JPS59187347A - Magnetic toner - Google Patents

Abstract

PURPOSE:To form a clear image having considerably improved quality or cleanability in environment at high temp. or low humidity by using a magnetic toner consisting of magnetic powder, a binder resin, a flowability providing agent, electrically conductive fine particles and a lubricant. CONSTITUTION:This magnetic toner consists of 20-120pts.wt. magnetic powder, 100pts.wt. binder resin, 0.1-2.0pts.wt. flowability providing agent, 0.01-5pts.wt. electrically conductive fine particles and 0.01-2.0pts.wt. lubricant. The toner may further contain 1-20pts.wt. coloring agent. The magnetic powder has a particle size distribution in which the diameter of cumulative 50vol% of the powder is 1.5-6.5mum, preferably 2.0-5.5mum, that of cumulative 25vol% is 1.0- 5.0mum, preferably 1.5-4.5mum, and that of cumulative 75vol% is 2.5-7.5mum, preferably 2.5-6.5mum.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner used in electrophotography, electrostatic printing, magnetic recording, and the like.

Electrophotography is described in US Pat. No. 2,297,691, British Patent No. 1,165,406 and British Patent No. 1145.
405, a number of methods are known, but generally utilize a photoconductive material to form an electrical latent image on a polyphotoreceptor by various means, and then The latent image is developed using toner, and the toner image is transferred to a transfer material such as paper depending on the need, and then fixed by heat, pressure, solvent vapor, etc. to obtain a copy.

The electronic printing method, as proposed in Japanese Patent Publication No. 42-14342 (West German Patent No. 1203808), is a method of guiding and fixing a charged powder toner onto a recording material using an electric field for printing. be.

The electrostatic recording method is a method in which charges are applied in the form of an image on a galvanic material layer, and charged toner powder is attached and fixed thereon. Similarly, the magnetic printing method is a method in which a magnetic latent image is created on a recording material. This is a method in which the image is formed, developed with toner powder containing a magnetic material, transferred to a transfer material, and fixed.

There are various developing methods for visualizing such electrical and magnetic latent images using toner, and they can be broadly classified into dry developing methods and wet developing methods. The former method is further divided into two methods: a method using a two-component developer using carrier particles, and a method using a single-component developer not using carrier particles.

Among the two-component developing methods, a magnetic brush method using an iron powder carrier, a cascade method using a bead carrier, and the like are widely put into practical use, depending on the type of carrier for conveying the toner.

On the other hand, various developing methods using one-component developers have been proposed, which improve the appearance of the toner, and among these, many excellent methods using magnetic toner have been put into practical use. Development methods using magnetic component developers include the MagneDry method using conductive toner, and the method using dielectric polarization of toner particles as described in Japanese Patent Application Laid-Open No. 52-94140 (West German Patent No. 2704561). , Japanese Patent Publication No. 53-3113
6 (U.S. Pat. No. 4,121,931), the method of charge transfer by toner disturbance, and the methods proposed in recent years by the present applicant, such as JP-A-54-42141 and JP-A-55-
A method of developing a latent image by flying toner particles as disclosed in Japanese Patent No. 18656 has been put into practical use.

Nowadays, electrophotography and the like are used for a variety of purposes, and there is a demand for a compact and inexpensive color copying machine that can produce images in desired colors as needed.

The above-mentioned magnetic component development method is suitable for small and inexpensive copying machines, but magnetic component toner has conventionally used magnetite or ferrite as its magnetic material. The color is black or dark brown, and although it is effective for obtaining black toner, it has been a major obstacle for obtaining so-called color toner.

In order to overcome this obstacle, it has been proposed to whiten or color the black magnetic material. However, in the above method, since the magnetic substance contained in the toner is a fine powder, whitening and coloring methods are difficult, and the process becomes complicated, resulting in an expensive product.

Another drawback was that the color of the magnetic material could not be erased unless a large amount of coloring agent was used.

On the other hand, a method of increasing the particle size of the magnetic material to reduce the coloring power of the magnetic material was considered, but since large magnetic materials tend to exist non-uniformly in the resin, the developability of magnetic toner, such as deterioration of image quality, and magnetic There were drawbacks such as image deterioration in durability due to background smearing due to particles that do not contain particles.

Previously, the present applicant has solved the above-mentioned drawbacks when magnetic powder having at least a certain particle size and a certain particle size distribution, a binder resin, and conductive fine particles are contained for the purpose of reducing charge-up of toner. Although it has been found that it is possible to obtain a magnetic color toner that overcomes the above problems, there is a possibility that it will not be sufficient to improve image quality or cleanability in a high-temperature environment or a low-humidity environment.

