JP2012063574A - Magnetic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic toner which enhances offset resistance under a low temperature and low humidity environment, and can output excellent image quality even when being stored under a severe environment such as a high temperature and high humidity environment.SOLUTION: In the magnetic toner having magnetic toner particles containing a binder resin, a magnetic material and a mold-releasing agent, and an inorganic fine powder, the surface of the magnetic material is treated with a fatty acid or a fatty acid metal salt, the wettability Wa of the magnetic toner particles at 25°C is 30 vol.% or more and 50 vol.% or less, the wettability Wb of the magnetic toner particles at 50°C is 55 vol.% or less, and the wettability Wc of the magnetic toner particles at 70°C satisfies Wc-Wa≥40.

Description

  The present invention relates to a magnetic toner used for image formation in electrophotography.

  In recent years, copying machines and printers have been required to reduce the size of the main body in consideration of space saving. Therefore, it is essential to reduce the size of the fixing device as well as the size of the cartridge and the like, and simplification of the device by an external heating method is provided as a solution (see Patent Document 1). The external heating method heats an image heating member (hereinafter referred to as a fixing roller) that can be rotated by a low heat capacity heating means such as a small-diameter heating roller incorporating a ceramic heater or a halogen heater from the outside. Can be rapidly heated. Although the external heating method is excellent in downsizing and on-demand characteristics, since the heat of the heater cannot be efficiently transferred to the paper, a heat storage layer containing aluminum oxide and / or zinc oxide is formed on the outermost layer of the film. ing. As a result, the heat storage layer of the heater has a large amount of fillers such as aluminum oxide and zinc oxide, so that the releasability during fixing is disadvantageous. Countermeasures from the toner are also required for such a deterioration in releasability.

  In addition, a one-component magnetic development method is adopted in the development process because of demands for miniaturization, weight reduction, and high reliability. The one-component magnetic development method is a method in which magnetic particles are encapsulated in toner and the developer is carried and conveyed by the action of magnetic force. However, the development part is reduced in size by eliminating the need for a carrier and reducing the number of cartridge parts. Is effective. However, in the one-component magnetic development method, since the toner carrying / restriction is regulated by the magnetic force in the developing unit, it is a problem for achieving high image quality to uniformly disperse the magnetic material.

  In order to improve releasability with a one-component magnetic toner, a prescription in which a large amount of a release agent is added can be considered. However, the one-component magnetic toner is likely to be contaminated with the release agent due to friction with other members or friction between toners. In particular, in a high temperature and high quality environment, the release agent oozes out and the binder is plasticized easily, which may cause image defects due to fusion of the electrostatic charge image carrier. Further, when left in a high-temperature and high-humidity environment for a long period of time, it tends to cause a decrease in density or blocking due to the release of the release agent contained in the toner. There is a room for improvement because there is a trade-off between improving the releasability and durability and storage stability.

  To solve such a problem, an improvement of a one-component magnetic toner has been proposed. First, in order to improve the dispersibility of a magnetic material with a one-component magnetic toner, the surface of the magnetic material has been improved. In toner production by a pulverization method, a magnetic material in which a mixture of a magnetic material and a fatty acid or a fatty acid metal salt is placed in a Henschel mixer or the like and the surface of the magnetic material is coated with a fatty acid or a fatty acid metal salt is used (see Patent Document 2). ). Thereby, magnetic toner dispersibility can be improved as compared with the prior art, and a magnetic toner having high resolution, high fine lines, and excellent gradation reproducibility is provided. However, when a large amount of a release agent is added to improve the releasability, the magnetic toner containing the above-mentioned magnetic substance easily causes poor charging after severe storage, and there is room for improvement in terms of storage stability. In addition, in the production of magnetic toners by suspension polymerization, in order to improve the dispersibility of the magnetic material, a method is proposed in which the surface of the magnetic material is coated with an inorganic silane coupling agent and then subjected to a hydrophobizing treatment ( (See Patent Document 3). As a result, a magnetic toner having a good dispersion state of the magnetic material, an excellent image free from fogging, and a sharp particle size distribution is provided. However, the magnetic toner containing the magnetic material described above has room for improvement in terms of releasability because the releasability of the fixing device is low in a fixing device using an external heating method.

  Furthermore, in the magnetic toner by the suspension polymerization method, there is a method in which the magnetic material is coated with an organic substance such as a release agent after the magnetic material is coated with a silane coupling agent in order to improve the releasability which has been a problem described above. It has been proposed (see Patent Document 4). In this method, the surface of the magnetic material is pretreated with a silane coupling agent, and then the surface is coated with a release agent using a Henschel mixer or the like. By treating the surface of the magnetic material with a release agent, the dispersibility of the release agent in the toner particles is enhanced, and a toner with improved developability and release properties is provided. However, if a large amount of a release agent is added to improve the releasability in the above magnetic toner, charging failure is likely to occur after severe storage, and there is room for improvement in terms of storability.

  In these conventional techniques, the developing property and releasability of the toner are improved separately. However, there is room for improvement in order to improve the durability accompanying environmental changes and developability after severe storage, and to improve the releasability on a high-speed machine.

JP 2008-299314 A Japanese Patent Laid-Open No. 04-335358 JP 2009-109827 A JP 2005-107519 A

  An object of the present invention is to provide a magnetic toner that solves the above problems. Therefore, the object of the present invention is to have excellent releasability in a low temperature and low humidity environment, and to output excellent image quality even when stored for a certain period of time in a durability test accompanied by environmental changes or in a high temperature and high humidity environment. It is to provide a magnetic toner that can be used.

The present invention is a magnetic toner having at least a magnetic toner particle having at least a binder resin, a magnetic material, and a release material, and an inorganic fine powder,
The surface of the magnetic material is treated with a fatty acid or a fatty acid metal salt;
The magnetic toner particles have a methanol wettability Wa of 25 ° C. of 30% by volume or more and 50% by volume or less, a methanol wettability Wb of 50 ° C. of 55% by volume or less, and a methanol wettability Wc of 70 ° C. The present invention relates to a magnetic toner characterized by satisfying
Wc−Wa ≧ 40 (Formula 1)

  According to the present invention, it is possible to provide a magnetic toner having excellent releasability in a low temperature and low humidity environment. Further, it is possible to provide a toner capable of outputting an excellent image even in a durability test under a severe condition in a high temperature and high humidity environment or when stored in a severe environment for a certain period.

1 is a schematic view of an image forming apparatus that can suitably use the toner of the present invention. FIG. 3 is a schematic view of a fixing roller used in the fixing property test of the present invention. FIG. 2 is a schematic cross-sectional view of a fixing device used in a fixing test of the present invention.

  The present invention relates to a magnetic toner, and with respect to an image forming method, a conventionally known electrophotographic process can be applied and is not particularly limited.

  In the present invention, the surface of a magnetic material, which is a component of magnetic toner particles, is treated with a fatty acid or a fatty acid metal salt. The magnetic toner particles have a methanol wettability of 25 ° C. Wa and a methanol wettability of 50 ° C. Wb. When the methanol wettability at 70 ° C. is Wc, the value of Wa is 30% by volume to 50% by volume, the value of Wb is 55% by volume or less, and the value of Wc-Wa is 40% by volume or more. It is characterized by being.

  As a result of intensive studies by the present inventors, the above configuration has greatly improved the fixability and releasability of the conventional product in a low temperature and low humidity environment (15 ° C., 10%). Furthermore, even in image output after severe storage stored at 40 ° C. for 30 days, a high-quality image could be output. Also, in an endurance test accompanied by an environmental change from a normal temperature and normal humidity environment to a high temperature and high quality environment, it was possible to output the image without causing adverse effects. The present inventors consider that the present invention is effective for the following reasons.

  The magnetic material used in the magnetic toner of the present invention is characterized in that the surface of the magnetic material is treated with a fatty acid or a fatty acid metal salt. Furthermore, the 25 ° C. methanol wettability Wa of the magnetic toner particles is 30% by volume or more and 50% by volume or less, the 50 ° C. methanol wettability Wb is 55% by volume or less, and the 70 ° C. methanol wettability Wc is Wc−. It was confirmed that the magnetic toner characterized by satisfying Wa ≧ 40 satisfies the desired requirements. The magnetic material is characterized in that the surface of the magnetic material is coated with a fatty acid or a fatty acid metal salt, thereby improving the uniformity of the surface of the magnetic material. Since the magnetic substance is bonded in a state where the orientation of the treatment agent is uniform, the magnetic substance surface has a surface characteristic that is uniformly treated with a fatty acid.

