese- Examples include magnetic particles produced by sintering and atomizing magnetic materials such as magnesium ferrite, soft ferrite such as lithium ferrite, iron oxide such as copper-zinc ferrite, and mixtures thereof. It is done.

  Examples of the surface coating agent for covering the surface of the carrier core material obtained as described above include fluorine-based binder resins such as polytetrafluoroethylene, polychlorotrifluoroethylene, and polyvinylidene fluoride.

The particle diameter of the carrier is generally preferably in the range of 20 to 200 [mu] m, more preferably in the range of 30 to 150 [mu] m, expressed in terms of particle diameter by electron microscopy. When the carrier material is mainly composed of a magnetic material, the apparent density of the carrier varies depending on the composition of the magnetic material, the surface structure, and the like, but is generally preferably in the range of 2.4 to 3.0 g / cm ³ .

  The toner concentration in the two-component developer containing the toner and the carrier is 1 to 20% by mass. Preferably it is 3-15 mass%. If the toner density is too low, the image density tends to be too thin. On the other hand, when the toner concentration is too high, toner scattering occurs in the developing device, and there is a possibility that the toner adheres to background portions such as in-machine dirt and transfer paper.

  The developer according to the exemplary embodiment is a two-component developer obtained by mixing the toner with the magnetic carrier at an appropriate ratio, and can be used, for example, in an image forming apparatus described later.

[Toner set]
The toner set according to the present embodiment forms a toner image using a plurality of colors of toner, and fixes the formed toner image on a recording medium to thereby form a plurality of colors used in an image forming method for forming an image. In the toner set comprising toner, the plurality of color toners are the electrostatic latent image developing toners, respectively, and the standard deviation of all the values from D4 to D8 in the plurality of color toners is 0.004. It is characterized by the following.

  Specifically, for example, when a toner image composed of a plurality of layers is formed by overlapping toners in the order of magenta toner, cyan toner, yellow toner, and black toner, these four types of toner are all the toners. The toner set in which the standard deviation of all the values from D4 to D8 of each color toner is 0.004 or less. That is, it is a toner set in which the shape of the toner is aligned to the same degree of circularity regardless of the color. By using such a toner set, the occurrence of sleeve adhesion can be suppressed, and a high-quality color image can be formed over a long period of time.

  Here, the standard deviation σ is a value calculated by the following formula (1).

Wherein, sigma represents the standard deviation, n is indicates the number of samples subject (toner) for calculating the standard deviation, x _i represents the values of D8 from D4 for color toners, the following ( What is represented by 2) represents an arithmetic average value (arithmetic average value) of all D4 to D8 of each color toner.

  Note that in the case of a toner set composed of four color toners of black toner, magenta toner, yellow toner, and cyan toner, the number of samples is 5, so n is 20.

[Developer set]
The developer set including the toners of the respective colors constituting the toner set is composed of a plurality of color developers. The developer of the plurality of colors may be a developer set composed of a single-component developer that includes each color toner constituting the toner set and does not include a carrier. A developer set comprising a two-component developer containing a carrier may be used, but a developer set comprising a two-component developer is preferably used. Specifically, for example, when the toner set is composed of magenta toner, cyan toner, yellow toner, and black toner, the developer set composed of the two-component developer includes the magenta toner and the magnetic carrier. A magenta developer containing, a cyan developer containing the cyan toner and a magnetic carrier, a yellow developer containing the yellow toner and a magnetic carrier, and a black developer containing the black toner and a magnetic carrier. It consists of. As the magnetic carrier, the same magnetic carrier as that contained in the developer can be used.

  The developer of the developer set according to the present embodiment includes, for example, a two-component developer in which the toner is mixed with the magnetic carrier at an appropriate ratio as described above. Can be used in

[Image forming apparatus]
An image forming apparatus using the toner, developer, toner set, and developer set will be described.

  FIG. 1 is a schematic cross-sectional view showing the overall configuration of the image forming apparatus used in the present embodiment. The image forming apparatus 1 is an apparatus that forms a predetermined image on a recording sheet sent out from a sheet feeding cassette 22 by electrophotography. In the image forming apparatus main body 2 of the image forming apparatus 1, the image forming unit 3 for black, the image forming unit 4 for yellow, the image forming unit 5 for cyan and the magenta image are formed horizontally from left to right in FIG. Image forming units 6 are arranged in order.

