Magnetic toner

Abstract

A magnetic toner contains magnetic toner particles containing a binder resin, a release agent, and a magnetic body and inorganic fine particles present on the surface of the magnetic toner particles, wherein the inorganic fine particles present on the surface of the magnetic toner particles contain metal oxide fine particles, the metal oxide fine particles containing silica fine particles, and optionally containing titania fine particles and alumina fine particles, and a content of the silica fine particles being at least 85 mass% with respect to a total mass of the silica fine particles, the titania fine particles and the alumina fine particles, the coverage ratio of the magnetic toner particles' surface by the inorganic fine particles and the coverage ratio by the inorganic fine particles fixed to the magnetic toner particles' surface reside in a prescribed relationship, the binder resin contains a polyester resin, the release agent contains an ester compound, and an endothermic peak for the magnetic toner has a prescribed value.

Description

technical field

[0001] The present invention relates to a magnetic toner used in, for example, electrophotography, electrostatic recording and magnetic recording. Background technique

[0002] Copiers and printers are undergoing device miniaturization and energy efficiency improvement, and against this background, it is preferable to use a magnetic one-component developing system using an advantageous magnetic toner.

[0003] In the magnetic one-component developing system, development is performed by conveying magnetic toner into a developing area using a toner carrying member (hereinafter referred to as a developing sleeve) into which a device generating a magnetic field such as a magnetic roller is introduced. . In addition, mainly in the region where the magnetic toner is controlled by a toner control member (hereinafter, also referred to as a developing blade), by friction between the magnetic toner and a triboelectric charge imparting member such as a developing sleev...

Examples

Embodiment 1

[0402] (image forming equipment)

[0403] The image forming apparatus was LBP-3100 (Canon, Inc.) equipped with a small-diameter developing sleeve having a diameter of 10 mm; the printing speed thereof was changed from 16 sheets / minute to 20 sheets / minute. The equipment was also modified so that the fixing temperature of the fixing unit was lowered by 35°C. FOX RIVER BOND paper (105g / m 2 ) is used as a recording medium. In an image forming apparatus equipped with a small-diameter developing sleeve, durability can be strictly evaluated by changing the printing speed to 20 sheets / minute. In addition, by using the above-mentioned recording medium that exhibits a large amount of water absorption and provides poor transfer of the magnetic toner at the fixing temperature, and by changing the developing sleeve to a small-diameter developing sleeve, lowering the fixing temperature, and under a high-temperature, high-humidity environment Continuous paper feeding evaluation is perform...

Embodiment 2-33 and comparative example 1-29

[0438] Toner evaluation was performed under the same conditions as in Example 1, using Magnetic Toner 2-33 and Comparative Magnetic Toner 1-29 as the magnetic toner. The results of the evaluation are shown in Table 7. In Comparative Examples 7 and 9, there were very many free silica fine particles on the developing sleeve and image defects were generated in the form of vertical stripes. When the magnetic toner particles 20 used in Comparative Example 12 were left overnight in a high-temperature, high-humidity environment, a large number of aggregates were generated by the magnetic toner and image defects were generated in the form of vertical stripes.

[0439] [Table 7-1]

[0440]

[0441] [Table 7-2]

[0442]

technical field

[0001] The present invention relates to a magnetic toner used in, for example, electrophotography, electrostatic recording and magnetic recording. Background technique

[0002] Copiers and printers are undergoing device miniaturization and energy efficiency improvement, and against this background, it is preferable to use a magnetic one-component developing system using an advantageous magnetic toner.

[0003] In the magnetic one-component developing system, development is performed by conveying magnetic toner into a developing area using a toner carrying member (hereinafter referred to as a developing sleeve) into which a device generating a magnetic field such as a magnetic roller is introduced. . In addition, mainly in the region where the magnetic toner is controlled by a toner control member (hereinafter, also referred to as a developing blade), by friction between the magnetic toner and a triboelectric charge imparting member such as a developing sleev...

Examples

Embodiment 1

[0402] (image forming equipment)

[0403] The image forming apparatus was LBP-3100 (Canon, Inc.) equipped with a small-diameter developing sleeve having a diameter of 10 mm; the printing speed thereof was changed from 16 sheets / minute to 20 sheets / minute. The equipment was also modified so that the fixing temperature of the fixing unit was lowered by 35°C. FOX RIVER BOND paper (105g / m 2 ) is used as a recording medium. In an image forming apparatus equipped with a small-diameter developing sleeve, durability can be strictly evaluated by changing the printing speed to 20 sheets / minute. In addition, by using the above-mentioned recording medium that exhibits a large amount of water absorption and provides poor transfer of the magnetic toner at the fixing temperature, and by changing the developing sleeve to a small-diameter developing sleeve, lowering the fixing temperature, and under a high-temperature, high-humidity environment Continuous paper feeding evaluation is perform...

Embodiment 2-33 and comparative example 1-29

[0438] Toner evaluation was performed under the same conditions as in Example 1, using Magnetic Toner 2-33 and Comparative Magnetic Toner 1-29 as the magnetic toner. The results of the evaluation are shown in Table 7. In Comparative Examples 7 and 9, there were very many free silica fine particles on the developing sleeve and image defects were generated in the form of vertical stripes. When the magnetic toner particles 20 used in Comparative Example 12 were left overnight in a high-temperature, high-humidity environment, a large number of aggregates were generated by the magnetic toner and image defects were generated in the form of vertical stripes.

[0439] [Table 7-1]

[0440]

[0441] [Table 7-2]

[0442]

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