METHOD FOR MANUFACTURING A CLOSURE FOR A PRODUCT-RETAINING CONTAINER

Abstract

A method for manufacturing a closure constructed to be inserted and securely retained in a neck of a product-retaining container includes intimately combining a plurality of coated particles (each comprising a cork material core and a first plastic material) with a second plastic material, and other optional constituents; heating the composition to form a melt; extruding or molding a closure precursor from the melt; and optionally cutting and/or finishing the closure precursor. A composition for use in manufacturing a closure includes a plurality of coated particles (each comprising a cork material core and a first plastic material) with a second plastic material, and one or more blowing agents. Methods for producing particulate material, cork composite material, and additional method for producing closures are also provided.

Claims

1. A method for manufacturing a closure for a product-retaining container constructed for being inserted and securely retained in a portal-forming neck of said product-retaining container, said method comprising at least the following method steps: i. intimately combining the following components, to form a composition: (a) 51 to 80 wt. % (dry weight) or 51 to 85 wt. % (dry weight) of a plurality of coated particles, said coated particles each comprising (1) a core comprising cork material and (2) at least one outer shell comprising a first plastic material, said first plastic material comprising one or more thermoplastic polymers; (b) 12 to 49 wt. % of a second plastic material comprising one or more thermoplastic polymers; (c) optionally 0 to 10 wt. % of one or more blowing agents; (d) optionally, 0 to 15 wt. % of one or more lubricants; (e) optionally, 0 to 2 wt. % of one or more pigments; and (f) optionally, 0 to 10 wt. % of one or more additives and/or fillers; ii. heating the composition obtained in step i. to form a melt; iii. forming, by means of extrusion or molding, a closure precursor from the melt obtained in step ii; and iv. optionally cutting and/or finishing the closure precursor to form the closure.

2. A method for manufacturing a closure for a product-retaining container constructed for being inserted and securely retained in a portal-forming neck of said product-retaining container, said method comprising at least the following method steps: i. intimately combining the following components, to form a composition: (a) 52 to 100 wt. % (dry weight) of a plurality of coated particles, said coated particles each comprising (1) a core comprising cork material and (2) at least one outer shell comprising a first plastic material, said first plastic material comprising one or more thermoplastic polymers; (b) 0 to 48 wt. % of a second plastic material comprising one or more thermoplastic polymers; (c) optionally 0 to 10 wt. % of one or more blowing agents; (d) optionally, 0 to 15 wt. % of one or more lubricants; (e) optionally, 0 to 2 wt. % of one or more pigments; and (f) optionally, 0 to 10 wt. % of one or more additives and/or fillers; ii. heating the composition obtained in step i. to form a melt; iii. forming, by means of extrusion or molding, a closure precursor from the melt obtained in step ii; and iv. optionally cutting and/or finishing the closure precursor to form the closure.

3. The method of claim 2, wherein the closure or closure precursor is substantially free of thermoset polymers (including polyurethane) and/or substantially free of adhesives (including reactive and non-reactive adhesives).

4. The method of claim 2, wherein the closure or closure precursor has a content of releasable trichloroanisole measured according to the test method defined herein of less than 2 ng/L, preferably less than 1 ng/L, preferably less than 0.5 ng/L, preferably less than 0.3 ng/L.

5. The method of claim 2, wherein steps i., ii., and iii. are carried out sequentially or simultaneously and/or wherein at least one of steps i., ii., and iii. is carried out in an extruder.

6. The method of claim 2, wherein each one of steps i., ii., and iii. is carried out in an extruder.

7. The method of claim 2, wherein the temperature in any of steps i., ii., and iii. does not exceed 200? C.

8. The method of claim 2, wherein the pressure in any of steps i., ii. and iii. does not exceed 30 bar.

9. The method of claim 2, wherein during the heating step ii., at least one of the first plastic material or the second plastic material is foamed.

10. The method of claim 2, wherein the components (a), (b), and (c) are present in the following weight percent amounts, based on the total weight of the composition: (a) 55 to 65 wt. % of the plurality of coated particles (dry weight); (b) 24.9 to 34.9 wt. % of the second plastic material; (c) 0.1 to 4 wt. % of a blowing agent selected from expandable microspheres.

