The engine splutters, and thick, black smoke billows up from the hood: Every 13 minutes, someone in Germany has to pull over to the side of the road in this situation. For many, it is a moment of worry. A minor technical error, such as a short circuit in the wiring harness or leaking oil that catches fire when it comes into contact with hot car parts, is enough to start a fire. However, depending on the intensity, it can still take several minutes for the entire car to go up in flames if the fire continues to spread. This usually gives drivers and passengers enough time to get themselves to safety – all thanks to chemical flame retardants in the materials. These flame retardants inhibit or delay combustion processes. They are found in plastics such as polyurethanes, which carmakers use to upholster seats, roof linings, rear shelves or side trim panels. With its products Disflamoll® and Levagard®, LANXESS is a reliable partner for these needs.

BIDING FOR TIME

Evidence of this expertise can be found in Leverkusen, Germany, in the middle of CHEMPARK, one of Europe’s largest chemical parks. Here is where CURRENTA tests the effectiveness of LANXESS fire retardants under controlled supervision at its fire technology laboratory. “Materials in cars and buses must meet certain fire technology standards,” says Julian Bulk, Laboratory Supervisor at CURRENTA Fire Technology. As an example, he refers to the horizontal burning rate – a standard (FMVSS 302) that is used worldwide for the interiors of cars and buses. “The point of this is to ensure that a car seat, for example, does not explode into flames.” In concrete terms, this means that if the plastic in a seat catches fire, the blaze must not spread horizontally at a rate faster than 102 millimeters per minute. A fire here can be sparked by the flame of a lighter or match, or even the burning ash of a cigarette. Bulk: “This gives drivers and passengers enough time to get out of the vehicle.”

AT THE FIRE TECHNOLOGY LAB

Julian Bulk knows from experience of the difference fire retardants in plastic can make. Using a wide range of standardized test methods, he and his 18 colleagues review the fire behavior of plastics every day. “The plastics being tested are normally protected with flame retardants to fulfill the requirements,” he explains. If they are not, they usually do not pass the test. A comparison test supports his findings. First, tester Mahi Hakiki places a sheet of plastic made of flexible polyurethane foam the size of a piece of paper, folded lengthwise, horizontally into a small test chamber simulating the interior of a vehicle. The plastic has not been treated with a flame retardant. Before the test starts, Hakiki marks both ends of the sheet with a white stripe to help him determine the burning rate later on. Then Hakiki lights a flame and places it underneath the plastic sheet to simulate a source of ignition. The plastic sample catches fire. After 15 seconds, Mahi Hakiki turns off the burner. He watches the fire with a concentrated expression on his face. Once the flame reaches the first mark on the plastic strip, he starts recording the time. The flame continues moving, while burned plastic drips onto a bed of gravel. Just as the fire reaches the second mark, Hakiki stops the time. The computer generates the result: 106 millimeters per minute. The sample has failed.
 
LANXESS MAKES THE DIFFERENCE

Then it is time to test the plastic sheet made of flexible polyurethane foam with the LANXESS fire retardant Levagard®. The test is identical. Tester Mahi Hakiki once again lights a flame. The new plastic sheet also catches fire. After 15 seconds, Hakiki turns off the burner. The results are clear: The fire goes out as soon as the flame is switched off – long before reaching the first mark. “Self-extinguishing” is the term Heiko Tebbe, Senior Manager of Application Technology at the LANXESS business unit Rhein Chemie Additives, uses to describe the effect of the fire retardant. He explains: “During the burning process, Levagard® forms a sort of protective layer of carbon on the material. We call this process ‘carbonization.’ It prevents oxygen and heat from entering the lower layers of the material and keeps the fire from spreading further.” This effect has the potential save lives.
 
SAFETY FIRST

It is essential to extinguish a fire as quickly as possible, regardless of whether it was caused by a technical defect, an accident or just a brief lapse in judgment by the driver or one of the passengers. But because this is not always possible, automakers today are increasingly turning to the “self-extinguishing effect” of Disflamoll® and Levagard® fire retardants – not least because the effect goes well beyond the minimum horizontal burning rate requirements. For Heiko Tebbe, the reason is clear: “There’s no cutting corners when it comes to people’s safety.”