JPS5898740A - Red magnetic toner - Google Patents

Abstract

PURPOSE:To obtain a fresh red colored magnetic toner and to obtain copied images having excellent contrast and halftones by sticking red tar dyes on the surface of gamma-Fe2O3 magnetic power having coercive force in a specific value range. CONSTITUTION:Red colored magnetic powder is obtained by such a method of subjecting gamma-Fe2O3 magnetic powder having 50-200 oersted coercive force and about 2-50m<2>/g specific surface area and tar type red dyes such as ''Rhodamine B '', ''Lake Red C '' or the like to a ball mill treatment for 5hr in water then drying the same. Such powder is kneaded together with a binder such as polystyrene resin and the mixture is ground, whereby a red granular magnetic toner of about 10-20mu particle size is obtained. By the use of such toner, fresh red colored pictures having excellent contrast and halftones are obtained with good resolution and reproducibility of fine images.

Description

[Detailed description of the invention] The present invention relates to a red magnetic toner for electrophotography.

Currently, electrophotographic technology is mainly used for copying machines, but depending on developments, it may be applied to photography in a broader sense. Therefore, the use of the red magnetic toner of the present invention is not limited only to copying machines.

The basic principle of electrophotography is to create a visible image by forming a static latent layer on an image forming medium that utilizes photoconductive phenomena, and attaching colored charged fine particles (toner) to this layer using electrostatic attraction. ,
A copying machine transfers and fixes a visible image onto a suitable recording medium such as paper.

Until today, monochrome (black) copies have been the main type of copying.

The toner used is simply black.

There are two types of toner: two-component toners consisting of a colored substance and a magnetic carrier, and one-component toners in which the colored substance itself also serves as a carrier. Two-component toners typically consist of carbon black and iron powder, and a typical one-component toner is magnetite (iron black).

In recent years, there has been a trend toward practical application of color copying technology, and the development of toners corresponding to this technology has progressed.The coloring components of two-component toners include white or light-colored oxides dyed with organic dyes. A method has been proposed (Patent No. 1035709).

However, r -FezO@ (magnetite) is a promising material for non-black one-component toner.

It is said that the color changes depending on the manufacturing method, such as yellowish red, red fuku, or purple, but it is usually brown in color. The inventors of the present application are
We attempted to dye 20 g with a red organic dye and found that a tar-based dye was most suitable.

That is, according to the present invention, there is provided a red magnetic toner characterized in that a red tar-based dye is adhered on the surface of 20g γ-Fe magnetic powder having a coercive force of 50-200 Oersteds.

The γ-F e2 (%) of the red magnetic toner of the present invention is defined as: When the coercive force exceeds 200 oersteds, it becomes difficult for the toner to separate from the magnetic plasticine or magnetic roller. When transferring to a transparent medium (such as paper), the contrast deteriorates, making precise transfer difficult.

Although the particle size of r-Fe10B is not an essential requirement like coercive force, fine color tone and fine reproduction can be obtained, but the amount of binder required is large. Is the preferred particle size measured by specific surface area? -5Od/1/.

Lake red, litol, and rhodamine are tar pigments suitable for producing the red magnetic toner of the present invention.

Al with Tipu Maroon, Erythrosine, etc. Moreover, these products have been confirmed to be safe.

In order to produce the red magnetic toner of the present invention, it is sufficient to prepare the 1-Fe1OB powder as described above, mix and stir it with an aqueous solution of the dye in an organic solvent, separate the solution, and then dry it.

A clear red color can be obtained if the amount of the dye attached is 5 weight or more based on γ-Fe*Om.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Example-1 Cubic γ-Fez (%
Powder 45.9 and Rhodamine B51 were added to just under 200 g of water, and the mixture was ball milled for 5 hours. After treatment, the granules are separated from the balls and dried into mud. The adhesion amount of Rhodamine B was about 9%.

This colored γ~Fed Oz powder was thoroughly kneaded with 50% by weight of polystyrene resin (Picolastic, manufactured by Esso) using two rolls at a temperature of 170°C.

It was cooled to form a granular toner with a particle size of 10 to 20 μm. Using the red magnetic toner with an ordinary electronic copying machine.

When I made a red monochrome copy, it turned out to be a clear red.

A reproduced image with excellent contrast and halftone was obtained.

・Example-2 Spindle-shaped r − having a specific surface area of 40w1/i
It was treated in the same manner as in Example 1 using 45 g of Fed (% powder) and 5 g of Lake Red C. The amount of pigment attached was about 9.5-
in,! The color tone of the produced toner was clearer than that of Example 1. When used as a toner in the same manner as in Example 1, even clearer and more precise copied images were obtained.

The one-component red magnetic toner of the present invention has industrial applicability as a red toner for color electrophotography, which is being put into practical use.

Patent applicant: Mitsubishi Metals Corporation Representative Patent Attorney Masahiro Matsui

Claims (1)

[Claims] r- with a coercive force of t 50-200 oersted
A red magnetic toner characterized by having a red tar-based pigment adhered to the surface of Fe10B magnetic powder.