Polyurethane professionals and engineers from a range of industries went to a two-day workshop organised by Dow and Polytec EMC Engineering at the Hyperlast Birch Vale systems house in June.
Jane Denny reports.
Dow Hyperlast’s Birch Vale facility – part of Dow’s Formulated Systems segment – is a UK systems house located in the Peak District.
A £1.5m investment in the facilities in 2012 built a new R&D centre dedicated to engineering elastomers and PU technology innovation. The company offers on-site trialling and testing facilities and supplies customised plant machinery
The polyurethane knowledge base at Hyperlast was cultivated through the development and production of a catalogue of products over several decades. Solid engineering elastomer development began at Hyperlast in the 1970s and fully integrated into Dow soon afterwards. Intended as a replacement for plastic-based materials in applications like filter housings. One of its first uses under Dow leadership was as an insulation for Shell UK’s subsea pipelines in the early 1980s.
Andrew Davies, Dow’s lead application development chemist, describes Hyperlast as “the engineer/chemist’s interpreter.” It employs chemists, polymer technologists and engineers to devise chemical systems for Dow clients, explains Davies.
Dow’s two-day elastomer workshop
Engineers and technicians from mainland Europe and the UK attended the two-day workshop which was organised by Dow Chemical in collaboration with polyurethane machinery maker Polytec EMC. Austria-headquartered Polytec designs, develops and manufactures custom-engineered machinery for producing polyurethane components, as well as the products themselves.
Spin-cast and moulded polyurethane manufacturer BMP Europe, the European Polyurethane Technologies Group and the California-headquartered Teledyn, which specialises in defence and aerospace components sent team members to the workshop.
The MacArtney Group, based in Rotterdam, develops underwater technology solutions. It serves energy companies including oil and gas industry players and coastal or ocean-based renewable energy projects. The company’s cable assembly technician Bart Dijkstra said he found the workshop useful.
He said there was significant value in the technical observations of material performance Dow technicians shared. He said: “I discovered from this the variety of materials and uses for Dow chemicals.
“I learned that when trying to choose a material for a specific purpose, sometimes you need to look further than the basic needs the material has to fulfil,” Dijkstra added.
Dijkstra came with questions about materials being used in current MacArtney Group projects and was given one-on-one guidance. He said: “They ran some trials for us while I was there.”
Dijkstra continued: “We were really allowed to get our hands dirty and with experts from Polytec EMC on hand we learned some very helpful tricks on using Polytec’s equipment.
“We were able to have one-on-one conversations with Dow and Polytec EMC experts about how to get the best of out of our materials and that was really useful,” he added.
Dijkstra said the host even demonstrated with a new material its technicians developed for pipe coating. “The technicians were demonstrating the material’s ability to react quicker which meant the machinery was able to deliver more layers of PU.”
Attendees watched demonstrations ranging from rudimentary hand mixing of PU compounds to the hypnotic formulation of a layered elastomeric product on rotational moulding system.
The Rotakoting machine is a two-component version of Polytec DG103 Twin Drive, according to Marcin Grigoriew, Hyperlast’s product development specialist.
He told Urethanes Technology International magazine that Dow’s newly-patented thermosetting polyurethane – Rotakote P 5600 – is a polyurethane/polyurea system designed to produce high performance elastomeric coating for paper and steel industry rollers.
Given the high load bearing properties and high temperature resistance required for steel industry rollers and the hot-wet conditions components must perform to in the paper industry, ensuring a mechanical property match with the application’s need is vital, said Grigoriew.
“In terms of mechanical properties, we needed a stronger more resistant to abrasion and compression set retention after ageing and hot water exposure.
“We’ve developed three Rotakote P5600 system grades - 70Shore D, 95Shore A and 90Shore A. It’s not TPU and it is not syntactic. To achieve even better results with this technology, we’d recommend a three-component machine with heated mixing head. Polytec EMC has a great deal of experience in this area,” he added.
Birch Vale capabilities
Hyperlast is a polyurethanes elastomers systems business with a product line which covers applications in both concrete and metal coatings. Products from Dow’s Hyperlast range are used globally in automotive, civil engineering, manufacturing, marine, offshore, rail, transport and many other industries.