That the 50 ° C. wettability Wb of the toner particles is 55% by volume or less indicates that the amount of the release agent exuded onto the toner surface in a high temperature and high humidity environment or a severe environment is small. Compared with the 25 ° C. wettability Wa, a toner having no change in value means that the environmental change is small and the storage stability is good. Further, when the 70 ° C. wettability Wc of the magnetic toner particles satisfies the following formula 1,
Wc−Wa ≧ 40 (Formula 1)

  This means that the release of the release agent to the surface of the magnetic toner during heating is quick, and that the releasability of the magnetic toner during fixing is improved. That is, when heated at the time of fixing, the release agent exudes quickly to the toner surface layer, so that the offset resistance can be improved. On the other hand, when the difference of Wc-Wa is less than 40, the amount of the release agent that oozes out on the toner surface layer during fixing is small, so that an image defect is caused by an offset phenomenon in which the toner adheres to the fixing film. Further, even when Wc−Wa ≧ 40, when the 25 ° C. wettability Wa and the 50 ° C. wettability Wb are not in the range of 30% by volume or more and 50% by volume or less and 55% by volume or less, respectively, the magnetic toner is used in a severe environment. Since the release agent that exudes to the particle surface increases, sufficient storage stability cannot be obtained.

  In order for the magnetic toner to be included in the above wettability range, a structure in which the release agent is finely dispersed around the fatty acid-treated magnetic material is preferable. In order to form such a structure, the present inventors pay attention to the interaction between the fatty acid magnetic substance and the release agent, and suppress the release agent exudation in a harsh environment and the release agent stain at the time of fixing. Balanced both promotion and promotion.

  The toner that falls within the above wettability range has a toner structure in which a release agent is finely dispersed around the fatty acid-treated magnetic material. This is because the carbon chain of the bonded fatty acid and the carbon chain of the release agent have hydrophobic properties, so that an intermolecular force works between the magnetic substance and the release agent. First, since the surface of the magnetic material is uniformly coated with fatty acid, the magnetic material dispersibility is improved. As a result, the intermolecular force between the magnetic substance and the release agent works. Therefore, a characteristic toner structure in which the release agent is finely dispersed around the magnetic body is formed by the interaction between the magnetic body and the release agent. In such a toner structure, a release agent is present around the magnetic material, so that the methanol wettability Wa at 25 ° C. is 30% by volume or more and 50% by volume or less, and the methanol wettability Wb at 50 ° C. is 55% by volume or less. The methanol wettability Wc at 70 ° C. satisfies Wc−Wa ≧ 40. Since the release agent is dispersed around the magnetic material at the time of fixing, the heat is efficiently transmitted to the release agent before the heat is absorbed by the magnetic material. As a result, the release rate of the release agent during fixing is increased. Further, the intermolecular force acting on the magnetic substance and the release agent suppresses the release of the release agent in a high temperature and high humidity environment or a severe environment.

  Therefore, considering the behavior of the toner at the time of fixing, the heated and pressurized toner is plasticized and deformed by the release agent contained in the toner, and the melted toner adheres to the recording material. Further, when the release agent oozes out from the inside of the toner, the toner is peeled off from a fixing member such as a heat roll or a heat-resistant film or an opposing pressure roller. As a result, the image is fixed on the recording material as a fixed image. By releasing the release agent quickly at the time of fixing, it is possible to improve the release property that promotes peeling from the fixing member. Further, by finely dispersing the release agent around the magnetic material, the release agent and the resin are compatible around the magnetic material, and the fixing start temperature can be lowered by plasticizing the resin.

  In the conventional production method in which fatty acid is attached to the surface of a magnetic material, the fatty acid cannot be coated with the magnetic material uniformly oriented. For this reason, the intermolecular force acting as an interaction between the magnetic substance and the release agent is weakened. When the interaction between the magnetic material and the release agent becomes weak, the release agent and the magnetic material are separated from each other at different locations. For this reason, even in a toner to which a large amount of a release agent is added, heat applied during fixing is absorbed by the magnetic material, and the rate of seeping of the release agent during fixing becomes slow. Furthermore, when the number of parts added to the mold release agent is increased, the amount of the mold release agent exuded in a high-temperature and high-humidity environment increases, so that the storage stability is deteriorated.

  In addition, in a magnetic toner produced by a conventional suspension polymerization method, there is also a technique in which a magnetic material whose surface is coated with a silane coupling agent and a release agent are added in a large amount. However, encapsulating the release agent increases the environmental stability in a high-temperature and high-humidity environment, but the release amount of the release agent at the time of fixing is small, so that the release property is deteriorated. In the present invention, since a magnetic material in which fatty acid is uniformly and firmly bonded on the surface of the magnetic material is used, a toner whose wettability falls within the above-mentioned claims can be produced. That is, in the present invention, since the surface of the magnetic material is uniformly treated with fatty acid, the intermolecular force between the magnetic material and the release agent is increased, and the affinity is greatly improved. This is considered to enable a toner structure in which a release agent is finely dispersed around a magnetic material different from the conventional toner structure.

  As described above, the magnetic toner in which the release agent is finely dispersed around the magnetic material becomes a magnetic toner having high plasticity and a structure in which the release agent is easily leached even when heated by an external heating type fixing device. For this reason, it is possible to provide a magnetic toner having both fixing ability, releasability, durability and storage stability.

  In the present invention, the fatty acid or fatty acid metal salt having a carbon number Cm of 14 or more and 24 or less is referred to as the fatty acid or fatty acid metal salt in the present invention. That is, a fatty acid as referred to in the present invention has a longer carbon chain than myristic acid and a shorter carbon chain than lignoceric acid.

  In particular, when the affinity with the release agent is taken into consideration, the carbon number Cm of the fatty acid or the fatty acid containing the carbonyl carbon of the fatty acid metal salt is preferably 16 or more and 22 or less. When the fatty acid or fatty acid metal salt is a fatty acid having a longer carbon chain than palmitic acid and a shorter carbon chain than behenic acid, the affinity between the release agent carbon chain and the fatty acid carbon chain is increased. In the case of palmitic acid and palmitic acid metal salt, the release agent and the magnetic substance are attracted by the intermolecular force for suppressing the release of the release agent in the binder. As a result, the release agent dispersed around the magnetic material is prevented from oozing out on the toner surface during severe storage (40 ° C. × 30 days). On the other hand, when behenic acid and behenic acid metal salt are used, fatty acid or fatty acid metal salt can be uniformly dispersed in an aqueous medium, so that the surface of the magnetic material is uniformly covered with fatty acid or fatty acid metal salt. be able to. As a result, the intermolecular force between the magnetic substance and the release agent becomes stronger, so that the release agent can be further finely dispersed, and the releasability and fixability due to exudation of the release agent during heating can be improved. .

  In the present invention, all known release agents can be used, and among them, ester wax is preferable. More preferably, a monofunctional or bifunctional ester wax is more preferable. Since the ester group portion having a long carbon chain of ester wax is similar to the ester group portion having a long chain carbon chain of fatty acid bonded to the surface of the magnetic material, there is a difference between the magnetic material and the release agent. Hydrogen bonding occurs. As a result, the affinity between the magnetic substance and the release agent is increased, the release agent is more easily dispersed around the magnetic substance, and the exudation of the ester wax is easily promoted during a fixing test in a low temperature and low humidity environment. . Thereby, a further effect is brought about by the fixing property and the releasing property. Since monofunctional or bifunctional ester waxes are linear, they are more susceptible to interaction between ester groups than bulky ester waxes such as penta or dipenta. For this reason, the monofunctional or bifunctional ester wax is finely dispersed in the vicinity of the magnetic substance, so that it easily oozes out on the toner surface at the time of fixing and has a high effect on releasability. On the other hand, bulky ester wax has high plasticity to the resin, but since there are few dispersed in the vicinity of the magnetic material, it is difficult to obtain an effect on releasability in the fixing test.

In the present invention, when the carbon number of the fatty acid containing the carbonyl carbon of the fatty acid or fatty acid metal salt is Cm, the carbon number of the alcohol component of the ester wax is Cwa, and the carbon number of the acid component is Cwb, Cm, Cwa and Cwb are as follows: When Expressions 2 and 3 are satisfied, the fixing start temperature and the offset resistance in a low temperature and low humidity environment can be improved.
| Cm-Cwa | ≦ 6 (Formula 2)
| Cm−Cwb | ≦ 6 (Formula 3)

  That is, the smaller the difference between the carbon number of the fatty acid containing the carbonyl carbon of the fatty acid or fatty acid metal salt, the carbon number of the alcohol component of the ester wax, and the carbon number of the acid component, the more similar the hydrophobicity. For this reason, a strong intermolecular force is formed, and the affinity between the magnetic substance and the ester wax is increased. Due to this affinity, the release agent is easily finely dispersed in the toner particles, so that the plasticity at the time of fixing is increased. Further, at 30 ° C., the release of the release agent to the toner surface is suppressed. Therefore, it is possible to improve the durability at which the resolution hardly deteriorates even when the fixing start temperature in the low temperature and low humidity environment and the environmental change to the high temperature and high quality environment in the second half of the durability.

