It is also an alternative to the secondary accelerator N,N’ diphenylguanidine (DPG), say experts in LANXESS’ Rubber Chemicals business unit. DPG is widely used in the manufacture of fuel-saving silicon tires, but is not suitable in combination with silanes such as Si 363. Furthermore, DPG can give off aniline under vulcanization conditions. Vulcuren does not exhibit this effect, which many customers do not want.
“Consumers around the world are becoming increasingly aware of the important role that tires play in reducing the fuel consumption of automobiles,” explains Dr. Thomas Brackemeyer, Head of Global Product Management Specialty Products in LANXESS’ Rubber Chemicals business unit. “Tire development is influenced, among other things, by the tire labeling system soon to be introduced in Europe. At present, only green tires with silicon technology are expected to achieve good classifications. Formulation development is very innovative in this area.”
In the production of “green tires”, the hybrid crosslinker Vulcuren from the Leverkusen-based specialty chemicals group has already earned a good reputation as a very balanced anti-reversion agent and a scorch-proof secondary accelerator. Vulcuren optimizes vulcanization during tire manufacture and also functions as an anti-reversion agent to improve product performance. It generates thermally stable carbasulfane crosslinks in the elastomer matrix that are not subject to the typical rearrangement reactions of vulcanizates that are crosslinked with sulfur.
“In high-performance tires, for example, this additive provides effective protection against the slow hardening of SSBR rubber, which, with increasing age, can have a negative impact on, among other things, the product’s wet grip properties,” says Brackemeyer. In its function as a secondary accelerator, Vulcuren also supports the development of tires with low rolling resistance based on silanes such as Si 363. “In the course of this development work, it is expected that Vulcuren will replace N,N’ diphenylguanidine as an established secondary accelerator. Thanks to its compatibility with the other ingredients in the rubber formulation, Vulcuren represents an excellent alternative to N,N’ diphenylguanidine,” explains Brackemeyer.
In replacing N,N’ diphenylguanidine as the secondary accelerator in silicon tread mixes, Vulcuren offers two additional benefits – it opens up new opportunities for innovative silanes in the development of advanced tires, and prevents the release of aniline under vulcanization conditions. “Vulcuren and DPG are based on two completely different kinds of chemistry. For users who are aware of the aniline problem and are looking for a new secondary accelerator, Vulcuren represents a tried-and-tested alternative with an excellent track record,” continues Brackemeyer.
LANXESS (lanxess.com) is a leading specialty chemicals company with sales of EUR 5.06 billion in 2009 and currently around 14,400 employees in 23 countries. The company is represented at 42 production sites worldwide. The core business of LANXESS is the development, manufacturing and marketing of plastics, rubber, intermediates and specialty chemicals.