JP2009025750A - Toner and method for manufacturing toner, two-component developer, developing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner and a method for manufacturing the toner free from filming, having preferable fixing property and transfer efficiency and giving an image of high picture quality, and to provide a two-component developer, a developing device and an image forming apparatus. <P>SOLUTION: The toner includes: a first group of toner particles containing at least a first binder resin having polarity, a first colorant and a first release agent having low polarity with respect to the first binder resin; and a second group of toner particles containing at least a second binder resin having polarity, a second colorant and a second release agent having high polarity with respect to the second binder resin, the second group having a volume average particle diameter smaller than that of the first group of toner particles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a toner used for developing a latent image, a manufacturing method thereof, a two-component developer, a developing device, and an image forming apparatus in an image forming apparatus such as an electrophotographic system or an electrostatic printing system.

  Toner that visualizes a latent image is used in various image forming processes, and as an example, it is known to be used in an electrophotographic image forming process.

  In an image forming apparatus using an electrophotographic image forming process, generally, a charging process for uniformly charging a photosensitive layer on a surface of a photosensitive member, which is a latent image carrier, and an original image on a charged photosensitive member surface An exposure process for projecting the signal light to form an electrostatic latent image, a developing process for supplying an electrophotographic toner to the electrostatic latent image on the surface of the photoreceptor to make it visible, and a toner image on the surface of the photoreceptor to paper, The transfer process for transferring to a recording medium such as an OHP sheet, the fixing process for fixing the toner image on the recording medium by heating, pressurizing, etc., and the toner remaining on the surface of the photoreceptor after the toner image transfer are removed by a cleaning blade. A cleaning process is performed to form a desired image on the recording medium. The transfer of the toner image to the recording medium may be performed via an intermediate transfer medium.

  As the developer used in such an image forming apparatus, there are a one-component developer mainly composed of toner and a two-component developer using a mixture of toner and carrier. In addition, as a method for producing the toner used in these developers, a kneading and pulverizing method is widely used in which a toner raw material containing a binder resin, a colorant, a release agent, a charge control agent, and the like is melt-kneaded and then pulverized and classified. ing.

  In recent years, in order to obtain a higher quality image in these image forming apparatuses, the toner constituting the developer has been reduced in particle size. Since the exposure rate is high, the occurrence of filming on the photosensitive member becomes a problem. However, if the dispersibility of the release agent in the entire toner is improved in order to suppress the occurrence of such filming, the fixability is deteriorated.

  There is also a problem in that the transfer efficiency deteriorates because the adhesion between the toner and the photosensitive member becomes stronger as the particle size of the toner becomes smaller.

  In order to solve such a problem, for example, in Patent Document 1, at least two kinds of toner particles having different average particle diameters are mixed and used, and the wax used for the small particle diameter toner is compared with the large particle diameter toner. There has been disclosed a technique for preventing the occurrence of filming on the photoreceptor and reducing the content or using a high softening point to obtain a high quality and clear image.

  In Patent Document 2, when the same type of release agent is used in a mixture of at least two types of toners having different average particle sizes, the release agent is contained in a large amount of toner and a small amount of toner in a small particle size. In addition, when changing the molecular weight of the release agent, a technique for obtaining a toner having excellent durability by incorporating a small particle toner with a high molecular weight and a large particle toner with a low molecular weight is disclosed. Has been.

Japanese Patent Laid-Open No. 7-261453 Japanese Patent Laid-Open No. 2-158748

  Since the technology for reducing the content of the release agent in the small particle size toner disclosed in Patent Documents 1 and 2 cannot sufficiently obtain the release effect in the small particle size toner, the micro offset in the high temperature range is reduced. May occur easily. Patent Document 1 discloses a technique of using a wax having a high softening point for a small particle diameter toner, and Patent Document 2 discloses a technique of using a release agent having a large molecular weight for the small particle diameter toner. However, these techniques cannot sufficiently prevent the occurrence of filming on the photoreceptor. Further, Patent Documents 1 and 2 do not solve the problem of deterioration in transfer efficiency due to the reduction in toner particle size.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a toner that does not cause filming, can improve fixability and transfer efficiency, and can obtain a high-quality image, and a manufacturing method thereof. To provide a two-component developer, a developing device and an image forming apparatus.

The present invention includes a first toner particle group including at least a first binder resin having polarity, a first colorant, and a first release agent having a low polarity with respect to the first binder resin;
A second binder resin having at least polarity, a second colorant, and a second release agent having a high polarity with respect to the second binder resin, and having a volume average particle diameter larger than that of the first toner particle group. And a small second toner particle group.

  In the toner of the present invention, the first and second binder resins have an acid value of 5 mgKOH / g or more.

  In the toner of the present invention, the first release agent has an acid value of less than 3 mgKOH / g, and the second release agent has an acid value of 3 mgKOH / g or more.

  The toner of the present invention is characterized in that the softening point of the first binder resin is higher than the softening point of the second binder resin.

  In the toner of the present invention, the first and second binder resins contain a polyester resin.

In the toner of the present invention, the first release agent has a melting point of 70 ° C. or lower.
The present invention is also a method for producing the toner,
First before producing the first mixture by mixing the first binder resin having at least polarity, the first colorant, and the first binder resin with the low-polarity first release agent. A mixing step;
A first melt-kneading step of producing a first melt-kneaded product by melt-kneading the first mixture;
A first pulverization step of pulverizing the first melt-kneaded product to produce a first pulverized product;
A first classification step of classifying the first pulverized product to produce a first toner particle group;
Second before producing the second mixture by mixing the second binder resin having at least polarity, the second colorant, and the second binder resin having a high polarity with the second binder resin. A mixing step;
A second melt-kneading step of melt-kneading the second mixture to produce a second melt-kneaded product;
A second pulverization step of pulverizing the second melt-kneaded product to produce a second pulverized product;
A second classification step of classifying the second pulverized product to produce a second toner particle group having a volume average particle size smaller than that of the first toner particle group;
A toner manufacturing method comprising a mixing step of mixing a first toner particle group and a second toner particle group.

  In the toner production method of the present invention, the volume average particle size of the first toner particle group is 4 μm or more and 7 μm or less, and the volume average particle size of the second toner particle group is 3 μm or more and 5 μm or less. And

Further, in the toner production method of the present invention, in the first premixing step, 4.0% by weight or more of the first release agent is mixed with the first mixture, and in the second premixing step, The release agent of 2 is mixed with 4.0% by weight or more with respect to the second mixture.
According to another aspect of the present invention, there is provided a two-component developer comprising the toner and a carrier.

In addition, the present invention is a developing device that performs development using the two-component developer.
The present invention also provides an image forming apparatus comprising the developing device.

  According to the present invention, the toner of the present invention includes a first binder resin having at least a polarity, a first colorant, and a first release agent having a low polarity with respect to the first binder resin. 1 toner particle group, and a second binder resin having at least polarity, a second colorant, and a second release agent having a high polarity with respect to the second binder resin. And a second toner particle group having a volume average particle size smaller than that of the group.

  As described above, in the first toner particle group having a large volume average particle diameter, a release agent having a low polarity with respect to the first binder resin and a low dispersibility with respect to the first binder resin is contained. By doing so, the release agent tends to exist on the surface of the toner particles. Therefore, the release agent can be easily oozed out during fixing, and fixing property, particularly low temperature fixing property can be improved. The second toner particle group having a small volume average particle diameter contains a release agent that is highly polar with respect to the polarity of the second binder resin and highly dispersible with respect to the second binder resin. Thus, the occurrence of filming can be suppressed, and the adhesion force of the toner to the photoreceptor can be reduced, so that the transfer efficiency can be improved.

  Therefore, the toner of the present invention includes the first toner particle group and the second toner particle group, so that the occurrence of filming can be suppressed, the fixing property and the transfer efficiency can be improved, and a high-quality image can be obtained. .

  According to the present invention, it is preferable that the first and second binder resins have an acid value of 5 mgKOH / g or more. Thereby, the occurrence of filming can be suppressed more reliably, the fixing property and the transfer efficiency can be improved, and a high-quality image can be obtained.

  According to the present invention, it is preferable that the first mold release agent has an acid value of less than 3 mgKOH / g, and the second mold release agent has an acid value of 3 mgKOH / g or more. Thereby, the occurrence of filming can be suppressed more reliably, the fixing property and the transfer efficiency can be improved, and a high-quality image can be obtained.

  According to the invention, the softening point of the first binder resin is preferably higher than the softening point of the second binder resin. As a result, the occurrence of filming can be further suppressed, the fixing property and the transfer efficiency can be further improved, and a higher quality image can be obtained.

  According to the invention, the first and second binder resins preferably contain a polyester resin. Thus, a toner having excellent durability and color developability can be obtained by including a polyester resin having excellent durability and transparency and a low softening point. Further, it is possible to obtain a toner having excellent low-temperature fixability that can be fixed at a lower temperature. Further, since the physical property values such as the acid value and the softening temperature can be easily adjusted, the occurrence of filming can be more easily suppressed, the fixing property and the transfer efficiency can be improved, and a high-quality image can be obtained.

  According to the invention, the first release agent preferably has a melting point of 70 ° C. or lower. As a result, it is possible to obtain a toner having better low-temperature fixability.

  According to the invention, the toner production method includes at least a first binder resin having a polarity, a first colorant, and a first release agent having a low polarity with respect to the first binder resin. A first premixing step of mixing to produce a first mixture, a first melt kneading step of melt-kneading the first mixture to produce a first melt-kneaded product, and a first melt-kneaded product A first pulverizing process for preparing a first pulverized product, a first classifying process for preparing a first toner particle group by classifying the first pulverized product, and a second having at least polarity. A second premixing step of preparing a second mixture by mixing a second release agent having high polarity with the binder resin, the second colorant, and the second binder resin; A second melt-kneaded step of melt-kneading the mixture to prepare a second melt-kneaded product, and pulverizing the second melt-kneaded product to obtain a second pulverized product. A second pulverizing step, a second pulverizing product, a second pulverized product, a second grading step of producing a second toner particle group having a volume average particle size smaller than that of the first toner particle group, A mixing step of mixing the first toner particle group and the second toner particle group.

  As a result, it is possible to produce the toner of the present invention that can suppress the occurrence of filming, improve the fixability and transfer efficiency, and obtain a high quality image.

  Further, according to the present invention, the volume average particle size of the first toner particle group is 4 μm or more and 7 μm or less, and the volume average particle size of the second toner particle group is 3 μm or more and 5 μm or less. The range of the particle size distribution of the obtained toner is 4 μm or more and 7 μm or less, so that toner scattering can be suppressed and a high-definition and high-resolution high-quality image can be obtained.

