Technical Field

The present invention relates to a barrier container, in particular a tube, and a barrier container laminate for manufacturing same. Such container and preferably such laminate can be recycled as such within existing mono-material recycling streams, i.e. without demanding technically challenging and costly material separation.

Background Art

Flexible containers, such as collapsible tubes, for substances such as pastes, jellies, emulsions, liquids, foams, powders, etc ., with barrier effect, i.e. that are at least partially gas-tight, such as air-tight, and liquid tight, and their production have been heretofore described. For example US 3,660,194 discloses a method of producing gas-tight and liquid-tight containers, especially collapsible tubes, wherein a stripe of plastic coated carrier foil, a tube laminate, is bent or wound into the shape of a substantially cylindrical tube, the longitudinal edges of the stripe being arranged in overlapping relationship to form a tube-like body. These longitudinal edges are then heat-sealed and coated with a sheath of plastic to form the tube body. The sheath of plastic covers the overlapping seams and provides a smooth continuous outer surface capable of receiving an imprint. Further, according to this document the amount of plastic material and application thereof to the surface of the tube-like body is controlled such that the outside surface of such tube body, when covered with the plastic sheathing possesses a shape and dimension substantially corresponding to the internal receiving wall of a mold cavity for heading the tube. The tube body, typically after having been cut into finite tube sec- tions, is then inserted at one end into a mold cavity, the outside surface of such tube section snugly fitting in good sealing relationship against the internal receiving wall of the mold cavity. The inner wall of the tube section, at least at the end region thereof received in the mold cavity is freely exposed, so that when moldable material is introduced into the mold cavity it contacts such exposed inner wall, thereby producing a substantially radially directed force applied outwardly against the inner exposed wall of the tube body, urging the outer wall thereof into extreme sealing contact with the internal receiving wall of the mold cavity so that an extremely effective seal appears at the location where the tube section has been inserted into the molding cavity.

Also the container described in WO 2010/135843 comprises a container body formed of a tube laminate, said tube laminate having an at least partially fluid-tight carrier foil sandwiched between thermoplastic semi-rigid or rigid layer material. This tube laminate is folded to a container-like body and sealed in the overlapping edge regions to stabilize the container-like body. This container-like body is then coated with a sheathing of elastomeric thermoplastic material of the same kind or type as the foil material to form a container body that is provided at one open end with a container head formed from thermoplastic material of the same kind or type as the foil material.

All these former container comprise a laminate with a barrier layer, in particular a barrier layer- made of aluminum, SiOx, AlxOy, ethyl vinyl alcohols (EVOH), cycloolefin copolymers (COC) and polyamide (PA). Best fluid-tightness is obtained with metal foils. These laminates or tubes, respectively, are not suitable for being recycled without laborious material separation. Therefore there is still a need for tubes and laminates for their production that are easily recyclable.

Abbreviations:

PE = polyethylene

LLDPE = linear low density polyethylene

0.915-0.925 g/cm ³

LDPE = low density polyethylene 0.910- 0.940 g/cm ³

HDPE = high density polyethylene ³0.941 g/cm ³ MDPE = medium density polyethylene 0.926-

0.940 g/cm ³

PP = polypropylene

EVOH = ethylene vinyl alcohol copolymer PVOH = polyvinyl alcohol PA = polyamide

PET = polyethylene terephthalate

PVC = polyvinyl chloride

PVDC = polyvinylidene chloride

OTR = oxygen transmission rate

MDO = mono-axial / mono-directional oriented OPP = oriented polypropylene SF = solvent-free PE-met = metallized PE foil OPP-met = metallized OPP foil AlxOy = aluminum oxide SiOx = silicon oxide

Definitions :

Container laminate, in particular tube laminate: foil suitable for the production of collapsible containers like tubes comprising a barrier layer laminated to a polyolefin foil on each of its sides.

Container body or tube body: container / tube like part without shoulder/head.

Collapsible container or tube: the final container with container or tube body and shoulder/head without closure. The collapsible container, especially tube, can have an open end for being filled opposite of the shoulder/head or it can be filled and - if filled via an open end - said open end sealed.

Barrier layer: encompasses all types of barrier foils optionally provided with one or more functional layers.

Barrier foil: an oriented plastics foil composed of one or more polymeric materials.

Monolayer foil: a barrier foil with one polymer layer only such as an OPP-foil.

Coextruded foil: a barrier foil composed of different polymeric materials such as MDO-PE-foil with intermediate EVOH-layer.

