Weatherstrip is a sealing component for vehicles made of elastic materials and support rigid structures. It is applied to the door and the body structure of the vehicle or moving assembly to protect the inside of the vehicle from the external environment. It plays a major role in preventing external pollutants such as rain and dust from entering the vehicle inside, and effectively blocks wind noise that may occur during medium/high speed driving, helping the driver to drive comfortably. In general, while driving a vehicle, relative vibration motion due to displacement and time lag constantly occurs in the moving assembly and the body structure of the car body. In particular, when driving on uneven roads and unpaved roads, the range of displacement in this relative motion is greater. As continuous vibration motion with various frequencies and displacements occurs, abnormal squeak noise may occur between the surface of the weather strip and the counter contact part. Squeak noise is frictional noise caused by stick-slip generated on the contact surface of the weather strip sealing part by the relative movement of the body structure part and the moving assembly. In the case of weather strip parts, a coating agent is applied to the contact surface in order to avoid squeak noise caused by non-ideal behavior in such moving parts. The coating agent is imparted with slipperiness to improve low-friction performance on the contact surface, and effectively avoids distortion on the contact surface due to non-ideal behavior, thereby minimizing the occurrence of noise. In addition, the coating agent is used to improve abrasion resistance caused by rubbing on the surface of the sealing part, which may occur when a driver gets in & out of the vehicle. In the case of the uncoated exposed rubber base material, chafing occurs on the surface due to repeated abrasion, and exterior quality problems may occur. Through this study, we developed a coating agent that can optimize the trade-off relationship of weather strip friction noise and abrasion performance, and developed a friction noise test mode based on real road driving data to verify the effect of improved performance. In addition, the effect of noise generation on the actual contact surface was analyzed through the friction noise test mode for each type of friction mating surface. Coating agents optimized from all these study were applied in our mass product vehicle. In particular, due to the low-friction characteristics between the body assembly and the weather strip, it was possible to minimize the price increase when manufacturing vehicles with non-glossy (matt color) body structures and parts with multi-contact conditions.

Mr. Hodong Kim, Senior Research Engineer, Hyundai motors, Body Structure Materials development Team