Flexible container

Abstract

 The invention relates to a flexible container for transport and storage of bulk material. The container may be equipped with an inner bag of impervious material. The container is emptied by cutting a hole in its bottom (2) or side walls and this part of the container is made of laminated material in order to avoid contamination by fiber particles or other contaminants of the container's content during discharge. The container's bottom (2) is preferable made of plastic fibers or threads laminated sheet plastic.

Description

[0001] The present invention relates to flexible containers for the tansport and storage of bulk material. The container comprises lifting loops, preferably integral ones, filling opening, a central section and a bottom section. The container can also be fitted with an inner bag of impervious material.

[0002] There is to day known several constructions of flexible containers of the above stated type. Regarding containers having integral lifting loops, reference is made to the applicants Norwegian patents _No.136.744 and No.138.134. Flexible containers according to these patents are preferably made from a single piece of woven material, for instance flat woven or circular woven polypropylene.

[0003] The containers bottom is formet by joining the lower sections of piece of material. According to the latter patent, cuts are made in the lower sections of said piece of material such that several flaps are formed. By joining these flaps in a special manner, there is formed a double bottom, which is stronger than the bottom of a single layer according to the former patent. For most applications, these containers are fitted with an inner bag of impervious material, for instance of polyethylene sheet material.

[0004] 5These flexible containers have attained extensive usage inter alia because of their simple construction which results in great strength as the strength immanent to the material used is utilized at its maximum.

[0005] The containers are intended for beeing used only once and are emptied by making a cut through both the woven material and the inner bag. usually the containers are emptied after first having been hoisted up by their lifting loops.

[0006] This method for emptying the container is simple and practical. It does however in certain cases have one disadvantage. Some of the fibers which the containers is made of are splitted or chipped when there is made a hole in the container. The fiber particles thus made may then be mixed with the product leaving the container. For some products there are very strict rules regarding purity and contamination by fiber particles can not be accepted.

[0007] An other type of flexible containers having an inner bag of impervious material is discribed in British patent No.1.536.237. The container itself is also in this case made from a strong material. The lifting loops are sewn on to the container walls and in the square bottom there is a central opening. The inner bag has openings in both ends, and these are lashed during storage and transport.

[0008] When emptying such a container, it is first hoisted up by its lifting loops and then the lower part of the inner bag is drawn out of the hole in the bottom and opened. In this case there is not made any cuts in the bottom and therefore contamination of the product is avoided.

[0009] Even though this construction and discharge method avoids contamination of the product, this way of solving the problem is not very practical. The container including the inner bag, becomes relatively expensive and both filling and discharge of the container is labour consuming.

[0010] The main object of the present invention was to develop a flexible container which was suitable for transport and storage of free flowing material beeing especially sensitive to contamination.

[0011] One special object was to design such container which would be emptied easily without contaminating by fibres and the like the content of the container when cuts or slitts were made in it during its discharge.

[0012] A futher object was to retain the container's advantages regarding strenght during hoisting by integral lifting loops and still having a container construction allowing discharge without contaminating the containers content.

[0013] Food products belong to the products which should not be contaminated by fiber particles and the like. Several types of food are well suited for beeing transported and stored in flexible containers. Extensive use of such containers for this purpose has however been obstructed because of the problems occuring during discharge.

[0014] Sevaral methods have been proposed for solving the problem, for instance as shown in the perviously mentioned British patent. This way of attacking the problem has however not lead to practical solutions. An other type of solutions have been related to using glue to bind the fibres, but these solutions have not worked, according to expectations. Gluing is labour consuming, the bottom become sticky for some time and when the bottom has been cut, both fiber and glue particles contaminated the product. It has also been tried to use tapes across the bottom. The tapes have however quite often loosened before the container was ready for discharge. Even when the tapes have covered the bottom until it was cut, this method did not completely prevent contamination of the product.

[0015] The inventer continued to work on this idea of binding the fibres, in spite of the discoraging results. It was then surprisingly found that the fibres could indeed be bound such that when the fibres were cut apart no fiber particles were ripped out to contaminate the product. This was obtained by laminating that part of the container in which there would be made cuts during discharge. Sheet plastic, for intance polyethylene film, was used to produce the laminated part. The inventer considered production of a separate bottom part of laminated material to be most practical. Woven polyolefin fabric could for instance be laminated with polyolefin film. The remaining part of the container, the lifting loops and side walls, could then be made from woven material. The lifting strength in the longitudinal fibers of the woven material was thus utilized as in the case of containers with intregral lifting loops. The relatively free orientations in the warp of the longitudinal fibers can thus be retained and the strenght of every one of these fiber are used during lifting.

[0016] The container can be manufactured from one piece of material or several ones joined together such that lifting loops are formed which are direct extentions of the container walls and thereby integral parts of them.

[0017] The special features of the invention are stated in the claims.

[0018] The invention will now be further described with reference to the drawings.

[0019] 

Fig. 1 and 2 Show the piece of material for manufacturing the container shown in fig.3.

Fig. 3 Shows a flexible container having a bottom part according to the invention.

[0020] In Fig. 1 there is shown a piece of material 1, preferably of woven material. The opening 3 will in the completed container constitute the filling opening. The material piece 2 will in the completed container form the bottom part and this piece 2 can be of the same material as piece 1, but in addition thereto it is laminated with a plastic sheet.

[0021] The material piece 1 is firsty joined together at the joints or seems 6 as shown in Fig.3. The material piece 2 can then be joined to the upper section of the container by means of seems 4,7 whereby is formed a container having integral lifting loops 5 and a square bottom 2.

[0022] From a manufacturing point of view it would be most practical to make the material pieces 1 and 2 separately. As the starting material for both are woven material and accordingly only a smaller part of the material has to be run through a laminating process.

[0023] It is of course possible to manufacture the flexible container by other methods than that shown in Fig. 3. Every construction will be within the scope of the invention when that part of the container, which is cut for emptying the container, consists of laminated material that does not contaminate the product during its discharge. For almost every type of flexible containers, it would be most practical, that the laminated part constitutes the containers bottom and that this bottom is a square one. Containers having such bottoms will stand firmly and are suitable for stacking.

[0024] The base material for the bottom part does not necessarily have to be made from woven resinous material. Other types of base material can be used if they meet the requirements regarding strength etc. Thus it may instead of polypropylene fibres be used mono filaments, cotton, nylon and the like, which then is laminated with sheet plastic. It is also within the scope of the invention to use other materials which per se meets the requirements. A flexible container could for instance be equipped with a bottom made from canvas. Such a solution would however comprise several practical disadvantages.

[0025] A container according to the invention may be equipped with an inner bag of impervious material which does not give off contaminating particles when cuts are made in it. The most practical material for such a bag would be polyethylene. The present invention thus resulted in a type of flexible containers which can be used for transport of for instance food stuffs and these containers can easily be discharged by cutting their bottom. The discharge does not imply any contamination of the product leaving the container. The most important obstruction for using such containers for .sensitive goods are accordingly removed by means of the invention.

Claims

1. Flexible container for transport and storage of bulk material, comprising a bottom section, side walls and lifting loops, and possibly also an inner bag of impervious material, characterized in that that part of the container which is cut during discharge consists of laminated material not giving off fiber particles or any other contaminants during discharge of the container.

2. Flexible container according to claim 1 characterized in that the container's bottom consists of plastic fibers or treads laminated with sheet plastic and that the container has a square bottom.

Drawing