  FIG. 2 is a schematic cross-sectional view showing a configuration of an image forming unit provided in the image forming apparatus shown in FIG. The image forming unit 3 shown in FIG. 2 includes a photosensitive drum 10, a charging device 12, an exposure device 14, a developing device 100, a transfer device 16, and a cleaning device 18 in the same manner as the other image forming units 4, 5, and 6. ing. In the image forming apparatus 1, a vertical developing device 100 is disposed obliquely above the photosensitive drum 10 in order to reduce the size.

  The photoreceptor drum 10 is an organic photoreceptor (OPC). The charging device 12 includes a charging roller, and applies a predetermined potential to the surface of the photosensitive drum 10 by applying a voltage to the charging roller. The exposure device 14 irradiates light based on image data to selectively attenuate the surface potential of the photosensitive drum 10 to form an electrostatic latent image. The developing device 100 develops the electrostatic latent image formed on the surface of the photosensitive drum 10 with toner to form a toner image. The transfer device 16 primarily transfers the toner image formed on the photosensitive drum 10 to the intermediate transfer belt 20. The cleaning device 18 is for removing toner remaining on the surface of the photosensitive drum 10 after the primary transfer.

  The image forming apparatus 1 further includes a fixing device 24 having a heating roller and a pressure roller on the downstream side in the conveyance direction of the recording paper. The fixing device 24 applies heat and pressure to the recording paper on which the toner image is secondarily transferred to fix the toner image, thereby forming a predetermined image on the recording paper.

  Hereinafter, the developing device 100 used in the image forming apparatus 1 will be described with reference to FIG.

  The developing device 100 includes a housing 110 that contains a two-component developer containing a magnetic carrier and a non-magnetic toner, and a stirring roller 122 that rotates spiral blades in the first and second developer stirring chambers 112 and 114, respectively. , 124, agitating and conveying means 120 for agitating and conveying the contained two-component developer, a magnetic roller 130 for magnetically holding and conveying the developer on the peripheral surface, a magnetic roller 130, and a photosensitive drum And a developing roller 140 that is disposed at a predetermined interval with respect to each of the peripheral surfaces of 10 and to which only toner adheres. The agitating / conveying means 120, the magnetic roller 130, and the developing roller 140 are rotatably disposed in the housing 110, respectively.

  The agitation rollers 122 and 124 rotate the spiral blades and agitate the two-component developer in the opposite directions to charge the toner of the two-component developer. Further, the agitation roller 122 supplies a two-component developer containing charged toner and a carrier to the magnetic roller 130. The magnetic roller 130 conveys the two-component developer by adsorbing the two-component developer so as to form spikes by a magnet 134 disposed therein. At this time, the two-component developer becomes a magnetic brush by a magnet inside the magnetic roller 130, and when the magnetic brush passes between the layer thickness regulating blade 117 and the magnetic roller 130, the thickness of the magnetic brush is increased. Is regulated. The developing roller 140 disposed below the magnetic roller 130 comes into contact with the two-component developer spiked on the magnetic roller 130, so that the toner in the magnetic brush can be easily applied to the peripheral surface of the developing roller 140. Can be migrated. The toner can also be transferred from the magnetic roller 130 to the developing roller 140 by the action of the potential difference between the bias voltages applied to the magnetic roller 130 and the developing roller 140. By this transition, a thin layer of toner is formed on the peripheral surface of the developing roller 140. The toner forming a thin layer on the developing roller 140 is subjected to a potential difference generated between the photosensitive drum 10 and the developing roller 140 when the toner is conveyed to the vicinity of the photosensitive drum 31. Fly to 31.

  Through the image forming operation described above, the developing device 100 performs development based on the electrostatic latent image formed on the photosensitive drum 10.

  In the developing device 100, the carrier is not consumed by the development, but is collected in the developing device 100 as it is, and is mixed with the toner again and used. On the other hand, a toner container 100A mounted above the developing device 100 replenishes toner consumed by development.

  Although the compact tandem type image forming apparatus is compact, it has excellent high-speed performance and employs a non-contact developing type developing device in which the magnetic brush does not contact the photosensitive drum, so that the carrier adheres to the photosensitive member. In addition, the photoconductor is not damaged by the magnetic brush, and high image quality is possible.