11. The method of claim 2, wherein the components (a), (b), and (c) are comprised in the following weight percent amounts, based on the total weight of the composition: (a) 65 to 85 wt. % of the plurality of coated particles (dry weight); (b) 14.9 to 29.9 wt. % of the second plastic material; (c) 0.1 to 4 wt. % of a blowing agent selected from expandable microspheres.

12. The method of claim 2, wherein coated particles of said plurality of coated particles have a substantially isotropic shape.

13. The method of claim 2, wherein, for each coated particle, the core is a cork particle having a particle size distribution D.sub.50 measured by means of mechanical sieving according to ISO ICS 19.120 and in particular ISO 2591-1:1988, in the range of from 0.25 millimetres to 5 millimetres.

14. The method of claim 2, wherein, for each coated particle, the core is a cork particle, and the cork particles comprise a mixture of at least: from 5 wt. % to 100 wt. %, based on the total weight of the cork particles of smaller cork particles having a particle size distribution D.sub.50 measured by means of mechanical sieving according to ISO ICS 19.120 and in particular ISO 2591-1:1988, in the range of from 0.1 millimetres to less than 1.0 millimetre; and from 0 wt. % to 95 wt. %, based on the total weight of the cork particles of larger cork particles having a particle size distribution D.sub.50 measured by means of mechanical sieving according to ISO ICS 19.120 and in particular ISO 2591-1:1988, in the range of from 1.0 millimetre to 3.0 millimetres; or wherein the cork particles comprising cork comprise a mixture of at least: from 5 wt. % to 100 wt. %, based on the total weight of the cork particles of larger cork particles having a particle size distribution D.sub.50 measured by means of mechanical sieving according to ISO ICS 19.120 and in particular ISO 2591-1:1988, in the range of from 1.0 millimetre to 3.0 millimetres; and from 0 wt. % to 95 wt. %, based on the total weight of the cork particles of smaller cork particles having a particle size distribution D.sub.50 measured by means of mechanical sieving according to ISO ICS 19.120 and in particular ISO 2591-1:1988, in the range of from 0.1 millimetres to less than 1.0 millimetre.

15. The method of claim 2, wherein, for each coated particle, the core is a cork particle having a water content of less than 3 wt. %, in particular less than 2 wt. %, less than 1.5 wt. %., or less than 1 wt. %.

16. The method of claim 2, wherein, for each coated particle, the core is a cork particle and wherein said cork particles have a content of releasable trichloroanisole measured according to the test method defined herein of less than 6 ng/L.

17. The method of claim 2, wherein, for each coated particle, the core is a cork particle and wherein the density of said cork particles in the closure precursor or in the closure is in the range of 50 to 100 g/L.

18. The method of claim 2, wherein, for each coated particle, the core is substantially encapsulated by said at least one outer shell comprising said first plastic material.

19. The method of claim 2, wherein, for each coated particle, the at least one outer shell of said coated particles has a thickness of 5 to 100 microns.

20. The method of claim 2, wherein said second plastic material comprising one or more thermoplastic polymers has an average particle size distribution D50 measured by means of mechanical sieving according to ISO ICS 19.120 and in particular ISO 2591-1:1988, of less than 1000 microns.

21. The method of claim 2, wherein said second plastic material comprising one or more thermoplastic polymers is milled.

22. The method of claim 2, wherein said second plastic material comprising one or more thermoplastic polymers is provided in the form of a polymer dispersion, a polymer emulsion and/or polymer gum.

23. The method according to claim 2, wherein said second plastic material is provided in the form of a melt.

24. The method of claim 2, wherein at least one of said first plastic material or said second plastic material is thermoplastically processable.

25. The method of claim 2, wherein at least one of said first plastic material or said second plastic material comprises one or more polymers that are biodegradable according to ASTM D6400.

26. The method of claim 2, wherein at least 90 wt. % of said first plastic material and/or said second plastic material is biodegradable according to ASTM D6400.

27. The method of claim 2, wherein from 1% by weight to 49% by weight of the closure, based on the entire weight of the closure, is biodegradable according to ASTM D6400.

