Polyurethane (PUR foam) is a polymer, which is produced by means of polyaddition of diisocyanates and di- or poly-atomic alcohols, giving rise to a urethane bond. The isocyanates react very easily with all compounds containing active hydrogen (e.g. water, alcohols, phenols, thiols, amines, carboxyl acids, etc.) The main growth response is therefore accompanied by a number of side reactions, some of which are used purposefully in the manufacture of certain types of polyurethanes; for example, the release of CO2 (thanks to the reaction of the isocyanate group with water) is important in manufacturing foam polyurethane, as it functions as an expanding agent. PUR foam is a very wide term; it consists of many types and sub-types distinguished according to their parameters, utilization purpose and means of processing. Our company manufactures shaped parts in a discontinuous way of manufacturing - foaming up in forms
Manufacturing polyurethane foam• Basic components for the manufacture - polyol (polyether / polyester)- isocyanate (MDI)• Other components- water- catalysers and stabilizers of the reaction- other substances influencing the special qualities of foams (fire retardants, pigments, anti-oxidants, etc.)
Parameters of PUR foams• volumetric weight kg/m3• resistance against compression kPa/ 40% (or event. 25%, 70%)• resistance against impression N• tensile strength kPa min• ductility %• firmness of tear N/cm• permanent deformation %• porosity ppi, or event. micron• aeration l / min• resistance to flame, classes according to tests • fogging %• hydrophobic quality• hydrophilic quality %• surface resistance Ohm• internal resistance Ohm/m3• and more
Volumetric weight• Definition: Weight per unit of volume.
• Formula: Density (kg/m3) = ----------------------
The main types of PUR foams:
- Integral PUR: Thanks to their typical profile of characteristics, they provide attractive alternatives to traditional materials like wood, metal, thermoplastics and thermosets. The sandwich structure, which provides the shaped parts with high mechanical strength at a relatively low weight, is manufactured in a single working step from one and the same material. The reaction mix is applied in closed forms. At that, a massive edge zone-crust is created in this form, as well as a finely porous foam core. The foam density demonstrates an integral course in the cross-section of the constructional part. This is mostly applicable in the automotive industry (steering wheels, gear lever grabs, head rests, handrails), as well as in other industrial fields like healthcare and the furniture industry (elbow rests, hand rests, rehabilitation units, collars to whirlpools).
- Rigid PUR: Rigid polyurethane foam is a highly reticulous thermosettic plastic material with closed pores with both low and high density-volumetric weight. The low heat conductivity provides this material with excellent heat-insulating qualities. Rigid polyurethane foams provide highly efficient heat-insulating and constructional material utilizable in many fields of human activities.
- Soft PUR: These polyurethane foams are used for the manufacture of products like seat adapting pieces, head rests, head supports and mattresses. Apart from being used as comfortable upholstery in furniture, seats, pillows and mattresses, there are other applications using the further technical qualities of soft foams, like in different fillings, foam seals, noise absorption in the constructional part for vehicle interiors, or high tenacity in the manufacture of air filters. Soft foams may be manufactured as blocks in a continuous and discontinuous way. However, in many applications of soft foams, complex geometry of the shaped part is set, which may be realized via direct manufacture of shaped foams. There are therefore no limits to the variety of shapes, with high comfort at the same time.
Apart from highly elastic upholstery systems, we also offer special systems with improved fire-prevention qualities (DIN 5510-2, UIC 564-2, EN 45 545) or special viscoelastic characteristics. In viscoelastic foams (so-called “lazy” or Memory-foams) with slow return to their original shape, the application of a load provides for optimal distribution of stress and therefore the highest possible comfort in sitting and laying.