MXPA99004827A - Black of post-treated smoke oxidativame - Google Patents

Abstract

The present invention relates to an oxidatively post-treated carbon black. It is characterized in that its content of volatile constituent parts is greater than 10% in reference to its total weight, and the proportion of its CTAB surface to the iodine number is greater than 2 m2 / mg. The carbon black according to the invention is preferably used for the production of water-based printing lacquers and water-based inks for mechanical and manual writing and drawing apparatuses. The combination of properties produces a carbon black of high dispersion capacity in water-based bonding systems. The lacquers, printing dyes and printing inks manufactured with them, have outstanding storage stability

Description

OXIDATIVELY POST-TREATED SMOKE BLACK DESCRIPTION OF THE INVENTION: The invention relates to a post-oxidatively treated carbon black for application as pigment and lacquers, printing colors and inks for example for inkjet printers. In lacquers and printing colors, black smoke is used for its outstanding properties. Pigment blacks are available in a large selection with different properties. Different methods are used for the manufacture of pigment smoke.

More frequent is the manufacture by oxidative pyrolysis raw carbon black substances containing carbon. Here the raw substances of black smoke are incompletely burned at elevated temperatures in the presence of oxygen. To this class of processes for the manufacture of hum black belong for example the blast furnace carbon black method, the gas carbon black process and the flame black carbon method. Substances of carbon black, aromatic, multi-core, are used as the raw carbon black substances which contain carbon. In the blast furnace process incomplete burning is performed in a reactor coated with highly fire resistant material. For this in 'a pre-burned chamber is REF. : 30328 generates by the burning of a fuel / air mixture a stream of hot exhaust gas, where it is sprayed or injected the substance of carbon black. The carbon black that forms is cooled by the water spray in the reactor and separated from the gas stream. The process of black blast furnace smoke allows the manufacture of hum blacks with a wide range of the technical properties of carbon black. Flame and gas processes represent important alternatives to the blast furnace process. They produce blacks of smoke, whose properties by a part they coincide with the properties of techniques of the black of hum reached by the process of blast furnace and on the other hand they allow the manufacture of blacks of smoke that are not manufacturable by the procedure of black of smoke of blast furnace The installation for the black Flame smoke consists of a cast iron bowl, which receives the liquid or melted case raw material, and an extraction hood with a refractory wall. The passage of air between the bowl and the extraction hood as well as the eub-pressure in the system serve to regulate the air supply and with this to influence the properties of the carbon black. Due to the heat radiation from the extraction hood, the raw material evaporates and burns partially, but is basically transformed into carbon black. To separate the black from hum, the process gases containing carbon black conduct a filter after cooling. In the process of carbon black, the raw material of the carbon black is first evaporated in a stream of carrier gas containing hydrogen and then in a multitude of small flames under one. Cooled cylinder s burning. A part of the carbon black produced is separated in the cylinder, another part is dragged by the separated process gas in a filter. The important properties for judging pigment smoke blacks are the color depth My (according to DI 55979), the intensity of the color (preparation of a d black smoke paste according to DI EN ISO 787/16 and evaluation according to DI EN ISO 787 / 24) the oil requirement (according to DIN EN ISO 787/5 the volatile constituent part (according to DIN 53552), the structure as DBP adsorption (according to DIN 53601 or ASTM D2414) the size of the average primary particles (by evaluation of microscopic electron capture) and the pH value (in accordance with DI EN ISO 787/9 or ASTM D1512) Table 1 shows the field of properties achievable by the aforementioned black pigment smoke procedures. Table 1 compiled from technical publications of different smoke black manufacturers obtaining the characteristic numbers of hum blacks post-treated in a non-oxidative manner.

