The Benefits of Polyurethane Foam
Polyurethane foams are used in a variety of consumer and commercial products. You can find it behind upholstery fabrics in furniture and as carpet underlay, and in car headliners and bumpers to achieve greater automobile “mileage.”
There are six main components in a polyurethane formulation: polyols, diisocyanates, blowing agents, surfactants, catalysts and curatives (chain extenders and cross-linkers). Creating foams requires achieving a delicate balance between expansion and gelling, known as the “blooming” process.
Durability
Polyurethane foam is incredibly durable. It can bend tens of thousands of times without breaking. It also resists abrasion and moisture. It’s often used in the backs of chairs to protect the frame from wear and tear. It’s also found in many household products, from pillows to mattress toppers. Rigid polyurethane foam is often used as insulation, helping to save energy and reduce carbon emissions by keeping homes warm in winter and cool in summer.
The durability of polyurethane foam is due in part to its cellular structure. Millions of small gas bubbles are arranged in uniform designs throughout the material, creating an extremely strong and flexible structure. The density of the foam determines its rigidity, with softer foams used for mattresses and tougher foams for long-lasting furniture.
There are four different types of polyurethane foam, each with very distinct physical properties. All are created by varying a basic addition polymerization reaction of a diol or polyol and a diisocyanate. Additives such as surfactants, blowing agents and curing agents can be added to control the reaction and impart specific properties for the intended use.
Blowing agents generate the gas that creates the cellular structure of the foam. Historically, CFC-11 (trichlorofluoromethane) was the primary blowing agent in urethane manufacturing. However, it was banned by the Montreal Protocol in 1987 for its tendency to deplete the Polyurethane Foam ozone layer. Today, blowing agents are typically water, pentane, methylene chloride hydrocarbons, or halogen-free azeotrope blends with zero ozone depletion potential.
Lightweight
Polyurethane foam is extremely lightweight, which saves on shipping costs and allows designers to create more compact components. It also provides a level of flexibility that makes it possible to mold into unique shapes. For example, flexible polyurethane foam is used as cushioning in upholstered furniture, bedding and carpet underlay. It also helps make boats lighter and more comfortable. In addition, it is a key ingredient in many sports equipment, such as kayaks and surfboards.
Polyurethane can be produced as rigid foam or as flexible foam, depending on the product’s design and application. Rigid foam can be created with a variety of materials to meet specific product requirements, including polystyrene, polyethylene or polypropylene. In addition, it can be reinforced with fiberglass or other materials to improve tensile strength, elongation at break, and tear resistance.
Rigid polyurethane can be molded using reaction injection molding (RIM) processes, which allow for thick- and thin-walled parts with encapsulated cores. The process also enables the creation of parts that would be difficult or impossible to produce through traditional injection molding processes. RIM is particularly useful for manufacturing car bumpers, computer and telecommunication equipment enclosures and furniture.
In order to produce PU foam, a hot liquid polymer system is mixed with a blowing agent. This mixture is then poured onto a conveyor and forced through a series of rollers coated with waxed paper. The blowing agent generates gas, which forms the foam’s cellular structure. A variety of additives can be added to the mixture, such as cross-linking agents, chain-extending agents, blowing agents, surfactants, fillers, plasticisers and pigments. These additives can influence various properties, such as cell formation, hardness and colour.
Thermal Insulation
Foams made from polyurethane offer exceptional thermal insulation. They are also strong and durable, meaning they resist damage from abrasions and pressure. These properties mean that they can be used in a range of different applications and are an excellent choice for insulating buildings, including new and existing homes.
Polyurethane foam insulation can be sprayed on or injected into a Polyurethane Foam cavity using spray or injection machines. These machines work by mixing and atomizing the liquid polyurethane foam to create a fine spray. It is then blown onto the surface using a high-pressure spray gun. It will stick to itself, most metals and wood, as well as other materials. The resulting spray can then be shaped and moulded to fit the desired space.
Rigid polyurethane foam is commonly used in the construction industry as it is a good thermal insulator, offering high R-value and U-factor. It is CFC-free, and its closed-cell structure makes it resistant to moisture and other elements.
Polyurethane foam is produced by combining two chemicals, known as a polymer and a surfactant. The polymer is formed by a chemical reaction between polyol, a type of complex alcohol, and diisocyanate, a petroleum byproduct that reacts with the hydroxyl groups in the polyol to produce urethane. The surfactant, which is a mixture of water and other substances, helps to stabilize the long-chain molecules and make them easier to handle.
Comfort
Foams are a critical component of many of our everyday comforts, from the cushions on our furniture to the mattresses in our homes. Polyurethane foam is a versatile and lightweight material that has many benefits for different applications.
Rigid polyurethane foam is used for insulation in homes and buildings, reducing heating and cooling costs. It also protects against moisture and mold. It is a very versatile material that lasts for over half a century and requires very little maintenance.
Flexible polyurethane foam can be formulated with a variety of performance characteristics, from the softness needed for upholstered furniture to the shock absorption required for packaging and the abrasion resistance demanded by carpet cushion. The foam industry uses specialized tests and terminology to precisely specify these properties for each type of product.
Most people are familiar with the low-density PU foam commonly used in sofa cushions and cheap “egg crate” mattress toppers. This type of foam contains the flame retardant polybrominated diphenyl ethers (PBDE), which have been linked to decreased sleep quality and increased rates of breast cancer, thyroid disease, and obesity in children. Research continues to replace PBDEs with safer alternatives.
