A heat insulating paper cup having an improved seal. The cup (1) can include a body member (3) having an inside surface and an outside surface, and a bottom panel member (6) having an upper surface (7) and a bottom surface (8). The body member comprises a paper sheet (2) which is coated (or in some instances partially coated) on its outside surface with a heat insulating layer of foamed low density polyethylene (4) and on its inside surface with an unfoamed modified low density polyethylene (5). The bottom panel member (6) is coated on its upper surface with a foamed or an unfoamed low density polyethylene or foamed or unfoamed modified low density polyethylene (7). The body member (3) and bottom panel member are oriented and joined to form a heat seal at an interface between a portion of the unfoamed modified low density polyethylene coated on the inside surface (5) of the body member and a portion of unfoamed low density polyethylene or unfoamed modified low density polyethylene or unfoamed modified low density polyethylene coated on the upper surface (7) of the bottom panel (6).