GB2155432A

GB2155432A - Re-usable sack

Info

Publication number: GB2155432A
Application number: GB8505916A
Authority: GB
Inventors: Jens Christian Anderssen; Erik Koll Larssen; Bjorn Richard Petterson
Original assignee: Norsk Hydro ASA
Current assignee: Norsk Hydro ASA
Priority date: 1984-03-08
Filing date: 1985-03-07
Publication date: 1985-09-25
Also published as: NO153922B; NO840877L; GB2155432B; NO153922C; GB8505916D0; IN163232B

Abstract

A re-usable sack consists of an outer sack (1) and at least one impermeable inner sack (9) with an extra length (10) in relation to the outer sack. The inner sack is fastened to the outer sack by sewing, gluing or welding (5) so that the sack has an open end (3) before filling of the goods. The extra length (10) is placed opposite to the open end of the sack and is turned back, folded or rolled together inside the outer sack. After filling with goods the reuseable sack is closed and made impermeable. The sack is opened at the opposite end (4) to the inlet opening, whereby the extra length (10) of the inner sack is released. <IMAGE>

Description

SPECIFICATION Multilayered sack and process of producing same The present invention relates to a multilayered, impermeable sack and to a process of producing such a sack.

Sacks for packing of goods are usually made of fabrics, paper, woven strips of plastic film, coated fabrics, coated paper, laminated woven plastic and plastic film.

Sacks for packing of goods usually consist of only one layer (garbage sacks) and two- or multilayered sacks in permeable or impermeable materials.

The present invention concerns sacks of at least two layers of material, where the outer sack may be impermeable or permeable, while the inner sack has to be impermeable.

The following of the materials used for sacks mentioned above are permeable: fabrics, paper and woven strips of plastic film while the following are impermeable: coated fabrics and paper, laminated woven plastic and plastic film.

Such two-layered sacks are especially used for transport and storing of e.g. ammonium nitrate to be used in explosives, but are on the other hand less suited for repeated use of the same goods.

The reason is that the double sack is filled completely in the factory and it is closed in such a way that it is watertight. When it is opened, it will usually not be possible to put more goods into the sack and it is at least not possible to close it in a water-tight and otherwise a proper way.

One can of course, which is also done, fill only 2/ 3 of the sack and use the remaining part of the sack for closing. Such a process involves that for every second filled sack another empty sack is needed in order to have enough room for the goods so that the sacks can be closed properly.

Usually such sacks are not available at a building site and are really an unnecessary cost for the contractor or owner.

The purpose of the present invention is to solve the above mentioned problem, and accordingly to be able to use a two-layered sack of the above mentioned type several times without using extra sacks or reducing the amount of goods in the sack and that this type of sack can be properly closed also when the sack is reused.

In accordance with the invention the problem is solved by making the inner sack longer than the outer sack, the extra length being preferably turned back over the inner sack within the outer sack.

By filling the sack at the opposite end of the extra length, and by turning the sack after it has been filled and closed so that it is opened from the side with the extra length, the extra length will be free when the sack is opened. The extra length can then be used for tying.

The present invention includes the sack itself and a process of producing the sack according to the claims.

The invention will now be further described by way of example with reference to the accompanying drawings in which: Figure 1 is a plan view of a sack in accordance with this invention, Figure 2 is a section on the line A-A of Figure 1, and Figure 3 is an elevation of the sack of Figure 1 in an alternative arrangement.

Figure 1 shows the outer sack (1) after filling of the goods and after the sack has been closed. The outer sack, which is made from woven material for better securing of the seam, is sewn in the side (2), in the top (3) and in the bottom (4), the stitches being single chain work in the side (2) and in the bottom (4). At the top (3) two parallel seams (5 and 6) are used, and for additional tightening and reinforcement a welded seam (7) extends across the sack parallel to the seams (5 and 6). The welding seam (7) ensures that the inner sack (9) - see Figure 2- is closed and made impermeable. The seam (5) does not necessarily have to reach quite out to the folds of the sack, as it is sufficient to fasten the inner sack to the outer sack with shorter seams.

To ensure that the sack is opened from the correct end when used, the text on the outside of the sack (1) is turned upside down. When the sack (1) is filled, the text (8) is thus shown upside down, while by opening the sack it is seen to that the sack is turned so that the text (8) is shown the right way. In other words, when opening the sack the user will open it at the "bottom" (4), while that part which was the top (3) during the filling has now become the bottom.

The reason for this arrangement is shown by the section A-A through the sack, see Figures 1 and 2.

In Figure 2 the outer sack (1) is sewn in the top (3) and in the bottom (4) with single chain work. Inside the outer sack (1) the inner sack (9) is seen with its extra length (10) folded up in closed condition. The extra length is defined as that part of the inner sack which is necessary to be able to draw the opening of the sack together and tie it properly and make it watertight. In the top (3) the inner sack (9) is fastened to the outer sack (1) with a single seam (5). In this way the inner sack will be fastened to the outer sack and the goods can be filled into the sack without danger of drawing the inner sack into the outer sack together with the goods.

