JPS59195248A - Positively chargeable toner - Google Patents

Abstract

PURPOSE:To facilitate positive triboelectrification through friction with carrier particles and to obtain toners good of not only black but other colors by incorporating aminopyrine as an electrostatic charge controller. CONSTITUTION:Aminopyrine is incorporated as a charge controller in an amt. of 0.1-15wt% of a binder resin, such as polystyrene. Aminopyrine is obtained as a white powder, well dispersed into a binder resin, and easily subjected to positive electrification good in uniformity by friction with carrier particles, such as iron powder. As a result, not only black but other color positively chargeable toners can be obtained, and a fog-free good color image can be formed by using such a developer for electrophotography and electrostatic printing, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a two-component developer used in electrophotography or electrostatic printing, and particularly to a toner that is positively charged by frictional contact with carrier particles.

(b) Background of the technology In electrophotography or electrostatic printing, an optical pattern is projected onto a charged photoconductor surface (generally referred to as a photocondrum, a cylindrical surface on which a photoconductor layer is provided). At this time, the developer, that is, toner, which is electrostatically attracted by the residual charge in the shaded area on the surface of the photocon drum, is transferred to the recording paper to form an image.

In the above, if the residual charge on the surface of the photocon drum is of negative polarity, the toner is charged to positive polarity in advance.

The composition of such a toner includes a charge control agent that determines the charge polarity of the toner, a coloring agent that determines the color of the printed pattern, and
It consists of a binder (generally a resin) to firmly adhere these to the printing paper, and the charge control agent and colorant are dissolved or dispersed in the resin and then ground into a fine powder with a diameter of about 10 μm. Prepare.

(C1 Prior Art and Problems) Examples of charge control agents added to conventional positively charged toners include fatty acid-modified nigrosine dyes and polyamine resins (see JP-A-51-9456).

However, since the former itself is black, it also functions as the coloring agent and cannot be applied to color toners other than black, and the latter is difficult to uniformly disperse in the binder resin. Large variations in the charge amount of toner powder have been a problem, and there has been a need for a charge control agent that has good dispersibility in a binder resin and is suitable for color printing.

(d1 Purpose of the Invention The present invention utilizes the positive chargeability of aminopyrine and its good compatibility with the binder resin to create a positively charged black toner in a toner comprising a binder resin, a colorant, and a charge control agent. An object of the present invention is to provide a positively charged color toner other than black.

fe) Structure of the Invention The present invention provides aminopyrine obtained as a white powder as a carrier particle (when toner particles are electrostatically adsorbed on the surface of the photocondrum, the toner particles are transported from the developing device to the vicinity of the surface of the photocondrum. It is a particle that plays a role, and is easily charged to a positive polarity by frictional contact with iron powder (iron powder is used as a carrier particle in the case of the so-called magnetic brush method), and has good dispersibility in the binder resin. By using this, a positively charged toner suitable for color printing can be obtained.

(f) Examples of the invention Examples of the present invention will be described in detail below.

As mentioned above, the composition of the toner can be roughly divided into a binder resin, a charge control agent, and a colorant, and most of the conventionally known binder resins can be used as the binder resin in the toner of the present invention. For example, polyethylene resin, polypropylene resin, polystyrene resin, copolymer of styrene and acrylic ester, copolymer of styrene and butadiene,
Polyamide resins, polyvinyl chloride resins, polymethyl methacrylate resins, polyurethane resins, epoxy resins, phenol resins, and the like can be used alone or in combination of two or more.

0 parts of aminopyrine per 100 parts by weight of the above binder resin.
．． It can be added in an amount of 1 to 15 parts by weight.

That is, when the amount of aminopyrine added is 0.1 parts by weight or less, the charging property of the aminopyrine becomes insignificant, while when it is 15 parts by weight or more, uniform dispersion in the binder resin becomes difficult. This is because variations occur in the amount of charge on the toner.

The toner according to the present invention may contain conventionally known colorants. For example, carbon powder and nigrosine dye are used to produce a black toner, and rhodamine pigment is used to produce a red toner. or quinacridone pigment, copper phthalocyanine pigment or anthracene derivative dye in the case of producing a blue toner, and colorants such as benzidine yellow in the case of producing a yellow toner, etc., are kneaded together with a binder resin, etc., and then finely powdered. By pulverizing it into shapes, toners of various colors can be obtained.

Furthermore, for the toner of the present invention, a lubricant and other properties are provided to improve the fluidity of the toner during frictional contact with the carrier particles or when the toner particles are electrostatically attracted to the surface of the photocon drum. There is no problem even if a modifier is included.

The toner of the present invention can be manufactured using conventionally known techniques. That is, aminopyrine, which is a charge control agent, is added to the binder resin, and a colorant and other additives are added thereto, and then thoroughly kneaded using a hot roll or a kneader. Next, coarse pulverization is performed using a rotoplex or hammer mill, followed by fine pulverization using a jet mill or the like.

Finally, particles of 5 to 20 μm are collected using an air classifier to obtain toner.

Specific examples of the present invention will be described below.

Example 1 Binder resin: Polystyrene resin (Pico Stysoku D125 manufactured by Esso) ... 100 parts by weight Charge control agent: Aminopyrine ... 3 parts by weight Coloring material: Carbon Blasof (Blank Purlz, manufactured by Capo Soto) ...
3 parts by weight With the above composition, a black toner with an average particle size of 10 μm was obtained using the manufacturing method described above. 3 parts by weight of the toner and surface-treated spherical iron powder (manufactured by Kanto Denka Co., Ltd. 5T-2)
A developer was prepared by mixing 97 parts by weight of 00). When a printing test was carried out using a laser printer using this developer, a black image with no "fogging" in the background was obtained. ) was measured using +17.3μ
C/g was obtained, and it was confirmed that the value was within the range generally considered to be suitable for practical use.

Example 2 Binder resin: Epoxy resin (Epicoat # manufactured by Shell Chemical Co., Ltd.
1004)... 100 parts by weight Charge control agent Niaminopyrine... 5 parts by weight Colorant: Quinacridone pigment (Shinkasha manufactured by DuPont)
5 parts by weight With the above composition, a red toner with an average particle size of 10 μm was obtained using the manufacturing method described above. Example 1 from the toner. A developer was prepared in the same manner as above, and a similar printing test was conducted, and a good red image with no "fogging" in the background was obtained. Further, when the amount of charge of this developer was measured using the same device as above, it was found to be +15.2 μC/g, which was confirmed to be within a practically appropriate range.

(g) Effects of the Invention According to the present invention, it is possible to produce a positively charged toner with good uniformity of charge amount, and the color of the positively charged toner can be arbitrarily selected according to the selection of the coloring material. This has the effect of making it possible to provide not only positively charged toner but also positively charged toner for color printing.

Claims (2)

[Claims] (1) A positively charged toner containing aminopyrine as a charge control agent. (2) The positively charged 1-ner according to claim 1, wherein the content of the aminopyrine is in the range of 0.1 to 15 parts by weight per 100 parts by weight of the binder resin.