KR20030071320A - Method for manufacturing liquid composition for developing latent electrostatic images - Google Patents

Abstract

PURPOSE: A method for preparing a wet developer is provided, to improve the conductivity (pMho/cm) and the mass of the developed liquid toner per unit area (M/A) compared with the already-known wet developers and to lower the manufacturing cost. CONSTITUTION: The method comprises the steps of mixing a paraffin-based hydrocarbon having a volatilization ratio less than 1 and a flash point of 90 deg.C or more, an acid-treated thermoplastic resin having a glass transition temperature of 40 deg.C or more, a flash point below 110 deg.C and an acid value of 20-150, a pigment, a charge control agent and a dispersant simultaneously and milling them; and milling the mixture solution at 20-40 deg.C for 2-5 hours. Preferably the charge control agent is a metal salt having zirconium; the acid-treated thermoplastic resin is a styrene-acrylate copolymer or a methacrylate copolymer; and the dispersant is an acrylate copolymer or an amine-based compound.

Description

Method for manufacturing liquid composition for developing latent electrostatic images

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a wet developer, and more particularly, to a method for producing a wet developer which is environmentally friendly and inexpensive to manufacture by producing in a short time at a relatively low temperature of less than 100 ° C.

Currently, many printers used in office environment are laser printers that use latent lasers to create latent images on the photoconductor, and then transfer the toner to the latent image on the photoconductor using a potential difference, and transfer the toner to a paper to form an image. . Inkjet printers are also widely used, but they are suitable for personal printers, and in the office environment, laser printers, which are connected to multiple computers and perform a large capacity printer, will continue to expand in the future.

Laser printers mainly developed / sold so far are mainly black and white dry printers. It is known that there is a limit in image quality and environmental problems caused by dust or the like caused by the presence of the toner in a powdered state in a manner that causes the toner to move to the latent image on the photoconductor (OPC) in the air by causing a triboelectric charge. We have been researching the wet printer as a way to improve the environmental problems and image quality. Wet printers exist as a solution in which the toner is dispersed in a solvent rather than a powder state. When the toner moves to a latent image on the photoconductor (OPC), the solvent is used as a medium, and thus influences external factors (temperature / humidity, etc.) unlike air. Not only do not receive, but also can overcome the environmental problems such as dust generation, and the particle size limit of the toner is also significantly overcome compared to the dry type (6㎛ or more) has the advantage that can obtain excellent image quality.

The wet developer consists of about 80% carrier, 15% binder, 3% pigment, and other additives. When prepared using a commercially available thermoplastic resin as a binder, it is generally difficult to dissolve the thermoplastic resin in a paraffinic hydrocarbon solvent. Therefore, in the case of producing a wet developer by dissolving a thermoplastic resin, the resin is dissolved in a carrier using a co-solvent and then cooled again to precipitate a resin using a difference in solubility according to temperature, and to disperse and coat the pigment. This is used. The carrier is then replaced with a pure hydrocarbon solvent to remove the cosolvent, followed by charging with the addition of a charge control agent (CCA).

US Patent No. 58,76896 discloses a method of using toluene as a cosolvent in the manufacture of a developer, as shown in FIG. 1, but aromatic compounds such as toluene, which is used as a cosolvent, are known to be harmful to humans. Therefore, there is a disadvantage that the manufacturing method using the same is not environmentally friendly. In addition, US Patent No. US6108513, as shown in Figure 2 is a phenomenon of mixing the resin and the carrier at a high temperature of 150 ℃ or more without using a co-solvent, and then put a pigment and other additives, such as a milling process for more than one day Although the manufacturing method of the agent is disclosed, the method of mixing at a high temperature and undergoing long milling is complicated and has a disadvantage in that the manufacturing cost increases.

Therefore, the technical problem to be achieved by the present invention is to overcome the problems of the prior art to provide a method for producing a wet developer that is environmentally friendly, short manufacturing time and low manufacturing cost.

1 is a schematic diagram of a method for producing a developer according to the prior art.

Figure 2 is a schematic diagram of a manufacturing method of a developer according to another prior art.

3 is a schematic view of a method for producing a developer according to the present invention.

The present invention to achieve the above technical problem

(a) paraffinic hydrocarbons having a volatility of less than 1, a flash point of 90 ° C. or more, an acid-treated thermoplastic resin having a glass transition temperature of 40 ° C. or more, a softening point of less than 110 ° C., and an acid value of 20 to 150, a pigment, a charge control agent and a dispersant Simultaneously mixing and milling; And

(b) milling the mixed solution at 20 to 40 ° C. for 2 to 5 hours.

According to one embodiment of the present invention, the paraffinic hydrocarbon solvent is preferably any one selected from the group consisting of Isopar M, Isopar V, Norpar 13, Norpar 15.

In addition, the acid-treated thermoplastic resin is preferably a styrene-acrylate copolymer or methacrylate copolymer.

The wet developer according to claim 1, wherein the acid treated thermoplastic resin is a styrene-acrylate copolymer or a methacrylate copolymer.

According to another embodiment of the present invention, the pigment is preferably a mixture selected from the group consisting of sunfast magenta, sunfast blue, benzidine yellow, quinacridone, carbon black and perylene green.

In addition, the charge control agent is preferably a metal salt having zirconium.

According to another embodiment of the present invention, the dispersant is preferably an acrylate copolymer or an amine compound.

Hereinafter, the present invention will be described in more detail.