  In the present invention, the fatty acid or fatty acid metal salt coats the surface of the magnetic substance at a ratio of 1.5% by mass or more and 5.0% by mass or less with respect to 100% by mass of the magnetic substance, and the treatment is carried out in the aqueous phase. Preferably it is done. At this time, the amount of fatty acid deposited was evaluated using a trace carbon analyzer (EMIA-100 type manufactured by Horiba). When the fatty acid or fatty acid metal salt is 1.5% by mass or more with respect to 100% by mass of the magnetic substance, sufficient hydrophobicity can be obtained. As a result, the release agent is uniformly dispersed around the magnetic substance in the magnetic toner particles, and thus the offset resistance can be improved. Moreover, aggregation of a magnetic body can be prevented when a fatty acid or a fatty acid metal salt is 5.0 mass% or less with respect to 100 mass% of magnetic bodies. In addition, when surface treatment of a magnetic material is performed in an aqueous phase, fatty acids are likely to gather near the surface of the magnetic material, and the hydroxyl groups and carboxyl groups on the surface of the magnetic material form hydrogen bonds, so that the fatty acids are uniformly attached. Can do. Thereby, the dispersibility of the release agent in the toner particles can be improved, and a magnetic toner in which the release agent is more uniformly dispersed around the magnetic body can be manufactured. The toner particles stored in an environment of 40 ° C. for 30 days have an affinity between the fatty acid uniformly attached to the magnetic material and the release agent, so that the wettability at 50 ° C. is 55% by volume or less. Since chargeability after severe storage can be stabilized, there is no change in line dot reproducibility. Further, since the release agent can be finely dispersed from the center of the toner to the periphery of the magnetic body by the affinity between the magnetic body and the release agent, it is possible to increase the bleeding rate of the release agent during fixing.

  On the other hand, in the conventional production method in which fatty acid is attached to the surface of a magnetic material, the fatty acid cannot be coated with uniform orientation on the magnetic material. For this reason, the intermolecular force acting as an interaction between the magnetic substance and the release agent is weakened. Since the interaction between the magnetic material and the release agent is weak, the release agent and the magnetic material have structures separated at different locations. For this reason, even in a toner to which a large amount of a release agent is added, heat applied during fixing is absorbed by the magnetic material, and the rate of seeping of the release agent during fixing becomes slow. Furthermore, when the number of parts added to the mold release agent is increased, the amount of the mold release agent exuded in a high-temperature and high-humidity environment increases, so that the storage stability is deteriorated.

  Next, the manufacturing method of the magnetic body by a fatty acid or a fatty acid metal salt is demonstrated.

  The magnetic material used in the toner of the present invention preferably has a volume average particle diameter (Dv) (D3 is a body area average particle diameter) of 0.10 μm or more and 0.40 μm or less. It is preferable that the volume average particle diameter (Dv) of the magnetic material is 0.10 μm or more and 0.40 μm or less because sufficient coloring power can be obtained and the dispersibility of the magnetic material can be improved and fogging can be reduced.

  The volume average particle diameter (Dv) of the magnetic material can be measured using a transmission electron microscope. Specifically, after sufficiently dispersing the toner particles to be observed in the epoxy resin, a cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days is obtained. The obtained cured product is used as a flaky sample by a microtome, and the particle diameters of 100 magnetic bodies in the field of view are measured with a transmission electron microscope (TEM) with a photograph with a magnification of 10,000 to 40,000 times. Then, the volume average particle diameter (Dv) is calculated based on the equivalent diameter of a circle equal to the projected area of the magnetic material. It is also possible to measure the particle size with an image analyzer.

  The magnetic material used in the toner of the present invention is preferably magnetic iron oxide. Magnetic iron oxide can be produced, for example, by the following method. An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equivalent to or greater than the iron component to the ferrous salt aqueous solution. Air was blown in while maintaining the pH of the prepared aqueous solution at 7.0 or higher, and ferrous hydroxide was oxidized while heating the aqueous solution to 70 ° C. or higher, and seed crystals serving as the core of the magnetic iron oxide particles were formed. First generate.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. The pH of the liquid is maintained at 5.0 or higher and 10.0 or lower, and the reaction of ferrous hydroxide proceeds while blowing air, and magnetic iron oxide particles are grown with the seed crystal as a core. At this time, it is possible to control the shape and magnetic characteristics of the magnetic material by selecting an arbitrary pH, reaction temperature, and stirring conditions. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 5.0. A magnetic material can be obtained by filtering, washing, and drying the magnetic material thus obtained by a conventional method.

  A conventionally known magnetic material is used as the magnetic material that can be used in the present invention. Examples of magnetic materials contained in the magnetic toner include iron oxides such as magnetite, maghemite, and ferrite, and iron oxides including other metal oxides; metals such as Fe, Co, Ni, or these metals and Al, Co, Cu , Pb, Mg, Ni, Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, alloys with metals such as Se, Ti, W, and V; and mixtures thereof.

The magnetic material used in the toner of the present invention is mainly composed of magnetic iron oxides such as triiron tetroxide and γ-iron oxide, and phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, silicon, etc. These elements may be included. These magnetic materials preferably have a BET specific surface area of 2 to 30 m ² / g, more preferably 3 to 28 m ² / g, by a nitrogen adsorption method. Further, those having a Mohs hardness of 5 to 7 are preferred. The shape of the magnetic powder includes polyhedron, octahedron, hexahedron, spherical shape, needle shape, scale shape, etc., but those having low anisotropy such as polyhedron, octahedron, hexahedron, spherical shape, etc. It is preferable in terms of enhancement.

  The magnetic material preferably has a volume average particle size of 0.10 μm or more and 0.40 μm or less. In general, the smaller the particle size of the magnetic material, the higher the coloring power, but the magnetic material tends to aggregate, and the uniform dispersibility of the magnetic material in the toner is inferior. In addition, when the volume average particle size is less than 0.10 μm, the magnetic powder itself becomes reddish black, so that it becomes a reddish conspicuous image particularly in a halftone image, which is not preferable because it is not a high-quality image. . On the other hand, when the volume average particle diameter exceeds 0.40 μm, the coloring power of the toner is insufficient, and in the suspension polymerization method (described later), which is a preferable method for producing the toner of the present invention, uniform dispersion becomes difficult.

  As the fatty acid that can be used in the present invention, fatty acids having 6 to 50 carbon atoms can be suitably used, and among them, 12 to 24 carbon atoms are particularly preferable. For example, larlylic acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid.

  Examples of fatty acid metal salts include salts of the above fatty acids with Li, Mg, Al, Ca, Sr, Ba, Sn, Pb, Zn, and the like. The treatment amount of the fatty acid and the fatty acid metal salt is preferably 1.5% by mass or more and 5.0% by mass or less with respect to 100% by mass of the magnetic substance.

  Next, the fatty acid and the fatty acid salt were dropped into an aqueous solution in which the untreated magnetic material was uniformly dispersed, and then the pH was made alkaline. The pH is preferably 8 or more and 10 or less. While stirring sufficiently, an aqueous calcium salt solution is gradually dropped to adsorb fatty acids on the surface of the magnetic material. The obtained slurry was filtered, dehydrated at 100 ° C. or higher and 150 ° C. or lower, dried and crushed to obtain a fatty acid-treated magnetic material.

  In the present invention, the fatty acid part of the fatty acid or fatty acid metal salt is preferably stearic acid. Since the surface of the magnetic material can be uniformly treated with stearic acid, the magnetic material is uniformly dispersed, and the release agent is ideally dispersed around the magnetic material, thereby improving the fixing start temperature in a low temperature and low humidity environment. Since sodium stearate can be stably present in the aqueous phase, stearic acid can be bonded to the surface of the magnetic material with orientation. This enhances the affinity between the release agent in the toner and the treated magnetic material.

  In the present invention, the total amount of volatile components detected after the peak detection time of a hydrocarbon having 16 carbon atoms when the ester wax is measured by heating adsorption / GC / MS analysis at a heating temperature of 200 ° C. and a heating time of 10 minutes. (A) is preferably 1500 ppm or less (in terms of hexadecane). By reducing the impurities in the ester wax, the causative substance of member contamination does not come out of the toner at the time of fixing, and contamination of the fixing roller can be prevented. As a result, the toner with good image quality can be provided since no dullness or the like due to defective charging is generated.

  Furthermore, according to the toner production in the aqueous medium suitable for the present invention, the polar component and the hydrophobic component derived from the fatty acid on the surface of the magnetic substance in the aqueous medium each increase the number of contact with the release agent. For this reason, the intermolecular force is strengthened in the polar component and the hydrophobic component on the surface of the magnetic material whose number of contact with the release agent is increased. Further, when the ester wax is used, the ester wax is excellent in plasticity, so that the release agent present in the toner is easily pushed out and the release property is improved.

  The materials that can be used in the magnetic toner of the present invention are described below.

  The toner of the present invention contains a magnetic material, and the amount of the magnetic material is preferably 20 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the binder resin. By adjusting the addition amount of the magnetic material to 20 parts by mass or more and 150 parts by mass or less, the coloring power is good, the fog is small, and good fixability can be obtained.

  Note that the content of the magnetic substance in the toner can be measured using a thermal analyzer, TGA7, manufactured by PerkinElmer. In the measurement method, the toner is heated from normal temperature to 900 ° C. at a temperature rising rate of 25 ° C./min in a nitrogen atmosphere, and the weight loss from 100 ° C. to 750 ° C. is defined as the binder resin amount, and the remaining mass is approximated. The amount of magnetic material.

