Process and a device for measuring static and dynamic friction of sheet-shaped materials

A process for measuring friction of paper surfaces against paper surfaces for determining a coefficient of friction between said surfaces, which comprises arranging paper friction testing samples with contacting plane friction test surfaces between two mutually parallel opposite plane load surfaces, exerting with the aid of said load surfaces, an evenly distributed contact force on the friction test surfaces of the paper samples in a direction essentially normal to the friction test surfaces, maintaining a first of said samples and the load surfaces stationary, exerting a friction measuring tensile force on a second of said paper samples, the friction testing surfaces of which are in contact with the friction testing surfaces of said first sample, said tensile force being exerted with movable paper sample clamping means arranged for being moved in a direction of a straight line and for clamping said second paper sample for movement along the straight line which is in a direction of the friction test surfaces when measuring the friction, and measuring the combination of said essentially normal force, exerted with the aid of the load surfaces on the paper friction test surfaces, and said tensile force, which is required for a sliding movement of the friction test surfaces of said clamped second paper friction test sample relative to the contacting paper surfaces of said first paper friction test sample for determining said coefficient of friction.