JPH05188656A - Yellow liquid developer for electrostatic process - Google Patents

Abstract

PURPOSE:To obtain a developer free from the fluctuation of charge quantity and stable in long preserving and running and suitable to obtain a full color by using a pigment expressed by a specific formula as a coloring agent. CONSTITUTION:The subject developer is made by dispersing a toner containing mainly a coloring agent, a resin in a carrier liquid and the pigment expressed by the formula is used as the coloring agent. In the formula, each of R<1> and R<2> is hydrogen atom. halogen atom, lower alkyl group or lover alkoxy group. The pigment is insoluble in the carrier liquid, but becomes stable in the adsorption of ion dissociated from a charge controlling agent by introducing a polar group, that is amide group, in the molecular structure of the pigment. In the producing of the pigment, a coupling component is produced by making 3- amino-4-methoxy benzoic acid amide dissolved in aceton to react with diketen in the presence of pyridine or the like. The coupling reaction is executed by dissolving the coupling component in an alkaline solution and adding a diazo aq. solution little by little to couple and heating after making weak acidic with acetic acid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yellow liquid developer for electrostatic photography, and more specifically, it can be formed by electrostatically attaching toner particles to an electrostatic latent image formed on an electrophotographic photoreceptor or an electrostatic recording material. The present invention relates to a yellow liquid developer for electrostatic photography used in a process of visualizing and superimposing colors.

[0002]

2. Description of the Related Art In order to obtain a full-color image by an electrophotographic method or an electrostatic recording method, an electrostatic latent image is formed on an electrophotographic photosensitive member, electrostatic recording paper or the like by a conventional method, and primary colors obtained by a subtractive color mixture method The toner can be obtained by electrostatically adhering the toner particles in the color liquid developer (1) to form a visible image and superimposing colors.
The liquid developer used in this method contains the pigments for cyan, magenta and yellow, respectively, together with a resin or fat such as rosin, linseed oil, soybean oil, modified alkyd resin, styrene-butadiene resin, acrylic resin or the like and aliphatic carbonization. It is obtained by pulverizing and dispersing in a carrier liquid having a high insulating property and a low dielectric constant such as hydrogen.

Further, in order to obtain a positively chargeable liquid developer, a charge control agent such as metal soap is added during or after dispersion to obtain a desired charge amount. It is believed that the mechanism of charging by a charge control agent such as metal soap is that the ions dissociated in the carrier liquid are adsorbed on the toner particles centering on the pigment. In such a mechanism, when the liquid developer is stored for a long period of time, or when the amount of charge changes with the change in the amount of adsorbed ions when running, the color superimposition balance of the toner particles of each color collapses, and the original image or A full-color image faithful to the image signal cannot be obtained. As a yellow pigment, an azo pigment in which an active methylene group is coupled with diazo is known, and a disazo pigment is usually used from the viewpoint of light resistance or solvent resistance. However, when these conventional yellow pigments are used, it is possible to obtain a stable liquid developer for electrostatography when a long-term storage or running is caused by fluctuations in charge amount due to dispersibility anxiety factors such as aggregation. Was difficult.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a positively chargeable yellow liquid developer suitable for color superposition type electrostatic photography.

[0005]

The first aspect of the present invention is to provide a yellow liquid developer for electrostatic photography in which a colorant and a toner containing a resin as a main component are dispersed in a carrier liquid. General formula (I)

[Chemical 1] (However, R ¹ and R ² each represent a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group.).

The second aspect of the present invention is a yellow liquid developer for electrostatic photography, which comprises a carrier liquid and a toner mainly containing a colorant and a resin dispersed therein. II)

[Chemical 2] (However, R ³ represents a lower alkyl group, R ⁴ represents a hydrogen atom, a lower alkyl group or a lower alkoxy group, and A represents —S.
-Or-NHCO- is shown. n is an integer of 6-12. ) Is used.

By the way, the inventors of the present invention have conducted researches to solve the above problems, and found that the problems can be solved by using a pigment having a specific structure as a colorant. The present invention has been completed. The present invention will be described in more detail below.

