JPS6026349A - Magnetic color toner - Google Patents

Abstract

PURPOSE:To fully cover the tone of a magnetic powder, enrich a toner hue, improve fixability, elevate image density, and reduce fog by using a magnetic powder having a specified surface area. CONSTITUTION:A magnetic color toner contains a magnetic powder having a BET specific suface area of 0.3-6m<2>/g measured by N2 adsorption method in an amt. of 20-120pts.wt. per 100pts.wt. of a binder resin, and 5-60 titanium white. The covering action of the titanium white is made easy by using a magnetic powder having such a specific surface area and the powder is made easily dispersed. Since the toner contains no magnetic powder readily deteriorating image quality and causing background stains and it can attain superior fixability. It may use any inorg. and org. pigment as a colorant, and as a magnetic powder, magnetite is suitable for blue and green types, and hematite is suitable for yellow and red types. As a result, a high-density sharp image can be obtained and it is not changed in tone by making a large number of copies, and superior in durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner for developing a latent image in electrophotography, electronic printing method 1, electrostatic recording method, magnetic recording method, etc., and particularly relates to a magnetic color toner.

Electrophotography uses the properties of photoconductors such as cadmium sulfide, polyvinylcarbazole, selenium, and zinc oxide to form electrostatic latent images. For example, a photoconductor layer is uniformly charged, This is a method in which an electrostatic latent image is formed by imagewise exposure, and then developed with toner powder charged with a polarity opposite to that of the electrostatic latent image, and further transferred to a transfer sheet and fixed as necessary. be.

The electronic printing method uses an electric field to guide and fix a charged powder toner onto a recording material for printing.

Electrostatic recording is a method in which charges are applied to a dielectric layer in the form of an image, and charged toner powder is attached to and fixed on the dielectric layer.Magnetic printing, similarly, forms a magnetic latent image on a recording material. This is then 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 magnet and a troll to form a magnetic brush, and the magnetic brush retains the electrostatic charge of the insulating material in the photoconductor such as cadmium sulfide. When the toner comes into contact with the body, the charge on the holder and the electrostatic charge or frictionally charged 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. This is advantageous in terms of low cost or miniaturization.

On the other hand, recently there has been a demand for a compact and inexpensive multi-color copying machine that can be used for a wide variety of purposes and that can produce images in different colors as needed.

The above-mentioned magnetic component development method is suitable for small and inexpensive copying machines; The color of the magnetic material is black or dark brown, which is effective for obtaining a black toner, but it has been a major obstacle to obtaining a so-called colored toner.

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 coloring pigment (1), but if the amount of magnetic material is reduced too much, developability will deteriorate. However, when the content of colored pigments was increased too much, problems such as deterioration of developability or deterioration of fixing performance occurred.

The present inventors conducted intensive studies to overcome this drawback, and as a result, they overcame the above drawback by using a magnetic material with a BET specific surface area due to a certain nitrogen adsorption and then incorporating titanium white. It has been found that magnetic color toner can be obtained.

That is, 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.

Furthermore, it is an object of the present invention that the obtained image has high density;
The purpose is to provide a magnetic color toner that is clear and has less fogging.

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

The magnetic color toner of the present invention is characterized in that the magnetic color toner containing at least magnetic powder, binder resin, and titanium white has a BET specific surface area of 0.3 to 6 m''/gz due to nitrogen adsorption of the magnetic powder. Preferably 0.5~
Contains magnetic powder with a diameter of 4m''/17mm.

The magnetic force 2-toner in the present invention contains at least a binder resin, a magnetic material, and titanium white, and the preferred composition ratio is 20 parts by weight of the magnetic material to 100 parts by weight of the binder resin.
~120 parts by weight (preferably 40 to 80 parts by weight), 5 to 60 parts by weight of titanium white (preferably 10 to 40 parts by weight),
1 to 20 parts by weight (preferably 5 to 1 part by weight) of a coloring agent if necessary.
5 parts by weight).

The magnetic powder used in the present invention is BE due to nitrogen adsorption.
Powders of ferromagnetic elements with a T specific surface area of 0.3 to 6 m''/9 and alloys and compounds containing them, such as iron, cobalt, nickel, and manganese such as magnetite, γ-hematite, and ferrite. There are alloys and compounds such as ferromagnetic alloys, and other ferromagnetic alloys that are conventionally known as magnetic materials.
γ-Hematite is suitable for yellow or red magnetic toner.

