GB2368059A

GB2368059A - Shoulder member for a flexible tubular container

Info

Publication number: GB2368059A
Application number: GB0025375A
Authority: GB
Inventors: Michael David Prosser
Original assignee: Arista Tubes Ltd
Current assignee: Arista Tubes Ltd
Priority date: 2000-10-17
Filing date: 2000-10-17
Publication date: 2002-04-24
Anticipated expiration: 2020-10-17
Also published as: GB2368059B; GB0025375D0

Abstract

A thermoplastic shoulder member for a flexible thermoplastic tube container has a nozzle (13) with an orifice (14) therein, and is compression moulded to form on the internal side of the orifice (14) a surrounding inwardly projecting hollow spigot (21) which is formed by back extrusion during compression moulding. The shoulder member (12) may be formed from a laminate material which includes a barrier layer (23) which extends into the inwardly projecting spigot.

Description

Tubular Container and Method of manufacture thereof Field This invention relates to flexible tubular containers of the type used for packaging and to a method of manufacture of such tubes.

Background of the Invention Flexible thermoplastic tube containers are extensively used for packaging of cosmetics, toothpaste, foodstuffs, shampoos and the like for storage and distribution. A typical container is formed from an extruded cylindrical body having a shoulder member at one end with a closure attached thereto to seal that end of the tube. The other end remains open until the tube is filled with its respective contents and is then closed by means of heat sealing clamped together opposed inner surfaces of the tube to form a"fish tail"type end.

It is becoming fashionable for such flexible containers to have the shoulder member fitted with a closure having a flat lid allowing the container to stood on its lid. If the contents of the tube comprise a paste suspended in a liquid matrix, for example food pastes which may be suspended in oil, vinegar, or water, then some of the liquid may partially separate from the paste.

Object of the Invention The present invention provides a tube shoulder in which some separated liquid can be accumulated without being expelled from a tubular container on use, and a method of manufacture.

Statements of Invention According to a first aspect of the present invention there is provided a thermoplastic shoulder member for a flexible thermoplastic tube, the shoulder member being a compression moulding and having a nozzle with an orifice therein, the internal side of the orifice being surrounded by an inwardly projecting spigot which is formed by back extrusion during the moulding process.

When the contents of the tube container include volatile substances e. g toothpaste, the tubular body is typically formed from a multilayer laminate which includes a barrier layer resistant to gaseous diffusion to retain the volatile matter within the container. The tube shoulder member may likewise have improved resistance to vapour transmission. Such tube containers are also useful when the contents of the container are reactive with atmospheric gases and it is desired to prevent diffusion of gases into the container.

Preferably the shoulder is formed from a laminate material

which includes a barrier layer and the barrier layer extends into the inwardly projecting spigot. The spigot extends inwardly for at least about one half of the depth of the nozzle, typically 4.5mm and preferably for between 5-10mm.

Also according to the present invention there is provided a thermoplastic shoulder member for a flexible thermoplastic tube container, the shoulder member being formed of a laminate material including a barrier layer and having a nozzle with an orifice therein, the internal side of the orifice being surrounded by an inwardly projecting spigot and the barrier layer extends into the spigot.

The laminate typically comprises outer layers of a polyolefin, or mixture of olefins, e. g linear low density polyethylene and high density polyethylene, with a barrier layer e. g ethylene vinyl alcohol, sandwiched therebetween. A tie layer is used to secure the two outer layers to the barrier layer.

Yet another aspect of the invention provides a flexible thermoplastic tubular container having a shoulder member at one end thereof with a closure secured to the shoulder member, said closure having a flat surface whereby the container can be stood upright on said closure, wherein the shoulder member

is as described above.

Also according to the present invention there is provided a method of forming a container comprising a flexible tubular body with a shoulder member located at one end of the body, said method comprising compression moulding molten thermoplastic material directly onto said tube to form a shoulder member having a nozzle with an aperture therein, wherein during the moulding process material is back extruded to form within the nozzle an internally projecting hollow spigot around the aperture.

US patent 3047 910 describes a process for the manufacture of a tubular container in which the tubular body is placed in a forming collar and a separate molten disc of thermoplastic material is forced into the open end of the body while it is retained by the collar. The latent heat of the molten disc welds its periphery to the inner surface of body to form an end wall. Pressure is then applied in one direction to the welded end wall to shape the wall to form a shoulder member of a desired shape which typically includes a nozzle having an orifice therein.

