JPS5825643A - Magnetic toner - Google Patents

Abstract

PURPOSE:To provide a magnetic color toner superior in fixability, by coating fine magnetic particles with a white pigment, and further with a lake pigment, and using a magnetic toner containing this powder. CONSTITUTION:15-100pts.wt. magnetic powder is contained in 100pts.wt. binder resin,such as polystyrene, polychlorostyrene, or polyvinyl butyral, and this powder is coated with 5-50pts.wt. white pigment (per 100pts.wt. fine magnetic particles, such as iron, nickel, Fe2O3, or gamma-Fe2O3) having white opaque crystals and capable of coating a magnetic material by solution reaction or heat treatment, such as zinc oxide or titanium oxide. This coated powder is further coated with 5-50pts.wt., preferably 10-40pts.wt., lake pigment prepared with a lake- forming agent for use in an acidic dye, such as aluminum or barium salt, or with lake-forming agent for use in a basic dye, such as phosphomolybdic or phosphotungstic acid to obtain a magnetic color toner.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner for developing latent images in electrophotography, electronic printing, electrostatic recording, magnetic recording, etc., and particularly relates to magnetic color toner.

J Electrophotography, a method that forms an electrostatic latent image by utilizing the properties of photoconductors such as cadmium sulfide, polyvinylcahalbazole, selenium, and zinc oxide. image exposure to form an electrostatic latent image, which is then developed with toner powder charged to the opposite polarity to that of the electrostatic latent image, and further transferred to a transfer sheet and fixed as necessary. It's a method.

The electronic printing method, as proposed in Japanese Patent Publication No. Sho 42-14342, is a method of guiding and fixing a charged powder toner onto a recording material using a field for printing.

The electrostatic recording method applies charges to the dielectric layer in the form of an image.
This is a method of attaching charged toner powder to it and fixing it.
Similarly, the magnetic printing method is a method in which a magnetic latent image is formed on a recording material, developed with toner powder containing a magnetic material, transferred to a transfer material, and fixed.

In the development system of the above process, in the method using -component magnetic toner, the toner is conveyed by a magnetic roll to form a magnetic brush, and the magnetic brush comes into contact with a photoconductor such as cadmium sulfide or an insulating electrostatic charge carrier. The charge on the holder and the induced static electricity or frictional static electricity held by the toner are attracted, and the toner adheres to the electrostatic charge holder, thereby performing development.

This developing method using a one-component magnetic toner does not require a device to maintain a constant toner concentration in the developer, which is required in two-component developing methods using carrier particles, and the developing device is simplified. , it is advantageous in terms of low cost or miniaturization.

On the other hand, recently, as the purposes of use have become more diverse, there has been a desire for a compact and inexpensive multi-color copying machine that can produce images of desired colors as required. However, even if a coloring agent is added to the binder resin, the color of the magnetic material cannot be hidden, so it is difficult to whiten or color the magnetic material.
It has been proposed in No. 42539, No. 51-46131, etc. However, the above method was insufficient to hide the color tone of the magnetic material and obtain an image with the desired color. In order to hide the color tone of the magnetic material, it is possible to reduce the amount of magnetic material in the toner or increase the amount of colored pigment, but if the amount of magnetic material is reduced too much, developability will deteriorate and the amount of colored pigment will be reduced. If the amount of the toner is increased too much, a problem arises in that the developability or fixing property is deteriorated.

An object of the present invention is to provide a richly colored magnetic color toner that sufficiently hides the color tone of the magnetic material.

A further object of the present invention is to provide a magnetic color toner in which the image density is high, the image is clear, and there is little fog.

A further object of the present invention is to provide a magnetic color toner with excellent fixing properties.

Its characteristic feature is a magnetic toner containing magnetic fine particles coated with a white pigment and further coated with a lake pigment.

A more preferred embodiment of the present invention is a magnetic toner co-containing a small amount of magnetic powder and a binder resin, in which the magnetic powder is added in an amount of 15 to 100 parts by weight (20 parts by weight) per 100 parts by weight of the binder resin. ~80 parts by weight), and the magnetic powder is coated with 5 to 50 parts by weight (preferably 10 to 40 parts by weight) of a white pigment based on 100 parts by weight of the magnetic fine particles, and further coated with 5 to 50 parts by weight (preferably 10 to 40 parts by weight). is a magnetic color toner coated with 10 to 40 parts by weight of lake pigment.

