JPH0460645A - magnetic color 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 [Technical Field] The present invention relates to a dry toner for developing electrostatic latent images in electrophotography, electrostatic recording, electrostatic printing, etc., and more particularly to a magnetic color toner.

[Prior art]

As a means for developing an electrostatic image formed on an electrophotographic photoreceptor or an electrostatic recording medium, (1) a pigment or a pigment is added to a binder resin.
(2) A method in which development is performed using only toner in which a magnetic material or the like is dispersed, that is, a one-component development method, and (2) a method in which development is performed using a developer mixed with toner and a magnetic carrier, that is, a two-component development method, are generally adopted. However, in recent years, the -component development method has attracted attention because it has advantages over the two-component development method in terms of equipment simplification, improved reliability, etc.

By the way, the toner of the -component development method can be further divided into magnetic toner and non-magnetic toner, but due to reasons such as the simple replenishment mechanism and the ease of uniformity of the toner layer on the developing sleeve, Single-type magnetic toners are more commonly used.

On the other hand, with the spread of electrophotography, the demand for printing color images in addition to black and white images has increased in recent years.

However, the magnetic material used in conventional magnetic toner is a black or dark brown inorganic magnetic material such as ferrite or magnetite.

Conventional color magnetic toners made of resins, colorants, etc. produce color tones that are blackish, making it impossible to produce clear color images.

Also, in the two-component development system, from the viewpoint of preventing toner scattering, it is desired that color toners be made into magnetic toners.

Therefore, although various proposals have been made to make color toners magnetic, none of them are currently fully satisfactory.

For example, γ-Fe20 whose magnetic particles have a reddish-brown color
．． used as toner from red to brown (JP-A-58-16248, 58-98740, 58-
No. 179846, No. 58-189648, No. 58-187
949, 58-189648, etc.), but γ-F
e20. Because of its strong coloring power as a reddish-brown material, it is not possible to make color toners with high brightness such as yellow.

In addition, methods have been proposed in which the periphery of magnetic particles is coated with white pigments, coloring materials, etc.
73353, etc.), these methods are insufficient to hide the color tone of the magnetic particles, and also do not meet the various requirements for toners (development/cleaning characteristics, durability, environmental stability, etc.). and not getting enough. Also,
A method has also been proposed in which the particle size of the magnetic particles is increased and the coloring power of the magnetic particles is decreased (Japanese Patent Laid-Open No. 187-1987).
No. 951, No. 58-217945, No. 59-170847
No. 59-170848, etc.), even if uniform dispersion is attempted due to crosstalk, variations occur in the composition distribution of the toner after pulverization and classification.
Since toner with a large amount of magnetic material and toner with a small amount of magnetic material are produced, problems such as a decrease in resolution and durability occur.

Furthermore, regarding transparent magnetic particles, yttrium iron garnet (Japanese Unexamined Patent Publication No. 53-118051) and yttrium gallium garnet material (Japanese Unexamined Patent Publication No. 63-50856) are used.
However, the above-mentioned magnetic material is a single crystal magnetic material grown using a specified advanced epitaxial crystallization technology, and the purchase cost is extremely high, and in order to use it as a toner, it must be crushed. and must be pulverized. It also has the disadvantage that pulverization causes distortion in the crystals, deteriorating magnetic properties, and that it is difficult to pulverize particles with a particle size of l/JI11 or less and to make the particle size distribution uniform. Furthermore, since the expensive single-crystal magnetic material must be further pulverized to produce a product, there is also the drawback that the cost is high. In addition, as for the actual properties, yztrium iron garnet has.

Some materials have a saturation magnetic moment of 26 elIu/g, but this material has low light transmittance. In addition, amorphous ferromagnetic materials such as yttrium iron garnet containing metals such as Bi, Ga, Gd, Tb, AQ, Dy, etc. (Japanese Patent Application Laid-open No. 1983-73549) have been proposed, but they have good translucency. It was not possible to have both sex and magnetism at the same time.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned state of the prior art, and uses a magnetic color toner that provides a clear color image, can be uniformly deposited on a developing sleeve, and has excellent uniformity with little toner scattering. The purpose is to provide.