As a result of intensive studies to improve the above-mentioned properties, the present inventors have found that a magnetic toner consisting of at least magnetic powder and a binder resin contains a fluidity imparting agent, conductive fine particles, and a lubricant at the same time. , surface modification is performed by adjusting the fluidity, surface activity, and electrical resistance of the toner.
A magnetic color toner with the above properties further improved can be obtained. I discovered that.

That is, an object of the present invention is to provide a magnetic toner that has further improved properties as described above and can produce clear images.

A further object of the present invention is to provide a magnetic color toner that has a simple manufacturing process and is inexpensive.

A further object of the present invention is to provide a magnetic color toner that has even better developability, transferability, and fixability.

A further object of the present invention is to provide a magnetic color toner with excellent durability and stability against environmental changes.

The present invention is characterized in that a magnetic toner comprising magnetic powder, a binder resin, a fluidity imparting agent, conductive fine particles, and a lubricant is used, preferably a volume-based integration of 50% of the magnetic powder.
The diameter is 1.5 to 6.5μ (preferably 2.0 to 5.5μ)
μ), the 25% diameter is 1.0 to 5.0 μ (preferably 1.5 to 4.5 μ), and the 75% diameter is 2.5 to 7.5 μ (
It preferably has a particle size distribution of 2.5 to 6.5 microns.

Here, the volume-based integrated 50% diameter (25% diameter, 75% diameter)
means that the volume of the measured particles is added starting from the smallest particle size, and the cumulative amount is 50% of the total volume of the measured particles (
25%, 75%).

The magnetic powder used in the present invention has a volume-based integration of 50
% diameter is 1.5~6.5μ, 25% diameter is 1°0~5.5
μ, powder of ferromagnetic elements and alloys and compounds containing these elements with a particle size distribution of 2.5 to 7.5μ, e.g. iron, cobalt such as magnetite, γ-hemakite, ferrite, etc. There are conventionally known ferromagnetic materials, such as alloys and compounds of nickel, manganese, and other ferromagnetic alloys. In particular, magnetite and the like are suitable for blue or green magnetic toners, and γ-hemacite and the like are suitable for yellow or red magnetic toners.

The reason why the particle size range of the magnetic powder used in the present invention is shown above is that if the particle size of the magnetic powder is thicker, it will be easier to color with the colorant, but the dispersion of the magnetic powder in the toner particles will be smaller. Toner particles that do not contain magnetic powder tend to be non-uniform, and toner particles that do not contain magnetic powder are likely to be formed, resulting in deterioration in image quality, background smearing, etc., and this tendency is particularly strong in a low-humidity environment.

On the other hand, if the particle size of the magnetic powder is smaller than these ranges, coloring by the magnetic material will be strong, coloring by coloring agents other than the magnetic material will be difficult, and at the same time the fixing temperature will be high, resulting in poor fixing performance.

The above magnetic powder can be produced by any method such as pulverization, particle growth during wet sedimentation, sintering of magnetic material, or particle growth using 7 lux. The sintering method or the 7 lux method is preferable because it allows the diameter to be narrower. In particular, magnetic powder produced by the sintering method or flux method accounts for 6% of the total amount of magnetic powder.
The content is preferably 0% by weight or more (preferably 80% by weight or more). Furthermore, if necessary, the magnetic powder may be subjected to surface treatment such as titanium coupling treatment or coloring treatment such as dyeing.

The magnetic toner in the present invention has at least a magnetic binder resin, a fluidity imparting agent, conductive fine particles, and a lubricant, and the composition ratio thereof is 20 to 120 parts by weight of magnetic powder to 100 parts by weight of the binder resin. (preferably 40 to 80 parts by weight), fluidity imparting agent 0.1 to 2.0 parts by weight (preferably 0.2 to 1.0 parts by weight), conductive fine particles 0.01 to 2.0 parts by weight
5 parts by weight (more preferably 0.05 to 2 parts by weight), lubricant 0.01 to 2.0 parts by weight (more preferably 0.05 to 2 parts by weight)
1.0 parts by weight), 1 to 20 parts by weight of colorant as necessary (
(more preferably 5 to 15 parts by weight). If the amount of conductive fine particles is less than this, the image quality will not be sufficiently improved, especially at low humidity, and on the other hand, if the amount is too large, the image density will decrease, especially at high humidity.

