report by Liz White, editor
Replacing some proportion of the traditional petrochemically-derived polyols used in polyurethane formulations has been one of the major trends of the past decade or so, as companies jockey for the 'most green' supplier trophy.
Ford Motor Co. in the US, for example, is sending out a clear message here, that its use of natural oil polyols (NOPs) is widening. In fact Ford has just announced that it is now using higher levels of soya polyols in headrest foam, of up to 25 percent (see box).
Foam makers UTI spoke to recently, however, noted wide variation in the extent of use of such materials by original equipment manufacturers, especially in Europe.
"Everybody is doing it," said Philippe Motte, polyurethane foams expertise manager at French vehicle seat maker Faurecia. "Everybody has developed a solution. We have worked with PSA for instance. They've even put it in their spec."
Motte added that PSA has a specification for a minimum of 6 percent by weight of bio-mass for foam.
But the Faurecia expert also noted that there is a big debate within Europe about carbon dioxide balance. "If you have to import your product from across the ocean – your soya from the US maybe the CO2 balance is not in favour of bio-mass.” But if you source materials from France, “then it works,” he added.
For foam the choice is bio-polyol, “but the spec is bio-mass,” Motte said, in a 16 Aug telephone interview. All seats from PSA have this specification, according to Motte. He deosnt know if PSA will continue this for future models and noted that “They pay for it also—it is more expensive.”
Dr Bernd Welzel, managing director of Fehrer AG, one of the two major independent seat foam makers in Europe, said his customers, which are largely German OEMs – higher prices for NOPs means “no-one wants to have the green materials.”
Welzel said, “We have several times made the proposal to our customers to use the green polyols but as soon as we say they are more expensive the discussion stops.
In North America, the situation is different, Welzel said because of the massive production of soya beans, and influential lobby. There soya polyols are at least the same price as that of hydrocarbon-based polyols or cheaper, he added, speaking 3 Aug by telephone from Fehrer’s Kitzingen, Germany headquarters.
Welzel observed, as did other commentators, that, “from a technical perspective this has been shown to be perfectly feasible. It’s not a technical discussion, it’s a financial one.”
“If it is cheaper we can do it. We have done the trials and shown the realistic ability to use these polyols.”
At Proseat Group, Europe’s other independent seat foam maker, managing director Raphael Thienpoint said foamers are a bit uncertain what the market wants in bio-materials. ”It is the different from OEM to OEM, and when you see the price difference, and the high pressure on performance…”
Thienpoint’s conclusion is that “things that are technically possible are one thing; things that the market will pay for are another.”
At Huntsman Polyurethanes, Andy Walton, automotive platform manger EMEAI, also commented on the higher costs of NOPs, adding that there is also, “degradation of properties as you put more bio-polyol.”
Walton also noted other risks which makes life difficult for suppliers to the automotive business: the possibility of more emissions, depending on the oil used.
"I don't think if you look at the German OEMs it [use of bio-polyols] is a top priority, but the French ones are interested," as they are also in recycling and use of recycled materials or use recyclable materials, Walton said, speaking 8 Aug by phone from Brussels.
Meanwhile. OEMs in the US have a desire to market the 'green foam' aspect globally, Walton said. He referred to Ford as having seen some success in US with use of bio-polyols in seat foam, and said Ford is also trying to see what can be done with bio-polyols in other regions.
North America is different
As mentioned earlier, the US has another take on use of bio-polyols, with Ford amongst the leaders in exploiting its use of NOPs in foam as a strong marketing tool.
At Canadian foamer Woodbridge, the aim is for extensive use of bio-mass in many automotive interior parts. Dr Hamdy Khalil, global R&D director at Woodbridge explains, "It is a fallacy to say PU technology has reached maturity, and what makes it wrong, what makes it fascinating is the introduction of materials of bio-mass origin."
The Canadian company no longer refers to "bio-polyols, canola, soya bean and so on," but instead uses the bio-mass terminology, Khalil said.
Woodbridge is using bio-mass to create materials "that we can include in our chemistry," for renewable and sustainable products, he said.
"This is a real push in North America - and very different to Europe," Khalil commented, in a 2 Aug telephone interview from Woodbridge's Ontario site.
Bio-mass could come from municipal solid waste, and many other sources, he added.
Woodbridge is "very active in generation of bio-mass that we can use as active ingredients in our materials," he said, stressing that these are not fillers - where addition would result in poorer performance.
Khalil added that Europe often raises moral reasons for not using NOPs, as some say the route takes food off the tables of the poor. But he said, this is not the case in the US, where there is an abundance of certain types of natural oils.
Emissions affected by many factors Huntsman's Walton noted that emissions from foam may be affected by addition of NOPs, and OEMs already specify very low emissions, low vocs (volatile organic content).
Motte of Faurecia pointed out that so far there are no low-VOC formulations based on TOI (toluene diisocyanate)." Nevertheless, "everybody is working on developing TDl-low VOC; sooner or later it will come," he added.