  Although the magnetic toner of the present invention contains a release agent, aliphatic hydrocarbon waxes and ester waxes can be suitably used, and among these, ester waxes are preferable. Since ester wax has a structure similar to that of a magnetic material treated with a fatty acid or a fatty acid metal salt, it exhibits high affinity. Accordingly, the release agent is finely dispersed in the magnetic toner and the deformation of the magnetic toner is promoted, so that the magnetic toner according to the present invention can have very high plasticity.

  As the ester wax, monofunctional and bifunctional ester waxes are suitable. Specific examples of the ester wax include stearyl stearate, behenyl behenate, palmitic acid palmitate, and the like. Examples of the synthetic ester wax include a monoester wax synthesized from a long-chain linear saturated fatty acid and a long-chain linear saturated alcohol. The long-chain linear saturated fatty acid is represented by the general formula CnH2n + 1COOH, and those having n = 5 or more and 28 or less are preferably used. The long-chain straight-chain saturated alcohol is preferably represented by CnH2n + 1OH and n = 5 to 28. That is, since the linear ester wax has no side chain, the mobility in the binder is large, and when it is deformed at the time of fixing, the ester wax slips through the binder and easily oozes out on the toner surface.

  However, when the ester wax is tetrafunctional or higher, a supramolecule is formed because it has a bulky structure in which a plurality of side chains are bonded to the main chain. As a result, movement in the binder is hindered, so that the releasability at the time of fixing is deteriorated.

  Specific examples of long-chain linear saturated fatty acids include capric acid, undecyl acid, lauric acid, tridecyl acid, myristic acid, palmitic acid, pentadecylic acid, heptadecanoic acid, tetradecanoic acid, stearic acid, nonadecanoic acid, aramonic acid, Examples include behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, and melicic acid.

  On the other hand, specific examples of the long-chain linear saturated alcohol include amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, penta Examples include decyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, ceryl alcohol, and heptadecanool.

  Examples of the ester wax having two or more ester bonds per molecule include, for example, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, Examples include 18-octadecanediol-bis-stearate, polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, and the like.

  Examples of natural ester waxes include candelilla wax, carnauba wax, rice wax, wax, jojoba oil, honey lauroline, castor wax, montan wax, and derivatives thereof.

  Examples of other modified waxes include polyalkanoic acid amides (ethylenediamine dibehenylamide, etc.), polyalkylamides (trimellitic acid tristearylamide, etc.), dialkyl ketones (distearyl ketone), and the like.

  In the present invention, the content of the release agent in the magnetic toner is preferably 5.0% by mass or more and 20.0% by mass or less, more preferably 5.0% by mass or more and 15.0% by mass or less. . When the amount is less than 5.0% by mass, the releasability of the toner cannot be maintained. When the amount is more than 20.0% by mass, the wax is easily exposed on the toner surface, and the heat-resistant storage stability is lowered.

  The weight average particle diameter (D4) of the toner of the present invention is preferably 3.0 μm or more and 12.0 μm or less, and more preferably 4.0 μm or more and 10.0 μm or less. When the weight average particle diameter (D4) is 3.0 μm or more and 12.0 μm or less, good fluidity can be obtained and development can be performed faithfully to the latent image. For this reason, a good image excellent in dot reproducibility can be obtained.

  The toner of the present invention preferably has an average circularity of 0.960 or more, and more preferably a mode circularity of 0.97 or more. When the average circularity of the toner is 0.960 or more, the toner has a spherical shape or a shape close to it, and it is easy to obtain a uniform triboelectric chargeability with excellent fluidity. For this reason, it is preferable because high developability is easily maintained even in the latter half of the durability.

  The glass transition temperature (Tg) of the toner of the present invention is preferably 40.0 ° C. or higher and 70.0 ° C. or lower. When the glass transition temperature is 40.0 ° C. or higher and 70.0 ° C. or lower, storage stability and durability can be improved while maintaining good fixability.

  As the binder resin used in the toner of the present invention, all known resins can be used, but styrene-acrylic resins are particularly preferable in terms of development characteristics, fixing properties, durability, and the like.

  In the toner of the present invention, a charge control agent may be blended as necessary to improve charging characteristics. As the charge control agent, a known one can be used, but a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Further, when the toner is produced using a polymerization method as described later, a charge control agent having a low polymerization inhibitory property and substantially free of soluble matter in an aqueous dispersion medium is particularly preferable. Among the charge control agents, specific examples of negative charge control agents include metal compounds of aromatic carboxylic acids such as salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, dicarboxylic acid, azo dyes or metal salts of azo pigments or Examples thereof include a metal complex, a polymer compound having a sulfonic acid or carboxylic acid group in the side chain, a boron compound, a urea compound, a silicon compound, and a calixarene.

  As a method for adding a charge control agent to the toner, a method of adding the charge control agent to the inside of the toner particles, and in the case of producing the toner by suspension polymerization, the charge control agent in the polymerizable monomer composition before granulation. A method of adding is generally used. Also, during the polymerization by forming oil droplets in water, or after polymerization, seed polymerization is carried out by adding a polymerizable monomer in which the charge control agent is dissolved and suspended, and the toner surface is made uniform. It is also possible to cover. In the case where an organometallic compound is used as the charge control agent, it is also possible to introduce the compound by adding these compounds to the toner particles, and applying a shear and mixing and stirring.

  The amount of these charge control agents used is determined by the toner production method including the type of binder resin, the presence or absence of other additives, and the dispersion method, and is not uniquely limited. However, when added internally to the toner particles, it is preferably 0.1 parts by weight or more and 10.0 parts by weight or less, more preferably 0.1 parts by weight or more and 5.0 parts by weight or less with respect to 100 parts by weight of the binder resin. Used in a range. In addition, when externally added to the toner particles, the amount is preferably 0.005 parts by mass or more and 1.000 parts by mass or less, more preferably 0.01 parts by mass or more and 0.30 parts by mass or less with respect to 100 parts by mass of the toner particles. .

  Next, a method for producing the toner of the present invention will be described.

  First, in the case of producing by a pulverization method, for example, components necessary as a toner such as a binder resin, a magnetic material, and a release agent and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill. Thereafter, the toner material is dispersed or dissolved by using a heat kneader such as a heating roll, a kneader, or an extruder to disperse or dissolve the toner material, and after cooling and solidification, pulverization, and surface treatment as necessary to obtain toner particles. be able to. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

  The pulverization step can be performed by a method using a known pulverizer such as a mechanical impact type or a jet type. Further, in order to obtain a toner having a preferable circularity of the present invention, it is preferable to further heat and pulverize, or to perform a process of applying a mechanical impact as an auxiliary. Further, a hot water bath method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water, a method of passing in a hot air stream, or the like may be used.

  Examples of means for applying a mechanical impact force include a method using a mechanical impact pulverizer such as a kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industry. Further, there is a method in which a mechanical impact force is applied to the toner by a force such as a compressive force or a frictional force, as in a device such as a mechano-fusion system manufactured by Hosokawa Micron Corporation or a hybridization system manufactured by Nara Machinery Co., Ltd.

  The toner of the present invention can be produced by a pulverization method as described above, but the toner particles obtained by this pulverization method are generally indefinite. For this reason, it is difficult to obtain uniform chargeability, and it is difficult to satisfy that the 25 ° C. wettability Wa, which is an essential requirement of the present invention, is 30% by volume or more and 50% by volume or less.

  Therefore, the toner particles of the present invention are preferably produced in an aqueous medium such as a dispersion polymerization method, an association aggregation method, a dissolution suspension method, a suspension polymerization method, and the suspension polymerization method is more preferable.

  In the suspension polymerization method, a polymerizable monomer and a magnetic substance (further, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly dissolved or dispersed to form a polymerizable monomer. A composition is obtained. Thereafter, the polymerizable monomer composition is dispersed in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer, and a polymerization reaction is simultaneously performed to obtain a toner having a desired particle size. To get. The toner obtained by this suspension polymerization method (hereinafter also referred to as “polymerized toner”) is preferable because the shape of individual toner particles is almost spherical, and the charge amount distribution is relatively uniform.

  In the production of the polymerized toner according to the present invention, examples of the polymerizable monomer constituting the polymerizable monomer composition include the following.

  Examples of the polymerizable monomer include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene, methyl acrylate, ethyl acrylate, Acrylate esters such as n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate , Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, Methacrylic acid dimethyl aminoethyl, methacrylic acid esters such as diethylaminoethyl methacrylate and other acrylonitrile, methacrylonitrile, and the like monomers acrylamide. These monomers can be used alone or in combination. Among the above-mentioned monomers, styrene or a styrene derivative is preferably used alone or mixed with other monomers from the viewpoint of developing characteristics and durability of the toner.

  The polymerization initiator used in the production of the toner according to the present invention by polymerization is preferably one having a half-life of 0.5 hours or more and 30.0 hours or less during the polymerization reaction. Moreover, it is preferable that the addition amount of a polymerization initiator is 0.5 to 20.0 mass parts with respect to 100 mass parts of polymerizable monomers.

  Specific examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1- Carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo or isoazo polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxide Peroxide polymerization initiators such as oxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, t-butylperoxy 2-ethylhexanoate, t-butylperoxypivalate, etc. Can be mentioned.