  According to the invention, in the first premixing step, 4.0% by weight or more of the first release agent is mixed with the first mixture, and in the second premixing step, the second release agent is mixed. It is preferable to mix 4.0% by weight or more of the mold with respect to the second mixture. As described above, by adjusting the mixing amount of the release agent in the first and second premixing steps within the above range, the effect of suppressing the occurrence of filming and the effect of improving the fixing property and the transfer efficiency are balanced. It is possible to adjust, and a higher quality image can be obtained.

  Further, according to the present invention, the two-component developer of the present invention comprises the toner of the present invention capable of suppressing filming, improving fixability and transfer efficiency, and obtaining a high-quality image, and a carrier. By including, the thermal aggregation of the two-component developer can be suppressed, and a high-quality image can be obtained stably over a long period of time.

  According to the invention, the developing device of the invention can form a high-definition and high-resolution toner image on the photoreceptor by performing development using the two-component developer.

  Further, according to the present invention, the image forming apparatus of the present invention is provided with the developing device, so that the occurrence of filming can be suppressed, the fixing property and the transfer efficiency can be improved, and a high-definition and high-resolution high-quality image can be obtained. Can be formed.

  The toner of the present invention includes a first toner particle group including at least a first binder resin having polarity, a first colorant, and a first release agent having a low polarity with respect to the first binder resin; , Containing at least a second binder resin having polarity, a second colorant, and a release agent having high polarity with respect to the second binder resin, and having a volume average particle size smaller than that of the first toner particle group And a second toner particle group.

  In the present invention, the presence / absence and level of polarity can be determined based on, for example, the amount of ionic groups contained in the binder resin and the release agent. That is, whether or not there is polarity and whether it is high or low can be determined based on whether the amount of the ionic group is larger or smaller than a certain standard.

  The amount of the ionic group can be determined by, for example, the acid value of the binder resin and the release agent. That is, the larger the acid value, the more ionic groups, and the smaller the acid value, the fewer ionic groups. The acid value can be measured by neutralization titration as follows. Dissolve 5 g of the sample in 50 mL of tetrahydrofuran (THF), add several drops of phenolphthalein ethanol solution as an indicator, and then titrate with 0.1 mol / L aqueous potassium hydroxide (KOH). The point at which the color of the sample solution changed from colorless to purple is used as the end point, and the acid value (mgKOH / g) is calculated from the amount of potassium hydroxide aqueous solution required to reach the end point and the weight of the sample subjected to titration. To do.

  The dispersibility of the release agent with respect to the binder resin depends on the polarities of the binder resin and the release agent. For polar binder resins, the dispersibility of the high-polarity release agent increases, The dispersibility of the low-polarity release agent is increased with respect to the binder resin that does not have the binder resin.

  Therefore, the first toner particle group having a large volume average particle size contains a release agent having a low polarity with respect to the first binder resin and a low dispersibility with respect to the first binder resin. Thus, the release agent functions as a grinding aid during toner grinding, and the release agent tends to exist at the toner grinding interface, that is, on the surface of the toner particles. Therefore, in the first toner particle group, it is possible to easily exude the release agent at the time of fixing, and it is possible to improve the fixing property, particularly the low temperature fixing property.

  On the other hand, the second toner particle group having a small volume average particle size contains a release agent that is highly polar with respect to the polarity of the second binder resin and highly dispersible with respect to the second binder resin. By doing so, it is possible to suppress the occurrence of filming in the second toner particle group, and it is possible to reduce the adhesion force of the toner to the photosensitive member, so that the transfer efficiency can be improved.

  By including the first toner particle group and the second toner particle group described above, the toner of the present invention can suppress filming, improve the fixability and transfer efficiency, and obtain a high-quality image. it can.

  The determination of the presence / absence of the polarity and the level of the polarity is not limited to the determination based on the amount of the ionic group contained in the binder resin and the release agent described above. For example, in the binder resin and the release agent The determination may be based on the content of atoms having a higher electronegativity than carbon contained in the carbon or the determination based on the solubility of the binder resin and the release agent in polar solvents such as acetone.

  The method for producing the toner of the present invention will be described below. FIG. 1 is a flowchart showing an example of the procedure of the toner production method of the present invention. As shown in FIG. 1, the toner manufacturing method of the present invention includes a first release resin having a low polarity with respect to at least a first binder resin having polarity, a first colorant, and a first binder resin. First premixing step (step S1) for preparing the first mixture by mixing the agent, and first melt kneading step (step for preparing the first melt-kneaded product by melt-kneading the first mixture S2), a first pulverization step (step S3) in which the first melt-kneaded product is pulverized to produce a first pulverized product, and the first pulverized product is classified to produce a first toner particle group. The first classification step (step S4), and at least the second binder resin having polarity, the second colorant, and the second binder resin with high polarity are mixed. A second premixing step (step S5) for producing the second mixture, and the second mixture is melt-kneaded to produce the second mixture A second melt-kneading step (step S6) for producing a melt-kneaded product, a second pulverizing step (step S7) for producing a second crushed product by pulverizing the second melt-kneaded product, a second A second classification step (step S8) for classifying the pulverized product to produce a second toner particle group having a volume average particle size smaller than that of the first toner particle group, and the first toner particle group and the second toner particle group A mixing step (step S9) of mixing the toner particle groups.

  Below, each manufacturing process of step S1-step S9 is demonstrated in detail. The manufacturing process from step S1 to step S4 for producing the first toner particle group and the manufacturing process from step S5 to step S8 for producing the second toner particle group are performed simultaneously. Either manufacturing process may be performed first. Production of the toner of the present invention is started by moving from step S0 to step S1 or step S5, or from step S0 to step S1 and step S5.

[First and second premixing steps]
In the first premixing step of step S1, a low-polarity first release agent is mixed with a mixer with respect to at least the first binder resin having polarity, the first colorant, and the first binder resin. Dry mix to make the first mixture. In the second premixing step of step S5, a second release agent having a low polarity is used for at least the second binder resin having polarity, the second colorant, and the second binder resin. The second mixture is prepared in the same manner as in the first premixing step. Hereinafter, “first and second binder resin”, “first and second colorant” and “first and second release agent” are simply referred to as “binder resin”, “colorant” and Sometimes referred to as “release agent”.

  The first and second mixtures may contain other toner additive components in addition to the binder resin, the colorant, and the release agent. Examples of other toner additive components include a charge control agent.

  Known mixers can be used for dry mixing. For example, Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), mechano mill (trade name) Henschel-type mixing equipment such as Okada Seiko Co., Ltd., Ongmill (trade name, manufactured by Hosokawa Micron Corporation), Hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, Kawasaki Heavy Industries Ltd.) Company-made).

Hereinafter, each component constituting the toner will be described.
(A) Binder Resin The first and second binder resins used in the toner of the present invention are polar, and for example, those having an acid value of 5 mgKOH / g or more are preferable. As described above, since the first and second binder resins have an acid value of 5 mgKOH / g or more, the occurrence of filming can be more reliably suppressed, the fixing property and the transfer efficiency can be improved, and high-quality images can be obtained. Can be obtained.

  The kind of the binder resin is not particularly limited, and a binder resin for black toner or color toner can be used. For example, polyester resin, polystyrene and styrene-acrylate copolymer resin, etc. Styrene resin, acrylic resin such as polymethyl methacrylate, polyolefin resin such as polyethylene, polyurethane resin, epoxy resin and the like. Moreover, you may use resin obtained by mixing the mold release agent corresponding to a raw material monomer mixture, and making it polymerize. Binder resin can be used individually by 1 type, or can use 2 or more types together.

  Among the above, the first and second binder resins preferably contain a polyester resin. A polyester resin is superior in durability and transparency as compared with other resins such as an acrylic resin, and has a low softening point (Tm). Therefore, a toner excellent in durability and color developability can be obtained by containing a polyester resin as a binder resin. Further, it is possible to obtain a toner having excellent low-temperature fixability that can be fixed at a lower temperature.

  The polyester resin can be synthesized by a condensation polymerization reaction. For example, it can be synthesized by polycondensation reaction, specifically dehydration condensation reaction of polybasic acids and polyhydric alcohols in the presence of a catalyst in an organic solvent or without solvent. At this time, a demethanol polycondensation reaction may be carried out using a methyl esterified product of a polybasic acid as part of the polybasic acid. The polycondensation reaction between the polybasic acid and the polyhydric alcohol may be terminated when the acid value and softening temperature of the polyester resin to be produced reach the values in the polyester resin to be synthesized. In this polycondensation reaction, by appropriately changing the reaction conditions such as the blending ratio of polybasic acids and polyhydric alcohols and the reaction rate, for example, the content of carboxyl groups bonded to the terminal of the resulting polyester resin, and thus The acid value of the obtained polyester resin can be easily adjusted, and thereby the physical properties such as the softening temperature can be easily adjusted. Therefore, by containing a polyester resin as the binder resin, it is possible to more easily suppress the occurrence of filming, improve the fixing property and transfer efficiency, and obtain a high-quality image.

  The glass transition point (Tg) of the binder resin is not particularly limited and can be appropriately selected from a wide range, but it is preferably 30 ° C. or higher and 80 ° C. or lower in consideration of the fixing property and storage stability of the obtained toner. . When the temperature is less than 30 ° C., the storage stability becomes insufficient, so that the toner is likely to thermally aggregate inside the image forming apparatus, which may cause development failure. Further, the temperature at which the high temperature offset phenomenon starts to occur is lowered. “High temperature offset phenomenon” means that when toner is fixed on a recording medium by heating and pressurizing with a fixing member such as a fixing roller, the cohesive force of toner particles adheres to the toner and the fixing member due to overheating of the toner. This is a phenomenon in which the toner layer is divided below the force and a part of the toner adheres to the fixing member and is removed. On the other hand, when the temperature exceeds 80 ° C., the fixing property is deteriorated, so that fixing failure may occur.

  The softening point (Tm) of the binder resin is not particularly limited and can be appropriately selected from a wide range, but is preferably 150 ° C. or lower, and more preferably 80 ° C. or higher and 150 ° C. or lower. If the temperature is less than 80 ° C., the storage stability of the toner is reduced, and the toner is likely to thermally aggregate inside the image forming apparatus, and the toner cannot be stably supplied to the latent image carrier, resulting in poor development. May occur. In addition, a failure of the image forming apparatus may be induced. If the temperature exceeds 150 ° C., the binder resin is difficult to melt in the first and second melt-kneading steps, so that it becomes difficult to melt and knead the toner raw material, and the colorant, release agent and charge control in the melt-kneaded product are difficult. The dispersibility of the agent may decrease. Further, when the toner is fixed on the recording medium, the toner is hardly melted or softened, so that the fixing property of the toner to the recording medium is lowered, and there is a possibility that a fixing defect occurs.