First, the description will be made starting from the pigment represented by the general formula (I). This pigment is insoluble in the carrier liquid, but by introducing polar groups called amide groups into both sides of the pigment molecular structure, the adsorption of ions dissociated from the charge control agent becomes stable, and the toner Does not change when stored for a long period of time or when running, and a stable liquid developer for electrostatic photography can be obtained.

The pigment represented by the general formula (I) can be produced by the method described below. The coupling component is produced by dissolving 3-amino-4-methoxybenzoic acid amide in acetone and reacting with diketene in the presence of a base such as pyridine. The diazo component is derived from the precursor aniline derivative by Saunders, KH (The Aromatic Di
Azocompounds and Their Technical Applications). The coupling reaction may be carried out by dissolving the coupling component in an alkaline aqueous solution, making it weakly acidic with acetic acid, gradually adding an aqueous solution of diazo for coupling, and heating the mixture for a while.

Typical examples of the pigment represented by the general formula (I) are as follows. (No. I-1)

[Chemical 5] (No. I-2)

[Chemical 6] (No. I-3)

[Chemical 7] (No. I-4)

[Chemical 8]

Next, the pigment represented by the general formula (II) will be described. This pigment is insoluble in the carrier liquid, but by introducing an alkyl group having an affinity for the carrier liquid and the resin into the pigment molecular structure, the dispersion stability was improved, and thus the toner was stored for a long time. In this case, the electrostatic charge does not fluctuate when running, and a stable liquid developer for electrostatic photography can be obtained.

The pigment represented by the general formula (II) can be produced by the method described below. The bis (acetoacetamino) alkane derivative, which is the coupling component, can be obtained by reacting an alkylenediamine derivative with twice the amount of diketene. As reaction conditions, the alkylenediamine derivative is dissolved or dispersed in an acetone solvent, and diketene is gradually added in the presence of a base such as pyridine to react. The precipitated crystals are recrystallized with a solvent such as alcohol. Diazo derivative is the precursor aniline derivative
Saunders, KH's book (The Aromatic Diazocompounds a
nd Their Technical Applications). In the coupling reaction, the bis (acetoacetamino) alkane derivative is dissolved in N, N-dimethylformamide and a small amount of acetic acid is added. Further, a diazo derivative may be added, an aqueous solution of sodium acetate may be added thereto for coupling, and heating may be performed when necessary.

Typical examples of the pigment represented by the general formula (II) are as follows. (No. II-1)

[Chemical 9] Among them, compounds of n = 10 (Specific Example No. II-1-1)
And the compound of n = 12 (Specific Example No. II-1-2) are preferable. (No. II-2)

[Chemical 10] Among them, the compound of n = 6 (Specific example No. II-2-1) and the compound of n = 12 (Specific example No. II-2-2) are preferable.

To prepare a liquid developer using these pigments of the present invention, 1 to 10 parts by weight of the pigment of the present invention and binder 1 are used.
˜50 parts by weight and 40 to 100 parts by weight of carrier liquid are kneaded and dispersed in an attritor, a ball mill, a sand mill or the like to obtain a concentrated toner, and if necessary, this may be diluted with the same carrier liquid. Further, in order to control the amount of charge to be preferable, a generally used charge control agent such as metal soap or metal naphthenate may be added as an additive during dispersion and / or dilution, if necessary. The many pigments may be used alone or in combination of two or more.

Here, as the binder, an alkyd resin,
A rosin-modified phenol-formaldehyde resin, a polyhydric alcohol ester of hydrogenated rosin, a polyacrylic or polymethacrylic ester resin, a styrene resin, a chlorinated rubber and the like are used, but especially an acrylic monomer for the styrene-butadiene copolymer shown below. It is effective to use the resin (I) obtained by polymerizing.

The resin (I) here is obtained by polymerizing at least one kind of styrene-butadiene resin or vinyltoluene-butadiene resin and at least one kind of monomer selected from the general formula (III) of the following chemical formula 11. It is a non-aqueous resin used.

