JPH0358056A - Electrostatographic developer - Google Patents

Abstract

PURPOSE:To enhance optical recording density by using a toner containing a blue pigment. CONSTITUTION:A toner containing a binder resin, such as a styrene-acrylic copolymer, a colorant, such as carbon black, an electric charge controller, and as the blue pigment (A), Berlin blue, such as KFeIIFeIII (CN)6, thus permit ting absorption in the longer wavelength region to be enhanced, reddish color to be eliminated, and blackness to be elevated.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a toner for use in an electrostatographic developer.

Conventional technology Conventionally, in a system using a two-part developer as an electrostatic photographic developer, a particle size of 6 to 15 mm is used as a carrier.
Toner is mixed with 0 μm iron powder 1 or 7 ELITE powder at a constant ratio, and both are frictionally charged by stirring.

The toner used here includes a coloring agent such as carbon black in a binder resin such as styrene resin or acrylic resin, and a nigrosine dye, monoazo dye, etc. so that the toner is given the desired charge during the frictional charging. A charge control agent is added, heated, melted and dispersed, and pulverized to a suitable particle size as required for use.

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

To form a visible image using such toner, 1 minute,
2 Regardless of the amount of time, toner is attached to an electrostatic latent image formed on a photoreceptor such as zinc oxide, organic zinc, organic photoreceptor, selenium, etc., and developed, and then this toner is recorded. Transfer it to paper and fix it to create a tangible image.

Problem to be Solved by the Invention The visible image formed on recording paper has a desired recording density (hereinafter referred to as I).
(referred to as D), it is necessary to attach a certain amount or more of toner.

Therefore, sufficient image density (image density below ID
Generally, attempts are made to increase the amount of toner adhesion by setting the toner charge amount to a low value in order to obtain There is a problem in that the so-called background fogging phenomenon occurs in which the toner adheres to the white background portion of the recording paper.

1. Also, due to the fact that the substances that control charging, such as charge control agents and carbon black, are not uniform among all toner particles, and the toner particles themselves have a particle size distribution of about 6 to 30 μm. , there is a distribution in the triboelectric charging of the toner, and toner particles with a certain amount of charge are selectively developed. For this reason, even if a predetermined ID is obtained at the beginning of printing, the amount of charge on 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, the 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.

In view of the above-mentioned problems, an object of the present invention is to form a recorded image with a sufficiently high ID by using a 1.ner in which navy blue is added to a binder resin, a colorant, and a charge control agent as a developer. shall be.

Means for Solving the Problems In the present invention, a toner in which navy blue is added to at least a binder resin, a colorant, and a charge control agent, and heated and melted and dispersed is used as an electrostatic photographic developer.

Function Recording density by electrostatic photography is caused by the optical properties, ie, absorption properties, of carbon black, which is a colorant.

That is, the absorption characteristics of carbon black are highly dependent on wavelength, and in particular, the absorption value on the long wavelength side decreases almost linearly compared to measurements at short wavelengths. Therefore, the blackness of the recorded image is insufficient, and especially in half 1/1, the image does not appear brown or υ black. The present invention uses deep blue with high coloring power that exhibits strong absorption on the long wavelength side. By adding this, the blackness will be improved.

Example Examples of the present invention will be described below.

Binder resins for the toner used in the present invention are not particularly limited, but include polystyrene and copolymers, polyester and copolymers, polyethylene and copolymers, epoxy resins, acrylate and methacrylate resins, and copolymers. Polyurethane resins, silicone resins, polypropylene and copolymers, wax (paraffin), fluororesins, polyamide resins, polyurethane resins, etc. can be used alone or in combination.

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

Further, as charge control agents, as mentioned above, electron-donating dyes such as nigrosine, alkoxylated amines, quaternary ammonium salts, alkylamides, molyponic acid chelate pigments, and electron-accepting dyes such as metal complex salts of monoazo dyes are used. ，
Electron-accepting organic complexes, chlorinated polyolefins, sulfonylamines of copper phthalocyanine, etc. are used.

Further, the navy blue used in the present invention includes potassium hexacyanoferrate, iron ammonium hexacyanoferrate, and the like.

The amount of navy blue added is 0.5 to 7 wt%, especially 2 to 4 wt%.
A good range is t%. If the amount of navy blue added is smaller than the above range, the effect of improving blackness will not be achieved; on the other hand, if it is too large, the hue will become bluish and the blackness will decrease.

The basic structure of the present invention has been described above, and the present invention will be specifically explained in detail below.

Example 1 Styrene-acrylic acid resin (ZSR-1o manufactured by Fujikura Chemical Co., Ltd.)
os: Noo weight part, carbon black (manufactured by Mitsubishi Kaoru H)
8 parts by weight of A-100), 2 parts by weight of a charge control agent (Borotron S-32 manufactured by Orient Chemical Co., Ltd.), and 3 parts by weight of Prussian blue (ferric hexacyanoferric acid potassium manufactured by Hoechst Javan) were mixed and stirred in an accelerator. Thereafter, the toner was cooled and solidified, and subjected to pulverization and classification to obtain a toner having an average particle size of 12 μm and a particle size distribution of 6 to 30 μm. For 100 parts by weight of the obtained 1-ner,
Silica powder (Aerosil R-972 manufactured by Nippon Aerosil Industries Co., Ltd.) as an external additive o. The toner was surface-treated by mixing and stirring for 6 minutes using a 3-way Henschel mixer.

Four parts by weight of the obtained toner was transferred to a ferrite carrier (TDK
In addition to 100 parts by weight of IC-002 manufactured by
A certain amount of developer was obtained by mixing and stirring using a /under.

Comparative Example 1 Based on Example 1, carbon black (Mitsubishi Kabo MA
-100) 10 parts by weight, 3 parts by weight of the charge control agent (Orien 1, S-32 manufactured by Kagaku Co., Ltd.), and the amount of Prussian blue not added were changed to obtain a 2-pack developer in the same manner as in Example 1.

As described above, using the toner and developer obtained in Example 1 and Comparative Example 1, a printing test was conducted using an LBP equipped with an O-charging OPC sensitive/photosensitive body, and the number of printed sheets and ID (Macbeth densitometer) were tested. ), Jikabu 1) (measured with a Hunter whiteness meter),
Changes in transcript levels were investigated.

The LBP consists of a photoconductor, a sleeve button containing a magnetic roller disposed opposite to the photoconductor, and a packet in which developer and toner are mixed and triboelectrically charged. The fixing method is a thermocompression bonding method using a combination of a heating roller and a pressure roller.

The printing results are shown in Tables 1-3.

As described above, with the toner according to the present invention, sufficient recording density was obtained despite the small amount of transfer.

Further, the recording density of the toner of Example 1 was compared with that of the toner of Comparative Example 1, and the difference in blackness was perceived by human eyes to be greater than the difference in the value measured with a Macbeth densitometer. This is because, as mentioned above, the addition of navy blue absorbs light on the longer wavelength side and eliminates the reddish tint.

Advantages of the Invention By using a toner consisting of at least a binder resin, a colorant, a charge control agent, and navy blue, a sufficient recording density can be obtained even with a small amount of toner consumption, and the effect is significant.

Claims (1)

[Claims] An electrostatic photographic developer characterized by using a toner comprising at least a binder resin, a colorant, a charge control agent, and a blue pigment.