Barrier foil laminate: laminate of two or more barrier foils, said barrier foils optionally comprising one or more functional layers on at least one of their surfaces.

Functionalized barrier foils: a monolayer barrier foil or a coextruded barrier foil or a barrier foil laminate comprising one of more functional layers on at least one of its surfaces in the case of monolayer foils and coextruded foils or one or more functional layers on at least one of its surfaces and/or one or more intermediate functional layers in case of barrier foil laminates.

Polyolefin of the same type or kind: polyolefin composed of the same monomer units, i.e. polyethylene, polypropylene, polybutylene etc. PEs of different densities such as LLDPE, LDPE, MDPE, HDPE are considered the same type or kind of PE as far as the recyclability in mono-material recycling streams is concerned.

Disclosure of the Invention

Hence, it is a general object of the invention to provide a preferably gas-tight, such as airtight, and liquid-tight collapsible container, especially a collapsible tube, that is made of thermoplastic material and that can be recycled in mono-material recycling streams without any separation step involved.

It is another object of the invention to provide a container body, especially a tube body, of a container such as a tube and/or a container laminate suitable for producing such a container / tube.

Now, in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the collapsible container is manifested by the features that it comprises a container body formed of a container laminate, said container laminate being folded to a con- tainer-like body and sealed in the overlapping edge regions, said container-like body having an outer surface coated with a sheathing of polyolefin material to form the container body, said container body being provided at one open end with a shoulder/head formed from polyolefin material, wherein said container laminate is a laminate having at least three layers, an inner polyolefin layer and an outer polyolefin layer and a barrier layer sandwiched between the outer polyolefin layer and the inner polyolefin layer, wherein the barrier layer comprises at least one oriented polyolefin comprising barrier foil and wherein at least 90 % by weight of the container are made of a polyolefin of the same kind.

In a preferred embodiment, the inside of the container that upon use is in contact with the filled-in goods has an inert surface.

The barrier layer makes the collapsible container air-tight and liquid-tight (further on referred to as fluid-tight), allowing for shelf-life extension of packed goods. In order to obtain an increased fluidtightness, the barrier foil comprised in the barrier layer can be provided with one or more functional layer (s) on at least one of its surfaces. Such functional layers are metal layers, metal oxide layers, ceramic lay- ers and barrier lacquer layers. In order to reduce the risk that the container content might come into contact with e.g. the metallization or the metal oxide layer of a functionalized barrier foil even when, for instance, the polyolefin layer applied to the barrier foil is defective or, for instance, contains pores or openings, or in order to further improve the air-tightness of the barrier foil it can be desirable to provide the barrier foil with a barrier lacquer between the side of the container laminate forming the inner side of the container body and the metal or metal oxide layer. Such lacquer can e.g. be on the same side of the barrier foil or on the opposed side.

For the desired recyclability the container body has to be of polyolefin of the same kind in an amount of at least 90 weight-%, preferably at least 95 weight-% referred to the weight of the container and preferably of the container body. Further recommendations for good recyclability are:

In a preferred embodiment the container laminate itself already meets the above indicated criteria, i.e. at least 90 weight-%, preferably at least 95 weight- % referred to the weight of the container laminate of a polyolefin of the same kind.

The barrier foils are oriented foils based on polyolefins. Dependent on the demanded fluid-tightness, different embodiments of the barrier layer are preferred. The polyolefin comprising and oriented barrier foil can be a monolayer foil or a coextruded foil comprising at least two different materials. The polyolefin comprising barrier foil can be provided with a metal layer or a metal oxide layer or a ceramic layer on one or both sides and/or with a barrier lacquer layer. In case of critical content of a tube, such as in case of pharmaceuticals, it is preferred that a possible metal or metal oxide layer is on the side of the barrier foil directed towards the outside of the tube body and therefore it is preferred to have a barrier lacquer applied on the inner side of the barrier foil or on the outer side between the barrier foil and the metal or metal oxide layer, although for other applications a sequence "polyolefin comprising barrier foil - metallization or metal oxide or ceramic layer - barrier lacquer" may be preferred. Such optionally functionalized barrier foils can be the barrier layer in the container laminate.

In an alternative embodiment two or more optionally functionalized barrier foils of the same or different type can be laminated by means of an adhesive to form a barrier foil laminate used as barrier layer in a container laminate.

The barrier layer can be a polyolefin comprising barrier foil, such as a polyolefin monolayer foil or a polymeric coextruded foil, or a barrier foil laminate composed of two or more barrier foils of same or different kind. The polyolefin comprising and oriented barrier foil can optionally also be provided with a functional layer, be it used as such or in a barrier foil laminate.