  The softening point of the first binder resin is preferably higher than the softening point of the second binder resin. The difference between the softening point of the first binder resin and the softening point of the second binder resin is preferably 5 ° C. or higher and 30 ° C. or lower. As a result, the dispersibility of the first release agent in the first toner particle group is further lowered, so that the release agent can be more easily oozed out during fixing, and the fixing property, particularly the low temperature fixing property is improved. Can be. Further, since the dispersibility of the second release agent in the second binder resin is further improved, the occurrence of filming can be further suppressed, and the adhesion force of the toner to the photoreceptor can be further reduced. Therefore, the transfer efficiency can be improved. Therefore, the occurrence of filming can be further suppressed, the fixability and the transfer efficiency can be further improved, and a higher quality image can be obtained.

  As the first and second binder resins, the same type may be used, or different types may be used.

(B) Colorant Examples of the colorant include a yellow toner colorant, a magenta toner colorant, a cyan toner colorant, and a black toner colorant.

  Examples of the colorant for yellow toner include C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 5, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 15 and C.I. I. Azo pigments such as CI Pigment Yellow 17, inorganic pigments such as yellow iron oxide and ocher; I. Nitro dyes such as Acid Yellow 1, C.I. I. Solvent Yellow 2, C.I. I. Solvent Yellow 6, C.I. I. Solvent Yellow 14, C.I. I. Solvent Yellow 15, C.I. I. Solvent Yellow 19, and C.I. I. Examples thereof include oil-soluble dyes such as Solvent Yellow 21.

  Examples of the colorant for magenta toner include C.I. I. Pigment red 49, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 57, C.I. I. Pigment red 81, C.I. I. Pigment red 122, C.I. I. Solvent Red 19, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Basic Red 10 and C.I. I. Disperse Red 15 etc. are mentioned.

  Examples of the colorant for cyan toner include C.I. I. Pigment blue 15, C.I. I. Pigment blue 16, C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 70, C.I. I. Direct Blue 25, and C.I. I. Direct Blue 86 and the like can be mentioned.

  Examples of the colorant for black toner include carbon black such as channel black, roller black, disk black, gas furnace black, oil furnace black, thermal black, and acetylene black. From these various types of carbon black, an appropriate carbon black may be appropriately selected according to the design characteristics of the toner to be obtained.

  In addition to these pigments, red pigments and green pigments can be used. A coloring agent can be used individually by 1 type, or can use 2 or more types together. Two or more of the same color can be used, and one or more of the different colors can also be used.

  The colorant is preferably used as a masterbatch. A master batch of a colorant can be produced, for example, by kneading a synthetic resin melt and a colorant. As the synthetic resin, the same kind of resin as the toner binder resin or a resin having good compatibility with the toner binder resin is used. The proportion of the colorant used in the masterbatch is not particularly limited, but is preferably 30 to 100 parts by weight with respect to 100 parts by weight of the synthetic resin, that is, 23 to 50% by weight with respect to 100% by weight of the masterbatch. It is as follows. The master batch is used after being granulated to a particle size of, for example, about 2 mm to 3 mm.

  Although the content of the colorant in the toner of the present invention is not particularly limited, it is 4 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the binder resin in each of the first toner particle group and the second toner particle group. Preferably there is. When using a masterbatch, it is preferable to adjust the usage amount of the masterbatch so that the content of the colorant in the toner of the present invention falls within the above range. By using the colorant in the above range, it is possible to form a good image having a sufficient image density, high color developability and excellent image quality.

  As the first and second colorants, the same type or different types may be used, but it is preferable to use the same type.

(C) Release agent By containing a release agent, the effect of preventing offset can be enhanced. The first release agent used in the toner of the present invention preferably has an acid value of less than 3 mgKOH / g, and the second release agent preferably has an acid value of 3 mgKOH / g or more. Thereby, the occurrence of filming can be suppressed more reliably, the fixing property and the transfer efficiency can be improved, and a high-quality image can be obtained.

  The types of release agents include, for example, paraffin wax and derivatives thereof, and petroleum wax such as microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, low molecular polypropylene wax and derivatives thereof, And hydrocarbon synthetic waxes such as polyolefin polymer wax and derivatives thereof, carnauba wax and derivatives thereof, rice wax and derivatives thereof, candelilla wax and derivatives thereof, plant waxes such as wood wax, animals such as beeswax and whale wax Oils, synthetic waxes such as fatty acid amides, phenol fatty acid esters, long chain carboxylic acids and derivatives thereof, long chain alcohols and derivatives thereof, silicone polymerization , Such as higher fatty acid, and the like. Derivatives include oxides, block copolymers of vinyl monomers and waxes, and copolymers of vinyl monomers and waxes.

  The mixing amount of the first release agent is not particularly limited and can be appropriately selected from a wide range, but is preferably 4.0% by weight or more with respect to the first mixture. The mixing amount of the second release agent is not particularly limited and can be appropriately selected from a wide range, but is preferably 4.0% by weight or more with respect to the second mixture. As described above, by adjusting the mixing amount of the release agent in the first and second premixing steps within the above range, the effect of suppressing the occurrence of filming and the effect of improving the fixing property and the transfer efficiency are balanced. It is possible to adjust, and a higher quality image can be obtained. If the mixing amount of the release agent is less than 4.0% by weight, the function of the release agent may not be sufficiently obtained.

  The melting point of the first release agent is preferably 70 ° C. or lower. As a result, it is possible to obtain a toner having better low-temperature fixability. If the melting point of the first release agent exceeds 70 ° C., the release agent cannot be sufficiently eluted when fixing the toner to the recording medium, and the effect of improving the high temperature offset resistance may not be sufficiently exhibited. There is.

  The melting point of the second release agent is preferably 50 ° C. or higher and 150 ° C. or lower, and more preferably 120 ° C. or lower. If the melting point is less than 50 ° C., the release agent may melt in the developing device, causing toner particles to aggregate, and causing defects such as filming on the photoreceptor. If the melting point exceeds 150 ° C., the release agent cannot be sufficiently eluted when the toner is fixed on the recording medium, and the effect of improving the high temperature offset resistance may not be sufficiently exhibited.

Here, the melting point of the release agent is the differential scanning calorimetry (Differential Scanning Calorimetry).
: The temperature at the top of the endothermic peak corresponding to the melting of the DSC curve obtained by the abbreviation DSC).

(D) Charge control agent The toner may contain other toner additive components such as a charge control agent in addition to the binder resin, the colorant, and the release agent. The charge control agent is internally added to bring the toner triboelectric charge amount into a suitable range. As the charge control agent, a charge control agent for positive charge control or negative charge control can be used. Examples of the charge control agent for controlling positive charge include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, and triphenylmethane. Examples thereof include derivatives, guanidine salts, and amidine salts. Examples of the charge control agent for controlling the negative charge include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, naphthenic acid metal salts, metal complexes and metal salts of salicylic acid and its derivatives ( Examples of the metal include chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, and resin acid soaps. One charge control agent can be used alone, or two or more charge control agents can be used in combination.

  The content of the charge control agent in the toner of the present invention is not particularly limited, but in each of the first toner particle group and the second toner particle group, 0.5 part by weight or more and 5 parts by weight with respect to 100 parts by weight of the binder resin. The amount is preferably 0.5 parts by weight or less, and more preferably 0.5 parts by weight or more and 3 parts by weight or less. By setting the mixing amount of the charge control agent within the above range, the charge amount of the toner can be easily adjusted to an optimal value, and the charging characteristics can be easily stabilized. When the mixing amount of the charge control agent exceeds 5 parts by weight, the carrier is contaminated and toner scattering may occur. If the amount is less than 0.5 part by weight, there is a possibility that sufficient charging characteristics cannot be imparted to the toner.

[First and second melt-kneading steps]
In the first melt-kneading process of step S2 and the second melt-kneading process of step S6, the first mixture produced in the first premixing process of step S1 and the second premixing process of step S5 and The second mixture is melt-kneaded to produce a first melt-kneaded product and a second melt-kneaded product. The melt kneading is performed by heating to a temperature not lower than the softening point of the binder resin and lower than the thermal decomposition temperature. As a result, the binder resin is melted or softened, and toner raw materials other than the binder resin such as a colorant, a release agent, and a charge control agent can be dispersed in the binder resin. The specific heating temperature during melt kneading is preferably, for example, 80 ° C. or higher and 200 ° C. or lower, and more preferably 100 ° C. or higher and 150 ° C. or lower.

  For melt-kneading, kneaders such as a kneader, a twin-screw extruder, a two-roll mill, a three-roll mill, and a lab blast mill can be used. As such a kneader, for example, TEM-100B (trade name, Uniaxial or biaxial extruder such as Toshiba Machine Co., Ltd., PCM-65, PCM-65 / 87, PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.), Needex (trade name, Mitsui Mining Co., Ltd.) Open roll type kneaders, etc.). Further, melt kneading may be performed using a plurality of kneaders.

[First and second grinding steps]
In the first pulverization step in step S3 and the second pulverization step in step S7, the first melt-kneaded materials produced in the first melt-kneading step in step S2 and the second melt-kneading step in step S6, respectively. The second melt-kneaded product is solidified and then pulverized to produce a first pulverized product and a second pulverized product. The first melt-kneaded product and the second melt-kneaded product are first solidified by, for example, cooling, and then first first coarsely having a volume average particle size of, for example, about 100 μm to 5 mm by a hammer mill or a cutter mill. The pulverized product and the second coarsely pulverized product are respectively pulverized. Thereafter, the obtained first coarsely pulverized product and second coarsely pulverized product are pulverized to a first pulverized product and a second pulverized product having a desired volume average particle diameter, respectively. For pulverization of the first coarsely pulverized product and the second coarsely pulverized product, for example, a jet type pulverizer using a supersonic jet stream or a rotor (rotor) and a stator (liner) that rotate at high speed are used. An impact type pulverizer that introduces and pulverizes the above coarsely pulverized product into the space formed between the above and the like.

[First and second classification steps]
In the first classification step in step S4 and the second classification step in step S8, the first pulverized product and the second pulverized product produced in the first pulverization step in step S3 and the second pulverization step in step S7, respectively. Each of the pulverized products is classified to produce a first toner particle group and a second toner particle group having a volume average particle size smaller than that of the first toner particle group.

  As a classifier that performs classification, a known classifier can be used, and examples thereof include a swirling wind classifier (rotary wind classifier).

  The first classification step is preferably performed such that the volume average particle size of the first toner particle group obtained after classification is 4 μm or more and 7 μm or less by appropriately adjusting the classification conditions. If the volume average particle size of the first toner particle group is less than 4 μm, the content of small particle size particles having a volume average particle size of 2 μm or less in the toner is excessively increased, and there is a risk of in-machine contamination due to toner scattering. is there. On the other hand, if it exceeds 7 μm, there is a possibility that a high-definition and high-resolution image cannot be obtained.

