JPH04296868A - Color magnetic toner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to toner for magnetic recording, and more particularly to a microencapsulated color magnetic toner capable of producing clear color images.

0002

[Prior Art and its Problems] Conventionally, in magnetic recording methods, 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. A visible image is formed using the following methods.

The magnetic toner used here is generally known to be one obtained by kneading magnetic particles such as magnetite, gamma ferrite, barium ferrite, etc. with a polymer and a coloring agent, and then pulverizing the mixture. However, since conventional magnetic toners simply mix black or blackish-brown magnetic particles with a colorant, the toner becomes cloudy and a color toner with a clear color cannot be obtained. For this reason, color images formed using conventional magnetic toners have low brightness and are often cloudy.

0004

SUMMARY OF THE INVENTION The present invention relates to conventionally known magnetic recording toners, and an object of the present invention is to provide a microencapsulated color magnetic toner suitable for obtaining clear color images.

[0005]

[Means for Solving the Problems] The present invention has been made to achieve the above object, and provides a microencapsulated color magnetic toner comprising a core material and a shell material.
The core material has at least magnetic particles and a colorant, the shell material comprises one or more polymers, and the shell material contains a microencapsulated color magnetic toner having pores capable of releasing liquid inclusions upon application of heat. This is what we provide.

In a preferred embodiment of the present invention, the magnetic particles used in the present invention preferably have an average particle diameter of 1 μm or less. Further, the colorant of the present invention is preferably in a liquid state during thermal transfer.

The present invention will be explained in detail below using the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention. Figure 1
In this embodiment, a core material 1 mainly composed of magnetic particles 2 and a colorant 3 is encapsulated in a shell material 4 made of a polymer. As the magnetic particles 2, a single magnetic particle, a mixture of several types of magnetic particles, or a mixture of magnetic particles and a polymer can be used. For example, ferromagnetic metals such as magnetite, ferrite, iron, cobalt, and nickel, or alloys or compounds containing these elements are used. In this case, the magnetic particles may be subjected to surface treatment such as silane coupling treatment in order to increase their affinity with colorants and the like. In addition, when using a mixture consisting of magnetic particles and a polymer, the above-mentioned magnetic particles and polymer are kneaded and then pulverized, or the monomer in which the magnetic particles are dispersed is subjected to emulsion polymerization, suspension polymerization, dispersion polymerization, etc. A method such as polymerization using In this case, the polymer is preferably crosslinkable. The magnetic particles can be used as long as they have a size of several microns or less, but are preferably in the range of several hundred angstroms to 1 micron.

The colorant 3 is not particularly limited in the present invention, and various known dyes such as those used in process inks and electrostatic photographic toners can be used by dissolving them in a solvent.

[0009] The core material 1 also contains magnetic particles 2 and a coloring agent 3.
In addition to the main component, it is preferable to include a binder in order to fix the colorant to the transferred object during transfer. The binder may be a commonly used organic polymer such as acrylic resin, methacrylic resin, styrene resin, alkyd resin, polyolefin resin, cellulose ether resin, urethane resin, synthetic rubber, natural resin, or a polymer blend or copolymer resin thereof. The molecules can be used by dissolving them in a solvent.

Furthermore, by covering the core material 1 with a shell material 4 made of polymer, a microencapsulated toner can be obtained. Examples of the shell material 4 include commonly used resins such as acrylic resins, methacrylic resins, polystyrene, polyester resins, polyurethane resins, polyurea resins, polyamide resins, epoxy resins, natural resins, etc. Alternatively, it is also possible to use a mixture of two or more kinds.

Methods for producing the above-mentioned shell material include a phase separation method in which a concentrated phase of the polymer is separated around a core material dispersed in a polymer solution, a polymer hardening test drug distributed around a core material in a polymer solution, etc. In-situ polymerization method, in which monomers and polymerization catalysts are supplied from either the inner phase or outer phase of the emulsion in which the core material is dispersed, and the surface of the core material is coated with polymer. Microencapsulation techniques such as interfacial polymerization in which the monomer is supplied from both the internal and external phases of the emulsion in which the substance is dispersed are preferred, but are not limited to these methods.

In particular, by using an interfacial polymerization method in which polymerizable monomers are supplied from both the inner and outer phases of an emulsion in which magnetic particles as a core substance and a colorant solution are uniformly dispersed, the particle size can be reduced. A complete set of microencapsulated color magnetic toners can be produced. Suitable polymerizable monomers used here include acrylic esters, methacrylic esters, styrene and its derivatives, isocyanates, various amines, and compounds having epoxy groups.

Furthermore, the shell material of the present invention, upon application of heat,
Since it has pores that can release liquid inclusions, only liquid colorant is transferred to the transfer target, which is preferable. In order for the shell material to have pores, the characteristics of the shell material are important.
Although resins made of polyvalent isocyanate and polyol are preferred, the formation of pores can be achieved even with other resins by reducing the film thickness or by manufacturing by in-situ polymerization or interfacial polymerization.