Embedded image To actually produce this resin (I), a styrene-butadiene copolymer is used as a non-aqueous type. In the presence of a polymerization initiator such as azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO), which initiates the polymerization at a relatively low temperature, after being dissolved in a solvent, the monomer of the general formula (III) is added dropwise. The polymerization reaction may be carried out at a temperature of about 60 to 120 ° C.

The monomer represented by the above general formula (III) is a monomer which can be a solvated component even after polymerization, and specific examples thereof include lauryl methacrylate, lauryl acrylate, stearyl methacrylate, steryl acrylate and 2-ethylhexyl methacrylate. , 2-ethylhexyl acrylate, dodecyl methacrylate,
There are dodecyl acrylate, hexyl methacrylate, hexyl acrylate, octyl methacrylate, octyl acrylate, cetyl methacrylate, cetyl acrylate, vinyl laurate, vinyl stearate, nonyl methacrylate, nonyl acrylate, decyl methacrylate, decyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, and the like.

The above-mentioned AIB can be used as the polymerization initiator.
In addition to N and BPO, phenylazotriphenylmethane, lauroyl peroxide, t-butyl peroxide and the like can be mentioned.

Here, a production example of the resin (I) will be given. (Resin of Production Example I) Toluene 40 was added to a 2.0 liter flask equipped with a stirrer, a thermometer, a condenser and a dropping funnel.
0 g, styrene-butadiene resin (Pryolite S-
5) (manufactured by Goodyear Co., Ltd.) was charged, and a monomer solution consisting of 400 g of 2-ethylhexyl methacrylate and 10 g of benzoyl peroxide was added dropwise thereto over 2 hours while heating and stirring at 80 ° C. After that, polymerization was carried out at this temperature for 5 hours. As a result, a resin dispersion having a polymerization rate of 95% was obtained.

The carrier liquid used in the liquid developer of the present invention is preferably an aliphatic hydrocarbon or its derivative. Specific examples thereof include, for example, paraffinic or isoparaffinic hydrocarbons (Esso's Isopar H, Isopar G, Isopar L, Isopar K, etc.), ligroin, n-hexane, isooctane, cyclohexane, etc., alone or in combination. The above is used in combination.

[0021]

EXAMPLES Next, examples will be shown. The percentages here are by weight.

Example 1 Pigment of (No. I-1) 5 g Resin of Production Example 1 (as solid content) 10 g Zirconium naphthenate (metal content 4%) 0.25 g Isopar H (including solvent in resin) 84.75 g A mixture of these compositions was dispersed in a ball mill for 24 hours to obtain a concentrated toner, 50 g of which was diluted in Isopar H1L to prepare a yellow liquid developer for electrostatic photography, and the specific charge amount after 24 hours of dilution was calculated. Was measured and found to have a positive charge of 2120 μC / g. Subsequently, when this was subjected to negative latent image formation and development with an electrostatic color plotter CE-3436 (manufactured by Versatech), an image with high fog-free contrast was obtained. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but almost no precipitation was observed and the specific charge amount was 2070 μC / g, which was a good retention property. showed that. The results of measuring the specific charge of this product are summarized in Table 1.

Example 2 Instead of the pigment of (No. I-1), the pigment of (No. I-) was used.
A developer was prepared in the same manner as in Example 1 except that the pigment of 2) was used, and then printing was performed in the same manner. As a result, a high-contrast image without fog was obtained. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but almost no precipitation was observed. The results of measuring the specific charge of this product are summarized in Table 1.

Example 3 Instead of the pigment of (No. I-1), the pigment of (No. I-) was used.
A developer was prepared in the same manner as in Example 1 except that the pigment of 3) was used, and then printing was carried out in the same manner. As a result, a high-contrast image without fog was obtained. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but almost no precipitation was observed. The results of measuring the specific charge of this product are summarized in Table 1.

Comparative Example 1 A developer was prepared in the same manner except that Pigment Yellow 12 was used in place of the pigment used in Example 1 and subsequently printing was carried out in the same manner, and an image with a little fog was obtained. Was given. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but a large amount of precipitate was observed. In addition, the results of measuring the specific charge of this product are summarized in Table 1.