[Means to solve the problem]

As a result of extensive studies, the inventors found that the average particle size was 5 to 8.
The inventors have discovered that a sharp magnetic color toner can be obtained by incorporating the following spinel ferrite fine powder having a particle size of 0 mμ in a binder resin together with a colorant, and have completed the present invention.

B204 [wherein A is at least two elements selected from 3d, 4d, 4f or 5d transition metals or rare earth elements of the periodic table (excluding trivalent Fe and Co), and B is F
At least one of e, Co, Mn, or Cr is shown.

] That is, the magnetic color toner of the present invention is characterized by using the above-mentioned specific spinel ferrite, which is light in color and has excellent translucency, as a magnetic material, and by setting the particle size distribution of the spinel ferrite within the above-mentioned specific range. The advantage of this method is that it further enhances the light transmittance of the body particles and weakens its hiding power, making it possible to obtain clear color images without impairing the color tone of the colorant.

The present invention will be explained in more detail below.

The magnetic material used in the present invention is B20 as described above. (A and 8 are the same as above) It is spinel ferrite fine powder expressed by

In the formula, 3d transition metals include Sc, Ti, V, and C.
Transition metals with 4d such as r, Mn, Ni, and Cu include Y, Zr, Nb, Mo, Tc, Ru, and R.
h, Pd, Ag, etc. are 4f rare earth elements.
La, Ce, Pr, Nd, Pi, Sm, Eu,
Gd, Tb, Dy, Ho, Tm, Wb, L
Transition metals where u etc. are 5d include Hf, Ta, Id
, Re, O8, etc. are exemplified.

Unlike conventional ferrites, such spinel ferrite compounds are pale in color and have excellent translucency. Therefore, in magnetic color toners using such spinel ferrite compounds as magnetic materials, the color inherent to the magnetic material is hidden, and the coloration is improved. The unique color tone of the agent is efficiently expressed.

Further, in the present invention, it is necessary to set the particle size of the spinel ferrite compound in the range of 5 to 801A.

If the particle size of the ferrite compound is less than 5 mμ, the proportion of paramagnetism due to thermal fluctuation will increase, resulting in a decrease in magnetizing power, and if the particle size exceeds 80 mμ, the light transmittance will decrease, which is not desirable.

Further, the amount of spinel ferrite fine powder used in the present invention is preferably 25 to 120 parts by weight, preferably 40 to 100 parts by weight, based on 100 parts by weight of the binder resin. If the amount used is less than 25 parts by weight, the amount of magnetization as a toner will be small, and the effectiveness as a magnetic toner will decrease.
On the other hand, if it exceeds 120 parts by weight, the color inherent to the spinel ferrite fine powder will affect the color tone of the toner, which is not preferable.

The spinel ferrite fine powder used in the present invention is produced, for example, as follows.

At least two metal compounds of transition metals or rare earth elements of 3d, 4d, 4f or 5d of the periodic table (excluding trivalent Fe, Co), and Fe, Co, Mn or Cr
At least one metal salt selected from the following is mixed in an appropriate ratio and dissolved in water. The mixing ratio of the total amount of metal salts and water at this time is usually 1.0 to 4 moles relative to water IQ, preferably 1.0 to 3.0 moles relative to water IQ.

Then, an alkali such as caustic soda is added to this mixed solution to adjust its pH to preferably 11±1.

When p)i of the mixed solution is adjusted to the above value, a mixture of the metal hydroxide and water is obtained. This mixture is then subjected to a hydrothermal reaction. The heating temperature during hydrothermal reaction is usually 150
-300°C, preferably 180-250°C. If the heating temperature is less than 150°C, the reaction may not proceed sufficiently and an oxide may not be formed, and if it exceeds 300°C, the particle size becomes large, which is not desirable.

The hydrothermal reaction time is usually 1 to 5 hours, preferably 2 to 4 hours, although it depends on the scale. If the reaction time is less than 1 hour, the reaction may not proceed sufficiently to form an oxide, and if it exceeds 5 hours, the particle size will increase.

