BASF's polyamide 610, on the market since the K show in 2007, is being joined by additional grades. Four new glass fiber-reinforced materials now complement the unreinforced grade Ultramid S3K Balance. They are designated Ultramid S3EG6 Balance, Ultramid S3WG6 and S3WG7 Balance and Ultramid A3HG6 Balance. Their glass fiber contents are 30 (G6) and 35 (G7) percent and they will be available in sample quantities in Europe as of September.
It is known that Ultramid S Balance differs from conventional polyamide 6 (PA 6) and 66 (PA 66) by having a lower density and reduced moisture uptake. In-depth comparisons with other special polyamides available on the market indicate, however, that the material holds much greater potential.
Strong in comparison: resistant to hydrolysis and stress cracking
Two properties in particular make this material a worthy competitor to other long-chain high-performance polyamides such as PA 612 or PA 12: its hydrolysis resistance, i.e. its great resistance to hot water and steam as well as its resistance to environmental stress cracking when exposed to aggressive chemicals. Above all, its resistance to calcium chloride, which is used in Asia and Russia as road salt, and zinc chloride, which can form on car bodies, should be pointed out. Compared to PA 66, the material has not only greater dimensional stability, but also exhibits only a slight difference in mechanical properties between the dry and conditioned states. It is stronger, stiffer and has a higher heat deflection temperature than PA 12.
The three new grades in the Ultramid S Balance line are thus especially well-suited for overmolding of metal and electronic components that come into contact with aggressive fluids. They are also of interest for housings and transmission components where dimensional stability is a major factor. Connectors, tubing and reservoirs in coolant circuits that must satisfy demanding requirements for hydrolysis resistance represent an additional field of application. The material has already demonstrated its performance capability in wheel speed sensors that are exposed to water spray and can be attacked by road salt.
Additional new materials
Use of PA 610 as the base polymer permits other interesting materials in addition to the Ultramid S Balance series: blended with PA 66, it yields the equally new grade Ultramid A3HG6 Balance. This product is characterized by a property profile that lies between that of PA 66 and Ultramid S Balance, while retaining its high resistance to environmental stress cracking and exhibiting in addition very good resistance to hot oil. This makes it a suitable candidate for oil pans and oil filter housings as well as for radiator end caps, wheel speed sensors and other components subject to contact with aggressive water spray - in other words, for applications that do not have to satisfy the most demanding requirements for resistance to hot water, but must be strong, stiff and dimensionally stable at elevated temperatures. It is possible in this way to develop finely tuned specialties in terms of price and performance that allow customers to satisfy their specific needs.
Renewable resources included
One of the raw materials for production of Ultramid S Balance and Ultramid A Balance is sebacic acid, which is derived from castor oil. Thus, over 60 percent of the base polymer for the product family comes from renewable resources. For customers who value bio-based materials, this resin is of interest for more than just its performance characteristics. Whenever possible and practical, BASF also offers materials based on renewable resources. As a rule, however, the company recommends that an Eco-Efficiency Analysis be carried out before using bio-based materials as an alternative to conventional plastics, since use of a bio-based product alone does not guarantee an eco-efficient profile in the end product.
Surprising result of Eco-Efficiency Analysis
Shortly after introducing the very first Ultramid S Balance grade, BASF conducted an Eco-Efficiency Analysis for a typical automotive application. Two automobile intake manifolds with a service life of 200,000 kilometers were compared. The Eco-Efficiency Analysis included, as always, all ecological and economical criteria regarding production, application and disposal of the product in order to have a complete picture of the environmental impact and cost aspects of the alternatives being considered. The glass fiber-reinforced Ultramid S Balance had slightly less environmental impact, but considerably higher costs than the classic PA 6. For an air intake manifold, the standard PA 6 resin thus represents the more ecologically efficient solution.
Costs? Performance? Raw material source?
Ultramid S Balance is an example of how the discussion about performance, costs and sustainability of a modern plastic can be conducted. In the case being considered, the fact that the sebacic acid used for production of PA 610 is derived from a renewable resource provides a slight ecological benefit, but contrary to expectations this benefit is based not on the plant origin of the carbon, but rather largely on the lower specific weight of the Ultramid S Balance. The considerably higher additional costs associated with the production plants for this relatively low-volume plastic, however, outweigh the slight ecological benefit from an economic standpoint. A further contributing factor is the volatility of the sebacic acid price, which is typical for renewable resources. It results from the occasionally occurring crop failures and the resultant fluctuations in availability. The plastic is thus of interest today not because of its renewable resource base, but for its outstanding performance profile, which positions it distinctly above PA 6 and PA 66 and raises it to a level comparable to PA 612 and PA 12 when it comes to certain central properties.
Against the backdrop of highly charged discussions about costs, environmental factors as well as performance requirements, numerous new products will be developed that allow the variety of plastics to continue growing, and in view of this wide assortment the customer must carefully consider where his preferences lie.