Plastic bottles

Abstract

Plastic bottles ( 1 ) which are characterized in that: they are composed of neck ( 2 ), shoulder ( 3 ), body ( 4 ) and bottom ( 5 ); the cross-sectional shape at the body ( 3 ) is a regular polygon, the number of angles of which is an even number of not less than 4 nor more than 32; each angle of the polygon is rounded off by an arc ( 8 ) whose radius is not longer than half the radius of a circle circumscribed about the cross-sectional shape at body ( 3 ); cross-sectional shapes have the same shape at any portion of body ( 3 ); circles circumscribed about the cross-sectional shapes are identical with one another; the circumscribed circles have a center on the vertical central axis of body ( 3 ); and the cross-sectional shape of body ( 3 ) rotates around said central axis in proportion to height along said central axis.

1 . Plastic bottles which are characterized in that: they are composed of a neck, a shoulder, a body and a bottom; a cross-sectional shape at the body is a regular polygon, the number of angles of which is an even number of not less than 4 nor more than 32; each angle of the polygon is rounded off by an arc whose radius is not longer than half the radius of a circle circumscribed about the cross-sectional shape at the body; the cross-sectional shapes have the same shape at any portion of the body; the circles circumscribed about the cross-sectional shapes are identical with one another; the circumscribed circles have a center on the vertical central axis of the body; and the cross-sectional shape of the body rotates around said central axis in proportion to a height along said central axis.  
   
   
       2 . Plastic bottles of  claim 1  wherein the cross-sectional shape at the body rotates, the relation between rotation angle and height being 1°/mm or less.  
   
   
       3 . Plastic bottles of  claim 1  wherein the cross-sectional shape at the body rotates to make a rotation angle of 360°/the number of angles in the polygon.  
   
   
       4 . Plastic bottles of  claim 1  wherein also the cross-sectional shape at the shoulder is a polygon whose angles are each rounded off by an arc, and wherein the cross-sectional shape is not rotated.  
   
   
       5 . Plastic bottles of  claim 1  which are made from plyethylene terephthalate, and have been molded by biaxial stretch blow-molding.