Patent Application
20240300702
The present invention relates to a flexible tube container formed from blown film multi-layer polymeric material. Said tubes are designed to store and distribute liquid to pasty products. These flexible tubes include a head and a flexible skirt that is itself obtained from a “laminated” strip, including several layers of different plastics. The plane strip used within the context of this invention is cut out from a film which includes several layers of different plastics, which combine the various functions that a tube skirt must fulfill such as flexibility, dead-fold properties, act as a barrier to diffusion, be able to accept printing, etc.
It is known from the state of the art multi-layer flexible tube skirt, primarily comprising a polymeric intermediate layer with a barrier effect with regard to oxygen and to flavors, typically made from EVOH (polymeric ethylene-vinyl alcohol)), said layer being sensitive to moisture, and on each face of this intermediate layer, one or more polymeric layers containing polyolefin, all said layers being continuously bonded to each other. Such tube skirt can also comprise a layer comprising pigments in order to control the opacity of the skirt.
A typical drawback of plastic material is that it can become yellowish through time. This yellowing of the plastic can also affect the tube skirt. Such yellowing is problematic as it does not give a quality image to the product.
The yellowing of the plastic tube skirt can be influenced by light exposure, due notably to UV beam. The yellowing of the skirt is more significant for skirt with less opacity. Thus, increasing the opacity of the skirt will helps to mask a possible yellowing of the skirt. However, pigments may alter the mechanical properties of the polymeric layer they are mixed with. Thus, increasing the quantity of pigment in one specific layer may cause processability issues.
The yellowing of the plastic tube skirt can also be influenced by moisture. The moisture can come from the storage environment of the tube and from the product contained by the tube. Some polyolefin, such as polyethylene (PE), have relative moisture barrier effect. In particular, a layer made of PE may have different properties depending on the type of PE which is used. PE with low density are easy to process but are poor moisture barrier, whereas PE with higher density have better moisture barrier properties but are more difficult to process. Therefore, none of these are entirely satisfactory.
The present invention attempts to solve at least one of the above mentioned problems and propose a flexible tube container comprising tube head and a skirt formed from a multi-layer polymeric material produced as a blown film, the skirt comprising a longitudinal weld or join, the multi-layer polymeric material comprising a thickness of between 200 and 400 micrometers, said multi-layer polymeric material comprising two PE based surface layers, at least two non-metallic barrier layers, and a plurality of PE based inner layers between said surface layers, wherein the multi-layer polymeric material comprises pigments in several inner layers.
It has been discovered that, for the same overall quantity of pigment in the tube skirt, when the pigments are distributed among several layers instead of a single layer, the opacity is increased. Therefore, the flexible tube according to the invention allows to increase the opacity of the tube skirt while avoiding any processability issues. The risk of yellowing of the skirt is therefore reduced.
The invention can also comprise any of the following features taken individually or in any technically possible combination:
The invention will be better understood thanks to the following description which is only indicative and which is not intended to limit said invention, accompanied with the following figures:
In the context of the invention, the following definitions and abbreviations are used. As used herein, the terms “outer”, “inner”, “upper” and “lower”, and the like, used with respect to the various layers refer to the laminated material with the intended outer or upper surface uppermost and the intended inner or lower (product-contacting) surface lowermost. In addition, these terms and the terms “over”, “under” or “on” do not imply that the layers are necessarily directly in contact. For example, the upper layer being “formed on” the barrier layer does not preclude the presence of one or more other intervening layers located between the upper layer and the barrier layer. Furthermore, layers may be provided under the inner layer, i.e. between the inner layer and the product, or above the outer layer (like decorative layers).
The term “container” is used herein to refer to an item which may contain a product. Such products are usually liquids, gels or pastes. Preferred containers include tubes and pouches. The container may further comprise a lid or a cap and, if necessary, attachment means for the lid or cap (such as a tube head or shoulder) before it forms a useful commercial container. As a consequence, the laminated material of the invention can form a tube skirt, an insert of a tube head or a combination thereof.
The term “flexible laminate” as used herein describes a laminate or a container made thereof which can bend or be bent easily and which does not break (unless it is bent too much). Herein in connection with the containers the term flexible indicates that if the container is subjected to a force, for example, by being filled with a liquid, or by applying pressure with a finger or a hand, it will change its form without breaking. A flexible container can also be considered to be a “squeezable” container.
The term “tie layer” refers to a layer which is placed between two layers with the object of ensuring that the two layers are joined together.
The term “polymer” refers to a large molecule, or macromolecule, composed of many repeated subunits.
The term “polyolefin” refers to any of a class of polymers produced from a simple olefin as a monomer.
The term “PP” refers to polypropylene.
The term “PE” refers to polyethylene.
The term “LDPE” refers to low density polyethylene.
The term “LLDPE” refers to linear low density polyethylene.
The term “MDPE” refers to medium density polyethylene.
The term “HDPE” refers to high density polyethylene.