After the completion of the hydrothermal reaction, one reaction solution is cooled, water in the mixture is removed, and the mixture is dried to obtain spinel ferrite fine powder.

All known binder resins can be used to constitute the toner of the present invention. Specifically, homopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylic butyl acid copolymer, styrene-ethyl acrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene- Styrenic copolymers such as maleic acid copolymers and styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyvinyl butyl butyral, polyacrylic Acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin,
Examples include paraffin and wax, and these may be used alone or in combination of two or more.

Furthermore, the toner of the present invention can of course contain a colorant, and all pigments and dyes conventionally used as colorants for toners can be used. Specifically, Ultramarine Blue, Aniline Blue Luluco Oil Blue, and DuPont Oil Red.

Quinoline yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green.

Hanzai G, Rhodamine 6C Lake, Quinacridone, Benzine Yellow, Malachite Green, Hanza Yellow G, Rhodamine 6C Lake, Quinacridone, Benzidine Yellow, Malachite Green Hexalate, Rose Bengal, Monoazo Dyes and Pigments, Disazo Dyes and Pigments, Trisazo Dyes and Pigments and mixtures thereof.

Note that the toner of the present invention may optionally contain a charge control agent for controlling the charge of the toner, a fluidizing agent such as colloidal silica, a metal oxide such as titanium oxide, aluminum oxide, silicon carbide, etc. It may contain abrasives such as abrasives, lubricants such as fatty acid metal salts, and the like.

〔Effect of the invention〕

The magnetic color toner of the present invention has the following outstanding effects because spinel ferrite fine powder having a specific particle size distribution is used as the magnetic material.

(1) Since the magnetic material has excellent light transmittance and low coloring property, it is possible to provide clear color images.

(2) Since toner scattering can be prevented by using the binding force of a magnetic field, the toner scattering prevention means can be simplified, and the torque of the machine can be reduced.

(3) Generally, when non-magnetic toner is used in the -component development method, a replenishment roller is required to supply toner to the developing roller, but in the present invention, toner can be replenished by magnetic force, so the replenishment roller can be removed. I can do it.

(4) Magnetic reading of image information, which was conventionally possible only with black and white images, can now be applied to color images, expanding its uses.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these. In addition, parts shown below mean parts by weight.

[Production example of spinel ferrite fine powder (1)] 0.7 mol of magnesium sulfate heptahydrate, 0.3 mol of zinc sulfate heptahydrate, and hydrated ferric sulfate [Fe(SO4)3.nH2o] 1
．． 0 mol was dissolved in 10 mol of distilled water. A caustic soda aqueous solution was added to the obtained aqueous solution until the pH became 11±1 to gel the aqueous solution.

The obtained gelled product was loaded into a stainless steel autoclave, and a hydrothermal reaction was carried out over 3 hours while heating it to 220°C.

After the reaction was completed, the reaction solution was cooled and the contents were taken out from the autoclave to obtain a slurry-like suspension with a solid content of approximately 10% by weight.

The fine powder obtained by drying this at room temperature was pale red and transparent, and the average particle size determined by X-ray diffraction was 8 mμ.
The only mineral found was spinel. Moreover, the value of saturation magnetic moment was 31.4 emu/g.

In addition, the saturation magnetic moment is a value at an applied magnetic field of 5 KOe using a vibrating sample magnetometer (VSM-3 type) manufactured by Toei Kogyo.

[Production example of spinel ferrite fine powder (2)] 0.5 mol of manganese sulfate tetrahydrate, 0.5 mol of zinc sulfate heptahydrate, and hydrated ferric sulfate [Fe(S04), .nH2O] 1.0
mol and dissolved in distilled water IQ. In the resulting aqueous solution, p
) A caustic soda aqueous solution was added until I became 11±1 to gel the aqueous solution.

The obtained gelled product was placed in a stainless steel beaker and kept at 100° C. for 30 minutes in a water bath to carry out a hydrothermal reaction.