  The above image forming apparatus is an apparatus that once transfers a plurality of color toner images to an intermediate transfer belt and transfers the plurality of color toner images transferred to the intermediate transfer belt onto a sheet. It is not limited to a device. For example, an image forming apparatus that directly transfers a toner image onto a sheet may be used.

  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.

  Here, the average circularity of the toner having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm and the melt viscosity (viscosity at 105 ° C.) of the toner are values measured as follows.

  First, the average circularity Dn of a toner having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm is a value measured as follows.

  First, a toner (a toner for measuring the average circularity Dn) as a measurement object was charged into a flow type particle image analyzer (FPIA-3000, manufactured by Sysmex Corporation). A two-dimensional projection image of a toner (where n is an integer greater than or equal to n) having a projected area equivalent circle diameter of not less than n μm and less than n + 1 μm out of all the charged particles is obtained in an environment of 23 ° C. and 60% RH. Measured with That is, the measurement object was limited to a toner having a projected area equivalent circle diameter of n μm or more and less than n + 1 μm, and a two-dimensional projection image was measured in an environment of 23 ° C. and 60% RH. Then, the obtained two-dimensional projection image (two-dimensional projection image for each toner with the projected area equivalent circle diameter limited) is obtained with an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). The perimeter (L) when the image was processed was measured. Next, the circularity of each toner was calculated using the perimeter (L0) of a circle having the same area as the two-dimensional projection image and the following formula (I).

a = L0 / L (I)
In the formula, a represents the circularity, L represents the perimeter when the two-dimensional projection image is image-processed, and L0 represents the perimeter of a circle having the same area as the two-dimensional projection image.

  Finally, a value obtained by dividing the sum of the circularity a of individual toners limited to the projected area circle equivalent diameter by the number of toners having the projected area circle equivalent diameter of n μm or more and less than n + 1 μm is an average circularity of a particle size of n μm. It was defined as Dn.

  Then, out of all the electrostatic latent image developing toners loaded in the flow type particle image analyzer, first, the object of measurement is limited to toners having a projected area circle equivalent diameter of 4 μm or more and less than 5 μm, and D4 Asked. Similarly, D5, D6, D7, and D8 were obtained.

Next, the viscosity at 105 ° C. is a value measured using a flow tester. As a flow tester, CFT-500D manufactured by Shimadzu Corporation was used. Specifically, first, 2 g of electrostatic latent image developing toner, which is a measurement object, is weighed and used for compression molding having an inner diameter corresponding to the inner diameter of a cylinder of a flow tester (CFT-500D manufactured by Shimadzu Corporation). In a state filled in the mold, compression molding was performed at a pressure of 1000 kg / cm ² to prepare a tablet-shaped measurement sample.

  Next, the measurement sample was accommodated in a cylinder of the flow tester, and the temperature of the cylinder was gradually increased at a rate of temperature increase of 4 ° C. per minute while applying a load of 30 kgf to the measurement sample. Then, the transition of the outflow speed was measured when the measurement sample melted and flowed out of the cylinder through the pores of a 1 mm diameter and 1 mm long die provided at the bottom of the cylinder. From the measured value, the transition of the melt viscosity with increasing temperature was determined, and a graph of melt viscosity-temperature characteristics was created. From this graph, the melt viscosity at 105 ° C. was calculated.

[Example A]
In Example A, the electrostatic latent image developing toner according to the present embodiment, particularly black toner, and a developer containing the electrostatic latent image developing toner were studied as examples.

<Example 1>
(Binder resin)
First, a method for producing a binder resin will be described.

  A raw material monomer consisting of 1960 g of a propylene oxide adduct of bisphenol A, 780 g of an ethylene oxide adduct of bisphenol A, 257 g of dodecenyl succinic anhydride, and 770 g of terephthalic acid is placed in a reaction vessel together with 4 g of dibutyltin oxide. Stir at 235 ° C. for 8 hours. Furthermore, it stirred for 1 hour on the conditions of 8.3 kPa. Thereafter, at 180 ° C., trimellitic anhydride is added into the reaction vessel so that the acid value of the resulting polyester resin becomes a desired value, and the temperature is raised to 210 ° C. at a rate of 10 ° C./hour. While stirring. By doing so, a polyester resin having an acid value of 20 mgKOH / g was obtained. The obtained polyester resin was used as a binder resin.

(Toner particles)
Next, a method for producing toner particles will be described.

