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New Processing Additives for Amine Cured Elastomers
During the last decade the use of Special Elastomers has gained specific interest due to raised requirements in achieving resistance against extreme conditions. By far the biggest portion of this high performance Elastomer class is consumed by the Automotive industry because of increasing technical demands under the hood.
In particular, ongoing Engine downsizing and turbo charging of gasoline engines contribute to reduced fuel consumption. However, on the other hand an increased temperature development is observed. Rubber parts under the hood, like turbo charger hoses, seals or gaskets are designed to seal and transport aggressive automotive fluids at increasingly elevated temperatures. In addition a long service life is a basic requirement OEM suppliers have to guarantee.
Nowadays, in order to satisfy these highly severe conditions the use of Diamine based cross-linkers becomes more and more popular as the next generation to Peroxide cure. The commonly used polymer types are based on AEM-, (HT)-ACM, HNBR or FKM rubber. However, all of them suffer from certain processing drawbacks. In particular poor flow, reduced heat stability due to additives needed, and compromised physical properties; in addition, generally inferior release performance from metal parts and mold fouling problems during the Injection Molding process are observed.
New Struktol processing additives for Diamine crosslinked Elastomers were recently added to Schill+Seilacher’s product portfolio. This development took advantage of Struktol’s broad knowledge in Silica dispersion in Tire Tread applications.
Regarding coloured AEM-, HT-ACM or HNBR compounds containing active white fillers, for example Silica, it is generally accepted that Organosilanes are used to connect the filler with the polymer in order to achieve good physical properties. One major benefit of such chemistry is that Compression Set is reduced. However, due to use of Organosilanes on the other hand, other important physical properties (Tensile Strength, Elongation at Break) are reduced in such white filled Special Elastomer compounds.
Struktol HT 750 was developed to overcome the above noted compromises. Due to the new additive’s interaction with the surfaces of active white fillers the dispersion is improved significantly, leading to excellent Compression Set values in combination with good physical properties. Tensile Strength and Elongation at Break are maintained at acceptable levels. In particular looking for requirements in Extrusion applications for hoses the ratio between Tensile Strength, Elongation at Break and Tear Resistance is beneficial.
In addition further benefits in processing are highlighted. Struktol additives contribute to better release from metal surfaces, which is a major requirement in Injection Molding applications as well during the mixing process.