What is Polyurethane?
Polyurethane (PU) stands for an important group of products within the big family of polymers or plastics. PU is a generic name for a wide range of foam types.
The structure of PU foam consists of a network of dodecahedron cells which behave as micro-springs. The properties of PU depend on :
- the chemical composition and thickness of the cell walls.
- the volume-solid matter/air ratio.
- the concentration of the cell membranes (air permeability/open cell structure).
PU is used in a large number of strongly diversified applications, such as filler for seats, chairs and seat cushions, mattress centres, car seats, encapsulation of car windows, shoes and textiles, thermal insulation (buildings, industrial installations, refrigerators, etc.), sound insulation, adhesives and paints/coatings, etc.
The great advantage of PU foam is its great flexibility in meeting the various applications and requirements. Polyurethane owns some extremely exceptional material qualities such as: density, elasticity, durability, weight, safety, design and of course its attractive price.
Since PU is mainly used together with other materials, such as textiles, metal, wood and other polymers, it is not always visible in the end products.
Flexible foam – rigid foam - elastomers
Being a leader in its different markets, Recticel manufactures PU foam in various forms, the bulk of PU production being in the form of flexible foam. Flexible foams can be produced in the form of long blocks (slabstock) which are then cut into semi-manufactures (for example, for the furniture industry) or finished goods. Flexible foam is sometimes poured directly into specific moulds. This process (moulded foam) is applied especially in the production of car seat cushions.
Recticel also produces rigid polyurethane foams, which are used primarily for thermal insulation and can be produced in panels ready for use and in large blocks which are then converted into more complex components.
Recticel’s research and development expertise has enabled it to produce PU with new finishes and properties. The Colo-fast® and Colo-fast® Spray products (elastomers), both used so successfully for interior trim in the automotive industry, are clear proof of this.
It is characteristic for polyurethane that the production units in principle have to be located close to their final market. This property is prompted by the high costs incurred in the transportation of bulk products with a relatively light weight over long distances.
Production of polyurethane foam
Three basic raw materials play a key role in the production of polyurethane foam: polyol, isocyanate and water. Agents, such as catalysts and stabilisers, are used to support the chemical process. In addition, further additives can be added to the formula with a view to obtaining specific product properties such as: colour, fire-retardant or anti-static effect, etc.
The petrochemical industry refines 95% of the crude oil it processes into fuels (naphtha and allied products). A wide variety of other chemicals can be distilled in one or more stages from the 5% residue, including polyhydroxy compounds and isocyanates, the main raw materials used in the production of polyurethane.