FREQUENTLY ASKED QUESTIONS
Polyurethane foam is an article. This view was supported in ECHA’s Guidance on requirements for substances in articles from 2011, which in its page 50 states that: “in the conversion unit, the structure and design of the polymer compoulds is changed. In the resulting material, the design and structure is kept during further processing. For the polymer sector, this means that processes including for example, but not limited to, pipe extrusion, film blowing, blow moulding, sheet forming, rotomoulding, foaming, compression moulding, fibre spinning or tape slitting calendaring, coating or injection moulding mark the ‘red line’ between mixture and article”.
Foam gotten by mechanical recycling is called bonded foam. Main applications bonded foam is used for is in packaging, insulation, flooring underlay, sports mats and cow mats, among others.
If polyurethane foam is chemically recycled, due to the process of degradation the final products are its constituent raw materials, which can be then used in new foam formulations.
Composite foams or rebounded foams are foams produced from production waste (trim foam) that is “glued” together with diisocyanates. Composite foams are used for example as carpet underlay, for packaging, shoes insoles, or for sport floors.
The most common flexible polyurethane foam families are: Standard Ether Foams (E), High-Resilience Foams (HR) and Visco-Elastic Foams (VE). In the UK market there are also Combustion Modified Ether Foams (CME), Combustion Modified High-Resilience Foams (CMHR) and Combustion Modified Visco-Elastic Foams (CMVE). The difference between them lies in different physical and mechanical properties; namely in density, hardness, tensile strength, viscosity, etc…
Additives are substances that can be added to the mixture of polyols and diisocyanates at the time of foam production to be present in the foam and/or to provide it with specific properties. They for example help controlling cell structures, cell opening, odor formation or flame resistance. They can also be added for aesthetic reasons, with pigments for example allowing for foam of any colour to be produced.
Natural Oil Polyol (NOP) polyurethane foams are produced by using in part polyols from renewable sources such as soybean, castor, sunflower, rapeseed oil or a mix thereof. Apart from that, they are manufactured in the same way as traditional foams.
Spontaneous ignition of polyurethane foam is not possible under normal operating temperatures. However, being produced from crude oil derivatives, polyurethane foam does have high energy content and can burn when submitted to high heat or a direct flame. Depending on the specifications of customers or national regulations, flame retardants may thus need to be added as additives, for example for upholstered seating in public places such as theatres or cinemas which need to comply with strict fire regulations.
Fogging is mentioned in automotive applications. It refers to the deposition of volatile compounds coming from interior trim materials on the windscreen and rear window of the car. This notably happens under the influence of high temperatures in the passenger compartment. Low fogging foams are designed to reduce this phenomenon.
Flame lamination is used to produce laminates of foam and fabrics by passing the polyurethane foam over an open flame. The heat melts the upper surface of the foam. This melted layer acts as glue bonding the foam and the fabric.
Flame laminated foams are typically used in the automotive industry for seat covers, headliners and door panels, as well as in the shoe and clothing industry.
Fresh polyurethane foam comes with an odour that can be compared to the smell of fresh paint. This odour disappears within days and usually well before end-products are being placed on the market. Controlling odour is a matter of discipline in raw materials sourcing, production and quality control by the foam manufacturer.