EP0003256B1

EP0003256B1 - Flexible tubular container and method of making it

Info

Publication number: EP0003256B1
Application number: EP78300769A
Authority: EP
Inventors: Arthur Stephen Wright
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1978-01-30
Filing date: 1978-12-07
Publication date: 1981-09-09
Also published as: HK8583A; NZ189208A; BR7900523A; CA1117492A; EP0003256A1; IE47763B1; IT7919414A0; ZA786996B; IT1110914B; IE782451L; MY8300188A; DE2861064D1; AU4268978A

Description

This invention relates to a flexible tubular container which is sealed at one end by a compression closure embracing the gathered tube end and to a method of making the said container. Such containers are generally made by dividing a continuous length of stock tubular material, usually plastics material and often in the form known as 'lay-flat' seamless tube. The closures are often applied to a filled continuous length of tube before the tube is cut transversely to separate the individual sealed containers.
In known flexible tubular containers, for example, those containing liquid or gelatinous materials such as slurry explosive compositions or grouting resin for anchor bolts used in mines, the tube ends are usually closed by self-sustaining metal or plastic clips. These clips are rather expensive and difficult to apply. The metal clips constitute a hazard in blasting operations in mines as they may give rise to sparks which could ignite firedamp. Also during application to the tube and in blasting the clips can be projected at high velocity and thus be a danger to personnel. The plastic clips tend to expand when the containers are stored under pressure with consequent leakage or exposure of the contents.
It is known from United States Patent Specification No. 3,785,406 (Delmar) to form containers from continuous flexible tube by binding a constricted portion of tube with two separate wires held in position by tying the wire ends and cutting the tube transversely between the wire closures. Also in United States Patent Specification No. 3,620,774 (Ford et al) it is proposed to close one end of a flexible tubular container with a ligature helically wound around a gathered neck of the container and maintained in position by adhesive material. Neither of these forms of end-closure have been proposed for closing containers for explosive material.
It is an object of this invention to provide an improved flexible tubular container, which is reliab!e and suitable for explosive for use in coal mines. and a method of making such a container.
In accordance with this invention a flexible tubular container having at least one of its ends closed by a length of filamentary material tightly wound in a generally helical manner along a gathered and constricted portion of said end and held in position by adhesive material, is characterised in that the container end and the filamentary material are coterminous and substantially the whole of the end turn of filamentary material lies in the same plane as the container end.
Preferably the filamentary material is bonded both to itself and to the tubular container by a mutually compatible adhesive material.
Convenient filamentary materials include flexible tying materials such as cord, tape, string and textile yarn. The adhesive material is advantageously a fast acting adhesive such as cyanoacrylate adhesive or a hot-melt adhesive comprising a mixture of thermoplastics resin and tackifying resin such as a mixture of ethylene/vinyl acetate copolymer and rosin ester.
The container is advantageously made from a continuous length of flexible tube by a method which comprises gathering and constricting a portion of the flexible tube, binding the constricted portion with a length of filamentary material tightly wound in a generally helical manner along the constricted portion of the tube and applying adhesive material to the filamentary material to fix said filamentary material in position on the constricted tube portion, and is characterised in that the constricted portion of the tube and length of filamentary material are cut transversely to define two closed container ends on adjacent portions of the flexible tube with each closed end and substantially the whole of the turn of filamentary material adjacent thereto lying in the same piane. In a preferred method oi making a container sealed with similar closures at both ends a continuous length of flexible tube is gathered and constricted at each of two spaced apart positions, a length of filamentary material is tightly wound in a generally helical manner along each constricted tube portion and fixed thereon with adhesive material and the filamentary material and constricted tube portions are cut transversely at each position to separate a tubular container closed at both ends from the adjacent closed portions of the flexible tube. It will be understood that the tube may be constricted, bound and cut at the two positions consecutively, simultaneously or, in any order which is convenient. Thus the tube may be cut at one end of the container either before or after the filamentary material is applied around the tube at the position defining the other end of the tube.
Tubes of smaller diameter, for example, 5 cm diameter or less, can advantageously be gathered and constricted by the application of the filamentary material but with large diameter tubes or tubes containing highly viscous filling material it may be desirable to pre-waist the tube at the positions where the filamentary material is to be wound.
The adhesive may be applied to the filamentary material as it is being wound around the tuoe or it may be applied in a preliminary operation, the filamentary material serving as a carrier for the adhesive.
Advantageously the tubular container may contain the filling material which is to be packaged in the container. The filling may be a continuous length of deformable material which is displaced from the constricted portion of tube during the gathering and constriction of the tube, or it may be spaced apart discrete portions of rigid or dimensionally stable material, the filamentary material being applied around the tube at positions between these portions. The invention is further illustrated by the method of forming containers of the invention which is hereinafter particularly described, by way of example only, with reference to the accompanying drawings wherein

