Ingo Kleba, managing director of small-medium-sized systems house Rühl Puromer, quoted this comment, and went on to prove that this is indeed the case.
His enterprise currently has more than 800 active systems formulations, covering soft, rigid and fibre-reinforced materials, and regards itself as a pioneer in the PU sector. For decades “we worked with SMEs to find the best way to use PU chemistry to solve their problems, with a constantly enlarging field of applications,” Kleba said.
Rühl is fascinated by the diversity of possible applications, said Kleba, who with his colleague Thomas Mack ran through some novel uses the company has been involved with over the years at the FSK event.
“More than 20 years ago, we received an inquiry about using polyurethane for manufacturing crash test dummies,” to simulate the human body, which could be crashed at a predetermined speed.
These are fitted with sensors and the force absorption and resultant deformation of the dummies measured to obtain information on crash loads and thus the safety of passengers.
Rühl has also made foam for external breast prostheses needed after breast cancer surgery. “As you can imagine, in such a use there is a lot of psychological stress,” so people would like a very good replacement to help counter this, Kleba said. Rühl developed a PU foam filled with barytes for the customer, Amoena – a major maker of these devices – adjusting the softness of the foam to meet the customer’s needs. But the material initially failed to meet regulations on biocompatibility and cytotoxicity.
After further work, Amoena’s lightweight forms are now covered in a supersoft PU film, which the company says has “a natural silky look that is soft to the touch and is extremely flexible.”
Mack noted that use of polyols based on renewable resources (natural oil polyols NOPs), is an area that, “in our experience suffers constant ups and downs.” Rühl has had project requests that get rejected when the customer realises that implementation will result in higher system costs.
A project in 2001 attempted to develop a PU - rigid integral skin foam system with 70 percent of the polyol as NOP. The question was: “Will this be cost effective?” Mack said.
Rühl successfully developed a two-component PU formulation using different soya-oil based polyols from Hobum, to make hard integral foam parts for the automotive industry, especially for bus interiors. While that fulfilled the needs in terms of mechanical properties and processing, it did not get into serial production.
But this project was valuable experience for Rühl in using NOPs, gaining know-how for later projects.
Mack noted that, even in LFI technology, use of NOPs is possible, and here work on fibreglass rovings has extended into sisal types.
The Rühl expert commented that generally, while customers like to reference use of renewable resources “no one is willing to pay the slightly higher material costs.”
Nevertheless as raw material costs rise, the NOP option becomes more attractive. In addition, Rühl’s work means it is ready when the occasion arises.
Kleba commented that use of the LFI honeycomb technique is growing rapidly, with honeycomb insertion becoming automated. A combination of reinforced fibres in a PU matrix is being used for the rear parcel shelf of Audi-3 series — also using a system with NOPs. Another application here is a roof part for convertibles.
Load floors also widely use this type of honeycomb construction, and Kleba thinks Asia will be a big market for these in future.
Rühl approaches new customer projects as unusual challenges. It does not ask “Have we a system for this application?” As a provider of tailored solutions, the approach is: “What features or specification must the material satisfy?” Kleba concluded.
‘In the beginning was only soft foam’
Polyurethane’s ability to offer customised materials, in this case for flexible foam, was also a strong theme in a presentation from Italian flexible foam group Olmo Guiseppe SpA, made by Dr Stefano Cevenini, export sales manager, and Dr Hannes Neukirch, head of soft foam production.
Starting with the resonant title ‘In the beginning was only soft foam,’ Neukirch went on to say that annual production of flexible foam in 1954 was 100 tonnes and rose to 100 kt over the next decade. In Western Europe, production rose steadily from about 250 ktpa in 1970 to 750 ktpa in 1990.
In the last decade foam production has seen “a bit of stagnation,” levelling out from 2005 onwards at about 1000 ktpa, according to Olmo.
Neukirch said that the 60 years of industrial flexible foam production has seen “remarkable progress.” He noted developments such as the change from polyester to polyether polyols giving comfortable and durable foams (late 1950s), and later of reactive polyether polyols, giving high-resilience foam in the 1970s.
Next came development of CMHR (combustion-modified high resilience) foam, and more recently viscoelastic/hypersoft types and use of NOPs (natural oil polyols).
Olmo’s foams mirror these developments, Neukirch said. The group started with just three types, and now the diversity of its product covers over 100 foam types and different colours/block sizes.
Neukirch said the first foam blocks made “looked like Italian cake,” and resulted in a lot of cut waste: also properties were inconsistent across the blocks. Some producers reportedly sold the top half of a block as one type and the bottom as another. Now blocks are much squarer and much more consistent, said Neukirch.
In terms of blowing agents development, ozone depletion potential is now down to zero, but greenhouse gas emission is now also an issue. Flexible foam producers changed to CO2, with two processes, water-blown with no external BAs, and blown by using CO2.
Olmo sees a major trend towards customised products, specially tailored for users, such as modified poly-functional foam for thermal regulation in comfort uses, and laminated foam which is UV stable.
A second trend is towards environmentally friendly production with customers wanting less waste.
Efficient production is the aim, minimising foam waste by producing blocks of consistent density.
A particular challenge is to make lighter foams with no effect on mechanical properties, Neukirch said.
The danger here is that the consumer will find the product does not meet his expectation any more.
Some very low density foam mattresses were sold in Italy, which made consumers feel PU foam was no good for mattresses and it took a long time to overturn this idea, Neukirch said.
Polyurethanes producers have resource conservation as a top priority, with NOPs being used to a certain extent. The work on polyols made using CO2, by Bayer MaterialScience, is of much interest, for example, he added.
Other trends are towards more recycling, and to produce lower emission foams, using appropriate catalysts and stabilisers. “Over the last years a lot has changed in this sector,” Neukirch commented.
