Method of blow molding a plastic container having an integrated single thickness skirt of bi-axially oriented PET

The method of forming an annular support base on the bottom of a blow molded bottle useful for carbonated beverages concurrently with the molding of said bottle, in a bottle mold in which said bottle has a center axis, comprising the steps of:

• forming a bottle preform with a closed bottom portion and an integral annular single thickness skirt portion of bi-axially orientable plastic material formed on said bottom portion in depending relation thereto;
• blow molding said preform in said bottle mold by introducing air under pressure into the interior thereof and concurrently therewith engaging said skirt portion in said mold with mechanical gripping means and stretching the skirt radially outwardly of said axis by moving said gripping means to form said annular support base in the form of a depending single thickness bi-axially oriented skirt in surrounding relation to the bottle bottom.

The method of forming a bi-axially oriented blow-molded bottle of bi-axially oriented plastic material with a pressure bottom and in which a bi-axially oriented integral skirt is formed on the bottle bottom providing for the support of said bottle, comprising the steps of:

• forming a bottle preform of said material with a closed preform bottom which forms the bottle bottom and an open top for blow molding and forming the mouth of said bottle and an integral depending skirt at said preform bottom;
• and
• in a bottle mold, blow molding said preform by introducing air under pressure through said open top, and simultaneously with said blow molding, as the air under pressure causes the preform bottom to move into contact with said bottle mold, gripping said skirt with mechanical gripping means within said mold and moving said mechanical gripping means outwardly thereby stretching said skirt radially so that said skirt is bi-axially oriented thereby forming said bi-axially oriented bottle having said bi-axially integral skirt.