  The second classification step is preferably performed so that the classification condition is appropriately adjusted so that the volume average particle size of the second toner particle group obtained after the classification is 3 μm or more and 5 μm or less. If the volume average particle size of the second toner particle group is less than 3 μm, the content of small particle size particles in the toner becomes too large, and there is a risk of in-machine contamination due to toner scattering. On the other hand, if it exceeds 7 μm, there is a possibility that a high-definition and high-resolution image cannot be obtained.

  When the volume average particle size of the first and second toner particle groups satisfies the above range, the range of the particle size distribution of the toner obtained after the mixing step is 4 μm or more and 7 μm or less. A high-resolution image with resolution can be obtained.

  Further, the coefficient of variation (CV value) of the particle size distribution of the second toner particle group is preferably 30% or less. When the variation coefficient of the particle size distribution of the second toner particle group satisfies the above range, the amount of small particle size particles having a volume average particle size of 2 μm or less is limited. It is possible to prevent image quality degradation that occurs. If the variation coefficient of the particle size distribution of the second toner particle group exceeds 30%, the amount of the small particle size becomes excessive, which may cause toner scattering due to fluidity deterioration and image quality deterioration due to transfer efficiency deterioration. There is.

  The classification condition to be adjusted is, for example, the rotational speed of the classification rotor in a swirl type wind classifier (rotary type wind classifier).

In the present specification, the volume average particle diameter and the coefficient of variation (CV value) are values measured by a particle size distribution measuring device “Multisizer 3” manufactured by Beckman Coulter, Inc. In the present specification, the volume average particle diameter indicates a particle diameter D _{50V at} which the cumulative volume from the large particle diameter side in the cumulative volume distribution becomes 50%. The measurement conditions of the volume average particle diameter (D _50V ) and the coefficient of variation (CV value) are shown below.
Aperture diameter: 100 μm
Measurement particle number: 50000 count Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter, Inc.)
Electrolyte: ISOTON-II (Beckman Coulter, Inc.)
Dispersant: Sodium alkyl ether sulfate Measurement method: Add 50 ml of electrolyte, 20 mg of sample, and 1 ml of dispersant to a beaker, and use ultrasonic disperser (trade name: UH-50, manufactured by SMT Corporation) at an ultrasonic frequency of 20 kHz. The sample for measurement is prepared by dispersion treatment for 3 minutes, the particle size is measured by the apparatus “Multisizer 3”, the volume particle size distribution of the sample particles is obtained from the obtained measurement result, and the volume average particle size is obtained from the obtained volume particle size distribution. The diameter (D _50V ) is calculated. Moreover, the standard deviation in volume particle size distribution is calculated | required, and a coefficient of variation (CV value,%) is calculated based on following formula (1). The coefficient of variation means that the smaller the value, the narrower the particle size distribution width.
CV value (%) = {standard deviation in volume particle size distribution / volume average particle size (μm)} × 100
... (1)

[Mixing process]
In the mixing step of Step S9, the first toner particle group and the second toner particle group produced in the first classification step of Step S4 and the second classification step of Step S8 are mixed, and thereby the present invention. Toner is manufactured.

  A known mixer can be used for mixing. For example, Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), mechano mill (trade name) Henschel-type mixing equipment such as Okada Seiko Co., Ltd., Ongmill (trade name, manufactured by Hosokawa Micron Corporation), Hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, Kawasaki Heavy Industries Ltd.) Company-made).

  In the mixing step, it is preferable to mix the first toner particle group and the second toner particle group so that the content of the second toner particle group is 2 wt% or more and 20 wt% or less.

  As a result, the content of fine powder in the toner can be controlled within a more suitable range, so that deterioration in image quality caused by poor fluidity and transfer efficiency can be prevented more reliably, and high definition and high resolution can be achieved. A toner capable of forming a quality image can be manufactured. If the content of the second toner particle group is less than 2% by weight, the content of fine powder becomes insufficient, so that a high-quality image with sufficiently high definition and high resolution may not be obtained. . On the other hand, if the content exceeds 20% by weight, the content of fine powder is excessively increased, so that the fluidity is lowered and the image quality may be deteriorated due to poor transfer efficiency.

  The toner manufactured as described above has an external additive that has functions such as powder flowability improvement, triboelectric chargeability improvement, heat resistance improvement, long-term storage stability improvement, cleaning property improvement and photoreceptor surface wear property control. May be mixed. Examples of the external additive include silica fine powder, titanium oxide fine powder, and alumina fine powder. External additives can be used alone or in combination of two or more. The external additive is added in an amount of 0.1 to 100 parts by weight of the toner in consideration of the charge amount necessary for the toner, the influence of the external additive on the abrasion of the photoreceptor, the environmental characteristics of the toner, and the like. 1 to 10 parts by weight is preferable, and 0.1 to 2 parts by weight is more preferable. The external additive may be added to each particle group before mixing the first toner particle group and the second toner particle group in the mixing step.

  When the mixing process is completed, the process proceeds from step S9 to step S10, and the production of the toner of the present invention is completed.

  By manufacturing the toner of the present invention using the toner manufacturing method as described above, the toner of the present invention can suppress filming, improve the fixing property and transfer efficiency, and obtain a high-quality image. Can be manufactured.

  The toner of the present invention thus produced can be used as it is as a one-component developer, or can be mixed with a carrier and used as a two-component developer.

  As the carrier, magnetic particles can be used. Specific examples of the particles having magnetism include metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum or lead. Among these, ferrite is preferable.

  Alternatively, a resin-coated carrier in which magnetic particles are coated with a resin, or a resin-dispersed carrier in which magnetic particles are dispersed in a resin may be used as the carrier. Although it does not restrict | limit especially as resin which coat | covers the particle | grains which have magnetism, For example, an olefin resin, a styrene resin, a styrene acrylic resin, a silicone resin, ester resin, a fluorine-containing polymer system resin etc. are mentioned. Moreover, although it does not restrict | limit especially as resin used for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester-type resin, a fluorine resin, a phenol resin etc. are mentioned.

The shape of the carrier is preferably a spherical shape or a flat shape. The volume average particle diameter of the carrier is not particularly limited, but is preferably 10 μm to 100 μm, more preferably 20 μm to 50 μm, considering high image quality. Furthermore, the resistivity of the carrier is preferably 10 ⁸ Ω · cm or more, more preferably 10 ¹² Ω · cm or more. The carrier resistivity is determined by placing the carrier in a container having a cross-sectional area of 0.50 cm ² and tapping it, then applying a load of 1 kg / cm ² to the particles packed in the container and placing the load between the load and the bottom electrode. This is a value obtained by reading a current value when a voltage generating an electric field of 1000 V / cm is applied. When the resistivity is low, charges are injected into the carrier when a bias voltage is applied to the developing sleeve (developing roller), and carrier particles are likely to adhere to the photoreceptor. Further, breakdown of the bias voltage is likely to occur.

  The magnetization strength (maximum magnetization) of the carrier is preferably 10 emu / g to 60 emu / g, more preferably 15 emu / g to 40 emu / g. The magnetization strength depends on the magnetic flux density of the developing roller, but under the general magnetic flux density conditions of the developing roller, if it is less than 10 emu / g, the magnetic binding force does not work and causes carrier scattering. There is a fear. On the other hand, if the magnetization strength exceeds 60 emu / g, it is difficult to maintain a non-contact state with the photosensitive member as the latent image carrier in the non-contact development in which the spike of the carrier becomes too high. Further, in the contact development, there is a risk that a sweep is likely to appear in the toner image.

The use ratio of the toner and the carrier in the two-component developer is not particularly limited and can be appropriately selected according to the type of the toner and the carrier. However, the toner is used so that the carrier coverage with the toner is 40% or more and 80% or less. Use it. The resin-coated ^carrier: Taking an example (density of ^{5g / cm 2 ~8g / cm 2} ), the two-component in the developer, the toner is 30 wt% 2 wt% or more of the two-component developer total amount or less, preferably The toner may be used so that it is contained in an amount of 2 wt% or more and 20 wt% or less.

  The two-component developer of the present invention contains the toner of the present invention capable of suppressing the occurrence of filming, improving the fixability and transfer efficiency, and obtaining a high-quality image, and the carrier. Since thermal aggregation of the developer can be suppressed and the toner can be stably supplied to the latent image carrier, a high-quality image can be stably obtained over a long period of time.

[Image forming apparatus]
FIG. 2 is a diagram schematically showing an example of the configuration of the image forming apparatus 100 suitable for using the toner of the present invention. The image forming apparatus 100 is a multifunction device having both a copying function, a printer function, and a facsimile function, and forms a full-color or monochrome image on a recording medium in accordance with transmitted image information. That is, the image forming apparatus has three types of printing modes, ie, a copier mode (copying mode), a printer mode, and a FAX mode. Operation input from an operation unit (not shown), personal computer, portable terminal device, information recording A print mode is selected by a control unit (not shown) in response to reception of a print job from an external device using a storage medium or a memory device. The image forming apparatus 100 includes a toner image forming unit 20, a transfer unit 30, a fixing unit 40, a recording medium supply unit 50, and a discharge unit 60. Each member constituting the toner image forming unit 20 and some members included in the transfer unit 30 are black (b), cyan (c), magenta (m), and yellow (y) colors included in the color image information. In order to correspond to the image information, four each are provided. Here, each member provided by four according to each color is distinguished by attaching an alphabet representing each color to the end of the reference symbol, and when referring collectively, only the reference symbol is used.

  The toner image forming unit 20 includes a photosensitive drum 21, a charging unit 22, an exposure unit 23, a developing device 24, and a cleaning unit 25. The charging unit 22, the developing device 24, and the cleaning unit 25 are arranged around the photosensitive drum 21 in this order. The charging unit 22 is disposed below the developing device 24 and the cleaning unit 25 in the vertical direction.

  The photosensitive drum 21 is supported by a driving unit (not shown) so as to be rotatable around an axis, and is a latent image carrier including a conductive substrate (not shown) and a photosensitive layer formed on the surface of the conductive substrate. . The conductive substrate can take various shapes, and examples thereof include a cylindrical shape, a columnar shape, and a thin film sheet shape. Among these, a cylindrical shape is preferable. The conductive substrate is formed of a conductive material. As the conductive material, those commonly used in this field can be used. For example, metals such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, platinum, etc. A conductive layer made of one or more of aluminum, aluminum alloy, tin oxide, gold, indium oxide and the like is formed on a film-like substrate such as two or more alloys, synthetic resin film, metal film, paper, etc. And a resin composition containing at least one of conductive particles or a conductive polymer. In addition, as a film-form base | substrate used for an electroconductive film, a synthetic resin film is preferable and a polyester film is especially preferable. Moreover, as a formation method of the electroconductive layer in an electroconductive film, vapor deposition, application | coating, etc. are preferable.