Comparative Example 2 A developer was prepared in the same manner except that Pigment Yellow 13 was used in place of the pigment used in Example 1 and printing was carried out in the same manner, and an image with a little fog was obtained. Was given. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but a large amount of precipitate was observed. In addition, the results of measuring the specific charge of this product are summarized in Table 1.

Example 4 Pigment of the above (No. II-1-1) 5 g Resin of Production Example 1 (as solid content) 10 g Zirconium naphthenate (4% metal content) 0.25 g Isopar H (also solvent in resin) 84.75 g A mixture of these compositions is dispersed in a ball mill for 24 hours to obtain a concentrated toner, 50 g of which is diluted in Isopar H1L to prepare a yellow liquid developer for electrostatic photography. When the charge amount was measured, it was positively charged and was 2310 μC / g. Subsequently, when this was subjected to negative latent image formation and development with an electrostatic color plotter CE-3436 (manufactured by Versatech), an image with high fog-free contrast was obtained. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but almost no precipitation was observed, and the specific charge amount was 2240 μC / g, which was a good retention property. showed that. The results of measuring the specific charge of this product are summarized in Table 1.

Example 5 Instead of the pigment of (No. II-1-1), the pigment of (No. II-II) was used.
A developer was prepared in the same manner as in Example 4 except that the pigment of II-1-2) was used, and then printing was carried out in the same manner. As a result, a high-contrast image without fog was obtained.
When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but almost no precipitation was observed. The results of measuring the specific charge of this product are summarized in Table 1.

Example 6 Instead of the pigment of (No. II-1-1), the pigment of (No. II-II) was used.
A developer was prepared in the same manner as in Example 4 except that the pigment of II-2-2) was used, and then printing was performed in the same manner. As a result, an image with high fog and high contrast was obtained.
When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but almost no precipitation was observed. The results of measuring the specific charge of this product are summarized in Table 1.

Comparative Example 3 A developer was prepared in the same manner except that Pigment Yellow 12 was used in place of the pigment used in Example 4, and printing was carried out in the same manner. An image with a little fog was obtained. Was given. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but a large amount of precipitate was observed. In addition, the results of measuring the specific charge of this product are summarized in Table 1.

Comparative Example 4 A developer was prepared in the same manner except that Pigment Yellow 13 was used in place of the pigment used in Example 4, and then printing was carried out in the same manner, whereby an image with a little fog was obtained. Was given. When this developer was stored at 50 ° C. for one month and returned to room temperature, the precipitation state of particles was observed, but a large amount of precipitate was observed. In addition, the results of measuring the specific charge of this product are summarized in Table 1.

[0032]

[Table 1]

[0033]

EFFECT OF THE INVENTION The liquid developer for electrostatic photography according to the present invention is extremely stable because the amount of charge hardly changes during long-term storage and running.

Front page continuation (72) Inventor Nobutaka Kinoshita 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A liquid developer for electrostatic photography, comprising a carrier liquid and a toner mainly composed of a colorant and a resin dispersed therein, wherein the colorant is a pigment represented by the following general formula (I). A yellow liquid developer for electrostatic photography, characterized in that. [Chemical 1] (However, R ¹ and R ² each represent a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group.) 2. A liquid developer for electrostatic photography, comprising a carrier liquid and a toner containing a colorant and a resin as main components, wherein the pigment is represented by the following general formula (II). A yellow liquid developer for electrostatic photography, characterized in that. [Chemical 2] (However, R ³ represents a lower alkyl group, R ⁴ represents a hydrogen atom, a lower alkyl group or a lower alkoxy group, and A represents —S.
-Or-NHCO- is shown. n is an integer of 6-12. ) 3. The yellow liquid developer for electrostatic photography according to claim 2, wherein the pigment represented by the general formula (II) is a compound represented by the following chemical formula 3 or chemical formula 3. [Chemical 3] [Chemical 4]