JPS5945454A - Electrophotographic developer - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic developer having superior electric characteristics, by treating carbon black (CB hereinafter) to be used for the developer with an alkaline soln. of humic acid or the like to disperse CB uniformly into the particles of the developer. CONSTITUTION:80g CB is added into an alkaline soln. obtd. by adding about 2g humic acid into 1 liter aq. soln. of pH 9. The liquid suspension thus obtained is vibrated with a vibrator for about 1hr to impregnate said CB with said soln. Then, CB is filtered and dried. A necessary amt. of mold releasing agent is added to the treated CB and a resin binder, kneaded, pulverized, and classified to obtain a powdery developer having about 12mum average particle diameter. As the humic acid, nitrohumic acid, its salt, regenerated humic acid, etc. can be used. A developer obtained by mixing said developer with a iron carrier by 4% of the carrier is charged to about 20.5muc/g, and a fog-free sharp image is obtained by using this developer.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an electrophotographic developer π used for developing an electrostatic latent image in an image forming apparatus employing electrophotography. .

[Technical background of the invention and its problems]

Conventionally, the components of a commonly known electrophotographic developer (hereinafter sometimes simply referred to as a developer) include carbon black, a resin binder, and a molding agent as needed in a two-component developer. , dyes, etc. Also, -component system
(The agent is a resin binder, magnetic powder, etc., and contains conductive carbon black to adjust the degree of blackness and resistance value.)

In this way, 1: The developer used for developing the child photograph (
Carbon black is essential, whether it is a one-component system or a non-component system. The carbon black has functions such as blackness, resistance value, and charge kick adjustment.
In order to fully exhibit this function, K is required to have a high dispersion in the developer.

By the way, the production of the developer is usually carried out as follows7'. That is, a resin binder, carpump knock, etc., which is a raw material, is premixed, and the resulting 7L mixture is heated with a three-roller or a kneader, and then mixed. Next, the mixed material is pulverized to a particle size of about 5 μm to 25 μm and classified to obtain an electrophotographic developer.

Therefore, in order to achieve high dispersion of carbon black, π, carbon black is uniformly dispersed during crosstalk.
It is necessary to select various cross-talk conditions so as to maintain and manage the cross-wire conditions.

Fishing - In special cases VC must also choose a carbon blank. This not only limits the combination of raw materials to be used, but also impairs other properties that the developer should have in order to achieve high dispersibility of carbon black! 1. Sometimes.

The dispersibility of this carbon is poor.

There is variation in the composition ratio of carbon present in each image agent, and the amount of charge and resistance value vary depending on the composition ratio of carbon. Therefore, the worse the dispersibility of carbon, the higher the illumination rate depending on the developer production lot.
[Objective of the Invention] This invention was developed in view of the above-mentioned circumstances, and it is possible to have carbon black uniformly dispersed within the developer particles and to reduce electrical resistance and charging. Excellent electrical properties such as
The object of the present invention is to provide a developer for electrophotography that has the following properties.

[Outline of the invention]

The outline of this invention for achieving the above object is as follows: Addition 1-
By treating carbon black with an alkaline solution of humic acid, the wetting state of the carbon black with respect to the heated and melted resin binder is improved during crosstalk, thereby achieving high dispersibility of the carbon black. It is a developer for

[Embodiments of the invention]

The electrophotographic developer of the present invention contains carbon black treated with an alkaline solution of humic acid.

The humic acid is, for example, coal with a low degree of carbonization (lignite,
It is a water-insoluble polybasic phenolic carboxylic acid that can be obtained by extracting peat (peat) with an alkaline aqueous solution under heating. Furthermore, when humic acid is produced by oxidizing lignite with nitric acid, nitration also occurs during the oxidation. Therefore, in this invention, when referring to humic acid, it also includes nitrofumic acid.

The alkaline solution of humic acid is % 7) An alkaline aqueous solution of about H9 to 10 contains trophumic acid in humic acid. ),
It can be prepared by adding humates such as potassium humate, sodium humate, ammonium humate, regenerated humic acid, regenerated humates such as their potassium salts, ammonium salts.

The concentration of humic acid in the alkaline solution is 0.1 to 4.
O1llt is preferred, and 1.0 to 2.0w1% is particularly preferred. When the degree of humic acid is within the range of φ11, humic acid can be stably immobilized on carbon black. Also, the concentration of amino acid f 4 Q +11
Even if it is made larger than 1%, the effect of making it larger is small.

The carbon black preferably has a p II of 6.0 to 100. When the p Ji of the car pump rack is within the above range, a strong chemical bond is formed between the alkali group on the surface of the carbon and, for example, nitrofumic acid through an acid-alkali reaction, and the adhesion of nitrofumic acid to the carbon is prevented. It can be stabilized. Commercially available carbon black, Regal 660CR
Z660y made by Cabot), LABE 71030 (RA
VEN 1030 (manufactured by Nhian Carbon Co., Ltd.), RAVEN 420 (RAVEN420; same as above), #
t44 (manufactured by Mitsubishi Kasei), etc. 11-1 These can be suitably used.