  First, 100 parts by mass of the polyester resin as a binder resin, 5 parts by mass of carbon black (MA-100 manufactured by Mitsubishi Chemical Corporation) as a colorant, and carnauba wax (carnauba wax 1 manufactured by Hiroyuki Kato Co., Ltd.) as a wax. No.) 5 parts by mass and 2 parts by mass of a quaternary ammonium salt compound (P-51 manufactured by Orient Chemical Co., Ltd.) as a charge control agent were mixed using a Henschel mixer (FM20B manufactured by Nippon Coke Industries, Ltd.). Thereafter, the obtained mixture was melt-kneaded at 150 ° C. with a twin-screw extruder (TEM 45 manufactured by Toshiba Machine Co., Ltd.), and the obtained kneaded product was cooled. The cooled kneaded product was pulverized with a mechanical pulverizer (turbo mill manufactured by Turbo Industry Co., Ltd.), and classified with an elbow jet classifier (EJ-LABO manufactured by Nittetsu Mining Co., Ltd.). By doing so, toner particles having a volume average particle diameter of 6.8 μm were obtained. The volume average particle diameter of the toner particles was measured with a particle size meter (Multisizer 3 manufactured by Beckman Coulter, Inc.).

(toner)
Next, a toner manufacturing method will be described.

  First, with respect to 100 parts by mass of the obtained toner particles, 1.8 parts by mass of hydrophobic silica particles (REA200 manufactured by Nippon Aerosil Co., Ltd.) and titanium oxide particles (EC- 100) 1.0 part by mass and 0.1 part by mass of zinc stearate particles (manufactured by NOF Corporation) are added, and a rotating peripheral speed of 30 m / s is used for 5 minutes using a Henschel mixer (manufactured by Nippon Coke Industries, Ltd.). Stir and mix. By doing so, the electrostatic latent image developing toner (black toner) according to Example 1 was obtained.

  With respect to the electrostatic latent image developing toner, each value from D4 to D8 was measured to obtain Dmax and Dmin. And the viscosity in 105 degreeC was measured. Table 1 shows the viscosity at D4 to D8, Dmax, Dmin, Dmax-Dmin, and 105 ° C.

(Developer)
The obtained toner is used in a ratio of 10 parts by mass per 100 parts by mass of ferrite carrier (Powder Tech Co., Ltd .: carrier used in FS-C5016 manufactured by Kyocera Mita Co., Ltd.), that is, the toner concentration is 10% by mass Blended into And it stirred for 30 minutes with the ball mill (made by Kyocera Mita Co., Ltd.). By doing so, a two-component developer containing the electrostatic latent image developing toner according to Example 1 was obtained.

<Examples 2-6 and Comparative Examples 1-8>
In the production of the toner particles, the same procedure as in Example 1 was performed except that the melt-kneading conditions, the pulverizing conditions, and the classification conditions were changed so that Dmax, Dmin, and Dmax-Dmin were the values shown in Table 1. Each toner according to Examples 2 to 6 and Comparative Examples 1 to 8 and a two-component developer containing each toner were manufactured.

<Example 7>
In the production of the toner particles, the melt-kneading conditions, the pulverization conditions and the classification conditions are changed so that Dmax, Dmin, and Dmax-Dmin are the values shown in Table 1, and instead of zinc stearate particles, magnesium stearate A toner according to Example 7 and a two-component developer containing the toner were manufactured in the same manner as Example 1 except that the particles were used.

<Comparative Example 9>
In the production of the toner particles, the melt kneading conditions, the pulverizing conditions, and the classification conditions are changed so that Dmax, Dmin, and Dmax-Dmin are the values shown in Table 1, and further, zinc stearate particles are used as external additives. A toner according to Comparative Example 9 and a two-component developer containing the toner were produced in the same manner as in Example 1 except that the toner was not used.

<Comparative Example 10>
In the production of the toner particles, the melt kneading conditions, the pulverizing conditions and the classification conditions are changed so that Dmax, Dmin, and Dmax-Dmin are the values shown in Table 1, and zinc laurate is used instead of zinc stearate particles. A toner according to Comparative Example 10 and a two-component developer containing the toner were manufactured in the same manner as in Example 1 except that the particles were used.

  Table 1 shows the viscosity of each toner at Dmax, Dmin, Dmax−Dmin, and 105 ° C.

[Evaluation]
The obtained toner and developer were evaluated by the following methods.