Some embodiments of such barrier layers are further detailed below:

- barrier foil - metal or metal oxide or ceramic layer

- barrier foil - barrier lacquer

- barrier foil - barrier lacquer - metal or metal oxide or ceramic layer

- barrier foil - metal or metal oxide or ceramic layer - adhesive layer - barrier foil - metal or metal oxide or ceramic layer

- barrier foil - barrier lacquer - metal or metal oxide or ceramic layer- adhesive layer - barrier foil - metal or metal oxide or ceramic layer

In the scope of the present invention, presently PE containers such as PE tubes are preferred.

A presently preferred monolayer foil is a mono-axial, also termed mono-directional, oriented (MDO) PE foil. Such foils are commercially available. In general such foils are produced in that, during the orientation process, a blown film is stretched between two rollers which run at different speeds.

MDO foils are ideally produced from LLDPE, optionally from a mixture of LLDPE and HDPE.

An alternative foil is an oriented PP (OPP) foil. An OPP-foil in case of PE-tubes has the disadvantage that it is limited in thickness due to the demand that at least 90 % of the container must be PE.

An advantage of OPP-foils is their commercial availability, e.g. from Jindal Films or Toppan. The disadvantage is that their thickness is limited in order to guarantee the limit of £ 10 %. For PE-tubes with a OPP- foil sandwiched between two PE-foils of e.g. 70 mm a thickness of the OPP-foil of 16 to at most 20 mm in case of a PE-sheathing of ³ 40 mm is acceptable.

A presently preferred coextruded foil is e.g. a MDO-PE-EVOH-foil with an EVOH layer between two PE- layers. Such material has an improved air-tightness compared to a pure MDO material of the same thickness.

Such MDO foil with additional central barrier can be produced starting from a 5 layer co-extruded blown foil having the layers PE/tie/EVOH/tie/PE, wherein the tie layer is a modified polyolefin with functional groups, designed to bond to a variety of polyolefins, e.g. a maleic anhydride grafted LLDPE material. Said tie is applied in a thickness of 5-10 mm. In general an e.g. 60-100 mm blown foil is produced that directly after the blowing process is unidirectionally (monodirectionally) stretched. The stretching factor in general is 3 to 5. In case of a 60 mm foil stretched with a factor 3, a 20 mm MDO foil is obtained. By this process, the resulting EVOH barrier layer has a thickness of only about 1 to 3 mm which keeps the amount of non-PE materials very low with a nevertheless good air-barrier effect. This good barrier effect is i.a. due to the enhanced crystallinity of the materials due to the orientation of the MDO foil. Measurements of the barrier effect gave an OTR of approx. 10 ml/ (m ² x d x bar) measured at 23°C/50%r.h. Compared to a not stretched PE foil without EVOH barrier (approx. 5000 ml/ (m ² x d x bar)) this is a significant improvement.

A much preferred metal layer for metallization is aluminium and preferred metal oxides are silicon oxides (SiOx) and aluminium oxides (AlxOy). A suitable thickness of a metallization, i.e. for obtaining a good barrier, is about 20-50 nm.

Suitable barrier lacquers are e.g. PVOH based, preferably lacquers with PVOH as sole polymer.

PVOH lacquers are usually applied in amounts resulting in a final (cured) weight of 1 to 3 g/m ² , or a thickness of about 1 to 3 mm, preferably 1 to 2 g/m ² , or a thickness of about 1 to 2 mm, such as about 1 g/m ² , or a thickness of about 1 mm.

Presently preferred polyolefin comprising barrier foils are commercially available, such as

- OPP-foils, preferably in a thickness of 16 to 20 mm, on one side provided with an AlxOy or SiOx or metal, like aluminium, layer or thin film coating, respectively.

A barrier foil laminate can be obtained by laminating two or more barrier foils by means of an adhesive. In general two monolayer foils are laminated such as two OPP-foils, two MDO-PE-foils, or one MDO-PE-foil and one OPP-foil, or two coextruded foils like two MDO- PE-EVOH foils or one MDO-PE-EVOH foil with one MDO-PE- foil or one OPP-foil, wherein all barrier foils can be provided with one or more functional layer(s).