The white pigment used in the present invention has white opaque crystals that can be coated with a magnetic material by melting, solution reaction, heat treatment, etc.
For example, zinc oxide, titanium oxide. Lake dyes forming the lake pigment used in the present invention are mainly acidic dyes and basic dyes.

An acidic dye is a dye acid having an acidic group such as a sulfonic acid group or a carboxyl group in the molecule, for example, 0.1.
Ac1d Yellow 1, C! , 1. A
c1d Yellow7, O, 1, Ac1d Y
yellow 36, O, 1, Ac1d Yellow
ow70, 0.1. Ac1d Orange 1
, O,1, Ac1d Orange7, O,1,
Ac1d Orange 45. O,1,Ac1d
Red 1°0.1. Ac1d Red 14.
O, 1, Ac1d Red 26°0.1. Ac1d
Violet 15, O, L Ac1d Blu
e1.

0.1. Ac1d Blue 7, O, 1, A
c1d Blue 9, O, I.

Ac1d Green 3, O, 1, Ac1d G
reen 9, O, 1, Ac1dGreen 4
1, etc.

Basic dyes have an amino group and its derivatives in the molecule, and their structural skeletons include sidiphenylmethane, triphenylmethane, xanthine, oxazine, and thiazine. For example, C1, Ba5ic Yellow
ow1, O,1,Ba5ic.

Yellow 2, C, 1, Ba5ic Ora
nge 14, O,I.

Ba5ic'Red 1, 0.1. Ba5ic
Red 12.0. I.

Ba5ic Violet 1, 0.1. Ba5i
c Violet 3, O, I.

Ba5ic Violet 10. O,1,Ba5
ic Blue 1. O, I.

Ba5ic Blue 5, O,1,Ba5ic
Blue 7. O,T.

Ba5ic Green 1, 0.1. Ba5ic
Green 4 etc.

The lake forming agents used in producing the lake pigment used in the present invention include metal salt compounds such as aluminum salts, calcium salts, and barium salts for acid dyes, and phosphomolybdic acid and phosphorus compounds for basic dyes. Acids include tungstic acid and gallic acid.

The magnetic fine particles used in the present invention include iron, nickel,
Fe, O,, 1-Fe, 039 There are various ferrites, etc., but in terms of residual magnetization, cost, color tone, etc., γ-Fe, 039
．． is favorable, and the average particle size is 0.0 when observed with an electron microscope.
It is 1 to 1.0μ (preferably 0.03 to 0.4μ).

The colored magnetic powder used in the present invention can be produced by various known methods, but the following method is preferred, for example. After dispersing magnetic fine particles in an aqueous solution containing metal ions that form a white pigment, a precipitant is added to the aqueous solution and the precipitant and the metal ions are reacted to form a water-insoluble compound. is precipitated on the surface of the magnetic fine particles. Thereafter, the coated magnetic fine particles are filtered and dried. Furthermore, after dispersing the obtained magnetic fine particles coated with the white pigment in an aqueous solution of a lake dye, a lake forming agent is added to the aqueous solution, and the lake pigment is applied to the surface of the magnetic fine particles coated with the white pigment. is precipitated.

Thereafter, the magnetic fine particles double-coated with white pigment and lake pigment are filtered and dried.

As the binder resin used in the toner of the present invention, a wide variety of binder resins including those known in the art can be used, including the following. Polystyrene, chlorophoristyrene, poly-α-
Methylstyrene, styrene-chlorostyrene copolymer,
Styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-
Vinyl acetate copolymer, styrene-maleic acid copolymer,
Styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate) copolymers, etc.), styrene-methacrylic acid ester copolymers (styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-butyl methacrylate copolymers, methacrylate-phenyl methacrylate copolymers) tJt polymers, etc.), styrene-based polymers such as styrene-α-methyl chloroacrylate polymers, styrene-acrylonitrile-acrylic acid ester copolymers (styrene or monopolymers or copolymers containing styrene substitutes), Vinyl chloride resin, ethylene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenyl resin,
Examples include epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, and polyvinyl butyral resin.