<Transferability (slowness)>
First, instead of the charging device provided in the printer (FS-C5016N) manufactured by Kyocera Mita Co., Ltd., a modified machine equipped with a charging device equipped with a charging roller was used as an evaluation machine, and the obtained developers were started. Using each obtained toner as a replenishing toner, an image was formed in a normal temperature and humidity environment at a temperature of 20 to 23 ° C. and a relative humidity of 50 to 65% RH. went.

  Specifically, first, the start developer was set in a developer container corresponding to each color of the evaluation machine, and the evaluation machine was turned on and stabilized. Thereafter, a sample image including a 100% solid portion, a 50% halftone portion, a character portion, and a fine line portion was output under a normal temperature and humidity environment. This image was used as the initial image. After that, 20000 sheets of standard patterns with a printing rate of 5% were printed (20000 sheets withstand printing) in a normal temperature and humidity environment. Then, after the printing durability, the sample image was output again. This image was used as an image after printing (evaluation image).

  Whether or not there is a hollow in the thin line portion of the evaluation image was visually confirmed using a 10 × magnifying glass. If the void is not confirmed, it is evaluated as “5”. If the void is confirmed slightly (very lightly), it is evaluated as “4”, and many voids occur. If it can be confirmed, it is evaluated as “3”, and if it is confirmed that the void is remarkably generated, it is evaluated as “2”, and the void is remarkably generated in a wide range. When it was confirmed that this was done, it was evaluated as “1”. In addition, 4 or more was set to pass (within tolerance), and 3 or less was set to fail.

<Image density>
A 100% solid part (printing rate 100%) of the initial image and an image density of the post-printing image (evaluation image) were measured using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.). . Each was set as an image density ID (initial) and an image density ID (printing durability).

<Sleeve adhesion>
At an appropriate time, such as during the image formation or after outputting the post-printing image (evaluation image), it is visually checked whether toner is attached to the developing sleeve (developing roller), and at the same time, the evaluation Images were evaluated visually.

  After outputting the post-printing image (evaluation image), toner adhesion, that is, so-called sleeve adhesion, cannot be confirmed on the developing sleeve, and both the 100% solid portion and 50% halftone portion images of the evaluation image are good. If formed, it was evaluated as “5”.

  After outputting the post-printing image (evaluation image), toner adhesion (sleeve adhesion) can be slightly confirmed on the developing sleeve, but both the 100% solid portion and 50% halftone portion images of the evaluation image are good. If it was formed, it was evaluated as “4”.

  After outputting the post-printing image (evaluation image), it can be confirmed that much toner adhesion (sleeve adhesion) has occurred on the developing sleeve, and the 100% solid portion and 50% halftone portion of the evaluation image. When an image defect that seems to be caused by the adhesion of the sleeve, that is, a so-called non-uniformity of the sleeve layer, was confirmed in the image of, the evaluation was “3”.

  It can be confirmed that a large amount of toner adhesion (sleeve adhesion) has occurred on the developing sleeve between the output of the initial image and the output of the post-printing image (evaluation image). In the images of the 100% solid portion and the 50% halftone portion, an image defect that seems to be derived from the adhesion of the sleeve, that is, so-called sleeve layer unevenness, was evaluated as “2”.

  After the initial image is output, it can be confirmed that a large amount of toner adheres (sleeve adherence) to the developing sleeve, and the sleeve adheres to the 100% solid portion and 50% halftone portion images of the initial image. When the image defect that seems to be derived from the image, that is, the so-called sleeve layer unevenness was confirmed, it was evaluated as “1”.

  In addition, 4 or more was set to pass (within tolerance), and 3 or less was set to fail.

<Fixability>
Set the fixing temperature to 180 ° C, cool for 10 minutes with the power off in the normal environment (20 ° C, 65% RH), turn on the power, and print five fixed pattern solid images continuously for measurement. I got an image. Then, a brass weight (1 kg) wrapped with a cotton cloth was placed on the measurement image. Thereafter, the evaluation image was rubbed 10 times with the weight while the weight of the weight was applied to the evaluation image. The image density of the solid part before and after this operation was measured with the reflection densitometer. Then, the fixing rate was calculated from the following formula (II) to evaluate the fixing property.

Fixing rate (%) = image density after the operation / image density before the operation × 100 (II)
When the fixing rate is 95% or more, it is evaluated as “◯”, when the fixing rate is 90% or more and less than 95%, it is evaluated as “Δ”, and when the fixing rate is less than 90%, “ “×”.

