Plastic bottle

Abstract

A plastic bottle is provided with a constricted portion and a non-constricted portion contiguous above and below with the constricted portion. One of the constricted portion or the non-constricted portion has a substantially polygonal cross-sectional shape, and the other one of the constricted portion or the non-constricted portion has a circular cross-sectional shape.

1 . A plastic bottle, comprising:
 a barrel portion having a constricted portion and a non-constricted portion contiguous above and below with the constricted portion,   wherein one of the constricted portion or the non-constricted portion has a substantially polygonal cross-sectional shape, and the other one of the constricted portion or the non-constricted portion has a circular cross-sectional shape.   
   
   
       2 . The plastic bottle of  claim 1 , wherein the constricted portion has a substantially polygonal cross-sectional shape, and the non-constricted portion has a circular cross-sectional shape. 
   
   
       3 . The plastic bottle of  claim 2 , wherein the constricted portion has a concave circumferential rib at a vertical center position thereof. 
   
   
       4 . The plastic bottle of  claim 3 , wherein the cross-sectional shape of the circumferential rib is circular. 
   
   
       5 . The plastic bottle of  claim 3 , wherein the constricted portion includes an upper polygonal surface above the circumferential rib and a lower polygonal surface below the circumferential rib;
 wherein the upper polygonal surface and the lower polygonal surface are formed in mutual vertical symmetry centered on the circumferential rib; and   wherein the upper polygonal surface and the lower polygonal surface respectively have substantially polygonal cross-sectional shapes, and are inclined on an inner side of the barrel portion toward the circumferential rib.   
   
   
       6 . The plastic bottle of  claim 5 , wherein the upper polygonal surface and the lower polygonal surface both include first and second surfaces alternately repeating in the circumferential direction, wherein the first surfaces incline toward the inside of the barrel portion at an angle different from that of the second surfaces. 
   
   
       7 . The plastic bottle of  claim 5 , wherein the upper polygonal surface and the lower polygonal surface respectively connect to the upper edge and lower edge of the circumferential rib by gradually changing surfaces. 
   
   
       8 . The plastic bottle of  claim 5 , wherein the upper polygonal surface and the lower polygonal surface respectively have circumferential ribs. 
   
   
       9 . The plastic bottle of  claim 2 , wherein the constricted portion includes:
 a deepest portion that is most constricted;   an upper polygonal surface; and   a lower polygonal surface,   wherein the upper polygonal surface and the lower polygonal surface are formed in mutual vertical symmetry centered on the deepest portion, and   wherein the upper polygonal surface and the lower polygonal surface respectively have substantially polygonal cross-sectional shapes, and are inclined on an inner side of the barrel portion toward the deepest portion.