KR100467675B1 - Carbon black colloidal solution and preparation method thereof - Google Patents

Abstract

The present invention relates to a carbon black colloidal solution and a method for producing the same, the method for producing a carbon black colloidal solution of the present invention comprises the steps of: a) mixing the carbon black, surfactant and dispersion medium; b) adjusting the pH of the mixture to 7 or less; And c) pulverizing the resultant. According to the present invention, the fine dispersoid particles can be stably dispersed by adjusting the pH of the carbon black colloidal solution to 7 or less, preferably 3 to 4. Such a colloidal solution of carbon black fine particles having good dispersibility can be usefully used as a coating liquid for coating the surface of the water pipe, especially for improving the contrast of an image display device.

Description

Carbon black colloidal solution and preparation method thereof

The present invention relates to a carbon black colloidal solution, and more particularly, to a carbon black colloidal solution having excellent dispersion stability and a method of manufacturing the same.

Carbon black is black natural powder obtained by incomplete combustion of natural gas acetylene, anthracene, naphthalene, coal tar or aromatic petroleum residue. Specific gravity is 1.8 ~ 2.1, average particle size is 1 ~ 500㎛ and carbon content is about 95% or more. to be.

Carbon black is mainly used as a reinforcing agent of natural or synthetic rubber, printing toner, coloring pigment, conductivity enhancing agent and the like. In particular, it may be coated on the surface of the water pipe in order to improve the contrast of the image display device.

In this case, the hydrophobic carbon black is dispersed in a dispersion medium such as water and / or alcohol to prepare a colloidal solution, which is then coated on the surface of the water tube.

Normally, a carbon black colloidal solution is obtained by adding carbon black and a surfactant to a dispersion medium such as water and then separating the carbon black powder into fine particles by grinding. The stability of the colloidal solution is evaluated differently depending on the average particle diameter of the carbon black particles as the dispersoid, the application of the colloidal solution, and the like. The use of the coating liquid to be applied to the surface of the water pipe does not exceed 200 nm. It is preferable not to.

The present invention is to provide a carbon black colloidal solution having excellent dispersion stability.

Another technical problem to be achieved by the present invention is to provide a method for producing a carbon black colloid solution having excellent dispersion stability.

The technical problem of the present invention is to provide a carbon black colloidal solution comprising a carbon black colloidal solution comprising a carbon black, a surfactant and a dispersion medium, wherein the average particle diameter of the carbon black is 10 to 200 nm and the pH of the solution is 7 or less. will be.

The pH of the carbon black colloidal solution according to the present invention is 7 or less, more preferably 3 to 4, and the carbon black content is 0.1 to 30% by weight based on the total weight of the colloidal solution. The dispersion medium need not be particularly limited, but pure water, alcohol, or the like may be preferably used.

In addition, examples of the surfactant include sodium polycarbonate, ammonium polycarbonate, sodium naphthalene sulfonate or polyvinylpyrrolidone.

The carbon black colloidal solution according to the present invention is particularly useful as an induction for black coating the surface of the water pipe to improve the contrast of the image display device.

In this case, the addition amount of the surfactant should be controlled within a range that does not impair the conductivity, for example, preferably not more than 0.1% by weight based on the total amount of carbon black.

Technical problem of the present invention, a) mixing the carbon black, surfactant and dispersion medium; b) adjusting the pH of the mixture to 7 or less; And c) it may be made by the method of producing a carbon black colloidal solution, characterized in that it comprises the step of grinding the result.

In the method for preparing a carbon black colloidal solution according to the present invention, as the surfactant, polycarbonate, ammonium polycarbonate, naphthalenesulfonsoda or polyvinylpyrrolidone may be used as described above, and the pH may be added to the mixture. It can be adjusted by adding a suitable acid, although the type of acid is not particularly limited, but nitric acid or acetic acid may be preferably used.

Hereinafter, a method of preparing a carbon black colloidal solution according to the present invention will be described.

Carbon black powder and surfactant are added to a dispersion medium such as pure water or alcohol, mixed, and then ground to obtain a carbon black colloidal solution. In the carbon black colloidal solution thus obtained, the carbon black powder is separated into fine particles, and the hydrophobic portion of the surfactant is adsorbed on the surface of each fine particle.

However, the mixture of the carbon black powder, the surfactant, and the dispersion medium shows different pH values according to the number of -COOH and -OH groups appearing on the surface of the mixture depending on the type of carbon black used as the dispersant. When the colloid is poor in dispersibility and the colloid is in an acidic region with a pH value of 7 or less, more preferably, the dispersion stability is excellent when the pH value is 3 to 4, and when the pH value is lower than the above range, carbon black This is because, as the number of -OH groups or -COOH groups on the surface increases, the number of sites capable of bonding with the surfactant increases, thereby improving dispersion stability.