  In addition, "(circle)" and "(triangle | delta)" were set to pass (within tolerance), and "x" was set to disqualify.

<Hot offset property>
Under normal environment (20 ° C., 65% RH), the fixing temperature was set to 230 ° C., and 10 offset pattern images were printed continuously to obtain a measurement image. It was visually confirmed whether or not an image defect thought to be caused by hot offset occurred in the measurement image.

  If the occurrence of an image defect that seems to be caused by a hot offset was not confirmed, it was evaluated as “◯”, and if the occurrence of an image defect that was thought to be caused by a hot offset was confirmed, it was evaluated as “x”. In addition, "(circle)" was set as the pass (within tolerance), and "x" was set as the failure.

<Cleanability>
First, the same image forming apparatus as used in each evaluation is used as an evaluator, image data is transmitted to the evaluator, image formation is started under the same conditions as in each evaluation, and cleaning is performed. The driving of the photosensitive drum was stopped while the toner on the surface of the photosensitive drum was being removed by the apparatus.

  Specifically, image data for outputting a sample image including a blank paper portion 31 and a belt-like solid image portion 32 as shown in FIG. 3 is transmitted to the evaluator, and as shown in FIG. A solid image portion region 42 to which toner for forming the belt-like solid image portion in the circumferential direction was adhered was formed in the central portion of the body drum 40. Thereafter, the driving of the photosensitive drum was stopped while the toner on the surface of the photosensitive drum was being removed by the cleaning device. That is, as shown in FIG. 4, the surface of the photosensitive drum 40 has a blank paper portion area 41 to which toner corresponding to the blank paper portion is not attached and a solid to which toner corresponding to the solid image portion is attached. An image area 42 and a post-toner removal area 43 in a state where the attached toner is removed by the cleaning device are formed. FIG. 3 is a conceptual diagram showing an image for cleaning performance evaluation, and FIG. 4 is a schematic diagram showing the state of the photosensitive drum when the cleaning performance is evaluated.

  Then, a cellophane adhesive tape was applied to the post-toner removal area 43 and then peeled off. The peeled cellophane adhesive tape was adhered to white paper. The density of the paper on which the cellophane adhesive tape was adhered was measured from above the cellophane adhesive tape using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.).

  When the concentration was 0.14 or less, it was evaluated as “◯”, and when the concentration exceeded 0.14, it was evaluated as “Δ”. In addition, when the same measurement as described above is performed using a photosensitive drum having no toner attached to the surface, the density is 0.10 to 0.14. Therefore, “◯” was accepted (within the allowable range), and “Δ” was rejected.

  The results are shown in Table 2.

As shown in Table 2, Dmin is 0.94 or more, the difference between Dmax and Dmin is 0.015 or less, and the viscosity at 105 ° C. is 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s. In addition, when the external additive contains linear saturated fatty acid metal salt particles having 14 or more carbon atoms (Examples 1 to 7), compared to other cases (Comparative Examples 1 to 10), It shows that a high-quality image can be formed by attaching the sleeve.

[Example B]
In Example B, the toner set and developer set according to this embodiment were taken as an example and studied. The toner set according to this embodiment is a toner set including black toner, cyan toner, magenta toner, and yellow toner, but is not limited thereto.

<Examples 8 to 10 and Comparative Examples 11 to 15>
(Black toner)
In the production of the toner particles, the standard deviation Dσ of all D4 to D8 of D4 to D8, Dmax−Dmin, and black toner, cyan toner, magenta toner, and yellow toner is set to the values shown in Table 3 and Table 4. In addition, the black toner contained in each of the toner sets according to Examples 8 to 10 and Comparative Examples 11 to 15, and each of the above, except that the melt kneading conditions, the pulverizing conditions, and the classification conditions were changed A two-component developer containing black toner was produced.

(Cyan toner)
In the production of the toner particles, instead of 5 parts by mass of carbon black (MA-100 manufactured by Mitsubishi Chemical Corporation), 3 parts by mass of a phthalocyanine pigment (CI pigment blue 15: 1 manufactured by Sanyo Dye Co., Ltd.) was used. , D4 to D8, Dmax-Dmin, and melt kneading conditions so that the standard deviation Dσ of all of D4 to D8 of black toner, cyan toner, magenta toner, and yellow toner becomes the values shown in Tables 3 and 4. Except for changing pulverization conditions and classification conditions, in the same manner as in Example 1, cyan toner included in each toner set according to Examples 8-10 and Comparative Examples 11-15, and two components including each cyan toner A developer was produced.