The above-mentioned 41j fats are not limited to being used alone, but can also be used in combination of two or more.

A coloring agent may be added to the toner of the present invention if necessary, and examples of such coloring agents include yellow lead, cadmium yellow, mineral first yellow, navel yellow, naphthol yellow SN Hansa yellow G.
, Permanent Yellow NOG, Tartradisi Lake,
Red yellow lead, molybdenum orange, permanent orange GTJ pyrazolone orange, benzine orange G1 cadmium red, permanent orange)" 4 T (,,
Watching Red Calcium Salt, Eosin Lake, Brilliant Carmine 3B.

Manganese Purple, Fast Violet B1 Methyl Violet Lake, Deep Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast Sky Blue, Indan Stremburu-BO
, chrome green, chromium oxide, pigment green B
1 Malachite Green Lake, Final Yellow Green G, etc. The amount of the additive must be 20 parts by weight or less (particularly less than 10 parts by weight of the binder resin) based on 100 parts by weight of the binder resin.

Additives may be mixed into the toner of the present invention as necessary, and examples of such additives include lubricants, fixing aids, such as low molecular weight polyethylene, fluidity imparting agents, and anti-caging agents, such as low molecular weight polyethylene. These include colloidal silica.

Developing a latent image using the toner of the present invention is described in U.S. Pat. ? , Method using conductive magnetic toner described in Specification No. 58 l°, JP-A-54-42
No. 141, No. 55-18656 1 (methods using insulating magnetic toner described or methods using high-resistance magnetic toner, etc.).
A method using an insulating toner described in Publication No. 42141 and No. 55-18656, that is, an electrostatic image carrier that holds an electrostatic image on its surface and a developer that carries an insulating magnetic developer on its surface. The insulating magnetic developer is supported on the developer carrier at a thickness thinner than the gap, and the electrostatic charge is applied to the insulating magnetic developer under the action of a magnetic field. Particularly preferred is a method in which the image is transferred to an image carrier and developed.

The method for coloring magnetic powder will be described in detail below in production examples.

[Production Example 1] 1O1 of water kept at 25°C in a nitrogen atmosphere! γ-Feρ3 (50?) with an average particle size of 0.2μ was stirred with a stirrer (5
00r, p, m) Disperse while using L. After that, 25℃
Titanium tetrachloride 151 kept at 0.5? After dropping at a dropping rate of /min, the mixture was filtered in a nitrogen atmosphere, left to stand for 24 hours, and then dried in air at 150° C. for about 1 hour. Approximately 63
A white magnetic powder treated with titanium oxide (11) was obtained.

60℃ water! Inside 0.1. Ba5ic T(zd
1 (507) is completely dissolved and the above white magnetic powder (6
Disperse (1) while stirring with a stirrer (500 r, p, m).

Thereafter, this dispersion was stirred and heated to 60°C.
0.05 M phosphorous tungsten molybdic acid aqueous solution kept at ℃ 21! was added dropwise at a rate of 100 me/rni, stirring was continued for 10 minutes, and the resulting lake was filtered off, washed with water, and dried in air at 40°C to obtain magnetic powder coated with red lake pigment.

t; The resulting white pigment and red pigment are doubly coated. The magnetic powder used was 751.

[Production Example 2] 1-Fet03 (509) used in Production Example 1 was dispersed in a 0.01M zinc chloride aqueous solution 101 kept at 25°C with stirring. Thereafter, a 0.02 M sodium hydroxide aqueous solution 101 kept at 25°C! 100m1/mi
The mixture was added dropwise at a rate of n and after complete addition, stirring was continued for 20 minutes, followed by filtration, washing with water, and drying to obtain magnetic powder coated with zinc hydroxide. Thereafter, it was left in air at 150° C. for 2 hours to obtain white magnetic powder coated with zinc oxide. The obtained zinc oxide treated magnetic powder had a particle size of 652.