Fig. 1 is a diagrammatic fragmentary side view of a plastics tube filled with a continuous deformable material;
Fig. 2 is a diagrammatic fragmentary side view of a plastics tube containing preformed discrete portions of a filling material;
Fig. 3 shows diagrammatically the tube of Fig. 1 with a cord wound as a ligature around the tube and constricting a portion of the tube;
Fig. 4 shows diagrammatically the tube of Fig. 2 with a cord wound around and constricting portions of the tube intermediate discrete portions of filling material;
Fig. 5 shows diagrammatically the constricted tube of Fi ^g.3 with two adjacent constricted portions cut transversely to separate a sealed filled container from the adjacent tube portions;
Fig. 6 shows diagrammatically the constricted tube of Fig. 4 with two adjacent constricted portions cut transversely to separate a sealed container containing a preformed portion of filling material from the adjacent tube portions. The same numeral is used to denote like elements in all Figs.

Referring to Figs. 1, 3 and 5, the flexible tube 1 is filled with a continuous deformable material 2 and lengths of cord 4 (Fig. 3) are wound tightly in helical manner around longitudinally spaced portions 6 of the tube 1 whereby the portions 6 are gathered together and tube 1 is closed. Adhesive material is applied to the cord lengths 4 whereby the cord lengths 4 are maintained tightly bound in position on the tube portions 6. The tube is then cut transversely at the positions 7, whereby the closed portions 6 and the surrounding cord lengths are divided into two parts 5, each part 5 forming a sealed closure on the tube, the portions of the tube between the adjacent cuts at positions 7 forming individual sealed containers.
The filling material in the plastics tube 1 of Fig. 2 is in preformed portions 3 and, in forming the individual sealed containers, the tube 1 is closed by cord lengths 4 wound around portions 6 and cut at positions 7 as described for Figs. 1, 3 and 5, the portion 6 in this case being intermediate the filling portions 3.
In putting the invention into practice the plastics tube 1 may conveniently be a thin tube of polyethylene, polypropylene or polyvinyl chloride which may be preformed or continuously formed from sheet material during the filling process. The tube may be filled, for example, by continuously pumping or extruding fluent material, or loading discrete portions of filling material into the tube. The filled tube is fed past a closure applying position where, at appropriate intervals, a length of cord is helically wound around the tube to close tube portions 6. Adhesive material is applied to the cord 4 or alternatively to the tube 1, to hold the cord 4 firmly in position. The portion 6 is then cut transversely to divide the two closed portions 6 into two portions 5 and separate a sealed container from the following portion of filled tube 1, each portion 5 sealing an end of a container.
The cord 4 may conveniently be cotton, jute or synthetic plastics string such as is used for conventional parcel binding.
An especially effective and preferred adhesive is cyanoacrylate adhesive, which may be obtained from Loctite (UK) Limited as Loctite (Registered Trade Mark) superfast cyanoacrylate adhesive I.S.--415 or I.S.-495 although, as previously mentioned, hot-meit adhesives are also advantageous. When the adhesives are applied to the cord, this may be done before or after the cord is wound on the tube 1. Alternatively, the tube 1 may be precoated with adhesive before the cord 4 is wound around it. In any case the adhesive will advantageously bond the cord to itself and to the tube 1.