28. The method of claim 2, wherein said first and/or second plastic material comprises one or more thermoplastic polymers independently selected from the group consisting of: polyethylenes; metallocene catalyst polyethylenes; polybutanes; polybutylenes; thermoplastic polyurethanes; silicones; vinyl-based resins; thermoplastic elastomers; polyesters; ethylenic acrylic copolymers; ethylene-vinyl-acetate copolymers; ethylene-methyl-acrylate copolymers; thermoplastic polyolefins; thermoplastic vulcanizates; flexible polyolefins; fluorelastomers; fluoropolymers; polytetrafluoroethylenes; ethylene-butyl-acrylate copolymers; ethylene-propylene-rubber; styrene butadiene rubber; styrene butadiene block copolymers; ethylene-ethyl-acrylic copolymers; ionomers; polypropylenes; copolymers of polypropylene and ethylenically unsaturated comonomers copolymerizable therewith; olefin copolymers; olefin block copolymers; cyclic olefin copolymers; styrene ethylene butadiene styrene block copolymers; styrene ethylene butylene styrene block copolymers; styrene ethylene butylene block copolymers; styrene butadiene styrene block copolymers; styrene butadiene block copolymers; styrene isoprene styrene block copolymers; styrene isobutylene block copolymers; styrene isoprene block copolymers; styrene ethylene propylene styrene block copolymers; styrene ethylene propylene block copolymers; polyvinylalcohol; polyvinylbutyral; polyhydroxyalkanoates; copolymers of hydroxyalkanoates and monomers of biodegradable polymers; polylactic acid; copolymers of lactic acid and monomers of biodegradable polymers; aliphatic copolyesters; polycaprolactone; polyglycolide; poly(3-hydroxybutyrate); poly(3-hydroxybutyrate-co-3-hydroxyvalerate); poly(3-hydroxybutyrate-co-3-hydroxyhexanoate); poly(butylenesuccinate); aliphatic-aromatic copolyesters, in particular aliphatic-aromatic copolyesters comprising units derived from renewable resources and/or units derived from fossil resources, in particular one or more aliphatic-aromatic copolyesters selected from poly(butylenesuccinate-co-adipate); poly(trimethyleneterephthalate); poly(butylenadipate-co-terephthalate); poly(butylenesuccinate-co-terephthalate); poly(butylenesebacate-co-terephthalate); polymers derived from lactic acid, copolymers of lactic acid and monomers of biodegradable polymers, in particular selected from polylactic acid, lactic acid caprolactone lactic acid copolymers; lactic acid ethylene oxide lactic acid copolymers; polymers formed from monomer units selected from vinylidene chloride, acrylonitrile and methyl methacrylate; copolymers formed from two or more monomer units selected from vinylidene chloride, acrylonitrile and methyl methacrylate; PEF, PTF, bio-based polyesters, and combinations of any two or more thereof.

29. The method of claim 2, wherein said first and/or second plastic material comprises one or more thermoplastic polymers independently selected from the group consisting of aliphatic (co)polyesters, aliphatic aromatic copolyesters, polylactic acid, EVA, olefinic polymers such as metallocene polyethylene, and styrenic block copolymers.

30. The method of claim 2, wherein said first and/or second plastic material comprises one or more thermoplastic polymers having a melt flow index (MFI) as determined by ISO 1133-1 of greater 5, in particular greater 10 or greater 12.

31. The method of claim 2, wherein said first and second plastic materials are identical.

32. The method of claim 2, wherein said first and/or second plastic material is unfoamed and/or foamed plastic material.

33. The method of claim 2, wherein the composition in step i. comprises 0.05 to 10 wt. % of the one or more blowing agents.

34. The method of claim 33, wherein the one or more blowing agents are selected from the group consisting of expandable microspheres, chemical blowing agents, physical blowing agents, and combinations of two or more thereof.

35. The method of claim 2, wherein said closure or closure precursor comprises a plurality of cells.

36. The method of claim 35, wherein the plurality of cells comprises a plurality of substantially closed cells.

37. The method of claim 35, wherein each cell of the plurality of cells has an average cell size in a range of from about 0.025 mm to about 0.5 mm.

38. The method of claim 35, wherein at least one of a size and a distribution of cells of the plurality of cells in the closure is substantially uniform throughout at least one of a length or a diameter of the closure.

39. The method of claim 2, wherein the closure or the closure precursor has an overall density in the range of from 100 kg/m.sup.3 to 500 kg/m.sup.3.

40. The method of claim 2, wherein the first plastic material and/or the second plastic material in the closure or closure precursor has a foam density in the range of from 25 kg/m.sup.3 to 800 kg/m.sup.3.

41. The method of claim 2, wherein a distribution of the plurality of coated particles in the closure or the closure precursor is substantially uniform throughout at least one of a length or a diameter of the closure.