As illustrated in
The tube head 10 comprises a wall with a distribution opening and is attached or linked to the tube skirt 100. According to an embodiment, the head 10 can comprise a shoulder 11 and a neck 12. The neck advantageously comprises thread. The cap can be screwed on the neck in order to block the distribution opening.
According to another embodiment, the cap can be snapped on the neck, the neck comprising snap function such as an annular rib cooperating with flanges or tabs of the cap.
According to yet another embodiment represented at
According to an embodiment, the tube 1 can also comprise an insert located inside the tube 1 and attached to the internal surface of the head 10. In this case, the cap advantageously comprise a punch configured to pierce or cut the insert during the first use of the tube 1. More advantageously, the tube 1 according to this embodiment comprises a ring mounted on the head. Said ring allows to maintain the cap in a first position, called waiting position, in which the pinch is kept at distance from the insert.
As illustrated in
As represented in
Embodiments of the structures of the multi-layer polymeric material 200 according to the invention are illustrated at
The multi-layer polymeric material 200 comprises at least two non-metallic barrier layers 220.
The multi-layer polymeric material 200 comprises a plurality of PE based inner layers 210 between the surface layers 201. The inner layers can be made of several sub-layers 210a, preferentially two sub-layers, not necessary of the same thickness, but of the same material, i.e. consisting of a polymer or a mixture of several polymers in identical proportions, said polymer(s) being produced from monomers with the same chemical composition and substantially the same average molar mass. The sub-Layers 210a are particularly detectable during the manufacture of the multi-layer polymeric material 200.
The multi-layer polymeric material 200 forming the skirt 100 of the tube 1 according to the present invention comprises pigments in several inner layers 210 or sub-layers 210a. Consequently, as the pigments are distributed among several layers (or sub-layers) instead of a single layer, the opacity is increased. This technical effect is illustrated by the opacity comparison between different laminated materials presented in table 1 below.
59%
OTR corresponds to the Oxygen Transmission Rate. This parameter is measured with oxygen permeation testing analyzer such as MOCON, the measure being notably realized according to the standard test method ASTM F1927.
MVTR corresponds to the Moisture Vapor Transmission Rate. This parameter is also measured with MOCON analyzer, the measure being notably realized according to the standard test method ASTM F1249.
In column 6, the HDPE presents a density range higher than 0.96. The indicated weight % is calculated for the tube skirt.
The pigment used in these tests correspond to white Master Batch. The white Master Batch is a solid additive for plastic used for coloring plastics, it comprises 70% in mass of titanium dioxide (TiO2). The indicated weight % is calculated for the tube skirt.
The Opacity is measured with benchtop spectrophotometers, notably on X-Rite i7, according to an internal method.
Concerning the yellowing of the skirt, the more “+” indicated in the table, the more the skirt is yellow. This feature is a visual observation.
As it can be seen in this table 1, when the number of layers (or sub-layers) comprising pigment increases, the general opacity of the multi-layer polymeric material 200 increases. More particularly, a similar opacity can be obtained with less pigment when said pigment is distributed in several layers (or sub-layers). In particular, it was observed that good opacity results are obtained when a layer comprises several thin sub-layers, as in samples 5 and 6. Indeed, the overall quantity of pigment in sample 1 is much higher than the other samples. Sample 1 comprises pigment only in four layers. It is noted that, when the pigments are distributed in a higher number of layers (or sub-layers), it is possible to obtain a satisfactory opacity with significantly less pigments (see notably sample 6 with only 3.8% in weight of pigment).
As mentioned above, if the quantity of pigment is too important in a single layer, said layer may be difficult to process. As the overall quantity of pigment is split into the inner layers 210 (or sub-layers 210a), for one inner layer 210 as such, the quantity of pigment become sufficiently low to avoid processability issue. Consequently, each inner layer can be easily produced during manufacturing of multi-layer polymeric material 200 by blown film process.
The total thickness of the multi-layer polymeric material 200 does not influence its quality. A thinner multi-layer polymeric material 200, for example of a total thickness of 200 or 220 micrometers, has similar results as a multi-layer polymeric material 200 with a total thickness of 250 μm.
Therefore, the flexible tube 2 according to the invention allows to increase the opacity of the tube skirt 100 while avoiding any processability issues. This technical feature helps to treat the symptom of yellowing of the skirt. The visible yellowing of the skirt is therefore reduced and the quality image of the product is improved.
As an overall view, the multi-layer polymeric material 200 contains a sufficiently high quantity of pigment to obtain a satisfactory opacity.
In a preferred embodiment, the quantity of pigment is evenly distributed into each inner layer.
Preferably, the multi-layer polymeric material 200 comprising a thickness of between 200 and 400 micrometers. Advantageously, the multi-layer polymeric material comprising a thickness of between 200 and 370 micrometers, preferably between 200 and 350 micrometers, more preferably between 200 and 330 micrometers and more preferably between 200 and 250 micrometers.
