Gaskets can be printed using ultra low-viscosity HNBR grade from Lanxess

ERJ staff report (DS)

Leverkusen, Germany -- Lanxess AG has created an ultra-low viscosity grade of HNBR, which permits the possibility of printing oil-resistant gaskets. The new grade - ULV Therban AT 3400 VP - offers Mooney grades of less than 1. "It is the consitency of honey, said Dr. Günther Weymans, head of Lanxess' Technical Rubber Products business. He added that the cured material has a well-defined shape, similar to conventional vulcanisates.

Technically, the uncured material has a viscosity of between 100 and 1,000 Pas (Pascal seconds) at conventional processing temperatures. This means it flows 1,000 to 10,000 times more easily than existing grades with Mooney viscosities of around 39 MU (MU = Mooney Units).

The new grade  is currently being manufactured by Lanxess as a trial product for sampling purposes. Thre company has sent sample quantities to potential customers and they are working on specific applications. Weymans said he hoped to see applications in the market around the end of this year. He noted that the crisis has encouraged companies to accelerate their innovation programmes and this may have helped with the acceptance of this product into the market.

  It has potential applications in liquid injection moulding (LIM), the production of in-place gaskets (IPG) and the manufacture of particularly soft seals that achieve a hardness of under 40 Shore A without the addition of plasticisers. This HNBR elastomer, too, is distinguished by its exceptional dynamic properties and very good resistance to aging - both these qualities are valued highly by users of vulcanisates made of existing grades of Therban.

The new grade requires a specific cure package, and careful cure control, but offers such extreme benefits in processing that process aids used in previous HNBR compounds can be eliminated, said Weymans.

He noted that each HNBR molecule is shorter than in previous grades, which delivers the low viscosity, however, the molecular weight distribution is extremely narrow --not just very narrow,but extremely narrow, said Weymans. he added that the molecules have specific sites near their ends, which permit cross-links to form from the end of one molecule to the next. This delivers the vulcanisate performance of a more conventional elastomer.

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Press release from Lanxess