Extrusion blow molding overmolding process for the production of a flexible two-material or two-color pouch.

Abstract

Extrusion blow molding process for the production of a pouch comprising a neck and a spout of rigid plastic material and a body of flexible thermoplastic material characterized in that it comprises the steps: - [100] preparing said flexible thermoplastic material in a paste-like state, - [200] forming a hollow tubular parison from the material prepared in step [100], - [300] placing a rigid insert forming the spout and shoulder of said pouch on a blow molding support, - [400] casting said parison so that its free end is inside said rigid insert, [500] locking molded shells of a blow mold around said parison and at least a portion of said rigid insert, - [600] expanding the free end of said parison against the inside of said rigid insert,then [700] inject a pressurized gas into said parison so as to expand it internally on the internal surface of said mold or to expand it externally by creating a depression inside said mold, characterized in that during step [600] a section of said parison opposite said free end is not expanded. [Fig. 1],

Description

Title of the invention: Extrusion blow molding overmolding process for the production of a flexible two-material or two-color pouch. technical field

[0001] The present invention relates to a blow molding extrusion process for producing a container comprising a neck and spout made of rigid plastic material and a body made of flexible thermoplastic material. The present invention also relates to the flexible pouches obtained by said process. Previous technique

[0002] Flexible pouches intended to contain liquids are well known in the prior art and are used in particular to transport and store liquids intended for food or medical use.

[0003] Among the bags intended for transporting liquid food, one can notably mention those designed for transporting drinks during sporting activities (also called "camel bags"). However, this use remains limited compared to that of rigid plastic containers (e.g., polyethylene), which are predominant in this field.

[0004] The use of flexible bags is much more widespread in the medical field, where flexibility is particularly important because it allows for zero-volume enclosures (i.e., free of gas and especially ambient air) in the absence of internal liquid. Thus, flexible bags make it possible to maintain the asepsis of the contained products (blood, solutions, medications) throughout their use.

[0005] To date, all flexible pouches, such as medical or food pouches, are manufactured by high-frequency or heat welding from thermoplastic films. More specifically, the pouches are made by welding two layers together, leaving the contents area uncovered. Generally, the films are made of PVC (Polyvinyl chloride) or PP (Polypropylene), and the pouches can have different dimensions to accommodate a content volume between 50 and 1000 ml.

[0006] Current pouches fulfill their main function but all have disadvantages due to both the materials and the manufacturing process.

[0007] The first drawback is related to the mandatory use of plasticizers in the thermoplastic materials used (particularly in the case of PVC). These various plasticizers can tend to migrate into the liquid, which raises significant health problems, particularly when dealing with liquids that are injected or ingested by humans.

[0008] Furthermore, the use of films entails a number of mandatory steps, among which we can notably mention calendering, cutting, flat welding and the final assembly of the pouch obtained with the insert acting as a means of sealing.

[0009] In addition to being time-consuming, these different steps generate product losses related to cutting and the production of troublesome structures such as potentially sharp edges.

[0010] The applicant has developed flexible pouches, described in particular in patent EP3377296, and their production process. These flexible pouches comprise a rigid insert, which forms, for example, the opening of the pouch, around which a parison of a flexible thermoplastic is cast and then formed in a mold by blow molding.

[0011] The present invention therefore aims to provide a method for producing flexible pouches for containing liquids that overcomes the problems raised above. More particularly, said method is more economical and makes it possible to obtain flexible pouches without edges and not necessarily requiring additives such as plasticizers.

[0012] Furthermore, the process according to the invention makes it possible to obtain pouches composed solely of materials that are recyclable in the current recycling stream and with a lower weight than pouches of the prior art. Consequently, the pouches obtained by the process according to the invention have a reduced environmental impact.

