JPH04335653A - Yellow liquid developer for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve the visibility of a fine image and to prevent the running and blurring of the image by incorporating a specified disazo yellow pigment and a specified disazo orange pigment as colorants. CONSTITUTION:When a toner based on colorants and resin is dispersed in a highly insulating liq. carrier having a low dielectric constant to obtain a yellow liq. developer for developing an electrostatic charge image, a disazo yellow pigment represented by formula I and one of disazo orange pigments represented by formulae II, III are used as the colorants. In the formulae I, II, X is H, CH3 or CH3O, Y is H, CH3 or CH3O, Z is H or CH3O and R is CH3 or CH3O. In the formula III, R is H or CH3. A known fixer is used as a fixer for the liq. developer without any special restriction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a yellow liquid developer used for developing electrostatic latent images formed by electrophotography or electrostatic recording.

0002

[Prior Art] Color liquid developers used in electrostatic photography such as electrophotography and electrostatic recording are prepared in electrically insulating carrier liquids such as aliphatic hydrocarbon solvents, which have high electrical resistance and low dielectric constant. Toner particles containing a binder, a colorant, an additive, etc. are dispersed in a resin, and the binder is usually a natural or synthetic resin, the colorant is a pigment or dye, and the additive is a metal. A concentrated toner is prepared by mixing a dispersant such as a soap with a carrier liquid and kneading the mixture uniformly, and then diluting this toner in the carrier liquid.

[0003] In order to obtain a color image using such a color liquid developer, an image is formed on an electrophotographic photoreceptor or electrostatic recording paper.
After forming electrostatic latent images according to a conventional method, they are developed using developing solutions of different colors.

A color image is obtained by repeating this process for each color. The color image thus obtained is obtained by piling up toner particles in the liquid developer of each color corresponding to each color of the original image.

[0005] Yellow liquid developer is often used in the final step of development, and therefore has a clear hue and
Greater transparency is required.

Conventional pigments for yellow liquid developers that meet these requirements include C.I. I. Pigment Yellow 12, C. I. Pigment Yellow 13, C. I. Pigment Yellow 14 and other disazo yellows are used, but when monochromatic yellow development is performed using a toner obtained by dispersing such pigments in the manner described above, fine lines and letters become difficult to see. There were problems such as lack of visibility.

On the other hand, in Japanese Patent Publication No. 56-35866, disazo yellow HR (C.I. Pigment Y
A yellow liquid developer using a yellow pigment with a reddish tone such as yellow83) has been proposed.

[0008]

[Problems to be Solved by the Invention] However, although yellow liquid developers using such pigments have excellent visibility, the transparency of the pigments is insufficient, so when used in the final process of development, it is difficult to see the underlying color. As a result of the concealment, there was a problem in that good color reproducibility could not be obtained. Furthermore, there are disadvantages in that image bleeding tends to occur, and when a so-called condenser with a high pigment dispersion concentration is used, caking occurs, and even when the dispersion concentration is low, sedimentation and aggregation are likely to occur.

[0009] Such unfavorable properties of compounds such as Pigment Yellow 83 are due to the P-
This is thought to be due to the presence of the -Cl group introduced at the position.

[0010] The problem to be solved by the present invention is to solve the problem of two colors such as green and red that occur when stacked with cyan and magenta developer.
It is an object of the present invention to provide a yellow liquid developer that does not impair the color reproducibility of the next color and that allows thin lines and characters to be clearly recognized even in monochromatic development, so-called improved visibility.

Another problem to be solved by the present invention is to provide a yellow liquid developer having excellent development properties that does not cause image bleeding or bleeding.

Another problem to be solved by the present invention is to provide a yellow liquid developer which does not cause poor dispersion such as caking and has excellent dispersion stability even when a so-called condenser with a high pigment dispersion concentration is used. The aim is to provide a drug.

[0013]

[Means for Solving the Problems] As a result of extensive research in order to solve the above problems, the present inventors discovered that the problems could be solved by selecting a specific pigment as a coloring agent, which led to the present invention. Ta.

That is, in order to solve the above-mentioned problems, the present invention uses a toner containing a colorant and a resin as main components, which has high insulating properties,
In the electrostatic charge developing solution developer formed by dispersing in a carrier liquid having a low dielectric constant, the colorant is represented by (1) general formula (I).

[0015]

[C4]

[0016] A pigment represented by

001
7] (2) (a) General formula (II)

[0018]

[C5]

(wherein R represents CH3 or CH3O) and (b) general formula (III)

0
020]

[C6]

A yellow liquid developer for electrostatic charge development is provided, which is characterized in that it contains a pigment selected from the group consisting of pigments represented by the formula (wherein R represents H or CH3).

