JP2901013B2 - Yellow liquid developer for electrostatic photography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a process in which toner particles are electrostatically attached to an electrostatic latent image formed on an electrophotographic photosensitive member or an electrostatic recording member to form a visible image and color overlap. The present invention relates to a positively chargeable yellow liquid developer for electrostatography which is used.

(Prior art) In order to obtain a full-color image by electrophotography or electrostatic recording, an electrostatic latent image is formed on an electrophotographic photoreceptor or electrostatic recording paper by a conventional method, and a primary color color liquid is developed according to a subtractive color mixing method. It is obtained by electrostatically attaching toner particles in the agent to form a visible image and superimposing colors.

The liquid developer used in this method is composed of a resin such as rosin, linseed oil, soybean oil, modified alkyd resin, styrene butadiene resin, acrylic resin, or a fat or oil together with a high insulating and low dielectric substance such as an aliphatic hydrocarbon. And obtained by grinding and dispersing in a carrier liquid at a predetermined rate.

Further, in order to obtain a positively chargeable liquid developer, a desired charge amount is obtained by adding a charge control agent such as metal soap during or after dispersion. It is considered that the mechanism of charging of the metal soap by the charge control agent is that ions dissociated in the carrier liquid are adsorbed on the toner particles, mainly the pigment. In such a mechanism, when the liquid developer is stored for a long period of time or when copying is continued, the charge amount tends to fluctuate due to a change in the amount of adsorbed ions, and it is difficult to obtain a stable liquid developer. Met.

(Object) It is an object of the present invention to provide a positively chargeable yellow liquid developer suitable for color superposition type electrophotography, which eliminates the above-mentioned disadvantages.

(Structure) In order to solve the above-mentioned problems, studies have been made in the past, but it has been found that the problem can be solved by modifying the surface of a pigment having a specific structure with an aliphatic amine. That is, the present invention relates to a color for electrophotography, wherein the pigment is represented by the following general formula (I) in a liquid developer obtained by dispersing toner particles mainly containing a pigment and a resin in a carrier liquid. It consists of a liquid developer.

The pigment represented by the general formula (I) is, for example, a pigment represented by the general formula (II)
And a carbonyl group and an aliphatic amine of an acetoacetic acid arylamide-based insoluble disazo pigment as shown in Table 1.
It is obtained by performing a heating dehydration reaction at 70 to 200 ° C. The reaction can be performed in an organic solvent or an aqueous medium.

Depending on the amine used and its amount, especially the ratio of the acetoacetic acid arylamide-based insoluble disazo pigment, a pigment in which all or only a part of the carbonyl groups have reacted with the amine is obtained, whereby the desired charge is obtained when the liquid developer is used. You can control the quantity.

Further, the liquid developer using the pigment according to the invention has excellent dispersion stability in a simple liquid. This is because the affinity of the long-chain alkyl group to the carrier liquid is high due to the effect expected when the alkyl group of the aliphatic amine has 6 to 20 carbon atoms.

The aliphatic amine used in the present invention is, for example, stearylamine, oleylamine, cyclohexylamine, 3
-Dimethylaminopropylamine, 3-octadecylaminopropylamine and the like.

 Next, production examples of the pigment of the present invention will be described.

Pigment Production Example 1 50 parts of 3-octadecylaminopropylamine is dissolved in 50 parts of ethanol by heating, added to 1000 parts of an aqueous CI Pigment Yellow 12 slurry (50% solids), stirred at 80 ° C. for 1 hour, and then cooled. . The slurry was filtered to form a press cake, and then washed repeatedly with water, and dried and pulverized to obtain a powder pigment.

Pigment Production Example 2 3-Octadecylaminopropylamine in a mixer
Heat 30 parts to a temperature of 80 ° C and gradually add 70 parts of CI Pigment Yellow 12 (dry powder) to raise the temperature to 150 ° C.
Continue stirring for a time to obtain a yellow plastic. This material was cooled and pulverized to obtain a powder pigment.

Pigment Production Example 3 A powder pigment was obtained in the same manner as in Pigment Production Example 1 except that 3-octadecylaminopropylamine was changed to stearylamine.

Pigment Production Example 4 A powder pigment was obtained in the same manner as in Pigment Production Example 2, except that CI Pigment Yellow 12 was changed to CI Pigment Yellow 13.

Pigment Production Example 5 A powder pigment was obtained in the same manner as in Pigment Production Example 1, except that 100 parts of ethanol and 100 parts of 3-octadecylaminopropylamine were used.

