Method and apparatus for bag closure and sealing

A method of pinch closing and sealing a bag made of polymeric material, comprising:

• the bag having a heat activated first adhesive layer applied on a first section of a first panel of the bag;
• the bag having a heat activated second adhesive layer applied on a stepped construction of the bag, the stepped construction of the bag comprising a second section of the first panel, portions of side gussets of the bag and a portion of the second panel including a flap portion, wherein the first adhesive layer and the second adhesive layer have respective heat activation temperatures below the softening point temperature of the polymeric material;
• pinch closing an open end of the bag by closing the first panel and the second panel against each other adjacent the open end;
• creasing the bag along a fold line, wherein the fold line is spaced from the end of the bag;
• applying heat by passing the bag through a pinch sealing unit that blows hot air onto the first adhesive layer and the second adhesive layer at a temperature below the softening point temperature of the polymeric material, by using a hot air manifold of the pinch sealing unit, the hot air manifold having a hot air chamber supplied with hot air under pressure, and a top wall on the hot air chamber provided with a distribution of first air passages for blowing hot air under pressure to heat the second adhesive layer to its adhesive state, and a back wall on the hot air chamber provided with a distribution of second air passages blowing hot air under pressure to heat the first adhesive layer to its adhesive state:
• and
• folding the bag along the fold line to form an adhesive-to adhesive seal by contact between the first adhesive layer and the second adhesive layer.

A method of pinch closing and sealing a bag made of polymeric material, comprising:

• the bag having a heat activated first adhesive layer applied on a first panel of the bag;
• the bag having a heat activated second adhesive layer applied on a second panel of the bag including a flap portion, wherein the first adhesive layer and the second adhesive layer have respective heat activation temperatures below the softening point temperature of the polymeric material;
• pinch closing an end of the bag by closing the first panel and the second panel against each other adjacent the end of the bag, followed by creasing the bag along a fold line, wherein the fold line is spaced from the end of the bag;
• applying heat to the first adhesive layer and the second adhesive layer at a temperature below the softening point temperature of the polymeric material to activate the first adhesive layer to its adhesive state, and to activate the second adhesive layer to its adhesive state;
• and
• folding the bag along the fold line to form an adhesive-to adhesive seal by contact between the first adhesive layer and the second adhesive layer.