25℃ water 11! Inside O, 1, Ac1d Red 1
(50f) was completely dissolved, and the above white magnetic powder (601
i') was dispersed in the same manner as in Production Example 1. Then 25℃
0.51 of a 0.1 M barium chloride aqueous solution held at 10
After complete dropwise addition at a rate of 0 ml/min, stirring was continued for 10 minutes and the same procedure as in Production Example 1 was carried out to obtain 74f of red magnetic powder.

[Production Example 3] 0, 1. Ac1d Red (50f) as O, 1,
The binding was carried out in the same manner as in Production Example 2 except that Ac1d Blue 9 (6(1) was used), and a blue-coated magnetic powder (729) was obtained.

[Production Example 4] 0, 1. Ac1d Rzd is 0.1. Ac1d G
The procedure was carried out in the same manner as in Production Example 2 except for changing to reen 3. As a result, magnetic powder coated with green color (78F) was obtained.
was gotten. Examples of magnetic color toner production are shown below.

[Example 1] The above mixture was kneaded with a roll mill at 150°C, cooled, and then coarsely ground with a speed mill. Thereafter, it was finely pulverized using a jet mill, and a red magnetic toner having a size of 5 to 20 μm was obtained using an air classifier.

Images were produced using this red magnetic toner using the apparatus shown in FIG. 1 in the following manner. A negative electrostatic latent image is formed on a well-known salivary lead oxide photoreceptor, and the sleeve is fixed to a rotating magnet with a sleeve surface magnetic flux density of 700 Gauss and a distance between the ear cutting blade and the sleeve surface of 0.2 as shown in Fig. 1. (The circumferential speed of the sleeve is the same as that of the drum, but the direction of rotation is opposite.) The developing device was set at a distance between the photosensitive drum surface and the sleeve surface of 0.25 mm, and the sleeve was heated at 1.2 KHzl and 2 KV.
The powder image was developed using the red magnetic toner by applying an alternating current of 150 V and a direct current bias of -150 V, and then the powder image was transferred while irradiating a direct current corona of 17 KV from the back side of the transfer paper to obtain a copied image. The remaining developer on the photosensitive drum was removed using a magnetic brush cleaner, and fixing was carried out using a commercially available plain paper copying machine (trade name: NP-200J, manufactured by Canon). The resulting image has a clear red color,
It was clear and had no fog, and had good fixing properties.

[Example 2] The above mixture was made into a toner in the same manner as in Example 1. As a result, a clear red image with a color that sufficiently concealed the tone of the magnetic powder and with little fogging was obtained. The anchorage in the trench was also good.

[Example 3] The same procedure as in Example 2 was carried out except that the red magnetic powder (Production Example 2) was replaced with the blue magnetic powder (Production Example 3). As a result, the color tone, image quality, and fixability were all good. .

[Example 4] The same procedure as in Example 2 was performed except that the red magnetic powder (Production Example 2) was replaced with the green magnetic powder (Production Example 4). As a result, the color tone, image quality, and fixability were all good. .

[Comparative Example 1] In Example 1, instead of using the red magnetic powder obtained in Production Example 1, magnetic powder 609 coated with the white pigment obtained in the process of Production Example 1 and the white pigment coated in Production Example 1 were used. Example 1 was carried out in the same manner as in Example 1, except that the same amount of red pigment as in the case where the coated magnetic powder was coated with red lake pigment was mixed into the binder resin. As a result, the image quality and fixing properties were good. However, a sufficiently good red image could not be obtained.

[Comparative Example 2] The same procedure as in Example 1 was carried out except that instead of the red magnetic powder (Production Example 1), magnetic powder coated only with red pigment was used. As a result, the image quality and fixing properties were Although the results were good, a good red image could not be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a developing process to which the toner of the present invention can be applied. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 2... Non-magnetic cylinder, 3... Magnetic roll, 4-... Hopper, 5-... Doctor blade, 6... Magnetic color toner.

Claims (1)

[Scope of Claims] A magnetic toner comprising magnetic fine particles coated with a white pigment and further coated with a lake pigment [7].