At ABRAFATI 2015, the WACKER Group is presenting a range of innovations for challenging coatings and sealants: Wood impregnated with the new silicone resin emulsion SILRES WH is protected against damp, moisture and damage caused by fungi and insects for an exceedingly long time. Another local premiere is the new silane-terminated polymer binder GENIOSIL XT for industrial adhesives and liquid waterproofing systems. Additional highlights are the dispersible powder VINNAPAS 5518 H for hydrophobic skim coats and the dispersions VINNAPAS EZ 3112 and VINNAPAS EZ 3066 for intumescent coatings. ABRAFATI is being held from October 13 to 15 in São Paulo, Brazil.
New silicone resin emulsion SILRES WH provides wood with long-lasting protection against moisture and damp, as evidenced by the beading effect on impregnated wood (right). In contrast, the untreated wood (left) soaks up wet immediately. By providing long-term protection, SILRES® WH greatly reduces the frequency of renovating and recoating exterior woodwork.
At ABRAFATI 2015, WACKER is showcasing a range of polymer- and silicone-based products for the first time on the American market. SILRES WH, a novel silicone resin emulsion for wood protection coatings, possesses hydrophobic properties that reliably protect wood outdoors against wet and damp and the damage that these cause. The product is flexible enough to adhere strongly to wood surfaces, and imbues them with the water-repellent properties typical of silicones. Weathering tests show that the product still protects impregnated wood against moisture and damp after 17 years. This means that silicone resins, which have proved successful at protecting mineral substrates over the decades, can now provide wood with lasting outdoor protection, too.
The 50-percent emulsion is based on a functional silicone resin and can serve as a water-repellent impregnating agent or as an additive for formulating film-forming wood stains. Due to its hydrophobic properties, SILRES WH reduces the water uptake of wood and so keeps its water content low. Consequently, the wood is better protected against typical damage, such as fungus, mildew and insect attack, as well as cracks caused by swelling and shrinking. The use of biocides can be slashed as a result. SILRES WH added to paints and wood stains confers lasting water repellency, even in low concentrations.
The water repellency is clearly revealed by the beading effect the emulsion produces on wood surfaces after weathering. The new product greatly reduces the frequency of renovation and repainting compared with conventional wood preservatives. Best results are obtained by diluting it 1:4 to 1:9 with water. In waterborne stains, SILRES® WH is admixed in amounts of up to three percent.
Extremely tear-resistant and highly elastic: GENIOSIL® XT
Another highlight is the GENIOSIL XT line: the new products are based on silane-modified polyether with a high density of crosslinkable silyl groups and represent the first technically equivalent alternative to conventional polyurethane-based systems. By virtue of their properties, the new polymers are ideal for applications that repeatedly subject them to dynamic forces – up to now, applications of this kind were essentially the domain of isocyanate-curing polymer systems.
GENIOSIL XT’s low viscosity makes it easy to process at low temperatures. The binders can be formulated with and without plasticizers or fillers, and blends can be produced in any color. The compounds can be formulated for adhesion to many conventional substrates, such as metals, glass, cement, glazed tiles, wood, polycarbonate, and polymethyl methacrylate. Priming is unnecessary. As the polymers are also miscible with all other GENIOSIL silane-terminated polyethers, compounders can vary the properties over a wide range of formulations. Typical end products are industrial adhesives, liquid waterproofing systems, and coatings.
GENIOSIL XT 50, for example, is an alpha-silane-terminated polymer and lends itself to the production of tin-free adhesives and crack-bridging liquid waterproofing systems. These can possess tensile strengths of up to 9 N/mm2 and tear strengths of up to 50 N/mm (measured in accordance with ASTM D 624 B-91). What is more, GENIOSIL XT 50 can be formulated without fillers to make transparent, tin-free end products that have good mechanical properties.
Skim coats are cementitious products applied with a low thickness of 1-2 mm to walls to reduce undulations and to create an ultra-smooth finish before a paint coat is applied on the top for protection and esthetic appeal. Modern skim coats are increasingly modified with polymer binders to enhance the workability and elasticity – this is essential in new buildings, where some movement is still to be expected.
VINNAPAS 5518 H is a dispersible polymer powder that exhibits great workability, good adhesion to all substrates, greater flexibility and flexural strength. Furthermore, it shows optimized cleaning properties and is thus much easier to wipe after film formation. Due to its strong hydrophobicity, skim coats modified with VINNAPAS® 5518 H prevent moisture and dirt particles from penetrating the surface of the facades – which results in an improved weather resistance, and therefore durability of buildings. This makes it particularly suitable for challenging outdoor applications such as skim coats.
Intumescent coatings are special fire protection coatings which encase steel girders and swell (intumesce) in the event of a fire, thus delaying the melting or warping of the building’s supporting structure. The coating is usually applied one to four millimeter thick and, when subject to heat, foams to tens to hundreds of times its original thickness. Because of the extremely low thermal conductivity of the foam layer, the temperature in the interior of the coating increases only slowly, so that the steel girders are protected against the heat of the fire for a defined time, and thus retain their strength for longer.
The polymer dispersions VINNAPAS EZ 3112 and VINNAPAS EZ 3066 show particularly pronounced foaming and expansion, and long-term foam stability. At the same time, the adhesion and strength of the intumescent coatings are improved, so that the protective layer firmly adheres to the substrate and forms a heat barrier for a limited time. Without the binders, the foam layer would be too brittle and in-adequately adhere to the steel substrate. Both binders are water-based and free of organic solvents or additives, such as plasticizers. VINNAPAS EZ 3112 further offers the additional advantage of high hydrophobicity and a very good shelf life even under challenging storage conditions. Depending on the formulation, both dispersions allow for highly fire-resistant coatings with fire resistance class F120 (heat protection for up to 120 minutes).
SILRES BS 168 Improves the Wet Abrasion Resistance of Interior Paints
WACKER has also developed an interior paint additive for pH adjustment with zero odor and zero VOC properties (volatile organic compounds). Thanks to its high alkalinity (pH value: 13), SILRES BS 168 is highly efficient, combining lower dosages, high pH stability, and paint storage properties. It can also be pre-diluted in water (dilution rate: up to 1:3) for better dosage control. SILRES BS 168 itself does not contain volatile organic compounds and therefore doesn’t affect the paint’s VOC content. The product also interacts with the fillers and the resin in a coating formulation, positively increasing scrub resistance properties of the dried film.
