by Liz White, editor
Polyurea was an essential component in the successful development of a new fantasy-based water-feature called Wakobato at German theme park Phantasialand – site of the PDAEurope’s 2009 conference. Delegates to the event heard a presentation about this novel development, and also had the chance to experience Wakobato’s weird architecture and somewhat grotesque characters for themselves.
“The versatility of polyurea helped us build the attraction in a time and cost-effective way,” commented Karl Gerniers of design group the Three Dee Factory, who designed the feature.
Visitors sail through Wakobato on a boat with a water gun and are invited to hit as many of the Stonehenge-based constructions which make up the attraction as possible, said Gerniers.
The Wakobato attraction, built in 2008 and put in service in spring 2009, is sited on a lake and consists of a number of floating tombstones and frog-guardians around ‘Stonehenge Island’
Gerniers described the complexity and size of the elements of Wakobato, made possible, he said, by the combination of EPS (expanded polystyrene) foam for the sculpting and polyurea as protective membrane.
Parts are finished with colour-stable decorative finishes.
Discussing the project, Gerniers said, “Polyurea is a new material for me. But I am a believer now!” Polyurea offers architects, designers, artists the advantage of a fast process, from design to sculpting, with freedom of design for details and aesthetics, Gerniers said.
Originally, Three Dee was going to make the sculptures with glass-fibre-reinforced polyester (GRP).
But the project involved making a huge number of parts, in a limited time. Stability in water is also obviously important. As a result, with GRP, the total project cost was too high.
Using polyurea, the company decided to build the prototype in EPS, spray it at polyurea systems house Flexguard and prove the performance. It passed the evaluation testing and also met the budget, Gerniers said.
Gerniers was able to show the 120 delegates at the Polyurea meeting a demonstration at Phantasialand of the step-by-step build up and also showed how to use it in a totally different project – making furniture using polyurea.
Adhesives in the fast lane
Polyurea adhesives may be in line to replace structural adhesives for the wood-processing sector — if manufacturers take the plunge and decide to invest in new equipment, indicated Stephan Buser, who is responsible for development of chemically curing adhesives at Nolax AG of Sempach-Station, Switzerland.
Noting that modern assembly lines for wood products are fast, efficient and characterised by high process reliability, Buser said that the structural adhesives employed in such lines can be a concern.
“Their curing time often determines the speed of the entire process.” Nolax has evaluated use of polyureas as adhesives in such sectors with highly promising results, as detailed at the PDAEurope meeting.
Wood-processing appears to be a highly attractive field for chemically curing adhesives for two main reasons, Buser said.
- High reaction rates allow for a continuous manufacturing of wood elements such as prefinished parquet, wood plates or beams.
- Fast continuous production allows for a lot size of 1, reducing stock and giving flexibility.
But since traditional production equipment is not suitable for such fast adhesive systems, new manufacturing concepts and tools have to be developed, he noted.
Pointing out that polyurea is known in the industry to form tough coatings with excellent resistance against chemical and environmental influences, Buser explained that these aspects prompted Nolax’s decision to explore its potential as an adhesive for substrates such as metals, glass, wood, ceramics, etc.
“We found a vast number of formulations suitable for almost every purpose,” he said.
His conclusions were that:
• Polyureas are excellent wood adhesives;
• Polyurea glue lines are emission-free;
• Polyurea adhesives are not highly critical with respect to temperature, moisture, laminating pressure, and more; and
• They provide a high process reliability.
But Buser stressed that in order to use polyureas, wood-processing equipment has to be purpose-built, and that this needs major capital investment. Also, the Nolax expert pointed out, polyureas are yet to be certified for engineered wood applications.
Case study: desalination rehabilitation
In April 2009, Israeli company Sya Group Ltd completed the rehabilitation of 12 000 m2 of pools and channels at a desalination facility in Ashkelon, 5 km from Gaza, in the south of Israel.
Sya Group’s Eliezer Nisensvieg described this project to the delegates at Brühl, pointing out that challenges for this work included a tight schedule since down time is critical and highly expensive.
Also, the project had to be carried out in conditions of high humidity and moisture, with flowing water.
Other aspects to take into account were safety in underground work and air supply.
As delegates at the PDA-Europe meeting have heard before, meticulous preparation is essential, and exposed steel rebars have to be dealt with.
Nisensvieg also noted the crucial need to measure the dew point and control surface temperature.
Sya successfully completed spraying of a 6000 m2 area in 7 days, including surface preparation, concrete rehabilitation, surfacing and spraying. The group will also spray a further 6000 m2 next March, said Nisensvieg, concluding that, “Quality assurance and on-site inspection save time and money.”
Greece gets on the polyurea map
For Greek company Viopol, its first polyurea use was bedliners on two pick-up trucks in 2007.