The liquid developer prepared by the present invention determines the color of the liquid toner, pigments having a significant influence on the electrical properties of the liquid toner, coating the pigments and having a significant influence on the electrical properties of the liquid toner, It serves as a dispersion medium of a resin and a liquid toner, which disperse the resin and pigment in a solvent, which determine the development and transfer characteristics of the dispersion state and printing, and has a non-conductive property electrically so that only toner particles dispersed in an electric field And a charge control agent to impart electrical properties to the carrier solvent and liquid toner that allow for the movement of.

Pigments sold by Cabot / Degussa / Clariant / Magruder can be used for each color.For each color, for example, yellow, Hansa brilliant (PY74, Clariant) and magenta are Permanent Rubine F6B ( PR184, Clariant, cyan is PB15: 4 (Sun Chemical), and finally black is monarch 120 (carbon black, cabot). The resin may be a carboxylic acid-treated thermoplastic resin, and examples thereof include styrene-acrylate copolymer Joncryl (manufactured by Johanson polymer), methacrylate copolymer elvicite (manufactured by Ineos), Paraloid (manufactured by Rohm & Haas), etc. There is this.

As the dispersant, an acrylate copolymer or an amine compound is used. Examples of the acrylate copolymer are Disperbyk 116 (manufactured by BYK chemie) and the amine compound is a solsperse series (manufactured by Avecia). As the charge control agent, a metal salt having zirconium can be used, for example, zirconium octoate, zirconium hexem, zirconium naphthenate and the like. In the present invention, milling was performed using a Torus mill / attrition mill (manufactured by Getzmann).

Milling produced a wet developer using a Torus mill / attrition mill (manufactured by Getzmann).

In the case of the wet developer consisting of the above components, the (+) charging property is excellent, and in particular, the milling process takes a very short time, so the manufacturing process is simple.

As shown in FIG. 3, when a combination of a paraffinic hydrocarbon having a volatility of 1 or less and a flash point of 90 ° C. or more and a carboxylic acid-treated thermoplastic resin having an acid value of 20 to 150 is used, a short time of about 4 hours in total Wet developer can be prepared. Since the pigment, the charge control agent and the dispersant are mixed and milled in the mixed solution at the same time, the reaction process is very shortened and the manufacturing cost becomes low. On the other hand, it is preferable that the mass ratio of resin and a pigment is 1: 4-1: 8, and the mass ratio of resin and a dispersing agent is 1: 2-1: 10.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited thereto.

Example 1

As a carrier, 2.5 g of Joncryl (manufactured by Johnson polymer) was mixed as a thermoplastic resin treated with Isopar M, and Hansa brillant (PY74, manufactured by Clariant), permanent rubin F6B (PR184, manufactured by Clariant), PB15: 4 (manufactured by Sun chemican) and monarch 120 (carbon black, manufactured by Cabot) were used as pigments. Next, 0.25 g of solsperse 13940 (manufactured by Avecia) was mixed as a dispersant, and zirconium octoate was charged together as a charge control agent in the vessel, and then milled at 3000 rpm using Dispermat (VMA GETZMANN) for 1.5 hours at a temperature of less than 100 ° C. . Subsequently, the mixture was stirred and cooled at room temperature for 2 hours to obtain toner particles having a volume average size of 3-4 μm. Next, glass beads were filtered through the filtering process of the toner particle dispersion solution obtained above to obtain a wet developer.

Example 2

A wet developer was prepared in the same manner as in Example 1, except that elvacite (manufactured by Ineos, Inc.) was used as the resin.

Example 3

A wet developer was prepared in the same manner as in Example 1, except that Paraloid (manufactured by Rohm & Hass) was used as the resin.

Experimental Example

The properties of the wet developer prepared in Example 1-3 were measured and shown in Table 1 below.

Wet developer Example 1 Example 2 Example 3 Remarks Post-Mass Mass / Area 238 223 230 Optimum range: 200 to 250 Conductivity (pMho / cm) 16.7 19 21 Optimum range: 10-30

As can be seen from the above results, the wet developer produced by the present invention is excellent.

As described above, the manufacturing method of the wet developer according to the present invention has a manufacturing time of about 4 hours and is easy to manufacture, and the manufacturing cost is greatly reduced. In addition, the wet developer prepared by the above method is environmentally friendly using a low volatility solvent, and has excellent conductivity (pMho / cm) and mass (M / A) of the developed liquid toner per unit area.

Claims (6)

(a) paraffinic hydrocarbons having a volatility of less than 1, a flash point of 90 ° C. or more, an acid-treated thermoplastic resin having a glass transition temperature of 40 ° C. or more, a softening point of less than 110 ° C., and an acid value of 20 to 150, a pigment, a charge control agent and a dispersant Simultaneously mixing and milling; And (b) milling the mixed solution at 20 to 40 ° C. for 2 to 5 hours. The wet developer according to claim 1, wherein the paraffinic hydrocarbon solvent is any one selected from the group consisting of Isopar M, Isopar V, Norpar 13, and Norpar 15. The wet developer according to claim 1, wherein the acid treated thermoplastic resin is a styrene-acrylate copolymer or a methacrylate copolymer. The wet developer according to claim 1, wherein the pigment is a mixture selected from the group consisting of sunfast magenta, sunfast blue, benzidine yellow, quinacridone, carbon black and perylene green. 2. The method of claim 1, wherein the charge control agent is a metal salt having zirconium. The wet developer according to claim 1, wherein the dispersant is an acrylate copolymer or an amine compound.