(Magenta toner)
In the production of the toner particles, 4 parts by mass of quinacridone pigment (CI Pigment Red 122, Sanyo Dye Co., Ltd.) is used instead of 5 parts by mass of carbon black (MA-100 manufactured by Mitsubishi Chemical Corporation). ~ D8, Dmax-Dmin, and melt kneading conditions and pulverizing conditions so that the standard deviation Dσ of all D4 to D8 of black toner, cyan toner, magenta toner, and yellow toner becomes the values shown in Tables 3 and 4 And magenta toner contained in each toner set according to Examples 8 to 10 and Comparative Examples 11 to 15 and a two-component developer containing each magenta toner in the same manner as Example 1 except that the classification conditions were changed Manufactured.

(Yellow toner)
In the production of the toner particles, 4 parts by mass of phthalocyanine pigment (CI Pigment Yellow 180, Sanyo Dyeing Co., Ltd.) was used instead of 5 parts by mass of carbon black (MA-100 manufactured by Mitsubishi Chemical Corporation). ~ D8, Dmax-Dmin, and melt kneading conditions and pulverizing conditions so that the standard deviation Dσ of all D4 to D8 of black toner, cyan toner, magenta toner, and yellow toner becomes the values shown in Tables 3 and 4 In addition, the yellow toner included in each toner set according to Examples 8 to 10 and Comparative Examples 11 to 15 and the two-component developer including each yellow toner are the same as Example 1 except that the classification conditions are changed Manufactured.

<Comparative Example 16>
When producing black toner, cyan toner, magenta toner, and yellow toner, the linear saturated fatty acid metal salt particles having 14 or more carbon atoms are not used as an external additive. The melt-kneading conditions, the pulverizing conditions, and the D8, Dmax-Dmin, and the standard deviation Dσ of all of D4 to D8 of the black toner, cyan toner, magenta toner, and yellow toner are the values shown in Tables 3 and A toner set according to Comparative Example 16 and a developer set including each toner of the toner set were manufactured in the same manner as in Examples 8 to 10 and Comparative Examples 11 to 15 except that the classification conditions were changed.

  Tables 3 and 4 show D4-D8, Dmax-Dmin, standard deviation Dσ, and viscosity at 105 ° C. of each toner set. Since the toners constituting the toner set have the same composition other than the colorant, the viscosity at 105 ° C. is the same regardless of the color of the toner.

[Evaluation]
The obtained toner set and developer set were evaluated by the following methods. Note that the transferability (blank), image density, sleeve adhesion, fixability, and hot offset property were evaluated in the same manner as described above.

<Transferability (secondary color)>
When the post-printing image (evaluation image) is formed with secondary colors of red, blue, and green, whether there is a hollow in the thin line portion of the evaluation image, using a 10 times magnifier, It was confirmed visually. If the void is not confirmed, it is evaluated as “5”. If the void is confirmed slightly (very lightly), it is evaluated as “4”, and many voids occur. If it can be confirmed, it is evaluated as “3”, and if it is confirmed that the void is remarkably generated, it is evaluated as “2”, and the void is remarkably generated in a wide range. When it was confirmed that this was done, it was evaluated as “1”. In addition, 4 or more was set to pass (within tolerance), and 3 or less was set to fail.

<Color image color reproducibility>
When the initial image and the post-printing image (evaluation image) are formed with secondary colors such as red, blue, and green, the 100% solid portion of the initial image and the post-printing image (evaluation image) ) Was measured for the color difference from the 100% solid part.

  Here, the color difference is a value obtained as follows.

L ^* value, a ^* value, and b when the 100% solid part of the initial image and the 100% solid part of the post-printing image (evaluation image) are represented by the L ^* a ^* b ^* method, respectively. ^* Values were measured using a spectrophotometer (Spectro Eye manufactured by Gretag Macbeth). The values of the L ^* a ^* b ^* system (L ^* value, a ^* value, and b ^* value) are given in JIS Z 8729 “Color display method-L ^* a ^* b ^* display color and L ^* u It is a value obtained by a method based on “ ^* v ^* display color”.

  And the color difference ((DELTA) E) was computed using following formula (III).

