WACKER unveils biocompatible, liquid silicone rubber for the production of radiation-sterilizable valves

Munich, August 5, 2011 – At this year's international trade fair for high-tech solutions for medical technology, COMPAMED, Munich-based chemicals company WACKER will be unveiling a new liquid silicone rubber for radiation-sterilizable silicone valves used in medical devices. The product, available under the name SILPURAN® 6610/40, serves in the production of biocompatible silicone valves whose slits do not close up or "heal" during radiation sterilization. The new silicone rubber allows such valves to be made without the use of additional auxiliaries. For instance, silicone valves ensure that infusion systems administer the correct dose of liquid medication. COMPAMED 2011 takes place in Düsseldorf, Germany, from November 16 to 18.

Medical equipment for administering liquid medication frequently employs valves made from silicone elastomers. These offer high dosing accuracy, are biocompatible and can be very readily sterilized on account of their resistance to heat, radiation and chemicals. However, it is not unknown for the slits of such silicone valves to close up ("heal") when radiation-sterilized, a common practice in medical technology.
What's more, the higher the radiation dose, the more the slits close over. This can impair the dosing accuracy of the valve and may even cause it to fail completely. Consequently, valve manufacturers have so far resorted to a process auxiliary which prevents opposing slit edges from touching. The auxiliary is a liquid or particulate release coating which is applied to the edges of the slits as they are being created in the membrane.

The advent of SILPURAN® 6610/40 silicone elastomer obviates the need for a release agent. This liquid silicone rubber is so durable that the valve slits will not even heal when exposed to radiation doses far in excess of those usually employed in sterilization. This non-healing effect is the outcome of a special formulation of the liquid silicone rubber and also allows the silicone valve membrane to be slit prior to post-curing. The valve slits can be created either with a suitable mold during injection molding itself or with a punching die after demolding.
Eliminating the need for a release agent makes it possible to produce silicone valves in SILPURAN® 6610/40 much more quickly, cleanly and inexpensively than before. SILPURAN® 6610/40 lowers the risk of contamination that is associated with release agent, such as when the valve is being made or installed in medical equipment.

Valves need to be particularly accurate when used for dosing medicines. Those made from SILPURAN® 6610/40 can be sterilized with ionizing radiation prior to shipping, without suffering any loss of dosing accuracy. As a result, needle-free infusion systems and insulin pumps, along with other medical equipment that employs silicone valves, offer a high level of patient safety. There is no
possibility that the equipment will fail through radiation-induced valve healing.
Like all SILPURAN® products, the new SILPURAN® 6610/40 liquid silicone rubber is biocompatible according to selected ISO 10993 and USP Class VI tests. The two-component product is produced in white and is packaged in cleanrooms.

SILPURAN® – Silicone Products for Medical Applications
WACKER has put special measures and its new WACKER CLEAN OPERATIONS production standard in place to ensure that the SILPURAN® silicones will continue to meet high standards and ever-rising safety demands in the future, too. All SILPURAN® silicone rubber is dispensed or packaged in cleanrooms to prevent contamination by airborne particulates. 50-micron filtering, visual inspections and, for solid silicone rubber, the use of antistatic, welded in-liners ensure the best-possible levels of purity.
SILPURAN® silicones are free of organic plasticizers, are radiation-resistant, can be readily sterilized and are biocompatible according to selected ISO 10993 and USP Class VI tests. According to ISO 10993, the materials were tested regarding cytotoxicity, pyrogenicity and sensitizing properties. USP Class VI tests included the examination of acute systemic toxicity, intracutaneous toxicity, and short-term implantation.

For further information, please contact: Wacker Chemie AG Press and Information Florian Degenhart Tel. +49 89 6279-1601 Fax +49 89 6279-2877 florian.degenhart@wacker.com Brief company profile: WACKER is a globally-active chemical company with some 16,300 employees and annual sales of around €4.75 billion (2010). WACKER has a global network of 26 production sites, 20 technical competence centers and 50 sales offices.

WACKER SILICONES Silicone fluids, emulsions, rubber grades and resins, silanes, pyrogenic silicas, thermoplastic silicone elastomers WACKER POLYMERS Polyvinyl acetates and vinyl acetate-copolymers in the form of dispersible powders, dispersions, solid resins and solutions for binders for construction-chemical products, paints and surface coatings, adhesives, plasters, textiles and nonwovens, as well as for polymer materials based on renewable resources WACKER BIOSOLUTIONS Biotech products such as cyclodextrins, cystein and biopharmaceuticals, and also fine chemicals and polyvinyl acetate solid resins WACKER POLYSILICON Polysilicon for the semiconductor and photovoltaic industries Siltronic Hyperpure silicon wafers and hyperpure silicon monocrystals for semiconductor devices