JPS603177B2 - magnetic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses magnetic toner, more specifically, the main component is toner particles only, which is predominantly charged by mutual friction of each toner particle, develops a static latent image, and forms a static image on plain paper. The present invention relates to an improvement in a one-component magnetic toner that does not contain carrier particles and allows a toner image to be obtained by electrotransfer means.

There are two methods for developing an electrostatic charge port image: a dry development method and an overflow development method.

In any of these developing methods, a two-component mixture consisting of a carrier and a toner is usually used as the developer. In development using the two-component developer, the toner is consumed and the carrier is a component that is not consumed. For example, in dry development, when a mixture of these is mechanically stirred sufficiently, the toner becomes charged with the opposite polarity to the carrier. occurs and is charged to a specific polarity, toner particles are attached to the electrostatic latent image and a powder image is obtained. Therefore, as the number of times a two-component developer consisting of toner and carrier is used increases, the mixing ratio of the toner and carrier components changes, and copies with a constant density cannot be guaranteed. need to be replenished.

Furthermore, as the number of mechanical agitation increases, the triboelectric properties of the carrier change, and this change appears as fogging (background stains) on copies, so there are disadvantages such as the need to replace the carrier with fresh carrier. has. In order to eliminate this drawback, a one-component developer containing only toner as a main component and containing no carrier component was proposed. for example,
US Pat. No. 3,639,245 discloses a so-called magnetic toner which is a combination of fine particles of a ferromagnetic material such as triiron tetroxide, a thermoplastic resin such as an epoxy resin, and conductive carbon black. The magnetic toner has eliminated the above-mentioned drawbacks of the two-component developer, but on the other hand, since the magnetic toner has tortoise-conducting properties, it is the most common and easily controllable corona when transferring onto paper, etc. There is a drawback that it is difficult to use a discharger. That is, when the magnetic toner is transferred onto paper using a corona discharger, part or all of the powder image is transferred.
As a result, a good transferred image cannot be obtained. Also,
Magnetic toners containing ferromagnetic fine powder generally have poor fixing properties, and it is known that to improve this, a low melting point resin is used in the resin component of the magnetic toner, or a plasticizer is added. ing.

However, with this method, the fluidity of the toner deteriorates,
In addition, transfer efficiency decreases due to the formation of nodules during storage, or severe master contamination (stains on the surface of the photosensitive material), resulting in fogging and poor durability. As described in Publication No. 17739, it is known that the surface of a powder made of an aliphatic compound and extender pigment or magnetic powder is coated with a resin film, but the surface is coated only with a resin. Therefore, it is difficult to apply an electric charge to the toner, and frictional charging between the toner particles is difficult to occur.As a result, a device for applying an electric charge to the toner is required, making the device complicated.The present invention eliminates these drawbacks of conventional toner. It has been improved as much as possible, and its purpose is to eliminate the need for a carrier.
This is a toner-only developer that is predominantly charged by mutual friction between toner particles, and the toner as a whole is electrically insulating, which is a disadvantage of conductive magnetic toner. A corona discharger is used during transfer. The aim is to provide the best possible toner.

Another object of the present invention is to provide a one-component magnetic toner that is free from master contamination, has high transfer efficiency, is fog-free, and has excellent durability.
3 The present invention has a layer on a core particle made of a low softening point resin, which contains a resin having a higher softening point than the low softening point resin and a substance having a triboelectrification series different from that of the resin and having no compatibility with the resin. , in a one-component magnetic toner containing a magnetic material in at least one of the core particles or the upper layer, the substance having a different triboelectrification series and not being compatible with the resin may be a magnetic powder, an inorganic pigment, an organic pigment, glass, sulfur, copper,
A one-component magnetic toner selected from aluminum and zinc, wherein the substance and/or magnetic material is substantially exposed on the surface of the toner particles, and the entire particle is electrically insulating. - is in In the magnetic toner of the present invention, since the resin forming the coating layer has a high softening point, there is no master contamination and the magnetic toner has high durability.Moreover, a resin with a relatively low softening point is used as the resin forming the core fine particles, and the transfer paper The adhesion to the surface is improved.