Preferably the spigot is formed by back extrusion in the reverse direction to the applied pressure during the shaping of the shoulder member.

Preferably, the thermoplastic material is in the form of a laminate disc including a barrier layer, the barrier layer being back extruded into the spigot.

A membrane closure may be attached to the nozzle to seal the orifice, and the nozzle may be provided with a hinged closure.

Description of the drawings The invention will be described by way of example and with reference to the accompanying drawings in which: Fig. 1 is a side elevation of a container according to the present invention, Fig. 2 is a section through the nozzle of the container shown in Fig 1, Fig. 3 is a section through the container shown in Fig. l with a closure fitted thereto, and Fig. 4 is a section through apparatus for forming a container according to the present invention, Detailed Description of the Invention With reference to Figs. 1 & 2, there is shown a thermoplastic flexible tubular container 10 formed in accordance with a method described in US 3047 910.

The container 10 has a flexible tubular body 11 formed from extruded thermoplastic material with a thermoplastic shoulder

member 12 welded to one end of the body 11. The shoulder member 12 includes frustoconical portion 17 having a coaxial nozzle 13 with an orifice 14 therein for discharge of any contents from the container. The nozzle 13 is formed with an external screw thread 15 for connection to a closure 30 (see Fig. 3). The orifice 14 may be sealed by a membrane 16. The container 10 is filled with contents at its other end which is sealed after filling by a heat seal 18 forming a"fish tail" at that end of the container.

With reference also to Fig. 3, the closure 30 comprises a cylindrical body 31 which has an end wall 37 with a discharge aperture therein which aligns with the orifice 14. An outer skirt 32 and inner skirt 33 project axially away from the end wall 37 and a lid 34 is pivotally connected to the body by a hinge 35 to close the aperture.

The hinged lid 34 has a substantially flat end face 40 so that when the lid is in a closed condition, as shown, the container 10 may be stood upright on a surface S. When in this condition, the contents of the container may separate out.

This is especially so for food stuffs in the form of pastes and sauces when small volumes of the liquid matrix may over a period of time gather in the bottom of the container i. e towards the closure 30. In order to retain the separated out liquid within the container, especially on discharge of the

contents after a period of non-use, the nozzle 13 is provided with an internally projecting hollow spigot 21 which surround the orifice 14. The internal surface of the spigot 21 is substantially in alignment with the edge of the orifice to maximise the capacity of the reservoir 22 formed between the spigot 21 and the internal surface 19 of the nozzle 13. The height H of the spigot is preferably about one half of the depth of the nozzle, preferably about 4.5-6. 0 mm for a container having a capacity of about 220 ml and a nominal 20mm dia nozzle having a depth of about 10mm.

The closure 30 is secured to the nozzle 13 by an internal screw thread 36 on the inner skirt which cooperates with the thread 15 on the nozzle. Alternatively, the closure 30 may be secured to the nozzle 13 by other suitable inter connecting devices e. g. a snap fit connection.

The body 11 and shoulder member 12 are preferably formed from laminate material which includes a barrier layer to reduce transmission of gases and vapours into and out of the container. Typical laminate material for the body 11 has an overall thickness of between 360-550 microns and comprises a thin barrier layer (about 25-35 microns) sandwiched between two relatively thick layers (125-300 microns) of polyolefin material (s) with tie layers therebetween. The polyolefin material is typically a mixture of high density polyethylene

and linear low density polyethylene.

The shoulder member 12 may be formed from the same laminate as the body 11 or preferably a different thicker laminate having an overall thickness of between 1140-1650 microns. The laminate has a substantially thick outer polyolefin layer (950-1300 microns), that is outer with respect to the container and which comprises low density polyethylene. The thicker material and use of low density material allows for better forming of the shoulder member 12 during the processing. The shoulder member 12 is formed so that the barrier layer 23 extends into the spigot 21.

With reference to Fig 4, the container 10 is formed from extruded tube 11 having a molten disc 12A, at a temperature of about 220 degrees centigrade, forced into an open end of the tube as is described in US Patent 3047 910 (Downs). The tube 11 and disc 12A is loaded onto a mandril 61 for shaping within a female mould 62 using compression moulding at a final load of about 100 bar (about 1500 psi). The mandril 61 will have a operating temperature of about 60-70 degrees centigrade and the mould 62 is water cooled using water having a temperature of about 4 degrees centigrade. The mandril 61 has a tip 64 with a front face 65 which has a coaxial annular groove 66 formed therein. The groove 66 in use forms the hollow spigot 21 and has a depth of about 6mm and a width of about 0. 7mm at

its innermost end, the wall having a draft angle of about 3 degrees of arc to aid removal from the mandril after moulding.

