JPH04268570A - Color magnetic toner - Google Patents

Abstract

PURPOSE:To obtain images of bright colors with good fixability by treating magnetic powder in such a manner that its dark brown color turns into gray, thereby preventing the colors of the coloring agents to be incorporated into the toner from having a dark brown color. CONSTITUTION:This toner contains the magnetic powder which is treated rich in Fe<2+> by reduction of the surface of Fe3O4, a binder resin and the coloring agents. Such compsn. as to make the toner rich in Fe<2+> is selected and an aq. ferrous sulfate or ferrous chloride soln. is neutralized by an alkali and is heated in gaseous H2 atmosphere or the powder is codeposited with the alkali from a soln. mixture composed of a ferrous salt and a ferric salt. The resulted Fe3O4 magnetic powder rich in Fe<2+> is dispersed into an aq. soln. and a coupling agent and the coloring agents are added thereto to hydrolyze the magnetic powder and to simultaneously bond the coloring agents to the magnetic powder in the case of attaching the coloring agents to the magnetic powder.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color magnetic toner used for developing electrostatic latent images in electrophotography, electrostatic printing, and the like.

0002

[Prior Art] In image forming methods such as electrophotography, an electrostatic charge image is generally developed on the surface of a photoreceptor drum using a photoconductive substance by various methods, and toner is guided to the electrostatic charge image for development. do. Then, the toner image is transferred to a transfer material such as paper, and the toner is further fixed by heating, pressure, etc. to obtain a copy. When developing an electrostatic charge image,
The charged toner particles are attached to the photosensitive drum side by electrostatic attraction. There are two types of developing methods using toner particles: one uses a two-component developer containing a mixture of toner and a carrier, and the other uses a one-component developer consisting only of toner.

The magnetic toner used in these developers has conventionally used magnetite, ferrite, etc. as the magnetic material, and since these magnetic materials have a black or dark brown color, they cannot produce clear color images. This is a major obstacle to achieving this. Magnetic toner suitable for color copying includes
In order to obtain a vivid red or sepia colored magnetic toner, it is known to use γ-iron oxide particles as a magnetic substance in the toner. There are various ways to obtain γ-iron oxide, but if the magnetic material is used, the color tone will be poor if the particles are large, so the particles are made small, but if this is done, the copied image will be yellowish and the toner's fixability will be affected. There is a problem that the amount decreases. Furthermore, the dispersibility of the γ-iron oxide particles in the binder resin is poor, resulting in poor toner durability and sometimes resulting in poor transfer.

[0004] For this reason, after treating α-iron oxide particles with an aluminum compound as magnetic powder, reduction and
A color magnetic toner using alumina-treated γ-iron oxide particles obtained by heat treatment for oxidation has been proposed (Japanese Patent Application Laid-open No. 213860/1983). In other words, if large magnetic particles are included, only a small amount of colorant or binder resin will bind to them, making it impossible to obtain a clear color image. Therefore, it is necessary to treat α-iron oxide particles with an aluminum compound. By doing so, the cohesive force of the aggregates generated by the heat treatment is reduced, and the magnetic particles are made into fine particles. In addition, there are various proposals for magnetic color toners, but in order to have good fixing properties and obtain clear and good red images, the average particle size is 1.0 to 6.0μ and the surface is There is a magnetic color toner prepared from a mixture of γ-Fe2 O3-treated Fe3 O4 and γ-Fe2 O3 with an average particle size of 0.01 to 0.6 μm (Japanese Unexamined Patent Publication No. 58-215661). . Furthermore, in order to hide the color tone of the magnetic material and obtain a richly colored magnetic color toner, the surface of the magnetic powder is subjected to hydrolysis treatment of a titanium ester compound, and then the color magnetic powder is coated with titanium oxide. Toner is also known (Japanese Patent Application Laid-open No. 1983-
87558).

[0005]

[Problems to be Solved by the Invention] In order to obtain clear and good color images, conventional color magnetic toners
Treatment to reduce the cohesive force of iron oxide magnetic powder,
Although γ-Fe2 O3 and Fe3O4 are used as magnetic powders, since the magnetic powder itself has a blackish brown color, the blackish brown color is mixed with the color of the coloring agent, making it difficult to obtain images with sufficiently clear colors. Furthermore, when using conventional magnetic powder whose surface is coated with titanium oxide, there is a problem in that the magnetic powder particles become large and the fixing performance is reduced. Therefore, the present invention aims to treat the blackish-brown color of the magnetic powder to gray so that the color of the colorant contained in the toner does not become blackish-brown, thereby making it possible to obtain clear color images with good fixing properties. With the goal.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a color magnetic toner containing a magnetic powder whose surface is reduced to make it rich in Fe2+ by reducing the surface of Fe3O4, a binder resin, and a colorant. did. In order to obtain the Fe2+-rich magnetic powder described above, select a composition that is Fe2+-rich, neutralize the ferrous sulfate or ferrous chloride aqueous solution with an alkali, and heat it in an H2 stream, or 1
A mixed solution of iron salt and ferric salt is co-precipitated with alkali. When adding a coloring agent to the obtained Fe2+-rich Fe3O4 magnetic powder, the magnetic powder is dispersed in an aqueous solution,
A coupling agent and a coloring agent are added and hydrolyzed, and at the same time, the coloring agent is chemically bonded to the magnetic powder. F in this case
The proportions of e3 O4 and coupling agent added were 100 parts by weight and 1 to 5 parts by weight, respectively.

As the coupling agent, silane-based, titanium-based, zirco-aluminum-based, silicon-based, and alumina-based organic compounds can be used. As a silane-based organic compound, γ
-Chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyl tris(β-methoxyethoxy)
Silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane , N-β-(
aminoethyl)-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-β
Commercially available products such as (aminoethyl)γ-aminopropylmethyldimethoxysilane can be used.

