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Building on Sustainability – with Silicones and Polymers

Weather is becoming more extreme. According to the World Meteorological Organization, the years from 2010 to 2019 were the warmest decade since record keeping began in 1850. In November 2019, the European Union declared a climate emergency – as had other countries and municipalities prior to that.

The complexity of the task makes climate protection an ambitious mission. Yet there is a great deal that can be done beyond altering our political trajectory. WACKER’s innovative construction chemicals contribute to more sustainable buildings and homes.

Mission 1: Consuming Less – Using Renewable Raw Materials

Anyone wanting to build more sustainably needs to take one lesson to heart more than any other: reduce your consumption of raw materials.

Today’s new technologies and materials make that possible. One very simple example from our everyday lives illustrates how that works. Tile adhesives are used in our bathrooms, kitchens, swimming pools and workshops. “Our new binders allow tile installers to use the modern thin-bed method,” explains Dr. Tobias Halbach who works in the WACKER POLYMERS division developing new technologies for construction applications. This means that builders use less tile adhesive and work more economically and sustainably. The thin-bed method requires a layer of adhesive just two to six millimeters thick, whereas with the thick-bed method, the adhesive layer can be up to 30 millimeters thick. The thick-bed method is still used at four out of five construction sites worldwide, revealing a great deal of potential for conserving raw materials.

Dispersible polymer powders are capable of more than that, however. Dr. Halbach: “Combining the thin-bed method with about 3 percent of our binders is all it takes to reduce consumption of sand and cement by up to 90 percent.” Plus, he notes, many tile adhesives require additives to ensure a bond and prevent sagging. “We’ve developed our binders to the point that we can dispense with some of these additives without sacrificing quality,” says Halbach.

That feature is important for one current trend in particular: large tiles are very popular at the moment, even though they are more difficult to install. The experts at WACKER have addressed this by developing dispersible polymer powders that make their adhesives highly resistant to sagging. The adhesive, in other words, does not drip when applied on walls. At the same time, the dispersible polymer powder also lends the cured tile adhesive the flexibility it needs to absorb stress – an important characteristic if tiles are to resist shocks and breaking.

“We’ve developed our binders to the point that we can dispense with additives without sacrificing quality.”

– Dr. Tobias Halbach

Another industry trend is the increasing emphasis that builders are placing on materials made from renewable resources. WACKER offers solutions here as well. Environmentally sustainable solutions are carrying the day more and more often, particularly for interior wall paints. “We’ve even created a new product line for polymer dispersions based partially on renewable raw materials: VINNECO®,” says Dr. Markus Busold, who is responsible for strategic marketing within the WACKER POLYMERS division. “We use bio-acetic acid to create these kinds of binders.” Bio-acetic acid is a byproduct of the woodworking industry, which means it is produced without cutting down any additional trees.

The trees serving as the base material for the bio-acetic acid are from certified forests located within a radius of 400 kilometers of WACKER’s Burghausen site – the acetic acid that WACKER uses, in other words, is based on the PEFC® system for sustainable forest management.

“Our bio-acetic acid is identical to that obtained from fossil-based raw materials,” Busold explains. In subsequent steps, WACKER uses this material to produce vinyl acetate-ethylene, or VAE for short. When used as a binder, the polymer dispersion optimizes cohesion between all of the components in wall paints and ensures that the paint will remain on the wall permanently when applied.

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The market for biobased paints and coatings is growing – at an anticipated average rate of over 4 percent per year between now and 2024. For this reason, WACKER has developed another process for producing binders from renewable raw materials. “To that end, we’ve been cooperating with Dynaplak, a Dutch company which uses plant-based starch. The starch accumulates as a residual product of potato processing,” Busold says. This natural polymer possesses binding properties that the experts at Dynaplak optimize. “We combine the refined starch with our VAE polymers to create a new hybrid binder,” he explains. The advantage here is that the starch reduces the proportion of VAE required by one-third – and that, in turn, reduces consumption of fossil raw materials.

Mission 2: More Energy Efficiency – Less Carbon Dioxide

Protecting the climate also means using energy more efficiently and releasing fewer greenhouse gases.

Over half of the energy that buildings need is in the form of heat, and much of that heat is lost – especially through the facade. “The better a building’s insulation, the less heat it requires. The use of an external thermal insulation composite system, or ETICS, can reduce energy consumption by up to 30 percent or more,” says Halbach. When installed on a building’s exterior, these systems prevent walls from cooling too much in winter or heating up unnecessarily in summer. For the thermally insulating properties to have their full effect, adhesion between the individual layers of the composite system has to be firm. “Our binders make sure that happens,” he explains. At the same time, the polymers also make the adhesive mortars and renders/plasters flexible, which is why WACKER binders are the key to an insulating system that remains stable over the long term.

Water-repellent treatment of concrete

Silicones from WACKER Likewise Play an Important Role in Building Insulation

In this regard, silicones make the insulating materials used – glass wool or mineral wool in particular – hydrophobic, i.e. water-repellent. “Everyone understands the benefit: a dry sweater keeps you warmer than a wet one,” says Dr. Rudolf Hager, who heads the Construction Chemicals unit at WACKER SILICONES. The numbers back that up: a single square meter of damp, uninsulated brick wall increases energy consumption by twelve liters of heating oil per year. For a single-family home with an exterior surface of roughly 180 square meters, consumption jumps to more than 2,000 liters of heating oil annually.

