Low Melt Resin
High Melt Resin
H/C Atomic Ratio
When comparing the chemical functionalities of various fractions, classified by softening point, the same basic functionalities are observed, with some differences in relative intensity. To give an example, Figure 2 shows several partial Fourier transform infrared spectra for low melt resin, straight Gilsonite, and high melt resin.
The FTIR spectra of all three materials are quite similar. Figure 2 shows “amide type” carbonyl groups between about 1650 and 1700 cm¯¹.
One of the major applications of Gilsonite is in printing inks, where it is used as a carbon black dispersant, and as a major component of low-rub black newsinks. The two major limitations of Gilsonite in this market have been unstable solution viscosities and – due to the presence of mineral insolubles – the need to filter the Gilsonite solutions. These are costly and inconvenient. A remedy to these limitations has been found in ER-125 Resin, a low melt resin obtained via a solvent extraction process that separates the low molecular weight fraction of Gilsonite .
The effect of solvent extraction on the properties critical to this application is dramatic. For example, the solution viscosities of the three grades of Gilsonite Selects are orders of magnitude higher than those of typical hydrocarbon resins (Figure 3). Even the most stable grade of Gilsonite, Selects 300, more than doubles in viscosity after less than one month standing. Other grades of Gilsonite increase even faster in viscosity. In contrast with that behavior, the extracted resins show solubility viscosity characteristics typical of synthetic resins used in the graphics industry (Figure 4). Not only is the viscosity far lower than that of Gilsonite in its natural state, there is also little or no increase in viscosity over extended periods of time. Coupled with this is the fact that the solvent extraction process makes the resulting ER-125 Resin essentially ash free and thus eliminates the need for filtration.
The net effect of this is two fold: first, it makes it possible for the first time to present a Gilsonite-derived product as a legitimate alternative to synthetic resins in the graphic arts industry; second, it increases the value of the end product far beyond the value of plain Gilsonite while still making it attractive to the end user, since the resin is substantially less expensive than the synthetic alternative.
The issue of color is not addressed by the solvent extraction process. The color of Gilsonite and ER-125 Resin is a given, and so their use should be targeted to those markets that are not sensitive to their dark color, such as black printing ink.
The high molecular weight fraction of Gilsonite that results from the extraction process is a high melt resin called IR-200 Resin. Typically, such products are considered low value byproducts. In this case, the high melt stream retains many of the properties that make Gilsonite unique and many applications for this product exist today.
Solvent extraction is only one of many processes that may be applied to Gilsonite in order to modify it for high value applications. Once the product is considered as a raw feedstock from which specific products can be formulated for specific applications, many possibilities exist. Two among those: