JPS5915256A - Dry type electrophotographic positive chargeable toner - Google Patents

Abstract

PURPOSE:To enhance image quality, by using a specified compd. superior in polarity control action for a dry type electrophotographic toner contg. a resin as a main component. CONSTITUTION:The toner contains a small amt. of compd. strong in polarity control action represented by one of formulae I -III in which R, R<1> are each H, lower alkyl, or the like; R<2>, R<3> are each aryl, arylalkenyl, or the like represented by formula 1-3; R<4> is H, lower dialkylamino, or the like; n is an integer of 0-3; and m is an integer of 1-4. A preferable amt. of this compd. to be added is >=0.1wt% of the toner resin component. The toner of this invention is formed by mixing the resin with said compd. represented by the formulae, when needed, further together with colorant, modifier, etc., kneading them at a temp. not below the m.p. of the resin, and pulverizing them into a desired particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positively charged toner for a developer used in dry electrophotography, and more particularly to a positively charged toner that improves image quality by using a compound with an excellent polarity control effect.

When a developer is used for a long time in electrophotography, collisions between toner particles and carrier particles, and furthermore, collisions between these developer particles and the surface of the photoreceptor, cause mutual deterioration, resulting in changes in image density and the occurrence of a cannonball phenomenon. Detracts from image quality. Further, as the toner is used, the amount of toner adhering to the surface of the photoreceptor having the electrostatic latent image increases, increasing the image density and also increasing the background density, reducing the contrast between the image and the background.

In addition, for positively charged toner, resins with strong polarity control effects,
Coloring agents are used, but for example, in the case of resins with certain functional groups introduced, unpleasant odors may occur due to the functional groups during heat fixing, and polarity control may occur under high humidity. The effect decreases and the desired effect cannot be obtained. Furthermore, in the case of colorants, there are drawbacks such as not only insufficient polarity control action being obtained unless a large amount is used, but also the use of the colorant restricts the toner resin to a narrow range. .

An object of the present invention is to solve the above-mentioned conventional drawbacks, and in particular, a compound having a strong polarity control effect represented by any of the following general formulas (I), (■), and (■) is added to a toner. The object of the present invention is to provide a positively charged toner for dry electrophotography that can stably provide clear images with excellent image quality by containing a small amount of the toner.

R: a group selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, and halogen.

R1: a group selected from the group consisting of hydrogen, a lower alkyl group, a lower alkokene group, and a halogen.

R2, R3: Azo group, imino group or The same or different groups selected from the group consisting of alkenyl groups.

(In the formula, R4 is a group selected from the group consisting of hydrogen, a lower dialkylamino group, a nitro group, a lower alkoxymorpholino group, a piperidino group, a halogen group, and a julolidino group, and n is an integer of 0 to 3. , m is an integer of 1 to 4.) To explain the toner of the present invention in more detail, the compound represented by the above general formula is a coloring agent that has a strong polarity control effect, and even a small amount may impair various properties. Not only does it have a sufficient polarity control effect, but it also does not generate unpleasant odors during fixing or impair its effects due to environmental changes such as changes in temperature and humidity. The amount of the compound used is 0.1% by weight or more, preferably 0.3% by weight based on the toner resin component.
% by weight or more.

The resin used together with the above compound is not limited to a narrow range like conventional polarity control agents, and
Any resin used in ordinary dry electrophotographic toners can be used. These resins are appropriately selected in consideration of the characteristics usually required for a toner, such as adhesiveness, preservability, fluidity, and pulverizability. Examples of shells include epoxy resin, phenol resin, acrylic resin, styrene resin,
Styrene-butadiene resin. Examples include alkyd resin, sax, rosin, cellulose resin, acetal resin, vinylidene resin, and maleic acid resin.

In order to produce the toner of the present invention using the above components, a resin and a compound represented by the above general formula are added according to conventional methods, and if necessary, conventionally known colorants, modifiers, etc. are added. The mixture is kneaded at a temperature higher than the melting point of the resin, and then ground to a desired particle size.

The present invention will be explained below with reference to Examples.

Example 1 Polystyrene (Picolastic D-125 manufactured by Esso Standard Oil Co., Ltd.) 100 parts by weight carbon black
A toner composition consisting of 15 parts by weight was melt-kneaded in a roll mill, cooled, pulverized in a jet mill, and classified (to obtain toner particles with a particle size of 5 to 25 μm).

3.5 parts by weight of the toner thus obtained and 150 parts by weight
When 96.5 parts by weight of an iron powder carrier of ~250 mesh down was mixed to positively charge the toner and the electrostatic latent image on the photoreceptor was developed in a conventional manner, a clear image was obtained.

Examples 2 to 3 Positively charged toner was obtained in the same manner as in Example 1 except that the toner had the following composition, and the electrostatic latent image on the photoreceptor was developed, and satisfactory results similar to those of Example 1 were obtained. or obtained.

Example 2: Styrene-acrylinoleic acid copolymer (Himer SBM-7
3 Sanyo Chemical Co., Ltd.) 100 parts by weight carbon black
10 parts by weight Example 3: Borisdylene (Picolastic) D-125 manufactured by Esso Standard Oil Co., Ltd.) 70 parts by weight Epoxy resin (Ebicoat 1004 manufactured by Shell Chemical Co., Ltd.) 30 parts by weight Carbon black 7 parts by weight or more As is clear from the results Images obtained using the toner of the present invention had extremely excellent clarity. In addition, the resulting image is not only fixed without producing an unpleasant odor unlike conventional polarity control agents, but also provides clear images with stable quality even during long-term copying.

Example 4 Styrene-acrylic acid copolymer (Himer SBM600
, manufactured by Sanyo Chemical Co., Ltd.) 100 parts by weight carbon black
A composition consisting of 13 parts by weight was processed in the same manner as in Example 1 and developed as a dry toner, resulting in a clear image.

Example 5 A composition consisting of 100 parts by weight of polystyrene (Picolastic) 125) and 10 parts by weight of carbon black was treated in the same manner as in Example 1 and developed in the same manner as a dry toner, resulting in a clear image.

Claims (1)

[Scope of Claims] A toner for dry electrophotography whose main component is a resin, characterized by containing at least one compound represented by any one of the following general formulas (■), (■), and (■). Positively charged toner for dry electrophotography. R: a group selected from the group consisting of hydrogen, a lower alkyl group, a lower alkoxy group, and a halogen. R1: a group selected from the group consisting of hydrogen, a lower alkyl group, a lower alkoxy group, and a halogen. R2, R3: an azo group, an imino group, and a substituent selected from aryl groups, arylalkenyl groups, substituted aryl groups, and substituted arylalkenyl groups represented by general formulas (1) to (3); lζ same or different groups selected from the group consisting of alkenyl groups; (In the formula, R4 is a group selected from the group consisting of hydrogen, lower dialkylamino group, nitro group, lower alkoxymorpholino group, piperinodino group, halogen group, and julolidino group, and n is 0 to 3. (Integer, m is an integer from 1 to 4.)