  The photosensitive layer is formed, for example, by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. In that case, it is preferable to provide an undercoat layer between the conductive substrate and the charge generation layer or the charge transport layer. By providing an undercoat layer, the surface of the conductive substrate is covered with scratches and irregularities, and the surface of the photosensitive layer is smoothed. Prevents deterioration of the chargeability of the photosensitive layer during repeated use, at least in a low-temperature environment. The advantage of improving the charging characteristics of the photosensitive layer in either a low or low humidity environment is obtained. Further, it may be a laminated photosensitive layer having a three-layer structure excellent in durability in which a protective layer for protecting the surface of the photosensitive layer is provided on the uppermost layer.

  The charge generation layer is mainly composed of a charge generation material that generates a charge when irradiated with light, and contains a known binder resin, plasticizer, sensitizer and the like as necessary. As the charge generation material, those commonly used in this field can be used. Phthalocyanine pigments such as metal-free phthalocyanine, squalium dye, azulenium dye, thiapyrylium dye, carbazole skeleton, styryl stilbene skeleton, triphenylamine skeleton, dibenzothiophene skeleton, oxadiazole skeleton, fluorenone skeleton, bis stilbene skeleton, distyryl oxa And azo pigments having a diazole skeleton or a distyrylcarbazole skeleton. Among these, metal-free phthalocyanine pigments, oxotitanyl phthalocyanine pigments, bisazo pigments containing at least either a fluorene ring or a fluorenone ring, bisazo pigments composed of aromatic amines, trisazo pigments, etc. have high charge generation ability, Suitable for obtaining a sensitive photosensitive layer. One type of charge generating material can be used alone, or two or more types can be used in combination. The content of the charge generation material is not particularly limited, but is preferably 5 parts by weight to 500 parts by weight, more preferably 10 parts by weight to 200 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer. As the binder resin for the charge generation layer, those commonly used in this field can be used. For example, melamine resin, epoxy resin, silicone resin, polyurethane, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate, phenoxy resin , Polyvinyl butyral, polyarylate, polyamide, polyester and the like. Binder resin can be used individually by 1 type, or can use 2 or more types together as needed.

  The charge generation layer generates charge by dissolving or dispersing appropriate amounts of charge generation materials, binder resins and, if necessary, plasticizers and sensitizers in an appropriate organic solvent capable of dissolving or dispersing these components. It can be formed by preparing a layer coating solution, applying this charge generation layer coating solution to the surface of the conductive substrate and drying. The film thickness of the charge generation layer thus obtained is not particularly limited, but is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2.5 μm.

  The charge transport layer laminated on the charge generation layer has a charge transport material having the ability to accept and transport the charge generated from the charge generation material and a binder resin for the charge transport layer as essential components. Contains known antioxidants, plasticizers, sensitizers, lubricants and the like. As the charge transport material, those commonly used in this field can be used, for example, poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, Polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, pyrazoline Derivatives, phenylhydrazones, hydrazone derivatives, triphenylamine compounds, tetraphenyldiamine compounds, triphenylmethane compounds, stilbene compounds, 3-methyl-2-benzothiazoli Electron donating substances such as azine compounds having a ring, fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetra And electron accepting substances such as cyanoethylene, tetracyanoquinodimethane, promanyl, chloranil, and benzoquinone. The charge transport materials can be used alone or in combination of two or more. The content of the charge transport material is not particularly limited, but is preferably 10 to 300 parts by weight, more preferably 30 to 150 parts by weight, with respect to 100 parts by weight of the binder resin in the charge transport layer. As the binder resin for the charge transport layer, those commonly used in this field and capable of uniformly dispersing the charge transport material can be used. For example, polycarbonate, polyarylate, polyvinyl butyral, polyamide, polyester, polyketone, epoxy resin, polyurethane , Polyvinyl ketone, polystyrene, polyacrylamide, phenol resin, phenoxy resin, polysulfone resin, and copolymer resins thereof. Among these, in consideration of film formability, wear resistance of the resulting charge transport layer, electrical characteristics, etc., polycarbonate containing bisphenol Z as a monomer component (hereinafter referred to as “bisphenol Z type polycarbonate”), bisphenol Z type polycarbonate And a mixture of polycarbonate with other polycarbonates are preferred. Binder resin can be used individually by 1 type, or can use 2 or more types together.

  The charge transport layer preferably contains an antioxidant together with the charge transport material and the binder resin for the charge transport layer. As the antioxidant, those commonly used in this field can be used, and examples thereof include vitamin E, hydroquinone, hindered amine, hindered phenol, paraphenylenediamine, arylalkane and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. It is done. One antioxidant can be used alone, or two or more antioxidants can be used in combination. The content of the antioxidant is not particularly limited, but is 0.01% to 10% by weight, preferably 0.05% to 5% by weight, based on the total amount of components constituting the charge transport layer. The charge transport layer is dissolved or dispersed in a suitable organic solvent that can dissolve or disperse these components in an appropriate amount such as a charge transport material and a binder resin, and if necessary, an antioxidant, a plasticizer, and a sensitizer. The charge transport layer coating liquid is prepared, and the charge transport layer coating liquid is applied to the surface of the charge generation layer and dried. The thickness of the charge generation layer thus obtained is not particularly limited, but is preferably 10 μm to 50 μm, more preferably 15 μm to 40 μm. Note that a photosensitive layer in which a charge generation material and a charge transport material are present can be formed in one layer. In that case, the type, content, binder resin, and other additives of the charge generation material and the charge transport material may be the same as in the case of separately forming the charge generation layer and the charge transport layer.

  In this embodiment, the photosensitive drum formed by forming the organic photosensitive layer using the charge generation material and the charge transport material as described above is used. Instead, an inorganic photosensitive layer using silicon or the like is formed. Can be used.

  The charging means 22 faces the photosensitive drum 21 and is arranged so as to be separated from the surface of the photosensitive drum 21 along the longitudinal direction of the photosensitive drum 21 with a gap, and the surface of the photosensitive drum 21 has a predetermined polarity and Charge to potential. As the charging means 22, a charging brush type charger, a charger type charger, a sawtooth type charger, an ion generator, or the like can be used. In the present embodiment, the charging unit 22 is provided so as to be separated from the surface of the photosensitive drum 21, but is not limited thereto. For example, a charging roller may be used as the charging unit 22 and the charging roller may be disposed so that the charging roller and the photosensitive drum 21 are in pressure contact with each other, or a contact charging type charger such as a charging brush or a magnetic brush may be used. Also good.

  The exposure unit 23 is arranged so that light of each color information emitted from the exposure unit 23 passes between the charging unit 22 and the developing device 24 and is irradiated on the surface of the photosensitive drum 21. The exposure unit 23 branches the image information into light of each color information of black (b), cyan (c), magenta (m), and yellow (y) in the unit, and is charged to a uniform potential by the charging unit 22. The surface of the photosensitive drum 21 thus exposed is exposed with light of each color information, and an electrostatic latent image is formed on the surface. As the exposure unit 23, for example, a laser scanning unit including a laser irradiation unit and a plurality of reflection mirrors can be used. In addition, a unit in which an LED array, a liquid crystal shutter, and a light source are appropriately combined may be used.

  FIG. 3 is a diagram schematically showing an example of the configuration of the developing device 24 suitable for using the toner of the present invention. The developing device 24 includes a developing tank 26 and a toner hopper 27. The developing tank 26 is disposed so as to face the surface of the photosensitive drum 21, and supplies and develops toner on the electrostatic latent image formed on the surface of the photosensitive drum 21 to form a visible toner image. It is a shaped member. The developing tank 26 accommodates toner in its internal space and accommodates a roller member such as a developing roller 26a, a supply roller 26b, and a stirring roller 26c, or a screw member, and rotatably supports it. An opening is formed in a side surface of the developing tank 26 facing the photosensitive drum 21, and a developing roller 26 a is rotatably provided at a position facing the photosensitive drum 21 through the opening. The developing roller 26 a is a roller-like member that supplies toner to the electrostatic latent image on the surface of the photosensitive drum 21 at the pressure contact portion or the closest portion with the photosensitive drum 21. When supplying the toner, a potential having a polarity opposite to the charging potential of the toner is applied to the surface of the developing roller 26a as a developing bias voltage (hereinafter simply referred to as “developing bias”). As a result, the toner on the surface of the developing roller 26a is smoothly supplied to the electrostatic latent image. Further, by changing the developing bias value, the amount of toner (toner adhesion amount) supplied to the electrostatic latent image can be controlled. The supply roller 26b is a roller-like member provided so as to be able to rotate and face the developing roller 26a, and supplies toner around the developing roller 26a. The agitating roller 26c is a roller-like member provided so as to be rotatable and facing the supply roller 26b, and feeds toner newly supplied from the toner hopper 27 into the developing tank 26 to the periphery of the supply roller 26b. The toner hopper 27 is provided so that a toner replenishing port (not shown) provided at the lower part in the vertical direction communicates with a toner receiving port (not shown) provided at the upper part in the vertical direction of the developing tank 26. The toner is replenished according to the 26 toner consumption status. Further, the toner hopper 27 may not be used, and the toner may be directly supplied from each color toner cartridge.

  After the toner image is transferred to the recording medium, the cleaning unit 25 removes the toner remaining on the surface of the photosensitive drum 21 and cleans the surface of the photosensitive drum 21. For the cleaning unit 25, for example, a plate-like member such as a cleaning blade is used. In the image forming apparatus of the present invention, an organic photosensitive drum is mainly used as the photosensitive drum 21, and the surface of the organic photosensitive drum is mainly composed of a resin component. Surface degradation is likely to proceed due to the chemical action of ozone generated by the discharge. However, the deteriorated surface portion is worn by receiving a rubbing action by the cleaning unit 25 and is gradually but surely removed. Therefore, the problem of surface deterioration due to ozone or the like is practically solved, and the charging potential by the charging operation can be stably maintained over a long period of time. Although the cleaning unit 25 is provided in the present embodiment, the present invention is not limited to this, and the cleaning unit 25 may not be provided.

  According to the toner image forming unit 20, an electrostatic latent image is formed by irradiating the surface of the photosensitive drum 21 that is uniformly charged by the charging unit 22 with signal light corresponding to the image information from the exposure unit 23. Toner is supplied from the developing device 24 to form a toner image, and the toner image is transferred to the intermediate transfer belt 28, and then the toner remaining on the surface of the photosensitive drum 21 is removed by the cleaning unit 25. This series of toner image forming operations is repeatedly executed.

