JPH03212655A - Electrostatographic developer - Google Patents

Abstract

PURPOSE:To obtain satisfactory recording density with a small amt. of a toner consumer by forming the toner with a binding resin, a colorant, an electric charge controlling agent and ultramarine. CONSTITUTION:A mixture of 100pts. wt. styrene-acrylic resin with 8 pts. wt. carbon black, 2 pts. wt. electric charge controlling agent and 7 pts. wt. ultramarine is heated, stirred, solidified by cooling and pulverized to form a toner having 12mum average particle size and 5-30 mum particle size distribution. The electric charge controlling agent is an electron donating dye such as nigrosine, an electron accepting dye such as alkoxyamine or an electron accepting org. complex. The ultramarine is produced by mixing 90pts. wt. kaolinite with 10pts. wt. silicic acid, 65pts. wt. Na2CO3 85pts. wt. S and 10pts. wt. CaCO3 and calcining the mixture in vacuum. Since the reddish tinge of the carbon black is vanished by the bluing effect of the ultramarine having high coloring power and intense light absorption at a long wavelength side, the blackness of the carbon black is visually enhanced and a high-quality image is obtd. with a small amt. of the toner consumed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrostatographic developer used in PPC copying machines and printing devices.

Conventional technology Conventionally, in a system using a two-component developer, an electrostatic photographic developer mixes toner at a certain ratio with iron powder or ferrite powder with a particle size of 50 to 150 μm as a carrier, and then triboelectrically charges the two by stirring. I am using it. The toner used here includes a coloring agent such as carbon black in a binder resin such as a styrene resin or an acrylic resin, and a charge control agent such as a nigrosine dye or a monoazo dye so that a desired charge is imparted to the toner by the frictional charging. The additive is added, the mixture is heated and melted, and the powder is further finely pulverized to adjust the particle size to an appropriate particle size as necessary.

On the other hand, in a system using a one-component developer, a toner in which iron powder or ferrite powder of 1 μm or less and a colorant such as carbon black and a charge control agent are dispersed in a binder resin is used as a developer. It was used by frictionally charging the sleeve, blade, etc.

To form a visible image using such toner, regardless of whether it is a one-component system or a two-component system, it is necessary to spray it onto an electrostatic latent image formed on a photoreceptor such as zinc oxide, an organic photoreceptor, or selenium. The toner is electrically attached and developed, and then this toner is transferred to recording paper and fixed to form a visible image.

Problems to be Solved by the Invention In such a conventional configuration, it is necessary to attach a certain amount or more of toner in order for the visible image formed on the recording paper to exhibit the desired recorded image density (hereinafter referred to as ID). be.

Therefore, in order to obtain sufficient ID, attempts are generally made to increase the amount of toner adhesion by setting the toner charge amount low, but with this method, the amount of toner consumption increases and There is a problem that the number of printed sheets decreases in relation to the amount of printing, and so-called background fog development occurs in which toner adheres to the white portion of the recording paper.

In addition, the charge control agent, carbon black, and other substances that control charging are not uniform among all toner particles, and the toner particles themselves have a particle size distribution of about 5 μm to 30 μm. There is a distribution of triboelectrification of toner, and toner particles with a specific amount of charge are selectively developed. Therefore, even if a predetermined ID can be obtained at the beginning of printing, there is a problem in that the amount of charge of the developer increases as the number of sheets printed increases, the amount of toner adhesion decreases, and the ID decreases.

Furthermore, in order to form a halftone visible image, a conventional toner using only carbon black as a colorant has a brown hue and does not give the impression of blackness. Therefore, conventional toners are not suitable for electrostatic recording of graphic images.

The present invention solves these problems, and provides a developer that consumes less toner, does not cause background fogging, has excellent halftone reproduction characteristics, and forms recorded images with a sufficiently high ID. The purpose is to

Means for Solving the Problem In order to solve this problem, the present invention adds ultramarine to at least a binder resin, a colorant, and a charge control agent,
By using heat-melted and dispersed toner as an electrostatic photographic developer, it is possible to reproduce recorded images with a sufficiently high ID.

The recording density by electrostatic photography is determined by the optical properties of carbon black, which is a colorant, that is, the light absorption wavelength characteristics. That is, the light absorption wavelength characteristic of carbon black has a strong wavelength dependence, and in particular, the absorption value on the long wavelength side decreases almost linearly compared to the short wavelength side. Therefore, the blackness of the recorded image is sufficient, and in particular, the halftone image becomes brown and does not give the impression of blackness. Therefore, by adding ultramarine, which has high coloring power and exhibits strong absorption on the long wavelength side, the bluing effect of ultramarine eliminates the reddish tinge of carbon black and visually improves the blackness.