  When the toner of the present invention is produced by a polymerization method, a crosslinking agent may be added. A preferable addition amount is 0.01 parts by mass or more and 10.00 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer. It is. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate, divinyl A divinyl compound such as aniline, divinyl ether, divinyl sulfide, divinyl sulfone and the like and a compound having three or more vinyl groups are used alone or as a mixture of two or more.

  In the method for producing the toner of the present invention by a polymerization method, generally, the above-described toner composition or the like is added as appropriate, and the polymerizable single particle is uniformly dissolved or dispersed by a disperser such as a homogenizer, a ball mill, or an ultrasonic disperser. The meter composition is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a disperser such as a high-speed stirrer or an ultrasonic disperser to obtain a desired toner particle size all at once. The polymerization initiator may be added at the same time as other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Also, a polymerization initiator dissolved in a polymerizable monomer or solvent can be added immediately after granulation and before starting the polymerization reaction.

  After granulation, stirring may be performed using a normal stirrer to such an extent that the particle state is maintained and particle floating and sedimentation are prevented.

  When the toner of the present invention is produced, known surfactants, organic dispersants and inorganic dispersants can be used as the dispersion stabilizer. In particular, inorganic dispersants are less likely to produce harmful ultrafine powders, and because of their steric hindrance, dispersion stability is obtained, so even if the reaction temperature is changed, stability is not easily lost, and washing is easy and does not adversely affect the toner. Therefore, it can be preferably used. Examples of such inorganic dispersants include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, phosphate polyvalent metal salts such as hydroxyapatite, carbonates such as calcium carbonate and magnesium carbonate, calcium metasuccinate, calcium sulfate, Examples thereof include inorganic salts such as barium sulfate and inorganic compounds such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide.

  These inorganic dispersants are preferably used in an amount of 0.20 parts by mass or more and 20.00 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer. Moreover, the said dispersion stabilizer may be used independently and may use multiple types together. Furthermore, you may use together 0.0001 mass part or more and 0.1000 mass part or less surfactant with respect to 100 mass parts of polymerizable monomers.

  In the step of polymerizing the polymerizable monomer, the polymerization temperature is set to 40 ° C or higher, and generally 50 ° C to 90 ° C.

  After the polymerization of the polymerizable monomer is completed, the obtained polymer particles are filtered, washed and dried by a known method to obtain toner particles. The toner of the present invention can be obtained by mixing the toner particles with inorganic fine powder as will be described later as necessary and adhering them to the surface of the toner particles. It is also possible to insert a classification step in the manufacturing process (before mixing the inorganic fine powder) to cut coarse powder and fine powder contained in the toner particles.

  The toner of the present invention has an inorganic fine powder, and the number average primary particle size (D1) of the inorganic fine powder is preferably 4 nm or more and 80 nm or less, more preferably 6 nm or more and 40 nm or less. When the number average primary particle size (D1) of the inorganic fine powder is 4 nm or more and 80 nm or less, the fluidity of the toner is excellent, and uniform chargeability can be obtained, and a uniform image can be obtained even in long-term use. Can be obtained. In the present invention, the number average primary particle size (D1) of the inorganic fine powder is measured using a photograph of the toner magnified by a scanning electron microscope.

  Silica, titanium oxide, alumina, etc. can be used as the inorganic fine powder used in the present invention. As the fine silica powder, for example, both a so-called dry method produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass or the like can be used. is there.

  In the present invention, the addition amount of the inorganic fine powder is preferably 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles. The addition amount of the inorganic fine powder is preferably in the above range since the toner can be given good fluidity and the fixing property is not hindered. The content of the inorganic fine powder can be quantified using a calibration curve prepared from a standard sample using fluorescent X-ray analysis.

  Next, an example of an image forming apparatus that can suitably use the toner of the present invention will be specifically described with reference to FIG. In FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier (hereinafter also referred to as a photoconductor), which includes a charging roller 117, a developing device 140 having a toner carrier 102, a transfer charging roller 114, a cleaner 116, and a register roller. 124 etc. are provided. The electrostatic latent image carrier 100 is charged to, for example, −600 V by the charging roller 117 (applied voltages are, for example, an AC voltage of 1.85 kVpp and a DC voltage of −620 Vdc). Then, exposure is performed by irradiating the electrostatic latent image carrier 100 with the laser beam 123 by the laser generator 121, and an electrostatic latent image corresponding to the target image is formed. The electrostatic latent image on the electrostatic latent image carrier 100 is developed with a one-component toner by the developing device 140 to obtain a toner image, and the toner image is transferred in contact with the electrostatic latent image carrier via a transfer material. The image is transferred onto the transfer material by the roller 114. The transfer material on which the toner image is placed is conveyed to the fixing device 126 by the conveying belt 125 or the like and fixed on the transfer material. In addition, the toner remaining on the electrostatic latent image carrier is partially cleaned by the cleaner 116.

  Next, an external heating type image heating apparatus (hereinafter also referred to as a fixing roller) used in the fixing test of the present invention will be described.

  In the image heating device, the heating member that melts and fixes the unfixed toner image on the recording material by heat does not have a heat source inside, and an external heating and fixing device that uses heat storage received from the heating means from the surface for melting the toner is preferable. Used (see FIG. 3 described later). This is because the inside has an elastic layer having a high heat insulating property, so that heat loss is less when heating from the outside.

  As shown in FIG. 2, the image heating member 30 is formed with a low thermal conductivity elastic layer (hereinafter referred to as an elastic layer) 32 having a low thermal conductivity and elasticity on the outer periphery of the cored bar 31, and the outer side thereof. In addition, the heat storage layer 33 is formed.

  The core metal 31 of the image heating member is formed of, for example, a metal material such as aluminum, iron, or SUM material, or another rigid material such as ceramic. Since the core 31 is thermally insulated from the surface of the fixing roller by the elastic layer 32, it may have low thermal conductivity and low heat capacity. The form may be a hollow cylinder.

  The elastic layer 32 formed on the outer periphery of the metal core 31 is a rubber layer having a low thermal conductivity, and the thermal conductivity is adjusted so as to be smaller than that of the heat storage layer 33. It is preferable that the elastic layer has a thermal conductivity of 0.15 W / mK or less because the amount of heat of the heat storage layer is difficult to escape to the cored bar and there is no loss of the amount of heat.

  The thickness of the elastic layer 32 is not particularly limited, but is 1.0 mm or more and 5.0 mm or less in order to form the fixing roller 30 having an effective heat insulating property and a heat capacity that is not too large and having a small diameter. Is preferably 2.0 mm or more and 4.0 mm or less.

  From the viewpoint of durability and heat insulating properties, the elastic layer is fired after forming a compound in which a hollow filler is blended with an organopolysiloxane composition, or a compound in which a water-absorbing polymer and water are blended in an organopolysiloxane composition. Those formed by curing are preferred.

  Next, the heat storage layer 33 formed on the outer periphery of the elastic layer 32 will be described. The heat storage layer 33 is preferably a solid rubber layer in which a layer in which a powdery heat conductive filler (hereinafter, also simply referred to as “filler”) is mixed with, for example, silicone rubber or fluorine rubber is formed on the elastic layer 32. Can be cited as a form. It is preferable for the heat storage layer to have the above configuration because the amount of heat applied to the heat storage layer via the release layer diffuses quickly throughout the heat storage layer.

  It is important that the heat storage layer has a higher thermal conductivity than the elastic layer 32. Preferably, the thermal conductivity is higher than that of general solid rubber, and is preferably 0.30 W / m · K or more.

  By making the thermal conductivity of the internal heat insulating layer lower than the thermal conductivity of the heat storage layer, the heat transferred from the surface of the fixing roller is unevenly distributed in the heat storage layer near the surface, and is easily maintained. Further, by increasing the thermal conductivity of the heat storage layer, heat can be absorbed and released in the heat storage layer quickly.

  The thickness of the heat storage layer 33 is preferably 50.0 μm or more and 500.0 μm or less. When the thickness of the heat storage layer 33 is 50.0 μm or more, it becomes easy to uniformly disperse the filler, and it becomes easy to obtain a stable heat capacity and thermal conductivity. Therefore, the amount of heat applied to the toner on the recording material tends to be uniform. Further, when the thickness of the heat storage layer 33 is 500.0 μm or less, it becomes easy to control the dispersibility of the filler in the fixing roller, so that it is easy to quickly absorb and release heat in the heat storage layer.

  It is also preferable that the heat conductive filler is contained in an amount of 7 to 60 parts by mass with respect to 100 parts by mass of the rubber forming the heat storage layer. When the heat conductive filler is 7 parts by mass or more, the heat storage layer tends to have a sufficient heat capacity, and the low-temperature fixability is easily improved. Further, when the heat conductive filler is 60 parts by mass or less, the hardness of the surface of the fixing roller tends to be in an appropriate range, so that the adhesion with the recording material is easily improved.

  The heat storage layer 33 is formed by the following method, for example. In particular, a solid rubber layer in which a layer obtained by mixing 7 parts by mass or more and 60 parts by mass of a powdered heat conductive filler in silicone rubber or fluororubber is formed on the elastic layer 32 is preferable.