Typical uses include, anti-slip coatings on pedestrian walkways at train stations and car parks or in ballistics protection. In the marine industry polyurethane systems are used to form coatings for marine fenders and component encapsulation.
Dow Hyperlast also provides customised elastomers and polyurethane systems including damping and nose reduction solutions for high performance automobile applications. It also provides customised materials for construction and soft tooling moulds. Dow products can be found across the industrial spectrum from rail and waterproofing to marine and maintenance coating applications.
Hyperlast brands include XiTRACK which binds the loose ballast around railway lines. Developed by XiTRACK and Dow Hyperlast, the product reacts and holds ballast solid in about 20 seconds, according to user Balfour Beatty.
The Dow PIG - a pipe cleaning product made from the DIPRANE 54 Series polyurethane elastomer, is a particular highlight in Dow Hyperlast’s history.
Hyperlast testing confirmed that a using quasi MDI prepolymer instead of traditional TDI polyester for pipe cleaning pigs meant it would last twice as long.
Test results show that Diprane 53 quasi MDI prepolymer Pigs ran 160 miles of pipeline and showed only mild signs of wear. A Pig made with a traditional TDI compound needed replacing after running half the pipe’s distance.
Trialling and testing facilities
Both static and dynamic testing of materials can be undertaken at Birch Vale. Product and component testing is also a large part of the company’s day-to-day activities said Davies. The company also carries out physical testing to qualify and benchmark material properties.
Davies believes in the possibilities of polyurethane elastomers. He is confident that polyurethane chemistry offers “considerable possibilities in customising and engineering elastomers.”
In terms of its properties, Davies said the material is capable of outperforming rubber in terms of “abrasion resistance, cut and tear resistance, ozone resistance, microbial resistance and chemical resistance.”
An engineer’s view
Gareth Roberts, senior engineer R&D at Dow, has worked in the company for 15 years. He specialises in product development for OEMs and Tier 1 customers. As part of the workshop, Roberts outlined the importance of choosing the right polyurethane for the application at hand.
Highlighting the potential for disaster from using the wrong material, he recounted the tragedy of the seven astronauts aboard NASA’s space shuttle Columbia in 2003. He said investigators found that the point of failure was in a rubber sealing system.
Explaining the significance of the different kinds of stress and strain a material may be subjected to before failure, Roberts outlined the finer points of the tensile data the company builds for a range of clients, adding that this property is the most commonly researched by Dow for its clients.
Citing examples such as buffers to stop trains at stations and depots, Roberts explained how calculation of the potential compressive stress-strain on the 75A Hyperlast 101 would yield about a 13mm deflection of the pad while for the 80A Hyperlast, deflection would be 11mm.
Roberts said for this scenario, Dow advice would be to use Hyperlast 101/80 for the first trial. Roberts added: “If not entirely suitable, we might then have offered a slightly softer, more resilient thermoplastic for the job.”
He said Dow Hyperlast provides advice on the best choice of material, including how a material ages or reacts in the mould. According to Roberts, the relative shore hardness of a thermoplastic material remains an “extremely poor” analysis.
Urging attendees to keep it simple and revert to the basic principles. Davies, and Paul Fitzgerald, global brand manager for elastomers, advise reverting to traditional guidelines even when working with second generation materials.
The STORMS checklist is a Dow-formulated process for ensuring the best possible outcome for polyurethane processing of any kind. An acronym for the stages in polyurethane production from the initial stirring of the compound, prompts for ensuring optimum temperature, moisture tolerance and pointers for ensuring the accurate ratio of materials.
It’s a memory aid,” said Davies. “It ensures vital processes are adhered to in polyurethane production.”
Starting from the point polyol and curative mix, through the process of ensuring temperatures match Technical Data Sheet requirements, to the final mixing of the compound, Dow’s workshop outlines the importance of STORMS in practical terms.
S – Stir Polyol
T – Temperature Control
O – Operator Engagement
R – Radio Control
M – Moisture Tolerance
S – Stir components Together