Another advantage of fastening of the inner sack to the outer sack is that by filling the goods into the inner sack, spilling of goods between the two sacks is compietedly avoided.

After filling of the goods, the sides of the sack are sewn together in the top with another seam (6), as shown in Figure 1, where the welded seam (7) is shown as a narrow, stripped field.

If necessary the extra length (10) of the inner sack (9) can be welded at the end, but it can also be open. Then the goods will press the inner sack towards the outer sack and thus prevent the goods from leaking out of the inner sack.

Figure 3 shows an arrangement where the inner sack (9) is folded at the open end forming the folded part (11). The folded part is shown tied up (12). The outer sack (1) is folded back to show the folded part (11). The former top (3) is now seen in the bottom of the sack, and the bottom (4) is now seen folded back. The text (8) is shown the right way. The outer sack (1) is stiff enough to remain in upright position without being fastened to, the in ner sack (9) or by being folded down as shown in the figure.

The inlet (3) opening is preferably shaped as shown in Figure 2, but it can also have a charging valve (not shown on the figures). In the latter case it is required that the charging valve is mounted within the sack and that the inlet opening (3) is closed. The invention is not concerned with the shape of the inlet opening (3) as this can have many different shapes. However, if the sack is fitted with a charging valve, the inner sack (9) shouid be impermeable when it is closed after the filling.

The sack which conists of an outer sack (1) of woven material, e.g. polypropylene and an inner sack (9) of impermeable plastic film, e.g. polyethyl ene, is made in the following way: The woven material in the right width is folded once in the longitudinal direction and is sewn to gether by a hem, so that the side (2) of the sack is formed. Then the resulting casing is cut into suita ble lengths and provided with a hem where the bottom (4) of the sack is going to be. The inner sack (9) is of plastic film and is made by welding a casing of plastic film in one end and by cutting the film in suitable lengths according to the lengths of the outer sack and with some extra length. The in ner sack is then pulled over a guiding arrange ment, and the extra length is turned in over the inner sack. Then the inner sack is pushed into the outer sack.When the inner sack is located inside the outer sack, the guiding arrangement is pulled out of the sack. Then the inner sack is sewn, glued or welded to the outer sack with a single seam, a straight glued joint or welded seam. The outer sack can then either be folded over the inner sack, as shown in Figure 2 where the fold is marked with (14), or the inner sack can be fastened to the outer sack without a fold.

It is not crucial to the invention that the seams in the outer sack are provided with a hem or ordinary straight seam. Nor is it crucial to the invention that chain work stitches are used instead of an ordinary seam in sewing the different parts of the sacks.

It is, however, an advantage for the use of the sack that the seam in the "bottom" (4) is of single chain work stitches as these seams are easy to unravel.

After filling of the goods in the sack it is sewn together in the top (2) with a single seam (6) parallel to the seam (5). Then the inner sack is welded beneath the seam (6) so that a watertight connection in the shape of a welded seam (7) is formed.

If desired and when the material in the inner sack is suitable for gluing, the welded seam can be replaced with a straight glued joint (7).

It is therefore not crucial to the invention whether the sack is welded or glued provided that the joint is strong enough.

When used, the sack (9) is turned so that the text (8) will be in the correct way in proportion to the user.

With the present invention a neat solution is provided which is especially useful to the not unim portant problem of production of safety explosives at the working site.

Claims

1. A multilayered sack comprising at least an outer sack and an inner sack, at least the inner sack (9) being made of impermeable material, characterised in that both the outer sack and the inner sack are fastened together at least in one place, in that the inner sack has an extra length or neck as compared with the outer sack, and in that the extra length has an extension that makes possible a proper closing of the inner sack when it is reused.

2. A multilayered sack according to claim 1, wherein the extra length of the inner sack is turned back, folded or rolled together within the outer sack.

3. A multilayered sack according to Claim 1 or 2 wherein the extra length of the inner sack is either closed or open.

4. A multilayered sack according to any of the preceding claims wherein the extra length of the sack (10) is placed opposite to the open end (3) of the sack.

5. A process of producing a multilayered sack according to clairr(s 1 to 4, characterised in that the inner sack with its extra length is put into the outer sack by a continuous or a discontinuous process, after which the inner sack at least in one place which preferably is at the filling site, inlet opening, is fastened to the outer sack so that the combined sack consisting of at least one outer sack and at least one inner sack remains open after they have been fastened together, after which the inner sack is filled and then closed and made impermeable.

6. A process of producing a multilayered sack according to claim 5, wherein the filled inner sack is closed and made impermeable by a welded seam or by both a sewn seam and a welded seam.

7. A process of producing a multilayered sack according to claim 5 or 6 wherein the extra length of the inner sack is turned back, folded or rolled together, within the outer sack in the opposite end from the open end of the sack.

8. A multilayered sack substantially as hereinbefore described with reference to the accompanying drawings.