Viopol’s Christos Kaharamanoglou also described the company’s first pool coated with polyurea. The company has been building swimming pools since 1975, and he described a current polyurea project for a pool made of polycarbonate sheets with a base made of concrete.
The surface coating, Elastocoat C 6430/100, is an aliphatic polyurea system applied in two layers by roller, with a 2-hour recoat window.
Advantages of the system, according to Kaharamanoglou, are that it is fast to apply, seamless, easy to clean, resistant to chemicals and UV stable.
Kaharamanoglou also gave examples of floating pontoons for marine decks, which are cement structures filled with EPS. Other projects include spray coatings on a 4000-m² roof of a shopping mall in Larissa, in Greece, in 2008, and a 4000-m² roof in 2009 for a Holiday Inn in Nicosia on Cyprus.
Cutting noise and secondary containment
The Dutch government has issued a new regulation called PIEK, limiting the noise levels allowed during loading/unloading of commercial vehicles in urban areas, as described by Cees Moorman of Elastogran.
The government has specified a maximum level at times from 19.00 h to 23.00 h of 65 dB(A), and at night time, from 23.00 h to 07.00 h, of 60 dB(A).
To meet these new requirements, Elastogran has developed a sound absorbing coating, with the same wear- and rolling-resistance as traditional flooring. Elastogran showed that polyurea applied on a lorry floor and walls gives levels of 54dB(A), while on a lorry tail-lift it gives levels of 58 dB(A). Approved trailers get a clearly visible PIEK sticker, Moorman noted.
Looking at uses of polyurea for secondary containment, Moorman said that in 2008 new legislation in the Netherlands came into force for the storage of hazardous substances, labelled PGS-15, which in Germany is used as water regulation WHG-19.
Secondary containment “provides a barrier between a store of chemical liquid and the environment,” noted Moorman, adding that a leak-proof polyurea liner is often used to completely surround the store of the chemicals.
As an example, he noted a floor made of prefabricated concrete slabs, with steel edges at the joints. These were filled with a mastic joint filler. The floor was then made waterproof and chemically resistant with polyurea.
Moorman said that polyurea coatings offer the benefits of being waterproof and able to bridge cracks, with durable chemical resistance.
They also offer rapid application, which is valuable in such projects because to cope with weather conditions and allow the building programme to progress.
Other uses outlined by Moorman were a parking deck application at Schiphol Airport, where a waterproof membrane was used to stop leaks, a mushroom farm, where the waterproof membrane was used to stop steam and chemicals leaking into the soil, and on a highway bridge deck, where a water membrane under the bitumen protects the concrete from cold and water.
Waterproofing of all types
German company VIP supplies polyureas in a range of forms: as high-performance spray coatings — both pure and hybrid types, as joint fillings, and for roller applications.
Andreas Reisenzahn is in charge of developing new markets for VIP’s coatings and 2-part adhesives in industry, construction and dealerships. Typical projects include infrastructure repairs, for example on potable water/ wastewater handling, secondary containments and pools, wellness and spa areas, he said.
One case study Reisenzahn described was the coating and joint sealing of 28 800-m² of potable water tanks for a desalination plant in Qatar in the Middle East, carried out in May/June 2009.
Demands in this project included a potable water- certified and fast-curing surface coating with no VOC content. Once the joints had been filled with VIP’s QuickFill and primed, the area was flooded with salt water for testing. Next the concrete was prepared using primer, followed by an aromatic coat of QuickSpray using Graco equipment. Finally after 24h the tanks were filled with potable water.
For the leaking 98 000-m² roof of a shopping mall in Dubai in October 2009, the customer wanted to avoid damaged stock, slip hazards and any long-term structural damage.
VIP first cleaned the existing failed membrane and removed irregularities and sharp projections. Next a new 1.5-mm tightwoven polypropylene geotextile was laid out over the existing membrane, and coated with QuickSpray 2-part polyurea hybrid/ pure polyurea (no primer required). This resulted in a tough, seamless, waterproofing layer. A flood test was successful with no water ingress after 36h, said Reisenzahn.
PDA-Europe event well attended
The Polyurea Development Association (PDA) Europe achieved 120 visitors and 11 exhibitors – two more than last year – for its third annual conference, held 16 – 18 Nov in Phantasialand, Brühl, Germany, and commented that “polyurea shows no sign of crisis.” Highlights of the event included a new course on the surface preparation of concrete as well as presentations covering chemistry and raw materials, fire safety and European requirements for coatings. Polyurea experts presented case studies on desalination projects, pool lining, silent floors, and roofing uses. A major attraction was the uses of polyurea on the Wakobato statues – a new Phantasialand feature.
KILLED BY BUREAUCRACY
The EAS (European Acceptance Scheme) for materials in contact with water, has been “killed by bureaucracy,“ according to Josef Klinger of the German water technology centre, DVGWTechnologiezentrum Wasser (TZW).