The conductive fine particles used in the present invention have an approximate number average particle diameter of about 0.01 to 5μ as determined by electron microscopy.
Fine particles having a specific surface area of about 1.5 m 2 /g or more and an electrical resistance of about 10 10 Ωα or less as determined by the nitrogen adsorption method can be used. For example, carbon black, graphite,
Iron oxide, tin oxide, zinc oxide, metal powder, etc. can be used, but
Metal oxides, particularly tin oxide and zinc oxide, are preferred. Here, the electrical resistance is 1oo9/d when the cell is filled with conductive particles.
It is measured by applying a voltage of about 1 oV/ciz or less under a pressure of .

As the binder resin, homopolymers of styrene and its substituted products, such as polystyrene, poly-P-chlorostyrene, polyvinyltoluene, styrene-P-chlorostyrene copolymer, styrene-vinyltoluene copolymer, and copolymers thereof; ;Styrene-methyl acrylate copolymer, styrene-
Copolymers of styrene and acrylic esters such as acrylic acid-n-butyl copolymers; styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-methacrylic acid-n-butyl copolymers Copolymers of styrene and methacrylic esters; multi-component copolymers of styrene and acrylic esters and methacrylic esters; other styrene-acrytetranitrile copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene Styrenic copolymers of styrene and other vinyl monomers, such as copolymers, styrene-vinyl methyl ketone copolymers, styrene-acrylonitrile-indene copolymers, and styrene-maleic acid ester copolymers;
Polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate/Iz, polyester, polyamide, epoxy resin, polyvinyl buteller ash, polyacrylic acid,
Known binding substances such as phenol resin, aliphatic or alicyclic hydrocarbon resin, petroleum resin, and chlorinated paraffin can be used alone or in combination.

Furthermore, low molecular weight polyethylene is used as a binder resin for toners used in pressure fixing systems.

Low molecular weight polypropylene, ethylene vinyl acetate copolymer, ethylene vinyl acetate copolymer, ethylene acrylic acid ester copolymer, higher fatty acid, polyamide resin, polyester resin, etc. are used alone.As a fluidity imparting agent, colloidal silica etc. .

As the lubricant, known substances such as higher fatty acids and their metal salts, amines, esters, amides, and fluorine compounds such as polyvinylidene fluoride and polytetrafluoroethylene can be used.

Any inorganic pigment or organic dye or pigment can be used as the coloring agent if necessary, but water-soluble dyes are not preferred because they are susceptible to wetting even after the image is fixed, and black pigments such as carbon black are not preferred. Although these are not preferable in obtaining color toners, they can be used for the purpose of improving the properties of the toner as long as they do not significantly deteriorate the properties of the toner of the present invention.

Pigments that can be used in the present invention include, for example, benzidine yellow, Hansa yellow, phthalocyanine blue, phthalocyanine green, navy blue, ultramarine blue, cobalt plastic, quinacridone, toluidine toner, permanent yellow, Palcan first yellow, permanent orange, Palcan first orange. , Indance Brilliant Orange, Permanent Red.

Palquan Fast Pink, Brilliant Carmine, Indan Stremburu, Naphthol Green, etc. are powerful. Also, as a dye, C-12700, 0-8690. C
1873 pot.

C engineering 26020, C engineering 12150. C engineering 12715.
C engineering 60725. C F4350゜C Eng 61565. C
Month 0345. C-work 48000, C-work 11080. C
Engineering 11100°C Engineering 62015. C engineering 64500. C-62500 and the like are available, but it is preferable to use one that has good compatibility with the binder used.

Further, the toner of the present invention may further contain, if necessary, a fixing aid such as low molecular weight polyethylene, and an abrasive such as cerium oxide.

For the production of magnetic toner, hot rolls, kneaders,
A method of kneading the constituent materials well using a thermal kneader such as an extruder, followed by mechanical pulverization and classification; Alternatively, a method of dispersing materials such as magnetic powder in a binder resin solution and then spray drying. Alternatively, various methods can be applied, such as a polymerized toner manufacturing method in which a magnetic toner is obtained by mixing a specific material with a coulomer that constitutes a binder resin and then polymerizing this emulsified suspension. .

In addition, in the present invention, the particle size distribution of the magnetic powder is
Measurements were made under appropriate conditions using a counter model TA-nu and an aperture tube with a diameter of 50 μm.

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto in any way.

Note that all parts in the following formulations are parts by weight.

[Example 1] Styrene-butylene acrylate/I/(70:3 copolymer 100 parts Magnetic powder (magnetite 50% diameter 5.16μ
, 60 parts 25% diameter 4.38μ, 75% diameter 6.05
μ) 7-tetocyanine blue 10 parts The above mixture is kneaded at 150° C. with a roll mill, and after cooling, coarsely ground with a speed mill. After that, it is finely pulverized with a jet mill, and a powder of 5 to 20μ is obtained with an air classifier, and this is supplemented with 0.5 parts of colloidal silica as a fluidity imparting agent, 0.5 parts of tin oxide as conductive particles, and lubricant. A blue magnetic toner was obtained by adding 0.05 part of zinc stearate as an agent.