The specific surface area of the magnetic powder used in the present invention is shown above because if the specific surface area of the magnetic powder is as small as 0.3 m2/g, it will be easier to hide the magnetic material with titanium white. The dispersion of the magnetic powder in the toner particles tends to be non-uniform, and toner particles that do not contain a magnetic substance are also likely to form, resulting in deterioration of image quality and background smearing, which is especially strong under low Mid conditions.

On the other hand, if the specific surface area of the magnetic material is larger than 6 m" and 7 g, the coloring caused by the magnetic material will be difficult to hide with strong titanium white, and at the same time, the fixing temperature will be high and the fixing performance will deteriorate.

In addition, the above magnetic material can be manufactured by any of the following methods: pulverization, particle growth during wet sedimentation, sintering of the magnetic material, or particle growth using fusix, but it is possible to narrow the particle size distribution of the magnetic material. The sintering method or the fusics method is preferable because it can be used. Furthermore, the magnetic material may be surface-treated if necessary.

Furthermore, the manufacturing method most preferably used in the present invention is a sintering method, and specifically, α of about 0.3 to 1.0 μ
Fe2O3 is heated to 1000-1100℃ and sintered,
It is then mechanically crushed. If necessary, wet classification is performed through a 400 to 200 mesh filter. Furthermore, the obtained powder was heated to 250 to 500°C, and hydrogen and ProA? Ring element with etc. Thereafter, it is crushed to obtain magnetic powder used in the present invention.

The magnetic powder used in the present invention has a BET specific surface area of 0.3 to 6 m''/fi due to nitrogen adsorption.The volume-based cumulative diameter of 50 mm is 1.0 to 6.5 μm/fi.
The 5% diameter is 0.5 to 5.5μ, and the 75% diameter is 2.0 to 7.
It is desirable to have a particle size distribution of 5μ. In this case, the particle size distribution of the magnetic powder is determined by Coulter Counter Model TA-
The i value is measured under appropriate conditions using a type 1, 50μ diameter az4'-char tube.

As the titanium white used in the present invention, titanium white having a BET specific surface area of 1.0 to 10.0 m"/J9 due to nitrogen adsorption can be suitably used, but the specific surface area is 1.0 m"
If it is smaller than /9, the hiding power against magnetic powder will be reduced.Also, 10. This is because if it is larger than Om''/fi, the transparency increases and the hiding power decreases, and at the same time, the topography fixing point becomes high, which is not preferable.

Furthermore, the titanium white may be surface-treated with an inorganic compound such as alumina, silica tin oxide, a titanium powder horning agent, a silane coupling agent, or other organic treatment agent, if necessary.

Further, the binder resin used in the present invention includes polystyrene, polyp-chlorostyrene, ? Homopolymers of styrene and its substituted products, such as lipinyltoluene, styrene-p-chlorostyrene copolymer, styrene vinyltoluene copolymer, and copolymers thereof, styrene-methyl acrylate copolymer, styrene-acrylic Copolymers of styrene and acrylic esters such as acid-n-butyl copolymers, styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-n-butyl methacrylate copolymers, etc. Copolymers of styrene and methacrylic esters, multi-component copolymers of styrene and acrylic esters and methacrylic esters, other styrene-acrylonitrile copolymers, styrene-vinyl methyl ether copolymers, styrene-butadiene copolymers , styrene-based copolymers of styrene and other vinyl threads, such as styrene-vinyl methyl ketone copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic ester copolymers, polymethyl methacrylate, polybutyl methacrylate polyvinyl acetate, polyester,
Known binding materials such as polymamide, epoxy resin polyvinyl butyral, polyacrylic acid, phenol resin, aliphatic or ring hydrocarbon resin, petroleum resin, and chlorinated/4' rough-in can be used alone or in combination.

Furthermore, as binder resins for toners used in pressure fixing systems, low molecular weight polyethylene, low molecular weight polypropylene, ethylene vinyl acetate copolymers, ethylene vinyl acetate copolymers, ethylene acrylate copolymers, higher fatty acids, and polyamides are used. Resins such as polyester resins can be used alone or in combination.

Inorganic pigments and organic dyes and pigments can be optionally used as the colorant used in the present invention if necessary, but water-soluble dyes are not preferred because they are susceptible to wetting even after the image is fixed, and they are not suitable for coloring. Although black pigments such as black pigments are not preferable for 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.

Examples of pigments used in the present invention include benzidine yellow, Handy yellow, 7-thalocyanine blue, phthalocyanine green, navy blue, ultramarine blue, cobalt blue, quinacridone, toluidine tona N/#-Manent yellow, Palcan first yellow, and Noyama. Permanent Orange, Palkan First Orange, Indanthrene Brilliant Orange, Permanent Red, Palkan 7
These include earth pink, brilliant cursine, indane lentil, and naphthol green.

