After having certified biomethanol-based silicone fluids and emulsions, technology service provider TÜV Nord has approved WACKER chemical group’s resource-efficient manufacturing method for silicone sealants according to the new REDcert² standard.

WACKER’s approach involves determining the mass fraction of raw materials and auxiliaries derived from fossil-based resources and offsetting this with methanol produced from biomass. This makes WACKER the first chemical company to produce the organic components of its sealants exclusively on the basis of plant-based materials instead of raw materials derived from petrochemicals.

Silicone sealants consist primarily of a silicone polymer that cures at room temperature to form a rubber-like elastomer, plasticizers, fillers and additives. Apart from silicon which is manufactured by reducing quartzite with coke, an important raw material for manufacturing the polymer is methanol.

WACKER is the first chemical company to apply a certified mass balance method when manufacturing silicone sealing compounds.

The compound is first converted to methyl chloride, which then reacts with elemental silicon in the Müller-Rochow process in order to produce a mixture of various methylchlorosilanes. These, in turn, serve as starting products for silicone production.

WACKER uses methanol derived both from fossil raw materials and from biomass, which, however, makes no difference in chemical terms, since the molecule is always identical with respect to its structure and properties.

The mass balance method takes advantage of that. If methanol from both plant- and fossil-based sources is used within an integrated production system, the portion of raw materials derived from biomass can be determined and explicitly allocated to individual sales products. The approach is comparable to the green electricity certification system used in Germany. WACKER already uses this method for manufacturing biomethanol-based silicone products for the textile, paper and consumer goods industries.

Technology service provider TÜV Nord now extended its certification to WACKER’s production of silicone sealing compounds. In this case, the certification meets the requirements of the new REDcert² standard. This standard covers not only all of the organic raw materials for silicone manufacturing – it also encompasses all of the other organic components of the formulation.

This serves as verification that WACKER’s silicone sealing compounds are 100% free of fossil raw materials. To qualify, purchased raw materials must have been sustainably manufactured from biomass, and all of the required starting materials must have been obtained from certified sustainable sources. The volumes of raw materials needed for product manufacturing undergo regular audits as part of an annual recertification process.

“Ecological and sustainable construction plays a key part in global efforts to protect the climate. Successful certification of our mass balance method makes us the first company to supply ready-to-use sealing compounds based on non-fossil raw materials,” says Dr. Robert Gnann, president of the WACKER SILICONES business division.

According to Laurent Morineaux, head of the company’s Construction Silicones business unit, the new certificate underpins WACKER’s ongoing and strong commitment to sustainability. “Sealants are among the most high-volume silicone products in our portfolio”, he says.