Furthermore, in particular, the coating layer contains a substance that is negatively or positively charged by friction and does not mix with the resin, a magnetic substance, or two different substances on the triboelectrification series, and these substances are substantially present on the coating surface. Since the particles are exposed to each other, each toner particle is given a positive or negative charge due to the friction between the particles, and the magnetic material contained therein is attracted by a magnet, forming spikes of toner for development.
Furthermore, since the entire particle is electrically insulating, it has many excellent properties such as the ability to use a corona discharger during transfer. The resin constituting the core fine particles used in the present invention and the substance to be included in the coating layer are substances that are charged by friction with the resin, are well dispersed in the resin, are chemically stable, and have a particle size of less than IA. It is desirable to be able to easily obtain one.

The main ones are as follows.

1 Magnetic powder Manganese, iron, cobalt, nickel, chromium metal powder;
Metal oxides of chromium dioxide, iron sesquioxide, and triiron tetroxide; M'e204 (M is Mn, Co, Ni, Mg, Zn,
Cd) ferrite; alloys containing manganese and copper such as manganese-copper-aluminum, manganese-copper-tin, etc. Alloys that exhibit ferromagnetism through heat treatment. White: Gloss white, barium sulfate, barium carbonate, calcium carbonate, calcium silicate, magnesium silicate, titanium white, zinc lotus, lead white, litobone, zinc sulfide, antimony white, yellow lead, zinc yellow, barium chromate, cadmium yellow, Yellow iron oxide, Huangshi,
Lead cyanamide, calcium leadate, ultramarine blue, navy blue, chrome green, etc., 3 organic pigments Penzyl Yellow, Naphthol Yellow S Lake, Quinoline Yellow Lake, Persian Orange, Fire Red, Resole Red, Lake Red C, Lake Red D,
Permanent Red FR, Alizarin Lake, Heliobord-BL, Bordeaux 1 Fertilizer, Bonmarulite, Thioindigo Maroon, Victoria Blue Lake to Peacock Blue Lake, Phthalocyan Flu, Fast Sky Blue, Indansrenflu-RS, Naphthol Green B, Green gold, aniline black, etc. 4
Other powdered glasses, sulfur, copper, aluminum, zinc, etc.
The resin should be incompatible with the resin used, taking into account triboelectric properties with different substances on the triboelectrification series, manufacturing method and conditions, coatability for the substance, ease of fixation by heat and Z, etc. For example, styrenes such as styrene and parachlorostyrene; Z vinyl esters such as vinylnaphthalene, vinyl chloride, vinyl bromide, pinyl fluoride, vinyl acetate, and vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, Q
-Methyl chloroacrylate, methyl 2-methacrylate, -
Q-methylene aliphatic monocarboxylic acid esters such as ethyl methacrylate, butyl methacrylate dialkylaminoalkyl methacrylate; acrylonitrile;
Vinyl ethers such as methacrylonitrile, acrylamide, vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether; vinyl methyl ketone,
Vinyl ketones such as pinylhexylketone; N-vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyro-trilidone; homo- or copolymers, or mixtures thereof, rosin-modified phenol-formalin resin, epoxy One or more of resins, polyurethane resins, cellulose resins, polytable resins, polycarbonate resins, epoxidized phenol formaldehyde resins, polyolefin resins, and polyamide resins are used.

The resin used for the particle core has a softening point of 40o ~
As the coating layer resin, one having a softening point of 80° to 150q0 and a melting point higher than that of the particle core resin is used.

The mixing ratio of the resin for forming the coating layer and the substance incompatible with the resin varies somewhat depending on the type of material used, but is preferably about 15 to 15 parts by weight per 10 parts by weight of the resin component.

Further, after forming the coating layer in advance, the magnetic powder,
When one or more types of inorganic pigments, organic pigments, and other fine powders are attached and fixed by fusing in a thermal simulant flow, the content can be reduced to about 0 per part by weight of toner 10. .1～
The amount may be 2 parts by weight.

