Bottom folded bags

© Beginning of patent period: 1975 08 15

Longest possible duration:

© Issued on: 1976 06 10 © inventor:

© dependence:

© Pamphlets considered to delineate the prior art:

OE 330 066 - 2 -

Nr.330066

The invention relates to a bottom fold bag made of a composite film, which is composed of at least two mutually different layers, of which the inner layer consists of a weldable thermoplastic material, with two bag walls and a bottom fold, which together have a W-shaped cross-section with in the bottom fold area have four foil layers and which are connected together along their side edges by welds.

For example, in a bag of this type known for example from German Auslegeschrift 1281140, the two plies of the bottom pleat in the area of ​​the side seams of the bag have holes through which the bag walls are in contact and welded so that the side edges of the bottom pleat are closed. This connection of the bottom fold ends is simple and strong in construction, when the folding of the film strip into a W-shaped cross section after the attachment of the holes is accurately performed. However, since the holes in the area of ​​the bottom fold must be punched out to a W before folding, the film strip tends to warp upon folding to the weakened through the holes zones, which can lead to uncontrolled wrinkling. Thus it happens that the matching holes of a pair do not exactly coincide. The result is then a reduced area for welding together the bag walls in the bottom fold area.

The invention has for its object to provide a stably ground fold bag in which the lateral ends of the bottom fold are firmly closed and can be easily produced.

This object is achieved according to the invention in that the bag walls in the bottom fold and the two layers of the bottom fold near the side edges have opaque perforations, in which from the surrounding areas of the four film layers of the thermoplastic inner layer in each case a part of the plastic below the action of pressure and heat is displaced and these parts in the perforations are fused together in a weld.

A particularly high strength of the connection of the bottom fold ends results in a further embodiment of the invention in that a plurality of perforations are provided one above the other in the side seams in each side edge region of the bottom fold and the bag walls in the side seams.

To produce bottom folded bags from a strip of composite film by W-folding, attaching side seams across the strip direction and separating individual bags from the bag chain, it has been found to be particularly advantageous according to the invention that after the W-shaped folding of the strip in this Punchings are made in the area of ​​the side seams and then exposed to the surrounding areas of the perforations pressure and heat.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. 2 shows a second embodiment of a bottom fold bag in front view, FIG. 3 greatly enlarges a part of the bottom fold bag according to FIG. 1 in the area of ​​the bottom fold in cross section, and FIG. 4 shows an apparatus for producing it a bottom fold bag according to Fig.l simplified in perspective view.

The bottom fold bag has a front and rear bag wall -11, 12- and between them at the bottom of a bottom fold -13-, which has reversed V two layers. The bag is formed by W-folding a band of composite sheet composed of at least two mutually different layers 16, 17, one of which is a weldable thermoplastic, for example polyethylene. This layer, which lies inside the bag, forms a protective layer for the filling material and serves to weld the layers of the film. The outer layer -17- consists for example of cellophane or polyester film, which has a Dichtigkeits- and carrier function.

Above the bottom fold -13 - are the two adjacent bag walls -11,12- im

Area of ​​their margins by vertical side seams -20, 21- welded together. In the area of ​​the bottom fold -13- they are also in the region of their side edges and bottom edges with the adjacent layers of the bottom fold -13- by the side seams -20, 21- and by horizontal bottom edge seams --22-, welded.

In order to ensure the stability of the filled bottom fold bag, the two lateral ends of the bottom fold -13- are closed. For this purpose, in the area of ​​the bottom fold -13- in the two side edge zones, in which the elongated surfaces of the side seams -20,21- lie, the two bag walls -11, 12- and the two layers of the bottom fold -13- with four superimposed punched out -24- provided. In these punched -24- is thermoplastic from the

Inner layers -16 - pressed the various film layers and connected in a solidified melt. The annular melting furnaces form welds -25-, which hold the bottom fold -13- at the ends firmly (Figure 3).

The described bottom fold bag is made as follows:

From a supply roll -30- a composite film -31- is peeled off and a strip

--32- folded with W-shaped cross-section. At intervals of the width of the bag to be produced in the area of ​​the retracted bottom fold -13- with a punch -33- in the four - 3 -

No.330066 adjacent layers of the strip -32- punched -24- mounted, which are arranged in two vertical rows of four. Thereafter, at a subsequent station with L-shaped welding jaws, the transverse side seams -20, 21- and the longitudinal bottom edge seams -22- are attached to the strip -32- so that the two rows of punches -24- are in their surface , In the production of the side seams -20, 21-, which are produced simultaneously for a preceding and a subsequent bag immediately adjacent to each other, connect in the seam area under the action of pressure and heat, the inner layers -16- of the bag walls -11,12- in the upper part of the bag and the inner layers -16- of the bag walls -11,12- with the adjacent inner layers -16- of the layers of the bottom fold -13- in the lower part of the bag. In this case, each part of the thermoplastic layer -16- of the die-24- surrounding layers of the composite film in the punched -24- displaced as melts, which unite in the punched -24- to form an annular weld -25-. If necessary, the punching and sealing points can be cold pressed after the seal. From the bag chain -35- thus produced, the individual bags are separated with scissors -36-.

The punched -24- have preferably circular shape. The diameter of the circle is smaller than the width of the side seams -20,21-. As shown in the embodiment of Figure 2, the punched holes can also have the shape of a slot or oval. Furthermore, other geometric shapes for the punching possible, such as triangles, squares or the like.

To have enough welding material available for producing the weld seams in the punched-outs, the side seams -20, 21- in the area of ​​the bottom fold -13- are wider in the embodiment according to FIG. 2 than in the area above them, in which the two Bag walls -11, 12- are welded directly together. To displace thermoplastic material into the punched -24- it is advantageous to the parts of the side seams -20, 21-, which lie in the region of the bottom fold -13-, again pressure and heat to obtain a sufficiently strong weld.

In the described embodiment of a bag, a two-layered packaging material was used. In the context of the invention it is also possible to use packaging materials with more than two layers, of which the inner layer is weldable, whereas the outer layer has no or a higher melting point.