JPH06102696A - Encapsulated magnetic toner and its production - Google Patents

Abstract

PURPOSE:To obtain a encapsulated magnetic toner hiding the color of the core material and having clear coloring property by forming a core material based on magnetic particles and a layer of an inorg. metallic compd. having a high refractive index. CONSTITUTION:A shell material covering a core material 11 based on magnetic particles is formed as a layer 12 of an inorg. metallic compd. having a high refractive index. One kind of magnetic powder, a mixture of several kinds of magnetic powders or powder consisting of magnetic powder, iron such as ferrite or magnetite, cobalt, nickel and a polymer is used as the core material 11. The pref. refractive index of the inorg. metallic compd. is >=1.9. The core material is dispersed in a dil. soln. of a metallic salt and the inorg. metallic compd. is deposited on the surface of the core material by a precipitation reaction to produce the shell material. The resulting capsulated magnetic toner can be used as an electrophotographic toner, a magneto-graphic toner or magnetic ink for magnetic printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner used as a toner for electrophotography, a toner for magnetography, an ink for magnetic printing, and the like. The present invention relates to a toner and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, magnetic toners have been used as electrophotographic toners, magnetography toners, or magnetic toners for magnetic printing. Color magnetic toners used for electrophotographic toners and magnetography toners are generally known by kneading and pulverizing magnetic particles such as Fe ₃ O ₄ , γ-Fe ₂ O ₃ or barium ferrite, and a polymer and a colorant. Has been. (For example, Koichi Nakamura, "Development and Practical Use of Toner Materials", Japan Science Information Publishing Co., 1985)

However, since the conventional toner simply mixes black or black-brown magnetic particles and a coloring agent, turbidity occurs in the color of the toner, and a toner having a clear color cannot be obtained. Therefore, a color image formed by using the conventional toner can obtain only a dull image.

In electrophotography, it has been proposed to remove magnetic particles after heat fixing a magnetic toner having a porous wall containing magnetic particles on the outside of a heat sublimable dye. However, only heat sublimable dyes can be used. Further, when the magnetic particles are removed with a cleaning brush after fixing, there are problems that the image is damaged or cannot be completely removed, and a clear image cannot be obtained.

Further, various magnetic recording toners, for example, magnetic toners used for cards, tickets, commuter passes, or securities, are manufactured by kneading magnetic particles and a binder. In the magnetic recording layer using the above-mentioned magnetic toner, the magnetic particles are black or black brown, so that the magnetic recording layer is also black or black brown. It has been proposed that a cover layer be laminated on the magnetic recording layer in order to conceal the color of the magnetic recording layer and to color the magnetic recording layer to make it indistinguishable from other printing patterns and ink layers. The thicker the coating layer is, the more concealing the color of the magnetic recording layer, but the thicker the coating layer is, the spacing loss occurs between the magnetic recording layer and the magnetic head during use, and the read performance is deteriorated. Was.

Therefore, a method of making the coating layer as thin as possible has been proposed. For example, one provided with a coating layer using an ink containing an inorganic powder having a high hiding power such as TiO ₂ , or a coating layer formed of a metal vapor deposition film as shown in JP-A-56-114128. Something has been proposed.

However, when the conventional magnetic recording layer is used,
The coating layer containing an inorganic powder such as TiO ₂ cannot completely hide the background color of the magnetic recording layer. In addition, the coating layer formed of a metal vapor deposition film has a metallic luster, or has poor adhesion to the printing layer formed by the normal ink provided on the coating layer, and the printing layer is likely to be lost during repeated use due to repeated use of the magnetic head. There was a problem.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to a conventionally known magnetic toner, and provides an encapsulated magnetic toner which hides the color of magnetic particles and has a sharp coloring property, and a method for producing the same. To aim.

