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11. September 2019

Lanxess: Material solutions for new mobility, urbanisation and digitalisation

K 2019
Lanxess Hall 6 Stand C76 - C78

The speciality chemicals company Lanxess announced that it will focus primarily on the topics of new mobility, urbanisation and digitalisation. All in all, six of Lanxess' eleven business units – High Performance Materials, Urethane Systems, Polymer Additives, Rhein Chemie, Inorganic Pigments, and Advanced Industrial Intermediates – will be showcasing their products at K 2019.

PU elastomers based on LF prepolymers as an alternative to rubber

The Urethane Systems business unit – a supplier of PU prepolymers tailored to specific customers and applications and used for elastomers, coatings, adhesives and sealants – will be focusing on its low free (LF) technology. This is used to formulate PU prepolymers that contain less than 0.1 % by weight of free isocyanate and fulfill the very strictest industrial hygiene requirements. “These Adiprene LF prepolymers will therefore not be affected by the forthcoming EU-wide restrictions on diisocyanates. At the same time, they improve the mechanical properties of the PU end products. In future, we will therefore be offering all products in the Adiprene LF range, including MDI-based items, with isocyanate contents of less than 0.1 %,” explained Markus Eckert, head of Urethane Systems. Highlights of the business unit’s line-up at the trade show will include a roller coaster car with very abrasion-resistant and dynamically resilient PU wheel coatings based on Adiprene LF pPDI (p-phenylene diisocyanate) as well as very hard-wearing, thermally stable and moisture-resistant star wheels based on Adiprene LF TDI for conveyor and separator systems in modern recycling facilities.

PU wheel treads keep roller coasters on track

Polyurethane wheel treads based on Adiprene LF pPDI keep roller coasters safely on track, even under extreme conditions (Source: Lanxess)

Polyurethane wheel treads based on Adiprene LF pPDI keep roller coasters safely on track, even under extreme conditions (Source: Lanxess)

Roller coaster wheels have to be able to withstand extreme stresses. “We have added tailor-made products to our Adiprene LF pPDI PU prepolymers that reliably meet the requirements of the latest roller coasters in terms of dynamic stress, material fatigue, grip, abrasion resistance and roll resistance,” said Gerald King, head of Application Development and Technical Service for Europe in the Lanxess Urethane Systems business unit. “We have also developed a material and design model with our US colleagues that allows us to predict the characteristics of the wheels and treads and thus support our customers in their material selection and design.”

It is the suspension that keeps roller coasters safely on the track. This usually consists of three pairs of wheels per axle, which keep the roller coaster car fixed to the track in all directions. The running wheels allow the car to move on the track. The side friction wheels prevent the car from derailing in tight curves as a result of centrifugal forces. The up-stop wheels hug the bottom of the rail and ensure that the car does not lift off the track. Due to its dynamic properties, synthetic rubber cannot withstand the high acceleration and braking forces acting on roller coaster wheels and is therefore not used for the treads. By contrast, Adiprene LF pPDI hot-cast elastomers are characterised by very good dynamic performance. They create hardly any heat during frequent, rapid deformations (low hysteresis), so the wheel treads do not overheat during continuous operation. This makes them better able to withstand the loads, and the wheels roll exactly at the intended speed. “The PU elastomers show excellent abrasion, tear and cut resistance, which together with the dynamic characteristics ensures long wheel life,” said King. “This also benefits sustainability because PU elastomers can be recycled into thermoplastic polyurethanes in current test trials and thus contribute to closed material cycles.”

According to Lanxess, with LF prepolymers the polymer morphology can also be more precisely controlled, resulting in a highly structured phase separation between crystalline hard and amorphous soft segments. This is reflected in better physical and mechanical properties of the elastomer parts. Furthermore, the molecular weight distribution is narrower and the physical crosslinking more pronounced. “The viscosity of the prepolymers can be varied widely at a constant isocyanate content and adapted to processing conditions, equipment and desired product properties. In many cases, solvents can be dispensed with when formulating reaction systems,” explained King.

The Adiprene LF pPDI prepolymers are also suitable for other stressed wheel treads and wheels, said the company. “There are good opportunities, for example, with tyres for forklift and order-picking vehicles, guide rollers for high-rise and industrial elevators, and wheels for agricultural machines or in-line skates,” said King. Other possible applications include screen printing squeegee blades and coupling stars.