The transfer means 30 is disposed above the photosensitive drum 21, and includes an intermediate transfer belt 28, a driving roller 29, a driven roller 31, intermediate transfer rollers 32b, 32c, 32m, and 32y, a transfer belt cleaning unit 33, and a transfer belt. A roller 34. The intermediate transfer belt 28 is an endless belt-like member that is stretched by a driving roller 29 and a driven roller 31 to form a loop-shaped movement path. The direction of the arrow B, that is, the surface in contact with the photosensitive drum 21 is photosensitive. It is rotationally driven so as to move in the direction from the body drum 21y to 21b.
When the intermediate transfer belt 28 passes through the photosensitive drum 21 while being in contact with the photosensitive drum 21, an intermediate transfer roller 32 disposed opposite to the photosensitive drum 21 via the intermediate transfer belt 28 causes the surface of the photosensitive drum 21. A transfer bias having a polarity opposite to the charging polarity of the toner is applied, and the toner image formed on the surface of the photosensitive drum 21 is transferred onto the intermediate transfer belt 28. In the case of a full-color image, the toner images of the respective colors formed on the respective photoconductive drums 21y, 21m, 21c, and 21b are sequentially transferred onto the intermediate transfer belt 28, thereby forming a full-color toner image. The driving roller 29 is provided so as to be rotatable around its axis by a driving means (not shown), and the intermediate transfer belt 28 is rotationally driven in the direction of the arrow B by the rotational driving. The driven roller 31 is provided so as to be able to be driven and rotated by the rotational drive of the driving roller 29, and applies a certain tension to the intermediate transfer belt 28 so that the intermediate transfer belt 28 does not loosen. The intermediate transfer roller 32 is provided in pressure contact with the photosensitive drum 21 via the intermediate transfer belt 28, and can be driven to rotate about its axis by a driving unit (not shown). The intermediate transfer roller 32 is connected to a power source (not shown) for applying a transfer bias as described above, and has a function of transferring the toner image on the surface of the photosensitive drum 21 to the intermediate transfer belt 28. The transfer belt cleaning unit 33 is provided so as to face the driven roller 31 through the intermediate transfer belt 28 and to contact the outer peripheral surface of the intermediate transfer belt 28. The toner that adheres to the intermediate transfer belt 28 by contact with the photosensitive drum 21 and remains without being transferred to the recording medium causes contamination of the back surface of the recording medium. Residual toner on the surface is removed and collected. The transfer roller 34 is provided in pressure contact with the drive roller 29 via the intermediate transfer belt 28, and can be driven to rotate about an axis by a drive unit (not shown). At the pressure contact portion (transfer nip portion) between the transfer roller 34 and the drive roller 29, a toner image carried and conveyed by the intermediate transfer belt 28 is transferred to a recording medium fed from a recording medium supply means 50 described later. Is done. The recording medium carrying the toner image is fed to the fixing unit 40. According to the transfer unit 30, the toner image transferred from the photosensitive drum 21 to the intermediate transfer belt 28 at the pressure contact portion between the photosensitive drum 21 and the intermediate transfer belt 28 rotates the intermediate transfer belt 28 in the arrow B direction. It is conveyed to a transfer nip portion by driving, and transferred to a recording medium there.

  The fixing unit 40 is provided downstream of the transfer unit 30 in the conveyance direction of the recording medium, and includes a fixing roller 35 and a pressure roller 36. The fixing roller 35 is rotatably provided by a driving unit (not shown), and heats and melts the toner constituting the unfixed toner image carried on the recording medium to fix it on the recording medium. A heating unit (not shown) is provided inside the fixing roller 35. The heating unit heats the fixing roller 35 so that the surface of the fixing roller 35 reaches a predetermined temperature (heating temperature). For example, a heater or a halogen lamp can be used as the heating means. The heating means is controlled by fixing condition control means described later. A temperature detection sensor is provided near the surface of the fixing roller 35 to detect the surface temperature of the fixing roller 35. The detection result by the temperature detection sensor is written in the storage unit of the control means described later. The fixing condition control unit controls the operation of the heating unit based on the detection result written in the storage unit. The pressure roller 36 is provided so as to be in pressure contact with the fixing roller 35, and is supported so as to be driven to rotate by the rotation driving of the fixing roller 35. The pressure roller 36 assists fixing of the toner image on the recording medium by pressing the toner and the recording medium when the toner is melted and fixed on the recording medium by the fixing roller 35. A pressure contact portion between the fixing roller 35 and the pressure roller 36 is a fixing nip portion. According to the fixing unit 40, the recording medium onto which the toner image is transferred by the transfer unit 30 is sandwiched between the fixing roller 35 and the pressure roller 36, and the toner image is recorded under heating when passing through the fixing nip portion. By being pressed against the medium, the toner image is fixed on the recording medium and an image is formed.

  The recording medium supply unit 50 includes an automatic paper feed tray 37, a pickup roller 38, transport rollers 39 a and 39 b, a registration roller 41, and a manual paper feed tray 42. The automatic paper feed tray 37 is a container-like member that is provided in the lower part of the image forming apparatus 100 in the vertical direction and stores a recording medium. Recording media include plain paper, color copy paper, overhead projector sheets, postcards, and the like. The pickup roller 38 takes out the recording medium stored in the automatic paper feed tray 37 one by one and feeds it to the paper transport path S1. The conveyance rollers 39 a are a pair of roller members provided so as to be in pressure contact with each other, and convey the recording medium toward the registration rollers 41. The registration rollers 41 are a pair of roller members provided so as to be in pressure contact with each other, and the recording medium fed from the conveyance roller 39a is used to convey the toner image carried on the intermediate transfer belt 28 to the transfer nip portion. Synchronously, it is fed to the transfer nip. The manual paper feed tray 42 is a device that takes in the recording medium into the image forming apparatus by manual operation. The recording medium taken in from the manual paper feed tray 42 passes through the paper conveyance path S2 by the conveyance roller 39b, It is fed to the registration roller 41. According to the recording medium supply means 50, a toner image carried on the intermediate transfer belt 28 is conveyed to the transfer nip portion of the recording medium supplied one by one from the automatic paper feed tray 37 or the manual paper feed tray 42. In synchronism with this, it is fed to the transfer nip.

  The discharge means 60 includes a conveyance roller 39 c, a discharge roller 43, and a discharge tray 44. The conveyance roller 39 c is provided on the downstream side of the fixing nip portion in the paper conveyance direction, and conveys the recording medium on which the image is fixed by the fixing unit 40 toward the discharge roller 43. The discharge roller 43 discharges the recording medium on which the image is fixed to a discharge tray 44 provided on the upper surface in the vertical direction of the image forming apparatus 100. The discharge tray 44 stores a recording medium on which an image is fixed.

The image forming apparatus 100 includes a control unit (not shown). For example, the control unit is provided in an upper part of the internal space of the image forming apparatus 100 and includes a storage unit, a calculation unit, and a control unit. In the storage unit of the control means, various setting values via an operation panel (not shown) arranged on the upper surface of the image forming apparatus 100, detection results from sensors (not shown) arranged at various locations inside the image forming apparatus 100, external devices The image information from is input. In addition, programs for executing various means are written. Examples of the various means include a recording medium determination unit, an adhesion amount control unit, and a fixing condition control unit. As the storage unit, those commonly used in this field can be used, and examples thereof include a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD). As the external device, an electric / electronic device that can form or acquire image information and can be electrically connected to the image forming apparatus can be used. For example, a computer, a digital camera, a television receiver, a video recorder, DVD (
Digital Versatile Disc (Recorder), HDDVD (High-Definition Digital Versatile)
Disc), a Blu-ray disc recorder, a facsimile device, a portable terminal device, and the like. The arithmetic unit takes out various data (image formation command, detection result, image information, etc.) written in the storage unit and programs of various means, and performs various determinations. The control unit sends a control signal to the corresponding device according to the determination result of the calculation unit, and performs operation control. The control unit and the calculation unit include a processing circuit realized by a microcomputer, a microprocessor, or the like provided with a central processing unit (CPU). The control means includes a main power supply together with the processing circuit described above, and the power supply supplies power not only to the control means but also to each device in the image forming apparatus 100.

  Thus, the developing device 24 of the present invention can form a high-definition and high-resolution toner image on the photosensitive drum 21 by performing development using the two-component developer of the present invention. Therefore, the image forming apparatus 100 according to the present invention includes the developing device 24 according to the present invention, thereby suppressing the occurrence of filming, improving the fixing property and the transfer efficiency, and forming a high-definition and high-resolution high-quality image. can do.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not particularly limited to these Examples as long as the gist thereof is not exceeded. In Examples and Comparative Examples, a binder resin having an acid value of 5 mgKOH / g or more was determined as a binder resin having polarity, and the others were determined as binder resins having no polarity. Further, a release agent having an acid value of less than 3 mgKOH / g was judged as a low-polarity release agent, and the others were judged as high-polarity release agents.

[Physical property measurement method]
Each physical property value in Examples and Comparative Examples was measured as shown below.

[Glass transition point of binder resin (Tg)]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), according to Japanese Industrial Standard (JIS) K7121-1987, 1 g of a sample (binder resin) was heated at a heating rate of 10 ° C. per minute (10 ° C. / Min), and DSC curve was measured. Draw the endothermic peak corresponding to the glass transition of the obtained DSC curve at a point where the slope is maximum with respect to the straight line that extends the base line on the high temperature side to the low temperature side and the curve from the rising part of the peak to the vertex. The temperature at the intersection with the tangent was determined as the glass transition point (Tg).

[Softening point of binder resin (Tm)]
In a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation), a load (10 kgf / cm ² (9.8 × 10 ⁵ Pa)) was applied and 1 g of a sample (binder resin) was extruded from the die. The sample was heated at a heating rate of 6 ° C./min (6 ° C./min), and the temperature at which half of the sample flowed out of the die was determined as the softening point. A die having a nozzle diameter of 1 mm and a length of 1 mm was used.

[Acid value of binder resin and release agent]
In 50 mL of tetrahydrofuran (THF), 5 g of a sample (binder resin or mold release agent) was dissolved, and after adding a few drops of an ethanol solution of phenolphthalein as an indicator, 0.1 mol / L potassium hydroxide (KOH) Titration was performed with an aqueous solution. The point at which the color of the sample solution changed from colorless to purple was used as the end point, and the acid value (mgKOH / g) was calculated from the amount of potassium hydroxide aqueous solution required to reach the end point and the weight of the sample subjected to titration. .

[Melting point of release agent]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), 1 g of a sample (release agent) was increased from a temperature of 20 ° C. to 200 ° C. at a temperature rising rate of 10 ° C./min (10 ° C./min). The operation of heating and then rapidly cooling from 200 ° C. to 20 ° C. was repeated twice to obtain a DSC curve. Then, the temperature at the top of the endothermic peak corresponding to the melting of the DSC curve obtained by the second operation was determined as the melting point of the release agent.

[Volume average particle diameter ( _D50V ) and coefficient of variation (CV value)]
To 50 ml of electrolytic solution (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), 20 mg of a sample (first or second toner particle group) and 1 ml of sodium alkyl ether sulfate (dispersant) are added, and ultrasonic dispersion is performed. A sample for measurement was prepared by dispersing for 3 minutes at an ultrasonic frequency of 20 kHz using a vessel (trade name: UH-50, manufactured by SMT Co., Ltd.).