ΔE = (ΔL ^{* 2} + Δa ^{* 2} + Δb ^{* 2} ) ^1/2 (III)
In the formula, ΔL ^* represents the difference between the 100% solid part of the initial image and the 100% solid part of the post-printing image (evaluation image) and the L ^* value, and Δa ^* is the 100% solid part of the initial image. And the difference between a ^* value and 100% solid part of the image after printing (evaluation image) and Δb ^* is 100% of the 100% solid part of the initial image and the image after printing (evaluation image) The difference between the solid part and the b ^* value is shown.

  Furthermore, a color image such as a human image was output, and the color image was visually observed.

  Then, from these measurements, if ΔE is 2 or less and the color image is confirmed to be very high definition, it is evaluated as “5”, and ΔE is more than 2 and 4 or less. Is confirmed to be high-definition, it is evaluated as “4”, and if ΔE is greater than 4 and less than or equal to 6 and a portion lacking in detail is confirmed in the color image, it is evaluated as “3”. , ΔE is more than 6 and less than or equal to 10 and if it is confirmed that the color image has no fineness, it is evaluated as “2”, and if ΔE exceeds 10 and disturbance is confirmed in the color image, 1 ”. In addition, 4 or more was set to pass (within tolerance), and 3 or less was set to fail.

  The results are shown in Table 5.

As shown in Table 5, Dmin is 0.94 or more, the difference between Dmax and Dmin is 0.015 or less, and the viscosity at 105 ° C. is 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s. Further, the external additive further includes an electrostatic latent image developing toner containing linear saturated fatty acid metal salt particles having 14 or more carbon atoms, and further, the standard deviation of all D4 to D8 values of each toner Is 0.004 or less (Examples 8 to 10), compared to other cases (Comparative Examples 11 to 16), it is possible to suppress sleeve adhesion and form a high-quality image. ing.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Image forming unit for black 10 Photosensitive drum 12 Charging apparatus 14 Exposure apparatus 16 Transfer apparatus 18 Cleaning apparatus 100 Developing apparatus 130 Magnetic roller 140 Developing roller

Claims (5)

A toner for developing an electrostatic latent image, comprising toner particles obtained by mixing, melting, kneading and then pulverizing toner particle raw materials, and an external additive externally added to the toner particles,
In the toner measured by the flow type particle image analyzer, when the average circularity of the toner whose projected area equivalent circle diameter is n μm or more and less than n + 1 μm is Dn,
The values from D4 to D8 are each 0.94 or more,
The difference (Dmax−Dmin) between the maximum value (Dmax) and the minimum value (Dmin) from D4 to D8 is 0.015 or less,
The viscosity at 105 ° C. is 3 × 10 ^{3 to} 7 × 10 ⁴ Pa · s,
The toner for developing an electrostatic latent image, wherein the external additive contains linear saturated fatty acid metal salt particles having 14 or more carbon atoms. A magnetic roller that carries and conveys a developer containing nonmagnetic toner and a magnetic carrier, and is arranged to face the magnetic roller at a predetermined interval, and carries the nonmagnetic toner in the developer on the peripheral surface. A developing roller to be conveyed, and an organic photoreceptor that is disposed to face the developing roller and forms an electrostatic latent image,
The non-magnetic toner in the developer conveyed by the magnetic roller is transferred to the peripheral surface of the developing roller, and the non-magnetic toner conveyed by the developing roller is caused to fly to the surface of the organic photoreceptor, In an image forming apparatus for forming an image by developing an electrostatic latent image formed in advance on the surface of an organic photoreceptor as a toner image and transferring the toner image to a recording medium.
The electrostatic latent image developing toner according to claim 1, which is used as the nonmagnetic toner. A developer comprising a non-magnetic toner and a magnetic carrier,
The developer according to claim 1, wherein the non-magnetic toner is the electrostatic latent image developing toner according to claim 1. A toner set comprising a plurality of color toners used in an image forming method for forming an image by forming a toner image using a plurality of color toners and fixing the formed toner image on a recording medium,
The toner of the plurality of colors is the electrostatic latent image developing toner according to claim 1 or 2, respectively.
A toner set, wherein a standard deviation of all values from D4 to D8 in the plurality of color toners is 0.004 or less. Consisting of multiple color developers
The developer set, wherein each of the plurality of color developers contains toner for developing electrostatic latent images of each color and a magnetic carrier constituting the toner set according to claim 4.

Images