Container lid comprising metal body and synthetic resin liner

Abstract

A container lid comprising a body made of a thin metal plate, the body having a top panel wall, and a skirt wall extending downwardly from the peripheral edge of the top panel wall; and a synthetic resin liner disposed on the inner surface of the top panel wall of the body, the liner being composed of a first layer ( 26 ) formed on the inner surface of the top panel wall; and a second layer ( 28 ) formed on the lower surface of the first layer. The thickness of a radially inner region of an outer peripheral edge portion ( 32 ) of the first layer is rendered larger than the thickness of a radially outer region of a central portion ( 30 ) of the first layer to make a step present at the boundary between the central portion and the outer peripheral edge portion. A toroidal thickness varying region ( 34 ) whose thickness gradually decreases radially outwardly is made present in the central portion of the first layer.

1 . A container lid comprising a body made of a thin metal plate, the body having a circular top panel wall, and a cylindrical skirt wall extending downwardly from a peripheral edge of the top panel wall; and a synthetic resin liner disposed on an inner surface of the top panel wall of the body,
 the liner being composed of a first layer formed by press-molding a rigid synthetic resin material supplied to the inner surface of the top panel wall; and a second layer formed by press-molding a flexible synthetic resin material supplied to a lower surface of the first layer,   the first layer of the liner having a circular central portion extending along the inner surface of the top panel wall of the body; and a toroidal outer peripheral edge portion extending along an inner surface of an outer peripheral edge part of the top panel wall of the body and along an inner surface of an upper end part of the skirt wall, and   the second layer of the liner being laminated to the central portion of the first layer,   wherein a wall thickness of a radially inner region of the outer peripheral edge portion of the first layer of the liner is larger than a wall thickness of a radially outer region of the central portion of the first layer, and a step is present at a boundary between the central portion and the outer peripheral edge portion.   
     
     
         2 . The container lid according to  claim 1 , wherein the step measures 0.05 to 0.40 mm. 
     
     
         3 . The container lid according to  claim 1 , wherein a toroidal thickness varying region whose thickness gradually decreases radially outwardly is present in the central portion of the first layer. 
     
     
         4 . The container lid according to  claim 3 , wherein
 the second layer has a circular thin-walled central portion, and a toroidal thick-walled outer peripheral edge portion;   an annular protrusion protruding downward is present in a radially inner region of the thick-walled outer peripheral edge portion; and   an outer peripheral edge of the thickness varying region of the first layer is located radially inwardly of an inner peripheral edge of the annular protrusion.   
     
     
         5 . The container lid according to  claim 4 , wherein
 the thickness varying region of the first layer is located opposite a radially outer region of the thin-walled central portion of the second layer; and   a thickness of the radially outer region of the thin-walled central portion of the second layer gradually increases radially outwardly in accordance with thickness variations of the thickness varying region of the first layer.   
     
     
         6 . The container lid according to  claim 3 , wherein the thickness varying region inclines at an inclination angle of 0.5 to 3.0 degrees relative to a horizontal. 
     
     
         7 . The container lid according to  claim 4 ,
 which is applied to a container made of a thin metal plate, the container having an outward curl formed at a leading end of a mouth-neck section thereof,   wherein an outer peripheral surface of the annular protrusion of the second layer of the liner is brought into intimate contact with an upper end part of an inner peripheral surface of the outward curl; and   a lower surface of a radially outer region of the thick-walled outer peripheral edge portion located radially outwardly of the annular projection is brought into intimate contact with an upper surface to an outer peripheral surface of the outward curl.   
     
     
         8 . A container lid comprising a body made of a thin metal plate, the body having a circular top panel wall, and a cylindrical skirt wall extending downwardly from a peripheral edge of the top panel wall; and a synthetic resin liner disposed on an inner surface of the top panel wall of the body,
 the liner being composed of a first layer formed by press-molding a rigid synthetic resin material supplied to the inner surface of the top panel wall; and a second layer formed by press-molding a flexible synthetic resin material supplied to a lower surface of the first layer,   the first layer of the liner having a circular central portion extending along the inner surface of the top panel wall of the body; and a toroidal outer peripheral edge portion extending along an inner surface of an outer peripheral edge part of the top panel wall of the body and along an inner surface of an upper end part of the skirt wall, and   the second layer of the liner being laminated to the central portion of the first layer,   wherein a toroidal thickness varying region whose thickness gradually decreases radially outwardly is present in the central portion of the first layer.   
     
     
         9 . The container lid according to  claim 8 , wherein
 the second layer has a circular thin-walled central portion, and a toroidal thick-walled outer peripheral edge portion;   an annular protrusion protruding downward is present in a radially inner region of the thick-walled outer peripheral edge portion; and   an outer peripheral edge of the thickness varying region of the first layer is located radially inwardly of an inner peripheral edge of the annular protrusion.   
     
     
         10 . The container lid according to  claim 9 , wherein
 the thickness varying region of the first layer is located opposite a radially outer region of the thin-walled central portion of the second layer; and   a thickness of the radially outer region of the thin-walled central portion of the second layer gradually increases radially outwardly in accordance with thickness variations of the thickness varying region of the first layer.   
     
     
         11 . The container lid according to  claim 8 , wherein the thickness varying region inclines at an inclination angle of 0.5 to 3.0 degrees relative to a horizontal. 
     
     
         12 . The container lid according to  claim 8 ,
 which is applied to a container made of a thin metal plate, the container having an outward curl formed at a leading end of a mouth-neck section thereof,   wherein an outer peripheral surface of the annular protrusion of the second layer of the liner is brought into intimate contact with an upper end part of an inner peripheral surface of the outward curl; and   a lower surface of a radially outer region of the thick-walled outer peripheral edge portion located radially outwardly of the annular projection is brought into intimate contact with an upper surface to an outer peripheral surface of the outward curl.