[0009]

The present invention has been made to achieve the above object, and has at least a core material containing magnetic particles as a main component and a layer composed of an inorganic metal compound having a high refractive index. It is an encapsulated magnetic toner made of a shell material. As a preferred embodiment of the present invention, the refractive index of the inorganic metal compound of the present invention is preferably 1.9 or more. Further, the present invention is a method for producing an encapsulated magnetic toner, which comprises producing a shell substance by dispersing a core substance in a dilute solution of a metal salt and precipitating an inorganic metal compound on the surface thereof by a precipitation reaction. Is.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. The present invention, around the core substance 11 mainly composed of magnetic particles,
This is a configuration in which a layer 12 made of an inorganic metal compound is provided.

As the core substance 11 of the present invention, it is possible to use a magnetic powder alone, a mixture of several kinds of magnetic powder, or a powder composed of a magnetic powder and a polymer. Here, examples of the magnetic powder include ferrite, magnetite, and other ferrous metals such as iron, cobalt, and nickel, alloys containing these elements, or compounds. When a powder composed of a magnetic powder and a polymer is used as the core substance 11, the magnetic powder and the polymer are kneaded and then pulverized, or the magnetic powder is uniformly dispersed in a polymerizable monomer, and then emulsion polymerization and suspension are performed. It may be polymerized by a method such as suspension polymerization or dispersion polymerization.

By covering the core material 11 with a layer 12 made of an inorganic metal compound, the color hiding property of the core material 11 can be improved and a clear color magnetic toner can be obtained.

Here, as the inorganic metal compound 12, titanium dioxide, zinc sulfide, lead titanate, zirconium oxide,
Cadmium sulfide, hematite, copper oxide, cobalt oxide and the like are used, but not limited thereto. As a method for producing a layer using the above-mentioned inorganic metal compound, the core substance is dipped in an organic metal compound solution, pulled up and dried, and then the organic metal compound is decomposed by firing to give an inorganic metal compound (in this case, specifically, Is a method of forming a layer composed of fine particles of a metal oxide), a method of utilizing hydrolysis of a metal salt solution, a method of utilizing hydrolysis of a metal alkoxide, and a method of decomposing a metal chelate compound. It is produced by a precipitation reaction such as a method. Here, the most general method for producing a layer of titanium dioxide will be described.

Specifically, a dilute strong acidic solution of titanium sulphate is dropped into an aqueous suspension of the core substance at 85 ° C to 100 ° C at an appropriate rate to cause hydrolysis to oxidize the surface of the core substance. This is a method of depositing and precipitating titanium. Here, the dropping rate of the dilute strong acid solution of titanium sulphate needs to be appropriately determined according to the particle size, amount, etc. of the core substance, but the hydrolyzed titanium oxide should be deposited only on the surface of the core substance. That is, it is necessary to control so as not to remain in the free aqueous solution. Furthermore, in place of the above method, an appropriate amount of urea was added to an aqueous suspension of the core substance at 50 ° C to 90 ° C, and a dilute titanium acid sulfate dilute strong acidic solution was added dropwise at an appropriate rate. A method of causing hydrolysis to deposit titanium oxide on the surface of the core substance may be used.
In this case, compared to the former method, the hydrolysis rate can be kept constant, and a more uniform layer can be formed.

Further, by coating the surface of the layer 12 made of the inorganic metal compound formed as described above with various polymer layers and colored layers in which various dyes and pigments are dispersed in the polymer, offset resistance, A highly functional encapsulated magnetic toner having adhesiveness, colorability, dispersion stability and the like can be obtained.

[0016]

In the encapsulated magnetic toner of the present invention, the core material mainly composed of magnetic particles is coated with an inorganic metal compound having a high refractive index, so that the color of the core material can be concealed and clear. Encapsulated magnetic toner having various colors can be obtained. Furthermore, the layer of the inorganic metal compound formed by the method of the present invention has good uniformity, the layer thickness can be easily controlled, and the coloring property can be controlled.

[0017]

EXAMPLES The present invention will be specifically described below with reference to examples. <Example 1> 50 parts by weight of magnetic particles having an average particle size of 0.25 μm (MAT305: trade name of Toda Kogyo Co., Ltd.) and maleic acid-modified polypropylene were heated and mixed, and then pulverized and granulated to obtain an average particle size of 1.0 μm. To obtain a core substance (A).