TABLE 1 Important application and technical properties of a lacquer or of a printing color are the stability of the dispersion of carbon black in a system of agglutinating agent (storage stability) and the rheological behavior of the lacquer or of the printing color (viscoeity and thixotropy). They are influenced decisively by the quality or nature of the surface of the carbon blacks. The surface chemistry of the carbon blacks depends a lot on the selected manufacturing process. In the blast furnace carbon black process, the carbon black is formed in a strongly reducing atmosphere, while in the smoke process the atmospheric oxygen has free passage to the black smoke formation zone. Correspondingly, the blacks of smoke already present directly after the manufacture an essentially greater content of surface oxides than the blacks of the blast furnace smoke. The surface oxide is essentially carboxyl, lactyl, phenol and quinone groups, which leads to an acid reaction of the aqueous black dispersions. In a smaller quantity, the blacks of smoke also have basic oxides on the surface. The surface oxides form the so-called volatile constituents of the smoke black, which can be desorbed from the surface by melting the carbon black at 950 ° C (DIN 53 552). The content of the volatile constituents has an important influence on the dispersibility of the carbon blacks especially in aqueous systems. The higher the content of carbon blacks in the volatile constituents, the lower the hydrophobic nature of the carbon black and the easier it will be to disperse them in water based binder systems. For the reasons mentioned, the pigment smoke blacks are subsequently treated oxidatively, in order to increase their content of volatile constituents. Nitric acid, nitrogen dioxide and, in a lesser applicability, ozone are considered as oxidation media. The contents given in Table 1 of the volatile constituents and of the pH values can also be increased by an oxidative post-treatment. The oxidation behavior depends decisively on the manufacturing process of the carbon black. In the blast furnace process, the content of volatile constituents can only be increased by approximately 6%. Est reports US 3, 565, 657 on the oxidation of blast furnace blacks with nitric acid. The highest content mentioned in those volatile constituent patents was 7.6% by weight. In many patents, it was sought to conform the properties of carbon black based on a high volatile content of the smoke blacks by the ozone treatment of blast furnace carbon blacks. To this type belongs the US patents 3, 245, 820, 3364, 048; 3,495,999 According to US 3, 245,820 the volatile content of the blast furnace blacks by 4.5% by weight could be increased by ozone treatment. Another important property of the carbon blacks is their spherical surface, which is obtained by different means of adsorption. In the determination of the nitrogen surface (BET surface according to DIN 66132) the coating of the surface of the carbon black with nitrogen molecules is started, where the need for a known place of nitrogen molecules makes possible a calculation in mVs.- Position that small nitrogen molecules can also penetrate the pores and slots of the carbon black, this method also includes the internal surface of the carbon black. An increased need for nitrogen is ammonium cetyltrimethyl bromide (C ). The surface of the CTA (measured according to ASTM D-3765) is obtained as close as possible to obtaining the geometrical surface without pores. Therefore the CTA surface is very well related to the size of the particles and allows conclusions about the technical application of the carbon blacks. Iodine adsorption, indicated as an iodine number, and a third method for the characterization of the carbon black surface. The iodine number is measured according to ASTM D 1510. It is strongly influenced by surface groups adsorbed PAH. With this, the adsorption measured in mg / and not in m2 / g is calculated. Usually iodine adsorption is only given by carbon blacks with volatile constituents of less than 1.5% by weight and a toluene extract of less than 0.25 by weight. Due to its senesability with respect to the volatile surface groups, iodine adsorption can also be used. possibility of characterization for blackened oxidized smoke coe content of volatile constituents. It is the task of the invention to offer blacks for printing lacquers and dyes, which exhibit improved dispersion behavior and water-based binder systems and by means of improved lance time stability characterize the lacquers and d colors. print made with those blacks of smoke. This task is solved by means of a black oxide subsequently treated oxidatively, which is characterized in that its content in volatile constituent parts is greater than 10, preferably greater than 15% by weight in reference to total weight, and the proportion between its surface CTAB The number of iodine is greater than 2 ms / mg. Preferably, the ratio of the CTAB surface to the iodine number is greater than 4 m2 / g. Furthermore, these carbon blacks do not have any concentration of basic surface oxides. The CTAB surface and the iodine number are measured here according to the mentioned ASTM standards. It is important that the carbon blacks before the measurement were not subjected to any thermal treatment to remove the adsorption of the volutilee constitutive parts. It was found that the combination of qualities required of the volatile constituent parts and of a minimum ratio of the CTAB surface to the number of iodine in carbon blacks leads to their being dispersed very easily in water and that this dispersion even for days remains stable. This high storage stability of the aqueous black smoke dispersion makes the carbon blacks according to the invention especially suitable for the use in lacquers colors or printing dyes and inks for writing typewriters and thus for example printing inks for printers of ink jet, felt pen and spherical pen. The carbon blacks according to the invention are obtainable by oxidation with ozone of the carbon blacks. The blast furnace blacks are not suitable as starting material, since in them the content of volatile constituents also by oxidation with ozone n can exceed about 7 to 8% by weight. By corresponding measurements in commercial pigment smoke blacks from different manufacturers it can easily be shown that the combination of claimed qualities was not known until now. Such measurements are indicated in Table 2.