Next, examples of the binder resin that can be used in the liquid developer of the present invention include those described in the section of the prior art, but a bradiene-acryl copolymer is more preferable. The butadiene-acrylic copolymer (hereinafter referred to as resin (A)) is obtained by polymerizing at least one kind of styrene-butadiene resin or vinyltoluene-butadiene resin with at least one kind of monomer selected from the following general formula (III). Non-aqueous resin obtained by

In order to produce the resin (A), a styrene-butadiene copolymer is dissolved in a non-aqueous solvent, and then a monomer of the general formula (III) is added dropwise, and azobisisobutyronitrile (AIBN),
The polymerization reaction may be performed at a temperature of about 60 to 120 ° C. in the presence of a polymerization initiator such as benzoyl peroxide (BPO) that initiates polymerization at a relatively low temperature.

The monomer represented by the general formula (III) is a monomer that can be a solvation component even after polymerization, and specific examples thereof include lauryl methacrylate, lauryl acrylate,
Stearyl methacrylate, stearyl acrylate,
2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, dodecyl methacrylate, 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.

As the polymerization initiator used in the present invention, the above-mentioned AIB
In addition to N and BPO, phenylazotriphenylmethane, lauryl peroxide, t-butyl peroxide and the like can be mentioned.

 Here, a production example of the resin (A) will be described.

Production Example of Resin (A) Equipped with stirrer, thermometer, cooling pipe, and dropping funnel
A 20-liter flask was charged with 400 g of toluene and 300 g of styrene-butadiene resin (Priolite S-5, manufactured by Goodyear), and heated and stirred at 80 ° C., into which 400 g of 2-ethylhexyl methacrylate and benzoyl peroxide were added.
A 10 g monomer solution was added dropwise over 2 hours. Thereafter, polymerization was carried out at this temperature for 5 hours. As a result, a resin dispersion having a polymerization rate of 95% was obtained.

As the carrier liquid used in the liquid developer of the present invention, an aliphatic hydrocarbon or a derivative thereof is preferable.

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 of two or more. Are used in combination.

In order to obtain a yellow liquid developer for electrostatography using the above-described materials, 1 to 5 parts by weight of resin (A) (as resin solid content) and carrier liquid are added to 1 part by weight of the pigment of the present invention. Ten~
30 parts by weight may be kneaded and dispersed by an attritor, a ball mill, a sand mill, or the like to obtain a concentrated toner, which may be diluted with a similar carrier liquid as necessary. Since the pigment of the present invention has a very high dispersibility in a carrier liquid due to the introduction of a long-chain alkyl group, a stable concentrated toner can be obtained without using a disperser.

 Next, a specific example will be described.

Example 1 Pigment of Production Example 1 5 parts Resin (A) (solid content conversion) 10 parts Isopar H (including solvent in resin (A)) 85 parts Mixtures of the above compositions were dispersed in a ball mill for 24 hours. As a concentrated toner, 50 g of the toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatography, and the specific charge of the toner 24 hours after the dilution was measured. there were. Subsequently, when a negative latent image was formed with an electrostatic color plotter CE-3436 (manufactured by Versatech) and development was performed, an image with no fog and a high contrast was obtained. After storing this developer at 50 ° C. for one month, it was returned to normal temperature and the sedimentation state of the particles was hardly observed, and the specific charge was measured.
470 μC / g, indicating good storage characteristics.

In addition, the measurement result of the specific charge amount is shown in Table 2 together with the following Examples and Comparative Examples.

Example 2 Pigment of Production Example 2 5 parts Resin (A) (in terms of solid content) 10 parts Isopar H (including solvent in resin (A)) 85 parts Mixtures of the above compositions were dispersed in a ball mill for 24 hours. As a concentrated toner, 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. The obtained liquid developer shows a positive charge property, and forms a latent image with an electrostatic color plotter CE-3436 (manufactured by Versatech).
After development, a high-contrast image without fog was obtained. After storing this developer in the same manner as in Example 1, the temperature was returned to room temperature and the sedimentation state of the particles was observed.

Example 3 Pigment of Production Example 3 5 parts Resin (A) (in terms of solid content) 10 parts Isopar H (including the solvent in resin (A)) 85 parts Mixtures of the above compositions were dispersed in a ball mill for 24 hours. As a concentrated toner, 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. The obtained liquid developer showed a positive charge property, and when this was used to form a latent image with an electrostatic color plotter CE-3436 (manufactured by Versatech) and developed, a high-contrast image without fog was obtained. .