Claims

1. A flexible tubular container having at least one of its ends closed by a length of filamentary material (4) tightly wound in a generally helical manner along a gathered and constricted portion (6) of said end and held in position by adhesive material, characterised in that the container end and the filamentar, material (6) are coterminous and substantially the whole of the end turn of filamentary material lies in the same plane (7) as the container end.

2. A flexible tubular container formed from a continuous length of flexible tube (1) by gathering and constricting said length of tube at 'intervals along its length and binding each constricted portion (6) with a length of filamentary material (4) tightly wound in a generally helical manner along the constricted portion and held in position by adhesive material, characterised in that each constricted tube (6) and length of filamentary material (4) are cut transversely to provide a closed end on each of two containers formed from adjacent portions of the flexible tube (1) with each closed end and substantially the whole of the turn of filamentary material adjacent thereto lying in the same plane (7).

3. A container as claimed in Claim 1 having both its ends closed by a length of filamentary material (4) as specified in Claim 1.

4. A container as claimed in any one of Claims 1 to 3 inclusive characterised in that the filamentary material (4) is adhered both to í_lseif and to the container by an adhesive material which is compatible with the filamentary material and the container.

5. A container as claimed in any one of Claims 1 to 4 inclusive characterised in that the filamentary material (4) comprises cord, tape, string or textile yarn.

6. A container as claimed in any one of Claims 1 to 5 inclusive characterised in that the adhesive material is fast acting.

7. A container as claimed in Claim 6 characterised in that the adhesive material comprises cyanoacrylate adhesive or a hot-melt adhesive.

8. A container as claimed in claim 7 characterised in that the adhesive material comprises a mixture of thermoplastics resin and tackifying resin.

9. A container as claimed in Claim 8 characterised in that the hot-melt adhesive material comprises a mixture of ethylene/vinyl acetate copolymer and rosin ester.

10. A method of making a flexible tubular container from a length of flexible tube (1) which method comprises gathering and constricting a portion (6) of the flexible tube, binding the constricted portion (6) with a length of filamentary material (4) tightly wound in a generally helical manner along the constricted portion of the tube and applying adhesive material to the filamentary material (4) to fix said filamentary material in position on the constricted tube portion, characterised in that the constricted portion (6) of the tube and length of filamentary material (4) are cut transversely to define two closed container ends on adjacent portions of the flexible tube with each closed end and substantially the whole of the turn of filamentary material adjacent thereto lying in the same plane (7).

11. A method as claimed in Claim 10 characterised in that a continuous length of flexible tube (1) is gathered and constricted at each of two spaced apart positions (6), a length of filamentary material is tightly wound in a generally helical manner along each constricted tube portion (6) and fixed thereon with adhesive material and the filamentary material (4) and constricted tube portions (6) are cut transversely at each position to separate a tubular container closed at both ends from the adjacent closed portions of the flexible tube.

12. A method as claimed in Claim 10 or Claim 11 characterised in that the filamentary material (4) is bonded both to itself and to the tubular container.

13. A method as claimed in any one of Claims 10 to 12 inclusive characterised in that the flexible tube (1) is gathered and constricted by the application of the filamentary material (4).

14. A method as claimed in any one of Claims 10 to 13 inclusive characterised in that the adhesive material is applied to the filamentary material (4) as the material is being wound around the tube (1).

15. A method as claimed in any one of Claims 10 to 14 inclusive characterised in that the adhesive material is applied to the filamentary material (4) before the filamentary material is wound around the tube (1).

16. A method as claimed in any one of Claims 10 to 15 inclusive characterised in that the continuous length of flexible tube (1) contains a continuous length of deformable material (2) which is displaced from the constricted portion (6) of the tube during the gathering and constricting of the tube.

17. A method as claimed in any one of Claims 10 to 16 inclusive characterised in that the flexible tube (1) contains discrete portions (3) of rigid or dimensionally stable material and the filamentary material (4) is applied around the tube at positions (6) between these portions.

18. A method as claimed in any one of Claims 10 to 17 inclusive wherein the adhesive material comprises cyanoacrylate adhesive or a hot-melt adhesive.