It should be noted that pigments or dyes can be used as colorants in the core particle forming resin and the coating layer forming resin, but conductive substances such as carbon black must be used in small amounts to the extent that they do not impede insulation properties. is necessary. Also, if necessary,
A small amount of a charge control agent for controlling the charge of the toner, other higher fatty acids, plasticizers, metal soaps, higher alcohols, hydrophobic silica, etc. can be used. It is necessary that the specific resistance of the magnetic toner is 1.40 or more, and that the attenuation rate of the potential of the developed developer is less than 50% according to a prescribed measurement method. To measure specific resistance, use yellow steel as the bottom.
The sample was placed in a container 0 with an acrylic resin board as a measuring wall, and a yellow node electrode with a thickness of 4 to 5 skins was applied to the top, and a pressure of lk 9' was applied.
In this method, a voltage of 100 V is applied, and the measurement is performed when the absorbed current has sufficiently decreased and the measured current has become substantially flat. To measure the attenuation rate of the potential of the developer, develop the toner over a fixed area on zinc oxide photosensitive paper, irradiate it with light using a translucent electrometer, determine the initial toner potential, and measure the potential of the toner at the initial stage. The toner potential was measured after minutes had elapsed, and the difference between the two values was expressed as a percentage. The core particles in the present invention may be heated and kneaded using a kneading machine consisting of two rolls, cooled, and finely pulverized using a hammer mill as shown in the examples.
It can also be produced, for example, by the fog drying method shown in US Pat. No. 3,338,991.

To coat the surface of the fine particles produced in this way, for example, a solvent is added to the above-mentioned ratio of high melting point resin and magnetite fine powder, magnetite is dispersed in the resin solution, and the mixed dispersion is atomized in a heated air stream. Obtained by drying. The thickness of the coating layer is preferably 0.5 to 2.0. 0
In addition to the above-mentioned manufacturing method, for example, finely pulverized toner intermediates may be dispersed in a high softening point resin solution and then spray-dried, or toners coated with a resin layer may be produced using encapsulation technology. After obtaining the intermediate, one or more of magnetic powders, inorganic pigments, organic pigments, and other fine powders are added, dry mixed, and adhered to the surface of the toner intermediate, and then heated and melted in a heated air stream. It can also be obtained by attaching and fixing.

Example 1 Parts in the following examples indicate parts by weight.

Core particle composition Epicoat 1004 (epoxy resin manufactured by Shell Chemical Co., Ltd.)
4 parts triiron tetroxide (BL-500 manufactured by Titan Kogyo Co., Ltd.) 45 1 Dye (Oil Black BS manufactured by Orient Chemical Co., Ltd.)
1.5DOP
2.5 Coating layer composition Epicoat 1007 (manufactured by Shell Chemical Co., Ltd.) 1.
L-100) 5 Dye (Oil Black BS manufactured by Orient Chemical Co., Ltd.) 1 core particles were melted and mixed in a pressure kneader, cooled, and then finely pulverized in a hammer mill.

Also, the second coating layer is toluene/acetone (8/2)
Add 20 parts of Miyako resin, triiron tetroxide, and 16 parts of dye to the liquid, and finely disperse the mixture using a ball mill. Add 9 parts of core particles to the liquid and disperse with an ultrasonic dispersion machine. The powder was dried using a spray dryer. This was used in a classifier manufactured by Alpine 2 to obtain a magnetic toner of 5 to 20 particles. In the obtained toner, triiron tetroxide was exposed on the surface. Furthermore, 0.2 weight percent of hydrophobic silica Aerosil R-972 (manufactured by Nippon Aerosil Co., Ltd.) was added to the toner.
3 Examples 2 Nuclear particle composition Epikote 1002 (manufactured by Shell Chemical Co., Ltd.) 52 parts Metallic iron powder 4 Base part Carbon black MA-100 (manufactured by Mitsubishi Kasei Co., Ltd. 3)
5 parts zinc stearate
3 parts Coating layer composition/・immer SBM (styrene resin manufactured by Sanyo Kasei Co., Ltd.) 15 parts glass powder 1 part Base part Varifast Mottling 04 (pigment manufactured by Orient Chemical Co., Ltd.)
One part of the core particles was melt-kneaded using a pressure kneader, cooled, and then finely ground using a hammer mill.

The coating layer was prepared by adding 26 parts of the above coating layer composition to 20$ ligroin and dispersing the mixture in a ball mill for 2 hours. 100 parts of the core particles were added to this dispersion, and while being dispersed using an ultrasonic disperser, the mixture was dried using a spray dryer (manufactured by Niro Corporation). Glass powder was exposed on the surface of the obtained toner. The resulting toner was coated with hydrophobic silica Aerosil R9.
72 (manufactured by Nippon Aerosil Co., Ltd.) was added in an amount of 0.2% by weight, and a magnetic toner of 5 to 20 μm was obtained using a zigzag classifier. Further, 0.5% by weight of hydrophobic silica was added to a resin-coated toner prepared in the same manner as above except that the glass powder was removed from the coating layer composition, and the mixture was thoroughly mixed in a dry method.