42. The method of claim 2, wherein coated particles of the plurality of coated particles are distributed homogeneously throughout the closure.

43. The method of claim 2, wherein the closure or the closure precursor does not comprise a binder; and/or wherein the closure does not comprise a crosslinking agent; and/or wherein the closure does not comprise a binder and does not comprise a crosslinking agent; and/or wherein the first plastic material and/or the second plastic material is not crosslinked by means of a crosslinking agent.

44. The method of claim 2, wherein the closure precursor in step iii. is formed by means of monoextrusion or co-extrusion.

45. The method of claim 2, wherein the closure precursor and/or the closure is further subjected to one or more surface treatments such as sanding, chamfering, bleaching, and/or coating.

46. A composition for use in manufacturing a closure for a product-retaining container, comprising as components: (a) 51 to 80 wt. % (dry weight) or 51 to 85 wt. % (dry weight) of a plurality of coated particles, said coated particles each comprising (1) a core comprising cork material and (2) at least one outer shell comprising a first plastic material, said first plastic material comprising one or more thermoplastic polymers; (b) 12 to 49 wt. % of a second plastic material comprising one or more thermoplastic polymers; (c) 0 to 10 wt. % of one or more blowing agents; (d) optionally, 0 to 15 wt. % of one or more lubricants; (e) optionally, 0 to 2 wt. % of one or more pigments; and (f) optionally, 0 to 10 wt. % of one or more additives and/or fillers.

47. A composition for use in manufacturing a closure for a product-retaining container, comprising as components: (a) 52 to 100 wt. % (dry weight) of a plurality of coated particles, said coated particles each comprising (1) a core comprising cork material and (2) at least one outer shell comprising a first plastic material, said first plastic material comprising one or more thermoplastic polymers; (b) 0 to 48 wt. % of a second plastic material comprising one or more thermoplastic polymers; (c) 0 to 10 wt. % of one or more blowing agents; (d) optionally, 0 to 15 wt. % of one or more lubricants; (e) optionally, 0 to 2 wt. % of one or more pigments; and (f) optionally, 0 to 10 wt. % of one or more additives and/or fillers.

48. A closure produced by the method of claim 1.

49. The closure of claim 48, wherein the closure has an oxygen ingress rate measured according to ASTM F1307 of less than about 5 mg oxygen per container in the first 100 days after closing the product-retaining container.

50. The closure of claim 48, wherein the closure has an oxygen ingress rate measured according to ASTM F1307 selected from the group consisting of less than about 1 mg oxygen, less than about 0.8 mg oxygen, less than about 0.5 mg oxygen, less than about 0.25 mg oxygen, less than about 0.2 mg oxygen and less than about 0.1 mg oxygen, per product-retaining container in the first 100 days after closing the product-retaining container.

51. The closure of claim 48, wherein the closure has an oxygen transfer rate measured according to ASTM F1307 in 100% oxygen of less than 0.05 cc/day.

52. The closure of claim 48, wherein the closure has a moisture rate as determined by ISO 9727-3 of less than 3%.

53. A closure for a product-retaining container constructed for being inserted and securely retained in a portal-forming neck of said product-retaining container, wherein the closure comprises: (a) a foamed plastic material comprising one or more thermoplastic polymers; and (b) a plurality of particles comprising cork; wherein the closure has a moisture content as determined by ISO 9727-3 of less than 3%.

54. The closure according to claim 53, wherein a distribution of the plurality of particles in the closure is substantially uniform throughout at least one of a length and a diameter of the closure.

55. The closure according to claim 48, having a surface roughness R.sub.a measured by contact profilometry in the range from 5 ?m to 18 ?m.

56. (canceled)

57. (canceled)

58. A closure system comprising the product-retaining container and the closure of claim 48.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0393] For a fuller understanding of the nature and objects of the present disclosure herein described, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

[0394] FIG. 1 is a perspective view of a closure according to an aspect of the present disclosure, comprising a peripheral layer;

[0395] FIG. 2 is a cross sectional-side elevation of a closure according to an aspect of the present disclosure, comprising a peripheral layer;

[0396] FIG. 3 is a perspective view of a closure according to an aspect of the present disclosure, not comprising a peripheral layer;

DETAILED DESCRIPTION

[0397] By referring to the FIGURES, along with the following detailed disclosure, the construction and production method for the closures of the present disclosure can best be understood. In these Figures, as well as in the detailed disclosure herein, the closure of the present disclosure, is depicted and discussed as a bottle closure for wine products. However, as detailed herein, the present disclosure is applicable as a closure for use in sealing and retaining any desired product in any desired closure system. However, due to the stringent and difficult demands placed upon closures for wine products, the detailed disclosure herein focuses upon the applicability of the bottle closures of the present disclosure as a closure for wine bottles. However, it is to be understood that this detailed discussion is provided merely for exemplary purposes and is not intended to limit the present disclosure to this particular application and embodiment.