Example 4 Pigment of Production Example 5 5 parts Resin (A) (in terms of solid content) 10 parts Isopar H (including the solvent component in resin (A)) 85 parts Mixtures of the above compositions were dispersed in a ball mill for 24 hours, respectively. As a concentrated toner, 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. The obtained liquid developer showed a positive charge property, and when this was used to form a latent image with an electrostatic color plotter CE-3436 (manufactured by Versatech) and developed, a high-contrast image without fog was obtained. .

Example 5 Pigment of Production Example 5 5 parts Resin (A) (in terms of solid content) 10 parts Isopar H (including solvent in resin (A)) 85 parts Mixtures of the above compositions were dispersed in a ball mill for 24 hours. As a concentrated toner, 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. The obtained liquid developer showed a positive charge property, and when this was used to form a latent image with an electrostatic color plotter CE-3436 (manufactured by Versatech) and developed, a high-contrast image without fog was obtained. .

Comparative Example 1 Pigment Yellow 12 (untreated) 5 parts Resin (A) (in terms of solid content) 10 parts Isopar H (including solvent in resin (A)) 85 parts Mixtures of the above compositions were each dispersed in a ball mill for 24 hours. Then, 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. Although the obtained liquid developer was positively charged, it was developed with a latent image formed using an electrostatic color plotter CE-3436 (manufactured by Versatech), and an image with a little fog was obtained. Can be After storing the developer in the same manner as in Example 1, the temperature was returned to room temperature and the sedimentation state of the particles was observed. As a result, a large amount of sediment was observed.

Comparative Example 2 Pigment Yellow 13 (untreated) 5 parts Resin (A) (in terms of solid content) 10 parts Isopar H (including the solvent in resin (A)) 85 parts Mixtures of the above compositions were each subjected to ball milling for 24 hours. 50 g of the concentrated toner was dispersed and diluted in Isopar H1 to prepare a yellow liquid developer for electrostatography. Although the obtained liquid developer is positively charged, when the latent image is formed and developed with an electrostatic color plotter CE-3436 (manufactured by Versatech), an image with a little fogging is obtained. Obtained. After storing the developer in the same manner as in Example 1, the temperature was returned to room temperature and the sedimentation state of the particles was observed. As a result, a large amount of sediment was observed.

Comparative Example 3 Pigment Yellow 12 (untreated) 5 parts Resin (A) (in terms of solid content) 10 parts Zirconium naphthenate (metal content 4%) 0.25 parts Isopar H (including solvent in resin (A)) 85 Part The mixture having the above composition was dispersed in a ball mill for 24 hours to obtain a concentrated toner, and 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. The obtained liquid developer was positively charged. When a latent image was formed on the liquid developer using an electrostatic color plotter CE-3436 (manufactured by Versatech) and development was performed, an image with high contrast without fog was obtained. Was done. After storing this developer in the same manner as in Example 1, the temperature was returned to room temperature, and a latent image was formed and developed again. When the sedimentation state of the particles was observed, sedimentation was observed.

Comparative Example 4 Pigment Yellow 13 (untreated) 5 parts Resin (A) (in terms of solid content) 10 parts Zirconium naphthenate (metal content 4%) 0.25 parts Isopar H (including solvent in resin (A)) 85 Part The mixture having the above composition was dispersed in a ball mill for 24 hours to obtain a concentrated toner, and 50 g of the concentrated toner was diluted in Isopar H1 to prepare a yellow liquid developer for electrostatic photography. The obtained liquid developer is positively charged. When a latent image is formed on the liquid developer using an electrostatic color plotter CE-3436 (manufactured by Versatech) and development is performed, an image with high contrast without fogging is obtained. Obtained. After storing this developer in the same manner as in Example 1, the temperature was returned to room temperature, and a latent image was formed and developed again. Also,
When the sedimentation state of the particles was observed, precipitation was observed.

(Effect) The yellow liquid developer for electrostatography according to the constitution of the present invention shows a clear positive charge as apparent from the comparison between the example and the comparative example, and its electric characteristics change even after storage for a long time. It is less than a liquid developer and has excellent dispersion stability.

Claims (1)

(57) [Claims] 1. A liquid developer comprising toner particles containing a pigment and a resin as main components dispersed in a carrier liquid, wherein the pigment is represented by the following general formula (I): Yellow liquid developer