JPH012065A - Color liquid developer for electrostatography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to color liquid developers for electrostatography. - [Prior art] Color liquid developers used for electrostatic photography such as electrophotography and electrostatic recording include several colors of pigments, rosin, linseed oil, soybean oil, modified alkyd resin, styrene-butadiene copolymer, and acrylic resin. These resins or oils are obtained by pulverizing and dispersing each color into a highly insulating and low dielectric constant carrier liquid such as an aliphatic hydrocarbon.

When a color image is obtained using such a set of developers, an electrostatic latent image is formed on electrophotographic paper, electrostatic recording paper, etc. by a conventional method, and then this is formed with a liquid developer. A color image is obtained by repeating the developing process for each color and sequentially overlapping toners of several colors.

As mentioned above, in color electrostatic photography, because several colors of toner are superimposed, fog accumulates in the background area. The color image thus obtained had low contrast and was not fully satisfactory.

In color electrostatic photography, for example, there is a method in which toner is layered in the order of black, cyan, magenta, and yellow, and fogging of magenta toner is generally noticeable.

Azo lake pigments such as Carmine 6B are used as pigments for magenta toners due to their clear purplish tone and excellent transparency, but toners obtained by dispersing azo lake pigments using the method described above All had poor background fog.

In addition, dyeing latex with a dye and applying it to toner is also being considered (Japanese Patent Laid-Open Nos. 45-25878, 1983).
-10619, etc.), which has the problem of causing background fog if the dye that has not penetrated into the latex is not completely removed.

[Objective] An object of the present invention is to provide a magenta liquid developer suitable for overlapping development type color electrophotography, which eliminates the above-mentioned drawbacks.

[Structure] The present inventor has conducted repeated research in order to solve the above problems, and has found that the problem can be solved by selecting a specific pigment as a coloring agent, and has completed the present invention.

That is, the present invention provides a liquid developer comprising a toner mainly composed of a pigment and a resin dispersed in a carrier liquid, in which the pigment has the following formula: %. This is a color liquid developer for electrostatic photography characterized by the following. ' The pigment used in the present invention is a naphthol As-based insoluble azo pigment represented by the above formula.

A typical example of this is as follows.

In order to prepare a liquid developer using such a pigment, 1 to 10 parts by weight of this pigment, 1 to 50 parts by weight of a binder, and 40 to 100 parts by weight of a carrier liquid are mixed in an attritor, a ball mill,
A concentrated toner may be obtained by cross-dispersing the toner using a sand mill, and if necessary, this may be diluted with a similar carrier liquid.

As the binder here, alkyd resin, rosin-modified phenol formaldehyde resin, polyhydric alcohol ester of hydrogenated rosin, polyacrylic or polymethacrylic ester resin, styrene resin, chlorinated rubber, etc. are used, but in particular, the following - formula (n) [However, R3 is hydrogen or methyl group, R4 is -COOC,
82F1+1 or -〇〇〇〇, H2n+1 (n is 6~
20 integers). ] A monomer represented by acrylic acid, methacrylic acid, vinylpyridine, the following formula (III) [However, R5 is hydrogen or a methyl group, R6 is -COOCnH2n+1 or -
0COC, H2n+i (n is an integer from 1 to 5). ] A monomer represented by the following formula (IV) [However, R
7 is hydrogen or methyl group, R8 is -N (Ct-13>2,
-N(C2H5)2 or -OH. It is effective to use a copolymer (including a block copolymer) with one or more heptamers selected from the following heptamers and ethylene glycol dimethacrylate. - The appropriate proportion of the vinyl monomer component represented by formula (n) in the copolymer is about 30 to 95% by weight.

These binders may be used as necessary (natural resins such as ester gum, softened rosin, natural resin-modified maleic acid resin, natural resin-modified phenol resin, natural resin-modified polyester resin, natural resin-modified pentaerythritol resin, epoxy resin). Natural resin-modified thermosetting resins, such as, may be added.

The carrier liquid used in the developer of the present invention is preferably an aliphatic hydrocarbon or a derivative thereof.

Specific examples include paraffinic or isoparaffinic hydrocarbons (Isovert 1 manufactured by Ethane Co., Ltd.,
Isopar G1 Isopart 1 Isopar, NO, 6
sorbetso 100, etc.), ligroin, n-hexane,
N-hebutane, 1so-octane, n-octane, carbon tetrachloride, trichlorotrifluoroethane, cyclohexane, etc. may be used alone or in combination of two or more.

Hereinafter, the present invention will be explained in more detail in Examples.

Examples 1 to 5 A mixture having the composition shown in Table 1 below was placed in a ball mill and dispersed for 24 hours to prepare a concentrated toner. Thirty parts of this concentrated toner was diluted with Isopar 019 to prepare a liquid developer.

Subsequently, when this liquid developer was used for printing with an electrostatic printer plotter V-80 (manufactured by Versatic Co., Ltd.), an image with high image density and no background fog was obtained. The evaluation results are shown in Table 2 below.

Comparative Example A comparative liquid developer was prepared in the same manner as in the example except that the pigment in the example was changed to brilliant carmine 6B represented by the following formula (V).

When printing was performed using this liquid developer in the same manner as in the example, the image density was low and fog was noticeable in the background area.

...-mathematical formula, (V) Table 1 Table 2 The concentration was measured by Macbeth reflex II.

[Effects] As is clear from the comparison between Examples and Comparative Examples, the liquid developer of the present invention has no background fog, has high image density, and has no color overlap. This has remarkable effects such as being able to improve the contrast when a color image is obtained by development.

In addition, it goes without saying that the present invention can be applied to a color liquid developer for electrostatic photography for obtaining monochromatic (reddish) color images by electrostatic photography.

Claims (1)

[Claims] A liquid developer comprising a toner mainly composed of a pigment and a resin dispersed in a carrier liquid, in which the pigment has the following general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( I ) [Formula Inside, R is hydrogen, ▲There are mathematical formulas, chemical formulas, tables, etc.▼
(A, B and C are -CH_3, -Cl, -NO_2, -OCH_3,
-NH・CO・CH_3, -OC_2H_5, H) X and Y are -CH_3, -Cl, -NO_2, -OCH_
3, -SO_2・NH・CH_3, H, -SO_2・N
(C_2H_5)_2, -CO・▲There are mathematical formulas, chemical formulas, tables, etc.▼(R_2:
-CH_3, -Cl, -CONH_2, H). ] A color liquid developer for electrostatic photography, characterized by the following: