METHOD FOR PRODUCING A FLEXIBLE POUCH MADE OF FLEXIBLE THERMOPLASTIC MATERIAL

Abstract

A method for producing a flexible pouch made of flexible thermoplastic material, including steps of: (i) preparing hot flexible thermoplastic material in a pasty state, (ii) placing a so-called proximal pre-molded insert onto a mounting such that the insert is arranged in a ring around the mounting, (iii) coating all or part of the insert with hot flexible thermoplastic material in the pasty state, (iv) locking the blow-mold shells around the insert, and (v) injecting a pressurized gas into the chamber so as to expand the sleeve from inside onto the inner surface of the mold or expand the sleeve from the outside by creating negative pressure inside the chamber.

Claims

1-8. (canceled)

9. A method for producing a flexible pouch made of flexible thermoplastic material comprising: (i) preparing said hot flexible thermoplastic material in a pasty state, (ii) placing a pre-moulded insert, or proximal insert, onto a blow pin, mounted in rotation about the longitudinal axis thereof and comprising a blow moulding area, said insert being arranged in a ring around said pin such that the blow moulding area of said pin is downstream from or inside said insert, (iii) coating all or part of said insert with hot flexible thermoplastic material in a pasty state in the form of a parison or a sleeve, (iv) locking the blow-mould shells around said insert so as to form a chamber, said blow pin and said insert being introduced via the bottom of said mould, the distal portion of said pin being at a greater height than the proximal part of said pin and said parison being introduced via the top of said mould, (v) injecting a pressurised gas into said chamber so as to expand the sleeve from the inside onto the inner surface of said mould or expand the sleeve from the outside by creating negative pressure inside said chamber.

10. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 9 wherein the flexible thermoplastic material is a polyurethane.

11. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 9 wherein it uses a second insert, or distal insert, arranged in a ring at the distal end of said blow pin such that said inserts surround said gas injection area.

12. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 9 wherein said sleeve or said parison of hot flexible thermoplastic material in a pasty state coats said blow pin and said insert under the effect of gravity.

13. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 9 wherein said blow pin comprises a plurality of branches each bearing a proximal insert.

14. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 9 wherein at least one of the branches further bears a distal insert.

15. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 13 wherein said branches are mounted movable in translation with respect to one another so as to be able to move away from one another.

16. The method for producing a flexible pouch made of flexible thermoplastic material according to claim 9 wherein said method comprises a filling step, after step (v) or (v) but prior to releasing the mould, where said flexible pouch is filled with a liquid or a gel.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0047] FIGS. 1a-1b show an embodiment of a flexible pouch according to the invention comprising a proximal insert.

[0048] FIGS. 2a-2c show a second embodiment of a flexible pouch according to the invention comprising a proximal insert and a distal insert. FIGS. 2a-2c also show the position of the inserts on the blow pin during the execution of the method according to the invention.

[0049] FIGS. 3a-3d show an embodiment of a flexible pouch according to the invention comprising a plurality of proximal inserts.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

[0050] FIG. 1a shows a side view of a flexible pouch 1 according to the invention and FIG. 1b shows a longitudinal sectional view along the plane A-A of the same pouch. The flexible pouch 1 comprises an insert 2 suitable particularly for use as an access point inside the pouch 1.

[0051] The insert 2 may take any of the forms routinely used in this type of product provided that it includes a longitudinal hole for the passage of the blow pin during the method according to the invention. The blow pin 4 is dimensioned so as extend longitudinally from the upstream of the insert to the free end thereof via said insert. Once the blow pin 4 has been placed in the mould, the free end thereof is ideally placed inside the mould at the end of the wall forming the bottom of the flexible pouch 1.

[0052] The insert 2 may advantageously comprise on the bare proximal portion thereof a threading suitable for engaging with a plug.

[0053] FIG. 2a shows a perspective view of a second embodiment of a flexible pouch 1 according to the invention comprising a proximal insert 2 and a distal insert 3. FIG. 2a also shows a perspective view of the blow pin 4. FIG. 2b shows a side view of said pouch 2 with the pin 4 in position and FIG. 2c a longitudinal sectional view along the plane A-A.

[0054] The proximal insert 2 and the distal insert 3 are placed in a ring around the blow pin 4 which will at the same time enable the positioning of these inserts with respect to the rest of the pouch 1 and also serve to inject gas into the area between the two inserts 2, 3 and enable blow moulding of the flexible thermoplastic material forming the pouch.

[0055] Once in place, the two inserts 2, 3 and the blow pin 4 will be coated with hot flexible thermoplastic material in a pasty state according to the extrusion blow moulding method. Advantageously, the blow pin is arranged such that the distal part thereof is plumb with the proximal part thereof and so as to be introduced into the mould opposite said parison. More specifically, the hot flexible thermoplastic material is extruded via a set of punches and dies preferentially placed plumb with and on either side of the blow pin. This sleeve may have a cross-section of variable shape according to the nature of the pouch to be moulded. Usually, said cross-section may be circular or oval. The hot flexible thermoplastic material sleeve will thereby be suitable for descending by gravity on either side of the blow pin. The ideal flexible thermoplastic material extrusion conditions are well-known to those skilled in the art. Preferentially, the extrusion dies are preferentially set to obtain sleeves of thickness between 0.1 and 10 mm.

[0056] Moreover, the flexible thermoplastic material sleeve is also surrounded by the shells of the mould used to form the pouch.

[0057] The mould used is a conventional extrusion blow moulding mould comprising preferentially two shells comprising cavities intended to form the pouch and the portion thereof to be over-moulded on the surface of the inserts. The mould is preferentially associated with heating means suitable for keeping the shells at a suitable temperature for flexible thermoplastic material blow moulding.

[0058] Once the blow pin 4 and the inserts 2, 3 are surrounded by the flexible thermoplastic material sleeves, the shells of the mould will form a tight chamber around same. The gas is then injected, via the blow pin 4 which will cause the expansion of the flexible thermoplastic material against the walls of the mould.

[0059] This step may be combined with an in-mould labelling method thereby enabling the marking of the pouch simultaneously with the blow moulding thereof.

[0060] The pressure and the quantity of gas injected are adapted to the size and shape of the pouch 1 sought.

[0061] The method according to the invention may also be used to obtain a flexible pouch further comprising one or more inserts to be positioned outside the flexible pouch. In this embodiment, the parison of flexible thermoplastic material will be preferentially over-moulded against the face to be in contact with the insert.

[0062] After formation of the pouch 1, the shells of the mould may be separated and the pouch 1 separated from the blow pin 4.

[0063] The steps described above may be automated and repeated as required.

[0064] It is as such understood that the use of an extrusion-blow moulding/over-moulding method for the production of flexible pouches made of flexible thermoplastic material makes it possible to obtain in a single step a pouch 1 not comprising edges with no material loss.

[0065] FIG. 3a shows a profile view of a further embodiment of a flexible pouch 1 according to the invention comprising a plurality of proximal inserts 2. FIG. 3b shows a front view of the same embodiment, FIG. 3c show a sectional view along the plane 1-1 and FIG. 3d shows an exploded view of said pouch 1.

[0066] The latter type of pouch 1 is obtained using a blow pin 4 comprising a plurality of branches (e.g. assembled in a trident shape), of which at least one comprises an injection area, and suitable for receiving a proximal insert.

[0067] The method according to the invention makes it possible to manufacture pouches for various sectors of activity (medical, pharmaceutical, hygiene, cosmetics, food, etc.) of 3D geometry with particularly the possibility of obtaining fun shapes for children (animals, cartoon characters, flowers, smiley faces, fruit, various objects, etc.).