Examples of titanate-based organometallic compounds include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzene sulfonyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, and tetraisopropyl bis(dioctyl phosphite). titanate, tetraoctyl
Bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis(ditridecyl) phosphite titanate, bis(dioctylpyrophosphate) oxyacetate titanate, bis(dioctylpyrophosphate) phosphate)
Commercially available products such as ethylene titanate can be used.

Pigments or dyes can be used as the coloring agent, and pigments include cadmium yellow, Hansa yellow G, C.I. I.
Pigment Yellow 17, Varifast Yellow 31
20. Permanent yellow NCG, pyrazolone orange G, benzine orange G, cadmium red, brilliant carmine 3B, brilliant carmine 6B, fast violet B, quinacridone, magenta, rhodacine 6G lake, phthalocyanine blue, fast sky blue, malachite green lake can be applied. . Further, as the dye, for example, monoazo dye and anthraquinone dye can be used.

As the binder resin, when applied to a heat fixing method, styrenes, vinyl esters, α-methylene aliphatic monocarboxylic acid esters, acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers, vinyl lactones are used. , homopolymers made by polymerizing monomers such as N-vinyl compounds, copolymers made by copolymerizing two or more of these monomers, or mixtures thereof, bisphenol-type epoxy resins, oil-modified epoxy resins, polyurethanes Non-vinyl plastic resins such as resins, cellulose resins, and polyester resins can be used. In addition, when applying to the pressure fixing method, waxes, rosin derivatives, alkyd resins, silicone resins, polyolefins,
Ethylene copolymers, rubbers, etc. can be applied. Furthermore, the color magnetic toner of the present invention includes nigromine dyes and metal alloy (Cr) azo dyes as charge control agents, polyolefins, higher fatty acids and fatty acid metal salts as release agents, and silica as a fluidity modifier. Alumina, titanium oxide, etc. may be mixed as necessary. When producing the color magnetic toner of the present invention, it is produced by a known pulverization method, spray drying method, or suspension polymerization method using the above-mentioned magnetic powder, colorant, binder resin, and charge control agent. .

[0011]

[Example] The color magnetic toner of the present invention contains at least a magnetic powder, a binder resin, and a colorant, and the magnetic powder used was one in which the surface of Fe3O4 was reduced to make it Fe2+ rich. It is characterized by Next, an example of producing the color magnetic toner of the present invention will be described.

(Preparation Example 1) Ferrous sulfate heptahydrate was dissolved in distilled water, heated to 60° C., and a 6N aqueous sodium hydroxide solution was added to cause a neutralization reaction. Furthermore, H2 gas is blown into the suspension system containing the reacted iron hydroxide, heated to 400°C, the precipitate is filtered and dried, and the surface is Fe2+ rich Fe3.
Obtained O4. Next, 100 parts by weight of the obtained Fe3 O4 was dispersed in an aqueous solution, and N-β (amino-ethyl) α (amino-propyl) methyl methoxy silane 2
Part by weight of a 10% ethanol solution was added for hydrolysis. During this hydrolysis, red dye (Orient Chemical)
RED-RR) was added thereto and stirred. 100 parts by weight of the magnetite obtained above, 80 parts by weight of styrene-n-butylene methacrylate copolymer (weight average molecular weight 240,000, number average molecular weight 54), 6 parts by weight of polypropylene (Viscol 550P manufactured by Sanyo Chemical Co., Ltd.) and the above-mentioned. and 10 parts by weight of the same red dye. This mixture was kneaded with a kneader, cooled and solidified, and then pulverized with a jet mill and classified to obtain a red magnetic toner having an average particle size of 10 μm. Using the obtained red magnetic toner, a copying test was conducted using a commercially available copying machine (Casio LCS124 modified machine), and a clear red image was obtained, with good fixing properties.

(Preparation Example 2) 100 parts by weight of the Fe2+-rich Fe3O4 obtained in Preparation Example 1, 10 parts by weight of a 10% ethanol solution of isopropyl triisostearoyl titanol, and an organic pigment (C.I Pigment Yellow 1)
2) 5 parts by weight were mixed and hydrolyzed, at the same time the pigments were chemically bonded, and further treated with a spray dryer. Next, 40 parts by weight of the magnetite obtained above, 51 parts by weight of styrene-n-butyl copolymer (same molecular weight as above), 3 parts by weight of polypropylene, and a charge control agent (Orient Chemical Co., Ltd. Drifst Yellow) 1 part by weight and 5 parts by weight of the same organic pigment were mixed. This mixture was kneaded with a kneader, cooled and solidified, and then pulverized with a jet mill and classified to obtain a yellow magnetic toner having an average particle size of 10 μm. A copying test was conducted using the obtained yellow magnetic toner using the same copying machine as in Preparation Example 1, and a clear yellow image was obtained with good fixing properties.

[0014]

Effects of the Invention The color magnetic toner of the present invention has a surface of Fe3O4 as magnetic powder that is reduced and treated to be rich in Fe2+, resulting in a color close to gray, which is different from the conventional magnetic toner using dark brown magnetic powder. The color does not appear blackish as in the case of . Furthermore, unlike the case where the outer periphery of magnetic powder is coated, the color of the magnetic powder itself is made gray, and there is no reduction in fixing properties or impairing developability.

Claims (1)

[Claims] [Claim 1] The surface of Fe3O4 is reduced to F
A color magnetic toner for developing electrostatic images, characterized by containing e2+-rich magnetic powder, a binder resin, and a colorant.