Patent ID: 7651004

Claim:
A linerless closure of one-piece integrally molded plastic construction, which includes: a base wall and a cylindrical skirt for attaching the closure to a container neck finish, said base wall having a central portion with a first thickness, a first peripheral portion contiguous with said central portion and having a second thickness greater than said first thickness, and a second peripheral portion connecting said first peripheral portion and said skirt and having a third thickness greater than said second thickness, a first circumferentially continuous annular wall extending away from said base wall at a juncture of said central and first peripheral portions of said base wall, a second circumferentially continuous annular wall extending away from said base wall at a juncture of said first and second peripheral portions of said base wall, said first and second annular walls being spaced from each other to receive therebetween an end portion of the container neck finish when the closure is attached to the container neck finish, at least one of said annular walls having a circumferentially continuous annular projection extending toward the opposing annular wall, said annular projection being axially flexible with respect to said at least one annular wall for bending and folding toward said base wall and toward said at least one annular wall upon engagement with the container neck finish end portion, said at least one annular projection including an undersurface facing away from said base wall to contribute to the flexibility of said at least one annular projection to ensure that said at least one annular projection will fold into sealing engagement with an outside cylindrical surface of the container neck finish, wherein said first peripheral portion of said closure base wall has an undersurface between said first and second annular walls, and wherein said closure is sealingly engageable with the container neck finish by engagement of said closure base wall undersurface with an end surface of the container neck finish and by engagement of said at least one annular projection undersurface with an outside cylindrical surface of the container neck finish.