The EAS was intended to be a single EU-wide ‘harmonised’ system for approval of materials in contact with water, but after many years of committee work and research, this has now fallen by the wayside, Klinger indicated.
In 1998, the Drinking Water Directive (98/83/EC, Article 10) left requirements for materials in contact with drinking water up to member states, who could fix stricter demands for their national regulations.
For market reasons, representatives of the sectors involved, including coatings, began to try to devise a single European acceptance scheme for hygienic assessment of products coming into contact with drinking water — the so-called EAS.
But the efforts of a Regulators Group on Construction Products in Contact with Drinking Water (RG-CPDW) and an Expert Group (EG-CPDW) were not fruitful.
Klinger said the current situation is that different national requirements still have to be fulfilled. But four member states are trying to find a “voluntary” route out of the blockage, he noted.
These states (Germany, France, the Netherlands and the UK) aim to find a common approach and implement this in national schemes, with mutual recognition possible. Other states could join, but “there is still a long way to go,” said Klinger.
Materials and products for drinking water applications have to have the desired mechanical and especially hygienic properties, noted Klinger.
Germany has a “well defined approach,” which requires each substance used for the production of a material to be assessed toxicologically, and the composition checked against positive lists. Leaching tests are carried out in cold and warm or hot water, with specified limits, before products are certified.
Germany’s coating guidelines were last updated 7 Oct 2008, Klinger said. They include: • Composition of the positive list for organic coatings; • How to include new substances in the positive list; • Requirements for organic coatings; • Test Certificate; The Positive List – Part 1 includes: 1.1 Starting substances for resins and curing agents — Isocyanates, Polyols, Alcohols, Oxirane and Glycide Compounds and more; 1.2 Fillers and pigments — Federal Institute for risk assessment BFR recommendations to be met.
Modifying agents, solvents, additives and accessory agents plus intermediate products are included, Klinger noted. The smallest components susceptible to migration have been included in the positive list according to their toxicological assessment. This includes intermediates with epoxy groups, amines and isocyanates, said Klinger.
CONTROVERSIAL BUT NECESSARY
Discussing many aspects of fire resistance regulations and testing, Jérôme De Boysère of Thor Group noted an important point to consider for polyurea coatings. They have, until now, mostly had requirements in regard to their reaction-to-fire (for example Euroclass B, or German B1), but not (yet) in regard to fire resistance, he said.
But if coatings are applied on existing load-bearing structures, such as concrete or steel, “one should carefully check if the coating does not degrade the fire resistance of the substrate,” he emphasised.
Privately owned Thor Group claims to be a world leader in industrial biocides and flame retardants for textiles.
De Boysère, whose role is to develop Thor’s FR business for the plastics industries, also stressed that a good reaction-to-fire does not ensure fire resistance properties and that this applies to inorganic materials as well.
Also, he said, the use of FRs in polyurea is relatively recent and has not been extensively explored.
Describing the FR challenge, De Boysère said selection of FR and formulation work is a complex, empirical process, involving considerable “trial and error,” and often subject to difficult compromises.
Aspects which must be heeded include compatibility with host polymer and processing; FR efficiency and fire test performance; eco-toxicity; and cost aspects.
Fire statistics show that there is a fire every two minutes in Europe. In Germany fire kills about 600 victims every year. The main cause is poisoning through fire gases (CO and more) with about 6000 burn victims. The economic cost (2000, source: GDV) is about €6000 million, a third of that in insurance, said De Boysère.
Looking at the controversy surrounding FRs, De Boysère said it is undisputed that FRs save lives and property. Concerns exist, however, about the environmental impact and toxicity of certain FRs, as a result of scientific studies in Germany, the Nordic area, the UK and Switzerland, concerning aspects such as persistence, bioaccumulation, toxicity (PBT). Other concerns focus on the potential formation of halogenated dioxins and furans, and on FRs found in the environment. This discussion mainly focuses on halogenated FRs, but also on a few phosphorus FRs, he said.
Noting that there is also a political agenda here, De Boysère pointed to the EU’s risk assessments of 13 high-volume FRs, and to REACH implementation.
He also referred to the fact that OEMS making consumer products, are more and more adopting a proactive “halogen-free” stance.
De Boysère concluded that:
• Flame retardants are an essential part of passive fire safety in a world made of plastics;
• Their use is dictated by a complex framework of regulations (national laws, industry standards);
• Material testing is subject to a variety of fire tests (depending on final use and related fire scenarios) which in turn affect the FR strategy;
• The use of FR in polyurea is relatively recent;
• Systems exist but most are subject to further improvements;
• Many R&D activities are going on and are expected to result in improved formulations; and
• Polyurea users should seek advice from raw material producers, formulators or FR suppliers.