[0013] Finally, the process according to the invention makes it possible to obtain pockets with more varied aesthetic characteristics than the pockets of the prior art. The process according to the invention makes it possible to obtain pockets whose rigid part has a different or the same color as that of the flexible part. The process according to the invention also makes it possible to obtain pockets of various shapes and not only cylindrical ones. Summary of the invention

[0014] Thus, the present invention relates to a blow molding extrusion process for the production of a pouch comprising a neck and a spout made of rigid plastic material and a body made of flexible thermoplastic material, characterized in that it comprises the following steps: -

[100] prepare said flexible thermoplastic material in a paste-like state, -

[200] form a hollow tubular parison from the material prepared in step

[100] , -

[300] to place on a blowing support a rigid insert forming the neck and shoulder of said enclosure, -

[400] cast said parison so that its free end is inside said rigid insert,

[500] locking blow mold-impregnated shells around said parison and at least part of said rigid insert, -

[600] expand the free end of said parison against the inside of said rigid insert, then -

[700] injecting a pressurized gas inside said parison so as to expand it internally on the internal surface of said mold or to expand it externally by creating a depression inside said mold, notable in that during step

[600] a section of said parison opposite said free end is not expanded.

[0015] In the context of the present invention, the term "neck" refers to the portion of an enclosure forming the transition between the neck and the rest of the enclosure. Along the neck, the cross-sectional area of ​​the enclosure gradually increases to reach its maximum surface area.

[0016] In the context of the present invention, the term "neck" is intended to designate the portion of the enclosure comprising the opening of the latter.

[0017] In the context of the present invention, the term "rigid" means that the material is slightly deformable under the typical temperature and pressure conditions (20°C, 1 bar) of use of the enclosure according to the invention.

[0018] In the context of the present invention, the term "flexible" means that the material has a Shore 00 hardness of 60 to 100 or a Shore A hardness of 0 to 80.

[0019] In the context of the present invention, the term "rigid" means that the material has a Shore 00 hardness greater than 100 or a Shore A hardness greater than 80.

[0020] In the context of the present invention, the term "shell impression" refers to the various parts of a blow mold. In the context of the present invention, the blow mold extrusion is composed of at least two shells that can be assembled around the insert to form a sealed enclosure into which the parison can be blown.

[0021] In the context of the present invention, the term "parison" refers to a hollow cylinder whose wall is formed from said thermoplastic in a paste-like state. In the field of extrusion blow molding, parisons are well known to those skilled in the art and are conventionally obtained by extruding a paste-like material.

[0022] In the context of the present invention, the term "free end" means the end of the parison furthest from the extruder that formed it.

[0023] According to a preferred embodiment of the invention, said blowing support is a blowing wand, comprising at least a first blowing means, around which said rigid insert is arranged annularily.

[0024] In the context of the present invention, the term "annularly" means that said insert is placed so that its neck is crossed through by said blowing wand.

[0025] According to a preferred embodiment of the invention, at least one first blowing means opens at the end of said cane.

[0026] According to a preferred embodiment of the invention, the flexible thermoplastic material is chosen from the group consisting of polypropylene, polyethylene, polybutene, SEBS, thermoplastic polyurethane and thermoplastic elastomers.

[0027] According to a preferred embodiment of the invention, the flexible thermoplastic material is a recyclable thermoplastic elastomer.

[0028] According to a preferred embodiment of the invention, said rigid insert is made of polypropylene or polyethylene.

[0029] According to a preferred embodiment of the invention, said rigid insert is made of recyclable thermoplastic materials.

[0030] According to a preferred embodiment of the invention, said parison of flexible thermoplastic material in a paste-like state comes inside said rigid insert under the effect of gravity.

[0031] According to a preferred embodiment of the invention, said blowpipe further includes an expansion means capable of expanding the free end of said parison against the inside of said rigid insert.

[0032] According to a preferred embodiment of the invention, said expansion means is at least one finger, associated with said cane, capable of moving from a retracted position to a deployed position where said finger is resting on the free end of said parison.

[0033] According to a preferred embodiment of the invention, said finger is pivotally mounted on the end of said blowing wand.

[0034] According to a preferred embodiment of the invention, said expansion means is at least a second blowing means opening perpendicularly to the longitudinal axis of said blowing wand.

[0035] The present invention also relates to a remarkable pocket in that it is obtained by any one of the processes according to the invention.

