A Better Resin for Heatset Gel VarnishesThe raw material for ER-125 manufacture is Gilsonite resin, a naturally occurring hydrocarbon material, well known in ink making for its excellent carbon black dispersing abilities. Gilsonite resin itself is a wide variety of different types of hydrocarbon molecules which may be characterized into two major types: straight chained aliphatics and ring-structured aromatics. Gilsonite also contains a small amount of impurity content, about 0.5%, and a small amount of light oils. American Gilsonite Co. has isolated and separated out the aliphatic hydrocarbon molecules in Gilsonite via a solvent extraction process to make ER-125. ER's manufacturing process also removes the impurities found in Gilsonite, removes the light oils and their smell, and flakes out this new resin (removing Gilsonite's dust). ER-125 resin has been proven by major printing ink companies in Europe, the U .S. and Asia to replace the hydrocarbon resin (C5 - C9's), phenolic resin and even alkyd resin from offset ink formulations.
In addition to these advantages, American Gilsonite and its German ink consultants have shown that ER - 125 resin has some extraordinary ink making properties, consi dering that it is a hydrocarbon - based resin. One major advantage is that ER - 125 resin is reactive with gellation agents such that it can provide "rheological structure" to ink systems. Rheological structure is a combination of viscosity and yield value. Vi scosity is a measure of a system's resistance to flow. Yield value is a measure of a system's thixotropy. It can be thought of as a "gellification index" that tells how far away the system is from being a Newtonian liquid, like water. For example, the yiel d value of water is 0, whereas the yield value of whipped cream is very high, meaning the whipped cream has structure, or can be gelled.
The ER - 125 resin can be used to create gelled varnishes that have increased structure at a low initial tack level, a g reat benefit for fast running heatset inks. Also, these varnishes provide high gloss levels to the ink film and resist the ink degrading or breaking down when it is used on fast - running printing presses.
Why do ink makers want varnishes with rheological s tructure? Ink varnishes with increased structure give the final heatset inks the necessary body to flow between the many rollers of a printing press without breaking down. Usually, the high shear forces of the many rollers of a printing press break down an ink and cause it to fall apart, making it become less of a paste and more like a liquid. Therefore, the ink maker wants a certain high structure to increase the ink's ability to resist degradation caused by the high shearing rollers. Normally, in order to achieve this high structure, ink makers often use less soluble hard resins, which change the performance of the ink.
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