  Any method can be used as a method for manufacturing the heat storage layer. For example, methods such as dipping coating, spray coating, and ring coating in which a liquid resin is coated and formed using a cylindrical coating head around a cylindrical core metal. In particular, ring coating can be preferably used because the heat storage layer can be uniformly applied.

  A thermal storage layer contains the heat conductive filler which is an Al and / or Zn compound at least. As the heat conductive filler, for example, powdery fillers such as alumina, zinc oxide, aluminum nitride, zinc nitride, metal aluminum, metal zinc, aluminum-containing alloy, and zinc-containing alloy are preferably used.

  Next, a method for measuring each physical property related to the magnetic toner of the present invention will be described.

<Evaluation of wettability>
The 25 ° C. wettability, 50 ° C. wettability and 70 ° C. wettability of the magnetic toner particles were measured using a methanol dropping transmittance curve. Specifically, as the measuring device, for example, a powder wettability tester WET-100P manufactured by Reska Co., Ltd. may be mentioned, and specific measuring operations may include the methods exemplified below.

  First, 70 ml of a hydrated methanol solution composed of 30% by volume of methanol and 70% by volume of water is placed in a flask, and dispersed for 5 minutes with an ultrasonic disperser in order to remove bubbles and the like in the measurement sample. A sample liquid for measuring the hydrophobic property of the magnetic toner is prepared by accurately weighing and adding 0.50 g of magnetic toner particles as a specimen. In the case of 25 ° C. wettability, the dried magnetic toner particles were used as they were. On the other hand, in the case of 50 ° C. wettability and 70 ° C. wettability, a product in which magnetic toner particles were allowed to stand for 6 hours in a thermostat set to 50 ° C. and 70 ° C. was used.

  Next, while stirring the sample solution for measurement at a speed of 6.67 m / s, methanol was added at 1.3 ml / min. Are continuously added at a dropping rate of 780 nm, the transmittance is measured with light having a wavelength of 780 nm, a methanol dropping transmittance curve is prepared, and the methanol concentration at which the transmittance is 50% is measured.

  In this measurement, the flask used was a circle having a diameter of 5 cm and a glass made of 1.75 mm, and the magnetic stirrer was a spindle having a length of 25 mm and a maximum diameter of 8 mm and was coated with a fluororesin. Use things.

<Measurement of Wax Volatile Component Concentration Using Heat Desorption Device>
The volatile component concentration of the wax in the present invention is measured by the following method.

The following measuring devices are used as measuring devices.
Thermal desorption device: TurboMatrixATD (manufactured by PerkinElmer)
GC / MS: TRACE DSQ (manufactured by Thermo Fisher Scientific)

(Production of glass tube with internal standard)
A glass tube for a heat desorption apparatus in which 10 mg of TenaxTA adsorbent is sandwiched between glass wools is prepared in advance, and prepared by performing conditioning at 300 ° C. for 3 hours in a state of flowing an inert atmosphere gas. Thereafter, 5 μL of a 100 ppm methanol solution of deuterated hexadecane (hexadecane D34) is adsorbed on TenaxTA to obtain a glass tube containing an internal standard.

(Measurement of mold release agent)
About 1 mg of the release agent is wrapped in aluminum foil previously baked out at 300 ° C., and put in a special tube prepared in (Preparation of glass tube with internal standard). The sample is covered with a fluororesin cap for a heat desorption apparatus and set in the apparatus.

This sample is measured under the following conditions, and the total peak area of the internal standard peak and the peak after deuterated hexadecane is calculated.
・ Heat desorption equipment tube temperature: 200 ℃
Transfer temperature: 300 ° C
Valve temperature: 300 ° C
Column pressure: 150 kPa
Inlet split: 25 ml / min.
Outlet split: 10 ml / min.
Secondary adsorption tube material: TenaxTA
Holding time: 10 min.
Secondary adsorption tube temperature during desorption: -30 ° C
Secondary adsorption tube desorption temperature: 300 ° C
GC / MS condition column: Ultra alloy (metal column) UT-5 (inner diameter 0.25 mm, liquid phase 0.25 μm, length 30 m)
Column heating conditions: 60 ° C. (3 min), 350 ° C. (20.0 ° C./min), 350 ° C. (10 min)

  The transfer line of the heat desorption apparatus and the GC column are directly connected, and the GC inlet is not used.

(analysis)
Of the peaks obtained by the above operation, all peaks after the retention time of deuterated hexadecane, which is an internal standard, are integrated, the total value of all peaks is calculated, and the volatile component concentration of wax is calculated from the following formula. At this time, care should be taken not to add a noise peak or the like different from the peak to the integrated value.
Volatile component concentration of wax (ppm) = (A1 / B1 × 0.0005 × 0.77) / C1 × 1000000
A1 ... Total peak area after deuterated hexadecane B1 ... Peak area C1 of deuterated hexadecane (internal standard) ... Weight of weighed wax (mg)

  Hereinafter, the present invention will be described more specifically with reference to production examples and examples. “Part” is based on mass unless otherwise specified.

  First, a method for producing a magnetic material will be described in detail.

<Manufacture of magnetic body 1>
In a ferrous sulfate aqueous solution, 1.0 equivalent or more and 1.1 equivalent or less of caustic soda solution with respect to iron element, and 1.5 mass% sodium silicate in terms of silicon element with respect to iron element are mixed, and water An aqueous solution containing ferrous oxide was prepared.

  While maintaining the aqueous solution at pH 9.0, air was blown in, and an oxidation reaction was performed at 80 ° C. or higher and 90 ° C. or lower to prepare a slurry liquid for generating seed crystals.

  Subsequently, the ferrous sulfate aqueous solution was added to this slurry liquid so that it might become 0.9 equivalent or more and 1.2 equivalent or less with respect to the original alkali amount (sodium component of caustic soda). Thereafter, the slurry liquid was maintained at pH 8.0, and an oxidation reaction was promoted while air was blown to obtain a slurry liquid containing magnetic iron oxide. The slurry was filtered and washed, and then the water-containing slurry liquid was once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample was re-dispersed in another aqueous medium without drying, and then methanol was added to 100 parts of magnetic iron oxide (the amount of magnetic iron oxide was calculated by subtracting the water content from the water-containing sample). 25.0 parts was added. Then, the temperature of the redispersed liquid was adjusted to 40 ° C., the pH was adjusted to 4.3, and sufficiently stirred. Further, 2.5 parts of 100 parts of magnetic iron oxide was added to the aqueous sodium stearate solution to adjust the pH to 8.0. Thereafter, an aqueous calcium salt solution was dropped to adsorb calcium stearate on the surface of the magnetic material. The obtained slurry was filtered with a filter press, washed with water, dehydrated and dried at 135 ° C. for 1 hour to obtain a treated magnetic body 1. Thereafter, it was found by ESCA that the amount of stearic acid deposited on the surface of the magnetic material was 4.0% by mass compared to the magnetic material.

  Hereinafter, treated magnetic bodies 2 to 11 were obtained by controlling the type and amount of fatty acid or fatty acid metal salt as shown in Table 1.

<Manufacture of magnetic body 12>
An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide to the ferrous salt aqueous solution in an amount equivalent to or greater than the iron component. While maintaining the prepared aqueous solution at pH 7 or higher (preferably pH 8 to 14), air was blown in, and the aqueous solution was heated to 70 ° C. or higher to oxidize ferrous hydroxide. First, a seed crystal is formed.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. While maintaining the pH of the solution at 6 to 14, the reaction of ferrous hydroxide is promoted while blowing air, and the magnetic iron oxide powder is grown around the seed crystal. At this time, it is possible to control the shape of the magnetic powder by selecting an arbitrary pH. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 6.

  When the surface treatment of the obtained magnetic iron oxide is performed, it is performed as follows. When the surface treatment is performed dry after the oxidation reaction, the magnetic powder that has been washed, filtered and dried is treated with a coupling agent or a low softening point material. After the surface treatment with the coupling agent in this manner, the surface of the magnetic fine particles is treated with sodium stearate using an apparatus capable of applying shear. As an apparatus to process, the apparatus which can perform a shear, a spatula, and compression simultaneously is preferable, and the wheel-type kneader was used. A treated magnetic body 12 was obtained by adding 6 parts by mass of sodium stearate to 100 parts by mass of magnetic iron oxide.

<Manufacture of magnetic body 13>
An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide to the ferrous salt aqueous solution in an amount equivalent to or greater than the iron component. While maintaining the prepared aqueous solution at pH 7 or higher (preferably pH 8 to 14), air was blown in, and the aqueous solution was heated to 70 ° C. or higher to oxidize ferrous hydroxide. First, a seed crystal is formed.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. While maintaining the pH of the solution at 6 to 14, the reaction of ferrous hydroxide is promoted while blowing air, and the magnetic iron oxide powder is grown around the seed crystal. At this time, it is possible to control the shape of the magnetic powder by selecting an arbitrary pH. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 6.

  As a method of treating the surface of a magnetic material with a fatty acid and / or a derivative thereof, 2 parts by mass of sodium palmitate is added to 100 parts by mass of magnetic iron oxide, and both are heated at 100 ° C. or higher for about 5 to 30 minutes. What is necessary is just to mix, The mixture of a magnetic body and a surface treating agent was put into a Henschel mixer etc., and was stirred for about 5 to 30 minutes. According to this method, heat generation occurs to about 100 to 150 ° C. by stirring, and the treatment agent is uniformly coated on the surface of the magnetic body. The processed magnetic body 13 was obtained by the above method.