The pigment represented by the general formula (I) used in the present invention is a disazo yellow pigment, and representative examples thereof include disazo yellow AAA (C.I.P.
Pigment Yellow 12), Disazo Yellow AAMX (C.I. Pigment Yellow 1
3), Disazo Yellow AAOT (C.I.Pigme
nt Yellow 14), Disazo Yellow AAO
A (C.I.Pigment Yellow 17),
Disazo Yellow AAPT (C.I. Pigment
Yellow 55), Disazo Yellow 87 (C.I.
．． Pigment Yellow 87), Disazo Yellow 170 (C.I.Pigment Yellow
170), etc. These pigments represented by general formula (I) may be used alone or in combination of two or more.

Further, the pigments represented by the general formulas (II) and (III) are disazo orange pigments, and specifically, Crayon Orange (C.I. Pigment
Orange 15), Balkan Orange (C.I.P.
Pigment Orange 16), Disazo Orange PMP (C.I. Pigment Orange 13)
), disazo orange TMP (C.I.Pigment
Orange 34) and the like. The pigments represented by these general formulas (II) and (III) may be used alone or in combination of two or more.

The ratio of the pigment represented by the general formula (I) used in the present invention to the pigment selected from the group consisting of compounds represented by the general formulas (II) and (III) is 80% by weight. :20 to 99.5:0.5 is preferred, and 90:10 to 99:1 is particularly preferred.

As the fixing agent for the liquid developer used in the present invention, any known fixing agent may be used without particular limitation. Particularly suitable fixing agents include, for example, the following. That is,

(1) A first polymer chain made of a vinyl polymer soluble in an electrically insulating carrier liquid and a vinyl polymer insoluble in the electrically insulating carrier liquid described in JP-A-58-122557. A non-gel-like graft polymer having a molecular structure in which second polymer chains consisting of the following are mutually bonded via urethane bonds, and the entire molecule is insoluble in the electrically insulating carrier liquid.

(2) A cross-linked material which is soluble in an electrically insulating carrier liquid and is obtained by cross-linking a vinyl polymer having an active hydrogen atom capable of reacting with an isocyanate group with a polyisocyanate compound as described in JP-A No. 59-34540. a polymer;
A stranded polymer comprising a vinyl polymer insoluble in the electrically insulating carrier liquid, which is captured by the crosslinked polymer through mutual entanglement of molecular chains.

(3) A crosslinked polymer (soluble in an electrically insulating carrier liquid) obtained by crosslinking a vinyl polymer having a crosslinking-reactive functional group in its molecular side chain as described in JP-A No. 63-208866 ( (hereinafter referred to as a crosslinked polymer), and a vinyl copolymer insoluble in the electrically insulating carrier liquid, which is obtained by copolymerizing a vinyl monomer having a basic nitrogen atom or an amide group in the molecule and a vinyl acetate monomer, The vinyl copolymer that is insoluble in the electrically insulating carrier liquid is a chain polymer that is captured by the crosslinked polymer due to mutual entanglement of molecular chains.

(4) The applicant of this application filed Japanese Patent Application No. 1-1625
An acrylic copolymer soluble in an electrically insulating carrier liquid consisting of methyl methacrylate and an acrylic ester or a long-chain alkyl ester of methacrylic acid, filed as No. 19, and having a basic nitrogen atom or an amide group in the molecule. consisting of a vinyl copolymer insoluble in the electrically insulating carrier liquid formed by copolymerizing a vinyl monomer and a vinyl acetate monomer,
The vinyl polymer insoluble in the electrically insulating carrier liquid is a chain polymer that is captured by the crosslinked polymer due to mutual entanglement of molecular chains.

The amount of these fixing agents used relative to the pigment is usually preferably in the range of 10 to 300% by weight.

Examples of the electrically insulating carrier liquid include hexane, pentane, octane, nonane, decane, undecane, and dodecane, as well as products such as Isopar G, H, K, L, and M manufactured by Esso Standard Oil Co., Ltd. Various aliphatic hydrocarbon solvents, such as organic solvents sold under can be used.

The liquid developer of the present invention may further contain auxiliary agents such as a charge control agent and a dispersion stabilizer, if necessary. As auxiliary agents such as charge control agents and dispersion stabilizers, those normally used in liquid developers for electrostatic charge development can be used without particular limitation, such as cobalt naphthenate, copper naphthenate, copper oleate, Examples include cobalt oleate, zirconium octylate, cobalt octylate, and polymers of aluminum oxide acylate.