Advantageously the multi-layer polymeric material 200 has a symmetrical structure with respect to its median plane. More particularly, the multi-layer polymeric material 200 has symmetrical layers with substantially the same thickness and substantially made up of the same plastic, i.e. consisting of a polymer or a mixture of several polymers in identical proportions, said polymer(s) being produced from monomers with the same chemical composition and substantially the same average molar mass. Here, it is attempted to limit the heterogeneous behavior of the various layers by aiming at as perfect as possible a symmetry in relation to the median plane of the multi-layer polymeric material 200, not only geometrical but also concerning the material used, it not being deemed sufficient to have the same chemical composition of the basic monomer(s).
Preferably, the pigments are distributed in 2n inner layers, n being an integer.
Advantageously, the multi-layer polymeric material 200 comprises from 3% to 7% in mass of pigment. This proportion of pigments allows to obtain a sufficient opacity while still keeping satisfactory mechanical properties.
As illustrated at
Advantageously, the multi-layer polymeric material 200 comprises a central layer 211. When there is a single central layer 211, the median plane of the multi-layer polymeric material 200 is located at the center of said central layer 211.
Alternatively, the multi-layer polymeric material 200 can comprise two central layers 211.
Alternatively, the multi-layer polymeric material 200 can comprise one central layers 211 made of two sub-layers 211a. The sub-layers are not necessary of the same thickness, but they are of the same material, i.e. consisting of a polymer or a mixture of several polymers in identical proportions, said polymer(s) being produced from monomers with the same chemical composition and substantially the same average molar mass.
In this configurations, the median plane of the multi-layer polymeric material 200 is located between said central layers 211. The sub-Layers 211a are particularly detectable during the manufacture of the multi-layer polymeric material 200.
Advantageously, each inner layer 210 of the multi-layer polymeric material 200 forming the skirt 100 of the tube 1 according to the invention comprises mixture of different type of PE, more particularly, PE with different density. Indeed, PE with higher density allows a better moisture barrier effect but are more difficult to process than the PE with lower density. In the same way, PE with lower density are weak moisture barrier but are easier to process. Therefore, the mixture of PE, i.e. the ratio of different type of PE, is advantageously selected in order to balance the moisture barrier effect and the processability. A better moisture barrier effect will help to reduce the yellowing of the skirt. This technical effect is illustrated by the moisture barrier comparison between different laminated materials presented in table 1 above. As can be seen when comparing the Moisture Vapor Transmission Rate (MVTR) of the different samples, samples 4, 5 and 6 have a less important MVTR than sample 1, 2 and 3. The multi-layer polymeric material 200 according to samples 4, 5 and 6 comprises a higher percentage of High Density PE than the multi-layer polymeric material 200 according to samples 1, 2 and 3. The increased proportion of High Density PE helps to improve the moisture barrier effect and, consequently, helps to reduce the yellowing of the skirt 100. This feature helps to treat the cause of the yellowing of the skirt.
According to an embodiment illustrated in
According to an embodiment illustrated in
The mixture presented in these embodiments allows for a better touch and less stiffer skirt. Said mixtures also allow for less cracking noise when the tube 1 is squeezed.
Advantageously, each inner layer 210 comprise HDPE.
Preferably, the at least two non-metallic barrier layers 220 are made of EVOH. Such barrier layer 220 has good barrier effect with regard to oxygen and to flavors.
More preferably, the multi-layer polymeric material 200 comprises tie layers 221 on both side of each barrier layer 220. These tie layers 221 improve the bonding between the barrier layer and the adjacent inner layers 210.
More preferably, the multi-layer polymeric material comprises 2n barrier layers 220.
Advantageously, one specific type of PE represents at least 60% in mass of the multi-layer polymeric material 200. This ratio allows to pass into recyclability channel of said type of PE.
The following structures are exemplary embodiments of multi-layer polymeric material 200 according to the present invention. The invention is not restricted to the specific multi-layer polymeric material of the exemplary embodiments but encompasses other multi-layer polymeric material structures falling within the scope of the appended claims.
The different layers of these exemplary embodiments of laminated material are described starting from the external surface layer, i.e. the intended outer surface uppermost, to the internal surface layer, i.e. the intended inner (product-contacting) surface lowermost.
This example corresponds to the embodiment schematically represented at
This example corresponds to the embodiment schematically represented at
This example corresponds to the embodiment schematically represented at
This example corresponds to the embodiment schematically represented at
This example corresponds to the embodiment schematically represented at
This example corresponds to the embodiment schematically represented at
The following structures are comparative exemplary embodiments of multi-layer polymeric material.
The different layers of these comparative exemplary embodiments of laminated material are described starting from the external surface layer, i.e. the intended outer surface uppermost, to the internal surface layer, i.e. the intended inner (product-contacting) surface lowermost.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21188602.3 | Jul 2021 | EP | regional |
This application is the National Stage of International Application No. PCT/EP2022/071460, filed Jul. 29, 2023, which claims priority to European Application No. 21188602.3, filed Jul. 29, 2021, and the contents of which are incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/071460 | 7/29/2022 | WO |