[0014]

[Operation] The above-mentioned microencapsulated color magnetic toner develops a magnetic latent image due to the magnetism of the magnetic particles contained in the core material. Of the magnetic particles that are the core material and the coloring agent, only the liquid coloring agent passes through the pores of the shell material and is transferred to the transferred object during thermal transfer, resulting in clear color images that are not affected by the color of the magnetic particles. can get.

[0015]

[Examples] The present invention will be specifically explained below using examples. <Example 1> 50 parts by weight of magnetic particles with an average particle size of 0.05 μm subjected to silane coupling treatment, 30 parts by weight of yellow process ink, 20 parts by weight of phenol-modified alkyd resin, xylylene diisocyanate and trimethylolpropane A mixture of 10 parts by weight of the adduct, 5 parts by weight of ethyl acetate, and 20 parts by weight of dibutyl phthalate was added to 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 were dispersed, using a homogenizer. Rotation speed 10000rpm using
The particles were dispersed for about 5 minutes so that the average particle size was 10 μm. While stirring the obtained dispersion at a rotation speed of 500 rpm, the temperature was raised to 60° C., and a polymerization reaction was carried out for 5 hours. After the reaction, add hydrochloric acid to decompose and remove colloidal calcium phosphate and sodium dodecylbenzenesulfonate.
The solid matter was filtered off, washed with water, and dried to obtain a yellow magnetic toner for magnetic recording. Using the obtained yellow magnetic toner, a magnetic latent image was developed using a magnetic recording device, and this was thermally transferred to coated paper, thereby obtaining a clear yellow visible image.

<Example 2> 50 parts by weight of magnetic particles with an average particle size of 0.05 μm, subjected to silane coupling treatment,
Watching Red ethylene glycol dibutyl ether solution 30 parts by weight, phenol-modified alkyd resin 2
0 parts by weight of ethylene glycol dimethacrylate, 3 parts by weight of lauroyl peroxide, 5 parts by weight of colloidal calcium phosphate and 0.1 parts by weight of sodium dodecylbenzenesulfonate were dispersed in 10 parts of water.
00 parts by weight using a homogenizer at a rotational speed of 100.
The particles were dispersed for about 5 minutes at 00 rpm so that the average particle size was 10 μm. While stirring the obtained dispersion at a rotation speed of 500 rpm, the temperature was raised to 80°C, and the polymerization reaction was carried out for 10 minutes.
Time went. After the reaction, hydrochloric acid was added to decompose and remove colloidal calcium phosphate and sodium dodecylbenzenesulfonate, and solid matter was filtered off, washed with water, and dried to obtain a magenta magnetic toner. The obtained microencapsulated magenta magnetic toner can be used as a magenta toner for magnetic recording.

<Example 3> 50 parts by weight of magnetic particles with an average particle size of 0.05 μm, subjected to silane coupling treatment,
A mixture of 30 parts by weight of Samaron Blue ethylene glycol dibutyl ether solution, 20 parts by weight of maleic acid-modified polypropylene, and 20 parts by weight of diphenylmethane-4,4'-diisocyanate was mixed with 5 parts by weight of colloidal calcium phosphate.
Part by weight and sodium dodecylbenzenesulfonate 0.1
In 1000 parts by weight of water in which parts by weight were dispersed, the average particle size was 10 at a rotation speed of 10,000 rpm using a homogenizer.
It was dispersed for about 5 minutes so that the particle size was .mu.m. Thereafter, 10 parts by weight of xylylene diamine was added. The resulting dispersion was reacted at room temperature for 2 hours while stirring at a rotation speed of 500 rpm. Furthermore, the temperature was raised to 60°C, and the polymerization reaction was carried out for 8 hours. After the reaction, hydrochloric acid was added to decompose and remove colloidal calcium phosphate and sodium dodecylbenzenesulfonate, and the solid matter was filtered off, washed with water, and dried to obtain a cyan magnetic toner for magnetic recording. The obtained microencapsulated cyan magnetic toner can be used as a cyan toner for magnetic recording.

[0018]

Effects of the Invention The present invention is as described above, and among the core material containing magnetic particles and a colorant, only the colorant that can pass through the pores of the capsule membrane is transferred to the transferred object during thermal transfer. As a result, clear color images without turbidity caused by magnetic particles can be obtained.

[0019]

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the microencapsulated color magnetic toner of the present invention.

[Explanation of symbols]

1 Core substance 2 Magnetic particles 3 Coloring agent 4 Shell material

Claims (3)

[Claims] 1. A microencapsulated color magnetic toner comprising a core material and a shell material, the core material having at least magnetic particles and a colorant, the shell material comprising one or more types of polymer, and the shell material comprising at least one type of polymer. A microencapsulated color magnetic toner characterized by having pores capable of releasing liquid inclusions when heat is applied. 2. The microencapsulated color magnetic toner according to claim 1, wherein the magnetic particles have an average particle size of 1 μm or less. 3. The microencapsulated color magnetic toner according to claim 1, wherein the colorant is liquid during thermal transfer.