Because mineral wool is non-flammable, it is an extremely popular insulating material. Products made with biobased binders do not tolerate moisture, however. For this reason, WACKER experts have developed silicone emulsions that protect mineral wool from moisture and thus from microorganisms.

“Our silicones do more than just improve the insulating properties of the material – they also make it possible to use mineral wool in a damp environment.”

– Dr. Rudolf Hager

External insulation is not right for every facade – listed buildings, whose appearance cannot be modified, are one example of this. Silicone resin emulsion paints and silicone-based water repellents from WACKER can still be used in these types of structures to reduce heat loss. The reason? Silicones keep facades dry. They also leave vapor permeability unaffected. “The facade can breathe,” he says. “That’s important in terms of a good indoor climate, and it makes the building fabric last longer.”

Mission 3: Fewer Harmful Substances – Healthier Living Space

Building more sustainably also means using as many non-toxic products and ingredients as possible. Minimizing the use of harmful substances is WACKER’s number one priority. “At the same time, however, we still aim to maintain at least the same level of quality and functionality,” says Dr. Arndt Schlosser, who heads up the Sealants and Adhesives unit within WACKER SILICONES. “Wood-flooring adhesives are a good example of this: thanks to hybrid polymers from WACKER, they can now be formulated without any isocyanate or solvents. Formulations don’t need tin catalysts anymore either.”

Schlosser’s team has already developed additional applications for hybrid polymers: liquid waterproofing systems. These watertight, seamless, continuous membranes protect the building fabric – ranging from below- and above-ground walls, balconies and patios all the way up to the roof – preventing damage caused by moisture. In these applications, they can replace conventional sealing systems that contain substances of toxicological concern or volatile organic compounds (VOCs). “In developing our hybrid polymers, we now have an innovative sealing system that contains no plasticizers or solvents,” Schlosser explains. The sealing system forms a barrier to water, one of the greatest enemies of buildings, defending the latter from mold and improving thermal insulation.

“We’ve formulated our products to make them more environmentally compatible and have even improved their curing behavior.”

– Dr. Arndt Schlosser

  • A – Adhesives: Silicones and polymers make adhesives functional, versatile and sustainable.
  • B – Architectural Coatings: This polymer technology combines high product performance with low emission values.
  • C – Paper: Vinyl acetate is ideal for paper and board applications.
  • D – Sealants: Silicones ensure airtight windows
  • E – Technical Textiles: VINNAPAS® offers flexible solutions to meet the challenges of the nonwovens market.
  • F – Carpeting: Polymeric dispersions optimize the strength and flexibility of carpets.

There are numerous applications today where builders can turn to solvent-free adhesives and sealants from WACKER. Alkoxy-based silicone sealing compounds can be used for integrating window frames into masonry, sealing glass and doors, or installing new kitchen countertops.

The experts at WACKER are constantly working to enhance their formulations. “We’ve formulated our products to make them more environmentally compatible and have even improved their curing behavior,” he points out. At the same time, the resulting joints stand up to the toughest demands, whether purely mechanical or caused by temperature fluctuations. In this way, the silicone sealing compounds help extend the life of the whole building.

Testing a wall paint

While water may be the enemy of the buildings, most wall paints do contain water-based binders.

“The drawback here is that water provides a breeding ground for microbes and bacteria,” Busold explains. This is why biocides are usually added to increase the paint’s shelf life. As the painted wall dries, however, the biocides escape into the ambient air. The experts at WACKER have now developed an interior wall paint in powder form. “Now we can stop adding preservatives and biocides,” he observes. This is because powder paints are not dissolved in water again until just before they are applied to walls.

As a result, all that escapes when they dry is water. Another advantage of the powder form is that it does not freeze in cold conditions or thicken in response to heat, as traditional wall paints do.

Each mission harbors its own unique challenges. Taken together, they all contribute to greater sustainability and help advance efforts to protect the climate.

The Dubai Model House Project

Sustainable construction in the Middle East

That is the goal which brought the WACKER Group and state-owned Dubai Central Laboratories (DCL) together. The story behind the initiative begins with Energy Strategy 2050 – a program launched by the government of the United Arab Emirates with the aim of increasing the proportion of clean energy in the overall energy mix to 50 percent by 2050 and reducing the carbon footprint of energy generation by 70 percent.

Diagram of a model house

The project included a one-year study on two small model houses. Beginning in August 2018, the study allowed researchers to compare conventional and sustainable construction materials. One house was not insulated; a standard paint was used for its interior and exterior walls; and its doors and windows were sealed with a standard sealing compound.

On the sustainable house, by contrast, the team installed an external thermal insulation composite system. The paint used for the facade provided protection from moisture and environmental influences. The team also applied a polymer-modified cementitious waterproofing membrane to the floor, and on top of this, they installed a layer of tiles using the thin-bed method. The interior walls received a coat of low-odor paint requiring no organic solvents. A highly durable, weather-resistant external sealant was applied around the doors and windows.

Air-conditioning systems kept the temperature at 23 degrees Celsius in both houses. The DCL experts then recorded energy consumption, interior temperature and humidity, ambient temperature and humidity, and volatile organic compounds (VOCs) for each.

Results Were Available After the One-Year Test Phase:
The sustainably built model house performed much better than the house built with traditional materials. One particularly impressive finding: energy consumption for the insulated model house was nearly 60 percent lower than that of its conventional counterpart – thus reducing CO2 emissions by an equivalent amount.