Flexible container

Abstract

 A sack has a body 10 which opens to form a tube. To form a releasable end closure for the sack, a pair of folds 12 are formed at the corners. Each fold 12 is in the form of a right-angled triangle so that the bases 14 of the folds 12 extend across the body 10 at right angles. The folds 12 form between them a peak 18 which is then folded back over the folds 12 to an extent whereby it overreaches the bases 14. Areas 20 of the return fold are pasted and adhered to the areas of the folds 12 and body 10 which they overlie.

Description

[0001] This invention relates to a flexible container.

[0002] Paper sacks are widely used as containers for a variety of products in industry and agriculture, and it is important that they should be inexpensive, secure for transport and storage, and easily opened when the contents are to be released.

[0003] According to the present invention there is provided a flexible container comprising a tubular body one end of which is closed by a fold pattern produced by forming a pair of side folds one from each side of the tubular body to form a central peak at the end of the body and providing a return fold of said peak to an extent whereby the peak overreaches the bases of the side folds, the fold pattern being releasably secured in position.

[0004] The releasable securing is preferably by means of an adhesive, for example paste, and the fold pattern provides the opportunity for pasting only a small area while ensuring a stable fold. The adhesive is preferably applied to areas of the side folds which form the return fold.

[0005] Preferably each of the side folds has a base D extending across the tubular body, the body being of flattened width W, in a relationship where D tends to equal (W-50mm)/2. Preferably also D is not less than (W-100mm)/2.

[0006] Preferably also the extent A by which the return fold overreaches the bases of the side folds is at least 30mm.

[0007] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Fig. 1 is a front view of an end portion of a paper sack before providing an end closure for the sack and with the body of the sack flattened;

Figs. 2 and 3 show the end portion of the sack of Fig. 1 at successive stages during the closure of its end; and

Fig. 4 shows the sack of Fig. 1 in final form.

[0008] Referring to the drawings, the sack of the illustrated embodiment of the invention has a body 10 which opens to form a tube for receiving silage or other loose material and which is shown folded flat in Figs. 1 to 4. The body 10 is made of paper having a thin lining of waterproof plastics material, and in its flattened form as shown the body 10 has a width W of 555mm.

[0009] In order to form a releasable end closure for the sack, a pair of triangular folds 12 are formed at the corners of the body 10 the folds 12 each having a base 14 which has a length D equal to 250mm long. Each fold 12 is generally in the form of a right-angled isosceles triangle so that the bases 14 extend across the body 10 at right angles to the body's central axis.

[0010] The triangular folds 12 form between them a peak 18 which is then folded back over the folds 12 to an extent whereby it overreaches the bases 14 by a distance A of 40mm (Fig. 3), and the areas 20 of the return fold shown hatched are pasted and adhered to the areas of the folds 12 and body 10 which they overlie.

[0011] A cap strip 22 (Fig. 4) can be fitted over the fold pattern, leaving the peak of the return fold exposed, for the purpose of maintaining neatness of the fold pattern and for bearing printed instructions and information.

[0012] With the fold pattern complete the body 10 can be opened out and filled through the opposite, open, end which is then sealed by stitching or other means. When the sack is subsequently to be emptied the peak 18 of the return fold is pulled in the direction of arrow B, releasing the return fold by overcoming the effect of the paste. The triangular folds 12 can then be turned down and the contents of the sack removed.

[0013] The fold pattern provides a secure but easily-releasable closure for the end of the sack and allows a small amount of adhesive to be used. The security of the closure derives from the extent of overreaching of the return fold beyond the bases 14 of the triangular folds 14, allied with the length of these bases 14 proportional to the width of the flattened body 10.

[0014] Further, it will be seen that the extreme corners of the peak 18 of the return fold are pasted to the body 10 of the sack, and this provides direct adhesion between areas which were originally on opposite faces of the flattened body.

[0015] Modifications and improvements may be made without departing from the scope of the invention.

Claims

1. A flexible container comprising a tubular body one end of which is closed by a fold pattern produced by forming a pair of said folds one from each side of the tubular body to form a central peak at the end of the body and providing a return fold of said peak to an extent whereby the peak overreaches the bases of the side folds, the fold pattern being releasably secured in position.

2. A flexible container as claimed in Claim 1, wherein the releasable securing is by means of an adhesive.

3. A flexible container as claimed in Claim 2, wherein the adhesive is applied to areas of the side folds which form the return fold.

4. A flexible container as claimed in any one of Claims 1-3, wherein each of the side folds has a base of length D extending across the tubular body, the body being of flattened width W, in a relationship where D is in a range of (W-50mm)/2 to (W-100 mm)/2.

5. A flexible container as claimed in any one of Claims 1-­3, wherein each of the side folds has a base of length D extending across the tubular body, the body being of flattened width W, in a relationship where D is equal to (W-­50 mm)/2.

6. A flexible container as claimed in any one of the preceding Claims, wherein the extent by which the return fold overreaches the base of the side folds is at least 30mm.

7. A flexible container as claimed in any one of the preceding claims, wherein the tubular body is a paper sack.

8. A flexible container as claimed in any one of the preceding Claims, wherein a closure strip is provided for retaining the fold pattern in position.

9. A method of closing a flexible container having a tubular body comprising forming a pair of side folds one from each side of the tubular body, to form a central peak at the end of the body, forming a return fold of said peak to overreach the bases of the side folds and securing the return fold in position.

Drawing