Toner for electrostatic image development

Abstract

Disclosed is a toner for electrostatic image development that satisfies both low-temperature fixing ability and excellent high-temperature storage stability, achieves excellent charge property and shatter resistance, and consequently can form a high-quality image even by a high-performance machine such as a high-speed machine. The toner is composed of toner particles obtained by forming a shell layer containing a styrene-acryl-modified polyester resin on the surface of each of core particles comprising a binder resin containing at least a styrene-acrylic resin. The styrene-acryl-modified polyester resin is obtained by bonding a styrene-acrylic polymer segment to a terminal of a polyester segment, and the content of the styrene-acrylic polymer segment in the styrene-acryl-modified polyester resin is 5% by mass or more and 30% by mass or less.

Description

technical field [0001] The present invention relates to a toner for developing an electrostatic charge image used for image formation in an electrophotographic system. Background technique [0002] In recent years, in the field of toners for electrostatic image development (hereinafter simply referred to as "toners"), in response to market demands, the electrophotographic devices applicable to them and the toners that can be used therein Development moves fast. [0003] For example, as a toner corresponding to high image quality, each toner particle has uniform development behavior, thereby remarkably improving the reproducibility of minute dots, and therefore, a toner with a narrow particle size distribution is required. . However, it is not easy to obtain a toner with a narrow particle size distribution by the conventional pulverization method. On the other hand, an emulsion polymerization coagulation method has been proposed as a production method capable of arbitraril...

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Problems solved by technology

[0008] However, styrene-acrylic resins and polyester resins lack affinity. When styrene-acrylic resins are used as the binding resin constituting the core particles and polyester resins are used as the shell resin constituting the shell layer, there are difficulties in forming Thin and uniform shell layer cannot obtain sufficient heat-resistant preservation

Moreover, there is also a problem in that it is difficult to control the shape of the toner particles because the fusion of the core particles and the fine particles that should form the shell layer is difficult to occur, so that it is difficult to produce toner particles with smooth surfaces. As a result, High chargeability cannot be obtained, and peeling of the shell layer occurs due to agitation of the toner in the developer during continuous printing. As a result, image noise occurs in the obtained image during image formation, and good image quality cannot be ensured.

[0013] However, in the toner disclosed in Patent Document 4, there are problems in that a uniform shell layer cannot be formed due to excessive affinity with styrene-acrylic resin due to the small content of the polyester segment, and, It is difficult to design a toner with a low softening point while maintaining a high glass transition temperature, so that both low-temperature fixability and heat-resistant storage properties cannot be satisfied

[0014] In addition, since the toner resin disclosed in Patent Document 5 has a structure in which a styrene-acrylic polymer is graft-polymerized on a main chain formed of polyester, molecular crosslinking occurs during the synthesis of the resin. However, it is difficult to control the molecular weight of the styrene-acrylic polymer segment. Therefore, the toner that forms the shell layer by such a resin still cannot satisfy both the low-temperature fixability and the heat-resistant storage property.

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