The liquid developer according to the present invention comprises the pigment represented by the general formula (I), the general formulas (II) and (III), and the pigment represented by the general formula (I).
), a fixing agent, an electrically insulating carrier liquid, and, if necessary, a mixture of auxiliary agents such as a charge control agent and a dispersion stabilizer. , evenly dispersed with an attritor etc.
The concentrated toner is prepared as a concentrated toner having a nonvolatile content of about 0.1 to 2% by weight, and when used as a liquid developer, the concentrated toner is diluted with the electrically insulating carrier liquid so that the nonvolatile content is about 0.1 to 2%. do it.

[0034]

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto. In the following examples, "parts" and "%" represent "parts by weight" and "% by weight," respectively.

(Production of fixing agent) ■Fixing agent A 150 parts of "Isopar H", 15 parts of methyl methacrylate and 85 parts of 2-ethylhexyl methacrylate were placed in a glass container equipped with a reflux condenser, and the contents were stirred. while 80
After heating to °C, 0.5 part of benzoyl peroxide was added while maintaining the same temperature, and the mixture was reacted for 6 hours. Furthermore, 90℃
The reaction was continued for 2 hours. After cooling, remove the contents and
A viscous polymer having a viscosity of 30 Stokes was obtained.

131 parts of the above polymer were charged into the same reaction vessel as above, and 152 parts of "Isopar G", 40 parts of vinyl acetate, 5 parts of N-vinylpyrrolidone and 0.45 parts of azobisisobutyronitrile were added. In addition, the temperature was raised to 80°C,
The reaction was carried out at 80° C. for 6 hours to obtain a white fixing agent dispersion having a non-volatile content of 30%. The fixing agent dispersion thus obtained was designated as "fixing agent A."

■ Fixing agent B 30.0 parts of lauryl methacrylate, 22.0 parts of butyl methacrylate, 46.6 parts of butyl acrylate, 0.4 part of hydroxypropyl methacrylate, 1.0 part of methacrylic acid, "Perbutyl D" 1.0 parts of ``Polymerization Catalyst'' (manufactured by NOF Corporation) and 100 parts of ``ISOPAR G'' were charged into a reaction vessel equipped with a nitrogen gas introduction tube, a stirrer, and a cooling tube, and the temperature was raised to 120°C. Non-volatile content after time reaction: 48.8%
, a polymer having an average molecular weight of 220,000 was obtained.

Next, the temperature was lowered to 70°C, and 0.62 parts of isophorone diisocyanate and 0.05 parts of stannous octylate were added.
After adding weight and 0.6 part of "Isopa G" and carrying out a urethanization reaction at 70°C for 4 hours, it was cooled to form an intermediate containing isocyanate groups with a non-volatile content of 48.6% and an NCO content of 0.6%. A body solution was obtained.

[0039] 106 parts of the solution of the intermediate was charged into the same reaction vessel as above, and further 180 parts of "Isopar G", 0.4 parts of hydroxypropyl methacrylate, 46.1 parts of methyl methacrylate, and azobisisobutylene were added. 0.25 part of lonitrile was added, the temperature was raised to 80°C, and the mixture was reacted at 80°C for 5 hours to obtain a graft polymer solution with a nonvolatile content of 29.2% and an NCO content of 0%. This graft polymer was a white latex in which the first polymer chain and the second polymer chain were bonded by about 6 urethane bonds per molecule. The fixing agent dispersion obtained in this way is called "fixing agent B".
And so.

■Fixer C 80 parts of lauryl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 10 parts of N-vinylpyrrolidone, 1 part of di-tert-butyl peroxide, and 148 parts of "Isoper G" were mixed with nitrogen gas. The mixture was charged into a reaction vessel equipped with an introduction tube, a stirrer, and a cooling tube, and the temperature was raised to 130°C.
The reaction was carried out at 0° C. for 6 hours to obtain a solution of the first polymer. Next, the temperature was lowered to 80°C, 1.5 parts of isophorone diisocyanate, 0.03 parts of di-n-butyltin dilaurate, and 2 parts of "Isopar G" were added, and a urethane reaction was carried out at 80°C for 2 hours. Thereafter, the mixture was cooled to obtain a crosslinked polymer solution with a nonvolatile content of 38.2%.

[0041] 131 parts of the crosslinked polymer was charged into the same reaction vessel as above, and further 152 parts of "Isopar G",
After adding 5 parts of 2-hydroxypropyl methacrylate, 40 parts of methyl methacrylate, 5 parts of β-methacryloxyethyl phthalate and 0.25 part of azobisisobutyronitrile, the temperature was raised to 80°C. The mixture was reacted for 6 hours to obtain a white fixing agent dispersion having a non-volatile content of 30%. The fixer dispersion thus obtained was designated as "Fixer C".

