News (Sponsor type)

The Wacker Group presented two new impact modifiers for composites at this year's JEC World edition: Genioperl (registered trademark) W37 and Genioperl W38. Both products represent a new generation of silicone-based additives that significantly improve the mechanical properties of thermosetting resins.

Impact modifiers improve the shock and impact resistance of composite parts. This is also true for Genioperl W37 and Genioperl W38. Both products were developed to optimise the durability and performance of thermosetting resins such as epoxies and vinyl esters. Their tailor-made molecular structure based on a functional silicone building block promotes efficient phase separation and forms nanoscale elastomeric domains in the resin matrix. These increase the toughness of the matrix and prevent the composite from breaking under impact. Genioperl W37 and Genioperl W38 are therefore suitable for demanding composite, adhesive and coating applications where mechanical reliability, fatigue resistance and low-temperature performance are required.

Sustainability was also taken into account when developing these modifiers. Wacker significantly reduced the cyclics content in both products. Genioperl W37 and Genioperl W38 disperse easily, are compatible with organic resin systems and work reliably even at low dosages. For processing, simple stirrers can be used just as well as rotor-stator systems. Neither mechanical strength nor viscosity or heat resistance of the material is affected by this.

Genioperl W37 improves the impact strength of thermosetting polymer systems, especially in low temperature ranges. The recommended additive amount in thermosets is between 2 and 8 percent by weight, based on the unfilled resin-hardener or polymer system. Due to the low amounts used, effects on the viscosity of the reactive resins and the glass transition temperatures of the cured products are negligible. Processing temperatures of at least 50°C are recommended for optimum dispersion.

Like Genioperl W37, Genioperl W38 also improves the impact strength of thermosetting polymer systems at very low temperatures. Here too, the recommended additive dosage in thermosets is between 2 and 8 percent by weight. Genioperl W38 also contains additives to reduce foaming, which is especially important for casting processes under reduced pressure.

Powersil Resin 710 for heat-resistant moulded parts

Another focus product at Wacker’s booth is Powersil (registered trademark) Resin 710. Using the silicone resin compound, moulded parts can be produced by compression moulding, pressure gelation or even injection moulding. The material is suitable for thermal class R components, which are able to withstand temperatures of up to 220°C for extended periods of time.

The new product is an alternative to high-temperature-resistant polymers such as PTFE (polytetrafluoroethylene) and PEEK (polyetheretherketone). Components manufactured using the new product are characterised by good electrical insulation properties, mechanical strength and UV stability. Powersil Resin 710 is solvent-free and not subject to labelling requirements. It comes with a low viscosity, which facilitates processing. The material is available either as a peroxide-curing version for the production of heat-resistant, ready-to-use parts or as a variant that cures with small quantities of a standard silicone catalyst.

At JEC World, Wacker also presented the following high-performance additives and binders for the composites industry:

• Silres silicone resins for improving the electrical insulation properties and flame retardancy of composite materials,
• HDK (registered materials) pyrogenic silica for reliable rheology control,
• Vinnapas low-profile additives to minimise shrinkage and improve the dimensional stability of composites,
• Geniosil (registered trademark) organofunctional silanes for adhesion promotion and for treating fillers and fibres.

Cover photo: Powersil Resin 710 (source: Wacker)