An example of a functionalized barrier foil laminate is composed of an OPP-foil with an AlxOy or SiOx layer on one side and an OPP-foil with a metal layer on one side, said foils being laminated together with an adhesive. Suitable adhesives are polyurethane based, preferably solvent-free or water-based, respectively, adhesives. Such adhesives are preferably applied in an amount (dry weight) of 1 to 3 g/m ² or about 1 to 3 mm such as about 1.5 g/m ² or about 1.5 mm.

The same adhesive in the same thickness range can also be used to laminate the barrier layer between two polyolefin foils. Preferred polyolefin foils are PE- foils formed in an extrusion blow-molding process. De- pendent on the intended use of the tube container, at least the inner foil may be pharmaceutical grade polyolefin, preferably pharmaceutical grade PE.

A preferred material for the flexible outside foil is LDPE, although LLDPE and MDPE types can also be used as well as mixtures of HDPE and LLDPE.

For the sealable inside foil a mixture of LLDPE and HDPE or pure MDPE are ideally used. LDPE is less suitable since it results in a seal of limited strength. A very good sealable mixture comprises 70% LLDPE and 30 % HDPE and optionally antiblock additives, being added as PE based masterbatches containing inert SiOa beads in the range of 5 mm in diameter.

In another embodiment the inner and the outer side of the container laminate can be made of MDPE.

Suitable container laminates have the following structure polyolefin foil - adhesive - barrier layer composed of one or more optionally functionalized barrier foils adhesive - polyolefin foil.

Presently preferred polyolefin foils are PE- foils in particular PE-foils with a thickness of approx. 70 mm.

The shoulder/head of the tube container is made of PE if the polyolefin foils are PE based and of PP if the polyolefin foils are PP based. In case of PE, HDPE is a preferred shoulder/head material. It is preferred to have PP closures for PP containers and PE closures for PE containers.

A method suitable and preferred for manufacturing fluid-tight containers or tubes of the present in- vention is essentially described in US 3,660,194 that is incorporated herein by reference in its entirety. Said method has already been outlined in the state of the art chapter above.

Brief Description of the Drawings

The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings showing schematic sectional view through a tube foil or tube laminate, respectively, formed from the indicated foils (from inside to outside with a slash indicating an adhesive layer) wherein:

Fig. 1 is an enlarged fragmentary sectional view of the container or tube body prior to the heading thereof, and wherein the thickness of the various layers of the tube have been exaggerated appreciably for the purpose of clarity and simplification in explanation of the invention.

FIG. 2 is PE / MDO-PE+metallization (or metal oxide or ceramic) / PE.

Fig. 3 is PE / MDO-PE+lacquer+metallization (or metal oxide or ceramic) / PE.

FIG. 4 is PE / MDO-PE-EVOH+metallization (or metal oxide or ceramic) / PE.

Fig. 5 is PE / MDO-PE-EVOH+lacquer+ metallization (or metal oxide or ceramic layer) / PE.

FIG. 6 is PE / OPP+AlxOy / PE.

Fig. 7 is PE / OPP+metallization / PE. FIG. 8 is PE / OPP+metallization (or metal oxide or ceramic) / OPP+metal oxide or ceramic (or metallization) / PE.

Fig. 9 is PE / OPP 71 + metal oxide or ce- ramie 11 / OPP 71 + metallization 10 / PE.

Modes for Carrying out the Invention

As indicated above, one subject matter of the present invention is a recyclable container, in particular a tube comprising a container, preferably a container body and most preferred a container laminate that is at least 90 % PE or PP, in particular PE. Some presently preferred container laminates are shown in the Figures.

In some embodiments the 90 % polyolefins of one kind are only obtained for the container (laminate with sheathing and shoulder/head) or the container body (laminate with sheathing only).

Fig. 1 is an enlarged fragmentary sectional view of the container or tube body showing the seam section wherein overlapping edges 2 and 3 of the container laminate 1 are sealed and wherein the whole body, in particular also the seal are coated with a sheathing 4. The container laminate 1 is shown as three layer material with an inner polyolefin layer 6, an outer polyolefin layer 8 and a barrier layer 7 sandwiched between these two layers.

Fig. 2 shows a container laminate 1 with - from inside to outside - PE 6 / adhesive 9 / MDO-PE 71 + metallization 10 or metal oxide or ceramic layer 11 / adhesive 9 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 160 mm is composed as follows from inside PE (6) to outside PE (8):

70 mm LLDPE/HDPE - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 20 mm MDO-PE with metallization - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 70 mm LDPE).

