RECYCLABLE, SEALABLE CONTAINER

Abstract

A recyclable, sealable packaging that has one or several polyamides, in a proportion greater than or equal to 90% by weight with respect to the total, and the sealing layer consists of one or several polyamides that are sealable at less than 200° C. is disclosed. The invention affords the main advantages of being recyclable after its use and having a sufficiently low melting temperature for it to seal with itself and with other polyamides.

Claims

1. A recyclable, sealable packaging with identifiable composition, selectively separable from other plastic wastes and reusable characterised in that it comprises: one or several polyamides in a proportion greater than or equal to 90% by weight with respect to the total, and other polymers, different to the said polyamides, inks and/or additives, in a proportion less than or equal to 10% by weight with respect to the total, the sealing layer consisting of a polyamide that seals at less than 200° C.

2. The recyclable, sealable packaging according to claim 1, wherein the polyamide or polyamides are manufactured from monomers chosen from the group formed by adipic acid, isophthalic acid, terephthalic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 1,5-pentanediamine, xylylenediamine, caprolactam, laurolactam, and omega-aminoundecanoic acid.

3. eThe recyclable, sealable packaging according to claim 1, wherein the other polymers, different to the said polyamide, are chosen from the group formed by ethylene-vinyl-alcohol, (EVOH), polyethylene (LDPE, LLDPE, mLLDPE, MDPE, HDPE), modified polyethylene, polypropylene (PP), modified polypropylene, polyethylene terephthalate (PET, PETG, CPE), polyvinyl chloride (PVC) , polystyrene (PS), ionomers, ethylene vinyl acetate (EVA), ethylene butyl acetate (EBA), cyclic olefin copolymer (COC), AlOx, SiOx or a combination of them.

4. The recyclable, sealable packaging, according to claim 1, wherein the polyamide comprises meta-xylylenediamine in a proportion greater than or equal to 5% by weight with respect to the total, isophthalic acid also known as IPA and/or terephthalic acid also known as PTA, in such a way that the sum of the contents of both is greater than or equal to 3%, by weight with respect to the total, and caprolactam in a proportion less than or equal to 89% by weight with respect to the total.

5. The recyclable, sealable packaging, according to claim 4, wherein the meta-xylylenediamine is present in a proportion of between 5% and 30% by weight with respect to the total.

6. The recyclable, sealable packaging, according to claim 4, wherein the isophthalic acid and/or terephthalic acid are present in a proportion of between 3% and 18% by weight with respect to the total.

7. The recyclable, sealable packaging, according to claim 4, wherein the caprolactam is present in a proportion of between 34% and 89% by weight with respect to the total.

8. The recyclable, sealable packaging, according to claim 4, wherein it results in a composition with an oxygen permeability of less than 15 cc/m.sup.2/day, measured at 23° C. and 50% humidity, for a thickness of 50 microns.

9. The recyclable, sealable packaging, according to claim 1, wherein the polyamide comprises hexamethylenediamine in a proportion greater than or equal to 5% by weight with respect to the total, dodecanedioic acid in a proportion greater than or equal to 10% by weight with respect to the total, and caprolactam in a proportion less than or equal to 85% by weight with respect to the total.

10. The recyclable, sealable packaging, according to claim 9, wherein the hexamethylenediamine is present in a proportion of between 5% and 30% by weight with respect to the total.

11. The recyclable, sealable packaging, according claim 9, wherein the dodecanedioic acid is present in a proportion of between 10% and 60% by weight with respect to the total.

12. The recyclable, sealable packaging, according claim 9, wherein the caprolactam is present in a proportion of between 10% and 85% by weight with respect to the total.

13. The recyclable, sealable packaging, according claim 9, wherein it results in a composition with an oxygen permeability greater than 15 cc/m.sup.2/day, measured at 23° C. and 50% humidity, for a thickness of 50 microns.

14. The recyclable, sealable packaging, according to claim 9, wherein it results in a composition with a CO.sub.2 permeability greater than 105 cc/m.sup.2/day, measured at 23° C. and 0% humidity, for a thickness of 50 microns.

Description

PREFERRED EMBODIMENT OF THE INVENTION

[0036] The constitution and features of the invention may be better understood from the following description, in which we specify that the recyclable, sealable packaging comprises: [0037] one or several polyamides in a proportion greater than or equal to 90% by weight with respect to the total, preferably 95%, and more preferably 100%, and [0038] other polymers, different to the said polyamides, inks and/or additives, in a proportion less than or equal to 10% by weight with respect to the total,
the sealing layer consisting of one or several polyamides that seal at less than 200° C. and resulting in an identifiable composition, selectively separable from other plastic waste and thus reusable. Identification and selective separation from other wastes is carried out by means of suitable technologies, such as, for example, infrared technology.

[0039] To achieve these properties of being identifiable, selectively separable and hence reusable, it is important that the percentage of polyamide is as high as possible, ideally 100%, although, due to technical requirements of the packaging, this percentage can be reduced, and up to 10% of other materials can be incorporated without this significantly lessening the said properties.

[0040] This composition is applicable both to single-layer packagings, in which case the sealing layer is considered to be the only layer that exists, and to multi-layer packagings, in which case the sealing layer is considered to be one of the outer layers.

[0041] This composition achieves a sufficiently low melting temperature for it to seal with itself and with other polyamides. In particular, for a thickness of 50 microns, sealing is obtained at a temperature of less than 200° C., preferably less than 160° C. and more preferably less than 140° C. The seal strength thus obtained is greater than 18 MPa.