100 parts by weight of the substance (A) was added to 1000 parts by weight of a sulfuric acid acid solution of titanium (II) sulfate (0.8 N sulfuric acid, 10 parts by weight in terms of TiO ₂ ) and stirred at a rotation speed of 500 rpm and then at 100 ° C. for 2 hours.
Heated and boiled for hours. After cooling, neutralize with sodium hydroxide, wash with water until sulfate ions are no longer detected,
This was separated by filtration and dried to obtain a substance (B).

50 parts by weight of substance (B), polyurethane resin (Nipporan 4301: trade name of Nippon Polyurethane Co., Ltd.)
200 parts by weight and 50 parts by weight of 2,4-toluidine isocyanate were dispersed in 2000 parts by weight of methyl ethyl ketone in a solution using an ultra-high speed homogenizer (Polytron: trade name manufactured by Kinematica) at a rotation speed of 5000 rpm. To the above solution, 500 parts by weight of n-hexane was dropped, and a polyurethane resin was phase-separated around the substance (B) to form a polymer layer, and a white magnetic toner was obtained.

<Example 2> 50 parts by weight of the substance (A) of Example 1 was added to 1000 parts by weight of a sulfuric acid acid solution of titanium (II) sulfate (0.8 N sulfuric acid, 10 parts by weight in terms of TiO ₂ ) at a rotation speed of 300 rpm. After stirring, add 25 parts by weight of urea (1.5 equivalents of titanium salt),
Stir for another hour. Then, it heated at 85 degreeC and performed reaction for 3 hours. After cooling, the product was washed with water until no sulfate ion was detected, filtered and dried to obtain substance (C).

100 parts by weight of the substance (C), 20 parts by weight of styrene, 40 parts by weight of ethylene glycol dimethacrylate, 3 parts by weight of lauroyl peroxide, 50 parts by weight of soybean oil, and 20 parts by weight of phthalocyanine blue were sufficiently stirred and mixed. Using a homogenizer, rotate the above mixture in 1000 parts by weight of water in which 5 parts by weight of colloidal calcium phosphate and 0.1 part by weight of sodium dodecylbenzenesulfonate are dispersed.
While stirring at 10000 rpm, heat the temperature of the solution to 70 ℃,
The polymerization reaction was carried out for 10 hours to form a colored layer.

Thereafter, hydrochloric acid was added to decompose and remove the colloidal calcium phosphate and sodium dodecylbenzenesulfonate, the solid matter was separated by filtration, washed with water and dried to obtain a cyan magnetic toner.

[0023]

EFFECTS OF THE INVENTION The present invention is as described above, and since the core material containing magnetic particles as a main component is coated with an inorganic metal compound having a high refractive index, the color of the core material can be hidden. it can. Further, when a colored layer is coated on the periphery thereof, an encapsulated magnetic toner having a vivid color can be obtained, so that a color magnetic toner used for electrophotographic toner, magnetography toner, magnetic ink for various magnetic printing. Can be used as Further, by producing a layer of an inorganic metal compound by the method of the present invention, an encapsulated magnetic toner having a uniform particle size and layer thickness can be obtained.

[0024]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an encapsulated magnetic toner of the present invention.

[Explanation of symbols]

 11 Core Material Mainly Containing Magnetic Particles 12 Layer Made of Inorganic Metal Compound

Claims (3)

[Claims] 1. An encapsulated magnetic toner comprising a core substance containing magnetic particles as a main component and a shell substance coating the core substance, wherein the shell substance has at least a layer made of an inorganic metal compound having a high refractive index. An encapsulated magnetic toner characterized by the above. 2. The encapsulated magnetic toner according to claim 1, wherein the inorganic metal compound has a refractive index of 1.9 or more. 3. A core material is dispersed in a dilute solution of a metal salt,
A method for producing an encapsulated magnetic toner, which comprises forming a shell substance by depositing an inorganic metal compound on the surface by a precipitation reaction.