[0398] In FIGS. 1 and 2, the exemplary construction of a closure 20 is depicted comprising a generally cylindrical shape formed by core member 22 and peripheral layer 24 which peripherally surrounds and is intimately bonded to core member 22. In this aspect, core member 22 comprises a substantially cylindrically shaped surface 26, terminating with substantially flat end surfaces 27 and 28. Whenever applicable, the following detailed description of a closure having a layered structure, i.e. a core member and a peripheral layer, shall also apply to closures without a peripheral layer and also to multilayer closures having more than one peripheral layer.

[0399] In an exemplary aspect, peripheral layer 24 is intimately bonded directly to core member 22, peripherally surrounding and enveloping surface 26 of core member 22. Peripheral layer 24 incorporates exposed surface 29, which comprises a substantially cylindrical shape and forms the outer surface of bottle closure 20, along with surfaces 27 and 28 of the substantially flat terminating ends.

[0400] In order to assist in assuring entry of bottle closure 20 into the portal of the bottle into which closure 20 is inserted, terminating edge 31 may be beveled or chamfered. Similarly, terminating edge 32 may comprise a similar bevel or chamfer. Although any desired bevel or chamfered configuration can be employed, such as a radius, curve, or flat surface, it has been found that by merely cutting ends 31 and 32 with an angle of about 45? or about 60? the desired reduced diameter area is provided for achieving the desired effect. The chamfer angle and the chamfer length, i.e. the length of the chamfered surface as measured between surface 26, or surface 29 if a peripheral layer is comprised, are exemplarily within the ranges described herein for still wine closures or champagne closures.

[0401] By incorporating chamfered or beveled ends 31 and 32 on bottle closure 20, automatic self-centering is attained. As a result, when bottle closure 20 is compressed and ejected from the compression jaws into the open bottle for forming the closure thereof, bottle closure 20 is automatically guided into the bottle opening, even if the clamping jaws are slightly misaligned with the portal of the bottle. By employing this configuration, unwanted difficulties in inserting bottle closure 20 into any desired bottle are obviated. However, in applications which employ alternate stopper insertion techniques, chamfering of ends 31 and 32 may not be needed. Further, in order to facilitate the insertion of the closure into the bottle neck, the outer surface can fully or partly be coated with suitable lubricants, for example with silicones. Coating with a lubricant can be carried out by a variety of techniques known in the art, including tumbling and/or extrusion coating. For closures for champagne or sparkling wine, if a silicone lubricant is used a crosslinkable silicone is preferred since silicone can act as an antifoaming agent.

[0402] In order to produce the attributes suitable for use in the wine industry, core member 22 is formed from foam plastic material as described herein using a continuous extrusion process or a moulding process. Extrusion processes are preferred.

[0403] In FIG. 3, the exemplary construction of a closure 20 is depicted comprising a generally cylindrical shape formed by core member 22. In the exemplary aspect, core member 22 comprises a substantially cylindrically shaped surface 26, terminating with substantially flat end surfaces 27 and 28. In FIG. 3, closure 20 is shown without a peripheral layer. While closure 20 is depicted in FIG. 3 with a chamfered end, closure 20 can also be formed without chamfering.

[0404] While the Figures show cylindrical closures, closures for sparkling wine bottles are also encompassed by the invention.

[0405] Any embodiment or aspect described or defined herein, whether defining a closure, a composition, or a method, may be combined with any other aspect or embodiment, or any features thereof, whether defining a closure, a composition, or a method, even when such a combination is not explicitly stated. All combinations of embodiments, aspects and features are within the scope of the present invention. In particular, any aspect of any claim may be combined with any aspect of any one of more claims. Where numerical ranges are defined, any numerical limit of any range may be combined with any other numerical limit of the same range. For example, an upper limit of a range may be combined with an upper limit of a range, or a lower limit of a range may be combined with a lower limit of a range, or an upper limit of a range may be combined with a lower limit of a range, while remaining within the scope of the present invention.