After the reaction was completed, the reaction solution was cooled and the contents were taken out from the stainless steel beaker to obtain a slurry-like suspension with a solid content of approximately 10% by weight.

The fine powder obtained by drying this at room temperature was dark black and transparent, and the average particle size determined by X-ray diffraction was 15 mμ, and only spinel was observed as the mineral. Moreover, the value of saturation magnetic moment was 48.4 parts mu/g.

Example 1 Styrene-n-butyl methacrylate copolymer 4
3.0 parts Quaternary ammonium salt (charge control agent) 2.0 parts Spinel ferrite fine powder of Production Example (1) 50
．． 0 part C, 1, Pigment Red 48:1
4.5 Part C, 1, Pigmen
t Red '57 0.
5 parts The mixture having the above composition was sufficiently stirred and mixed in a Henschel mixer, and then heated at 130°C to 140°C in a roll mill for 30 minutes.
The mixture was melted by heating for 1 minute, and then cooled to room temperature. This mixture was crushed and classified to obtain particles having a particle size of 5 to 10 thresholds.

A toner was obtained by adding and mixing 0.5 parts of colloidal silica to 100 parts of the particles.

When this toner was put into Mycopy-M10 (manufactured by Ricoh Co., Ltd.) and an image was produced, a clear red image was obtained. Further, the thin layer uniformity of the toner layer on the developing sleeve was good, the image uniformity was also excellent, and there was no toner scattering. Furthermore, even after a 10,000 copy test, high quality images with no scuffing were maintained.

Example 2 Styrene-〇-butyl methacrylate copolymer 4
4.5 parts 4I & ammonium salt (charge control agent) 2.0 parts Spinel ferrite fine powder of Production Example (2) 5
0.0 part C, 1, Pigment Blue 15
3.0 part C, 1, Pigmen
t Red 57 0.5
The mixture having the above composition was thoroughly stirred and mixed using a Henschel mixer, then melted by heating at 130°C to 140°C for 30 minutes using a roll mill, and then cooled to room temperature. This mixture was pulverized and classified into particles having a particle size of 5 to 10. particles were obtained.

A toner was obtained by adding and mixing 0.5 parts of colloidal silica to 100 parts of the particles.

When this toner was placed in Mycobee A10 (manufactured by Ricoh) and an image was produced, a clear blue image was obtained. Furthermore, the thin layer uniformity of the toner layer on the developing sleeve was good, the image uniformity was excellent, there was no toner scattering, and high image quality without background smudge was maintained even after a 10,000 copy test.

Example 3 Styrene-〇-butyl methacrylate copolymer 6
5.0 parts Quaternary ammonium salt (charge control agent) 2.0 parts Spinel ferrite fine powder of Production Example (1) 30
．． Part 0 C, 1, Pigment Yellow 17
3.0 parts The mixture having the above composition was sufficiently stirred and mixed using a Henschel mixer, then melted by heating at 130'C to 140C for 30 minutes using a roll mill, and then cooled to room temperature. This mixture was pulverized and classified into particles with a particle size of 5 to 5.
Particles of 1oIA were obtained.

A toner was obtained by adding and mixing 0.5 parts of colloidal silica to 100 parts of the particles.

When this toner was placed in a Myricopy MIO (manufactured by Ricoh Co., Ltd.) and one image was produced, a clear yellow image was obtained. Further, the thin layer uniformity of the toner layer on the developing sleeve was good, the image uniformity was also excellent, and there was no toner scattering. Furthermore, even after a 10,000 copy test, high image quality with no background smudges was maintained.

Claims (1)

[Claims] (1) At least a binder resin, a colorant, and an average particle size of 5 or more
A magnetic color toner characterized by containing the following spinel ferrite fine powder having a particle size of 80 mμ. AB_2O_4 [wherein A is at least two elements selected from 3d, 4d, 4f or 5d transition metals or rare earth elements of the periodic table (excluding trivalent Fe and Co), and B is Fe
, Co, Mn or Cr. ]