[0036] The present invention also relates to a blowing wand, for an extrusion-blowing process according to the invention, comprising a cylindrical body and at least one finger, associated with said wand, capable of moving from a retracted position to a deployed position where said finger extends laterally to the longitudinal axis of said wand.

[0037] The present invention also relates to a blowing wand, for an extrusion-blowing process according to the invention, comprising a cylindrical body and at least one first blowing means opening at its distal end and at least one second blowing means opening perpendicularly to the longitudinal axis of said cylindrical body.

[0038] The blowing wand according to the invention can also be used in an internal or external overmolding process of an insert regardless of the geometry of the latter.

[0039] In the context of the present invention, the term "cylindrical" is not limited to cylinders with a circular cross-section. However, preferably said cylinder has a circular or ovoid cross-section. Brief description of the figures

[0040] [Fig. 1] presents the first step of an embodiment of a process according to the invention implementing pneumatic expansion means.

[0041] [Fig.2] presents the second step of an embodiment of a process according to the invention implementing pneumatic expansion means.

[0042] [Fig.3] presents the third step of an embodiment of a process according to the invention implementing pneumatic expansion means.

[0043] [Fig.4] presents the fourth step of an embodiment of a process according to the invention implementing pneumatic expansion means.

[0044] [Fig. 5] presents the first step of an embodiment of a process according to the invention implementing mechanical expansion means.

[0045] [Fig.6] presents the second step of an embodiment of a process according to the invention implementing mechanical expansion means.

[0046] [Fig.7] presents the third step of an embodiment of a process according to the invention implementing mechanical expansion means.

[0047] [Fig.8] presents the fourth step of an embodiment of a process according to the invention implementing mechanical and pneumatic expansion means.

[0048] [Fig.9] presents the fourth step of an embodiment of a process of overmolding using a cane according to the invention. Detailed description of the invention

[0049] With reference to figures 1-8, two embodiments of the process according to the invention are described below.

[0050] According to a first embodiment shown in Figures 1-4, the expansion of the parison is entirely carried out by at least two gas flows.

[0051] This embodiment uses a blowpipe 1. The latter preferably comprises a substantially cylindrical body 50 extending along a longitudinal axis. Preferably, said blowpipe 1 comprises a distal end 2, intended to be inserted inside a mold 3, and a proximal end 4 intended to remain outside the mold 3.

[0052] The cylindrical body of the blowpipe 1 preferably has a cross-section congruent to the cross-section of the neck 5 of the insert 6, thus allowing the passage of said blowpipe 1 through said neck 5. Said cylindrical portion also preferably has a length at least equal to the height of the neck 5, thus allowing the blowing of a parison 7.

[0053] The blowing wand 1 also includes a first blowing means 8 intended to expand the whole of the parison 7 against the walls of the mold 3. Preferably said first blowing means 8 is a channel 9 adapted to conduct a flow of gas (e.g. air) inside said blowing wand 1 to the outside of the latter at the level of at least a first blowing mouth 10.

[0054] Said first blow nozzle 10 opens preferably at the distal end 2 of the blow rod 1 and is preferably oriented so as to produce a gas flow parallel to the longitudinal axis of the cylindrical body. In so doing, said blow nozzle 10 allows the expansion of the entire parison 7 in the mold 3.

[0055] The blowing wand may include several first blowing outlets 10 each supplied by a different channel 9 or by the same channel 9.

[0056] In this embodiment, the blowing rod 1 includes a second blowing means 11 intended to expand the free end 12 of the parison 7 against the shoulder 13 of the rigid insert 6.

[0057] Preferably said second blowing means 11 is a channel 14 suitable for conducting a flow of gas (e.g. air) inside said blowing wand 1 to the outside of the latter at the level of at least a second blowing outlet 15.

[0058] Said second blow nozzle 15 opens preferably at the lateral wall 16 of the body 50 of the blow rod 1 and is preferably oriented so as to produce a gas flow substantially perpendicular to the longitudinal axis of the body 50. In so doing, said second blow nozzle 15 allows limited expansion at the free end 12 of the parison 7 in the mold 3. It is thus understood that the second blow nozzle 15 is advantageously arranged on the blow rod 1 opposite the shoulder 13 of the rigid insert 6 when the latter is in position on the blow rod 1.