<Manufacture of magnetic body 14>
In a ferrous sulfate aqueous solution, 1.0 equivalent or more and 1.1 equivalent or less of caustic soda solution with respect to iron element, and 1.5 mass% sodium silicate in terms of silicon element with respect to iron element are mixed, and water An aqueous solution containing ferrous oxide was prepared.

  While maintaining the aqueous solution at pH 9.0, air was blown in, and an oxidation reaction was performed at 80 ° C. or higher and 90 ° C. or lower to prepare a slurry liquid for generating seed crystals.

  Subsequently, the ferrous sulfate aqueous solution was added to this slurry liquid so that it might become 0.9 equivalent or more and 1.2 equivalent or less with respect to the original alkali amount (sodium component of caustic soda). Thereafter, the slurry liquid was maintained at pH 8.0, and an oxidation reaction was promoted while air was blown to obtain a slurry liquid containing magnetic iron oxide. The slurry was filtered and washed, and then the water-containing slurry liquid was once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample was re-dispersed in another aqueous medium without drying, and then methanol was added as 100 parts by mass of magnetic iron oxide (the amount of magnetic iron oxide was calculated as a value obtained by subtracting the water content from the water-containing sample. ) 25.0 parts by mass. Then, the temperature of the redispersed liquid was adjusted to 40 ° C., the pH was adjusted to 4.3, and sufficiently stirred. Then, 2.0 parts by mass of n-hexyltrimethoxysilane was added to 100 parts by mass of magnetic iron oxide to perform hydrolysis. Thereafter, the pH of the dispersion was set to 8.0 to perform a condensation reaction, and a hydrophobic treatment was performed. The obtained hydrophobic magnetic material was washed, filtered, dried and crushed by a conventional method. The obtained magnetic body 14 had a volume average particle diameter of 0.20 μm and an SiH amount of 2%.

<Synthesis of polyester resin 1>
The following components were placed in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, and reacted for 10 hours while distilling off the water produced at 230 ° C. under a nitrogen stream.
Bisphenol A EO 2 mol adduct 350 parts Bisphenol A PO 2 mol adduct 326 parts terephthalic acid 278 parts Titanium-containing catalyst 1 2 parts Subsequently, the reaction is carried out under reduced pressure of 5 to 20 mmHg, and 180 when the acid value becomes 2 or less. After cooling to ° C., 62 parts of trimellitic anhydride was added, taken out after reaction for 2 hours under normal pressure sealing, cooled to room temperature, and then pulverized to obtain polyester resin 1. As a catalyst, a polyester resin having a weight average molecular weight (Mw) of 10300, a number average molecular weight (Mn) of 3700, and a Tg of 69 ° C. was obtained as various physical properties of the polyester resin 1 in addition to a titanium-containing catalyst.

  Next, details of the magnetic toner used in the examples will be described.

<Example 1: Production of magnetic toner 1>
450 parts of 0.1M Na ₃ PO ₄ aqueous solution is added to 720 parts of ion-exchanged water and heated to 60 ° C., and then 67.7 parts of 1.0M CaCl ₂ aqueous solution is added to contain a dispersion stabilizer. An aqueous medium was obtained.
・ Styrene 76.0 parts ・ n-Butyl acrylate 24.0 parts ・ Divinylbenzene 0.53 parts ・ Azo complex (T-77: Hodogaya Chemical Co., Ltd.) 1.0 part ・ Polyester resin 1 5.0 parts ・ Processed magnetism Body 1 90.0 parts The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.) to obtain a monomer composition. This monomer composition was heated to 60 ° C., and 15 parts of stearyl stearate was added and dissolved therein, and then 4.5 parts of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile). Was dissolved.

The monomer composition was put into the aqueous medium, and granulated by stirring at 12,000 rpm for 10 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) in an N ₂ atmosphere at 60 ° C. Thereafter, the reaction was carried out at 70 ° C. for 5 hours while stirring with a paddle stirring blade, then the temperature was raised to 80 ° C. and the mixture was stirred as it was for 2 hours. After completion of the reaction, the suspension was cooled, hydrochloric acid was added to adjust the pH to 0.8, and the mixture was stirred for 2 hours, filtered and dried to obtain magnetic toner particles 1.

100 parts of the magnetic toner particles 1 and silica having a number average particle diameter of 12 nm are treated with hexamethyldisilazane and then with silicone oil, and a hydrophobic silica fine powder 1.0 having a BET value of 120 m ² / g after the treatment is obtained. Parts were mixed with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.) to obtain a magnetic toner 1 having a weight average particle diameter of 7.2 μm. Table 3 shows the physical properties of the magnetic toner 1.

<Examples 2 to 20: Production of magnetic toner 2 to magnetic toner 20>
The magnetic toner 1 was produced in the same manner as the magnetic toner 1 except that the treated magnetic material, the type of release agent, and the number of added parts were changed according to Table 2. The release agent used in Examples 19 and 20 was HNP9 (melting point: 74 ° C., manufactured by Nippon Seiki Co., Ltd.) as a paraffin wax. Table 3 shows the physical properties of the magnetic toners 2 to 20.

<Comparative Example 1: Production of magnetic toner 21>
In the production of the magnetic toner 1, the magnetic toner 21 was prepared in the same manner as the production of the magnetic toner 1 except that the treated magnetic body 1 was changed to the treated magnetic body 9 and stearyl stearate was changed to carnauba wax (melting point: 72 ° C.). Obtained. Table 3 shows the physical properties of the magnetic toner 21.

<Comparative Example 2: Production of magnetic toner 22>
In the production example of the magnetic toner 1, the magnetic toner 22 was changed in the same manner as the production of the magnetic toner 1 except that the treated magnetic body 1 was changed to the treated magnetic body 11 and stearyl stearate was changed to paraffin wax (melting point 72 ° C.). Obtained. Table 3 shows the physical properties of the magnetic toner 22.

<Comparative Example 3: Production of Magnetic Toner 23>
The magnetic toner 21 is manufactured by a pulverization method.

Binder resin 1
Propoxylated bisphenol A (2.2 mol adduct): 25.0 mol%
Ethoxylated bisphenol A (2.2 mol adduct): 25.0 mol%
・ Terephthalic acid: 32.0 mol%
-Trimellitic anhydride: 6.0 mol%
Adipic acid: 4.5 mol%
Acrylic acid: 4.5 mol%
・ Fumaric acid: 3.0 mol%
The polyester monomer was charged into a four-necked flask together with an esterification catalyst, and a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device, and a stirring device were attached and stirred at 135 ° C. in a nitrogen atmosphere. In the present production example, fumaric acid was added in portions at the early and late stages of the reaction in order to obtain a desired crosslinked structure in the present invention. A vinyl copolymer monomer (styrene: 83 mol% and 2-ethylhexyl acrylate: 15 mol%) and a mixture of 2 mol% of benzoyl peroxide as a polymerization initiator were dropped from the dropping funnel over 4 hours. Then, after reacting at 135 ° C. for 5 hours, the reaction temperature at the time of polycondensation was raised to 230 ° C. to perform a condensation polymerization reaction. After completion of the reaction, the reaction product was taken out from the container, cooled and pulverized to obtain a binder resin 1. The weight average molecular weight (Mw) was 62000 and the number average molecular weight (Mn) was 7950.

Polymer A
・ 20 parts of low density polyethylene (Mw 1400, Mn 850, maximum endothermic peak by DSC is 100 ° C.)
Styrene 64 parts, n-butyl acrylate 13.5 parts, acrylonitrile 2.5 parts were charged in an autoclave, and the inside of the system was replaced with N ₂ , and then maintained at 180 ° C. while stirring at elevated temperature. A polymer in which 50 parts of a 2% by mass t-butyl hydroperoxide xylene solution was continuously dropped into the system for 5 hours, and after cooling, the solvent was separated and removed, and the vinyl resin component reacted with the low-density polyethylene. A was obtained. When the molecular weight of the polymer A was measured, it was weight average molecular weight (Mw) 7000 and number average molecular weight (Mn) 3000.

・ Binder resin 1 100 parts ・ Polymer A 2 parts ・ Fischer-Tropsch wax (peak temperature of maximum endothermic peak 105 ° C.) 4 parts ・ Processed magnetic substance 9 95 parts ・ Monoazo iron compound (T77: manufactured by Hodogaya Chemical Co., Ltd.) 2 parts After mixing the above prescription with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), a biaxial kneader (PCM-30 type, manufactured by Ikekai Tekko Co., Ltd.) set at a temperature of 130 ° C. Kneaded. The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely crushed material was pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Further, classification was performed by a multi-division classifier utilizing the Coanda effect, and magnetic toner particles having a weight average particle diameter of 6.3 μm were obtained.

