Method of manufacturing headerless produce bags with increased adhesion

A method useful for manufacturing a headerless plastic bag from sheets of thin plastic film, comprising:

• providing a first continuous web sheet aligned in facing relation to a second continuos web sheet at a forming station comprising a first platen to form aligned first and second sheets;
• applying and then removing pressure and heat at a section of the aligned first and second sheets using the platen to form heat sealed sides and a mouth of a headerless plastic bag;
• advancing the headerless plastic bag formed in the section of the aligned first and second sheets from the forming station to a plasma treatment station configured to directly apply low temperature corona discharge plasma treatment to only the first sheet;
• treating the first sheet at the plasma treatment station under zero added pressure with low temperature corona discharge plasma to increase the surface charge magnitude of the first sheet to a surface energy of at least 43 Dyne wherein the surface energy is sufficient to cause the headerless plastic bag to adhere to an adjacent second plastic bag with a force sufficient to automatically open the mouth of the headerless plastic bag upon removal of the second bag from therefrom;
• advancing the treated headerless plastic bag formed in the section of the aligned first and second sheets to a cutting station;
• cutting the first and second aligned sheets to separate the headerless plastic bag from the first sheet and the second sheet;
• advancing the cut headerless plastic bag to a stacking station comprising a second platen;
• stacking the cut headerless plastic bag at the stacking station onto a second plastic bag;
• and
• forming concurrently both a first pair of mated recesses in the first sheet and the second sheet of a first plastic bag, the first pair of recesses configured to cause the first sheet to releasably mechanically adhere to the second sheet, and a second pair of mated recesses in the second plastic bag, using the second platen, a recess of the first pair of mated recesses mated with a recess of the second pair of mated recesses, wherein the adherence between the second plastic bag and the cut headerless plastic bag caused by the plasma treatment, combined with the adherence between the first sheet and the second sheet of the cut headerless plastic bag caused by the mated first pair of recesses, and the adherence between the cut headerless plastic bag and the second plastic bag caused by the first pair of recesses in the first plastic bag mated with the second pair of recesses in the second plastic bag, together cause the cut headerless plastic bag to automatically open upon separation of the second plastic bag from the cut headerless plastic bag.