[0059] The blowing wand 1 advantageously comprises several second blowing outlets 15, each supplied by an identical or different channel 14. Preferably, the said second blowing outlet 15 are distributed regularly around the blowing wand 1.

[0060] According to a second embodiment shown in figures 5-8, the expansion of the free end 12 of the parison 7 is entirely achieved by a mechanical means of expansion.

[0061] Similar to the embodiment described above, this embodiment uses a blowpipe 1. The latter preferably comprises a substantially cylindrical body 50 extending along a longitudinal axis. Preferably, said body 50 comprises a distal end 2, intended to be inserted inside a mold 3, and a proximal end 4 intended to remain outside the mold 3.

[0062] The body 50 of the blowpipe 1 also preferably has a cross-section congruent to the cross-section of the neck 5 of the insert 6, thus allowing the passage of said blowpipe 1 through said neck 5. Said body 50 also preferably has a length at least equal to the height of the neck 5, thus allowing the blowing of a parison 7.

[0063] The blowpipe 1 also includes a first blowing means 8 intended to expand the entire parison 7 against the walls of the mold 3. Preferably said first blowing means 8 is a channel 9 adapted to conduct a flow of gas (e.g. air) inside said blowpipe 1 to the outside of the latter at the level of at least a first blowing outlet 10.

[0064] Said first blow nozzle 10 opens preferably at the distal end 2 of the blow rod 1 and is preferably oriented so as to produce a gas flow parallel to the longitudinal axis of the cylindrical body. In so doing, said blow nozzle 10 allows the expansion of the entire parison 7 in the mold 3.

[0065] The blowing wand may include several first blowing outlets 10 each supplied by a different channel 9 or by the same channel 9.

[0066] In this embodiment, the blowpipe 1 includes a mechanical expansion means 17 intended to expand the free end 12 of the parison 7 against the shoulder 13 of the rigid insert 6.

[0067] A person skilled in the art knows how to combine an expansion means 17 suitable for performing the function according to the invention. The embodiment below is only a non-limiting illustration of this more general embodiment.

[0068] Preferably, said mechanical expansion means 17 comprises at least one finger 18, associated with the blow rod 1. The free end 19 of the finger 18 is mounted on the body 50 of the blow rod 1 so as to be able to move away from and towards it up to a deployed position where said free end 19 is in contact with the free end 12 of said parison 7.

[0069] Preferably, said finger 18 is pivotally mounted on the cylindrical body of the blowpipe 1, around a horizontal axis between its folded position and its deployed position.

[0070] The transition from the folded to the extended position can be achieved by any means known to those skilled in the art. According to a preferred embodiment of the invention, the blower wand 1 comprises a rod 20, sliding inside the body 50 between an advanced position and a retracted position. At the end 21 of the rod 20 is positioned the horizontal axis around which the finger 18 pivots. In the advanced position, the end of the rod 20 extends beyond the body 50, allowing the finger 18 to move into the folded position under the effect of gravity. In the retracted position, the rod 20 slides inside the body 50 so that the finger 18 rests on the distal end of said body 50, thus causing it to rotate around the horizontal axis and move into the extended position.

[0071] Preferably, said mechanical expansion means 17 comprises several fingers 18, as described above, distributed around the body 50 of the blow rod 1. Even more preferably, said mechanical expansion means 17 comprises between three and six fingers 18 distributed uniformly around the body 50 of the blow rod 1.

[0072] The invention is not limited to the two embodiments shown in Figs 1-8. It is, for example, also possible to obtain the expansion of the free end 12 of the parison 7 by mixed means combining mechanical expansion means with pneumatic expansion means.

[0073] Regardless of the means of expansion used, the kinematics of the process according to the invention comprise the following steps: -

[100] in which the flexible thermoplastic material is prepared so as to be in the paste-like state.