The mould 62 has a tapered"lead in"portion 67 to feed the end portion of the tube 11 an annular collar 68 connected to an frustoconical portion 69. A co-axial nozzle mould portion 71 is located below the frustoconical portion 69.

The front face 65 of the mandril contacts the central portion of disc 12A and as the mandril 61 moves into the mould 62 feeding the tube 11 into the collar 68 until the outer peripheral edge of the disc abuts the outer margin of the conical portion 69 of the mould. Further inwards movement of the mandril 61 causes the centre of the disc to move further into the mould forming the frustconical portion 17 of the shoulder against the surface 69, and moving the disc 12A into contact with a spring loaded pin 63. Further movement forces the pin through the disc 12A forming the orifice 14.

Further inward movement of the mandril 61 forces material into the nozzle portion 71 of the mould. As the mandril fully closes to form the nozzle, material is back extruded into the groove 66 on the front face 65 of the mandril.

The thermoplastic material of the disc 12A is cooling

throughout the process and has a predetermined maximum thickness set by the thickness of the laminate. It is surprising within this context of the process that sufficient material can be back extruded into the groove to form a spigot of up to half the depth of the nozzle. It is even more surprising that the back extruded material retains its laminate structure with the barrier layer remaining a distinct layer within the spigot.

Claims

Claims 1. A thermoplastic shoulder member for a flexible thermoplastic tube container, the shoulder member being a compression moulding and having a nozzle with an orifice therein, the internal side of the orifice being surrounded by an inwardly projecting hollow spigot which is formed by back extrusion.
2. A shoulder member as claimed in Claim 1 wherein the shoulder is formed from a laminate material which includes a barrier layer and the barrier layer extends into the inwardly projecting spigot.
3. A thermoplastic shoulder member for a flexible thermoplastic tube container, the shoulder member being formed of a laminate material including a barrier layer and having a nozzle with an orifice therein, the internal side of the orifice being surrounded by an inwardly projecting hollow spigot and the barrier layer extends into the spigot.
4. A shoulder member as Claimed in any one of Claims 1 to 3, wherein the spigot has a length of at least 4.5mm.
5. A shoulder member as claimed in any one of Claims 1 to 4 wherein the spigot has a length of at least about half of the depth of the nozzle.
6. A shoulder member as claimed in Claim 4 or Claim 5 wherein the internal walls of the spigot are substantially aligned with the edges of the aperture.
7. A flexible thermoplastic tubular container having a shoulder member secured thereto at one end thereof with a closure secured to the shoulder member said closure having a flat surface whereby the container can be stood upright on said closure wherein the shoulder member is as claimed in any one of Claims 1 to 7.
8. A flexible tube container as claimed in Claim 7, wherein the container further includes a cylindrical body formed from a laminate material.
9. A method of forming a container comprising a flexible tubular body with a shoulder member located at one end of the body said method comprising compression moulding molten thermoplastic material to form directly onto said tube a shoulder member having a nozzle with an aperture therein, wherein during the moulding process material is back extruded to form within the nozzle an internally projecting hollow spigot around the aperture.
10. A method as claimed in Claim 9 wherein the molten

thermoplastic material is in the form of a disc and the latent heat in the disc welds its periphery edge to the inner surface of the tubular body, pressure being applied to the hot disc by movement of a mandril in one direction to form the shoulder member causing material to extrude in the reverse direction to form the spigot.
11. A method as claimed in Claim 10 wherein the disc is a laminate of predetermined thickness which contains a barrier layer and the barrier layer is extruded into the spigot.
12. A method as claimed in Claim 10 or Claim 11, wherein the mandril has a tip which contacts only the central portion of the disc, the tip having a groove therein into which the laminate material back extrudes during only the final stages of shaping.
13. Apparatus for compression moulding a shoulder member of flexible tubular container by a method as claimed in any one of Claims 9 to 12, the apparatus includes a mandril which accomodates the tubular body and has a tip for forming a nozzle, the tip having a front face with a coaxial annular groove formed therein for back extrusion of the thermoplastic material to form a hollow spigot.