"Basically when you are using a reactive catalyst to get low vocs. [TDI] gives weak humid ageing properties. With MDI (methylene diphenyl diisocyanate), indirectly, we have better properties," Motte said. "It's a problem when you are using TOI. You are limited in terms of humid ageing."
Walton made the same point: European OEMs specify low emissions which are probably easier to get with MDI, with good properties, than they are with TOI.
In general, each OEM has a total voc target and also specific vocs they individually want to cut, Walton said. "But to get no voc would be pretty difficult because a lot come from catalysts," he added. And while foamers can use low-emission catalysts, they may then need other additives to get the right properties, which may in turn lead to other vocs, Walton noted.
Khalil at Woodbridge pointed out that the effort to cut emissions is a collaborative one between catalyst and surfactant suppliers and the foam manufacturers.
The aim is to design the best catalyst and surfactant combination that doesn't release undesirable materials, he said.
Collaboration is a must because it's not really easy to replace traditional catalysts, he added. "In my opinion this is an evergreen topic," Khalil said.
While European observers such as Welzel said OEMs in the EU have little interest in recycling, Khalil notes a resurgence of interest from the OEMs in recycling. Across all platforms, OEMs are demanding some recycled content in auto parts, Khalil said. Both Ford and Woodbridge have just launched automotive products containing recycled tyre rubber.
A lot of people are now revisiting glycolysis Khalil said adding that there is plenty of source material here as people are still using rebond foam for carpet backing.
Infichem llc is making recycled polyols by a special glycolysis process, and this is now on the market, and work with seat maker Magna and Woodbridge is under way, he added.
Lighter parts being made
Lightweighting in automotive is a trend that affects every part of the car and is also where reinforced plastics parts are being developed, commented Welzel of Fehrer.
He listed the body-in-white (BIW, the bare vehicle structure before painting), seats and structure, and interior parts as all areas where use of composites with glass and carbon fibre is being developed
Fehrer has been making interior parts for 30 years using rigid reinforced PU, but the difference now, said Welzel, is that these products are being used for structural parts, for example partitions and seat structures, where other companies are using EPP (expanded polypropylene).
But fibre- reinforced parts have the problem of "higher part price in comparison to steel," said Welzel. "That is a fact and will be for decades. So the important question is total project cost, taking tools and other aspects into consideration, he said. For example, Welzel noted, one plastic part can replace four welded metal ones. "So you have to take the bigger picture."
Now the automotive industry is taking these big steps with the BMW mega-city-vehicle, where the complete BIW is made out of carbon fibre - "that's a 100- percent change," Welzel said.
"I am convinced that change is too big a step, that in the long term we will see a mix of different materials inside the car… But it's a good experiment to see what happens when everything changes," the Fehrer boss commented.
Use of EPP in seat structures for lighter weight is becoming common.
"Everybody is using EPP, not only Lear, and especially on the rear bench. But people are also trying to replace EPP with urethane rigid foam, because EPP is quite expensive," said Motte of Faurecia.
In EPP, there are only two or three players, "so if you are not integrated in EPP, you have to buy the moulds and they are more expensive than for urethanes, as well as the raw material itself being more expensive," the Faurecia expert explained.
EPP is used to replace part of the metal seat structure, said Motte. "A lot of rear benches have a metal frame which can be replaced by EPP parts, or reinforced rigid PU," he added.
At Proseat, Thienpont said, "We have done a development with Faurecia for a low-weight seat,where in fact the shell is made of plastic - EPP." Thienpont explained that this is, "the most complex EPP part I have ever seen."
These kind of structures are weight-saving approaches, as is EPP in anti-submarine ramps in the rear of the seats, where it is taking more and more a role.
"These are structures where we can contribute, but cannot take an active role because seat design is not our business. We do not have the knowledge of the total seat function that is more related to the Tier ls," Thienpont added.
Faurecia has a lightweight seat design under development which Motte said has a thermoplastic PU seat frame, with thin, light seat pads. But he feels this is partly a marketing tool, and will remain in niche applications For long distances, such seats have questionable comfort, he indicated.
Discussing foam replacement by other materials in seats, Motte said foam remains the best compromise so far between weight and properties. Foam is made in one operation, he pointed out. "If you add other materials, gel silicone, EPP, or polyester, this needs an additional operation, which adds cost, Motte said, noting that, "The major cost of the seat is from the labour costs. Each time you add different components, it's a different operation."
The average weight of foam in car seats is between 10 kg and 14 kg out of a total seat weight of about 40 kg, Motte said.
With a metal frame there is more that can be done to reduce weight. With foam, "you can reduce volume, have thinner seats, but you can never cut down by so percent." he added.
Welzel thinks it's good that there are always people looking at other materials for seats. Fehrer itself puts some effort into this, but "honestly speaking, until now we haven't seen a material that is comparable in the specification to today's polyurethane. And for automotive, as I said, you always have to have a seven-year programme," he added.