Carbon black

[Industrial Application Field] The present invention relates to carbon black. The specific carbon black of the present invention has a significantly improved blackness, and such carbon black is suitably used for pigments such as paints, inks, and resins.

[0002] Carbon black is a black pigment having the smallest particle size among industrially produced pigments, and has extremely high coating power and coloring power. Therefore, paints, inks, and resins. It is used as a coloring pigment for coloring and the like. The degree of blackness is mainly determined by the particle size, and the improvement has been achieved by reducing the particle size and increasing the specific surface area. As the particle size becomes smaller, there is a problem that dispersion becomes more difficult. Therefore, we have dealt with it by optimizing the amount of surface volatile matter (surface oxygen-containing functional group), but it has not been sufficient yet.

[0003] Carbon black is broadly classified into channel black and furnace black in terms of manufacturing method. Channel black, which is a representative of carbon black with a small particle size, high specific surface area, and high surface volatile capacity, was initially manufactured by utilizing natural gas, which was a by-product of crude oil production. There are various manufacturing problems such as air pollution in the manufacturing area, shortage of raw material (natural gas) supply and conversion to consumer use, soaring raw material costs, and low yield, and they are about to disappear. In particular, in carbon black for high-grade colors having a small particle size and a high specific surface area, furnace black has a smaller amount of surface volatile content than channel black, and is used after being appropriately post-treated. Among the post-treatments, the oxidation state of the oxidation treatment was not sufficient as compared with that of channel black.

[0004] [Problems to be Solved by the Invention] However, the conventional carbon black is not sufficiently dispersed in all cases, and an industrially wide-ranging carbon black having good dispersion is required. .. As a result of diligent studies to solve the above problems, the present inventor has found that carbon black having specific physical properties significantly improves the blackness, and has arrived at the present invention.

[Means for Solving the Problems] That is, the present invention has an infrared absorption spectrum (absorption display) of 1805 cm.^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1It exists in carbon black, which is characterized in that the ratio of the maximum absorption value of is 0.65 or more.

[0006] Further, the present invention has an infrared absorption spectrum (absorption display) of 1805 cm.^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1It exists in furnace black, which is characterized in that the ratio of the maximum absorption value of is 0.5 or more.

[0007] Hereinafter, the present invention will be described in detail. The carbon black of the present invention has an infrared absorption spectrum (absorbance display) of 1805 cm.^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1The feature is that the ratio of the maximum absorption value of is 0.5 or more.

[0008] The measurement of the infrared absorption spectrum is performed by, for example, Fourier Transform Infrared Spectroscopy (FT-IR) and the transmission method of KBr tablets. In the obtained infrared absorption spectrum (absorption display), 1805 cm^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1Find the ratio of the maximum absorption values of.

[0009] 1800 ~ 1670 cm^-1The absorption peak of is due to the carboxyl group (1720 cm)^-1) Exists, 1670 ~ 1500cm^-1Absorption peak is C = O (1650 ~ 1630cm)^-1), COO^-(1560 ~ 1590cm^-1) Although there is a cause, the spectral shape is affected by the surface condition of carbon black. Even in the presence of such a carboxyl group, 1805 cm^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1If the ratio of the maximum absorption value of is 0.65 or more, especially 0.65 to 2.0, especially 0.65 to 1.5, the blackness can be significantly increased.

[0010] Therefore, if the intensity ratio is set to 0.65 or more by surface treatment, the blackness can be remarkably improved as compared with carbon black having the same particle size and the same surface area. As a raw material for obtaining the specific carbon black of the present invention, either furnace black or channel black can be used, but furnace black is more preferable in terms of environmental problems and manufacturing problems.

[0011] Commercially available channel blacks are oxidized, but the degree of oxidation is not at a sufficient level, and in the present invention, including those having such a low degree of oxidation, infrared absorption is absorbed. 1805 cm in spectrum (absorption display)^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1The ratio of the maximum absorption value of is less than 0.65 is used.

[0012] Some of the commercially available furnace blacks are slightly oxidized, but in the infrared absorption spectrum (absorption display), 1805 cm.^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1The ratio of the maximum absorption value of is less than 0.5 is used.

[0013] As a surface treatment method for carbon black, 1805 cm in the infrared absorption spectrum (absorption display).^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1The ratio of the maximum absorption value of is not particularly limited as long as it can be obtained at 0.65 or more, and examples thereof include air oxidation at high temperature, ozone oxidation, catalytic oxidation, nitric acid oxidation, low temperature plasma oxidation, and addition of organic acid. Ozonolysis is preferable in consideration of the degree of oxidation, manufacturing cost, handling, and the like.

