Flexible polyurethane foam is a polymeric material which is produced by combining two main substances: polyols and diisocyanates, as well as other minor components such as water. When these substances are mixed together, they react almost instantly – creating PU foam. 

It is widely used in applications requiring comfort, support, and durability, such as upholstered furniture and  bedding applications, amongst others. The foam can be produced in various densities and hardness levels, depending on its intended use.

Europe is indeed a big producer of polyurethane foam. There are 174 plants in wider Europe and, of those, 109 plants are in the European Economic Area and the United Kingdom. Their combined production of flexible PU foam blocks in a semi-continuous process called slabstock foaming in 2023 was about 900,000 tonnes.

About 50% of the slabstock foam produced in Europe is used in mattresses, 35% in furniture, 7% in transportation, and the rest in hundreds of other applications.

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”.

Yes, flexible PU foam is recyclable. Various recycling methods are available, including mechanical recycling, where foam is shredded and reused as rebonded foam in carpet underlay or cushioning, and chemical recycling, also called depolymerisation or waste-to-monomer, which breaks the targeted bonds in the foam with the goal of recovery of base raw materials. 

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) or from end-of-life PU applications (such as mattresses) 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…

The main raw materials used to manufacture FPF are polyols, isocyanates, and water, along with additives such as catalysts, surfactants, and flame retardants. Polyols and isocyanates chemically react to form the foam, with water acting as a blowing agent to create its cellular structure.

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.

Yes, flexible polyurethane foam is an entirely safe product in the many diverse applications it is used for. The diisocyanates it is produced from are consumed during the chemical reaction that creates polyurethane. They cannot be released into the air from polyurethane foam.

However, risk assessments have shown that other substances can be released from foam, as volatile organic compounds, depending on the composition and production method that is used.

The European polyurethanes industry has over the years invested heavily on research into such substance emanations from foams. This research uses advanced technologies to measure the substances that may potentially be emitted by polyurethane foams down to the limits of detection, in the part per million (ppm) range.

The results of this research have been used to create our standard for polyurethane foams, CertiPUR, which sets state of the art stringent limits for many substances.