JPH03103865A - Bright magnetic toner - Google Patents

Abstract

PURPOSE:To obtain the bright magnetic toner suitable for coloration of the toner by applying the process for production of a pearl pigment. CONSTITUTION:A light coherent thin film consisting of a transparent metal oxide 11 having a high refractive index is formed on a planar magnetic particle 10. The color of the magnetic particle 10 is optically erased by the interference of the reflected light from the thin film surface of the metal oxide 11 and the reflected light from the boundary between the thin film of the metal oxide 11 and the magnetic particle 10, by which the magnetic particle is colored to the bright and beautiful color having brightness. Since the principle of the coloration is the interference effect of light, the coloration of many and diversified colors is enabled simply by changing the film thickness of the metal oxide 11. The bright magnetic toner suitable for the coloration is obtd. in this way.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to toners used in electrophotography, magnetic recording, etc., and is particularly applicable to monocomponent magnetic toner for electrophotography and colorization of toner for magnetic recording. The present invention relates to suitable glossy magnetic toners.

<Prior art> Conventionally, for example, in the magnetic recording method, a magnetic latent image obtained by a magnetic method on a magnetic recording medium is developed with magnetic toner, and this is transferred and fixed onto an object to be transferred, thereby creating a visible image. Forming an image is performed.

The magnetic toner used here is F. , 304 or barium-ferrite powder and resin are kneaded and pulverized.

On the other hand, pearl pigments are known as pigments that exhibit luster.
It is manufactured by suspending a transparent mica-like substrate in a dilute acidic titanium salt aqueous solution, heating this suspension, and forming a permanent titanium oxide thin film on the substrate surface by thermal hydrolysis, and sintering this.

Furthermore, according to JP-A-51-7176, an iron oxide pigment has been developed in which a thin film of titanium oxide is formed on an opaque mica-like ferric oxide surface using the above-mentioned pearl pigment production method.

<Problems to be Solved by the Invention> Since the magnetic powder in conventional magnetic toners is black or blackish-brown, when simply mixing the magnetic powder and a coloring agent or simply covering the magnetic powder with a coloring agent, it is difficult to The color of the toner became cloudy due to black or blackish brown, and a toner with a clear and bright color could not be obtained.

The present invention relates to toners for magnetic recording or semi-magnetic toners for electrophotography, and an object of the present invention is to provide a glossy magnetic toner suitable for coloring by applying a pearl pigment manufacturing method.

<Means for Solving the Problems> The present invention has been made to achieve the above-mentioned objects, and includes an optical interference thin film made of a transparent metal oxide with a high refractive index on plate-shaped magnetic particles. The object of the present invention is to provide a glossy magnetic toner having the following properties.

The plate-shaped magnetic particles may be a single magnetic particle or a mixture of several types of magnetic particles, or may be a substance having a magnetic thin film on the surface of the plate-shaped nonmagnetic particles.

<Function> The above-mentioned glossy magnetic toner has a transparent metal oxide thin film with a high refractive index on the plate-shaped magnetic particles, so that the repulsive light from the surface of the metal oxide thin film and the magnetic property of the metal oxide thin film are prevented. The color of the magnetic particles is optically erased by interference with the reflected light from the interface with the particles, and the particles are colored in an elegant color with a clear luster.

In addition, since the principle of coloring is the interference effect of light, a wide variety of colors can be produced by simply changing the thickness of the metal oxide film.

Furthermore, since it does not contain color pigments, toners of all tones have almost the same physical properties, and can be uniformly and easily dispersed and mixed.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. Figure 1 shows
FIG. 1 is a sectional view showing an embodiment of the present invention.

In the figure, as the plate-shaped magnetic particles 10, generally known magnetic substances such as nickel, barium ferrite, magnetite, etc., or alloys and compounds thereof can be used. These plate-shaped magnetic particles have an average diameter of 2 to 200 μm.
The thickness is preferably 5 to 100 μm and 0.3 to 5 μm, preferably 0.5 to 3 μm. The shape may be a disc, a hexagonal plate, a rectangular plate, a rhombus plate, or any other appropriate shape as long as it has good planarity.

As the metal oxide 11, titanium oxide exhibits a high refractive index,
It is possible to use tin oxide, zirconium oxide, etc. As a method for forming a thin film using a metal oxide, the plate-shaped magnetic particles 10 are immersed in an organometallic compound solution, pulled up and dried, and then burned to decompose the organometallic compound to form a thin film made of a metal oxide. A method of suspending plate-shaped magnetic particles in a dilute acidic solution of a metal salt, hydrolyzing the metal salt to precipitate a hydrated metal oxide on its surface, and burning the metal compound. Examples include methods of forming a thin film, but the method is not limited to these methods. Here, the most commonly used method for forming a titanium oxide thin film will be explained in more detail.

Temperature of about 50-100°C and polo. A first stream of an aqueous solution of a titanium salt of 0.001 to 5 molar containing free acid corresponding to 0.002 to 3N and at the same time an aqueous suspension of the material to be coated having a molecular weight of 5 to 5.5 This can be avoided by adding an aqueous alkali metal solution of ION or ammonium hydroxide or ammonium gas. The base charge rate is maintained just enough to neutralize the acid contained in the titanium salt solution as well as the acid produced during the reaction. The titanium salt charge rate is maintained in the range of about 0.01 to 20.times.10@-5 moles of titanium salt per square meter of surface to be coated per minute.

According to the invention, the hydrolysis is carried out in aqueous solution at 50-100°C, in particular 70-80°C. In this hydrolysis, the amount of titanium salt supplied within unit time,
Care must be taken that the amount of titanium dioxide hydrate produced therefrom is balanced with the surface to be coated, i.e. it is substantially completely absorbed by the surface and does not remain in the reaction solution in free suspension. .

