| 摘要 |
PROBLEM TO BE SOLVED: To provide a valve stem seal having superior dynamic frictional property.SOLUTION: In a valve stem seal including an elastic member having a seal lip portion disposed on a terminal end of a valve stem guide and slidably kept into contact with a valve stem of an engine, the elastic member is composed of a composition including fluorine rubber (A) and a silicon dioxide-containing compound (B), and the seal lip portion has a ratio(X/Y) of X and Y mentioned below, of 1.2 or more. X is a ratio [intensity (bX)/intensity (aX)] in which (bX) is intensity at an absorption position 1097 cm, and (aX) is intensity at an absorption position 1395 cm, obtained by measuring a surface of the seal lip portion by infrared spectroscopy analysis, and Y is a ratio of [intensity (bY)/intensity (aY)] in which (bY) is intensity at an absorption position 1097 cm, and (aY) is intensity at an absorption position 1395 cm, obtained by measuring the inside of the seal lip portion by infrared spectroscopy analysis.SELECTED DRAWING: None |