About this measurement sample, using a particle size distribution measuring device (trade name: Multisizer 3, manufactured by Beckman Coulter, Inc.), the particle size was measured under the conditions of an aperture diameter of 100 μm and a measurement particle number of 50000 counts. The volume particle size distribution of the sample particles was determined from the measurement results, and the volume average particle size D _50V (μm) was calculated from the determined volume particle size distribution. Moreover, the standard deviation in volume particle size distribution was calculated | required, and the variation coefficient (CV value,%) was computed based on the above-mentioned Formula (1).

Example 1
[Production of First Toner Particle Group]
[First premixing step and first melt-kneading step]
Polyester (binder resin, trade name: FC1494, manufactured by Mitsubishi Rayon Co., Ltd., glass transition point (Tg): 62 ° C., softening point (Tm): 127 ° C., acid value: 6.0) 82.3% by weight (100 Parts by weight), masterbatch (containing 40% by weight of CI Pigment Red 57: 1 (colorant)), 12% by weight (14.6 parts by weight), paraffin wax (release agent, trade name: HNP11, Japan) Made by Seiki Co., Ltd., melting point: 68 ° C., acid value: 1.0 or less) 4.2% by weight (5.1 parts by weight), alkyl salicylic acid metal salt (charge control agent, trade name: BONTRON E-84, Orient A toner raw material containing 1.5% by weight (1.8 parts by weight) of Chemical Co., Ltd. in a mixing ratio was mixed for 10 minutes by a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.). Then, the obtained toner raw material mixture was melt-kneaded with a twin-screw extrusion kneader (trade name: PCM-65, manufactured by Ikegai Co., Ltd.) to obtain a first melt-kneaded product.

[First grinding step]
After the first melt-kneaded product obtained in the first premixing step and the first melt-kneading step is cooled to room temperature and solidified, a cutting mill (trade name: VM-16, manufactured by Ryoko Sangyo Co., Ltd.) ). Subsequently, the coarsely pulverized product obtained by coarse pulverization was pulverized by a fluidized bed type jet pulverizer (trade name: Counterjet Mill, manufactured by Hosokawa Micron Corporation) to obtain a first pulverized product.

[First classification step]
From the pulverized product obtained in the pulverization step, the excessively pulverized toner particles were classified and removed using a rotary air classifier (manufactured by Hosokawa Micron Corporation) to produce a first toner particle group having a volume average particle size of 5.5 μm. .

[Production of Second Toner Particle Group]
[Second Premixing Step and Second Melt-Kneading Step]
Polyester (binder resin, trade name: FC1469, manufactured by Mitsubishi Rayon Co., Ltd., glass transition point (Tg): 62 ° C., softening point (Tm): 120 ° C., acid value: 6.0) 82.3% by weight (100 Parts by weight), masterbatch (containing 40% by weight of CI Pigment Red 57: 1 (colorant)), 12% by weight (14.6 parts by weight), carnauba wax (release agent, trade name: REFINED CARNAUBA WAX) , Manufactured by Kato Yoko Co., Ltd., melting point: 83 ° C., acid value: 8.0, 4.2 wt% (5.1 parts by weight), alkyl salicylic acid metal salt (charge control agent, trade name: BONTRON E-84, Orient Toner raw material containing 1.5 wt% (1.8 parts by weight) of Chemical Co., Ltd. in this blending ratio is mixed for 10 minutes by a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.). . It was then resulting toner raw material mixture biaxial extrusion kneader (trade name: PCM-65, Ltd. Ikegai) to obtain a second melt-kneaded product was melt-kneaded.

[Second grinding step]
After the second melt-kneaded product obtained in the second premixing step and the second melt-kneading step is cooled to room temperature and solidified, a cutting mill (trade name: VM-16, Ryoko Sangyo Co., Ltd.) Coated). Subsequently, the coarsely pulverized product obtained by the coarse pulverization was pulverized by a fluidized bed type jet pulverizer (trade name: Counterjet Mill, manufactured by Hosokawa Micron Corporation) to obtain a second pulverized product.

[Second classification step]
In the second pulverized product obtained in the second pulverization step, the excessively pulverized toner particles are classified and removed by a rotary air classifier (manufactured by Hosokawa Micron Corporation), and the volume average particle diameter is 4.0 μm, the coefficient of variation ( A second toner particle group having a CV value of 25% was prepared.

[Production of toner]
[Mixing process]
After adding 1.2 parts by weight of silica fine particles (external additive, trade name: R972, manufactured by Nippon Aerosil Co., Ltd.) to 100 parts by weight of each of the first toner particle group and the second toner particle group, The first toner particle group and the second toner particle group are mixed and stirred by a mixer (trade name: Henschel mixer, manufactured by Mitsui Mining Co., Ltd.) so that the content of the second toner particle group is 18% by weight. As a result, the toner of Example 1 was produced.

(Example 2)
Polyester similar to that used in the first premixing step as the binder resin in the second premixing step (binding resin, trade name: FC1494, manufactured by Mitsubishi Rayon Co., Ltd., glass transition point (Tg) The toner of Example 2 was produced in the same manner as in Example 1 except that: 62 ° C., softening point (Tm): 127 ° C., acid value: 6.0) was used.

(Example 3)
The toner of Example 3 was produced in the same manner as in Example 1 except that the classification conditions were adjusted so as to produce a first toner particle group having a volume average particle diameter of 7.2 μm in the first classification step. .

Example 4
Except for adjusting the classification conditions so as to produce a second toner particle group having a volume average particle size of 5.2 μm and a coefficient of variation (CV value) of 25% in the second classification step, the same as in Example 1. Thus, the toner of Example 4 was produced.

(Example 5)
In the first classification step, the classification conditions are adjusted so as to produce a first toner particle group having a volume average particle size of 3.8 μm, and in the second classification step, the volume average particle size is changed to 3.3 μm. A toner of Example 5 was produced in the same manner as in Example 1 except that the classification conditions were adjusted to produce a second toner particle group having a coefficient (CV value) of 25%.

(Example 6)
Except for adjusting the classification conditions so as to produce a second toner particle group having a volume average particle diameter of 2.8 μm and a coefficient of variation (CV value) of 25% in the second classification step, the same as in Example 1. Thus, the toner of Example 4 was produced.

(Example 7)
In the first premixing step, polyester (binder resin, trade name: FC1494, manufactured by Mitsubishi Rayon Co., Ltd., glass transition point (Tg): 62 ° C., softening point (Tm): 127 ° C., acid value: 6. 0) 82.7% by weight (100 parts by weight), masterbatch (containing 40% by weight of CI Pigment Red 57: 1 (colorant)), 12% by weight (14.5 parts by weight), paraffin wax (released) Mold, trade name: HNP11, manufactured by Nippon Seiki Co., Ltd., melting point: 68 ° C., acid value: 1.0 or less) 3.8% by weight (4.6 parts by weight), alkylsalicylic acid metal salt (charge control agent, A toner of Example 7 was produced in the same manner as in Example 1 except that 1.5% by weight (1.8 parts by weight) (trade name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.) was used.

  That is, the toner of Example 7 is different from the toner of Example 1 in the amount of paraffin wax (release agent) added in the first premixing step.

(Example 8)
In the second premixing step, polyester (binder resin, trade name: FC1469, manufactured by Mitsubishi Rayon Co., Ltd., glass transition point (Tg): 62 ° C., softening point (Tm): 120 ° C., acid value: 6. 0) 82.7% by weight (100 parts by weight), masterbatch (containing 40% by weight of CI Pigment Red 57: 1 (colorant)), 12% by weight (14.5 parts by weight), carnauba wax (released) Molding agent, trade name: REFINED CARNAUBA WAX, manufactured by Hiroyuki Kato Co., Ltd., melting point: 83 ° C., acid value 8.0) 3.8% by weight (4.6 parts by weight), metal alkylsalicylate (charge control agent, product) Name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.) Toner of Example 8 was produced in the same manner as in Example 1 except that 1.5% by weight (1.8 parts by weight) was used.

  That is, the toner of Example 8 is different from the toner of Example 1 in the amount of carnauba wax (release agent) added in the second premixing step.

Example 9
Except for using a paraffin wax (release agent, trade name: HNP10, manufactured by Nippon Seiki Co., Ltd., melting point: 75 ° C., acid value: 1.0 or less) as a release agent in the first premixing step. The toner of Example 9 was produced in the same manner as in Example 1.

(Example 10)
A toner of Example 10 was produced in the same manner as in Example 1, except that the content of the second toner particle group was 23% by weight in the mixing step.

(Example 11)
A toner of Example 11 was produced in the same manner as in Example 1, except that the content of the second toner particle group was 1.5% by weight in the mixing step.

(Comparative Example 1)
Paraffin wax similar to that used in the first premixing step as the release agent in the second premixing step (release agent, trade name: HNP11, manufactured by Nippon Seiki Co., Ltd., melting point: 68 ° C. The toner of Comparative Example 1 was produced in the same manner as in Example 1 except that the acid value was 1.0 or less.

(Comparative Example 2)
Carnauba wax similar to that used in the second premixing step as the release agent in the first premixing step (release agent, trade name: REFINED CARNAUBA WAX, manufactured by Kato Hiroyuki, melting point: 83 The toner of Comparative Example 2 was produced in the same manner as in Example 1 except that the temperature was 8.0 ° C. and the acid value was 8.0).

(Comparative Example 3)
In the first pre-mixing step, carnauba wax (release agent, trade name: REFINED CARNAUBA WAX, manufactured by Hiroyuki Kato Co., Ltd., melting point: 83 ° C., acid value 8.0) is used as the release agent. Except for using a paraffin wax (release agent, trade name: HNP11, manufactured by Nippon Seiki Co., Ltd., melting point: 68 ° C., acid value: 1.0 or less) as a release agent in the pre-mixing step. The toner of Comparative Example 3 was produced in the same manner as Example 1.

  In the toners of Examples 1 to 11 and Comparative Examples 1 to 3, the acid value and softening point (Tm) of the binder resin used in the first and second toner particle groups, the acid value of the release agent, and the content Table 1 shows the melting point, the particle size distribution of each toner particle group, and the content of the second toner particle group in the toner.

[Manufacture of two-component developer]
A ferrite core carrier having a volume average particle diameter of 45 μm was used as the carrier, and a V-type mixer (trade name) was used so that the coverages of the toners of Examples 1 to 11 and Comparative Examples 1 to 3 with respect to this carrier were 60%. : V-5, manufactured by Tokuju Kogyo Co., Ltd.), toner and carrier were mixed for 20 minutes to produce a two-component developer.

[Evaluation]
Using the two-component developers each containing the toners of Examples 1 to 11 and Comparative Examples 1 to 3, filming, fixing properties, transfer efficiency, image reproducibility, and toner scattering were evaluated by the following methods. Table 2 shows the results of each evaluation and the results of comprehensive evaluation.

