ELASTOMERS AND PLASTICS Improved Contact Mechanisms of high Viscous Rubber Com pounds on Calender Roll Surfaces by using different Tackifier – Part 2

In Part 1 of this publication ( [1] KGK 3/2021) it was reported about different tackifier classes with regard to their performance to create tackiness in highly filled silica hard-rubber compounds for processing. In addition to influence the rheological properties of compounds, the migration- and blooming tendency during storage time is of high importance. Part 2 deals with the tack behavior in dependency of time, which is investigated and correlated with the chemical compatibility of different mixing ingredients in the compound. To estimate the tackifier so lubility in the used NBR the concept of Hansen Solubility Parameters was em ployed and compared with experimental results. 

After processing, the calendered rubber sheet usually gets stored for a specific time before vulcanisation. Therefore, the blooming and migration behaviour of the tackifier resins and other compound ingredients is of particular importance. Phase separation in the compound could lead to inhomogeneities in the cured product or a bloomed layer on the surface.