A continuous process for preparing a pressure sensitive adhesive using a planetary roller extruder is described. The continuous process includes introducing at least one non-thermoplastic elastomer into a planetary roller extruder and initially compounding the non-thermoplastic elastomer in the planetary roller extruder to form an initially masticated non-thermoplastic elastomer. Then, a solid raw material, a liquid material, or both are introduced into the initially masticated non-thermoplastic elastomer in the planetary roller extruder, and subsequent compounding of the initially masticated non-thermoplastic elastomer with these additional components occurs to form an adhesive composition.