100 parts of the magnetic toner particles and silica having a number average particle diameter of 12 nm are treated with hexamethyldisilazane and then with silicone oil, and 1.0 part of hydrophobic silica fine powder having a BET value of 120 m ² / g after the treatment is obtained. The magnetic toner 23 was obtained by mixing with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.). Table 3 shows the physical properties of the magnetic toner 23.

<Comparative Example 4: Production of Magnetic Toner 24>
In the production of the magnetic toner 21, a magnetic toner 24 was obtained in the same manner as in the production of the magnetic toner 21 except that the number of added part of the release agent was changed from 4 parts to 16 parts. Table 3 shows the physical properties of the magnetic toner 24.

<Comparative Example 5: Production of magnetic toner 25>
In the production of the magnetic toner 1, the magnetic toner 25 was obtained in the same manner as the production of the magnetic toner 1 except that the treated magnetic body 1 was changed to the treated magnetic body 12 and stearyl stearate was changed to paraffin wax (melting point 72 ° C.). It was. Table 3 shows the physical properties of the magnetic toner 25.

<Comparative Example 6: Production of magnetic toner 26>
In the production of the magnetic toner 21, the magnetic toner 26 was obtained in the same manner as the production of the magnetic toner 21 except that the treated magnetic body 9 was changed to the treated magnetic body 13 and the number of added paraffin wax was changed from 4 parts to 20 parts. . Table 3 shows the physical properties of the magnetic toner 26.

<Comparative Example 7: Production of magnetic toner 27>
In the production of the magnetic toner 1, the magnetic toner 27 was obtained in the same manner as in the production of the magnetic toner 1 except that the treated magnetic body 1 was changed to the treated magnetic body 14. Table 3 shows the physical properties of the magnetic toner 27.

Rating:
The produced magnetic toners (Examples 1 to 20 and Comparative Examples 1 to 7) were evaluated as follows. The results are summarized in Table 3.

<Evaluation of fixing start temperature>
As the image forming apparatus, LBP-3410 (manufactured by Canon) was used, and the fixing device was changed to the one shown in FIG. 3 having the fixing roller 30 shown in FIG. The fixing device 7 is an external heating method in which a heat source is a plate-like heater 21. The configuration of the fixing roller is as follows.
Elastic layer: Thermal conductivity is 0.20 W / (m · K) or less High thermal conductivity layer: The thickness of the heat storage layer is 30 μm or more and 400 μm or less, and the heat capacity per unit area of the heat storage layer is C / S. 100 J / (m ² · K) ≦ C / S ≦ 600 J (m ² · K).

The above-mentioned LBP-3410 is used as an image for evaluating the fixing start temperature, and the amount of toner applied on the paper is 0.4 mg / mm on A4 paper EN-100 (manufactured by Canon) in a normal temperature and normal humidity environment (23 ° C./60%). The development contrast was adjusted to be cm ^2, and a solid unfixed image having a tip margin of 10 mm, a width of 200 mm, and a length of 20 mm was produced.

In a room temperature and normal humidity environment (23 ° C./60%), the fixing temperature was changed from 160 ° C. in increments of 5 ° C., and the unfixed image was passed through a fixing device to fix to 200 ° C. 5 cm from the rear edge of the fixed image, while applying a load of 4.9 kPa, rubbing 5 times with soft thin paper (for example, “Dasper”, manufactured by Ozu Sangyo Co., Ltd.), before and after rubbing The image density reduction rate ΔD (%) was calculated by the following equation. The image density was evaluated using a reflection densitometer 500 Series Spectrodensitometer manufactured by X-rite. The temperature at which ΔD (%) was less than 10% was determined as the fixing start temperature.
ΔD (%) = (Image density before rubbing−Image density after rubbing) × 100 / Image density before rubbing Further, in a low temperature and low humidity environment, apart from the room temperature and normal humidity environment (NN environment). (15 ° C / 10%; LL environment) was also evaluated.

(Evaluation criteria)
A: Fixing start temperature is 160 ° C. to 170 ° C., excellent fixability B: Fixing start temperature is 170 ° C. to 180 ° C. Good fixability C: Fixing start temperature is 180 ° C. to 190 ° C. Fixability D with no problem in practical use: Fixing start temperature is 190 ° C. or higher and inferior fixability

<Evaluation method of offset resistance>
With respect to the fixed image obtained in the evaluation of the fixing start temperature, it was evaluated whether or not a high temperature offset (a phenomenon in which the fixed image adhered to the fixing roller from the paper and the fixing roller rotated once and reattached to the paper) occurred.

  When the image density of the non-image portion showed a density of 0.03 times or more of the solid image density, an offset was generated. The image density was evaluated using a reflection densitometer 500 Series Spectrodensitometer manufactured by X-Rite.

(Evaluation criteria)
A: No low temperature offset occurred and excellent offset resistance B: Low temperature offset occurred at 160 ° C. Good offset resistance C: Low temperature offset occurred at 170 ° C. and 180 ° C. No offset resistance D: Low temperature offset occurs at 190 ° C or higher, resulting in poor offset resistance

<Development evaluation after severe storage of toner>
For severe storage of the toner, 200 g of toner was placed in a 500 mL plastic cup and left in a constant temperature bath at 40 ° C. (within ± 0.5 ° C.) for 30 days, and then an image was output. An LBP 3410 was used as the image forming apparatus. The initial image was evaluated for density change before and after severe storage. The image density was evaluated using a reflection densitometer 500 Series Spectrodensitometer manufactured by X-rite. The density reduction rate is a value indicating the solid image density before and after the severe condition at 100 minutes.

(Evaluation criteria)
A: The density reduction rate is less than 1%, and very excellent developability is exhibited.
B: The density reduction rate is 1% or more and less than 5%, and exhibits excellent developability.
C: The density reduction rate is 5% or more and less than 7%, and shows developability having no practical problem.
D: The density reduction rate is noticeable as 8% or more, and the developing member is fused. It is greatly inferior in developability.

<Evaluation of dot reproducibility in the second half of durability>
The dot reproducibility was evaluated by conducting an image formation test using a checker pattern of 80 μm × 50 μm shown in FIG. After outputting 5000 images in an NN environment (23.5 ° C./50%), 5000 images were output in a high temperature and high humidity environment (30 ° C./70%; HH environment). LBP-3410 was used as the image forming apparatus.

(Evaluation criteria)
A: 5 or less defects in 100 B: 6 or more and 8 or less defects in 100 C: 9 or more and 15 or less defects in 100 D: 16 or more defects in 100

  100 electrostatic latent image carrier (photoconductor), 102 toner carrier, 114 transfer member (transfer roller), 116 cleaner, 117 contact charging member (charge roller), 121 laser generator (latent image forming means, exposure device) , 123 laser, 124 register roller, 125 conveying belt, 126 fixing device, 140 developing device, 141 stirring member, 7 heating fixing device, 21 plate heater, 21a substrate, 22 thermistor, 24 heater holder, 30 fixing roller, 31 Core Bar, 32 Low Thermal Conductive Elastic Layer, 33 High Thermal Conductive Layer, 41 Core Bar, 42 Elastic Layer, 43 Release Layer, 63 Pressure Roller, Nh Heating Nip, Nt Fixing Nip, P Recording Material, T Toner

Claims (8)

A magnetic toner having at least a binder toner, a magnetic material, a magnetic toner particle having at least a release agent, and an inorganic fine powder,
The surface of the magnetic material is treated with a fatty acid or a fatty acid metal salt;
The magnetic toner particles have a methanol wettability Wa of 25 ° C. of 30% by volume or more and 50% by volume or less, a methanol wettability Wb of 50 ° C. of 55% by volume or less, and a methanol wettability Wc of 70 ° C. A magnetic toner characterized by satisfying
Wc−Wa ≧ 40 (Formula 1)   2. The magnetic toner according to claim 1, wherein the fatty acid or fatty acid metal salt containing a carbonyl carbon has a carbon number Cm of 16 or more and 22 or less.   The magnetic toner according to claim 1, wherein the release agent is an ester wax. When the carbon number of the fatty acid containing the carbonyl carbon of the fatty acid or fatty acid metal salt is Cm, the carbon number of the alcohol component of the ester wax is Cwa, and the carbon number of the acid component containing the carbonyl carbon is Cwb, Cm, Cwa and Cwb The magnetic toner according to claim 1, wherein the following formulas 2 and 3 are satisfied.
| Cm-Cwa | ≦ 6 (Formula 2)
| Cm−Cwb | ≦ 6 (Formula 3)   The processing amount of the fatty acid or fatty acid metal salt is 1.5% by mass or more and 5.0% by mass or less with respect to 100% by mass of the magnetic substance, and is processed in an aqueous phase. The magnetic toner according to any one of the above.   6. The magnetic toner according to claim 1, wherein the fatty acid portion of the fatty acid or fatty acid metal salt is stearic acid.   The ester wax is a total amount of volatile components (A) detected after the peak detection time of hydrocarbons having 16 carbon atoms when measured at a heating temperature of 200 ° C. and a heating time of 10 minutes in the heating adsorption / GC / MS analysis. The magnetic toner according to claim 1, wherein the toner is 1500 ppm or less (in terms of hexadecane).   The magnetic toner according to claim 1, wherein the magnetic toner particles are produced in an aqueous medium.

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