Pigment grades

European matches, mosdy of brown or black tips, are basically identical with U.S. matches ia their formulations, except that they contain ia addition red iron oxide or manganese dioxide of pigment grade ia the match heads (2). Match materials, testing methods, and related matters have been reviewed (7,8). 

The old Bechamp batch process for reduction of nitroben2ene (iron-hydrochloric acid) is obsolete however, Mobay Chemical Corporation is operating a plant using this process for production of pigment grade iron oxide as weU as aniline. 

Titanium raw-material utilization can be broken down as illustrated in Figure 9. About 4% of the titanium mined is used as metal, 94% is used as pigment-grade Ti02, and 2% as ore-grade mtile for fluxes and ceramics. In 1995, the estimated U.S. Ti02 pigment production was valued at 2.6 biUion and was produced by five companies at 11 plants in nine states. About 47% was used in paint, 18% in plastics, 24% in paper, and 18% in other misceUaneous appHcations (56). 

A patent (122) for the production of pigment-grade titanium dioxide describes preparation of titanium tetrafluoride by the reaction of SiF and ilmenite. 

Table 11 Hsts the types and appHcations of special pigment-grade carbon blacks. Included in this Hst are thermal black and lampblack. Over 40 special black grades have been developed based on the furnace process having a broad range of surface areas, from 20 m /g to over 1500 m /g. The lower surface area products are used in printing inks and tinting. The high area, more expensive products find use in high color enamels and lacquers.

Table 11. Types and Applications of Special Pigment Grades of Carbon Blacks...

The plastics industry uses these pigments mainly for polyolefins. The tinctorial strength is comparatively moderate. 1/3 SD HDPE colorations (1% TiOz), for instance, require between 0,22 and 0,7% of these pigment grades. Such colorations are heat resistant up to 300°C. Transparent colorations in 1/3 SD are stable up to 250°C. 

Titanium dioxide is mined from natural deposits. It also is produced from other titanium minerals or prepared in the laboratory. Pigment-grade dioxide is produced from tbe minerals, rutile and dmenite. Rutile is converted to pigment grade rutile by chlorination to give titanium tetrachloride, TiCU. Anhydrous tetrachloride is converted back to purified rutile form by vapor phase oxidation. 

F33B. Gasless incendiary mixture Zr (200 mesh) 41.0, Fe203 (pigment grade, red) 49.0 "Superfloss" 10%... 

FF-30. A std commercial ignition material for 1 Therm 64C consisting of the following compn Ti 30 Fe2Og(red pigment grade 70% Ref Tech Command, ArmyChemCenter, Maryland, Development of an Incendiary Pellet ,... 

Once the proper pH is reached, the slurry can be filtered continuously via a rotary vacuum filtration. A clear KF filtrate can be fed directly to the AQUATECH cell stack. The collected cake is a valuable byproduct. For this case the precipitate is a titanium dioxide which is easily upgraded via washing, drying, grinding and purification to the high value pigment grade Ti0-- Even in the raw form, this byproduct will draw credits of up to 30 /T. 

Natural, minable deposits of chromium oxide are not known. In addition to pigment grade, chromium oxide producers usually also offer a technical grade for applications based on properties other than coloration. These include ... 

The liquor is then separated into discrete particle size fractions by gravity or centrifugal separation residual fine particles are reclaimed by flocculation and filtration. The separated fractions are dried and disintegrated to give pigment grades... 

The increasing demand led to new production processes. The most important process today is the furnace black process. It was developed in the United States in the 1930s and substantially improved after World War II. It is a continuous process, which allows the production of a variety of carbon black types under carefully controlled conditions. Nearly all rubber grades and a significant part of pigment-grade carbon blacks are now manufactured by the furnace black process. Nevertheless, other production processes, such as gas black, lamp black, thermal black, and acetylene black processes, are still used for the production of specialties. 

Specific Surface Area. The specific surface area of industrial carbon blacks varies widely. While coarse thermal blacks have specific surface areas as small as 8 m2/g, the finest pigment grades can have specific surface areas as large as 1000 m2/g. The specific surface areas of carbon blacks used as reinforcing fillers in tire treads lie between 80 and 150 m2/g. In general, carbon blacks with specific surface areas >150 m2/g are porous with pore diameters of less than 1.0 nm. The area within the pores of high-surface-area carbon blacks can exceed the outer (geometrical) surface area of the particles. 

Materials. Titanium dioxide was pigment-grade material (du Pont Ti-Pure R-900 brand) with spherical particles in the range of 0.2-0.5 microns. In most experiments, the material was used without further treatment. In one experiment (specified in the text), the material was dried for 18 hours at 145°C. 

A pigment-grade zinc oxide rotary kiln uses high temperature to produce pigment-quality zinc oxide and makes possible higher recovery than a grate furnace. 

---