Plastics and/or rubbers and composites typically require the use of additives and/or fillers to prepare viable commercially useful materials. Additives and/or fillers are essential for their processing and have a direct impact on the cost-performance of the final product. Specific and desired aesthetic and/or color can also be targeted through the use of these materials.
Fillers are particulate additives used for a variety of purposes to modify the performance of plastics. Carbon black is widely used in considerable quantities as reinforcing filler in the rubber industry. However, when it is used in, for example commodity plastics, the quantities based on total weight percentage do not normally exceed 4% due to a loss in the mechanical properties of the doped plastic. Carbon black in plastics, for example for high density polyethylene piping or polyolefins for automotive applications does not typically exceed these percentages. In automotive parts' applications, carbon black is used as pigment and as an ultraviolet absorber in a variety of plastics including, but not limited to polypropylene (PP); polyethylene (PE); thermoplastic polyolefin (TPO) (rubberized polyolefin); or their blend; and poly (vinyl chloride) (PVC).
World-wide production of commodity carbon black in 2011 was 14.26 million tones and is expected to grow 5% from 2013-2018. Carbon black is derived from non-renewable resources such as natural gas or petroleum-derived heavy oils through a chemical-thermal conversion. The soot formed in this process is recovered and processed into carbon black. The most common process today is the “furnace black process”. In this process each kilogram of carbon black requires approximately two and a half kilograms of oil. The fossil-fuel carbon black industry is a major contributor to carbon dioxide emissions, which has been implicated in global warming.
Although elemental carbon in carbon black occurs at nanometer scale, aggregate states may occur at the micron scale. In addition, carbon black is produced as fine dust which represents a serious environmental and health risk and hazard if manipulated in this form. A common solution to this problem is to pelletize the carbon black in the presence of binding agents into agglomerates or ‘pearls’ or to produce master batches of carbon black prior to final dosage in plastics. However, those familiar with the technology of using “pearls” of carbon black master batch pellets are aware of the challenges that the plastic industry faces to disperse these carbon blacks during the final dosage for extrusion or injection molded pieces.
The ASTM standard D3350 Section 2 points out that the concentration of carbon black “in carbon-doped” plastics should be higher than 2% by weight in order to provide an adequate UV protection. However, as previously stated, it is known by those versed in this art that the use of carbon black should not exceed 4 wt % (more preferably 3% and even more preferably 2.5 wt %) of the total composition in the case of plastics such as polyolefins, PVC, or similar thermoplastics used for pipes and/or automotive applications. When carbon black is added in excess, it generally reduces the general mechanical properties of the plastics.