Examples The binder resin of the toner used in the present invention is not particularly limited, but includes polystyrene and copolymers, polyester and copolymers, polyethylene and copolymers,
Epoxy resins, acrylate and methacrylate resins and copolymers.

Silicone resins, polypropylene and copolymers.

Wax (paraffin), fluororesin, polyamide resin, polyurethane resin, etc. can be used alone or in combination.

Further, as the coloring agent used in the present invention, conventionally known carbon black or the like is used.

Furthermore, as the charge control agent, as mentioned above, electron-donating dyes such as nigrosine, alkoxylated amines, quaternary ammonium salts, and alkylamides are used.

Molybdate chelate pigments, electron-accepting dyes such as metal complexes of monoazo dyes, electron-accepting organic complexes, chlorinated polyolefins, sulfonylamines of copper phthalocyanine, and the like are used.

Further, the ultramarine used in the present invention includes 90 parts by weight of kaolinite, 10 parts by weight of silicic acid, and 65 parts by weight of sodium carbonate.
parts by weight, 10 parts by weight of Bio 985 heavy 1 rotary coal,
It is synthesized by baking at 750° C. for 10 hours in a vacuum, cooling, thoroughly washing with water, and thoroughly drying.

The amount of ultramarine added is 4 to 12% by weight, especially 6
A range of 10% by weight is preferred. If the amount of ultramarine added is smaller than the above range, no effect of improving blackness can be obtained. On the other hand, if it is too large, the hue becomes bluish and the degree of blackness decreases.

The basic configuration of the present invention has been described above, and a specific embodiment of the present invention will be described in detail below.

Styrene-acrylic acid resin (Genkasei ZSR-10
08) 100 parts by weight, carbon black (Mitsubishi Kasei M
A-100) 8 parts by weight, 2 parts by weight of a charge control agent (Bontron S-34 manufactured by Orient Chemical Co., Ltd.), and 7 parts by weight of Ultramarine were mixed and stirred in a heated niegu, then cooled and solidified, and pulverized and classified to 5 to 30 μm. The average diameter with a particle size distribution of 1
A toner of 2 μm was obtained.

Erica powder (Aerosil R972 manufactured by Nippon Aerosil Industries Co., Ltd.) was added as an external additive to 100 parts by weight of the obtained toner.
0.3 parts by weight was mixed and stirred in a Henschel mixer for 25 minutes to perform surface treatment of the toner.

4 parts by weight of the obtained toner was transferred to a ferrite carrier (TDK
A two-component developer was obtained by adding 100 parts by weight of LC-002 (manufactured by Co., Ltd.) and mixing and stirring using a V-type blender.

Comparative Example In the above example, without adding ultramarine,
A two-component developer was obtained under the same conditions as in the example. Using the toner and developer obtained in Examples and Comparative Examples, a printing test was conducted using a laser beam printer equipped with a chargeable organic photoreceptor, and the number of printed sheets and ID (measured with a Macbeth thermometer), Changes in background fog (measured with a Hunter whiteness meter) and transfer amount were investigated.

The laser beam printer is composed of a photoreceptor, a sleeve containing a magnetic roller disposed opposite to the photoreceptor, and a packet in which developer and toner are mixed and charged by friction. Further, the fixing method used was a thermocompression bonding method consisting of a combination of a heating roller and a pressure roller.

The printing results are shown in Tables 1 to 3.

Table 2 Change in background fog (according to Hunter whiteness meter) Table 3 Change in transfer amount (■/sheet) As described above, the toner according to the present invention can provide sufficient recording density despite the small transfer amount. Ta.

Further, the recorded density of the toner of the example was compared with that of the toner of the comparative example, and a visual difference in blackness was felt based on the difference in the value measured with a Macbeth densitometer. This is because by adding phthalocyanine blue as described above, it was absorbed on the long wavelength side and the red color disappeared.

Effects of the Invention As is clear from the description of the embodiments above, according to the present invention, by using a toner consisting of at least a binder resin, a colorant, a charge control agent, and ultramarine, it is sufficient to reduce toner consumption. The effect is that a high recording density can be obtained.

Claims (1)

[Claims] An electrostatic photographic developer comprising at least a binder resin, a colorant, and a charge control agent, to which ultramarine is added.