This question also has an answer here (in German):
Wann darf man Markennamen bevorzugen?
There are some famous brands, whose names overtook the name of the original product and when the name of the brand is said, everybody understands what is meant.
In Germany, I only know two examples;
Tempo is used, when Taschentuch is meant
Tupperware is used, when Essensbehälter is meant
What are other examples?