Test Methods:

[0406] The Mocon test for OTR/oxygen ingress rate was carried out using 100% oxygen according to ASTM F-1307.

Extraction Force:

[0407] The test for extraction force was carried out on a random sample selection according to the methods described in WO 03/018304 A1 (extraction test, p. 48, 1. 13-p. 49, 1. 10), which are herewith incorporated and form part of the present disclosure. Three empty, clean Bordeaux style wine bottles were stoppered using a semi-automatic corking machine (Model 4040 from GAI S.p.A., Italy). The bottles were stored for one hour. The closures were then extracted at ambient temperature using a Dillon AFG-1000N force gauge (from Dillon/Quality Plus, Inc., USA) to measure the force required for extraction.

Surface Hardness:

[0408] The surface hardness is tested at room temperature (25? C.) using a Shore 902 automatic operating stand from Instron according to ASTM D2240-10.

Coefficient of Friction:

[0409] The dynamic coefficient of friction was measured according to ASTM D1894-14 at room temperature (25? C.) using an Instron Model 2810 Coefficient of Friction Testing Fixture. For the measurement of the dynamic coefficient of friction, a closure was split in half along its long axis and mounted to a steel plate with the flat side of the interior of the closure. This specimen was then loaded with 200 gram weight and pulled across a stainless steel surface at 15.2 cm/min.

Releasable Haloanisole

[0410] The amount of haloanisole released from a cork into wine can be measured as so-called releasable haloanisole by soaking a cork or a sample of corks in a wine for 24 hours for an untreated cork or 48 hours for a treated cork, and measuring the amount of each haloanisole compound in the wine by means of gas chromatography. An acceptable level is generally considered to be one which results in an amount of the respective chloroanisole or chloroanisoles in the wine which is below the average sensory threshold of about 6 ng/L for TCA or TBA, preferably less than about 2 ng/L.

Surface Roughness:

[0411] The surface roughness R.sub.a was determined using a contact profilometer (Manufacturer: Time Group Inc., Model: TR100 Surface Roughness Tester).

Cork Humidity

[0412] The amount of moisture in the cork particles was measured as the weight loss after 10 minutes heating at 110? C. Method according to ISO 9727-3 and ISO15512:2016.

EXAMPLES

Example 1

Preparation of Coated Cork Particles

[0413] Preparation of 1 kg of material:

[0414] 540 g of cork particles A and 130 g of cork particles B, where cork particle A size>cork particle B size, are poured into a high speed mixer. The cork particles are mixed until the high speed mixer reaches a temperature of 65? C. (due to the friction+a heating jacket). Then 290 g of EVA powder and 40 g of a synthetic wax are poured on the cork particles while mixing. The blend is poured into a cold mixer and mixed while cooling.

Example 2

Formation of a Closure by Moulding Using the Coated Cork Particles

[0415] 9 g of the coated particles obtained in Example 1 are poured into a cylindrical mold (diameter 26 mm approximately), the mold is closed with a press until the cylinder reaches approximately 45 mm length. The mold is placed in an oven at 120? C. for 25 minutes. After cooling until room temperature, the mold is opened. The cylinder obtained (closure precursor) is rectified to obtain a closure with the desired dimensions.

Example 2

Formation of a Closure by Extrusion Using a Mixture of Coated and Uncoated Cork Particles

[0416] The blend composition of the following table was poured into an extruder.

TABLE-US-00001 Cork particles A coated with EVA (70:30) 25% Cork particles B 35% Plastic material 29% Lubricant (d) 6% Blowing agent masterbatch (65 wt. %) 3.8% Color masterbatch (2 wt. %) 1.2%

[0417] Cork particles A were coated as in Example 1. As lubricant (d) a wax suitable for food applications was used. A pigment-plastic material masterbatch comprising 2 wt. % of a food-suitable pigment was used as pigment (e).

[0418] The extruder is equipped with a vacuum system and multiple temperature zones. The temperatures zones are set between 155? C. and 220? C. The extruded rod is cooled down, cut and rectified to obtain a closure with the desired dimensions. The closure obtained has an OTR measured according to the test method disclosed herein within the range disclosed herein.