SYNTHETIC RESIN PRODUCT HAVING ANNULAR CUT SURFACE, AND METHOD AND APPARATUS FOR FORMING THE CUT SURFACE

摘要

PROBLEM TO BE SOLVED: To easily separate one of outside and inside walls from the other one of them engaged with a container. SOLUTION: A synthetic resin product 100 is equipped with an annular body 110 having annular inside and outside walls 106, 108. The inside and outside walls 106, 108 are mutually connected through a plurality of bridging parts 118 arranged so as to provide an interval in the peripheral direction of the annular body 110 and annular cut surface 120 is present between the inside and outside walls 106, 108 excepting thre bridging parts 118. The cut surface 120 is inclined so as to approach the axial line of the annular body 110 from above to below.