Durable star wheels for waste sorting

The PU star wheels based on Adiprene LF TDI are characterised by high tear, abrasion and cut resistance and are resilient in humid and warm environments (Source: Lanxess)

The PU star wheels based on Adiprene LF TDI are characterised by high tear, abrasion and cut resistance and are resilient in humid and warm environments (Source: Lanxess)

The Urethane Systems business unit has also developed an alternative to synthetic rubber for producing star wheels for material separation plants and material transport. It is based on PU elastomers produced from Adiprene LF TDI prepolymers. According to the company, the PU star wheels are not only characterised by a longer service life and good mechanical performance, but are also resistant to heat and moisture. In addition to the material, the constructive design of the star wheels also comes from Lanxess. It was developed based on product requirements, technical application and optimisation algorithms using the CAD software Solidworks. “We have already signed contracts with selected processors in North America to ensure that end customers of star wheels benefit from the highest level of quality and performance,” said Michael Timm, global head of Marketing and Development at Urethane Systems.

While the beginnings of the star wheel can be traced back to the reprocessing of old newspapers, they can now be used to separate paper from various household mixed waste (single-stream recycling). The plants used for the single-stream recycling process must be able to handle waste streams at speeds of up to 50 t per hour. The star screen machines used in single stream material recycling facilitys (MRFs) each consist of several steel axles on which the star wheels are mounted. Each deck has its own star wheel arrangement depending on the screen size. In particular, the star wheels of the first screening decks are extremely subject to abrasion because they have to sort out heavier waste components at high running speeds. “A wheel version based on our Adiprene LF TDI prepolymer is used in the plants, which is twice as durable as a component made of rubber. The wheels can therefore be replaced less frequently, which saves material costs and extends the maintenance intervals of the plants,” said Timm. The high wear resistance of the wheels is due to the high abrasion, tear and cut resistance of the PU elastomer.

Advantages also arise during processing. According to Timm: “The long pot life and low viscosities of the Adiprene LF prepolymer system allow controlled processing without the use of solvents. The viscosity can be controlled and specifically adapted to the application. In addition, the PU components are easy to demould, benefiting high productivity with minimal waste.” The use of Adiprene LF TDI is not limited to star wheels for waste recovery and recycling facilities. “We believe that the PU star wheels can also be used in agriculture, for example in harvesting systems or for handling mulch, peat, humus and compost,” explained Timm. Further application opportunities arise in the construction industry, including in the demolition of buildings, in forestry and in very fast production processes for food, beverages and health products.

New flame retardants for insulating materials

Evolutionary development of flame retardants (Source: Lanxess)

Evolutionary development of flame retardants (Source: Lanxess)

Lanxess' Polymer Additives business unit (PLA) is a supplier of products including bromine- and phosphorus-based flame retardants. It will be presenting two flame retardants for rigid PU and PIR foams. According to the company, organic phosphorous compounds are the means of choice for efficient flame retardants for rigid PU foam in order to meet the diverse fire protection requirements in all parts of the world. The oligomeric alkyl phosphate ester Levagard 2000 and the low-viscous, reactive phosphonate Levagard 2100 are said to be on a par with the conventional TCPP (Levagard PP, tris(2-chlorisopropyl)phosphate) with respect to flame height in PIR fire tests as per EN ISO 11925-2 (DIN 4102-B2). In addition, the modern alternatives are barely volatile, if at all, and also exhibit only a low plasticising effect, which is particularly advantageous for rigid PU foams. Even PHT4-Diol (tetrabromophthalate diol), an OH-functional, brominated compound, is suitable for use in rigid PU foams without impairing their mechanical properties. As a reactive molecule, it attaches to the polymer chains via a covalent bond, like Levagard 2100.

In Emerald Innovation 3000, meanwhile, Lanxess offers a polymeric brominated flame retardant for expanded and extruded polystyrene that makes a viable alternative to hexabromocyclododecane (HBCD), which is not approved for use in the European Union. Based on technology licensed by Dow Global Technologies LLC, the product is manufactured via the bromination of an alternating polystyrene butadiene copolymer and has a molar mass of over 100,000 g/mol. With respect to the oxygen index (limiting oxygen index LOI as per EN ISO 4589) and in accordance with EN ISO 11925-2, its flame-retardant properties are equivalent to those of HBCD with the same bromine content.


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