A commercially available plain paper copier (product name, PC-
20 (manufactured by Canon)), a very clear and high-density blue image was obtained. Further, when 3,000 copies were made continuously at low temperature and low humidity (15° C., 10% RH), clear images with high density were obtained, and there was no change in color tone.

[Comparative Example 1] Example 1 except that zinc stearate as a lubricant was not used.
When we obtained magnetic toner in the same manner as above and performed continuous copying, very high density and clear images were obtained after 2,000 copies, but after 2,500 copies, there was severe filming on the drum surface, especially in high-temperature environments. At the bottom, cleaning performance decreased.

[Comparative Example 2] A magnetic toner was obtained in the same manner as in Example 1 except that the conductive fine particles of tin oxide were not used, and continuous copying was performed.
The image quality deteriorated due to continuous copying of about 0 sheets.

[Example 2] Styrene-butyl acrylate (70:30) copolymer 100 parts Magnetic powder (magnetite 50% diameter 3.68μ
60 parts 25% diameter 2.81μ, 75% diameter 3.86μ
) Low molecular weight polyethylene 4 parts Phthalocyanine blue 10 parts Using the above materials, 0.5 parts of colloidal silica as a fluidity imparting agent,
Example 1 was prepared by adding 0.5 parts of zinc oxide as conductive particles and 0.2 parts of polyvinylidene fluoride as a lubricant.
When we obtained magnetism in the same manner as above, we obtained an even clearer, higher-density blue image. When 3000 further copies were made, clear images with high density were obtained, and there was no change in color tone.

[Example 3] Styrene-butyl methacrylate (75:25) copolymer 100 parts Magnetic powder (magnetite 50% diameter 4.68μ,
60 parts 25% diameter 3.82μ, 75% diameter 5.21μ
) 3.5-Di-tert-butylsalicylic acid chromium complex salt 2 parts Low molecular weight polyethylene 5 parts Phthalocyanine blue 10 parts Using the above materials, 0.5 parts of colloidal silica as a fluidity imparting agent, 0.5 parts as conductive fine particles A blue toner was obtained in the same manner as in Example 1 by adding 0.02 parts of zinc oxide and 0.02 parts of zinc stearate as a lubricant. As a result, a clear blue image with high density was obtained. Furthermore, a durability test of 10,000 sheets was conducted using this magnetic toner, and clear images with extremely high density were obtained, including when toner was replenished. The same result was observed under a high temperature environment (30° C., 90% RH) and under a low temperature and low humidity environment (15° C., 10% RH).

[Example 4] 100 parts of styrene-butyl methacrylate (75:25) copolymer magnetic powder (γ-F020550% diameter 4.86μ,
70 parts 25% diameter 4.10μ, 75% diameter 5.12
μ) 3.5-di-tert-butylsalicylic acid silom complex salt 2 parts low molecular weight polyethylene
5 parts Brilliant Carmine 6B 8 parts Using the above materials, 0.8 parts of colloidal silica as a fluidity imparting agent, 1.0 parts of tin oxide as conductive particles,
A red toner was obtained in the same manner as in Example 1 with the addition of 0.1 part of polyvinylidene fluoride as a lubricant, and when the image was printed using a commercially available copying machine (trade name: NP2O0J Canon m), the image was even clearer. A high-density red image was obtained.

Furthermore, a durability test of 10,000 sheets was conducted using this magnetic toner, and clear images with high density were obtained, including when toner was replenished. Also under high temperature environment (30℃, 90%RE
) and under a low temperature, low humidity environment (15° C., 10% RB).

Applicant: Canon Co., Ltd.

Claims (1)

[Scope of Claims] (1) A magnetic toner comprising magnetic powder, a binder resin, a fluidity imparting agent, conductive fine particles, and a lubricant. (2) The magnetic powder has a volume-based integrated 50% diameter of 1.5 to 6.
5μ, 25% diameter is 1.0 to 5.5μ, 75% diameter is 2.5
Claim 1 having a particle size distribution of ~7.5μ
Magnetic toner as described in section. (5) For 100 parts by weight of the binder resin, the fluidity imparting agent is 0.1 to 2.0 parts by weight, the conductive fine particles are 0.01 to 5 parts by weight,
The magnetic toner according to claim 1, wherein the magnetic toner contains 0 parts by weight and 0.01 to 2.0 parts by weight of the lubricant.