JPS589417B2 - Manufacturing method of colorant for wet electrophotographic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a colorant for wet electrophotographic toner by a flushing method.

A method for producing a colorant for wet electrophotographic toner involves kneading a water-containing paste consisting of organic pigments such as phthalocyanine green and alkali blue, carbon black, and water with an organic solvent solution of a resin, and replacing the water in the paste with the organic solvent. The organic pigment and carbon black are coated with a resin, water and organic solvent are distilled off to form a cake, and finally this cake is crushed.

A so-called flushing method is known.

The colorant obtained in this way is mixed with other resins and then crushed to make toner, which is then made into a highly insulating material (electrical resistance 1010Ω).
cm) and a low dielectric constant (relative dielectric constant of 3 or less), it is uniformly dispersed in an aliphatic hydrocarbon carrier liquid and used as a developer.

However, if a colorant resin that is soluble in the carrier liquid is used, many of the soluble resins lower the electrical resistance of the carrier liquid, making the toner polarity unstable or even reversing it, resulting in image density. The image quality may deteriorate, or background stains may occur, making it impossible to form a clear image.

Therefore, colorant resins that are insoluble or poorly soluble in the carrier liquid are generally used.

However, in the case of this type of resin, unless the compatibility with organic pigments and formulation balance are taken into consideration when manufacturing the colorant, or troublesome measures such as long-term dispersion are taken during the manufacturing of the toner, the process of dispersion will increase over time. At the same time, dispersion stability such as toner sedimentation and agglomeration in the developing solution is reduced, and the resulting image lacks drying properties, that is, primary fixing properties, and thus suffers from defects such as image transfer.

The purpose of the present invention is to use a specific resin that has relatively high solubility in a carrier liquid, but does not cause a decrease in image density or background smearing, and which does not require any troublesome means. An object of the present invention is to provide a method for producing a colorant.

That is, the present invention provides a coloring agent for wet electrophotographic toner, which involves kneading a water-containing paste consisting of an organic pigment, carbon black, and water with an organic solvent solution of a resin, distilling off the water and organic solvent, and then pulverizing the resulting cake. The manufacturing method is characterized in that the resin used is one selected from the group consisting of natural resin-modified polyester resin, aromatic hydrocarbon thread petroleum resin, and aliphatic hydrocarbon petroleum resin.

The resin used in the present invention has relatively high solubility in aliphatic hydrocarbons, which are carrier liquids for wet-type electrophotographic developers, but even when dissolved, developers such as conventionally known soluble resins Since the particle size of the toner in the developing solution can be reduced without reducing the electrical resistance of the toner, sedimentation and aggregation are less likely to occur, and therefore dispersion stability can be improved.

Commercially available resins used in the present invention include FIM-9, a natural resin-modified polyester resin manufactured by Tokushima Essential Oil Co., Ltd.
5, RM-105, etc., and aromatic hydrocarbon petroleum resins such as Petrosine #80 and #100 manufactured by Mitsui Petrochemicals Co., Ltd.
, #120, #130, #150, KS, etc.), and for aliphatic hydrocarbon petroleum resins, Hiretsu G-100X, T-100X1P-100L, P-1 manufactured by Mitsui Petrochemical Co., Ltd.
00L-M, R-100X, FTFt-6090, 61
There are 00, 6110, Taku-S A-100, etc.

The type of organic pigment, crosstalk conditions, distillation conditions, pulverization conditions, etc. may all be the same as conventional ones.

Example 1 500 g of water, 30 g of carbon black (Printex G), and 20 g of alkaline blue were thoroughly stirred with a flasher, and then 600 g of Petrosin #80 was added to it.
(10% toluene solution) is added and further kneaded.

Then, the water and toluene are distilled off by heating and reducing the pressure to form a cake, which is ground in a stone mill to a 0.08 to 0.
A 15μ particle size colorant was obtained.

Examples 2 to 4 Colorants were produced in the same manner as in Example 1, except that the carbon black, organic pigment, and resin listed in the table below were used.

The particle size of each colorant is as indicated.

Note) *1: Carbon black and organic pigment of the corresponding examples were used.

*2: 10% toluene solution *3: Rosin modified maleic acid resin *4: Same as above

Claims (1)

[Claims] 1. A method for producing a colorant for wet electrophotographic toner, which involves kneading a water-containing paste consisting of an organic pigment, carbon black, and water with an organic solvent solution of a resin, distilling off the water and organic solvent, and then pulverizing the resulting cake. A coloring agent for a wet electrophotographic toner, characterized in that the resin is one selected from the group consisting of a natural resin-modified polyester resin, an aromatic hydrocarbon thread petroleum resin, and an aliphatic hydrocarbon petroleum resin. manufacturing method.