flextec technology

The new benchmark for bonding – Flextec® inside!

With Flextec, Henkel has developed a new, patented basic technology for producing especially user-friendly and environmentally compatible adhesives and sealants. This technology makes use of silane-terminated polymers which allow targeted adjustment of adhesive and sealant properties such as tack and elasticity.

Thanks to the new technology, the products offer a great number of benefits: they are non-hazardous to health, easier to use and compatible with all commonly used substrates. They react with atmospheric moisture and contain no solvents or other critical ingredients, so they are exempt from hazard labelling. For DIY enthusiasts and professional craftsmen this means the dawn of a new age: powerful assembly adhesives that provide secure fastening of a wide range of materials without screws or nails, and parquet adhesives with built-in impact sound damping that allow repositioning thanks to longer working times.

Modularity means flexibility

Simply combining a small number of different elements in different ways can result in a huge variety of finished components. With its Flextec® prepolymers, Henkel has created a modular system that can be used to make many different kinds of products. Flextec® is a high-performance, solvent- and isocyanate-free binder. Using this basic technology, the product developers design the building blocks for polymers, which are one of the main components among the 10 to 15 different constituents of adhesives and sealants.

Flexible polymers

The basic structure of the polymers is relatively simple. Highly reactive silicon groups, also known as silane compounds, are docked onto the ends of polyether chains of different lengths. By modifying the chain structure, the adhesives researchers obtain products with, in some cases, fundamentally different characteristics. The longer the chains, the more elastic the product will be. Technically speaking, the elasticity of a material is expressed by a value called "modulus of elasticity". A high value means that the product is not very elastic. Such materials are suitable for making adhesives. By contrast, materials with a low elasticity modulus, i.e. the more elastic ones, are used in the production of sealants. The number of chain branches, on the other hand, affects product strength: the more branched the chain, the stronger the product.

The scientists control the speed at which adhesives and sealants react and cure by varying the molecule types – methoxy groups, for instance – linked to the silane compounds at the ends of the chains. An assembly adhesive, for example, must have immediate holding power (high instant tack) if the user wants to do something like bonding a shelf to a wall. A parquet adhesive, on the other hand, is designed to allow the floor layer to make adjustments for some time during the installation process.

Modular system with Henkel know-how

Further components, or additives, in adhesives and sealants include fillers, which determine the mechanical properties and consistency of the product. The addition of UV stabilizers makes the products resistant to solar radiation. Working according to the modular principle, the specialists put together the components as required to achieve the desired product characteristics. Henkel's special expertise lies in selecting the relative quantities of these components and their particular chemical composition.

Advantages over polyurethanes and silicones

Products based on Flextec® technology have properties that are comparable to those of polyurethanes and silicones – but without their shortcomings. For instance, the polymers also adhere to almost all substrates, but have a far greater UV stability compared to polyurethanes, making them also suitable for outdoor applications. Moreover, they adhere extremely well to damp substrates, can be painted and bonded over, are compatible with paints and coatings, and are detachable. They do not become brittle at low temperatures and thus exhibit what the experts call "cold flexibility".

Also suitable for problem applications

Moreover, these innovative products can be used wherever polyurethanes or silicones fall short: in particularly difficult bonding situations such as underwater sealing, e.g. sealing fire protection pond liners or swimming pools. Other possible applications for these products include sealing leaks in cold storage units or liquefied gas tanks