[0074] In the context of the present invention, the flexible thermoplastic material can be chosen from among all thermoplastics usable in blow molding processes and which remain flexible at room temperature. Preferably, said thermoplastic material is chosen from the group consisting of recyclable flexible polyolefins and elastomers.

[0075] These materials are available, in particular, in granule form and can be made into a paste by heating. During this step

[100] , the flexible thermoplastic material can have additives added to modify its physical and / or aesthetic properties. Thermoplastic elastomers are among these additives.

[0076] This last step can notably be carried out in an extruder whose cylinder and / or screw is maintained at a temperature sufficient to bring the flexible thermoplastic material into a paste-like state. Advantageously, said extruder terminates with an extrusion die enabling the following step to be carried out: -

[200] forming a hollow tubular parison from the material prepared in step

[100] ,

[0077] A person skilled in the art specializing in the field of blow molding is perfectly capable of choosing the die suitable for producing the tubular parison 7 adapted to the production of the enclosure according to the invention.

[0078] According to a particularly preferred embodiment of the invention, said die is arranged so that said tubular parison can descend by gravity into the blow mold.

[0079] -

[300] place on a blowing support a rigid insert 6 forming the neck 5 and shoulder 13 of said enclosure.

[0080] According to a preferred embodiment of the invention, said rigid insert 6 is made of recyclable polyolefin.

[0081] The rigid insert 6 used in the context of the present invention comprises at least one neck 5 and the shoulder 13 of the future enclosure. Said neck 5 is a conventional opening of an enclosure intended to contain a liquid. It may, for example, be a neck having an external thread allowing the insertion of a cap.

[0082] The shoulder 13 corresponds to the area of ​​the future enclosure connecting the neck 5 to the rest of the enclosure. Advantageously, said shoulder 13 has a cross-section increasing from the neck 5 towards its free edge. According to a preferred embodiment of the invention, said shoulder comprises a portion of constant cross-section extending from its free edge 22. This portion is particularly intended to receive the tubular parison on its inner face.

[0083] Preferably, said rigid insert 6 is oriented on the blowpipe 1 so that said neck 5 is below the shoulder 13. Thus, the parison 7 can access the inside of the insert 6 by gravity.

[0084] The blowing support allows the rigid insert 6 to be held in position during the blowing step. Preferably, this blowing support is a blowing tube 1 as described above. The body 50 of the tube 1 is designed to fit into the neck 5 and thus prevent lateral movement of the rigid insert 6. Preferably, the base of the blowing tube 1 is positioned on a platform 23 extending perpendicularly to the longitudinal axis of the tube 1 and designed to limit the movement of the insert 6 along the longitudinal axis of the tube 1.

[0085] -

[400] cast said parison 7 so that its free end 12 is at the interior of said rigid insert 6.

[0086] Preferably, the parison 7 flows by gravity from the extruder die to the inside of the rigid insert 6. According to an even more preferred embodiment, the invention implements a means for detecting the position of the free end 12 of the parison 7. This means makes it possible to determine whether the parison 7 has descended sufficiently to cover the entire mold and the inside of the shoulder 13 of the rigid insert 6.

[0087] Said means for detecting the position of the free end 12 of the parison 7 can take various forms. Among these, we can notably mention those based on mechanical or optical detectors.

[0088] Once the end 12 of the parison 7 is inside the rigid insert 13, either step

[500] or

[600] can be carried out interchangeably. According to a preferred embodiment of the invention, step

[500] is carried out before step

[600] .

[0089]

[500] lock imprinted shells of a blow mold around said paraison 7 and at least a part of said rigid insert 6.

[0090] The mold shells used in the process according to the invention are conventional mold shells for blow molding extrusion. These shells can fully or partially cover the rigid insert 6 once they are locked in place. Advantageously, these shells fully cover the walls of the rigid insert 6 once locked in place.

[0091] Conventionally, the mold used in the process according to the invention comprises two impression shells. However, a mold comprising more than two impression shells can also be envisaged.

[0092] -

[600] expand the free end 12 of said parison 7 against the interior of said rigid insert 6.