[Filming]
Toner adhesion amount is 0.6mg ^/ cm ² ~0.7mg ^/ cm 2 next to the developing roller, the toner adhesion amount of the single-color solid portion of the unfixed toner image formed on the recording paper with 0.5 mg / cm ² Then, a continuous live-action test was performed in which an evaluation chart having a document density of 5% including an image solid portion and a character portion was formed on 10000 sheets of recording paper with each toner single color. After a continuous live-action test of 10,000 sheets, a solid image corresponding to the actual length of the developing roller and the photosensitive member in the longitudinal direction is output, and the obtained solid image is visually observed to create a streak or fill in the solid image. The presence or absence of ming marks was determined. Also, the surface of the photoreceptor was visually observed to determine the presence or absence of filming. The evaluation criteria are as follows.
○: There is no problem on the image and the surface of the photoreceptor.
Δ: There is no problem on the image, but filming is confirmed on the surface of the photoreceptor.
X: Problems are confirmed both on the image and on the surface of the photoreceptor.

[Fixability]
Using a modified color copier (trade name: MX-2700, manufactured by Sharp Corporation) on a recording paper (trade name: PPC paper SF-4AM3, manufactured by Sharp Corporation), a rectangle 20 mm long and 50 mm wide. A sample image including a solid image portion is adjusted so that the amount of toner adhering to the recording paper in an unfixed state in the solid image portion is 0.5 mg / cm ² to form an unfixed image. A fixed image was prepared using an external fixing device prepared using a fixing unit of a copying machine. The fixing process speed is 124 mm / sec, the fixing roller temperature is increased from 130 ° C. in increments of 5 ° C., the surface temperature range of the fixing roller where neither low-temperature offset nor high-temperature offset occurs is obtained, ° C). The minimum value in the non-offset region was the minimum fixing temperature (° C.), and the maximum value in the non-offset region was the high temperature offset occurrence temperature (° C.).

Further, the definition of high temperature and low temperature offset is that the toner does not fix to the recording paper during fixing but adheres to the recording paper after the roller makes a full rotation while adhering to the fixing roller.
A: The fixing non-offset region is 60 ° C. or higher.
○: The fixing non-offset region is 45 ° C. or higher and lower than 60 ° C.
Δ: Fixing non-offset region is 35 ° C. or higher and lower than 45 ° C.
X: The fixing non-offset region is less than 35 ° C.

[Transfer efficiency]
The transfer efficiency is a ratio of the toner transferred from the surface of the photosensitive drum to the intermediate transfer belt in the primary transfer, and the ratio of the toner amount existing on the photosensitive drum before the transfer is calculated as 100%. The amount of toner present on the photosensitive drum before transfer is obtained by sucking the amount of toner present on the photosensitive drum before transfer using a charge amount measuring device (trade name: 210HS-2A, manufactured by Trek Japan Co., Ltd.) It was obtained by measuring the amount of this sucked toner. The amount of toner transferred to the intermediate transfer belt was also obtained in the same manner. The evaluation criteria are as follows.
A: Transfer efficiency is 95% or more.
○: Transfer efficiency is 90% or more and less than 95%.
Δ: Transfer efficiency is 85% or more and less than 90%.
X: Transfer efficiency is less than 85%.

[Image reproducibility]
In a condition that an image density is 0.3 by a color copier (trade name: MX-2700, manufactured by Sharp Corporation), and a halftone image having a diameter of 5 mm can be copied at an image density of 0.3 to 0.5, An original on which an original image of a fine line having a line width of exactly 100 μm was copied, and the obtained copy image was used as a measurement sample. The line width of the thin line formed on the measurement sample by the indicator was measured from a monitor image obtained by enlarging the measurement sample 100 times using a particle analyzer (trade name: Luzex 450, manufactured by Nireco Corporation). Since the thin line has irregularities and the line width varies depending on the measurement position, the line width is measured at a plurality of measurement positions and an average value is obtained, and this line width is taken as the line width of the measurement sample. The line width of the measurement sample was divided by the original line width of 100 μm, and the obtained value was multiplied by 100 to obtain a fine line reproducibility value. The closer this fine line reproducibility value is to 100, the better the fine line reproducibility, the better the image reproducibility, and the better the resolution. The evaluation criteria are as follows. The image density indicates an optical reflection density measured by a reflection densitometer (trade name: RD-918, manufactured by Macbeth Co.).
A: Fine line reproducibility is 100 or more and less than 105.
A: Fine line reproducibility value is 105 or more and less than 115.
(Triangle | delta): The value of fine line reproducibility is 115-125.
X: The fine line reproducibility value is 125 or more.

[Toner scattering]
The developer tank of a color copier (trade name: MX-2700, manufactured by Sharp Corporation) is filled with a two-component developer, and the developer tank is idled for 3 hours in a high-temperature and high-humidity environment at a temperature of 35 ° C. and a relative humidity of 80%. It was. The difference in toner concentration in the two-component developer before and after the start of idling was determined, and the toner scattering was evaluated based on the following evaluation criteria for the obtained difference value.
A: Very good. The difference in toner density is less than 0.5% with respect to the toner density before starting idling.
○: Good. The difference in toner density is 0.5% or more and less than 1% with respect to the toner density before starting idling.
Δ: No problem in actual use. The difference in toner density is 1% or more and less than 1.5% with respect to the toner density before starting idling.
X: Defect. The difference in toner density is 1.5% or more with respect to the toner density before starting idling.

[Comprehensive evaluation]
The evaluation criteria for comprehensive evaluation are as follows.
A: Very good. There are no Δ and × in each evaluation result.
○: Good. In each evaluation result, there is no x and Δ is one.
Δ: No problem in actual use. Each evaluation result has no x and Δ is 2 or more.
X: Defect. There is at least one x in each evaluation result.

  From the results shown in Table 2, the two-component developer using the toners of Examples 1 to 11 in the present invention is superior to the two-component developers of Comparative Examples 1 to 3 as follows. Is clear.

  In the two-component developer using the toners of Examples 1 to 11, a release agent having a low polarity with respect to the binder resin is used for the first toner particle group, and the binder is applied to the second toner particle group. Since a high-polarity release agent is used for the resin, it is possible to obtain a high-quality image with little filming and toner scattering, good fixability and transfer efficiency, and excellent image reproducibility.

  On the other hand, in the two-component developer using the toner of Comparative Example 1, since a release agent having a low polarity relative to the binder resin is used for the second toner particle group, the dispersion of the release agent in the small particle size toner is performed. The property deteriorated and the occurrence of filming was observed. Also, transfer efficiency deteriorated.

  Further, in the two-component developer using the toner of Comparative Example 2, the dispersibility in the large particle size toner is improved because a release agent having a high polarity with respect to the binder resin is used for the first toner particle group. As a result, deterioration of fixability was observed.

  The two-component developer using the toner of Comparative Example 3 uses a release agent having a high polarity with respect to the binder resin for the first toner particle group, and the binder resin for the second toner particle group. On the other hand, since a low-polarity release agent was used, filming was observed, and transfer efficiency and fixability deteriorated.

  In this embodiment, as a toner for electrophotography, C.I. I. Although magenta toner containing CI Pigment Red 57: 1 is exemplified, the present invention is not limited to this, and other toners containing the various colorants exemplified above may be used in place of the above colorants. This embodiment can be implemented.

It is a flowchart which shows an example of the procedure of the manufacturing method of the toner of this invention. FIG. 3 is a diagram schematically illustrating an example of a configuration of an image forming apparatus suitable for using the toner of the present invention. FIG. 2 is a diagram schematically illustrating an example of a configuration of a developing device suitable for using the toner of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 20 Toner image forming means 30 Transfer means 40 Fixing means 50 Recording medium supply means 60 Ejecting means 21 Photoconductor drum 22 Charging means 23 Exposure unit 24 Developing device 25 Cleaning unit 26 Developing tank 27 Toner hopper 28 Intermediate transfer belt 29 Drive Roller 31 Follower roller 32 Intermediate transfer roller 33 Transfer belt cleaning unit 34 Transfer roller 35 Fixing roller 36 Pressure roller 37 Automatic paper feed tray 38 Pickup roller 39 Transport roller 41 Registration roller 42 Manual feed tray 43 Discharge roller 44 Discharge tray

Claims (12)

A first toner particle group including at least a first binder resin having polarity, a first colorant, and a first release agent having a low polarity with respect to the first binder resin;
A second binder resin having at least polarity, a second colorant, and a second release agent having a high polarity with respect to the second binder resin, and having a volume average particle diameter larger than that of the first toner particle group. And a second toner particle group having a small particle size.   The toner according to claim 1, wherein the first and second binder resins have an acid value of 5 mgKOH / g or more.   The toner according to claim 1 or 2, wherein the first release agent has an acid value of less than 3 mgKOH / g, and the second release agent has an acid value of 3 mgKOH / g or more.   The toner according to claim 1, wherein the softening point of the first binder resin is higher than the softening point of the second binder resin.   The toner according to claim 1, wherein the first and second binder resins contain a polyester resin.   The toner according to claim 1, wherein the first release agent has a melting point of 70 ° C. or less. A method for producing a toner according to any one of claims 1 to 6,
First before producing the first mixture by mixing the first binder resin having at least polarity, the first colorant, and the first binder resin with the low-polarity first release agent. A mixing step;
A first melt-kneading step of producing a first melt-kneaded product by melt-kneading the first mixture;
A first pulverization step of pulverizing the first melt-kneaded product to produce a first pulverized product;
A first classification step of classifying the first pulverized product to produce a first toner particle group;
Second before producing the second mixture by mixing the second binder resin having at least polarity, the second colorant, and the second binder resin having a high polarity with the second binder resin. A mixing step;
A second melt-kneading step of melt-kneading the second mixture to produce a second melt-kneaded product;
A second pulverization step of pulverizing the second melt-kneaded product to produce a second pulverized product;
A second classification step of classifying the second pulverized product to produce a second toner particle group having a volume average particle size smaller than that of the first toner particle group;
A method for producing toner, comprising: a mixing step of mixing the first toner particle group and the second toner particle group.   8. The toner according to claim 7, wherein the volume average particle size of the first toner particle group is 4 μm or more and 7 μm or less, and the volume average particle size of the second toner particle group is 3 μm or more and 5 μm or less. Production method.   In the first premixing step, 4.0% by weight or more of the first release agent is mixed with respect to the first mixture, and in the second premixing step, the second release agent is mixed with the second mixture. The toner production method according to claim 7, wherein 4.0% by weight or more is mixed with respect to the toner.   A two-component developer comprising the toner according to any one of claims 1 to 6 and a carrier.   A developing device that performs development using the two-component developer according to claim 10.   An image forming apparatus comprising the developing device according to claim 11.

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