Bag made of thermoplastic foil

The invention relates to a bag made of thermoplastic plastics film according to the preamble of claim 1.

In one known from EP-A-92885 bag of this type, the vents are located on the stacked in shallow blind inner walls of the gusset in a direction parallel to the top and bottom welds strip containing the gusset welds and the width of the projections outside the folding corresponds, on the inner parts of the diagonal split by the gusset welds parts of the walls of the middle area. In this known bag, the vents are indeed covered in the filled state by this überdekkenden outer gusset parts of the floor, so that they form no immediate outside, the bag perforated openings. In the formed by the gussets, outwardly open pockets can still but easily penetrate moisture and water and pass through the vents into the interior of the bag.

From US-A-3237844 a bag of thermoplastic film is known, which is provided in the region of its later opening to be closed with side Eckabschweißungen forming by a transverse weld head welds that are oblique. Further openings for venting the filled bag available. The Eckabschweißungen forming welds are executed with venting ducts forming interruptions.

The FR-A-2,512,424 shows a bag made of thermoplastic plastic are provided at the ventilation ducts and vents.

The object of the invention is therefore to provide a bag of the type described, which vents are better protected against external influences, and especially against the ingress of water or moisture into the sack.

This object is achieved in a bag of the type described by the features specified in the characterizing part of claim 1. The bag according to the invention is, as it is provided with a labyrinth arranged ventilation ducts and vents, so that moisture and water can not or only under extremely unfavorable conditions, reach the interior of the bag.

The labyrinth effect is additionally improved if only the inside, stacked in flat-lying unfilled sack walls of the gussets are provided with perforations.

In a further embodiment of the invention that the gussets of the flat-lying bags are provided with at least one guided through all four layers of the gusset perforation. Such continuous perforations are easier to install than the inner walls of the gussets detecting holes.

Advantageous developments are described in the dependent claims.

An embodiment of the invention will be explained hereinafter with reference to the drawing. In this the only figure shows a part of gusseted bags existing bag chain.

The single figure shows a bag chain 1 'from lying flat gusseted bags, which are formed from a gusseted 2 cunning web. The tubular web gusseted 2 is provided for producing the individual gusseted bags at equal distances from each other with bottom seams 3, with perforation 4 and Eckabschweißungen.

The Eckabschweißungen forming welds 5 'end at a distance from the outer edges 11 of the flattened tube 1'. In order to form labyrinth seals 13, extending parallel to the Eckabschweißnähten 5 'and at a small distance to these from the outer edges 11 obliquely inwardly extending welds 14. These welds 14 may have different lengths, as can be seen from the single figure.