Treatment of carbon black with an alkaline solution of humic acid can be carried out by adding carbon black to an alkaline solution of humic acid and stirring the suspension for a predetermined time at room temperature or under heating. After that, the carbon blank is separated by filtration or the like, and then dried.
! 10~HJOy is preferable, and 60~70g is preferable for 1. Yes. If the addition of carbon black (111-) is outside the above range, the processing efficiency may deteriorate. Further, the time required for heating the suspension, stirring, etc. can be determined as appropriate.

It can be prepared by kneading the W-child photographic developer composition 1 of the present invention, the treated carbon black, a resin binder, and optionally fillers, dyes, etc. by a known method. In addition, each component for producing pa:, l can be kneaded in a known blending grade.

Next, examples of this invention will be shown.

Example 1 Humic acid (ciz-o7s; manufactured by Nippon Chill Night Co., Ltd.) 2
To an alkaline solution obtained by adding q to an aqueous solution of p and 119 at 11 Vc, 80 y of carbon black (Sogal 660; manufactured by Cabot Corporation) was added, and the resulting suspension was shaken in a shaker for about 1 hour. Then, the carbon black was impregnated with an alkaline solution of humic acid.

Thereafter, the carbon black was filtered off, and the resulting product was dried by being left at 100° C. for 2 days and nights in a constant temperature dryer.

After treatment, carbon black 60q, resin binder (HIMER 513M-73 []; manufactured by Sanbu Kasei Co., Ltd.) 900 y, and mold release agent (Viscol 660P; manufactured by Ukiyoshi Kasei Co., Ltd.) 40
．． q, f, b were kneaded with 6 rolls heated to 120'Cc, and the resulting mixed wire product was formed into a film. When the film-like molded product was observed under a microscope at a magnification of 400 times, almost no carbon black aggregates were found. Then, the kneaded material was pulverized with VC having an average particle size of 12 pm,
Electrophotographic developer obtained by classification and iron powder carrier (TEF)
V (manufactured by Nippon Tetsuko Co., Ltd.) at a developer mixing ratio of 4%, the charge meter of the developer was 20.5 μc/, q. Then, an image forming apparatus (ppC) loaded with the developer is installed.
Bl)-5504 (manufactured by Toshiba Corporation) was used to perform both printing, and a clear image without "fogging" could be developed.

Comparative Example 1 Carbon black (Sogal 660; manufactured by Gear Pot Co., Ltd.) 59y not treated with an alkaline solution of humic acid, 1 g of humic acid (CJI-07S; manufactured by Nippon Chill Night Co., Ltd.), and a resin binder () 1 Imer-SBM-700; Sanyo Chemical (manufactured by Ukiyoshi Kasei Co., Ltd.) 900y and a molding agent (Viscol 660P; manufactured by Ukisei Kasei Co., Ltd.) 40y were kneaded using six rolls heated to 120°C. The obtained kneaded product was formed into a film. When the molded product was observed under a microscope at 400x magnification, it was approximately 5μ.
Carbon black aggregates and humic acid aggregates were found. When the electrophotographic developer obtained by crushing and classifying the kneaded material into an average particle size of 121 trn was observed under a similar microscope, some transparent particles were found, confirming poor dispersion of carbon black.

Example 2 60 g of carbon black (Sogal 660; manufactured by Capato Co., Ltd.) obtained by the same treatment as in Example 1, 900 q of a resin binder (Niball 2007/; manufactured by Nippon Zeon Co., Ltd.), and a mold release agent (Microcrystalline 220). ; manufactured by Mobil Oil Co.) 40y were kneaded using a 6-roll heated B 140"C#L. The mixed material was crushed and classified to obtain an electrophotographic developer (average particle size 11 μm). This developer was When observed under a microscope at a magnification of 400 times, no transparent developer particles were found.

In addition, the developer and iron powder carrier (TEFV; manufactured by Nippon Tetsuko Co., Ltd.) and f were prepared at a developer mixing ratio of 4% (and the amount of developer in the band was 22 μc/y. , both image forming devices loaded with the developer (ppc-Bn--45
04; manufactured by Toshiba Corporation), it was possible to develop a clear image without "overcasting".

〔Effect of the invention〕

According to the present invention, by treating a carbon blank with an alkaline solution of humic acid, the wetting state of carbon black can be improved, resulting in a good dispersion of carbon black in a resin binder. It has been possible to provide an electrophotographic developer which is easy to manufacture and has excellent charging properties and image properties.

Claims (2)

[Claims] (1) An electrophotographic developer characterized by containing carbon black treated with an alkaline solution of humic acid. (2) The alkaline solution of humic acid is nitrofumic acid,
salts thereof, humates, and regenerated humates; Photographic developer.