[0093] During this step, only the portion of the parison 7 intended to be in contact with the rigid insert 6 is expanded by the expansion means. The remainder of the parison 7 is subsequently expanded against the mold wall during the following step: 1700] injecting a pressurized gas inside said parison 7 so as to expand it from the inside on the internal surface of said mold or to expand it from the outside by creating a depression inside said mold. The successive sequence between steps

[600] and

[700] ensures a perfect seal between the parison 7 and the insert 6 and thus makes it possible to obtain an enclosure of superior quality to those of the prior art.

[0094] As illustrated in [Fig. 9], the blowpipe according to the invention can also be used in processes other than the process according to the invention. In particular, the blowpipe according to the invention can be used in overmolding processes.

Claims

Demands

1. Blow molding extrusion method for producing a pouch comprising a neck (13) and a spout (5) of rigid plastic material and a body of flexible thermoplastic material characterized in that it comprises the steps: - [100] preparing said flexible thermoplastic material in a paste-like state, - [200] forming a hollow tubular parison (7) from the material prepared in step [100], - [300] placing on a blow molding support (1) a rigid insert (6) forming the spout (5) and the shoulder (13) of said pouch, - [400] casting said parison (7) so that its free end (12) is inside said rigid insert (6), [500] locking molded shells of a blow mold around said parison (7) and at least a portion of said rigid insert (6), - [600] expanding the free end (12) of said paraison (7) against the inside of said rigid insert (6),then - [700] inject a pressurized gas inside said parison (7) so as to expand it internally on the internal surface of said mold or to expand it externally by creating a depression inside said mold, characterized in that during step [600] a section of said parison (7) opposite said free end (12) is not expanded.

2. Blow molding extrusion method for the production of a bag according to claim 1 characterized in that said blowing support (1) is a blowing wand (1) comprising at least a first blowing means (8) and in that said rigid insert (6) is arranged annularly around said wand (1).

3. Blow extrusion method for the production of a bag according to the preceding claim characterized in that at least a first blowing means (8) opens at the end (2) of said rod (1).

4. Blow molding extrusion process for producing a pouch according to any one of the preceding claims, characterized in that the flexible thermoplastic material is a polyurethane selected from the group consisting of polypropylene, polyethylene, polybutene, SEBS, thermoplastic polyurethane and thermoplastic elastomers.

5. Blow molding extrusion process for the production of a pouch according to any one of the preceding claims characterized in that said rigid insert is made of polypropylene, polyethylene or recyclable thermoplastic materials.

6. Blow molding extrusion method for the production of a pouch according to any one of the preceding claims characterized in that said parison (7) of hot, flexible thermoplastic material in a paste-like state comes inside said rigid insert (6) under the effect of gravity.

7. Blow extrusion method for the production of a bag according to any one of the preceding claims characterized in that said blow wand (1) further comprises an expansion means capable of expanding the free end (12) of said parison (7) against the inside of said rigid insert (6).

8. Blow molding extrusion method for the production of a bag according to the preceding claim characterized in that said expansion means is at least one finger (18), associated with said rod (1), capable of moving from a retracted position to an extended position where said finger (18) is resting on the free end (12) of said parison (7).

9. Blow extrusion method for the production of a bag according to the preceding claim characterized in that said finger (18) is pivotally mounted on the end of said blow wand (1).

10. Blow molding extrusion method for the production of a bag according to claim 7 characterized in that said expansion means is at least a second blowing means (11) opening perpendicularly to the longitudinal axis of the blowing wand (1).

11. Blowing wand (1), for an extrusion-blowing process according to any one of the preceding claims, comprising a cylindrical body (50) including at least one finger (18), associated with said wand (1), capable of moving from a retracted position to an extended position where said finger (18) extends laterally to the longitudinal axis of said wand (1).

12. Blow molding wand (1), for an extrusion blow molding process according to any one of claims 1 to 10, comprising a cylindrical body (50) including a first blowing means (8) opening at its distal end (2) and at least a second means of blowing (11) opening perpendicularly to the longitudinal axis of said body (50).

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