Seating Polyurethane

Section through Renault 5 seats, polyurethane foam produced in situ (courtesy ICI Polyurethanes). 

For passenger car seating about 90% is made by the molded foam process. The transportation market has expedenced a decline since 1979 due to decreased automotive production and also because U.S. cars have been downsized, resulting in the use of less polyurethane foam per car. 

Polyurethane foams are widely used. Rigid foams, for example, are used in cavity wall insulation in buildings, while flexible foams have, until recently, been used in soft furnishing for domestic use. They continue to be used in car seating. In addition to foams another major use of polyurethanes is in surface coatings. A variety of polyurethane-based polymers, some of considerable complexity, are used for this purpose, but all share the common desirable features of toughness, flexibility, and abrasion resistance. 

Chicago, 11., 26th-29th Sept. 1995, p.270-4. 43C6 TERTIARY RECYCLING OF WASTE POLYURETHANE CAR SEAT FOAM Tatsumoto K Elam C C Looker M J Evans R J US,National Renewable Energy Laboratory (SPl,Polyurethane Div.)... 

Most automobile and furniture seating, foam mattresses, carpet underlay-ment, and other similar products are made from polyurethanes based on polypropylene glycol (PPG). PPG is the preferred raw material for these type of polymers because of the wide variation of possible properties of the end product and the relatively low cost. 

Some of the key factors that lead us to select polyurethane foam for upholstery are its durability, resilience, and controllable hardness (or softness, depending on your point of view). Vibration dampening and shock absorbance are important attributes in automobile and public transportation seating. Open cell foams are preferred for these applications because they allow for air and moisture transport, which improve the comfort of passengers who may occupy a seat continuously for several hours. This inherent breathability is also a valuable attribute in mattresses. Shock absorbance plays a key role in selecting flexible polyurethane foams for the packaging of fragile items. 

Rigid integral skin polyurethane foams are used to make seat pans, office equipment housings, tanning beds, water skis, and surfboards, all of which must be light and stiff. 

What properties of polyurethanes make them an excellent choice for foamed seat cushions ... 

Polyurethane foams are lighter than foam rubber and have displaced many of its applications, such as in bedding, cushions, car seats, armrests, and crash pads. Laminates are used widely in clothing as padding. 

One of the more advertized advances in commercial offering of polyurethanes from renewable resources was the introduction of soy-based polyol in the 2008 Ford Mustang [180, 181]. Ford partnered with Lear Corp. to produce automotive seats containing up to 40% soy-based polyol. This was hailed as a throw-back to the early days of Ford Motor Company, when Henry Ford incorporated as much as 60 pounds of soybeans into paint components and molded body parts for the Model T. 

However, this is an oversimplification since other reactions are also usually involved [Backus, 1977 Backus et al., 1988 Occhiello and Corti, 2003]. Foamed products such as seat cushions and bedding are the largest applications of polyurethanes. Water is often deliberately added in the production of flexible polyurethane foams. Isocyanate groups react with water to form urea linkages in the polymer chain with the evolution of carbon dioxide. The... 

In the world of polyurethanes, standard methods describe the properties of the materials. While the conventional methods of analysis are necessary for compliance with the physical design of a system, our task must include chemical tests, and they must be developed on an ad hoc basis. Nevertheless, conventional methods for analyzing a polyurethane are very helpful and are reviewed here. Our focus will be on the effects of the polyurethane chemistry on fluids with which it comes into contact. Because this is different from the typical use pattern, some of the standard methods used to produce seat cushions, for example, will not apply. We will discuss several methods but not in the traditional order. 

Brominated flame retardants (BFRs) are added to many consumer and commercial products to prevent these products from burning even if they have been exposed to a spark or a smoldering cigarette. BFRs are added to polyurethane foam that is used in furniture found in most homes and offices to commercial fabrics used in, for example, auditorium seating and to carpeting. BFRs certainly save lives by preventing large fires, but some of these chemicals have become environmentally ubiquitous. 

Aromatic hydrocarbons need to be used with careful consideration. At ambient temperatures, they can cause swelling, and at higher temperatures there is a slow breakdown. It has been found that in uses up to 40 or 50°C, polyurethane can be used in petroleum pump valve seats. 

Flexible foam. This is made by mixing long trifunctional polyol with isocyanate to form the polyurethane, and adding a little excess isocyanate and water to the reaction to produce carbon dioxide which produces the foam. The largest use is in furniture, with smaller amounts in auto seating, mattresses, rug underlay, textiles, and packaging. 

In the early 1980 s a neoprene-type foam (VONAR) made by Du Pont was developed specifically for use as a comfort cushioning material for critical applications where low flammabUity was required, such as in transport aircraft seat cushions. This material is designed for use over flame-retardant polymethane foam and is believed to provide 50 seconds more of evacuation time in the event of a post-crash fire. VONAR has a density of 10.66 Ib/ft , compared to 7-8 Ib/ft for standard neoprene foam, and 1.2-2 Ib/ft for polyurethane foam (5). 

MIL-S-27332B(USAF) Seat Cushion Insert, Polyurethane Foam, Plastic, General Specification for, 26 October 1983, 10 pp (FSC 1660) (82)... 

TDI (10a and 10b) is prepared from o-nitrotoluene, which is first nitrated to afford 1,4- and 1,5- dinitro isomers. These products are hydrogenated to the corresponding diamines, at 74 °C, over a palladium-on-carbon catalyst. This is the only major use of toluene diamines. On phosgenation, using chlorobenzene as solvent, at around 52 °C, the amines afford the diisocyanates. The TDI is used in the manufacture of flexible foams (upholstery, bedding, seat cushions, etc.), paints, surface coatings, elastomers and adhesives. 1,5-Diaminonaphthalene (13) is converted into naphthalene-1,5-diisocyanate (14) (Scheme 5), used in specialty polyurethanes. 

Di-n-butyltin catalysts are being used in the preparation of polyurethane foams. Most polyurethane foams utilize aromatic isocyanates such as toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI) as the isocyanate, and a polyester or polyether polyols as the coreactant. Tertiary amine catalysts are used to accelerate the reaction with water and formation of the carbon dioxide blowing agent. To achieve a controlled rate of reaction with the polyol, an organotin catalyst can be used. Polyurethane foams are not only applied in place, but are also cast in a factory as slabstocks. These foam slabs are then cut for use in car seats, mattresses, or home furnishings. DBTDL is an excellent catalyst in high resiliency slabstock foams. DBTDL shows an excellent reaction profile for this application replacement for DBTDL in such an end-use is difficult and requires a substantial reformulation of the foam. 

Polyurethane PUR Good NVH dampening, good elasticity, low heat conductivity Seat upholstery, jounce bumpers, dash and roof padding, exterior elements... 

The diisocyanates are reacted with diols to produce polyurethanes that end up in consumer products, such as seat cushions, mattresses, insulation, car bumpers, swim suits, floor coatings, paints, and adhesives.12 The aromatic diisocyanates are cheaper, but yield less light-stable polymers than the aliphatic ones. 

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