Therefore, if the pH of the mixture is adjusted to 7 or less by adding an acid such as nitric acid or acetic acid to the mixture of the carbon black powder, the surfactant, and the dispersion medium before the grinding process, even if the particle size of the carbon black, which is the dispersoid, becomes smaller than usual, For example, even when it is about 200 nm or less, a colloidal solution excellent in dispersion stability can be obtained.

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

Example 1

To 100 g of pure water, 10 g of carbon black (MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) and 0.5 g of naphthalene sulfone soda (PW40) were added and mixed, and then an appropriate amount of nitric acid was added to adjust the pH to 3.5. This mixture was then milled with a mill to produce a carbon black colloidal solution.

The pH of the prepared colloidal solution and the particle diameter of the dispersed carbon black were measured by a pH meter of Metrohm, Switzerland and Zetamester, Malvern, respectively, and dispersed by laser beam scattering. To evaluate the results are shown in Table 1 below.

Example 2

To 100 g of pure water, 10 g of carbon black (750B, Mitsubishi Chemical Co., Ltd.) and 0.5 g of naphthalenesulfone soda (PW40) were added and mixed, and then an appropriate amount of nitric acid was added to adjust the pH to 2.8. This mixture was then milled with a mill to produce a carbon black colloidal solution.

The pH of the prepared colloidal solution, the particle diameter of the dispersed carbon black, and the dispersed state were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1 below.

Comparative Example 1

To 100 g of pure water, 10 g of carbon black (750B, Mitsubishi Chemical Co., Ltd.) and 0.5 g of naphthalene sulfone soda (PW40) were added and mixed, and then an appropriate amount of nitric acid was added to adjust the pH to 8. The mixture was ground with a grinder to prepare a carbon black colloidal solution.

The pH of the prepared colloidal solution, the particle diameter of the dispersed carbon black, and the dispersed state were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1 below.

Comparative Example 2

To 100 g of pure water, 10 g of carbon black (4000B, manufactured by Mitsubishi Chemical Co., Ltd.) and 0.5 g of naphthalene sulfone soda (PW40) were added and mixed, and then an appropriate amount of nitric acid was added to adjust the pH to 10. This mixture was then milled with a mill to produce a carbon black colloidal solution.

The pH of the prepared colloidal solution, the particle diameter of the dispersed carbon black, and the dispersed state were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1 below.

As can be seen from the results in Table 1, in the case of the carbon black colloidal solution (Examples 1 and 2) according to the present invention, the particles of the dispersoid are finely reduced by adding an appropriate acid to adjust the pH to an acid range of 7 or less. Even if it is a good dispersion state can be maintained.

On the other hand, when the pH of the colloidal solution becomes more alkaline than 7 (Comparative Examples 1 and 2), not only the size of the dispersoid particles is large, but also the dispersion stability is poor, resulting in coherent dispersion or phase separation.

According to the present invention, fine dispersoid particles can be stably dispersed by adjusting the pH of the carbon black colloidal solution to 7 or less, preferably 3 to 4. Such a colloidal solution of carbon black fine particles having good dispersibility can be usefully used as a coating liquid for coating the surface of the water pipe, especially for improving the contrast of an image display device.

Claims (8)

In a carbon black colloidal solution containing carbon black, a surfactant and a dispersion medium, A carbon black colloidal solution, characterized in that the average particle diameter of the carbon black is 10-200 nm and the pH of the solution is 7 or less. The carbon black colloidal solution according to claim 1, wherein the pH is 3-4. The carbon black colloidal solution according to claim 1, wherein the carbon black content is 0.1 to 30% by weight based on the total weight of the colloidal solution. The method of claim 1, wherein the surfactant is selected from sodium polycarbonate, ammonium polycarbonate, sodium naphthalene sulfonate or polyvinylpyrrolidone Carbon Black Colloidal Solution. a) mixing the carbon black, the surfactant and the dispersion medium; b) adjusting the pH of the mixture to 7 or less; And c) a method of producing a carbon black colloidal solution comprising the step of pulverizing the resultant. The method of claim 5, wherein the surfactant is selected from sodium polycarbonate, ammonium polycarbonate, sodium naphthalene sulfonate or polyvinylpyrrolidone. Method for producing a carbon black colloidal solution. The method of claim 5, wherein the pH of the solution is adjusted to 3 to 4 in the step b). 8. The method of claim 5 or 7, wherein step b) is carried out by adding an acid to the mixture.