Use a spray dryer to dry this at an inlet temperature of 250 pm.
The treatment was carried out at a rate of 15 minutes in a hot air stream with an outlet temperature of 50°C. 0.1% by weight of hydrophobic silica was added to this, and a magnetic toner having a particle size of 5 to 20 mm was obtained using a zigzag classifier. The two types of magnetic toners obtained had excellent heat-resistant storage stability and fixing properties compared to single-layer magnetic toners.

In addition, 0-Bix 200 plate electronic copying machine (Konishi Roku Photo Industry ■
When the image was evaluated using a selenium photoreceptor, the image was clear with no fog.

Example 3 Nuclear particle composition Epicote 1002 (manufactured by Shell Chemical Co., Ltd.) 4 Foundation part Evaflex 210 (manufactured by Mitsui Polychemical Co., Ltd.)
1.Foundation: triiron tetroxide
45 parts carbon black
3 parts calcium stearate 2 parts Coating layer composition Styrene (95 mol%) dimethylaminoethyl methacrylate (5 mol%) copolymer (softening point 125°C)
1.Foundation: triiron tetroxide
15 parts of the core particle composition were mixed and melted and kneaded in a pressure kneader. After cooling, the Oka-shaped material was pulverized with a hammer mill.

Separately, for the coating layer, add 25 parts of the coating layer composition to 200 parts of ligroin, disperse the magnetic powder in the resin for 2 hours using a ball mill, and add 10 parts of the core particles prepared earlier to this dispersion. The mixture was dispersed using an ultrasonic dispersion machine and then dried using a spray dryer. Triiron tetroxide was exposed on the surface of the obtained toner. 0.3% (by weight) of hydrophobic silica was added to the obtained powder, and the powder was subjected to zigzag classification to obtain magnetic toners of 5 to 201. Example 4 Core particle composition Epiquat 1002 5 parts Triiron tetroxide 45 parts Carbon black 5 parts Coating layer composition Epiquat 1007 (manufactured by Shell Chemical Co., Ltd.) 15 parts Aniline black 7.5 parts Produced in the same manner as in Example 1 .

Example 5 Core particle composition Styrene (70 mol%)-butyl methacrylate (30 mol%)
(mol%) copolymer (softening point 9yo) 95 parts Carbon black 5 parts Coating layer composition Epicoat 1007 2 Base part Manganese-copper-aluminum alloy powder 2 parts Core particles were prepared in the same manner as in Example 1, and the coating layer was The coating layer composition was added to 200 parts of methyl cellosolve solvent in a ball mill, dissolved and dispersed for 3 hours, and 6 pieces of the above-mentioned core particles were added thereto.
The mixture was dispersed using an ultrasonic dispersion machine and then dried using a spray dryer.

The manganese-copper-aluminum alloy powder was exposed on the surface of the obtained toner. This is Aerosil R-9
72 (manufactured by Nippon Aerosil Co., Ltd.) was added in an amount of 0.1% (by weight), and the particles were classified into particle sizes of 5 to 20 particles. The magnetic toners obtained in Examples 3, 4, and 5 all had excellent heat-resistant storage stability and fixing properties compared to single-layer magnetic toners. Also,
When we evaluated images using a zinc oxide photoreceptor using an experimental machine that had been modified from the developing part of a U-BIX80 U-BIX copier (manufactured by Konishiroku Photo Industry Co., Ltd.), we found that the surface of the zinc oxide photoreceptor was not contaminated. Even after repeated development and transfer, a clear copy image without fogging was obtained on the white paper.

Furthermore, when a large number of copies were obtained by repeatedly replenishing the magnetic toner, good results were obtained with no change in image density or image quality.

Claims (1)

[Claims] 1. On the core particle made of a low softening point resin, there is a layer containing a resin having a higher softening point than the low softening point resin and a substance that has a different triboelectrification series and is not compatible with the resin, and the core particle or In a one-component magnetic toner in which at least one of the upper layers contains a magnetic material, the material that has a different triboelectric charge series and is not compatible with the resin is magnetic powder, inorganic pigment,
selected from organic pigments, glass, sulfur, copper, aluminum, and zinc; the substance and/or magnetic material is substantially exposed on the surface of the toner particles; and the entire particle is electrically insulating. Characteristic one-component magnetic toner.