[0042] The sealable polyamide or polyamides are manufactured, preferably but not exclusively, from monomers such as adipic acid, isophthalic acid, terephthalic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 1,5-pentanediamine, xylylenediamine, caprolactam, laurolactam, omega-aminoundecanoic acid, etc.

[0043] The other polymers, different to the said polyamide are chosen from the group formed by ethylene-vinyl-alcohol, (EVOH), polyethylene (LDPE, LLDPE, mLLDPE, MDPE, HDPE), modified polyethylene, polypropylene (PP), modified polypropylene, polyethylene terephthalate (PET, PETG, CPE), polyvinyl chloride (PVC) , polystyrene (PS), ionomers, ethylene vinyl acetate (EVA), ethylene butyl acetate (EBA), cyclic olefin copolymer (COC), AlOx, SiOx or a combination of them.

[0044] In a preferred embodiment of the recyclable, sealable packaging, the polyamide comprises [0045] meta-xylylenediamine in a proportion greater than or equal to 5%, preferably between 5% and 30% by weight with respect to the total, [0046] isophthalic acid also known as IPA and/or terephthalic acid also known as PTA, in such a way that the sum of the contents of both is greater than or equal to 3%, preferably in a proportion of between 3% and 18% by weight with respect to the total, and [0047] caprolactam in a proportion less than or equal to 89%, preferably in a proportion of between 34% and 89% by weight with respect to the total.

[0048] This composition achieves an oxygen permeability of less than 15 cc/m.sup.2/day, measured at 3° C. and 50% humidity, preferably less than 11 cc/m2/day, and more preferably less than 8 cc/m2/day, for a thickness of 50 microns, which is therefore lower than that of standard PA6 or Nylon 6 polyamide that presents a permeability of between 15 and 20 cc/m.sup.2/day in the same conditions, thus achieving a better oxygen barrier effect.

[0049] In an alternative embodiment of the recyclable, sealable packaging, the polyamide comprises [0050] hexamethylenediamine in a proportion greater than or equal to 5%, preferably in a proportion of between 5% and 30% by weight with respect to the total, [0051] dodecanedioic acid in a proportion greater than or equal to 10%, preferably in a proportion of between 10% and 60% by weight with respect to the total, and [0052] caprolactam in a proportion less than or equal to 85%, preferably in a proportion of between 10% and 85% by weight with respect to the total,

[0053] This composition achieves an oxygen permeability greater than 20 cc/m.sup.2/day, measured at 23° C. and 50% humidity, preferably greater than 30 cc/m.sup.2/day, and more preferably greater than 50 cc/m.sup.2/day, for a thickness of 50 microns, which is therefore higher than that of standard PA6 or Nylon 6 polyamide that presents a permeability of between 15 and 20 cc/m.sup.2/day in the same conditions, thus obtaining better oxygen permeability. Likewise, it achieves a CO.sub.2 permeability greater than 105 cc/m.sup.2/day, preferably greater than 200 cc/m.sup.2.day, measured at 23° C. and 0% humidity, for a film thickness of 50 microns, which is therefore higher than that of standard PA6 o Nylon 6 polyamide that presents a permeability of between 95 and 105 cc/m.sup.2/day in the same conditions, thus obtaining better CO.sub.2 permeability.

[0054] This recyclable, sealable packaging described has a characteristic use in food applications, in particular, in the production of vacuum packaging, skin packaging, shrink packaging, bags, and also trays, lids and other types of containers. Its use as packaging for non-food applications is also characteristic and possible.

[0055] To achieve the described result various experimental trials have been conducted, among which the following are highlighted:

[0056] Gas Permeability

[0057] Based on the composition indicated in the preferred embodiment, measurements have been made in films with a thickness of 50 microns, verifying that their gas permeability, both to oxygen and carbon dioxide CO.sub.2, is lower in all cases than the standard PA6 polyamide, thus exhibiting a better gas barrier effect.

TABLE-US-00001 TABLE 1 Oxygen permeability CO.sub.2 permeability (cc/m.sup.2/day) (cc/m.sup.2/day) 23° C. 23° C. 23° C. 50% relative 85% relative 0% relative humidity humidity humidity PA6 (Nylon 6) 15-20 35-50  95-105 polyamide Recyclable, sealable  5-11 20-30 80-90 packaging

[0058] With the composition indicated in the alternative embodiment, measurements have also been made in films with a thickness of 50 microns, verifying that their gas permeability, both to oxygen and carbon dioxide CO.sub.2, is higher in all cases than the standard PA6 polyamide, thus exhibiting a better gas permeability effect.

TABLE-US-00002 TABLE 2 Oxygen permeability CO.sub.2 permeability (cc/m.sup.2/day) (cc/m.sup.2/day) 23° C. 23° C. 23° C. 50% relative 85% relative 0% relative humidity humidity humidity PA6 (Nylon 6) 15-20 35-50  95-105 polyamide Recyclable, sealable 50-90 100-130 265-275 packaging

[0059] Melting Temperature

[0060] Based on the composition indicated in the preferred embodiment, in a Differential Scanning calorimetry (DSC) test in which a sample of pellets of the compound is heated at a speed of 10° C./min to 250° C., at least one endothermic peak should appear at a temperature lower than or equal to 205° C., preferably lower than or equal to 185° C. An endothermic peak=Peak value: 183° C., Endset: 189° C. is obtained

[0061] With the composition indicated in the alternative embodiment and in the same previous conditions and requirements, an endothermic peak=Peak value: 160° C., Endset: 172° C. is obtained.

[0062] A person skilled in the art will easily comprehend that the characteristics of different embodiments can be combined with the characteristics of other possible embodiments, provided that the combination is technically possible.

[0063] All of the information referring to examples or embodiments form part of the description of the invention.