Hydrolysis is suitably carried out in such a way that the article or substance to be coated is placed in water to form a suspension or, in the case of articles, suspended from above. After heating the suspension to the required temperature (approximately 50-100°C), 0.
A dilute titanium salt aqueous solution of 0.001 to 5 mol is fed under stirring, particularly below the surface of the liquid. Preferably, the concentration is in the range of 0.2 to 2 molar. Salt solution is 0.002-3N,
Especially 0.2~2. Contains the free acid corresponding to ON. At the same time, dilute aqueous base solution or ammonia gas is fed to the suspension. This base is fed to the titanium salt solution. This base is necessary to neutralize both the acid contained in the titanium salt solution and the acid produced continuously during hydrolysis.

Advantageously, both the base and the titanium salt solution are supplied by suitable metering devices. Suitable metering devices include, for example, dispensing pumps and rotameters.

Particularly useful as hydrous bases are alkali metal hydroxide solutions, the preferred being sodium or potassium hydroxide or ammonium hydroxide. 0.025~1
It is suitable to use base solutions of 0, especially 1 to 1 loN. The amount of diluted salt fed per unit time can be varied within narrow limits without producing undesirable by-products. It has been found that pH values in the range from 0.5 to 5.0, in particular from 1.5 to 2.5, are particularly suitable for producing good coatings. Buffers can also be added to maintain this pH value if necessary. All buffer systems customary for this pH range can be used, such as phosphate, acetate, citrate or glycol buffers.

According to the invention, only sufficient titanium salt is supplied per unit time to the surface to be coated, so that all the titanium hydroxide or titanium dioxide hydrate can be applied to the surface without forming mobile by-products in suspension. It can be made so that it can be deposited.

By varying the concentration or feed rate of the titanium salt solution used, both variables may be influenced by the proportion of titanium dioxide or hydrous titanium dioxide required to saturate the surface of the substrate material. It is clear that this will have a significant impact.

The amount of titanium salt used per minute is of the order of 0.01 to 20.times.IO-' mol of titanium salt per square meter of surface to be coated.

The reaction can vary widely with respect to time, depending on the titanium salt solution used and the material to be coated. Of course, usage also plays an important role. For example, coatings can be obtained on certain supports after 1 to 4 hours (e.g. in the case of barium sulfate), whereas in the case of other supports considerably longer times, up to several days, are required.

According to the present invention, a hydrous titanium dioxide coating is produced.

These coatings become thin films of titanium dioxide that are completely or partially dehydrated by simply being left in the air or by forced drying.

Furthermore, as the plate-shaped magnetic particles 10, plate-shaped non-magnetic particles 2
A magnetic thin film 21 may be formed on the zero surface. Natural mica and composite mica are used as the plate-like nonmagnetic particles.

As the magnetic thin film, nickel, barium-ferrite,
Generally known magnetic materials such as magnetite, alloys and compounds thereof, etc. can be used. Examples of the thin film method include plating, vapor deposition, and sputtering, but the method is not limited to these methods.

<Example> The present invention will be specifically explained below using examples.

Example-1 1000 ml of sulfuric acid acidic solution of titanium sulfate (TiO,
25 plate-shaped nickel particles with an average diameter of 10 μm (converted to 25 g)
Add 0 g and stir at a rotation speed of 500 rpm.
Heat at 5-100°C for 1 hour.

After cooling, neutralize with sodium hydroxide and wash with water until sulfate ions are no longer detected. This was filtered and dried to obtain a glossy blue magnetic toner.

Example 2 40 g of titanium tetrachloride was dissolved in 100 ml of water, 250 g of plate-shaped nickel particles were added, and the same operation as in Example 1 was performed to obtain a glossy dark green magnetic toner.

Example-3 White mica with a 1 μm nickel film formed by plating (
(average diameter 10 μm) 50g was added to a sulfuric acid acidic solution of titanium sulfate 1
0 0 0 ml (20g TiOz equivalent)
), and the same operations as in Example 1 were carried out to obtain a glossy purple magnetic toner.

Effects of the Invention> The present invention is as described above, and since a high refractive index and transparent metal oxide thin film is provided on the plate-shaped magnetic particles, the color of the magnetic particles is erased by an optical effect, making it clear. It is possible to obtain a toner having a glossy and elegant color.

Furthermore, since the principle of coloring is light interference, toners colored in a wide variety of colors can be obtained by simply changing the thickness of the metal oxide film.

Furthermore, since it does not contain coloring pigments, toners of all tones exhibit almost the same physical properties, ensuring uniform dispersion and mixing.
It is a 1-ner that can be easily performed and can be widely applied to magnetic image forming techniques such as electrophotography, magnetic recording, and magnetography.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of the glossy magnetic toner of the present invention, and FIG. 2 is a cross-sectional view of an example of plate-shaped magnetic particles used in the present invention. l1 0...Plate-shaped magnetic particles 1...Metal oxide 0...Plat-shaped non-magnetic particles 1...Magnetic particle patent Convex printing table 1 2

Claims (3)

[Claims] (1) A glossy magnetic toner characterized in that a light interference thin film made of a transparent metal oxide with a high refractive index is formed on plate-shaped magnetic particles. (2) The glossy magnetic toner according to claim 1, wherein the plate-shaped magnetic particles are a single magnetic particle or a mixture of several types of magnetic particles. (3) The glossy magnetic toner according to claim 1, wherein the plate-shaped magnetic particles have a magnetic thin film on the surface of the plate-shaped non-magnetic particles.