(Example 1) "Shimla Fast Yellow GRF" (
Yellow pigment C. manufactured by Dainippon Ink Chemical Industries, Ltd. I. Pigme
nt Yellow13) 13 parts "Shimla First Pyrazolone Orange G" (CI Pigment manufactured by Dainippon Ink Chemical Co., Ltd.)
Orange 13) 0.5 part
Fixer C"

90 parts “Zirconium naphthenate”

Part 2 “Isopar G
” (Aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.)
150 parts of the above mixture was dispersed in a ball mill for 24 hours, and then diluted with "Isopar G" so that the nonvolatile content was 12% to obtain a concentrated toner. This concentrated toner did not cause caking and was stable even after storage for 6 months. Further, 100 parts of the above concentrated toner was diluted with 2000 parts of "Isopar G" to obtain a liquid developer.

Next, an electrostatic latent image was formed on electrostatic recording paper using a color electrostatic plotter "EP-4010" manufactured by Seiko Electronic Industries, Ltd., and developed with the liquid developer described above.
A yellow image with no image blurring and good visibility of fine lines was obtained. Further, the color reproducibility of secondary colors green and red was also good.

(Example 2) "Shimla Fast Yellow RF"
(Yellow pigment C.I.Pi manufactured by Dainippon Ink Chemical Industries, Ltd.
gment Yellow 55) Part 12 “
Shimla First Orange V” (CI Pigment manufactured by Dainippon Ink and Chemicals Co., Ltd.)
0range 16) 0.3 parts “Fixer B”

100 parts "Copper naphthenate"

Part 2 “Isopar G”

After dispersing 100 parts of the above mixture in a ball mill for 24 hours, a concentrated toner having a non-volatile content of 13% was obtained in the same manner as in Example 1. This concentrated toner did not cause caking even after being stored for 6 months and was stable. Furthermore, the concentrated toner 8
A liquid developer was prepared by diluting 0 part with 2000 parts of "Isopar G" and developed using Seiko Electronics' color electrostatic plotter "EP-4010" in the same manner as in Example 1. There was no image bleeding. , and a yellow image with good visibility of thin lines was obtained.

(Example 3) In Example 2, "Shimla Fast Yellow RF" was replaced with "Shimla Fast Yellow RF".
Lionol Yellow FFR” (yellow pigment CI Pigment Yellow 87 manufactured by Toyo Ink Co., Ltd.) was used.
Instead of "Shimla Fast Orange V", "Permanent Orange RL" (orange pigment manufactured by Hoechst)
C. I. A concentrated toner and a developer were prepared in the same manner as in Example 3, except that Pigmen Orange 34) was used.

(Example 4) In place of "Shimla Fast Yellow GRF" as the colorant in Example 1,
"Permanent Yellow G" (yellow pigment C manufactured by Hoechst)
．． I. A concentrated toner and developer were prepared in the same manner as in Example 1, except that Pigment Yellow 14) was used.

(Comparative Example 1) A concentrated toner and developer were prepared in the same manner as in Example 1, except that "Shimla Fast Pyrazoloone Orange G" was not used.

(Comparative Example 2) In Example 2, "PV Fast Yellow HR" (yellow pigment manufactured by Hoechst) was used as the coloring agent instead of "Shimla Fast Yellow RF" and "Shimla Fast Orange V". A concentrated toner and developer were prepared in the same manner as in Example 2 except for this.

Each of the developers obtained in Examples 1 to 4 and Comparative Examples 1 to 2 was evaluated for visibility of fine line images, dispersibility of concentrated toner, and presence or absence of image bleeding, and the results are shown in Table 1. Ta.

[0050]

[Table 1]

In the table, the evaluation of visual recognition of fine line images and image blurring was performed using a color electrostatic plotter "EP-4" manufactured by Seiko Electronics Co., Ltd.
An image developed using "010" was observed. Dispersibility was evaluated by observing the state of the concentrated toner after it had been stored for 6 months.

[0052]

According to the liquid developer of the present invention, it is possible to provide excellent visibility of fine line images and excellent developed image quality without image deletion or bleeding.

Further, the liquid developer of the present invention exhibits excellent dispersion stability without causing poor dispersion such as caking even when the pigment dispersion concentration is high as in the case of concentrated toner.

Claims (1)

[Claims] [Claim 1] A yellow liquid developer for electrostatic charge development comprising a toner containing a colorant and a resin as main components dispersed in a highly insulating and low dielectric constant carrier liquid, wherein the colorant has the general formula (1) I) [Chemical 1] (wherein, X represents H, CH3 or CH3O, and Y represents H
, CH3 or CH3O, and Z represents H or CH3O. ) and (2)(a) general formula (
II) A pigment represented by [Chemical formula 2] (wherein R represents CH3 or CH3O) and (b) a pigment represented by the general formula (III) [Chemical formula 3] (wherein R represents H or CH3) The liquid developer characterized in that it contains a pigment selected from the group consisting of the following pigments.