[0014] Regarding the ozone oxidation conditions, the ozone concentration is 0.01 to 50 g / m.³The processing time is 10 seconds to 200 hours, and the pressure may be pressurized or depressurized, but it is preferable to use normal pressure for economic and safety reasons. Regardless of the type of reaction vessel, fixed bed or fluidized bed, the temperature shall be controlled to the extent that a dust explosion does not occur.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

[Example 1] Furness Black (particle size 13 nm S BET 360 m)²/ g) 10 g was placed in a glass rotating kiln, and an air-containing gas with an ozone gas generation amount of 0.2 g / h was flowed at 0.6 liter / min and treated for 100 hours. The infrared absorption spectrum of this ozone-oxidized carbon black was measured by Fourier transform infrared spectroscopy (FT-IR "Nikolai system 550") by the transmission method of KBr tablets. MCT is used for the detector, and the resolution is 4 cm.^-1, The measurement was performed with 256 scans. The equipment to be used was sufficiently dried in advance, and first, KBr-only tablets were prepared. KBr crystals are crushed in an agate mortar, 0.1 g of which is vacuum degassed in a tablet molder (10 mmφ manufactured by Nippon Kogaku Co., Ltd.) for 5 minutes, and then evacuated to 500 kg / cm with a hydraulic press.²KBr tablets were prepared by pressure molding for 1 minute. The obtained tablets were set in the sample chamber of FT-IR, subjected to nitrogen purging for 1 hour, and then the spectrum was measured and used as the background. Next, carbon black was dried at 115 ° C. for 1 h, and then carbon black and KBr were mixed at a ratio of 1: 7000 in an agate mortar, and 0.1 g was prepared as tablets in the same manner as above. This was set in the sample chamber of FT-IR, nitrogen purged for 15 to 30 minutes, and the spectrum was measured. In the obtained infrared absorption spectrum (absorption display), 1805 cm as shown in Fig. 1.^-1And 900 cm^-11670 ~ 1500cm with the straight line connecting the absolutes in^-11800 ~ 1670cm for the maximum absorption value in^-1The ratio of the maximum absorption value of was 0.78.

[0017] In a 140 ml glass bottle, this carbon black 2.12 g, varnish (Dai Nippon Toryo Co., Ltd. "Acroze # 6000") 14.88 g, thinner (Dainippon Toryo Co., Ltd. "Acroze # 6000") 10 g, glass beads (2.5 to 3.5 mmφ) ) 90 g was added and dispersed with a paint conditioner for 90 minutes, and then 57.8 g of varnish was added and dispersed with a paint conditioner for 30 minutes to prepare a paint. The paint was put in a round glass cell and solidified, and the L value was measured with a spectroscopic color difference meter (Nippon Denki "SZ-Σ90" 0 ° illumination-45 ° light reception) and found to be 3.87.

[Comparative Example 1] Mitsubishi Kasei "# 2650" (Furness Black particle size 13 nm S BET 360 m²The infrared absorption spectrum (Fig. 2) was measured in the same manner as in Example 1 except that / g) was used. The peak height ratio was 0.25. The L value of the acrylic resin paint was 5.19.

[Comparative Example 2] As a commercially available channel black, "FW200" manufactured by Degussa (particle size 11 nmS BET 580 m)²The infrared absorption spectrum (Fig. 3) was measured in the same manner as in Example 1 except that / g) was used. The peak height ratio was 0.58. The L value of the acrylic resin paint was 4.58.

[Comparative Example 3] As a commercially available furnace black, Cabot's "Monarch" 1300 (particle size 11 nm S BET 540 m)²The infrared absorption spectrum (Fig. 4) was measured in the same manner as in Example 1 except that / g) was used. The peak height ratio was 0.25.

[Effect of the Invention] The carbon black of the present invention can remarkably improve the blackness of paints, inks, resins and the like, and provides a great industrial benefit.

BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] Infrared absorption spectrum obtained in Example 1.

FIG. 2 is an infrared absorption spectrum obtained in Comparative Example 1.

FIG. 3 is an infrared absorption spectrum obtained in Comparative Example 2.

FIG. 4 is an infrared absorption spectrum obtained in Comparative Example 3.