102
New Reactive Processing Additives Based On Organo-Silicones
The idea of combining several features in one molecule is not a new concept. However, to pool both improved processing and enhanced crosslinking properties in an organo-silicone based material is a novel approach in rubber.
Organosilicone based processing-additives have been widely used in the rubber industry since many years in order to achieve better properties in processing or improved release performance during the injection molding process. Overall this substance class offers a couple of benefits especially if processing issues are of concern.
Besides the mentioned benefits, this substance class reveals one major drawback. Organosilicones may suffer from blooming effects, especially if higher concentrations of processing additives have to be applied for an optimal processing. This might be necessary for example if the compounder is forced to use high filler levels in order to comply with certain standards. In this case due to partial incompatibility with the polymer matrix a migration of the Organosilicone based processing additive to the surface is observed. This is a highly undesired effect since contaminated surfaces result in poor paint or coating adhesion and other unwanted behavior, which is especially of high concern in the automotive Industry.
Summarizing the target behind this new material class; we aimed to make full use of the mentioned benefits of Organosilicone based materials and to overcome the major disadvantage of unwanted blooming to the surface of the rubber compound.
In order to prevent the new material from any migration to the surface, the new material class offers the ability for crosslinking into the rubber matrix, due to the fact that it consists of crosslinkable units suitable for peroxide vulcanization. Consequently any migration to the surface is prevented.
In addition to processing benefits, substances based on the new Organosilicone based material class may also enhance the physical properties such as tensile strength, modulus or compression set. Independently of the ingredients of the rubber compound the ratio of tensile strength to elongation at break maybe shifted into positive directions. This might be an advantage if compliance with a special standard is required.