Polyurethane products were invented in the 1940s after Otto Bayer and his coworkers discovered and patented the chemistry of polyurethanes in 1937. The substance becomes a flexible and very durable material that has to be manufactured to be usable in society and has continuously evolved to be used in a wide variety of items. Polyurethane is used to create rubber, metal and wood products. It is also used in paint, cotton, and other fabrics. Based on its structure and uses, Polyurethane can conform to a variety of items. It can be found in foams both rigid and flexible, chemical-resistant varnishes and coatings, special sealants, rubber adhesives and even fiberglass.
The basis of the Polyurethane substance is categorized as a polymer. A polymer is a molecule that consists of several smaller units called monomers. Polyurethanes are manufactured by mixing two types of chemical compounds of Polyols and Polymeric Isocyanates, along with other additives to create a chemical reaction. The basic material has several fairly indestructible variations that can be altered and can be presented in the forms of liquid, foam, or solid each providing its own limitations and advantages.
Polyurethane molded products typically consist of a resin base, some type of curative, and a dye or pigment colorant additive. Most manufacturers use high tech equipment that first mix the ingredients into a comparable liquid which is then heated and molded to create the finished product. Because Polyurethane is so pliable, the machines used to produce the product consist of chemical tanks that keep the raw materials at a certain high temperature for optimum processing. The tanks are linked to complex mixing chambers where the polyol and isocyanates are mixed together and the mixture is poured in to specified mold cavities for their desired shapes.
The typical methods used to mix, mold, and creates polyurethane products are:
Compression Molding: Polyurethane in liquid form is poured into a mold and placed in a compression press. The heat allows the liquid to thicken and the pressure from the press creates the completed molding process.
Open Cast Molding: In this process the liquid form of polyurethane is poured into an open mold. The mold is then placed into an oven.
Spin Casting: This process requires a spinning mold in which the liquid polyurethane is poured into. This process remove all air trapped inside the chemical as it is being poured.
Low Pressure Injection Molding: This process requires the liquid Polyurethane to be injected into a closed mold. The mold is designed with openings to allow air to slowly leak out.
Polyurethanes are best known to the general public in the form of what is called flexible foam. These polyurethane foams are manufactured in the forms of mattresses, upholstery, and other chemical resistant packaging. Again, it can conform to almost any type of structure and also comes in forms that can be used in insulation for water heaters and buildings. This substance is continuously adapting to be used in our current technology.