Fig. 3 shows a laminate with - from inside to outside - PE 6 / adhesive / MDO-PE 71 + lacquer 12 + met- allization 10 or metal oxide or ceramic layer 11 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 160 mm is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based ad- hesive (approx. 1.5 g/m ² ) - 20 mm MDO-PE with PVOH based barrier lacquer (approx. 1 g/m ² ) and optional metallization 10 or metal oxide or ceramic layer 11 - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 70 mm LDPE.

Fig. 4 shows a laminate with - from inside to outside - PE 6 / adhesive 9 / MDO-PE-EVOH 72 (PE-layers 72a and EVOH layer 72b) + metallization 10 or metal oxide or ceramic layer 11 / adhesive 9 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 160 mm is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 20 mm MDO-PE-EVOH with optional metallization or metal oxide or ceramic layer - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 70 mm LDPE.

Fig. 5 shows a laminate with - from inside to outside - PE 6 / adhesive 9 / MDO-PE-EVOH 72 (PE-layers 72a and EVOH layer 72b) + barrier lacquer 12 + metallization 10 or metal oxide or ceramic layer 11 / adhesive 9 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 160 mm is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 20 mm MDO-PE-EVOH with bar- rier lacquer (approx. 1 g/m ² ) and with optional metallization 10 or metal oxide layer 11 - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 70 mm LDPE.

In an alternative embodiment of Figure 5 (not shown) the following sequence of the layers is present (from inside to outside): PE 6 / adhesive 9 / barrier lacquer 12 on MDO-PE-EVOH 72 (PE-layers 72a and EVOH layer 72b) + metallization 10 or metal oxide or ceramic layer 11 / adhesive 9 / PE 8.

Fig. 6 shows a laminate with - from inside to outside - PE 6 / adhesive 9 / OPP 71 + metal oxide or ceramic 11 / adhesive 9 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 160 mm is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 16-20 mm OPP with AlxOy or SiOx - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 70 mm LDPE.

Fig. 7 shows a laminate with - from inside to outside - PE 6 / adhesive 9 / OPP 71 + metallization 10 / adhesive 9 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 160 mm is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 16-20 mm OPP - metallization - SF polyurethane based adhesive (approx. 1.5 g/m ² ) 70 mm LDPE.

Fig. 8 shows a laminate with a barrier layer that is a barrier foil laminate. In detail, Fig. 8 shows - from inside to outside: PE 6 / adhesive 9 / metallization 10 (or metal oxide or ceramic 11) on OPP 71 / adhesive 9 / OPP 71 + metal oxide or ceramic 11 (or metallization 10) / adhesive 9 / PE 8. A presently preferred embodiment of the above material with a thickness of approx. 300 to 500 mm (comprising a LDPE sheathing) is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based adhe- sive (approx. 1.5 g/m ² ) - 16-20 mm OPP with metallization (or AlxOy or SiOx) - SF polyurethane based adhesive (approx. 1 mm) - 16-20 mm OPP with AlxOy or SiOx (or metallization) - SF adhesive (approx. 1.5 g/m ² ) - 70 mm LDPE.

Fig. 9 shows a laminate with - from inside to outside - PE 6 / adhesive 9 / OPP 71 + metal oxide or ceramic 11 / adhesive 9 / OPP 71 + metallization 10 / adhesive 9 / PE 8.

A presently preferred embodiment of the above material with a thickness of approx. 300 to 500 mm is composed as follows:

70 mm LLDPE/HDPE - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 16-20 mm OPP + AlxOy - SF polyurethane based adhesive (approx. 1.5 g/m ² ) - 16-20 mm OPP with metallization - SF polyurethane based adhesive (approx. 1 mm) - 70 mm LDPE.

In preferred embodiments, the inner PE-foil 6 is of a mixture of LLDPE/HDPE, preferably in a ratio of 70 % to 30 %, and the outer PE-foil is of LDPE.

In another embodiment both, the inner PE-foil 6 and the outer PE-foil 8 are of MDPE.

With regard to the barrier effect, a coextruded barrier foil is preferred, namely a highly oriented EVOH layer with small thickness (1-3 mm) within a MDO (mono-directionally oriented) PE foil.

The barrier effect of any of the polymeric barrier foils can be enhanced by applying at least on additional barrier layer selected from a barrier lacquer, a metallization like A1 and/or a metal oxide or ceramic thin film barrier like AlxOy or SiOx.

The adhesive layers can be the same or different but preferably are the same and much preferred are two-component polyurethane based and solvent-free or water based adhesives.

While there are shown and described presently preferred embodiments of the invention, it is to be dis- tinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.