TABLE 2 - Properties of commercial pigment carbon blacks It is worthy to note in this list the smoke commercial smoke black FW 200. It is here a smoke black d smoke not oxidized with ozone. Despite its high content of volatile constituents it does not show the required ratio of C / 'iodine. The invention will be explained in more detail by means of the following examples: Figure 1, Apparatus for oxidation of carbon blacks with ozone. Figure i shows a flux bed apparatus suitable for oxidation in the form of charge of the black of hum with ozone. It consists of a cylindrically shaped treatment vessel that is vertical (D. This has at its lower extremity a part of fluidization that leaves from a cylindrical transversal section towards a truncated-shaped jacket (2) running down, a body of displacement (3 in the form of a cone that runs upwards and is applied to the truncated one and at least one introduction tube (4) which tangentially ends in the essential part in the lowest place of the fluidization part, for the treatment gas On the treatment vessel (l) there is a part of stilling (5) with an outlet tube (6) for the outlet gae. Through the inlet supports of the carbon black (8), carbon black can be introduced into the treatment vessel. The figure (9) indicates a sensor for regulating the height of the current bed. For the generation of ozone, treatment gas (air or oxygen) is conducted before the penetration into the treatment vessel through the ozone generator (7). ) The treatment vessel has an internal diameter of 8 c and a height of 1.5 m. With the apparatus shown in Figure 1, the carbon black is oxidized by charge. By means of a suitable conformation of the fluidizing bed a continuous control of the process can be carried out. For the oxidation test, an ozone producing device with the following loading data was used: operating pressure: max 0.6 bar max. Cover quantity 600 1 / h cooling water 40 1 / h (15 ° C) max. Operating temperature 35 ° C generator voltage 16 kV The concentration to be achieved in ozone depends on the voltage of the generator, the amount of carrier gas and its oxygen content. With a voltage d generator of 16kV with the use of air a maximum of 12 ozone per hour and with the application of oxygen a maximum d 25 g ozone / h. Example 1 The carbon black FWl se. The oxide in the apparatus of Figure 1 at different times with ozone and then analyzed the technical properties of carbon black. In all the oxidation tests, the ozone apparatus was operated with a constant air quantity of 310 Nl / h. The fluidizing bed was charged each time with 200 g of black smoke. The reaction temperature remained in all the tests in the zone between 20 and 30 ° C. Table 3 shows the results obtained after treatments of different duration of F 1 compared to an untreated FW 1 and carbon black d gae oxidized and commercially available FW 200. According to Table 3 the following dependence on the duration of ozone oxidation was observed Increase in volatile content Decrease in pH value Increase in CTAB surface Decrease in the number of iodine Decrease in the intensity of the dye DIN Decrease in the need for oil-Clear variation of the composition of surface oxide The variations of the CTAB surface and the iodine number do not mean that the oxidation with ozone has varied the size of the particles and with this the surface both when the effects are opposite. Much more by the modification of the carbon black surface is influenced so strongly by iodine and CTAB adsorption that the numbers obtained are no longer any measure for the surface. However, they are suitable for obtaining, together with the content of volatile constituents, additional information on the type of modification of the surface by the treatment with oxidation.

In highly oxidized carbon blacks the My value increases to 328. With the increasing degree of oxidation, the composition of the surface oxide also varies. The carboxyl and quinone groups increase strongly, while the phenolic groups and the basic oxides decrease. The content of lactoles remains almost unchanged. The carbon black FW 200 which is not oxidized with ozone shows a completely different proportion of the CTAB surface and number of iodine, which can be attributed to the different composition of the surface oxide. Application Example A special advantage of the carbon blacks according to the invention is their easy dispersion in water and the high stability of that dispersion. To verify this behavior, the so-called tank tests were carried out with the carbon black according to the invention. For this, it was dispersed each time in 99 ml of gram-black water and a cross-linking agent with ultrasound for a duration of 5 minutes, and then the dispersion of the dispersed carbon black was observed. The beakers used had a volume of I50ml and a diameter of 5 cm. Then, after 15 minutes, a deposit of carbon black was present in the non-oxidized carbon blacks with ozone. A clear black-free layer of smoke was formed on the top edge of the liquid level. In particular, the deposit relationships are given in Table 4. TABLE 4 Depository relationships of different carbon blacks 1 F: Black blast furnace smoke 2) G: carbon black gas In the smoke black oxidized with ozone according to the invention even after a week there is no carbon black deposit.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (4)

1. CLAIMS Having described the invention as above, s claim as propria what is contained in the following claims: l- Oxidized post-treated carbon black, characterized in that its volatile constituent content is more than 10, preferably more than 15% by weight with reference to the total weight, and the CTAB surface ratio to the number of iodine is higher that 2 ma / p? g.
2. 2. Black smoke according to the claim characterized in that the ratio of its CTAB surface and iodine number is greater than 4 m2 / mg.
3. 3.- Black smoke treated subsequently oxidatively obtained by the oxidation of a carbon black smoke ozone.
4. 4. Use of the carbon black according to one of the preceding claims, in lacquers, printing dyes and inks for mechanical and manual writing and drawing apparatuses.