In addition, as a dye, C112700XC118690
゜C118736A, Cl26020, CI 1215
0. C112715CI60725, Cl74350
, Cl61565, C110345, Cl48000,
C111080, ellloo.

C162015, Cl64500, Cl62500, etc. are preferred, but those having good compatibility with the used Pineta 9- are preferred.

The toner of the present invention may further contain additives as required, such as lubricants such as polyvinylidene fluoride and polytetrafluoroethylene zinc stearate, or fixing aids such as Examples include low molecular weight polyethylene, a fluidity imparting agent 1, an anti-caking agent such as colloidal silica, and an abrasive such as cerium oxide.

In manufacturing this magnetic toner, heat rolls and kneaders are used.
After kneading the constituent materials well with a heat kneader such as an extruder, mechanically crushing and classifying them, or after dispersing materials such as magnetic powder in a binder resin solution,
A method for producing a magnetic toner by spray drying, or a polymerized toner production method for obtaining a magnetic toner by mixing a predetermined material with a monomer to constitute a binder resin and then polymerizing the emulsified suspension. Each method can be applied.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

Example 1 Styrene-methyl acrylate (70:30) copolymer
100 parts magnetic powder (magnetite specific surface area 1.0-1.4
mv1) 60 parts 7 talocyanine blue 1 part nigrosine 1 part titanium white (particle size 0.3 to 0.5 μ) 20 parts The above mixture was kneaded at 150°C in a roll mill, and after cooling, coarsely ground in a speed mill. do. Then finely pulverized with a jet mill,
A powder of 25 to 20 μm was obtained using an air classifier, and 0.5 part of colloidal silica was added thereto to obtain a blue magnetic toner.

This magnetic force 2-toner is applied to a commercially available copying machine (product name: PC20).
When imaged using a Canon camera, a very clear and high-density blue image was obtained. When 3000 further copies were made, clear images with high density were obtained and there was no change in color tone.

Comparative Example 1 A blue magnetic toner was obtained and imaged in the same manner as in Example 1 except that magnetic powder with a specific surface area of 7 to 9 m''/fi was used, but only a slightly blackish blue image was obtained. Further, when image printing was performed at high temperature and high humidity, the image density decreased.

Comparative Example 2 A blue toner was obtained in the same manner as in Example 1 except that magnetic powder having a specific surface area of 0.15 to 0.2 m''/9 was used,
When I tried to extract the image, I could only obtain an image with a lot of blurring. Furthermore, when continuous copying was performed, the image quality deteriorated after about 500 copies.

Comparative Example 3.4 When the image was displayed in the same manner as in Example 1 except that titanium white with a particle size of 0.05 to 0.1 μm and a particle size of 0.9 to 1.2 μm was used, the image looked a little dark. Only blue images were obtained.

Example 2 Styrene-butyl methacrylate (75:25) copolymer 100 parts Magnetic powder (γ-Fe20.5, specific surface area 2.0
~2.4m2/9) 70 parts low molecular weight polyethylene 5
A red toner was obtained in the same manner as in Example 1 using 1 part nigrosine, 1 part brilliant cursine 6B, 8 parts titanium white (particle size 0.3 to 0.5μ), and when an image was printed, it was very clear. A high density red image was obtained. The same result was observed even after 3000 sheets were used.

Example 3 Styrene-butyl methacrylate (75:25) copolymer 100 parts - Magnetic powder (magnetite, specific surface area 0.7~
1.0m2/,! 9) 50 parts 3-5-di-tert-butylsalicylic acid chromium salt 2
Low molecular weight? Liethylene 5 parts phthalocyanine! A blue toner was obtained in the same manner as in Example 1 using 10 parts of roux and 30 parts of titanium white (particle size 0.5 to 0.8μ), and image printing was performed using a commercially available copying machine (trade name: NP2O0J% manufactured by Canon). When this was done, a clear blue image with high density was obtained. Furthermore, when a durability test of 10,000 sheets was conducted using this magnetic toner, clear images were obtained, including when toner was replenished.

Claims (1)

[Claims] l In a magnetic color toner containing at least magnetic powder, binder resin, and titanium white, the BET ratio area due to nitrogen adsorption of the magnetic powder is 0.3 to 6 m''/9. Magnetic color toner characterized by
The magnetic color toner according to claim 1, characterized in that the magnetic color toner contains 0 mmt part. 3 Add titanium white to 5 to 6 parts of the binder resin xoo3I.
Claim 1 characterized in that it contains 0 parts by weight.
Magnetic color toner as described in section.